Myopia: Anatomic Changes and Consequences for Its Etiology

Foveal neural adaptation to optically induced contrast reduction

Contrast processing is suggested to interact with eye growth and myopia development. A novel contrast-reducing myopia control lens design decreases image contrast and was shown to slow myopia progression. Limited insights exist regarding neural visual processing following adaptation to image contrast reduction. This study investigated foveal neural contrast sensitivity in 29 young adults following a 30-minute adaptation to scattering using a Bangerter occlusion foil 0.8, +0.5-diopter defocus, and a clear lens control condition. Neural contrast sensitivity at its peak sensitivity of 6 cycles per degree was assessed before and after adaptation to the lens conditions, employing a unique interferometric system. Pre-adaptation measurements were averaged from six replicates and post-adaptation measurements by the first and last three of six replicates. The change in neural contrast sensitivity was largest for scattering across the first and last three post-adaptation measurements (+0.05 ± 0.01 logCS and +0.04 ± 0.01 logCS, respectively) compared with control and defocus (all +0.03 ± 0.01 logCS). For scattering, the observed increase of neural contrast sensitivity within the first three measurements differed significantly from the pre-adaptation baseline (p = 0.04) and was significantly higher compared with the control condition (p = 0.04). The sensitivity increases in the control and defocus conditions were not significant (all p > 0.05). As the adaptation effect diminished, no significant differences were found from baseline or between the conditions in the last three measurements (all p > 0.05). When post-adaptation neural contrast sensitivities were clustered into 25-second sequences, a significant effect was observed between the conditions, with only a significant relevant effect between control and scattering at 25 seconds (p = 0.04) and no further significant effects (all p > 0.05). The alteration in neural contrast sensitivity at peak sensitivity was most pronounced following adaptation to the scattering condition compared with defocus and control, suggesting that induced scattering might be considered for myopia control.

Relationship between the length of macular Bruch's membrane on fundus photograph and myopia occurrence in pre-myopia children aged 3-6 years: A 3-year longitudinal study

PURPOSE

To evaluate the occurrence and influencing factors of myopia occurrence in pre-myopia children aged 3-6 years.

METHODS

This study included 204 pre-myopia (-0.50D

RESULTS

Mean age at initial visit was 4.28 ± 0.98 years and mean SE was 0.45 ± 0.29D. Both at baseline and after 3 years of follow-up, axial length was longer in boys than that in girls. (all P < 0.001) Children were divided into two groups according to the refractive status of children at the final follow-up: Myopia group (SE≤-0.50D) and Non-myopia group (SE>-0.50D). The length of macular BM was shorter in Myopia group than that in Non-myopia group (P < 0.001). Baseline SE and the length of macular BM were independent influencing factors which associated with myopia occurrence (OR, 0.031; 95 % CI, 0.008-0.117, P < 0.001 and OR, 0.204; 95 % CI, 0.055-0.763, P = 0.018, respectively) by multivariate binary logistic regression analysis. SE changing process represented the changes of SE, Myopia group had bigger SE changes (P < 0.001). And in the multivariate liner regression analysis, age was the common influencing factor of SE changing process in total participants, Non-myopia group and Myopia group (B = 0.234, P < 0.001; B = 0.078, P = 0.010; B = 0.161, P = 0.046, respectively) CONCLUSIONS: Initial SE and the length of macular BM in pre-myopia children aged 3-6 years were the independent factors of the occurrence of myopia. And initial age was the common factor that associated with SE changing process.

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Key Words

• Pre-myopia
• The length of macular Bruch's membrane

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Affiliation(s)

Xuejing Mi Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University, Beijing Ophthalmology & Visual Sciences Key Lab, Beijing, 100730, China
Yuxin Fang Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University, Beijing Ophthalmology & Visual Sciences Key Lab, Beijing, 100730, China
Jianing Pu Maternal and Child Health Hospital of Haidian District, Beijing, China
Wei Chen Maternal and Child Health Hospital of Haidian District, Beijing, China
Zhen Zhou School of Biomedical Engineering, Capital Medical University, Beijing, China
Mengmeng Qin School of Geosciences and Surveying Engineering, China University of Mining and Technology-Beijing, Beijing, 100083, China
Ranran Zhang Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University, Beijing Ophthalmology & Visual Sciences Key Lab, Beijing, 100730, China
Dan Wang Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University, Beijing Ophthalmology & Visual Sciences Key Lab, Beijing, 100730, China
Yanyan Yang Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University, Beijing Ophthalmology & Visual Sciences Key Lab, Beijing, 100730, China
Chuzhi Peng Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University, Beijing Ophthalmology & Visual Sciences Key Lab, Beijing, 100730, China
Shimeng Bian Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University, Beijing Ophthalmology & Visual Sciences Key Lab, Beijing, 100730, China
Mingrui Jin Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University, Beijing Ophthalmology & Visual Sciences Key Lab, Beijing, 100730, China
Huaying Xu Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University, Beijing Ophthalmology & Visual Sciences Key Lab, Beijing, 100730, China
Yonghong Jiao Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University, Beijing Ophthalmology & Visual Sciences Key Lab, Beijing, 100730, China.

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Temporal vascular arcade angle in fundus image was associated with the rate of spherical equivalent refractive error and axial length changes in myopia children with young school age

PURPOSE

To evaluate temporal vascular arcade angle and its influencing factors in myopic children.

METHODS

It was a retrospective study, we reviewed the records of 119 patients aged 6-10 years with myopia (spherical equivalent refractive error (SER) ≤ -0.05D) in the third year of follow-up in Beijing Hyperopia Reserve Research. We measured temporal vascular arcade angles on the fundus photographs and measured 3-year rate of spherical equivalent(D/year) and axial length (AXL) changes(mm/year).

RESULTS

Mean age at initial visit was 7.71±1.20 years and mean SER was -1.32±1.09D. Children were divided into two groups according to the refractive status of children at baseline: Myopia onset group (SER>-0.50D at baseline) (n = 107) and Myopia progression group (SER≤-0.50D at baseline) (n = 12). The mean SER in Myopia progression group was much smaller than Myopia onset group (P < 0.001) and mean AXL in Myopia progression group was much longer than Myopia onset group (P = 0.042). AXL (r=-0.320, P < 0.001), SER change rate (r=-0.209, P = 0.022) and AXL change rate (r=-0.232, P = 0.011) were associated with temporal vascular arcade angle in all participants. In Myopia onset group, AXL (r=-0.317, P < 0.001) and AXL change rate (r=-0.190, P = 0.05) were associated with temporal vascular arcade angle. There were no parameters were associated with temporal vascular arcade angle (all P > 0.05) in Myopia progression group. Only AXL (r=-0.306, P = 0.018) was associated with temporal vascular arcade angle in girls while AXL (r=-0.370, P = 0.004), SER change rate (r=-0.317, P = 0.013) and AXL change rate (r=-0.365, P = 0.004) were all associated with the Angle in boys.

CONCLUSION

Temporal vascular arcade angle was associated with the rate of SER and AXL changes in myopia onset children, and showed gender differences. These may suggest that lamina cribrosa location has different influencing factors in different genders and different stages of myopia development. Due to the small number of people in Myopia progression group, large sample size studies are still needed in the future.

Adaptive Changes in Neurovascular Properties With Binocular Accommodation Functions in Myopic Participants by 3D Visual Training: An EEG and fNIRS Study

Although three-dimensional visual training (3DVT) has been used for myopia intervention, its neural mechanisms remain largely unknown. In this study, visual function was examined before and after 3DVT, while resting-state EEG-fNIRS signals were recorded from 38 myopic participants. A graph theoretical analysis was applied to compute the neurovascular properties, including static brain networks (SBNs), dynamic brain networks (DBNs), and dynamic neurovascular coupling (DNC). Correlations between the changes in neurovascular properties and the changes in visual functions were calculated. After 3DVT, the local efficiency and node efficiency in the frontal lobes increased in the SBNs constructed from EEG δ -band; the global efficiency and node efficiency in the frontal-parietal lobes decreased in the DBNs variability constructed from EEG δ -band. For the DNC constructed with EEG α -band and oxyhemoglobin (HbO), the local efficiency decreased, for EEG α -band and deoxyhemoglobin (HbR), the node efficiency in the frontal-occipital lobes decreased. For the SBNs constructed from HbO, the functional connectivity (FC) between the frontal-occipital lobes increased. The DNC constructed between the FC of the frontal-parietal lobes from EEG β -band and the FC of the frontal-occipital lobes from HbO increased, and between the FC of the frontal-occipital lobes from EEG β -band and the FC of the inter-frontal lobes from HbR increased. The neurovascular properties were significantly correlated with the amplitude of accommodation and accommodative facility. The result indicated the positive effects of 3DVT on myopic participants, including improved efficiency of brain networks, increased FC of SBNs and DNC, and enhanced binocular accommodation functions.

Suitability of multifunction devices Myah and Myopia Master for monitoring myopia progression in children and adults

PURPOSE

To assess the feasibility of using multifunction instruments to measure axial length for monitoring myopia progression in children and adults.

METHODS

Axial length was measured in 60 children (aged 6-18 years) and 60 adults (aged 19-50 years) with multifunction instruments (Myah and Myopia Master) and stand-alone biometers (Lenstar LS900 and IOLMaster 700). Repeatability (measurements by the same examiner) and reproducibility (measurements by different examiners) were computed as the within-subject standard deviation (Sw) and 95% limits of agreement (LoA). Inter-instrument agreement was computed as intraclass correlation coefficients. The threshold for detecting myopic progression was taken as 0.1 mm. Measures were repeated only in children following the administration of 1% tropicamide to determine the impact of cycloplegia on axial length.

RESULTS

Overall, the IOLMaster 700 had the best repeatability in children (0.014 mm) and adults (0.009 mm). Repeatability Sw values for all devices ranged from 0.005 to 0.021 mm (children) and 0.003 to 0.016 mm (adults). In children, reproducibility fell within 0.1 mm 95% of the time for the Myah, Myopia Master and IOLMaster 700. Agreement among all devices was classified as excellent (ICC 0.999; 95% CI 0.998-0.999), but the 95% LoA among the Myah, Myopia Master and Lenstar LS900 was ≥0.1 mm. Cycloplegia had no statistically significant effect on axial length (all p > 0.13).

CONCLUSIONS

The Myah and Myopia Master multifunction instruments demonstrated good repeatability and reproducibility, and their accuracy was comparable to stand-alone biometers. Axial length measurements using different instruments can be considered interchangeable but should be compared with some caution. Accurate axial length measurements can be obtained without cycloplegia. The multifunction instruments Myah and Myopia Master are as well suited for monitoring myopia progression in children as the stand-alone biometers IOLMaster 700 and Lenstar LS900.

Corneal stress‒strain index in relation to retinal nerve fibre layer thickness among healthy young adults

BACKGROUND/OBJECTIVES

To determine the relationship between corneal stress-strain index (SSI) and retinal nerve fibre layer (RNFL) thickness.

SUBJECTS/METHODS

1645 healthy university students from a university-based study contributed to the analysis. The RNFL thickness was measured by high-definition optical coherence tomography (HD-OCT), axial length (AL) was measured by IOL Master, and corneal biomechanics including SSI, biomechanical corrected intraocular pressure (bIOP), and central corneal thickness (CCT) were measured by Corvis ST. Multivariate linear regression was performed to evaluate the relationship between the SSI and RNFL thickness after adjusting for potential covariates.

RESULTS

The mean age of the participants was 19.0 ± 0.9 years, and 1132 (68.8%) were women. Lower SSI was significantly associated with thinner RNFL thickness ( β =8.601, 95% confidence interval [CI] 2.999-14.203, P  = 0.003) after adjusting for age, CCT, bIOP, and AL. No significant association between SSI and RNFL was found in men, while the association was significant in women in the fully adjusted model. The association was significant in the nonhigh myopic group ( P for trend = 0.021) but not in the highly myopic group. Eyes with greater bIOP and lower SSI had significantly thinner RNFL thickness.

CONCLUSIONS

Eyes with lower SSI had thinner RNFL thickness after adjusting for potential covariates, especially those with higher bIOP. Our findings add novel evidence of the relationship between corneal biomechanics and retinal ganglion cell damage.

Intravitreal panitumumab and myopic macular degeneration

BACKGROUND

In experimental studies, intravitreally applied antibodies against epidermal growth factor (EGF), EGF family members (amphiregulin, neuregulin-1, betacellulin, epigen, epiregulin) and against the EGF receptor (EGFR) were associated with a reduction in lens-induced axial elongation and decrease in physiological eye elongation in guinea pigs and in non-human primates. Here, we investigated the intraocular tolerability and safety of a fully human monoclonal IgG2-antibody against EGFR, already in clinical use in oncology, as a potential future therapeutic approach for axial elongation in adult eyes with pathological myopia.

METHODS

The clinical, monocentre, open-label, multiple-dose, phase-1 study included patients with myopic macular degeneration of stage 4, who received intravitreal injections of panitumumab in various doses and in intervals ranging between 2.1 months and 6.3 months.

RESULTS

The study included 11 patients (age:66.8±6.3 years), receiving panitumumab injections in doses of 0.6 mg (4 eyes; 1×1 injection, 3×2 injections), 1.2 mg (4 eyes; 1×1 injection, 2×2 injections, 1×3 injections) and 1.8 mg (3 eyes; 1×1 injection, 2×2 injections), respectively. None of the participants showed treatment-emergent systemic adverse events or intraocular inflammatory reactions. Best-corrected visual acuity (1.62±0.47 logarithm of the minimal angle of resolution (logMAR) vs 1.28±0.59 logMAR; p=0.08) and intraocular pressure (13.8±2.4 mm Hg vs 14.3±2.6 mm Hg; p=0.20) remained unchanged. In nine patients with a follow-up of >3 months (mean:6.7±2.7 months), axial length did not change significantly (30.73±1.03 mm vs 30.77±1.19 mm; p=0.56).

CONCLUSIONS

In this open-labelled, phase-1 study with a mean follow-up of 6.7 months, panitumumab repeatedly administered intravitreally up to a dose of 1.8 mg was not associated with intraocular or systemic adverse effects. During the study period, axial length remained unchanged.

TRIAL REGISTRATION NUMBER

DRKS00027302.

Sustained Retinal Defocus Increases the Effect of Induced Myopia on the Retinal Astrocyte Template

The aim of this article is to describe sustained myopic eye growth's effect on astrocyte cellular distribution and its association with inner retinal layer thicknesses. Astrocyte density and distribution, retinal nerve fiber layer (RNFL), ganglion cell layer, and inner plexiform layer (IPL) thicknesses were assessed using immunochemistry and spectral-domain optical coherence tomography on seventeen common marmoset retinas (Callithrix jacchus): six induced with myopia from 2 to 6 months of age (6-month-old myopes), three induced with myopia from 2 to 12 months of age (12-month-old myopes), five age-matched 6-month-old controls, and three age-matched 12-month-old controls. Untreated marmoset eyes grew normally, and both RNFL and IPL thicknesses did not change with age, with astrocyte numbers correlating to RNFL and IPL thicknesses in both control age groups. Myopic marmosets did not follow this trend and, instead, exhibited decreased astrocyte density, increased GFAP+ spatial coverage, and thinner RNFL and IPL, all of which worsened over time. Myopic changes in astrocyte density, GFAP+ spatial coverage and inner retinal layer thicknesses suggest astrocyte template reorganization during myopia development and progression which increased over time. Whether or not these changes are constructive or destructive to the retina still remains to be assessed.

High myopia at high altitudes

Background: Optic nerve sheath diameter (ONSD) increases significantly at high altitudes, and is associated with the presence and severity of acute mountain sickness (AMS). Exposure to hypobaria, hypoxia, and coldness when hiking also impacts intraocular pressure (IOP). To date, little is known about ocular physiological responses in trekkers with myopia at high altitudes. This study aimed to determine changes in the ONSD and IOP between participants with and without high myopia (HM) during hiking and to test whether these changes could predict symptoms of AMS. Methods: Nine participants with HM and 18 without HM participated in a 3-day trek of Xue Mountain. The ONSD, IOP, and questionnaires were examined before and during the trek of Xue Mountain. Results: The ONSD values increased significantly in both HM (p = 0.005) and non-HM trekkers (p = 0.018) at an altitude of 1,700 m. In the HM group, IOP levels were greater than those in the non-HM group (p = 0.034) on the first day of trekking (altitude: 3,150 m). No statistically significant difference was observed between the two groups for the values of ONSD. Fractional changes in ONSD at an altitude of 1,700 m were related to the development of AMS (r pb = 0.448, p = 0.019) and the presence of headache symptoms (r pb = 0.542, p = 0.004). The area under the ROC curve for the diagnostic performance of ONSD fractional changes at an altitude of 1,700 m was 0.859 for predicting the development of AMS and 0.803 for predicting the presence of headache symptoms. Conclusion: Analysis of changes in ONSD at moderate altitude could predict AMS symptoms before an ascent to high altitude. Myopia may impact physiological accommodation at high altitudes, and HM trekkers potentially demonstrate suboptimal regulation of aqueous humor in such environments.

Metabolomic profiling of ocular tissues in rabbit myopia: Uncovering differential metabolites and pathways

To investigate the metabolic difference among tissue layers of the rabbits' eye during the development of myopia using metabolomic techniques and explore any metabolic links or cascades within the ocular wall. Ultra Performance Liquid Chromatography - Mass Spectrometry (UPLC-MS) was utilized for untargeted metabolite screening (UMS) to identify the significant differential metabolites produced between myopia (MY) and control (CT) (horizontal). Subsequently, we compared those key metabolites among tissues (Sclera, Choroid, Retina) of MY for distribution and variation (longitudinal). A total of 6285 metabolites were detected in the three tissues. The differential metabolites were screened and the metabolic pathways of these metabolites in each myopic tissue were labeled, including tryptophan and its metabolites, pyruvate, taurine, caffeine metabolites, as well as neurotransmitters like glutamate and dopamine. Our study suggests that multiple metabolic pathways or different metabolites under the same pathway, might act on different parts of the eyeball and contribute to the occurrence and development of myopia by affecting the energy supply to the ocular tissues, preventing antioxidant stress, affecting scleral collagen synthesis, and regulating various neurotransmitters mutually.

Bruch's membrane and Brücke's muscle in the pars plana region

PURPOSE

To examine Bruch's membrane (BM) in association with the longitudinal part of the ciliary muscle (LPCM) in the pars plana region.

METHODS

Using light microscopy, we histomorphometrically assessed BM and the LPCM in the pars plana region.

RESULTS

The histomorphometric study included 51 eyes (51 patients; mean age: 60.8 ± 15.0 years; axial length: 26.0 ± 3.3 mm; range: 21.0-36.0 mm). The LPCM (total length: 4.60 ± 1.10 mm) ended 1.15 ± 0.56 mm anterior to the ora serrata. Within the pars plana region, the LPCM (length: 2.58 ± 0.98 mm) had direct contact with BM for 1.95 ± 0.99 mm (71.1 ± 18.4% of the BM undersurface), while a capillary layer was interposed between the BM and the LPCM for 0.70 ± 0.40 mm (29.0 ± 18.4%). In the pars plana region free of LPCM close to the ora serrata, the percentage of BM covered by the capillary layer was higher than in the pars plana region containing the LPCM (63.0 ± 42.1% vs. 29.0 ± 18.4%; p < 0.001). At the LPCM end, BM was in direct contact with a collagenous tissue from the LPCM and was focally thickened as compared to BM with an underlying capillary layer (9.5 ± 5.3 μm vs. 4.3 ± 1.2 μm; p < 0.001).

CONCLUSIONS

The direct contact of BM with the LPCM in the pars plana in association with focal BM thickening at the LPCM end suggests an insertion of LPCM on the BM. Taking into account the biomechanical strength of BM, it may imply a functional unit of the LPCM with BM in the process of accommodation with a secondary movement of the posterior BM and tertiary thickening of the subfoveal choroidal space.

Optic Nerve Head Curvature Flattening Is Associated with Central Visual Field Scotoma

This study aimed to develop a new index, the average curvature ratio (ACR), to represent the optic nerve head (ONH) tilting and investigate its clinical relevance. Myopic eyes were included and divided into two subgroups: flat ONH (ACR < 1.0) and convex ONH (ACR ≥ 1.0). The occurrences of central and peripheral visual field (VF) defects were compared between the two groups. A total of 375 myopic eyes were recruited, and 231 and 144 eyes were included in the flat and convex ONH groups, respectively. Central scotoma occurred more frequently in the flat ONH group. According to the Patella-Anderson criteria, the number of eyes with central scotoma was 103 (44.6%) in the flat and 44 (30.6%) in the convex ONH groups (p = 0.009). According to Kook's criteria, the number of eyes with central scotoma was 122 (52.8%) in the flat and 50 (34.7%) in the convex ONH groups (p < 0.001). Peripheral scotoma was not significantly different between the groups. In the correlation analysis, the ACR was positively correlated with spherical equivalence, but not with axial length or central corneal thickness. The ACR reflects the degree of the ONH tilt and is a good index for estimating central VF damage in myopic eyes.

[The association between myopia and glaucoma]

Myopia and glaucoma are the leading causes of irreversible blindness in the world, and as the number of nearsighted people is predicted to increase sharply in the upcoming decades, an increase in combined pathology is expected. This article analyzes literature sources to assess the epidemiology of glaucoma and myopia both worldwide and in the Russian Federation, examine the anatomical changes of the eyeball associated with these diseases, and identify the diagnostic criteria that facilitate the verification of glaucoma when combined with myopia.

Scleral remodeling in early adulthood: the role of FGF-2

Emmetropization, a natural process of ocular elongation, is closely associated with scleral remodeling. The Fibroblast growth factor-2 (FGF-2) was reported involved in scleral remodeling in myopia models. Herein, we aimed to investigate the role of scleral fibroblast-to-myofibroblast differentiation and FGF-2 in scleral remodeling during maturation. Our findings revealed that the posterior scleral fibroblasts (SFs) from mature guinea pigs exhibit increased stiffness compared to those from young guinea pigs. Moreover, mature SFs displayed decreased cell proliferation but increased levels of α-SMA, matrix metalloproteinase 2 (MMP2), and collagen 1, when compared to young SFs. Additionally, the mRNA expression of scleral Fgf-2, Fgf receptor 1 (Fgfr1), Fgfr2, Fgfr3, and Fgfr4 was increased in mature SFs. Notably, exogenous FGF-2 showed increased cell proliferation and led to decreased expression of α-SMA, MMP2, and collagen 1 in mature SFs. Overall, our findings highlight the influence of maturation on SFs from posterior scleral shells, resulting in increased stiffness and the manifestation of fibroblast-to-myofibroblast differentiation during development. Exogenous FGF-2 increased cell proliferation and reversed the age-related fibroblast-to-myofibroblast differentiation, suggesting a potential role of FGF-2 in regulating scleral remodeling.

Correlation between refractive errors and ocular biometric parameters in children and adolescents: a systematic review and meta-analysis

BACKGROUND

Refractive errors are one of the most common ocular conditions among children and adolescents, with myopia showing an increasing prevalence and early onset in this population. Recent studies have identified a correlation between refractive errors and ocular biometric parameters.

METHODS

A systematic search was conducted in electronic databases including PubMed, EMBASE, Cochrane Library, Web of Science, and Medline from January 1, 2012, to May 1, 2023. Various ocular biometric parameters were summarized under different refractive states, including axial length (AL), central corneal thickness (CCT), anterior chamber depth (ACD), lens thickness (LT), corneal curvature (CC), Corneal curvature radius (CR),axial length-to-corneal radius ratio (AL/CR ratio), choroidal thickness (ChT), retinal thickness (RT), retinal nerve fiber layer thickness (RNFL), and retinal blood density (VD). The differences in these parameters among different refractive states were analyzed using Stata software with fixed or random-effects models, taking into account the assessed heterogeneity level.

RESULTS

This meta-analysis included a total of 69 studies involving 128,178 eyes, including 48,795 emmetropic eyes, 60,691 myopic eyes, 13,983 hyperopic eyes, 2,040 low myopic eyes, 1,201 moderate myopic eyes, and 1,468 high myopic eyes. The results of our study demonstrated that, compared to the control group (emmetropic group), the myopic group and low, moderate, and high myopic groups showed significant increases in AL, AL/CR ratio, and ACD, while the hyperopic group exhibited significant decreases. Compared to the control group, the myopic group had a significantly increase for CC, while CR, CCT, perifoveal RT, subfoveal ChT, foveal ChT, parafoveal ChT, perifoveal (except nasal) ChT, and pRNFL (except temporal) significantly decreased. Compared to the control group, the hyperopic group had a significantly increase for subfoveal ChT, foveal ChT, parafoveal ChT, perifoveal ChT, and nasal pRNFL. Compared to the control group, the low and moderate myopic groups had a significantly decreases for the CCT, parafoveal RT (except nasal), perifoveal RT (except nasal), and pRNFL (except superior and temporal). Compared to the control group, the high myopic group had a significantly increase for CR, while LT, perifoveal ChT (except nasal), parafoveal RT, perifoveal RT, and pRNFL (except temporal) had significant decreased.

CONCLUSION

The changes of ocular biometric parameters in children and adolescents are closely related to refractive errors. Ocular biometric parameters devices, as effective non-invasive techniques, provide objective biological markers for monitoring refractive errors such as myopia.

Parapapillary gamma zone associated with increased peripapillary scleral bowing: the Beijing Eye Study 2011

AIMS

To investigate the association between the backward configuration of the peripapillary sclera (PPS), measured as PPS angle (PPSA), and presence and extent of parapapillary gamma zone.

METHODS

Out of the population-based Beijing Eye Study 2011, we randomly selected individuals free of optic nerve and retinal diseases. With Spectralis optical coherence tomography, we measured gamma zone (zone free of Bruch's membrane (BM)) and determined the PPSA, defined as the angle between the anterior scleral surface lines from both sides of the optic nerve head (ONH).

RESULTS

The study included 678 individuals with age of 59.5±7.6 years (range: 50-90) and axial length of 23.5±1.3 mm (20.9-29.2). Gamma zone was more prevalent in eyes with larger PPSA (p=0.006) after adjustment for axial length (p<0.001) and BM opening area (p<0.001). Gamma zone width was positively associated with PPSA, axial length and BM opening area (all p<0.001) in multivariable analysis. Circular gamma zone was accompanied with larger PPSA as compared with focal gamma zone (19.9°±7.2° vs 6.3°±5.3°, p<0.001). Focal temporal gamma and focal inferior gamma had similar mean PPSA (p=0.69). However, the horizontal PPSA was significantly larger than the vertical PPSA in inferior gamma (6.9°±6.3° vs 4.7°±6.6°; p=0.005), while they were comparable in temporal gamma (6.1°±5.8° vs 6.3°±6.4°; p=0.073).

CONCLUSIONS

A more backward bowing of the PPS was linearly and spatially associated with the presence, size and extent of gamma zone. It suggested that the BM and the sclera were closely related in participating the biomechanical behaviour of the ONH.

Myopia: Histology, clinical features, and potential implications for the etiology of axial elongation

Myopic axial elongation is associated with various non-pathological changes. These include a decrease in photoreceptor cell and retinal pigment epithelium (RPE) cell density and retinal layer thickness, mainly in the retro-equatorial to equatorial regions; choroidal and scleral thinning pronounced at the posterior pole and least marked at the ora serrata; and a shift in Bruch's membrane opening (BMO) occurring in moderately myopic eyes and typically in the temporal/inferior direction. The BMO shift leads to an overhang of Bruch's membrane (BM) into the nasal intrapapillary compartment and BM absence in the temporal region (i.e., parapapillary gamma zone), optic disc ovalization due to shortening of the ophthalmoscopically visible horizontal disc diameter, fovea-optic disc distance elongation, reduction in angle kappa, and straightening/stretching of the papillomacular retinal blood vessels and retinal nerve fibers. Highly myopic eyes additionally show an enlargement of all layers of the optic nerve canal, elongation and thinning of the lamina cribrosa, peripapillary scleral flange (i.e., parapapillary delta zone) and peripapillary choroidal border tissue, and development of circular parapapillary beta, gamma, and delta zone. Pathological features of high myopia include development of macular linear RPE defects (lacquer cracks), which widen to round RPE defects (patchy atrophies) with central BM defects, macular neovascularization, myopic macular retinoschisis, and glaucomatous/glaucoma-like and non-glaucomatous optic neuropathy. BM thickness is unrelated to axial length. Including the change in eye shape from a sphere in emmetropia to a prolate (rotational) ellipsoid in myopia, the features may be explained by a primary BM enlargement in the retro-equatorial/equatorial region leading to axial elongation.

Macular outer nuclear layer, ellipsoid zone and outer photoreceptor segment band thickness, axial length and other determinants

The study aims to assess the thickness of the retinal outer nuclear layer (ONL), ellipsoid zone (EZ) and photoreceptor outer segment (POS) band in various macular regions and its associations with axial length and other parameters. Participants of the Beijing Eye Study 2011 underwent a series of examinations including spectral-domain optical coherence tomography of the macula. The current study included 2213 participants without retinal or optic nerve diseases (age: 61.7 ± 8.4 years; range 50-93 years); axial length: 23.15 ± 0.95 mm; range 18.96-29.15 mm). The ONL (fovea: 98.9 ± 8.8 µm), EZ (fovea: 24.1 ± 0.5 µm) and POS band (fovea: 24.3 ± 3.5 µm) were the thickest (P < 0.001) in the fovea (defined as the thinnest central point), followed by the temporal inner, nasal inner, inferior inner, superior inner, inferior outer, temporal outer, nasal outer, and superior outer region. In multivariable analysis, a thicker retinal ONL was associated (correlation coefficient r: 0.40) with shorter axial length (beta: - 0.14; P < 0.001) and shorter disc-fovea distance (beta: - 0.10; P = 0.001), after adjusting for younger age (beta: - 0.26; P < 0.001), male sex (beta: 0.24; P < 0.001), lower serum cholesterol concentration (beta: - 0.05; P = 0.04), and thicker subfoveal choroidal thickness (beta: 0.08; P < 0.001). The POS thickness increased with shorter axial length (beta: - 0.06; P < 0.001) and shorter optic disc-fovea distance (beta: - 0.05; P = 0.03), after adjusting for younger age (beta: - 0.34; P < 0.001), male sex (beta: 0.15; P < 0.001), and thicker subfoveal choroidal thickness (beta: 0.24; P < 0.001). As a conclusion, the photoreceptor ONL, EZ and POS band vary in thickness between different macular regions and differ in their correlations with axial length, disc-fovea distance, age, sex, and subfoveal choroidal thickness. The ONL thickness decrease with longer axial length and longer disc-fovea distance may point to an axial elongation-associated retinal stretching in the macula.

Swept-Source OCT Mid-Peripheral Retinal Irregularity in Retinal Detachment and Posterior Vitreous Detachment Eyes

Irregularities in retinal shape have been shown to correlate with axial length, a major risk factor for retinal detachment. To further investigate this association, a comparison was performed of the swept-source optical coherence tomography (SS OCT) peripheral retinal shape of eyes that had either a posterior vitreous detachment (PVD) or vitrectomy for retinal detachment. The objective was to identify a biomarker that can be tested as a predictor for retinal detachment. Eyes with a PVD (N = 88), treated retinal detachment (N = 67), or retinal tear (N = 53) were recruited between July 2020 and January 2022 from hospital retinal clinics in South Australia. The mid-peripheral retina was imaged in four quadrants with SS OCT. The features explored were patient age, eye axial length, and retinal shape irregularity quantified in the frequency domain. A discriminant analysis classifier to identify retinal detachment eyes was trained with two-thirds and tested with one-third of the sample. Retinal detachment eyes had greater irregularity than PVD eyes. A classifier trained using shape features from the superior and temporal retina had a specificity of 84% and a sensitivity of 48%. Models incorporating axial length were less successful, suggesting peripheral retinal irregularity is a better biomarker for retinal detachment than axial length. Mid-peripheral retinal irregularity can identify eyes that have experienced a retinal detachment.

Effects of exogenous retinoic acid on ocular parameters in Guinea pigs with form deprivation myopia

Aim: Myopia is a common chronic eye disease, this study is to investigate the effects of exogenous retinoic acid (RA) on intraocular parameters, especially choroidal thickness (CT) and retinal thickness (RT), in guinea pigs with form deprivation myopia (FDM).

Methods: A total of 80 male guinea pigs were divided randomly into 4 groups: Control, FDM, FDM + RA, and FDM + Citral groups. The FDM + RA group was given 24 mg/kg RA dissolved in 0.4 mL peanut oil; the FDM + Citral group was given citral 445 mg/kg dissolved in 0.4 mL peanut oil; The other two groups were given 0.4 mL peanut oil. After 4 weeks, the refractive error (RE), axial length (AL), and intraocular pressure (IOP) of all guinea pigs were measured, and the parameters of RT and CT were obtained using enhanced depth imaging optical coherence tomography (EDI-OCT).

Results: After 4 weeks, both the RE and AL in the FDM and FDM + RA groups were increased, and the RT and CT in both groups were smaller than those in the Control group (p &lt; 0.05). Only the IOP of the right eye in the FDM + RA group increased significantly (p &lt; 0.05). The RT of the right eye of the 4 groups was compared: Control group &gt; FDM + Citral group &gt; FDM group &gt; FDM + RA group. Compared with the RT of the left eye and the right eye among the 4 groups, the RT of the right eye in the FDM and FDM + RA groups was significantly less than that in the left eye (p &lt; 0.05). Moreover, the CT of the right eye in the Control group was greater than that in the other three groups (p &lt; 0.0001). There was no significant difference in the CT among the FDM, FDM + RA, and FDM + Citral groups (p &gt; 0.05). In contrast to the RT results, the CT results of the left and right eyes in the FDM + Citral group showed statistically significant differences (p &lt; 0.05).

Conclusion: RA participates in the progression of FDM as a regulatory factor. Exogenous RA can increase the RE, AL, and IOP of FDM guinea pigs, and might aggravate the retinal thinning of FDM guinea pigs. Citral can inhibit these changes, but RA might not affect the thickness of the choroid.

Myopic tilted disc: Mechanism, clinical significance, and public health implication

Myopic tilted disc is a common structural change of myopic eyes. With advancing ocular imaging technology, the associated structural changes of the eye, particularly the optic nerve head, have been extensively studied. These structural changes may increase patients' susceptibility to axonal damage and the risk of developing serious optic neuropathies including glaucoma. They also lead to diagnostic difficulties of disease suspects and treatment dilemmas of patients, which implicate clinical practice and subsequently the health care system. In the context of the mounting prevalence of myopia worldwide and its implications to irreversible visual impairment and blindness, it is essential to gain a thorough understanding of the structural changes of myopia. Myopic tilted disc has been extensively investigated by different study groups. However, generalizing the knowledge could be difficult because of the variable definitions of myopic tilted disc utilized in these studies and the complexities of the changes. The current review aimed to clarify the concepts and discuss various aspects of myopic tilted disc, including the definitions, association with other myopia-related changes, mechanism of tilted disc development, structural and functional changes, and clinical implications.

Anatomic Peculiarities Associated with Axial Elongation of the Myopic Eye

PURPOSE

To describe anatomical peculiarities associated with axial elongation in the human myopic eye.

METHODS

Reviewing the results of previous histomorphometrical investigations of enucleated human globes, as well as reviewing findings obtained in population-based studies and hospital-based clinical investigations of myopic patients and non-myopic individuals.

RESULTS

Myopic axial elongation is associated with a change from a mostly spherical eye shape to a prolate ellipsoid form. It is combined with choroidal and scleral thinning, most pronounced at the posterior pole and less pronounced in the fundus midperiphery. In the fundus midperiphery, the retina and density of the retinal pigment epithelium (RPE) and photoreceptors decrease with a longer axial length, while in the macular region, retinal thickness, RPE cell density, and choriocapillaris thickness are not related to axial length. With axial elongation, a parapapillary gamma zone develops, leading to an enlargement of the optic disc-fovea distance and a decrease in angle kappa. Axial elongation is also correlated with an increase in the surface and volume of Bruch's membrane (BM), while BM thickness remains unchanged. Axial elongation causes moderately myopic eyes to show a shift of BM opening to the foveal direction so that the horizontal disc diameter becomes shorter (with a consequent vertical ovalization of the optic disc shape), a temporal gamma zone develops, and the optic nerve exit takes an oblique course. Features of high myopia are an enlargement of the RPE opening (myopic parapapillary beta zone) and BM opening (secondary macrodisc), elongation and thinning of the lamina cribrosa, peripapillary scleral flange (parapapillary delta zone) and peripapillary choroidal border tissue, secondary BM defects in the macular region, myopic maculoschisis, macular neovascularization, and cobblestones in the fundus periphery.

CONCLUSIONS

These features combined may be explained by a growth in BM in the fundus midperiphery leading to axial elongation.

Myopic macular Bruch's membrane defects

Purpose

To examine histologic characteristics of macular Bruchś membrane defects (BMD) in axially elongated eyes.

Design

Histomorphometric study.

Methods

Using light microscopy, we examined enucleated human globes for BMDs.

Results

In 247 eyes, BMDs were detected in 15 (6.1%) eyes (axial length:27.0-36.0 mm), in 10 of them in the macular region. Prevalence and size of BMDs (mean:1.93 ± 1.62 mm; range:0.22mm-6.24 mm) correlated with longer axial length (OR:1.52; 95%CI:1.19,1.94; P = 0.001) and higher prevalence of scleral staphylomas (OR:16.3; 95%CI:2.67,99.3; P < 0.001). The BMDs were smaller than corresponding gaps in the retinal pigment epithelium (RPE) (1.93 ± 1.62 mm versus 2.61 mm ± 1.73 mm; P = 0.003), and larger than corresponding gaps in the inner nuclear layer (0.43 ± 0.76 mm; P = 0.008) and inner limiting membrane bridges (0.13 ± 0.33 mm; P = 0.001). Choriocapillaris thickness, BM thickness and RPE cell density did not vary (all P > 0.05) between the BDM border and adjacent areas. In the BMD, choriocapillaris and RPE were absent. The sclera was thinner in the BDM area than in adjacent areas (0.28 ± 0.19 mm versus 0.36 ± 0.13 mm; P = 0.006).

Conclusions

BMDs as hallmarks of myopic macular degeneration are characterized by longer gaps in the RPE and smaller gaps in the outer nuclear layer and inner nuclear layer, by localized scleral thinning, and by a spatial association with scleral staphylomas. Thickness of the choriocapillaris and density of the RPE cell layer, both absent within the BDMs, do not vary between the BMD border and adjacent regions. The results suggest an association between BDMs and absolute scotomas, stretching of the adjacent retinal nerve fiver layer, and an axial elongation-associated stretching effect on BM as etiology of the BDMs.

Retinal Proteome Analysis Reveals a Region-Specific Change in the Rabbit Myopia Model

Uncovering region-specific changes in the myopic retina can provide clues to the pathogenesis of myopia progression. After imposing form deprivation myopia in the right eye of 6-week-old rabbits, we investigated the proteome profile of each retinal region (central, mid-periphery, and far-periphery retina), using accurate high-resolution mass spectrometry. Protein expression was analyzed using gene ontology and network analysis compared with that of the control, the left eyes. Among 2065 proteins detected from whole retinal samples, 249 differentially expressed proteins (DEPs) were identified: 164 DEPs in the far-periphery, 39 in the mid-periphery, and 83 in the central retina. In network analysis, the far-periphery retina showed the most significant connectivity between DEPs. The regulation of coagulation was the most significant biological process in upregulated DEPs in the far-periphery retina. Proteasome was the most significant Kyoto Encyclopedia of Genes and Genomes pathway in downregulated DEPs in the central retina. Antithrombin-III, fibrinogen gamma chain, and fibrinogen beta chain were identified as hub proteins for myopia progression, which were upregulated in the far-periphery retina. Proteomic analysis in this study suggested that oxidative stress can be the primary pathogenesis of myopia progression and that the far-periphery retina plays a role as the key responder.

Inner limiting membrane bridges within Bruch's membrane defects in pathological myopia

The purpose of the study was to examine peculiarities of the inner limiting membrane (ILM) in axially elongated eyes. The histomorphometric study included human globes enucleated due to reasons such as painful secondary angle-closure glaucoma or malignant uveal melanomas. Using light microscopy, we searched for regions with ILM-specific features in association with a marked axial elongation. Out of 279 eyes (279 patients) (mean age: 61.8 ± 13.9 years; axial length: 25.5 ± 3.1 mm (range: 20.0-37.0 mm)), two eyes (axial length: 30 mm and 34 mm, respectively) showed one region and two regions, respectively, characterized by ILM presence and absence of all other retinal layers, retinal pigment epithelium, Bruch´s membrane (BM) and choroid. The length of these regions, called ILM-bridges, was 1.06 mm, 0.73 mm, and 0.62 mm, respectively. All ILM-bridges were spatially associated with a larger, underlying BM defect and with localized scleral thinning without a staphylomatous scleral configuration. The distance between the ILM-bridges and the optic disc ranged between 1.92 mm and 4.21 mm. In univariable analysis, ILM-bridge number increased with longer axial length (beta: 0.19; P = 0.002) and higher BM defect prevalence (beta: 0.21; P = 0.001), while in multivariable analysis, the ILM-bridges number remained to be significantly correlated only with a higher prevalence of BM defect (beta: 0.15; P = 0.048). ILM-bridges occur in eyes with pathologic myopia in spatial association with underlying, larger BM defects. They may be due to an axial elongation-associated local stretching and rupture of all other retinal layers, caused by the BM defect-related enlargement of the retinal undersurface. Future studies may explore whether these histologic observations support the notion of the ILM having a relatively high biomechanical strength against myopic stretching-associated forces.

Photoreceptor density in relation to axial length and retinal location in human eyes

The purpose of the study was to examine the density of retinal photoreceptors and retinal pigment epithelium (RPE) cells in relation to myopic axial elongation in human eyes. Using light microscopy, we assessed the density of photoreceptors and RPE cells at the ora serrata, equator, and midperiphery (equator/posterior pole midpoint), and the RPE cell density additionally at the posterior pole, in enucleated human globes. The study included 78 eyes (mean age: 59.2 ± 15.6 years; range: 32-85 years) with a mean axial length of 27.3 ± 3.6 mm (range: 21.5-37.0 mm). Close to the ora serrata, at the equator and midperiphery, photoreceptor and RPE cell density was 246 ± 183, 605 ± 299 and 1089 ± 441 photoreceptors/mm and 56.1 ± 13.7, 45.2 ± 15.1, and 48.8 ± 15.6 RPE cells/mm, respectively. Densities of both cell types in all three regions were positively correlated with each other (all P < 0.001) and decreased with longer axial length (all P < 0.001) and longer distance between the ora serrata and the posterior pole (all P < 0.001), most marked at the midperiphery and least marked close to the ora serrata. The PRE cell density at the posterior pole was not significantly (P = 0.35) related to axial length. The photoreceptor density at the ora serrata (beta:- 0.33) and equator (beta: - 0.27) and RPE cell density at the ora serrata (beta: - 0.27) decreased additionally with the presence of glaucoma. The findings suggest that the axial elongation-related decrease in photoreceptor and RPE cell density is most marked at the midperiphery, followed by the equator and finally the ora serrata region. It suggests that the axial elongation-related enlargement of the eye wall predominantly takes place in the retro-equatorial region, followed by the equatorial region.

Changes in retinal vascular bifurcation in eyes with myopia

Objective

To evaluate the effect of myopia on retinal vascular bifurcation.

Methods

A cross-sectional study that retrospectively analyzed the fundus photographs and clinical data of 493 people who participated in routine physical examinations in Huadong Sanatorium. One eye of each subject was included in the analysis. Retinal vascular bifurcation measurements were extracted by using a validated computer program. One-way ANOVA and analysis of covariance were performed to compare the measurements across high myopia, low to moderate myopia, and non-myopia groups.

Results

The mean age was 41.83 ± 10.43 years and 63.49% were women. The mean spherical equivalent refraction (SER) was − 4.59 ± 3.07 D. Ninety-nine (20.08%) eyes met the definition of high myopia (SER ≤ -6.0 D), along with 234 (47.46%) low to moderate myopia (-6.0 D < SER <-0.5 D), and 160 (32.45%) non-myopia (SER ≥ -0.5 D). The differences in the arteriolar branching angle, venular branching coefficient, venular asymmetry ratio, venular angular asymmetry, and venular junctional exponent among the three groups remained significant (p < 0.05) after multivariate adjustment. Pairwise comparisons showed arteriolar branching angle and venular angular asymmetry in high myopia were significantly lower than low to moderate myopia (p < 0.001, p = 0.014 respectively) and non-myopia (p = 0.007, p = 0.048 respectively). Venular asymmetry ratio and venular branching coefficient in high myopia were significantly higher than low to moderate myopia (p = 0.029, p = 0.001 respectively) and non-myopia (p = 0.041, p = 0.043 respectively). There was a significant difference in venular junctional exponent between high myopia and low to moderate myopia (p = 0.031).

Conclusion

The vascular bifurcation differs in dependence on the myopic refractive error and a significant increase in the difference can be observed in high myopic eyes.

Expression of SCO1 and SCO2 after form-deprivation myopia in Guinea pigs

PURPOSE

The retina is a highly energy-consuming tissue associated with visual development, and the reduced quality of retinal imaging can be related to myopia. Synthesis of cytochrome c oxidase 1 (SCO1) and synthesis of cytochrome c oxidase 2 (SCO2) are involved in ATP (adenosine triphosphate) synthesis and energy metabolism. This study aimed to observe the morphologic changes and investigate the expression of SCO1 and SCO2 induced by form-deprivation myopia (FDM) in the retina and sclera of guinea pigs.

METHODS

Thirty-six 3-week-old male guinea pigs were randomly assigned to one of two groups: (1) the model group (n  =  18), in which the right eyes were covered by a thin opaque balloon as FDM group, and the left eyes were uncovered and served as the contralateral control group; (2) the blank control group (n  =  18), in which bilateral eye received no manipulation. Eyeballs were enucleated for histological analysis. The retina and sclera of the guinea pigs were separated to determine the protein and mRNA expression levels of SCO1 and SCO2, respectively.

RESULTS

After four weeks of form deprivation (FD), the refractive degree and axial length increased significantly (P < 0.001). The retinal and scleral tissues were moderately thinner, and the ganglion cells and the cells of inner and outer nuclear layers in the retina became fewer. Compared with the contralateral control group (P < 0.001) and the blank control group (P < 0.001), the collagen content of the sclera became less in the FDM group. The protein and mRNA expression levels of SCO1 and SCO2 in the FDM group were significantly lower than those in the contralateral control group and the blank control group (P < 0.05).

CONCLUSIONS

The morphologies of the retina and sclera were changed, and the expression of SCO1 and SCO2 at the protein and transcription levels was significantly reduced in the FDM group. Given these changes, SCO1 and SCO2 genes may be involved in myopic progression.

A Review of Intraocular Pressure (IOP) and Axial Myopia

The pathogenesis of myopia is driven by genetic and environmental risk factors. Accommodation not only alters the curvature and shape of the lens but also involves contraction of the ciliary and extraocular muscles, which influences intraocular pressure (IOP). Scleral matrix remodeling has been shown to contribute to the biomechanical susceptibility of the sclera to accommodation-induced IOP fluctuations, resulting in reduced scleral thickness, axial length (AL) elongation, and axial myopia. The rise in IOP can increase the burden of scleral stretching and cause axial lengthening. Although the accommodation and IOP hypotheses were proposed long ago, they have not been validated. This review provides a brief and updated overview on studies investigating the potential role of accommodation and IOP in myopia progression.

Changes in Refractive Error Under COVID-19: A 3-Year Follow-up Study

INTRODUCTION

To investigate changes in refractive error in schoolchildren before and during the coronavirus disease 2019 (COVID-19) pandemic.

METHODS

This study included 2792 students, who underwent a 3-year follow-up from 2018 to 2020. All participants underwent yearly noncycloplegic refraction and ocular examinations. Time-related changes in sphere, cylinder, and spherical equivalent (SE) measurements in both genders were analyzed.

RESULTS

The myopic sphere (- 0.78 ± 1.83 vs. - 1.03 ± 1.91 D; P = 0.025) and SE (- 1.04 ± 1.90 vs. - 1.32 ± 1.99 D; P = 0.015) progressed significantly from 2018 to 2019. Female participants had a significantly greater change in SE than male participants (P < 0.05), and the low hyperopia, emmetropia, and mild myopia groups significantly deteriorated (P < 0.001) from 2018 to 2019. Significant differences in sphere change (- 0.21 ± 0.97 vs. - 0.36 ± 0.96 D; P < 0.001) and SE change (- 0.23 ± 0.99 vs. - 0.38 ± 0.98 D; P < 0.001) were noted between 2019-2018 and 2020-2019, respectively. The respective changes in cylinder were statistically similar (- 0.03 ± 0.53 vs. - 0.05 ± 0.62 D; P = 0.400).

CONCLUSIONS

The refractive status of schoolchildren showed an increasing myopic shift trend before and during the COVID-19 pandemic. The low hyperopia, emmetropia, and mild myopia groups were more sensitive to environmental changes during COVID-19 than before. The myopic shift was greater in female participants than male participants.

Progression and associated factors of lacquer cracks/patchy atrophies in high myopia: the Beijing Eye Study 2001-2011

PURPOSE

To assess the development and progression of lacquer cracks/patchy atrophies (LCs/PAs) in high myopia.

METHODS

The case control study included highly myopic eyes (refractive error ≤  - 6.0 diopters), examined in the population-based Beijing Eye Study 2001/2011. Using fundus photographs taken in 2001 and 2011 and optical coherence tomographic images obtained in 2011, we assessed the incidence and enlargement of pre-existing LC/PAs.

RESULTS

The study included 89 highly myopic eyes (age: 65.0 ± 9.4 years). Newly developed or enlarged LC/PAs were detected in 17 (19.1%; 95% confidence interval (CI): 11.0, 27.0) eyes, with a new LC development without previous LCs, enlargement of a pre-existing LC, LC enlargement to a PA, development of a new PA without any previous LCs, and enlargement of a pre-existing PA detected in 3, 3, 5, 3, and 3 eyes, respectively. In 14 (82.4%; 95%CI: 62.3, 100) of the 17 eyes with LC/PA development or enlargement, the LC/PAs elongated perpendicularly to, and widened in, the direction of gamma zone enlargement. Higher prevalence of LC/PA enlargement was associated (multivariable analysis) with higher myopic maculopathy stage in 2001 (odds ratio (OR): 7.83; 95%CI: 2.65, 23.2; P < 0.001) and higher frequency of parapapillary delta zone enlargement (OR: 32.0; 95%CI: 3.07, 334; P < 0.001). Prevalence of LC/PA enlargement was lower than the prevalence of changes in other myopic maculopathy features (disc-fovea distance elongation: 71%; choroidal vessel shift: 55%; reduction in ophthalmoscopical disc size: 34%; ophthalmoscopic disc size enlargement: 25%). All eyes with LC/PA enlargement showed a pre-existing and enlarging gamma zone.

CONCLUSIONS

Development and enlargement of LC/PAs were associated with enlargement of parapapillary delta zone and often occurred in association with the direction of gamma zone enlargement.

Subfoveal scleral thickness is associated with peripheral retinal changes in high myopia in children and adolescents

BACKGROUND

This study aims to identify the risk factors in peripheral retinal changes (PRC) associated with high myopes among children and adolescents.

METHODS

This is a cross-sectional study on children and adolescents diagnosed with high myopia. The subjects involved underwent a series of ocular examinations, including the dilated fundus examination for PRC and the swept-source optical coherence tomography for foveal retinal, choroidal and scleral thickness measurement. Then, the variables were compared among the eyes with high risk, low risk, and no PRC. Spearman correlation was applied to evaluate the relationship between the parameters and the extent of PRC. Logistic regression was performed to identify the potential risk factors.

RESULTS

A total of 117 eyes from 117 subjects were recruited. The prevalence of PRC was 57.3% (67 eyes), while that of high-risk PRC was 22.2% (26 eyes). Significant differences were found in the mean subfoveal scleral thickness, spherical equivalent refraction, and axial length among the eyes with high-risk, low-risk, and no PRC (p < 0.01, p < 0.01, p = 0.048, respectively). Compared with spherical equivalent (r = 0.32, p < 0.01) and axial length (r = 0.18, p = 0.05), subfoveal scleral thickness exhibited higher correlation coefficient with PRC (r =  - 0.38, p < 0.01). Subfoveal scleral thickness and spherical equivalent refraction were identified as the independent risk factors for PRC and high-risk PRC.

CONCLUSION

It was demonstrated that there was a correlation between subfoveal scleral thickness and PRC. The eyes with thinner subfoveal scleral thickness carried a higher risk of PRC.

Fluorescent Nanosystems for Drug Tracking and Theranostics: Recent Applications in the Ocular Field

The greatest challenge associated with topical drug delivery for the treatment of diseases affecting the posterior segment of the eye is to overcome the poor bioavailability of the carried molecules. Nanomedicine offers the possibility to overcome obstacles related to physiological mechanisms and ocular barriers by exploiting different ocular routes. Functionalization of nanosystems by fluorescent probes could be a useful strategy to understand the pathway taken by nanocarriers into the ocular globe and to improve the desired targeting accuracy. The application of fluorescence to decorate nanocarrier surfaces or the encapsulation of fluorophore molecules makes the nanosystems a light probe useful in the landscape of diagnostics and theranostics. In this review, a state of the art on ocular routes of administration is reported, with a focus on pathways undertaken after topical application. Numerous studies are reported in the first section, confirming that the use of fluorescent within nanoparticles is already spread for tracking and biodistribution studies. The first section presents fluorescent molecules used for tracking nanosystems’ cellular internalization and permeation of ocular tissues; discussions on the classification of nanosystems according to their nature (lipid-based, polymer-based, metallic-based and protein-based) follows. The following sections are dedicated to diagnostic and theranostic uses, respectively, which represent an innovation in the ocular field obtained by combining dual goals in a single administration system. For its great potential, this application of fluorescent nanoparticles would experience a great development in the near future. Finally, a brief overview is dedicated to the use of fluorescent markers in clinical trials and the market in the ocular field.

Epiregulin, epigen and betacellulin antibodies and axial elongation in young guinea pigs with lens-induced myopization

Background

To examine an effect of intravitreally applied antibodies against epidermal growth factor family members, namely epiregulin, epigen and betacellulin, on ocular axial elongation.

Methods

The experimental study included 30 guinea pigs (age:3–4 weeks) which underwent bilateral lens-induced myopization and received three intraocular injections of 20 µg of epiregulin antibody, epigen antibody and betacellulin antibody in weekly intervals into their right eyes, and of phosphate-buffered saline into their left eyes. Seven days after the last injection, the animals were sacrificed. Axial length was measured by sonographic biometry.

Results

At baseline, right eyes and left eyes did not differ (all P > 0.10) in axial length in neither group, nor did the interocular difference in axial length vary between the groups (P = 0.19). During the study period, right and left eyes elongated (P < 0.001) from 8.08 ± 0.07 mm to 8.59 ± 0.06 mm and from 8.08 ± 0.07 mm to 8.66 ± 0.07 mm, respectively. The interocular difference (left eye minus right eye) in axial elongation increased significantly in all three groups (epiregulin-antibody:from 0.03 ± 0.06 mm at one week after baseline to 0.16 ± 0.08 mm at three weeks after baseline;P = 0.001); epigen-antibody group:from -0.01 ± 0.06 mm to 0.06 ± 0.08 mm;P = 0.02; betacellulin antibody group:from -0.05 ± 0.05 mm to 0.02 ± 0.04 mm;P = 0.004). Correspondingly, interocular difference in axial length increased from -0.02 ± 0.04 mm to 0.13 ± 0.06 mm in the epiregulin-antibody group (P < 0.001), and from 0.01 ± 0.05 mm to 0.07 ± 0.05 mm in the epigen-antibody group (P = 0.045). In the betacellulin-antibody group the increase (0.01 ± 0.04 mm to 0.03 ± 0.03 mm) was not significant (P = 0.24).

Conclusions

The EGF family members epiregulin, epigen and betacellulin may be associated with axial elongation in young guinea pigs, with the effect decreasing from epiregulin to epigen and to betacellulin.

The Organ of Vision and the Stomatognathic System-Review of Association Studies and Evidence-Based Discussion

The stomatognathic system is a functional complex of tissues and organs located within the oral and craniofacial cavities. The craniofacial anatomical factors and the biomechanics of the temporomandibular joints affect many systems throughout the body, including the organ of vision. However, few scientific reports have shown a relationship between the organ of vision and the stomatognathic system. The purpose of this review is to provide an overview of connections along neural, muscle-fascial, and biochemical pathways between the organ of vision and the stomatognathic system. Based on the literature presented in this review, the connections between the organ of vision and the stomatognathic system seem undeniable. Understanding the anatomical, physiological, and biochemical interrelationships may allow to explain the interactions between the mentioned systems. According to the current knowledge, it is not possible to indicate the main linking pathway; presumably, it may be a combination of several presented pathways. The awareness of this relationship among dentists, ophthalmologists, physiotherapists, and optometrists should increase for the better diagnosis and treatment of patients.

The Effect of Axial Length Elongation on Corneal Biomechanical Property

Background: To investigate the correlation between the corneal biomechanical parameter stress-strain index (SSI) and axial length (AL) in moderately elongated eye (MEE) and severely elongated eye (SEE).

Methods: This study included 117 eyes from 117 participants. Among them, 59 (50.4%) had MEE (AL<26 mm) and 58 (49.6%) had SEE (AL≥26 mm). AL was measured using Lenstar LS-900, and central corneal thickness (CCT) and anterior chamber volume (ACV) were measured using Pentacam. SSI was measured via corneal visualisation Scheimpflug technology (Corvis ST). Kolmogorov-Smirnov test, Student’s t-test, and Pearson and partial correlation analyses were used for statistical analyses.

Results: The mean (±SD) SSI was 1.08 ± 0.15 in the MEE group and 0.92 ± 0.13 in the SEE group (p < 0.01). SSI was positively correlated with age (MEE: r = 0.326, p < 0.05; SEE: r = 0.298, p < 0.05) in both groups; it was negatively correlated with AL (r = −0.476, p < 0.001) in the MEE group but not in the SEE group (p > 0.05). CCT was negatively correlated with AL (r = −0.289, p < 0.05) and ACV positively correlated with AL (r = 0.444, p < 0.001) in the MEE group. Neither CCT nor ACV was correlated with AL (p > 0.05) in the SEE group.

Conclusion: Corneal biomechanical parameter SSI, which represents the stiffness of corneal tissue, was lower in the SEE group than in the MEE group. When analyzed separately, SSI was negatively correlated with AL in the MEE group, but not in the SEE group, which may provide insight into different ocular growth patterns between lower myopia and higher myopia.

Histology of neovascular myopic macular degeneration

To assess the histological correlate of neovascular or exudative myopic macular degeneration (nMMD) in highly myopic human eyes, we examined histomorphometrically histologic sections of enucleated eyes of Caucasian patients. The study included 284 eyes (age: 61.9 ± 13.7 years; range: 24–89 years; axial length: 25.5 ± 3.1 mm; range: 20–37 mm). An nMMD was detected in 5 eyes (axial length: 29.6 ± 2.6 mm; range: 26.0–31.0 mm). All these eyes showed within or close to the nMMD a macular Bruch’s membrane (BM) defect, fibrous tissue with erythrocyte-filled blood vessels, and proliferations of irregularly pigmented and irregularly piled-up retinal pigment epithelium (RPE) cells each of which was connected with a curled-up, PAS (Periodic-Acid-Shiff)-positive membrane. The nMMD lesions were covered by proliferated RPE cells. RPE cells were not detected within the retina. In binary regression analysis, a higher nMMD prevalence was associated with a higher prevalence of macular BM defects (odds ratio: > 1000; P < 0.001), while the association with axial length was not significant (P = 0.43) in that model. After adjustment for the presence of macular BM defects, the nMMD prevalence was not associated with BM thickness (measured at the posterior pole, equator-posterior pole midpoint, equator and shortly posterior to the ora serrata) (P = 0.10; P = 0.87; P = 0.40; and P = 0.36, respectively), RPE cell layer thickness (P = 0.83; P = 0.79; P = 0.31; P = 0.38, resp.), RPE cell density (P = 0.56; P = 0.91; P = 0.47; P = 0.87, resp.), choriocapillaris thickness (P = 0.47; P = 0.93; P = 0.41; P = 0.75, resp.), and choriocapillaris density (P = 0.99; P = 0.94; P = 0.17; P = 0.97, resp.). The results suggest that nMMD is characterized by a fibrous pseudo-metaplasia of the RPE and is strongly associated with macular BM defects, without other detected histomorphometric differences in thickness or density of the RPE, BM, and choriocapillaris.

Lowering Intraocular Pressure: A Potential Approach for Controlling High Myopia Progression

High myopia is among the most common causes of vision impairment, and it is mainly characterized by abnormal elongation of the axial length, leading to pathologic changes in the ocular structures. Owing to the close relationship between high myopia and glaucoma, the association between intraocular pressure (IOP) and high myopia progression has garnered attention. However, whether lowering IOP can retard the progression of high myopia is unclear. On reviewing previous studies, we suggest that lowering IOP plays a role in progressive axial length elongation in high myopia, particularly in pathologic myopia, wherein the sclera is more remodeled. Based on the responses of the ocular layers, we further proposed the potential mechanisms. For the sclera, lowering the IOP could inhibit the activation of scleral fibroblasts and then reduce scleral remodeling, and a decrease in the scleral distending force would retard the ocular expansion like a balloon. For the choroid, lowering IOP results in an increase in choroidal blood perfusion, thereby reducing scleral hypoxia and slowing down scleral remodeling. The final effect of these pathways is slowing axial elongation and the development of scleral staphyloma. Further animal and clinical studies regarding high myopia with varied degree of IOP and the changes of choroid and sclera during IOP fluctuation in high myopia are needed to verify the role of IOP in the pathogenesis and progression of high myopia. It is hoped that this may lead to the development of a prospective treatment option to prevent and control high myopia progression.

ODTiD: Optic Nerve Head SD-OCT Image Dataset

Introduction

Optic disc tilt (ODT) or tilted optic disc is a common finding in the general population. It is due to anomalous development caused by the malclosure of the embryonic optic fissure. ODT is commonly associated with high myopia as well as other conditions. In recent days, the common method to image the optic disc (OD) is by optical coherence tomography (OCT). To the best of our knowledge, there are no datasets of ODT available in the public domain. This dataset aims to make open access raw ODT OCT images to test out new image processing segmentation algorithms.

Methods

This dataset of ODT images contains both horizontal and vertical cross-sectional images obtained using spectral-domain optical coherence tomography (SD-OCT, Cirrus 5000, Carl Zeiss Meditec Inc., Dublin, CA). The optic disc cube 200×200 program was used and all the images are aligned with the center of the optic nerve head. This dataset includes images from both clinically normal (20 eyes) and myopic subjects (101 eyes).

Results

The dataset consists of clear (121) and manually marked (121) images resulting in a total of 242 images. The age distribution for all subjects combined is 27.24 ± 9.28 (range, 11.0-69.0) years. For normal subjects mean ± SD age distribution is 32.40 ± 17.23 years. Similarly, the myopia age distribution is 26.22 ± 6.37 years. Ground truth images, ie, manually segmented by a clinical expert are provided along with other meta-data includes age, gender, laterality, refractive error classification, spherical equivalent (SE), best-corrected visual acuity (BCVA), intraocular pressure (IOP), and axial length (AXL).

Conclusion

This open, public database is online at the ICPSR website of the University of Michigan. The dataset can be used to test and validate newly developed automated segmentation algorithms.

Changes in anterior segment parameters and presence of dry eye disease in patients with acromegaly: A Sirius topography study combined with meibography

PURPOSE

To investigate anterior segment parameters (ASPs) and dry eye disease (DED), including the status of the meibomian glands, in patients with acromegaly.

METHODS

In this cross-sectional, comparative study, 36 acromegaly patients and 40 healthy sex- and age-matched controls were included. Participants received a comprehensive ophthalmological examination, including intraocular pressure measurements with Goldmann applanation tonometry (IOP_GAT) and central corneal thickness corrected intraocular pressure (IOP_CCT) measurements, and were evaluated for ASPs and DED. For ASPs, white-to-white (WTW), apical (ACT) and thinnest corneal thickness (TCT), corneal volume (CV), keratometry readings (K₁, K₂, and K_mean), anterior chamber depth (ACD) and volume (ACV), and iridocorneal angle (ICA) were obtained via Sirius topography. DED was assessed with Schirmer's test, tear breakup time (TBUT), and Ocular Surface Disease Index (OSDI) scores. Meibography scores (MSs) were obtained with the Sirius topography device.

RESULTS

Patients had higher mean IOP_GAT (P = .006), IOP_CCT (P = .01), ACT (P = .024), and TCT (P = .005) but narrower ICA (P = .014) than controls. Although Schirmer's test did not differ between the groups (P = .442), patients had higher OSDI (P < .001), higher MS (P = .001), and shorter TBUT (P = .002).

CONCLUSION

Patients with acromegaly have greater IOP, greater corneal thickness, but narrower ICA than healthy individuals, as well as DED with increased MSs, which suggests meibomian gland dysfunction.

Choroidal shift in myopic eyes in the 10-year follow-up Beijing eye study

The aim of the study was to assess longitudinal changes in the spatial relationship of the choroidal vasculature to retinal vasculature in myopic eyes. In the population-based longitudinal Beijing Eye Study in 2001/2011, we examined all highly myopic eyes with assessable fundus photographs and a randomized group of non-highly myopic. Using fundus photographs, we qualitatively assessed changes in the location of major choroidal vessels in relationship to retinal vessels. The study consisted of 85 highly myopic eyes (58 participants;age:64.8 ± 9.4 years) and 85 randomly selected non-highly myopic eyes. A choroidal shift in relationship to the retinal vessels was detected more often in the highly myopic group than the non-highly myopic group (47/85 (55%) vs 6/85 (7%); P < 0.001). In the highly myopic group, the choroidal vessel shift occurring on the disc-fovea line in 39 (44%) eyes, was similar to, or smaller than, the enlargement in gamma zone width in 26 (67%) eyes and in 11 (28%) eyes respectively. The choroidal vessel shift was larger (P = 0.002) in eyes without choroidal vessels in gamma zone than in eyes with large choroidal vessels in gamma zone. In 14 (17%) eyes, a localized centrifugal choroidal shift was observed in association with an increase in the stage of myopic maculopathy. The results suggest that highly myopic eyes show a change in the position of large choroidal vessels in relationship to retinal vessels, in association with development or enlargement of gamma zone and an increase in the stage of myopic maculopathy.

Comparison of IOL-Master 700 and IOL-Master 500 biometers in ocular biological parameters of adolescents

AIM

To compare the differences and consistency of IOL-Master 700 biometers applying swept optical coherence tomography with the conventional IOL-Master 500 applying partial coherence interference in terms of the ocular biological parameters in adolescents with ametropia.

METHODS

A total of 110 adolescents (110 eyes) with ametropia were collected, including 55 males and 55 females; age 10.69±2.81y. Ocular biological measurements were taken by IOL-Master 700 and IOL-Master 500 respectively to obtain biological parameters including axial length (AL), mean corneal anterior surface keratometry (K_m), anterior chamber depth (ACD), and horizontal corneal diameter (WTW). Paired t-test was used to compare the differences between the two instruments. The intra-group correlation coefficient (ICC) and the Bland-Altman analysis were used to evaluate the consistency of parameter measurements between the two instruments for the four biological parameters.

RESULTS

Statistical analysis showed that there was no significant difference in the K_m value measured by IOL-Master 700 and IOL-Master 500 (t=-1.644, P=0.116). The average differences of the AL, ACD, and WTW distances between the two instruments are 0.028, 0.101 and 0.064 mm respectively, and the differences are statistically significant (t=2.644, 12.505, 3.911, P<0.001). The consistency study results indicated high correlation in the measurement of AL, K_m, ACD and WTW between the two instruments (ICC=0.994, 0.873, 0.927, 0.912).

CONCLUSION

The novel biometric instrument IOL-Master 700 makes no difference with IOL-Master 500 in the measurement of K_m. There are some differences in the values of AL, ACD, and WTW. However, the two instruments show good consistency in these four biological measurements. The measured values of K_m are interchangeable between the instruments. These two types of biometrics can be used as mutual reference in consideration of that the differences in AL, ACD, and WTW measurements are not sufficient to produce clinically meaningful differences.

Multimodal Imaging Characteristics and Presumed Cause of Intrapapillary Hemorrhage with Adjacent Peripapillary Subretinal Hemorrhage

Purpose

To describe the multimodal imaging findings of intrapapillary hemorrhage with adjacent peripapillary subretinal hemorrhage (IHAPSH) and reveal the possible mechanism of this rare benign disease.

Patients and Methods

Observational study. Three eyes in three patients with intrapapillary hemorrhage with adjacent peripapillary subretinal hemorrhage were evaluated at the retina division of our institution. We describe the multimodal imaging findings including visual field examination, fundus photography, fluorescein and indocyanine green angiography (FFA&ICGA), spectral-domain optical coherence tomography (OCT), and ultrasonography.

Results

Three myopic patients with IHAPSH shared a similar clinical course and multimodal imaging appearance. The symptom was sudden dark shadows floating in the affected eye with mild visual blurring. Fundus photography showed hemorrhage in intrapapillary and subretinal, as well as optic disc bulges on the nasal side with local vitreoretinal separation in the affected eyes. OCT confirmed intrapapillary and subretinal hemorrhage with obviously elevated optic papilla in the affected eye and local vitreoretinal separation at the temporal side of optic disc together with vitreoretinal adhesion at the superonasal edge. FFA&ICGA ruled out optic drusen and neovascularization. B-ultrasonography in one case revealed optic disc bulge in the affected eye with tight traction by local detached vitreous posterior limiting membrane at the edge. The overall visual prognosis was excellent and the bleeding could be completely absorbed.

Conclusion

IHAPSH tends to appear in young women with myopia. The mechanism may be attributed to an incomplete posterior vitreous detachment (PVD), followed by a tightly vitreous-papilla adhesion and concentrated traction to the superonasal part of the tilted small optic disc.

Longitudinal Changes in Macular Optical Coherence Tomography Angiography Metrics in Primary Open-Angle Glaucoma With High Myopia: A Prospective Study

Purpose

To characterize longitudinal changes in macular microvasculature as quantified from optical coherence tomography angiography (OCTA) metrics in primary open-angle glaucoma (POAG) eyes with and without high myopia.

Methods

In total, 63 and 61 POAG eyes with and without high myopia, respectively, underwent swept-source OCTA imaging in at least four follow-up visits at an ophthalmic center, with a scanning protocol of 3- × 3-mm centered at the fovea. The foveal avascular zone (FAZ) area, FAZ circularity, and vessel density (VD) in both the superficial (SCP) and deep capillary plexuses (DCP) were measured. The rate of change in macular OCTA metrics over time was estimated using linear mixed-effects models in both groups of POAG eyes.

Results

The mean follow-up time and number of visits were 27.72 ± 8.57 months and 8.5 (8 to 13) times, and 30.95 ± 10.19 months and 10 (8‒13) times in POAG eyes with and without high myopia, respectively. VD in the DCP reduced significantly more quickly in POAG eyes with high myopia than in those without high myopia (−5.14%/year vs. −3.71%/year, P = 0.008). Moreover, lower baseline VD in the DCP was significantly associated with faster VD reduction in POAG with high myopia eyes (P < 0.001). Conversely, the VD reduction rate in the SCP, FAZ area, and FAZ circularity in both the SCP and DCP were similar in both groups (all Ps > 0.05).

Conclusions

VD in DCP reduced significantly more quickly in POAG eyes with high myopia over time. Density in the DCP reduced more quickly when baseline VD was low.

Location of Parapapillary Gamma Zone and Vertical Fovea Location. The Beijing Eye Study 2011

Purpose

To assess the spatial relationship between the locations of the parapapillary gamma zone and the fovea.

Methods

In a non-glaucomatous subgroup of the population-based Beijing Eye Study population, we measured the mean angle between the optic disc–fovea line and the horizontal (disc–fovea angle), the vertical distance of the fovea from the horizontal through the optic disc center (fovea vertical distance), and the location and width of the widest part of parapapillary gamma zone.

Results

The study included 203 individuals (203 eyes; mean axial length, 24.4 ± 1.5 mm; range, 22.03–28.87 mm). The widest gamma zone part was located most often temporal horizontally (51.7%), then inferiorly (43.8%), superiorly (2.5%), and nasally (2.0%). The disc–fovea angle (mean, 7.50° ± 4.00°; range, –6.30° to –23.25°) was significantly higher (P = 0.003; i.e., fovea located more inferiorly) in eyes with the widest gamma zone inferiorly (8.46° ± 4.37°) than in eyes with the widest gamma zone temporally (6.71° ± 3.46°) and in eyes with the widest gamma zone temporally, superiorly, or nasally combined (6.75° ± 3.53°; P = 0.003). The fovea vertical distance (mean, 0.65 ± 0.33 mm; range, –0.20 to 1.67 mm) was longer (P = 0.001; i.e., fovea located more inferiorly) in eyes with the widest gamma zone inferiorly (0.73 ± 0.33 mm) than in eyes with the widest gamma zone temporally (0.58 ± 0.30 mm) and in eyes with a temporal, superior, or nasal gamma zone combined (0.58 ± 0.31 mm; P = 0.001). The fovea vertical distance increased (multivariate analysis) with the widest gamma zone location inferiorly (β = 0.25; P = 0.001) and wider width of the gamma zone (β = 0.19; P = 0.01).

Conclusions

An inferior fovea location is associated with a wider inferior gamma zone and vice versa, supporting the notion of an inferior shifting of Bruch's membrane as the cause for an inferior gamma zone.

Intraocular epidermal growth factor concentration, axial length, and high axial myopia

Purpose

Various molecules such as dopamine have been found to be associated with axial elongation in experimental studies. Here, we examined whether intraocular EGF is associated with axial length in myopic patients.

Methods

The hospital-based investigation included patients of European descent without optic nerve, retinal, or macular diseases except for myopic maculopathy. Using aqueous humor samples collected during surgery, the EGF concentration was examined applying a cytometric bead array. High myopia was defined by an axial length of ≥ 27.0 mm.

Results

The study included a non-highly myopic group of 11 patients (mean age, 72.9 ± 10.8 years; mean axial length, 24.3 ± 1.1 mm) and a highly myopic group of three patients (age, 81.11 ± 12.3 years; axial length, 29.5 ± 1.3 mm), with one of them having pathologic myopic maculopathy. In multivariable linear regression analysis, higher EGF concentration was correlated with the highly myopic versus non-highly myopic group (beta, 1.24; non-standardized correlation coefficient B, 6.24; 95% confidence interval (CI), 0.10,12.4;P = 0.047) after adjusting for axial length. The amount of intraocular EGF was significantly higher in the highly myopic group than in the non-highly myopic group (89.1 ± 40.8 pg versus 34.1 ± 13.2 pg; P = 0.005), and it was highest in the eye with myopic maculopathy (135 pg).

Conclusions

The intraocular amount of EGF is higher in highly myopic versus non-highly myopic eyes.

Axial length and its relationship to refractive error in Chinese university students

PURPOSE

To investigate the relationship between axial length (AL) and refractive error (RE).

METHODS

Participants comprised Chinese university students. In total, 894 eyes with low hyperopia to emmetropia (-0.50D ≤ spherical equivalent (SE) ≤ +2.00D), and 1007 eyes with moderate to high myopia (-11.00D ≤ SE ≤ -4.00D) were analyzed. Cycloplegic RE and AL were measured with an autorefractor and IOL Master respectively. The association between AL and RE was evaluated by linear regression. Furthermore, differences in the mean AL, as well as the correlation between AL and ocular refraction, were evaluated according to SE, sex, and age.

RESULTS

In both the moderate to high myopia and low hyperopia to emmetropia groups, mean AL was significantly longer in men (26.48 mm, confidence interval (CI) 26.41-26.56 mm; 23.82 mm, CI: 23.76-23.88 mm, respectively) than in women (25.78 mm, CI: 25.71-25.86 mm; 23.25 mm, CI: 23.17-23.33 mm, respectively). For both men and women, mean AL significantly differed among four SE groups (+0.50D < SE ≤ +2.00D, -0.50D ≤ SE ≤ +0.50D, -4.00D ≤ SE ≤ -6.00D, SE < -6.00D, P < 0.001). The correlation coefficient between AL and ocular refraction was -0.318 and -0.277 in male and female participants, respectively, with low hyperopia to emmetropia (-0.50D ≤ SE ≤ +2.00D), and -0.545 and -0.437 in male and female participants, respectively, with moderate to high myopia (-11.00D ≤ SE ≤ -4.00D). There were no age-related effects on SE (P = 0.714) or AL (P = 0.952).

CONCLUSIONS

Ocular refraction is negatively correlated with AL in Chinese university students. The correlation coefficient is greater in those with moderate to high myopia than in those with low hyperopia to emmetropia. Furthermore, the AL is longer in men than in women.

IMI 2021 Yearly Digest

Purpose

The International Myopia Institute (IMI) Yearly Digest highlights new research considered to be of importance since the publication of the first series of IMI white papers.

Methods

A literature search was conducted for articles on myopia between 2019 and mid-2020 to inform definitions and classifications, experimental models, genetics, interventions, clinical trials, and clinical management. Conference abstracts from key meetings in the same period were also considered.

Results

One thousand articles on myopia have been published between 2019 and mid-2020. Key advances include the use of the definition of premyopia in studies currently under way to test interventions in myopia, new definitions in the field of pathologic myopia, the role of new pharmacologic treatments in experimental models such as intraocular pressure-lowering latanoprost, a large meta-analysis of refractive error identifying 336 new genetic loci, new clinical interventions such as the defocus incorporated multisegment spectacles and combination therapy with low-dose atropine and orthokeratology (OK), normative standards in refractive error, the ethical dilemma of a placebo control group when myopia control treatments are established, reporting the physical metric of myopia reduction versus a percentage reduction, comparison of the risk of pediatric OK wear with risk of vision impairment in myopia, the justification of preventing myopic and axial length increase versus quality of life, and future vision loss.

Conclusions

Large amounts of research in myopia have been published since the IMI 2019 white papers were released. The yearly digest serves to highlight the latest research and advances in myopia.

Elongation of the disc-fovea distance and retinal vessel straightening in high myopia in a 10-year follow-up of the Beijing eye study

To assess changes in the disc-fovea distance (DFD) in highly myopic eyes in a 10-year population-based follow-up study. The case control study included all highly myopic eyes (myopic refractive error ≥ − 6.0 diopters or axial length ≥ 26.0 mm) and a randomized group of non-highly myopic eyes examined in the population-based Beijing Eye Study 2001 and 2011. Using fundus photographs and optical coherence tomographic images, we assessed changes in DFD, parapapillary gamma zone, angle kappa (angle between the temporal arterial arcades), and course of papillo-macular retinal vessels. The study included 89 highly myopic eyes and 86 non-highly myopic eyes. DFD elongation, gamma zone widening, angle kappa decrease and straightening of papillo-macular retinal vessels were detected more often (all P < 0.001) in the highly myopic group than in the non-highly myopic group (63/89 versus 9/86;75/89 versus 18/86;61/89 versus 9/86; and 58/89 versus 7/86,respectively). Gamma zone enlargement, angle kappa reduction and papillo-macular retinal vessel straightening were significantly (all P < 0.001) associated with DFD elongation. The length of macular Bruch’s membrane on the disc-fovea line and the vertical distance between the temporal arterial arcade did not change during follow-up. DFD elongation (10-year incidence 70.8% in highly myopic eyes) was associated with gamma zone enlargement, while macular Bruch’s membrane length remained unchanged. It supports the notion of a temporal shift of an otherwise stable posterior Bruch’s membrane in axially elongated eyes. Straightening of the papillo-macular vessels with increasing gamma zone width suggests a coincident stretching of the papillo-macular retinal nerve fibers and inner limiting membrane.