Retinal and Choroidal Thickness in Patients with High Myopia without Maculopathy

Aging in Ocular Blood Vessels: Molecular Insights and the Role of Oxidative Stress

Acknowledged as a significant pathogenetic driver for numerous diseases, aging has become a focal point in addressing the profound changes associated with increasing human life expectancy, posing a critical concern for global public health. Emerging evidence suggests that factors influencing vascular aging extend their impact to choroidal and retinal blood vessels. The objective of this work is to provide a comprehensive overview of the impact of vascular aging on ocular blood vessels and related diseases. Additionally, this study aims to illuminate molecular insights contributing to vascular cell aging, with a particular emphasis on the choroid and retina. Moreover, innovative molecular targets operating within the domain of ocular vascular aging are presented and discussed.

Myopia, Sodium Chloride, and Vitreous Fluid Imbalance: A Nutritional Epidemiology Perspective

Theories of myopia etiology based on near work and lack of outdoor exposure have had inconsistent support and have not prevented the rising prevalence of global myopia. New scientific theories in the cause and prevention of myopia are needed. Myopia prevalence is low in native people consuming traditional diets lacking in sodium chloride, and nutritional epidemiological evidence supports the association of rising myopia prevalence with dietary sodium intake. East Asian populations have among the highest rates of myopia associated with high dietary sodium. Similar associations of sodium and rising myopia prevalence were observed in the United States in the late 20th century. The present perspective synthesizes nutritional epidemiology evidence with pathophysiological concepts and proposes that axial myopia occurs from increased fluid retention in the vitreous of the eye, induced by dietary sodium chloride intake. Salt disturbs ionic permeability of retinal membranes, increases the osmotic gradient flow of fluid into the vitreous, and stretches ocular tissue during axial elongation. Based on the present nutritional epidemiology evidence, experimental research should investigate the effect of sodium chloride as the cause of myopia, and clinical research should test a very low-salt diet in myopia correction and prevention.

Age-Related Alterations of the Macular Choroid in Healthy Eyes Assessed by Swept-Source Optical Coherence Tomography Angiography

OBJECTIVE

To analyze age-related changes in the choroid in healthy eyes using swept-source optical coherence tomography angiography (SS-OCTA).

PATIENTS AND METHODS

This was a cross-sectional, prospective, observational study enrolling 222 eyes of 116 healthy participants. SS-OCTA images were captured using the PLEX Elite 9000 (Carl Zeiss Meditec) with a 6 x 6 mm pattern centered on the fovea. Subfoveal choroidal thickness (CT) and choroidal volume (CV) were generated automatically through manufacturer tools available in the Advanced Retinal Imaging (ARI) hub network. Choroidal vascularity index (CVI) and choriocapillaris flow deficits (CCFD) were computed using ImageJ.

RESULTS

CV was found to be significantly higher in women than men. Overall, there was a significant positive correlation between CVI and CCFD, and a significant negative correlation between CT and CV with age. The relationship, however, was more complex, as a decade-wise analysis showed that CT and CV increased until the second decade, followed by a decrease until the sixth decade, and then an increase again in the seventh and eighth decades. CVI was highest in the seventh decade. In contrast, CCFD increased consistently with age and in all the Early Treatment of Diabetic Retinopathy Study (ETDRS) rings.

CONCLUSION

The choroidal blood flow and its thickness reduces as the age advances. While the choroidal flow deficits show a consistent increase with age and the distance from the foveal center, the relationship of other parameters with age is more complex. Having a normative database from healthy subjects is imperative for understanding the changes taking place in diseased states. Choroidal parameters can show significant variations with age. These differences are not uniform or consistent with age, highlighting the importance of a normative reference database to assess the significance of choroidal alterations associated with disease. [Ophthalmic Surg Lasers Imaging Retina 2023;54:526-534.].

SubFoveal Choroidal Imaging in High Myopic Nepalese Cohort

Purpose

Evidence suggests that choroid is thinner in myopes as compared to nonmyopes. However, choroidal thickness varies with the refractive error, age, axial length, and ethnicity. The purpose of this study was to determine the subfoveal choroidal thickness (SFCT) in high myopic Nepalese subjects and to investigate its association with the mean spherical equivalent refractive error (MSE), axial length, and age.

Methods

Ninety-two eyes of 92 high myopic subjects (MSE ≤ -6 diopters) and 83 eyes of 83 emmetropic subjects (MSE: 0.00 Diopters) were included in the study. SFCT was assessed using spectral domain optical coherence tomography, and the axial length was measured using partial coherence interferometry. SFCT was measured manually using the inbuilt tool within the imaging software.

Results

SFCT in the high myopic subjects was significantly thinner (mean ± SD: 224.17 ± 68.91 μm) as compared to the emmetropic subjects (353.24 ± 65.63 μm) (mean difference, 127.76 ± 130.80 μm, and p < 0.001). In high myopic subjects, there was a significant negative correlation of choroidal thickness with the axial length (rho = -0.75; p < 0.001) and MSE (rho = -0.404; p < 0.01). Regression analysis demonstrated a decrease of choroidal thickness by 40.32 μm (p < 0.001) for every 1 millimeter increase in the axial length and by 11.65 μm (p < 0.001) for every 1 diopter increase in the MSE.

Conclusion

High myopic Nepalese subjects had significantly thinner choroid as compared to emmetropes. The MSE and axial length were inversely correlated with the SFCT. Age had no effect on SFCT in this study. These findings may have implications in interpreting choroidal thickness values in clinical and epidemiological studies in myopes, especially in the south Asian population.

Effect of High Myopia on Delayed Absorption of Subretinal Fluid after Scleral Buckling Surgery

This study compared the absorption of subretinal fluid (SRF) in patients with rhegmatogenous retinal detachment (RRD) with and without high myopia after scleral buckling (SB) and investigated the effect of high myopia on SRF absorption. This retrospective study included patients with primary macula-off RRD grouped according to myopia and age. The optical coherence tomography (OCT) and OCT angiography indicators included subretinal fluid height (SRFH), subfoveal choroidal thickness (SFCT), and choroidal capillary blood flow density (CCFD) measured regularly. The presence of SRF 3 months after surgery was defined as delayed absorption. Overall, 90 eyes of 89 patients were enrolled, and 46 eyes (51.11%) had high myopia. In 43 eyes (47.78%), SRF absorption was delayed. There was no significant difference in SRF absorption after SB between the high and non-high myopia groups; younger patients (<35 years) had a higher probability of delayed absorption (p < 0.05). The SFCT in high myopia was significantly thinner than that in the non-high myopia group (p < 0.05); SFCT and SRFH were positively correlated (rs = 0.275, p = 0.002), and there was a significant difference between the average CCFD with and without SRF (p < 0.05). High myopia had no significant effect on SRF absorption after SB.

Retinal and Choroidal Thickness in Myopic Young Adults

The retinal and the choroidal thickness were measured at four locations along the horizontal direction (foveola, one nasal to the fovea and two temporal) in a group of 43 young adults (mean age: 27.1 ± 3.9 years), with ocular refraction ranging from emmetropia to high myopia (0 to −10D). Thickness values were obtained from OCT images centered at the foveal depression. The retinal thickness exhibited a correlation with refraction at all eccentricities but not at the fovea. When different subgroups of refraction were considered, the analysis of such correlations indicated that only the retinal thickness in the group of high myopia (refraction ≤ −6D) was statistically different from the other two groups (emmetropes: [−0.5, 0] D, and myopes: (−6, −0.5) D). No significant differences were found between emmetropic and myopic groups. In contrast to the retina, the choroidal thickness exhibited a significant correlation with refraction at the fovea, although such dependency only stood for high myopes (the choroid of myopes and emmetropes exhibited similar thickness). Correlation with refraction was also found at the nasal location, arising between emmetropic and high myopia groups. Other choroidal locations among groups did not exhibit relationship with the refraction. It is concluded that the differences in the choroid and retina thickness along the horizontal meridian as a function of refraction do not characterize the onset and progression of myopia at early stages, since they only manifest in the group of high myopia.

Examination of Macular Retina and Choroidal Thickness in High Myopic Amblyopia Using Spectral-Domain Optical Coherence Tomography

Purpose

The aim of this study was to investigate changes in the retinal and choroidal thickness between high myopic amblyopia (HMA), low myopia (LM), moderate myopia (MM), high myopia (HM), and normal group (NG) using a spectral-domain optical coherence tomography (SD-OCT).

Materials and Methods

A total of 75 Chinese children (128 eyes; mean age 10.5 years) were recruited. Retinal thickness (RT) and choroidal thickness (CT) were measured at different locations including subfoveal (SF), and at 0.5 mm/1.0 mm/1.5 mm/2.0 mm/2.5 mm/3.0 mm to the fovea in superior, nasal, inferior, and temporal sectors using enhanced depth imaging (EDI) system of SD-OCT. Axial length (AL), best-corrected visual acuity (BCVA), and refraction errors were also collected.

Results

No significant differences were found in subfoveal retinal thickness (SFRT). Moreover, a significantly thinner subfoveal choroidal thickness (SFCT) was found in HMA compared to NG, LM, and MM, but not compared to HM. RT at 0.5 mm to fovea, HMA was significantly thinner compared to LM and MM in the three sectors (superior, inferior, and temporal). Nevertheless, no significant differences were found compared to NG and HM. CT at 0.5 mm to fovea, HMA was the significantly thinnest in all four sectors compared to NG, LM, and MM. RT at 1.0 mm/1.5 mm/2.0 mm/2.5 mm/3.0 mm to fovea, HMA was thinner compared to NG, LM, and MM. CT at 1.0 mm/1.5 mm/2.0 mm/2.5 mm/3.0 mm to fovea, HMA was thinner compared to NG, LM, and MM. At the superior and inferior sectors, HMA showed to be statistically thinner compared with HM. Moreover, SFCT in the HMA, HM, and NG were negatively correlated with AL.

Conclusions

Thinner retina and choroidal tissue appear to be related to HMA, and thus can be used as useful parameters for discovering the underlying mechanisms of the disease.

Choroidal Thickness in Correlation with Axial Length and Myopia Degree

Background: Myopia is a condition in which the visual images come to a focus in front of the retina of the eye. This disease is a major cause of visual disability, which presents in 108 million persons globally. Purpose: This study aims to determine the relationship between the degree of myopia, the axial length, and the choroidal thickness (CT). Methods: This is an observational analytical study that made use of a cross-sectional design. A total of 59 participants with refractive errors underwent treatment at Hasanuddin University Hospital and 116 eyes were measured and analyzed. The choroidal thickness was measured using the Enhance Depth Imaging OCT (EDI-OCT) tool, which is divided into nine observational areas. Furthermore, all data obtained were compared using statistical analysis, such as the one-way ANOVA and Pearson correlation test (p < 0.05). Results: There was a significant relationship between the choroidal thickness with axial length (p < 0.05) and myopia degrees (p < 0.05). Conclusions: The thickness of the choroid decreases with an increase in the axial length and degree of myopia, which further indicates that the higher the myopia degree, the thinner the choroidal vasculature.

The Relationship Between Choroidal and Photoreceptor Layer Thickness With Visual Acuity in Highly Myopic Eyes

Purpose

The aim of this study was to evaluate the choroidal and photoreceptor thickness in highly myopic eyes and its correlation with visual acuity.

Methods

This is a cross-sectional, observational study involving 57 eyes of 57 highly myopic subjects [spherical equivalent ≥ –6 diopters (D) or axial length ≥ 26 mm] seen in a tertiary institutional center. Eyes with any clinical evidence of maculopathy or amblyopia were excluded. All subjects underwent a refraction assessment, visual acuity, axial length measurement using the IOL Master, and full ocular assessment. Eyes were imaged using Spectralis Optical Coherence Tomography by one experienced operator. Two independent investigators manually measured subfoveal choroidal thickness (SFCT) and foveal photoreceptor thickness (FPT).

Results

The mean SFCT was 195.88 ± 87.63 μm (range: 32–373) and mean FPT was 96.68 ± 11.23 μm (range: 67–100), after correction for ocular magnification. The best corrected visual acuity (BCVA) in LogMAR was negatively correlated with SFCT (r = –0.510, p = 0.001) and FPT (r = –0.397, p = 0.002) and positively correlated with age (r = 0.418, p = 0.001) and axial length (r = 0.551, p = 0.001). Multiple linear regression analysis showed that age, axial length, and corrected FPT were significant risk factors for poorer BCVA (p = 0.021, &lt; 0.001, and 0.02, respectively).

Conclusion

FPT, age, and axial length are significant moderate predictive factors for poorer visual acuity in highly myopic eyes without myopic maculopathy. Thinner SFCT does not translate into poorer vision.

Associations of refractive errors and retinal changes measured by optical coherence tomography: A systematic review and meta-analysis

Studies reporting alteration in retinal thickness using optical coherence tomography (OCT) have been performed in different populations with various degrees of refractive error, producing inconsistent results. Therefore, we performed a meta-analysis to evaluate the alterations in retinal OCT measurements in myopic and hyperopic patients compared to controls. Evaluation of different retinal layers' thickness may have significance for developing novel approaches for preventing, diagnosing, and treating refractive errors and their complications. We searched PubMed and EMBASE to identify articles that reported OCT measurements of different retinal layers and regions, including macular, foveal, parafoveal, perifoveal, foveolar, ganglion cell complex (GCC), retinal nerve fiber layer (RNFL), peripapillary retinal nerve fiber layer (pRNFL), and ganglion cell and inner plexiform layer (GC-IPL) thickness in addition to macular volume, and optic disc area in myopes and hyperopes comparing their differences with controls. We applied either a fixed-effects or random-effects model for the meta-analysis of these differences based on the assessed heterogeneity level. Furthermore, subgroup analyses and metaregression, as well as publication bias and quality assessment, were conducted for the eligible studies. Forty-seven studies with a total of 12223 eyes, including 8600 cases and 3623 non-cases, are included in this meta-analysis. Our results showed that, in comparison to controls, highly myopic eyes had a significantly lower value for mean macular thickness, macular GCC, macular GC-IPL, parafoveal, perifoveal, foveal, foveolar, RNFL, and pRNFL thickness. Compared to controls, moderately myopic eyes showed a significantly thinner mean macular GCC layer and pRNFL. On the other hand, hyperopic eyes had significantly thicker average pRNFL than controls. Several other significant differences were also observed in various regional analyses. The findings of the current study affirm the retinal OCT measurement differences between myopic and hyperopic eyes compared to controls, emphasizing OCT measurements' advantages as potential biomarkers of ocular pathologies.

Increased Choroidal Blood Perfusion Can Inhibit Form Deprivation Myopia in Guinea Pigs

Purpose

In guinea pigs, choroidal thickness (ChT) and choroidal blood perfusion (ChBP) simultaneously decrease in experimental myopia, and both increase during recovery. However, the causal relationship between ChBP and myopia requires further investigation. In this study, we examined the changes of ChBP with three different antimyopia treatments. We also actively increased ChBP to examine the direct effect on myopia development in guinea pigs.

Methods

Experiment 1: Guinea pigs wore occluders on the right eye for two weeks to induce form-deprivation myopia (FDM). Simultaneously they received daily antimyopia treatments: peribulbar injections of atropine or apomorphine or exposure to intense light. Experiment 2: The vasodilator prazosin was injected daily into the form-deprivation eyes to increase ChBP during the two-week induction of FDM. Other FDM animals received appropriate control treatments. Changes in refraction, axial length, ChBP, ChT, and hypoxia-labeled pimonidazole adducts in the sclera were measured.

Results

The antimyopia treatments atropine, apomorphine, and intense light all significantly inhibited myopia development and the decrease in ChBP. The treatments also reduced scleral hypoxia, as indicated by the decrease in hypoxic signals. Furthermore, actively increasing ChBP with prazosin inhibited the progression of myopia, as well as the increase in axial length and scleral hypoxia.

Conclusions

Our data strongly indicate that increased ChBP attenuates scleral hypoxia, and thereby inhibits the development of myopia. Thus ChBP may be a promising target for myopia retardation. As such, it can serve as an immediate predictor of myopia development as well as a long-term marker of it.

Axial length shortening in a myopic child with anisometropic amblyopia after wearing violet light-transmitting eyeglasses for 2 years

PURPOSE

To report a case in which the axial length (AL) shortened and the choroid thickened due to the use of violet light-transmitting eyeglasses.

OBSERVATIONS

A 4-year-old boy with high myopia was referred to Keio University Hospital. He was prescribed standard eyeglasses. Six months after the first visit, his best-corrected visual acuities were 1.2 and 0.4 in the right and left eyes, respectively, with the standard eyeglasses, and he was diagnosed with anisometropic amblyopia. The right eye then was patched for 6 hours daily during the daytime. Because of the availability of violet light-transmitting eyeglasses, we changed the eyeglasses and instructed his parents to have him engage in outdoor activities for over 2 hours daily to be exposed to sufficient violet light. As a result, the violet light entered his left eye and minimal violet light entered his right eye. The changes in the ALs, choroidal thicknesses, and cycloplegic objective refractions in the right and left eyes during 2 years of wearing violet light-transmitting eyeglasses were +0.85 and -0.20 mm, +4.9 and + 115.7 μm, and -1.02 and + 1.88 D, respectively.

CONCLUSIONS AND IMPORTANCE

We successfully described a case in which the myopia improved, the AL shortened, and the choroid thickened after using violet light-transmitting eyeglasses.

Choroidal thickness predicts progression of myopic maculopathy in high myopes: a 2-year longitudinal study

AIM

To prospectively determine the impact of choroidal thickness (CT) on the myopic maculopathy progression.

METHODS

This is a prospective, longitudinal, observational study. In total, 434 participants aged 7-70 years with bilateral high myopia (≤-6 D spherical error, range, -6 to -27.0 D) completed follow-up visits for 2 years. The baseline CT centred on the fovea was measured using a swept-source optical coherence tomography (OCT). Myopic maculopathy progression was determined by fundus photography. Logistic model was used to examine the impact of CT at baseline on the myopic maculopathy progression. Likelihood ratio test was adopted for model comparison.

RESULTS

The mean baseline age, spherical equivalence and subfoveal CT (SFCT) of the participants were 23.2±12.5 years, -10.50±3.18 D and 153.20±72.76 μm, respectively. Over 2-year's follow-up, 74 of 434 eyes (17.1%) had myopic maculopathy progression. Baseline SFCT was thinner in eyes with myopic maculopathy progression than those without (67.26±37.67 μm vs 170.95±65.45 μm; mean difference, 99.31 μm; 95% CI 83.61 to 115.01 μm; p<0.001). The same patterns of differences were observed in 7-18 years, 19-39 years and 40-70 years. In multivariate logistic regression model, SFCT was a significant risk factor (adjusted OR=0.97, p<0.005) when age, gender, axial length and baseline myopic maculopathy category were adjusted for. The addition of SFCT significantly improved the predictive discrimination of myopic maculopathy progression in comparison with that included established risk factors alone (area under the receiver operating characteristic curve, 0.899 vs 0.942, p<0.001).

CONCLUSION

CT is an independent predictor for myopic maculopathy progression.

Schlemm Canal and Trabecular Meshwork Features in Highly Myopic Eyes With Early Intraocular Pressure Elevation After Cataract Surgery

PURPOSE

To investigate the morphologic features of the Schlemm canal and trabecular meshwork in highly myopic eyes with early intraocular pressure (IOP) elevation after cataract surgery.

DESIGN

Retrospective case-control study.

METHODS

Eighty-eight highly myopic eyes of 88 patients after uneventful cataract surgery were included, 31 of which had early postoperative IOP elevation and 57 of which did not. The morphologic features of the Schlemm canal and trabecular meshwork, collected with swept-source optical coherence tomography before surgery, were reviewed. Backwards stepwise multiple linear regression was used to investigate the anatomic risk factors for early IOP elevation in highly myopic eyes.

RESULTS

Highly myopic eyes with early postoperative IOP elevation had smaller Schlemm canal vertical diameter and area, as well as smaller trabecular meshwork thickness and width, in each quadrant than the non-elevation group. There was no significant difference in Schlemm canal horizontal diameter between the IOP elevation and non-elevation groups. In the highly myopic eyes, average Schlemm canal vertical diameter, Schlemm canal area, trabecular meshwork thickness, and width were all correlated negatively with the IOP elevation. A multivariate analysis showed that average Schlemm canal vertical diameter (β = -0.262, P = .004) and trabecular meshwork thickness (β = -0.173, P < .001) were significantly associated with early transient IOP elevation in highly myopic cataract eyes.

CONCLUSIONS

A smaller vertical diameter of Schlemm canal and a thinner trabecular meshwork are 2 anatomic risk factors for early IOP elevation after cataract surgery in highly myopic eyes.

Myopia and Regional Variations in Retinal Thickness in Healthy Eyes

Purpose

To investigate the effects of refraction on retinal thickness measurements at different locations and layers in healthy eyes of Saudi participants.

Methods

Thirty-six randomly selected adults aged 27.0 ± 5.7 years who attended a Riyadh hospital from 2016 to 2017 were categorized into three groups: non-myopic (spherical equivalent refraction [SER], +1.00 to –0.50 diopters [D]), low myopic (SER, –0.75 to –3.00D), and moderate to high myopic (SER ≤ –3.25D). Full, inner, and outer retinal thicknesses were measured at nine locations by spectral-domain stratus optical coherence tomography (Optovue Inc., Fremont, CA, USA) and were compared according to refractive group and sex.

Results

The mean SERs for the non-myopia, low myopia, and moderate to high myopia groups were 0.2 ± 0.6, –1.5 ± 0.5, and –7.5 ± 1.9 D, respectively. Refractive error, but not sex, had significant effects on the retinal layer thickness measurements at different locations (P < 0.05). The parafoveal and outer retinal layers were significantly thicker than the perifoveal and inner retina layers in all groups (P < 0.05). The full foveal thickness was higher and the full parafoveal and perifoveal regions were thinner in moderate to high myopic eyes than in the non-myopic eyes (P < 0.05), but were similar to those in the low myopic eyes (P > 0.05). The foveal thicknesses measured in the inner and outer layers of the retina were higher but the thicknesses measured at the inner and outer layers of the parafoveal and perifoveal regions were lower in moderate to high myopic eyes.

Conclusion

There were regional differences in the retinal layer thicknesses of healthy Saudi eyes, which was dependent on the central refractions. This is important when interpreting retinal nerve fiber layer thicknesses in myopia and disease management in Saudi participants.

Ocular Biometric Diurnal Rhythms in Emmetropic and Myopic Adults

Purpose

To investigate diurnal variations in anterior and posterior segment biometry and assess differences between emmetropic and myopic adults.

Methods

Healthy subjects (n = 42, 23–41 years old) underwent biometry and spectral-domain optical coherence tomography imaging (SD-OCT) every 4 hours for 24 hours. Subjects were in darkness from 11:00 PM to 7:00 AM. Central corneal thickness, corneal power, anterior chamber depth, lens thickness, vitreous chamber depth, and axial length were measured. Thicknesses of the total retina, photoreceptor outer segments + RPE, photoreceptor inner segments, and choroid over a 6-mm annulus were determined.

Results

All parameters except anterior chamber depth demonstrated significant diurnal variations, with no refractive error differences. Amplitude of choroid diurnal variation correlated with axial length (P = 0.05). Amplitude of axial length variation (35.71 ± 19.40 μm) was in antiphase to choroid variation (25.65 ± 2.01 μm, P < 0.001). The central 1-mm retina underwent variation of 5.03 ± 0.23 μm with a peak at 12 hours (P < 0.001), whereas photoreceptor outer segment + RPE thickness peaked at 4 hours and inner segment thickness peaked at 16 hours. Diurnal variations in retina and choroid were observed in the 3- and 6-mm annuli.

Conclusions

Diurnal rhythms in anterior and posterior segment biometry were observed over 24 hours in adults. Differences in baseline parameters were found between refractive error groups, and choroid diurnal variation correlated with axial length. The retina and choroid exhibited diurnal thickness variations in foveal and parafoveal regions.