Myopia-related optic disc and retinal changes in adolescent children from singapore

Lamina Cribrosa Curvature in Healthy Korean Eyes

Given that posterior bowing of the lamina cribrosa (LC) is a principle event in the development of glaucomatous damage, assessment of the LC morphology may have clinical utility in diagnosing and managing glaucoma patients. LC curvature has been suggested as an index to evaluate the LC morphology. To apply LC morphology in clinical practice, it is necessary to know normal profiles of LC curvature in healthy population. This study was performed to investigate the characteristics of LC curvature in healthy eyes using enhanced depth imaging spectral-domain optical coherence tomography in a total of 250 eyes of 125 healthy Korean subjects. The lamina cribrosa curvature index (LCCI) values at seven locations spaced equidistantly across the vertical optic disc diameter were measured on serial horizontal B-scan images. The mean value of the seven measurements was defined as the average LCCI. The average LCCI was 7.46 ± 1.22 (range, 4.29–10.48) and did not differ significantly between the right and left eyes. There was a strong inter-eye correlation within subjects. LCCI was significantly larger in eyes with shorter axial length (P < 0.001). The observed range of LCCI in healthy subjects may be used as a reference for evaluating LC curvature in glaucomatous eyes.

Imaging in myopia: potential biomarkers, current challenges and future developments

Myopia is rapidly increasing in Asia and around the world, while it is recognised that complications from high myopia may cause significant visual impairment. Thus, imaging the myopic eye is important for the diagnosis of sight-threatening complications, monitoring of disease progression and evaluation of treatments. For example, recent advances in high-resolution imaging using optical coherence tomography may delineate early myopic macula pathology, optical coherence tomography angiography may aid early choroidal neovascularisation detection, while multimodal imaging is important for monitoring treatment response. However, imaging the eye with high myopia accurately has its challenges and limitations, which are important for clinicians to understand in order to choose the best imaging modality and interpret the images accurately. In this review, we present the current imaging modalities available from the anterior to posterior segment of the myopic eye, including the optic nerve. We summarise the clinical indications, image interpretation and future developments that may overcome current technological limitations. We also discuss potential biomarkers for myopic progression or development of complications, including basement membrane defects, and choroidal atrophy or choroidal thickness measurements. Finally, we present future developments in the field of myopia imaging, such as photoacoustic imaging and corneal or scleral biomechanics, which may lead to innovative treatment modalities for myopia.

Relationship between the Vertical Asymmetry of the Posterior Pole of the Eye and the Visual Field Damage in Glaucomatous Eyes

PURPOSE

This study investigated the relationship between the shape of the posterior pole of the eye and the vertical asymmetry of visual field (VF) damage in glaucomatous eyes.

DESIGN

Cross-sectional study.

PARTICIPANTS

A total of 83 eyes of 43 patients with open-angle glaucoma.

METHODS

The VF was measured using the Humphrey 24-2 or 30-2 Swedish Interactive Thresholding Algorithm (SITA) standard. The vertical asymmetry of VF damage was defined as the difference between the mean total deviation (mTD) values of the superior and inferior hemi-retinas. This difference was calculated for the hemifield, central, middle, and peripheral areas. A vertical cross-sectional image of the macula was obtained, and the magnitudes of superior and inferior retinal tilt (RT) were calculated as the difference between the lower margins of the retinal pigment epithelium (RPE) at the fovea and at a location 2 mm superior or inferior to the RPE. The RT asymmetry was defined as the difference between the inferior and superior RT. Data were analyzed using a multivariate linear mixed model.

MAIN OUTCOME MEASURES

The relationship between mTD asymmetry (hemifield, central, middle, and peripheral) and both RT asymmetry and other factors (intraocular pressure, axial length, corneal radius, age, gender, mean deviation, refraction, and visual acuity) was assessed.

RESULTS

The inferior RT was significantly larger than the superior RT (P < 0.001). Hemifield mTD asymmetry was related to RT asymmetry (P = 0.017). These relationships were significant in the middle (P = 0.029) and peripheral areas (P = 0.023), but not in the central area (P = 0.40). Other factors were not related to mTD asymmetry.

CONCLUSIONS

Vertical asymmetry of the posterior pole was related to the vertical asymmetry of glaucomatous VF damage.

Lamina Cribrosa Morphology in Glaucomatous Eyes with Hemifield Defect in a Korean Population

PURPOSE

To compare regional variations in lamina cribrosa (LC) curvature and depth between healthy eyes (group 1) and naïve eyes with primary open-angle glaucoma (POAG) having superior (group 2), inferior (group 3), and both (group 4) hemifield retinal nerve fiber layer (RNFL) defects.

DESIGN

Cross-sectional study.

PARTICIPANTS

Each group consisted of 39 eyes of 39 Korean patients who were matched for age, sex, and axial length.

METHODS

The LC curvature index (LCCI) and LC depth (LCD) were measured in B-scan images obtained using enhanced depth imaging OCT at 7 locations spaced equidistantly across the vertical optic disc diameter. Superior and inferior LCCI and LCD were compared by calculating the superior-to-inferior (Sup/Inf) ratios.

MAIN OUTCOME MEASURES

Comparisons of LCCI, LCD, and Sup/Inf ratio among the 4 groups.

RESULTS

Compared with healthy eyes (group 1), LCCIs were larger at the superior and middle planes in group 2, at the inferior and middle planes in group 3, and at all planes in group 4 (P ≤ 0.003). The LCD showed similar results, but there was no difference in superior planes between groups 1 and 2. The Sup/Inf ratio of LCCI differed significantly between groups 1 (1.03) and 2 (1.20), groups 1 and 3 (0.79), groups 2 and 3, groups 2 and 4 (0.96), and groups 3 and 4 (all P < 0.001), but not between groups 1 and 4 (P = 0.273). The Sup/Inf ratio of LCD differed only between groups 2 and 3 (P = 0.002).

CONCLUSIONS

Eyes with POAG showed regional differences in LC morphology, corresponding with the location of RNFL defects. The regional variations in LCCI suggest that LC morphology in POAG would be better assessed on a regional basis than by a global index.

Development of a deep residual learning algorithm to screen for glaucoma from fundus photography

The Purpose of the study was to develop a deep residual learning algorithm to screen for glaucoma from fundus photography and measure its diagnostic performance compared to Residents in Ophthalmology. A training dataset consisted of 1,364 color fundus photographs with glaucomatous indications and 1,768 color fundus photographs without glaucomatous features. A testing dataset consisted of 60 eyes of 60 glaucoma patients and 50 eyes of 50 normal subjects. Using the training dataset, a deep learning algorithm known as Deep Residual Learning for Image Recognition (ResNet) was developed to discriminate glaucoma, and its diagnostic accuracy was validated in the testing dataset, using the area under the receiver operating characteristic curve (AROC). The Deep Residual Learning for Image Recognition was constructed using the training dataset and validated using the testing dataset. The presence of glaucoma in the testing dataset was also confirmed by three Residents in Ophthalmology. The deep learning algorithm achieved significantly higher diagnostic performance compared to Residents in Ophthalmology; with ResNet, the AROC from all testing data was 96.5 (95% confidence interval [CI]: 93.5 to 99.6)% while the AROCs obtained by the three Residents were between 72.6% and 91.2%.

Patterns of posterior ocular complications in myopic eyes of Indian population

This is a retrospective study aimed to investigate the patterns of myopic fundus complications in Indian children and young adults. Electronic medical records of 29,592 patients, aged 10–40 years, who visited L V Prasad Eye Institute between 1^st January to 31^st December 2016 were analysed in the study. Data such as age, gender, refractive error and various pathologic lesions of posterior globe were considered for analysis. Among all the patients with different types of refractive errors, myopia was found in 47.4%, high myopia in 6.8% and pathologic myopia in 2.2%. There was no trend of the increased prevalence of pathologic myopia with increasing age, except for a significant difference between the children aged 10–15 years (2.7%) and those aged more than 15 years (>4%). . Although, the overall pattern of pathologic lesions was similar across different grades of myopia (2.5% in low myopes vs. 2.2% in severe myopes), lesions like staphyloma and retinal detachment increased with increasing degree of myopia. The proportion of pathologic lesions across different grades of myopia suggests the necessity for careful peripheral fundus examinations irrespective of the degree of myopia for better management and prognostic purposes.

Optic Disc Margin Anatomic Features in Myopic Eyes with Glaucoma with Spectral-Domain OCT

PURPOSE

To investigate optic disc margin anatomic features in myopic eyes with open-angle glaucoma (OAG) using spectral-domain (SD) OCT.

DESIGN

Cross-sectional study.

PARTICIPANTS

Two hundred four eyes of 102 participants with OAG and 106 eyes of 53 participants without glaucoma with axial length of 24 mm or more.

METHODS

Radial SD OCT B-scans centered on the optic discs were acquired in each eye, and the SD OCT data were colocalized with the optic disc stereophotographs. Optic disc margin anatomic features were evaluated as (1) SD OCT structure coinciding with the disc margin identified in the stereophotograph, (2) border tissue configuration, and (3) presence of Bruch's membrane overhang, and their frequency was computed in each clock-hour position. Further, paired eyes of myopic participants with OAG were divided into eyes with better or worse visual field defect (VFD), according to the mean deviation of the Humphrey visual field test, and associated factors were compared.

MAIN OUTCOME MEASURES

Spectral-domain OCT structures coinciding with the visible optic disc margin in stereophotographs.

RESULTS

In myopic eyes with OAG, mean axial length was 25.96±1.07 mm and mean deviation was -8.87±7.78 dB. In approximately 90% of the participants, anterior scleral opening (ASO) coincided with the temporal disc margin and Bruch's membrane opening (BMO) with the nasal disc margin. Border tissue configuration was externally oblique in the temporal region and internally oblique in the nasal region of the optic disc. Bruch's membrane overhang was observed in a relatively small percentage of eyes. The same pattern of disc margin anatomic features was observed in the myopic eyes without glaucoma. The myopic optic disc was shaped by the temporal shifting of the BMO from the ASO, and the extent of shifting was expressed as the width of γ zone parapapillary atrophy (PPA). The greater γ zone PPA width was associated significantly with the worse VFD between paired eyes.

CONCLUSIONS

The myopic eyes with OAG exhibited characteristic optic disc margin anatomic features that was considered to be derived from myopic deformation of the eye. The greater γ zone PPA width may increase susceptibility to the glaucomatous stress.

Environmental Risk Factors Can Reduce Axial Length Elongation and Myopia Incidence in 6- to 9-Year-Old Children

PURPOSE

To identify risk factors for axial length (AL) elongation and incident school myopia.

DESIGN

Population-based prospective birth-cohort study.

PARTICIPANTS

Four thousand seven hundred thirty-four children examined at 6 and 9 years of age from the Generation R Study in Rotterdam, The Netherlands.

METHODS

Axial length and corneal radius (CR) were measured with an IOLMaster 500 and daily life activities and demographic characteristics were obtained by questionnaire. Three thousand three hundred sixty-two children (71%) were eligible for cycloplegic refractive error measurements. Linear regression models on AL elongation were used to create a risk score based on the regression coefficients resulting from environmental and ocular factors. The predictive value of the prediction score for myopia (≤-0.5 diopter) was estimated using receiver operating characteristic curves. To test if regression coefficients differed for baseline AL-to-CR ratio, interaction terms were calculated with baseline AL-to-CR ratio and environmental factors.

MAIN OUTCOME MEASURES

Axial length elongation and incident myopia.

RESULTS

From 6 to 9 years of age, average AL elongation was 0.21±0.009 mm/year and myopia developed in 223 of 2136 children (10.4%), leading to a myopia prevalence at 9 years of age of 12.0%. Seven parameters were associated independently (P < 0.05) with faster AL elongation: parental myopia, 1 or more books read per week, time spent reading, no participation in sports, non-European ethnicity, less time spent outdoors, and baseline AL-to-CR ratio. The discriminative accuracy for incident myopia based on these risk factors was 0.78. Axial length-to-CR ratio at baseline showed statistically significant interaction with number of books read per week (P < 0.01) and parental myopia (P < 0.01). Almost all predictors showed the highest association with AL elongation in the highest quartile of AL-to-CR ratio; incidental myopia in this group was 24% (124/513).

CONCLUSIONS

Determination of a risk score can help to identify school children at high risk of myopia. Our results suggest that behavioral changes can offer protection particularly in these children.

Improving the structure-function relationship in glaucomatous and normative eyes by incorporating photoreceptor layer thickness

The purpose of the study was to investigate whether the structure-function relationship in glaucomatous and normative eyes is improved by considering photoreceptor layer thickness. Humphrey 10-2 visual fields (VF) and optical coherence tomography were carried out in 615 eyes of 391 subjects, including 100 eyes of 53 healthy controls and 515 eyes of 338 glaucoma patients. The relationship between mean VF sensitivity and the thickness of the retinal nerve fiber layer (RNFL) and ganglion cell layer and inner plexiform layer (GCL + IPL) was analyzed using linear mixed models, by glaucoma status and degree of myopia. The structure-function relationship was also analyzed by supplementing the RNFL and GCL + IPL thickness with the thicknesses of: (i) the inner nuclear layer and outer plexiform layer (INL + OPL); (ii) the outer nuclear layer and inner segment of photoreceptor layer (ONL + ISL); (iii) the outer segment layer of photoreceptor and retinal pigment epithelium (OSL + RPE). The model included total thickness of RNFL, GCL + IPL and OSL + RPE was highly more optimal than the model that only included the total thickness of RNFL and GCL + IPL, in all subsets of eyes by glaucoma status and degree of myopia.

Position of Central Retinal Vascular Trunk and Preferential Location of Glaucomatous Damage in Myopic Normal-Tension Glaucoma

PURPOSE

To investigate the spatial correlation between the central retinal vascular trunk and the preferential location of glaucomatous damage in myopic normal-tension glaucoma (NTG) eyes.

DESIGN

Cross-sectional study.

PARTICIPANTS

One hundred thirty-seven subjects with myopic NTG (137 eyes).

METHODS

The position of the vascular trunk was measured from the center of the Bruch membrane opening (BMO), which was delineated by optical coherence tomography imaging. The angular deviation was measured, with the horizontal nasal midline as 0° and the superior location as a positive value. The shift index was calculated as the distance of the vascular trunk from the BMO center relative to that of the BMO margin. The angular location of the midpoint of the retinal nerve fiber layer (RNFL) defect was measured from the BMO center. In cases with bi-hemispheric RNFL defects, the angular location was measured for the RNFL defect of larger width. For categorical analysis, hemispheric dominancy was determined if the RNFL defect in one hemisphere was larger than twofold that in the opposite hemisphere. In cases with no dominant hemisphere, the eye was classified as bi-equivalent involvement.

MAIN OUTCOME MEASURES

The vascular trunk position within the BMO and the location of glaucomatous damage.

RESULTS

The moderate- and severe-shift groups (shift index ≥ 0.5) were associated with younger age, longer axial length, smaller angular deviation, and lesser incidence of focal lamina cribrosa (LC) defect. A multiple regression analysis showed a significant correlation between the vascular trunk position and the RNFL defect location (P < 0.001). A logistic regression analysis revealed that the dominant RNFL defect occurred in the opposite hemisphere of the vascular trunk (P < 0.001), and bi-equivalent involvement in both hemispheres was associated with a larger shift index (P = 0.001). A conditional inference tree analysis showed that both the angular deviation (P < 0.001) and the extent of vascular trunk shift (P < 0.001) determined the RNFL defect location.

CONCLUSIONS

In myopic NTG eyes, the vascular trunk is located in the direction opposite of the RNFL defect with reference to the BMO. Because the vascular trunk is embedded in the LC, this implies that LC shift during axial elongation is associated with greater vulnerability of myopic eyes to glaucomatous damage.

The Prevalence and Associations of Peripheral Retinopathy: Baseline Study of Guangzhou Office Computer Workers

Purpose

To determine the prevalence of peripheral retinopathy and its associated risk factors among a sample of Guangzhou office computer workers.

Methods

A cross-sectional study of Guangzhou Chinese computer workstations and operators in different departments and units of the Guangzhou Power Supply Bureau, China, in 2016. Peripheral retinopathy was recorded and analyzed using a scanning laser ophthalmoscope (SLO; Optos, Daytona, United Kingdom) and slit-lamp microscopy combined with a three-mirror contact lens.

Results

The 1934 eyes of 967 subjects (513 females and 454 males) were included in this study. In total, 79.1% of the eyes were myopic in workers aged 20–29 years, 72.9% in workers aged 30–39 years, 62.2% in workers aged 40–49 years, and 43.4% in workers aged 50–59 years (p < 0.001). Most eyes had optic nerve crescents (81.3%). Various peripheral degenerations were found: 7 eyes (0.4%) had microcystoid degeneration, 40 (2.1%) had peripheral pigmentary degeneration, 87 (4.5%) had lattice degeneration, and 4 (0.2%) had snail-track degeneration. Nineteen (1.0%) eyes had paving-stone degeneration, 11 (0.6%) eyes had a retinal hole or tear, and 16 (0.8%) eyes had chorioretinal degeneration. Multivariate regression confirmed that greater axial length (OR: 1.18 (1.03, 1.35), p=0.012) and more serious spherical equivalent (OR: 0.82 (0.77, 0.88), p < 0.001) were significant risk factors for peripheral retinal changes.

Conclusion

Peripheral retinal degenerative changes were found in a larger proportion of younger computer workers than older ones. Myopia is occurring in younger and younger people, accompanied by peripheral retinal degeneration.

Correlations between the optic nerve head morphology and ocular biometrics in highly myopic eyes

AIM

To analyze peripapillary atrophy β/γ zone (PPA-β/γ) and the optic disc ovality index, and to assess their associations with the axial length (AL), refractive error, best corrected visual acuity (BCVA), choroidal thickness (CT), and age in highly myopic eyes.

METHODS

This was a retrospective observational case series. The study included 667 patients consecutively examined for highly myopic eyes [spherical equivalent ≤-6.0 diopters (D) and AL≥26 mm] with or without myopic retinopathy. Each patient went through a comprehensive ophthalmological examination that included spectral domain optical coherence tomography (SD-OCT) of the macula, A-mode ultrasonography, and a cycloplegic refraction test. The ovality index and PPA-β/γ area were measured from optic disc photographs.

RESULTS

A significant association was seen between PPA-β/γ area and the ovality index (P=0.000, r=-0.232). The PPA-β/γ area increased significantly with a longer AL, older age, worse BCVA, higher refractive error, and thinner choroid (P<0.01). The oval disc was significantly correlated with a longer AL, older age, worse BCVA, higher refractive error, larger PPA-β/γ area, and thinner choroid (P<0.01).

CONCLUSION

The PPA-β/γ zone and ovality index in highly myopic eyes show distinct associations with the AL, refractive error, BCVA, age, and CT.

Finite Element Biomechanics of Optic Nerve Sheath Traction in Adduction

Historical emphasis on increased intraocular pressure (IOP) in the pathogenesis of glaucoma has been challenged by the recognition that many patients lack abnormally elevated IOP. We employed finite element analysis (FEA) to infer contribution to optic neuropathy from tractional deformation of the optic nerve head (ONH) and lamina cribrosa (LC) by extraocular muscle (EOM) counterforce exerted when optic nerve (ON) redundancy becomes exhausted in adduction. We characterized assumed isotropic Young's modulus of fresh adult bovine ON, ON sheath, and peripapillary and peripheral sclera by tensile elongation in arbitrary orientations of five specimens of each tissue to failure under physiological temperature and humidity. Physical dimensions of the FEA were scaled to human histological and magnetic resonance imaging (MRI) data and used to predict stress and strain during adduction 6 deg beyond ON straightening at multiple levels of IOP. Young's modulus of ON sheath of 44.6 ± 5.6 MPa (standard error of mean) greatly exceeded that of ON at 5.2 ± 0.4 MPa, peripapillary sclera at 5.5 ± 0.8 MPa, and peripheral sclera at 14.0 ± 2.3 MPa. FEA indicated that adduction induced maximum stress and strain in the temporal ONH. In the temporal LC, the maximum stress was 180 kPa, and the maximum strain was ninefold larger than produced by IOP elevation to 45 mm Hg. The simulation suggests that ON sheath traction by adduction concentrates far greater mechanical stress and strain in the ONH region than does elevated IOP, supporting the novel concept that glaucomatous optic neuropathy may result at least partly from external traction on the ON, rather than exclusively on pressure on the ON exerted from within the eye.

Association Between Optic Nerve Head Deformation and Retinal Microvasculature in High Myopia

PURPOSE

To evaluate the retinal microvasculature of peripapillary and macular regions in highly myopic eyes and investigate the association between the vascular parameters and optic nerve head (ONH) deformation.

DESIGN

Cross-sectional study.

METHODS

Seventy-one subjects with highly myopic eyes and 26 subjects with emmetropic eyes were included. Horizontal B-scan images of the ONH were obtained using optical coherence tomography (OCT) and horizontal tilt angles were measured. Integrated automated algorithms in the Avanti OCT angiography were used to quantify the peripapillary vessel density and area of the foveal avascular zone (FAZ) at the level of superficial and deep vascular networks. Association between horizontal disc tilt and the vascular parameters was evaluated.

RESULTS

The mean axial length and horizontal tilt angle were 26.73 ± 0.63 mm and 9.77 ± 3.00 degrees in the highly myopic group and 23.46 ± 0.55 mm and 5.95 ± 3.48 degrees in the emmetropic group, respectively. Highly myopic eyes exhibited significantly lower average peripapillary vessel density (P = .010) and larger superficial and deep FAZs (P = .001 and P < .001, respectively) compared with emmetropic eyes. Linear regression analyses showed that horizontal tilt angle significantly correlated the average peripapillary vessel density (P = .037) and the areas of superficial (P < .001) and deep (P < .001) FAZs.

CONCLUSIONS

The retinal microvasculature was significantly different in highly myopic eyes according to the degree of horizontal optic disc tilt. In addition to peripapillary vessel density, FAZ can be affected by the degree of optic disc tilt.

Ten-Year Progression of Myopic Maculopathy: The Beijing Eye Study 2001-2011

PURPOSE

To investigate the progression pattern of myopic maculopathy and associated factors in a population-based study.

DESIGN

Population-based longitudinal study.

PARTICIPANTS

The Beijing Eye Study including 4439 participants in 2001 was repeated in 2011, with 2695 individuals (66.4%) being re-examined in 2011.

METHODS

The study participants underwent detailed ophthalmic and general examinations. Using fundus photographs obtained in 2001 and 2011, we assessed the progression of myopic maculopathy in highly myopic eyes with a refractive error ≥-6 diopters in 2001. Myopic maculopathy was differentiated into tessellated fundus (category 1), diffuse chorioretinal atrophy (category 2), patchy chorioretinal atrophy (category 3), and macular atrophy (category 4), with lacquer cracks and choroidal neovascularization as additional plus signs.

MAIN OUTCOME MEASURES

Progression pattern of myopic maculopathy.

RESULTS

Of 110 highly myopic eyes (70 individuals) at baseline, 39 eyes (35.5%) showed progression observed in 15 of 79 eyes (19%) with tessellated fundus at baseline, in 17 of 24 eyes (71%) with diffuse chorioretinal atrophy, in all 6 eyes with patchy chorioretinal atrophy, and the 1 eye with macular atrophy. Lacquer cracks detected in 2 eyes in 2001 developed into a small patchy atrophy (1 eye) or widened during the follow-up (1 eye). Five eyes demonstrated new lacquer cracks. In binary regression analysis, progression of myopic maculopathy was associated with longer axial length (P < 0.001; odds ratio [OR], 7.13; 95% confidence interval [CI], 2.49-20.4), older age (P = 0.001; OR, 1.25; 95% CI, 1.10-1.42), higher prevalence of staphylomas (P = 0.03; OR, 24.3; 95% CI, 2.89-204), smaller parapapillary γ-zone in 2011 (P = 0.01; OR, 0.61; 95% CI, 0.41-0.91), and female gender (P = 0.04; OR, 9.78; 95% CI, 1.06-90.6).

CONCLUSIONS

The 10-year progression rate of myopic maculopathy in this elderly Chinese population was 35.5%, increasing from 15 of 79 eyes (19%) in category 1 of myopic maculopathy at baseline to 17 of 24 eyes (71%) in category 2 and 6 of 6 eyes (100%) in category 3. Risk factors for myopic maculopathy progression were longer axial length, pre-existing staphylomata, smaller parapapillary γ-zone, older age, and female gender.

Prevalence of posterior staphyloma and factors associated with its shape in the Japanese population

Myopia is increasing rapidly worldwide. We performed a cross-sectional study to investigate the prevalence of posterior staphyloma, a complication of myopia, and its shape characteristics in relation to age, sex, and axial length (AL) in a Japanese community-based cohort. The right eyes of 3748 participants who underwent fundus photography and optical coherence tomography (OCT) examination were evaluated. Posterior staphyloma prevalence was evaluated using fundus photographs and OCT images. Furthermore, fundus shapes were analyzed by measuring local fundus curvatures on 6 mm cross-line OCT images at intervals of 1 µm. The mean and variance of the curvatures were calculated to represent the fundus shape of each eye for investigation of the relationship between fundus curvature and age, sex, and AL. Seventy-seven eyes (2.05%) had posterior staphyloma. The mean and variance of the fundus curvatures were significantly greater in women than in men and became greater with age, suggesting that the shape of the staphyloma was steeper and less smooth in women and elderly subjects. AL and mean curvature showed a significant correlation (P = 2 × 10⁻¹⁶, R = 0.480), which was significantly affected by age (P < 2 × 10⁻¹⁶). Quantitative analysis of fundus shapes was useful for statistical analysis of posterior staphyloma in relation to age, sex, and AL.

Positional Change of Optic Nerve Head Vasculature during Axial Elongation as Evidence of Lamina Cribrosa Shifting: Boramae Myopia Cohort Study Report 2

PURPOSE

To investigate the positional change of central retinal vasculature and vascular trunk to deduce the change in the lamina cribrosa (LC) during axial elongation.

DESIGN

Prospective cohort study.

PARTICIPANTS

Twenty-three healthy myopic children (46 eyes).

METHODS

Participants had undergone a full ophthalmologic examination and axial length measurement every 6 months for 2 years. Using spectral-domain OCT, circle scans centered around the optic disc in the glaucoma progression analysis mode, which enabled capturing of the same positions throughout the entire study period, and enhanced depth imaging of the deep optic nerve head complex were performed. Infrared imaging of the circle scans was used to measure the changes in the angles between the first and final visits. The angle between the major superior and inferior retinal arteries was measured along the circle scan twice: from the center of the circle scan and from the central retinal vascular trunk, respectively. The positional change of the retinal vascular trunk also was measured.

MAIN OUTCOME MEASURES

Change in vascular angle and position of vascular trunk with axial elongation and associated factors.

RESULTS

The vascular angle measured from the center of the circle scan did not change (P = 0.247), whereas the angle measured from the central retinal arterial trunk decreased with axial elongation (P < 0.001). A generalized estimating equation analysis revealed that the factors associated with angle decrease were axial elongation (P = 0.004) and vascular trunk dragging (P < 0.001). The extent of vascular trunk dragging was associated with axial elongation (P < 0.001) and increased border length with marginal significance (P = 0.053), but the extent of dragging could not be explained fully by their combination. The major directionality of dragging was mostly to the nasal side of the optic disc, with large variations among participants.

CONCLUSIONS

During axial elongation, the retinal vasculature at the posterior pole was unchanged, whereas the position of the central vascular trunk was dragged nasally. Because the central retinal vascular trunk is embedded in the LC, its dragging indicates nasal shifting of the LC, which could explain the vulnerability of myopic eyes to glaucomatous optic neuropathy.

Retinal Nerve Fiber Layer Protrusion Associated with Tilted Optic Discs

SIGNIFICANCE

This study resulted in the identification of an optic nerve head (ONH) feature associated with tilted optic discs, which might potentially contribute to ONH pathologies. Knowledge of such findings will enhance clinical insights and drive future opportunities to understand disease processes related to tilted optic discs.

PURPOSE

The aim of this study was to identify novel retinal nerve fiber layer (RNFL) anomalies by evaluating tilted optic discs using optical coherence tomography. An observed retinal nerve fiber protrusion was further investigated for association with other morphological or functional parameters.

METHODS

A retrospective review of 400 randomly selected adult patients with ONH examinations was conducted in a referral-only, diagnostic imaging center. After excluding other ONH pathologies, 215 patients were enrolled and evaluated for optic disc tilt and/or torsion. Gross anatomical ONH features, including size and rim or parapapillary region elevation, were assessed with stereoscopic fundus photography. Optical coherence tomography provided detailed morphological information of individual retinal layers. Statistical analysis was applied to identify significant changes between individual patient cohorts.

RESULTS

A dome-shaped hyperreflective RNFL bulge, protruding into the neurosensory retina at the optic disc margins, was identified in 17 eyes with tilted optic discs. Available follow-up data were inconclusive regarding natural changes with this ONH feature. This RNFL herniation was significantly correlated with smaller than average optic disc size (P = .005), congenital disc tilt (P < .0001), and areas of rim or parapapillary elevation (P < .0001).

CONCLUSIONS

This study reports an RNFL protrusion associated with tilted optic discs, which has not previously been assessed as an independent ONH structure. The feature is predominantly related to congenital crowded, small optic discs and variable between patients. This study is an important first step to elucidate diagnostic capabilities of tilted disc morphological changes and understanding associated functional deficits.

Three Dimensional Evaluation of Posterior Pole and Optic Nerve Head in Tilted Disc

For over a century, tilted disc syndrome (TDS) has been defined vaguely. The lack of consensus of the terminology arises from the lack of understanding of the pathogenesis of this condition. Also, myopic discs with temporal crescents or peripapillary atrophy (PPA) are histologically indistinguishable from TDS. Therefore, we examined the morphological background of the extreme ONH appearances such as the myopic tilted disc and the TDS by analyzing the posterior segment of the eye from a three-dimensional (3D) perspective. 107 eyes of 107 subjects were classified into 3 groups with respect to the optic disc torsion degrees: (1) mild torsion (0–30 degrees; 35 eyes) and (2) moderate torsion (30–60 degrees; 35 eyes) and (3) severe torsion (60–90 degrees; 37 eyes). SSOCT images were analyzed in coronal view, which supplements anterior-posterior depth (z axis in Cartesian coordinates). The amount of optic disc torsion was significantly correlated with Disc-DPE angle and Fovea-Disc depth (r = 0.548, P < 0.001 and r = 0.544, P < 0.001). In conclusion, we describe specific types of posterior sclera configuration that corresponds to the increasing degree of optic disc torsion, even in the extreme ONH appearances such as the myopic tilted disc and the TDS. These findings suggest that the optic disc appearance is determined by the configuration of the posterior sclera.

Ocular and Clinical Characteristics Associated with the Extent of Posterior Lamina Cribrosa Curve in Normal Tension Glaucoma

Although normal-tension glaucoma (NTG) is pathogenetically heterogenous, there have been few attempts to subclassify NTG patients according to the mechanism and anatomy of optic nerve damage. This cross-sectional study was performed to investigate differences in the clinical and ocular characteristics between NTG patient groups stratified according to the degree of posterior lamina cribrosa (LC) curve which was assessed by calculating LC curvature index (LCCI). A total of 101 eyes of 101 treatment naïve NTG patients were included. The optic nerve head was imaged using enhanced-depth-imaging spectral-domain optical coherence tomography in three horizontal B-scan images in each eye. The patients were divided into two groups based on the magnitude of LCCI using a cutoff of known upper 95 percentile value in healthy subjects: a steeply curved LC group (Group 1, 75 eyes, 74.3%) and a relatively flat LC group (Group 2, 26 eyes, 25.7%). NTG eyes with relatively flat LC had lower intraocular pressure, and were associated with greater parapapillary structural alternation and systemic risk factors. These data suggest that assessment of LC morphology may help clinicians seek additional risk factors and make inferences about the mechanism of optic nerve damage in individual patients.

Lamina Cribrosa Morphology Predicts Progressive Retinal Nerve Fiber Layer Loss In Eyes with Suspected Glaucoma

Although early diagnosis and treatment reduce the risk of blindness from glaucoma, the decision on whether or not to begin treatment in patients with suspected glaucoma is often a dilemma because the majority of patients never develop definite glaucoma. A growing body of evidences suggests that posterior bowing of the lamina cribrosa (LC) is the earliest structural change preceding the retinal nerve fiber layer (RNFL) loss in glaucomatous optic neuropathy. Based on this notion, we conducted a prospective study enrolling 87 eyes suspected of having glaucoma to investigate whether the future rate of RNFL loss is associated with the baseline LC curve evaluated by measuring the LC curve index (LCCI) using enhanced depth imaging optical coherence tomography. A faster rate of RNFL loss was significantly associated with greater LCCI (P < 0.001;standardized coefficient beta = −0.392), older age (P = 0.008;beta = −0.314), and greater vertical cup-to-disc ratio (P = 0.040;beta = −0.233). Assessment of LC morphology may help predict the disease outcome in eyes with suspected glaucoma.

Knobby Eye Syndrome

INTRODUCTION

A spherical globe is traditionally assumed, but this study employed magnetic resonance imaging (MRI) to demonstrate frequent occurrence of non-spherical staphylomata in strabismic patients.

METHODS

High-resolution, surface coil MRI was obtained in multiple image planes in 21 highly myopic subjects (36 eyes) and compared with 17 normal controls (33 eyes). Images were analyzed for axial length, aspect ratio of eye shape, and deflection of muscle paths.

RESULTS

All but two high myopes had strabismus. While myopic globes were generally spherical in 10 myopic eyes including both orthotropic subjects, 15 globes exhibited diffuse posterior staphylomata, 16 equatorial staphylomata, and 4 both posterior and equatorial staphylomata. Equatorial scleral ectasias were positioned to contact and elongate paths of horizontal rectus muscles in some gaze positions. Axial length in myopes averaged 28.8 ± 3.8 (SD) mm and did not differ significantly between regular vs. irregular staphylomata. Globe aspect ratios in the coronal, axial, and sagittal planes were significantly greater than normal in myopes (P < 0.005), but correlated significantly with axial length only in the axial and sagittal planes (P < 0.03). While myopes with irregular staphylomata were older at 57 ± 11 years than subjects with spherical globes at 24 ± 8 years (P < 0.0005), other clinical features were similar.

CONCLUSION

Irregular equatorial or posterior staphylomata are common in strabismic axial high myopes, acting, like "cams" affixed to the normally spherical globe so that they may have no mechanical effect until rotating eccentrically against muscles. After rotational contact, staphylomata would nonlinearly increase muscle tension with further duction. Imaging may be clinically informative about this "knobby eye syndrome."

Three-Dimensional Evaluation of Posterior Pole and Optic Nerve Head in Myopes with Glaucoma

The degree of myopia is represented by a global index, such as refractive error or axial length. However, the progression of myopia mainly develops in the posterior eyeball. Therefore, it is reasonable to assume that the evaluation of myopia should be confined to the posterior segment, where most of the growth and lengthening occurs. Swept source optical coherence tomography software can reconstruct the scans to the coronal view of the posterior pole, which provides additional anterior-posterior depth (z axis in the Cartesian coordinates) that is not provided with the common fundus photograph. We deduced that the parameter of deepest point of the eyeball (DPE) as a surrogate for posterior pole configuration. Between myopes with and without normal tension glaucoma (NTG) with similar axial length, myopes with NTG had deeper and more distant location of the DPE from the optic disc. The difference of the DPE position between the myopes with and without NTG may have implications for the larger optic disc tilt and torsion characteristic of myopes with NTG. Furthermore, these data suggest that myopes with NTG go through excessive posterior scleral remodeling, which may result in vulnerable optic nerve head.

Progressive Deformation of the Optic Nerve Head and Peripapillary Structures by Graded Horizontal Duction

Purpose

We investigated the effect of graded range of horizontal duction on the shape of the peripapillary Bruch's membrane (ppBM) and optic nerve head (ONH).

Methods

In 50 eyes of 25 normal subjects, the ONH and peripapillary retina were imaged by optical coherence tomography (OCT) in central gaze and incremental angles of add- and abduction. Displacements of the Bruch's membrane opening (BMO), optic cup (OC), and change in ONH angle in eccentric gazes were compared to those of central gaze, in add- and abduction.

Results

With increasing duction, the nasal edge of the BMO (nBMO) shifted progressively anteriorly in adduction and posteriorly in abduction, while the temporal edge of the BMO (tBMO) shifted posteriorly in adduction and anteriorly in abduction. The summed absolute nBMO and tBMO displacements in 30° and 35° adduction significantly exceeded those in comparable abduction angles (P < 0.005 for both). The ONH progressively tilted temporally in adduction and nasally in abduction; absolute ONH tilt in adduction was significantly greater than that in abduction for 30° and 35° ductions (P < 0.005 for both). BMO displacement and ONH tilt in adduction exhibited bilinear behavior, with greater effects for both at angles exceeding 26°. The OC shifted significantly farther anteriorly in abduction than adduction at every angle from 10° to 35°.

Conclusions

Horizontal duction deforms the ONH and ppBM, but more in adduction than in abduction, and increasingly so for angles greater than 26°. This behavior is consistent with optic nerve sheath tethering for adduction exceeding 26°.

Retinal Nerve Fiber Layer Damage in Young Myopic Eyes With Optic Disc Torsion and Glaucomatous Hemifield Defect

PURPOSE

To investigate retinal nerve fiber layer (RNFL) status at the opposite hemiretinas of optic disc torsion (ODT) in young myopic subjects with glaucomatous visual field (VF) defects and correlation between its thickness and VF defects using spectral-domain optical coherence tomography (SD-OCT).

PATIENTS AND METHODS

We assessed the frequency and characteristics of glaucomatous RNFL defects at the opposite hemiretinas of ODT location (ODT-unaffected hemiretinas) in 59 young myopic subjects presenting with glaucomatous VF defects confined to 1 hemifield, and compared the peripapillary RNFL thickness (pRNFLT) in ODT-unaffected hemiretinas of study eyes with that of 60 myopic controls without ODT using Cirrus HD SD-OCT. Linear regression analyses were performed between the pRNFLT measurements at ODT-unaffected hemiretinas and Humphrey field analyzer VF indices.

RESULTS

Approximately 42% of study eyes with ODT showed glaucomatous RNFL defects at ODT-unaffected hemiretinas. The mean width of RNFL defects was significantly greater in ODT-affected hemiretinas than in ODT-unaffected hemiretinas (P<0.001). The mean pRNFLT in ODT-unaffected hemiretinas of study group (99.9±12.1 μm) was significantly lower than that in the matched hemiretinas of control group (109.8±14.9 μm; P<0.001). Significant correlations were observed between pRNFLT parameters and Humphrey field analyzer indices for each hemiretina with or without ODT in the study group.

CONCLUSIONS

Young myopic eyes with ODT and hemifield VF loss often show glaucomatous RNFL defects at both hemiretinas and significantly lower pRNFLT in the ODT-unaffected hemiretinas compared with matched hemiretinas of control eyes. Greater VF loss is associated with more advanced pRNFT loss in ODT-unaffected hemiretinas.

Optic Disc Characteristics and Visual Field Progression in Normal Tension Glaucoma Patients With Tilted Optic Discs

PURPOSE OF THE STUDY

The purpose of the study was to evaluate the optic disc characteristics associated with visual field (VF) progression in normal tension glaucoma (NTG) eyes with tilted optic discs.

METHODS

Sixty-six eyes of 66 NTG patients with tilted optic disc were included in this cross-sectional study, who were examined by at least 5 Humphrey 30-2 VFs. Glaucomatous VF progression was evaluated using pointwise linear regression. Optic nerve heads were scanned with enhanced-depth imaging optical coherence tomography (EDI-OCT), and evaluated for the focal lamina cribrosa (LC) defects and LC thicknesses. Optic disc torsion degrees and tilt ratios were measured from disc photographs. Logistic regression analyses were used to identify the risk factors for VF progression and focal LC defects.

RESULTS

Multivariate analysis showed that VF progression was associated with the presence of focal LC defects and greater number of VFs. The eyes with focal LC defects were associated with greater torsion degree and tilt ratio in multivariate analysis. The VF mean deviation slopes and localized VF progression rates in eyes with focal LC defects were greater than those without defects.

CONCLUSIONS

The greater optic disc tilt and torsion in NTG eyes with tilted optic disc were associated with focal LC defects, but not with VF progression. The focal LC defects were associated with VF progression. This study suggests that the focal LC defects in NTG patients with tilted optic disc may be an independent risk factor for glaucomatous VF progression, and the development of focal LC defects could be influenced by optic disc torsion or tilt.

FEATURES OF POSTERIOR STAPHYLOMAS ANALYZED IN WIDE-FIELD FUNDUS IMAGES IN PATIENTS WITH UNILATERAL AND BILATERAL PATHOLOGIC MYOPIA

PURPOSE

Pigmentary alterations along the presumed edge of staphyloma in wide-field fundus images have been reported to be highly correlated with the eye shape in three-dimensional magnetic resonance images. The purpose of this study was to analyze Optos images in a large series of highly myopic patients to determine the prevalence, types, and features of staphylomas.

METHODS

One thousand and sixty eyes of 541 patients with high myopia (axial length ≥ 26.5 mm) in at least one eye were retrospectively analyzed in Japan and Spain. To determine the presence and types of staphyloma, the authors focused on pigmentary abnormalities along the presumed edge of staphylomas with at least one positive finding in fundus images, autofluorescent images, and infrared images by Optos.

RESULTS

Posterior staphyloma was detected in 552 of 1,060 eyes (55%) in Optos images. Wide macular type was the most common (79%), followed by narrow macular (15%), then peripapillary (3%), inferior, and finally nasal. In the 60 non-highly myopic eyes of patients with unilateral high myopia, staphyloma was detected in 40%, suggesting that unilateral high myopia might be a bilateral disorder with marked differences in the degree of staphyloma between the two eyes. Combined staphylomas such as the peripapillary type within the wide macular type were also found.

CONCLUSION

Posterior staphyloma was found in 55% of 1,060 eyes with bilateral or unilateral pathologic myopia. Wide macular was the most common type, although there were much more variations in the shape of staphylomas than that had been previously believed.

Magnetic Resonance Imaging of Optic Nerve Traction During Adduction in Primary Open-Angle Glaucoma With Normal Intraocular Pressure

Purpose

We used magnetic resonance imaging (MRI) to ascertain effects of optic nerve (ON) traction in adduction, a phenomenon proposed as neuropathic in primary open-angle glaucoma (POAG).

Methods

Seventeen patients with POAG and maximal IOP ≤ 20 mm Hg, and 31 controls underwent MRI in central gaze and 20° to 30° abduction and adduction. Optic nerve and sheath area centroids permitted computation of midorbital lengths versus minimum paths.

Results

Average mean deviation (±SEM) was −8.2 ± 1.2 dB in the 15 patients with POAG having interpretable perimetry. In central gaze, ON path length in POAG was significantly more redundant (104.5 ± 0.4% of geometric minimum) than in controls (102.9 ± 0.4%, P = 2.96 × 10⁻⁴). In both groups the ON became significantly straighter in adduction (28.6 ± 0.8° in POAG, 26.8 ± 1.1° in controls) than central gaze and abduction. In adduction, the ON in POAG straightened to 102.0% ± 0.2% of minimum path length versus 104.5% ± 0.4% in central gaze (P = 5.7 × 10⁻⁷), compared with controls who straightened to 101.6% ± 0.1% from 102.9% ± 0.3% in central gaze (P = 8.7 × 10⁻⁶); and globes retracted 0.73 ± 0.09 mm in POAG, but only 0.07 ± 0.08 mm in controls (P = 8.8 × 10⁻⁷). Both effects were confirmed in age-matched controls, and remained significant after correction for significant effects of age and axial globe length (P = 0.005).

Conclusions

Although tethering and elongation of ON and sheath are normal in adduction, adduction is associated with abnormally great globe retraction in POAG without elevated IOP. Traction in adduction may cause mechanical overloading of the ON head and peripapillary sclera, thus contributing to or resulting from the optic neuropathy of glaucoma independent of IOP.

Optical Coherence Tomography and Biometry in High Myopia with Tilted Disc

PURPOSE

The purpose of this study was to compare retinal thickness and biometric parameters between highly myopic eyes with and without tilted optic discs.

METHODS

A total of 60 eyes from 60 highly myopic individuals (defined as a mean spherical equivalent refraction of -6.00 D or greater and axial length ≥26 mm) underwent detailed ophthalmic examination. Twenty-one eyes (13 females and 8 males; mean age: 29 ± 7 years) with tilted optic discs were recruited and compared with 39 eyes (23 females and 16 males; mean age: 28 ± 6 years) of control subjects without tilted optic discs using spectral domain optical coherence tomography (OCT) and the Lenstar biometer. Disc ovality was assessed using the ratio of minimum to maximum disc diameter (index of tilt). A ratio of ≤0.80 was considered as a tilted optic disc.

RESULTS

There were no significant differences in biometric parameters between two groups. However, myopia in the tilted disc group was significantly greater compared to the non-tilted group (-8.82 ± 1.58 D vs. -7.84 ± 1.22 D, p = 0.01). Comparison of OCT sectoral macular nerve fiber layer measurements between groups showed significant differences in inner ring thicknesses for the nasal (p = 0.01), inferior (p < 0.001), and temporal (p = 0.04) quadrants. A significant difference was also seen in outer ring macular nerve fiber layer thickness for the temporal quadrant (p = 0.03). No significant differences were demonstrated in optic disc peripapillary retinal nerve fiber layer (RNFL) thickness between the two groups.

CONCLUSIONS

Mean spherical equivalent refractive error is strongly correlated with optic disc tilt; however, other biometric factors are independent of tilt. Structural examination of the eye using OCT can be employed to differentiate between eyes with tilted optic discs and those with normal discs. Peripapillary RNFL appears to be unaffected by tilted discs.

The Location of the Deepest Point of the Eyeball Determines the Optic Disc Configuration

Tilted and rotated appearances are hallmarks of the myopic optic disc. As the eyeball grows axially, the posterior pole elongates not only globally but in a localized manner as well. In this process, the optic disc is pulled towards the deepest point of the elongated eyeball, which might result in a change in optic disc configuration. Thus, we hypothesized that analyzing the variation of posterior pole contour can play a major role in understanding optic disc configuration in myopic subjects. By analyzing consecutive images of swept source OCT coronal sections at the posterior pole, the deepest interface between Bruch's membrane and the choroid could be identified as the deepest point of the eyeball (DPE). The location and the properties of the DPE differed significantly between the 125 eyes of non-glaucomatous myopic group and the 40 eyes of non-glaucomatous emmetropic group classified based on 24 mm axial length. The results suggested that the larger disc to DPE angle and the larger disc to DPE depth strongly predicts the optic disc torsion degree and the optic disc tilt. Our findings suggest that identifying the posterior pole profile plays a major role in understanding the optic disc alterations found in myopic subjects.

Associations between Optic Nerve Head-Related Anatomical Parameters and Refractive Error over the Full Range of Glaucoma Severity

Purpose

To evaluate the associations between optic disc (OD)-related anatomical parameters (interartery angle [IAA] between superior and inferior temporal retinal arteries, OD tilt [TL], rotation [ROT], and torsion [TO], OD surface curvature [CUR], and central retinal vessel trunk entry point location [CRVTL] on OD) and the spherical equivalent of refractive error (SE), and to assess the impact of glaucoma severity on these relationships.

Methods

Cirrus optical coherence tomography (OCT) fundus images and 24-2 visual fields of 438 patients were included. Ellipses were fitted to OD borders. IAA was calculated between marked retinal artery locations on a circle around OD. Blood vessel entry point on OD was marked to locate CRVTL. TL was measured as the angle between the lines fitted to OD clinical boundary and the Bruch's membrane edges on the horizontal B-scans. Ellipse rotation relative to the vertical axis defined ROT. Angle between the long axis of OD and the interartery line defined TO. CUR was determined by the inner limiting membrane on the horizontal B-scans. Linear regression models evaluated by Bayes Factors (BF) were used to determine the covariance structure between the parameters and SE as well as possible impacts of mean deviation (MD).

Results

Our results showed that CRVTL had the strongest relationship with SE, followed by ROT, TL, and IAA (BFs: 3.59 × 10⁷, 2645, 1126, and 248, respectively). MD did not significantly modulate the relationship between ONH parameters and SE.

Conclusion

Our results suggest that SE should be considered when interpreting the OD and its circumpapillary region for diagnostic purposes.

Translational Relevance

The reported relationships between OD-related parameters and ametropia may help to decrease false-positive clinical diagnoses of optic neuropathies.

Optic Nerve Tilt, Crescent, Ovality, and Torsion in a Multi-Ethnic Cohort of Young Adults With and Without Myopia

Purpose

The purpose of this article is to evaluate optic nerve head (ONH) characteristics in an ethnically diverse cohort of young U.S. adults.

Methods

In this study, 409 myopes and 206 nonmyopes (median age 22 years) completed measures including biometry and spectral domain optical coherence tomography from enface (ovality and torsion) and cross-sectional (tilt and crescent width) scans. Associated factors were evaluated using multivariable models.

Results

In myopic versus nonmyopic right eyes, median tilt (6.0° vs. 2.4°; P < 0.0001) and frequency of crescents (49% vs. 10%; P < 0.0001) were higher in myopes. Right eyes with crescents had higher median tilts (8.8° [myopic], 9.0° [nonmyopic]) than those without crescent (2.5° [myopic], 2.1° [nonmyopic]), irrespective of refractive group (both P < 0.0001). Torsion was similar between groups, with a slight difference in ovality (0.89 vs. 0.91; P < 0.03). Data in the left eyes were similar, and modeling was done only for the right myopic eyes. Multivariable models showed that an increased tilt was associated with ethnicity (P < 0.001), the presence of crescent (P < 0.001), and smaller ONH diameter (P < 0.0031), with interactions between ethnicity and crescent (P = 0.002). Specifically, ONH tilt was significantly higher in Asian eyes without crescent (P < 0.0001 for all comparisons), and crescent width was associated with increased tilt in non-Asian eyes (P < 0.02). Crescent width was associated with ethnicity (greatest in Asians) and disc tilt. Interactions were observed between tilt and ethnicity, whereby tilt had a greater effect on crescent width in non-Asian eyes, and crescent width was associated with increased tilt in non-Asian eyes.

Conclusions

The data clarify the influence of ethnicity and myopia on ONH characteristics in young adults and may inform future studies of biomechanical properties or of retinal pathology of the myopic eye.

Deformation of Optic Nerve Head and Peripapillary Tissues by Horizontal Duction

PURPOSE

To ascertain deformation of the optic nerve head (ONH) and peripapillary tissues caused by horizontal duction.

DESIGN

Prospective, experimental study.

METHODS

Optical coherence tomography of the ONH region was performed in 23 eyes of 12 normal volunteers in central gaze and increasing (10, 20, and 30 degrees) adduction and abduction. Main outcome measures were changes from central gaze in the configuration of the ONH and peripapillary tissues in eccentric gazes.

RESULTS

Adduction but not abduction was associated with significant, progressive relative posterior displacement of the temporal peripapillary retinal pigment epithelium (tRPE) from its position in central gaze reaching 49 ± 10 μm in 30-degree adduction (standard error of mean, P < .0001). Absolute (anterior or posterior) optic cup displacement (OCD) averaged 41 ± 7 μm in 30-degree adduction. Linear regression showed significant effect of adduction on absolute OCD (slope 1.09 ± 0.36 μm/degree, P = .0037). In 20-degree and 30-degree adduction, all eyes exhibited significant progressive temporal ONH tilting reaching 3.1 ± 0.4 degrees in 30-degree adduction (P < .0001). Abduction was not associated with significant peripapillary RPE displacement, OCD, or ONH tilt. Both nasal and temporal peripapillary choroid averaged 9-19 μm thinner in adduction and abduction than in central gaze (P < .02).

CONCLUSIONS

Adduction temporally tilts and displaces the prelaminar ONH and peripapillary tissues. Both adduction and abduction compress the peripapillary choroid. These effects support magnetic resonance imaging and biomechanical evidence that adduction imposes strain on the ONH and peripapillary tissues. Repetitive strain from eye movements over decades might in susceptible individuals lead to optic neuropathies such as normal tension glaucoma.

Epidemiology of Pathologic Myopia in Asia and Worldwide

The myopia epidemic in Asia is evident because the prevalence of high myopia among young adults is higher among Asian (6.8%-21.6%) compared with non-Asian populations (2.0%-2.3%). High myopia is linked to pathologic myopia (PM), which may cause irreversible visual impairment (VI). This review will highlight updates on the prevalence of PM and the associated VI from PM. The prevalence of PM among the middle-aged and elderly (0.9%-3.1%) is higher than the prevalence among children and adolescents (<0.2%). The PM lesions detected among older adults include advanced lesions, such as posterior staphyloma, chorioretinal atrophy, lacquer cracks, and Fuchs spot (in descending frequency of occurrence). A relatively high prevalence of PM (8%) was recently reported among highly myopic young adults. As young individuals grow older, the early grades of PM lesions are likely to progress to advanced grades. Two longitudinal changes that occur frequently in PM include the enlargement of beta peripapillary atrophy and the development of chorioretinal atrophy. The lack of longitudinal changes in PM limits the causal inferences of PM. The prevalence of VI attributed to PM seems to be higher among Asian populations compared with Western and European populations. Pathologic myopia is ranked as a more important cause of blindness and low vision in Asian populations compared with Western and European populations. With the lack of effective treatment strategies and poor prognosis, PM threatens the vision health of populations in Asia and worldwide. To control this future epidemic, the prevention of myopia onset and progression is necessary.

Visual field assessment in high myopia with and without tilted optic disc

BACKGROUND

The aim was to evaluate the effect of the tilted optic disc on the visual field in highly myopic eyes.

METHODS

A total of 58 eyes from 58 highly myopic individuals underwent detailed ophthalmic examination and were categorised into two groups according to the presence of a tilted optic disc. The visual field of 20 eyes (mean age of 28.95 ± 7.22 years) with tilted optic discs were compared with 38 eyes (mean age of 27.87 ± 6.08 years) of control subjects without tilted optic discs using the 30-2 SITA standard protocol with a Humphrey Field Analyzer - HFA II-i. Optic disc tilt was assessed from retinal photographs exported to Adobe Photoshop software. Disc ovality was assessed using the ratio of minimum to maximum disc diameter. A ratio of up to 0.80 was considered a tilted optic disc.

RESULTS

Foveal threshold sensitivity showed no statistically significant difference between tilted and non-tilted groups (35.16 ± 2.71 dB versus 35.37 ± 2.35 dB, p = 0.76). The mean deviation was -3.29 ± 2.03 dB in the tilted group and -3.49 ± 2.56 dB in the non-tilted group (p = 0.77). Additionally, there were no significant differences in the average deviation between the two groups in four quadrants and four hemifields; however, the lowest average deviation was observed in the superotemporal quadrant in the tilted group (-4.54 ± 3.16 dB). In the non-tilted group, 29 per cent had no visual field defect, 24 per cent had an arcuate scotoma and 20 per cent had generalised depression. In the tilted group, 30 per cent had an arcuate scotoma, 30 per cent had generalised depression and 13 per cent had no visual field defect. Other visual field defects occurred at frequencies less than 15 per cent in both groups.

CONCLUSIONS

The investigation of visual field patterns may be more appropriate than quantitative indices (for example, total mean deviation, foveal threshold sensitivity, average deviation) to assess the visual field in highly myopic patients with tilted optic discs.

Association of Myopic Deformation of Optic Disc with Visual Field Progression in Paired Eyes with Open-Angle Glaucoma

Purpose

The influence of myopia on glaucoma progression remains unknown, possibly because of the multifactorial nature of glaucoma and difficulty in assessing a solo contribution of myopia. The purpose of this study is to investigate the association of myopia with visual field (VF) progression in glaucoma using a paired-eye design to minimize the influence of confounding systemic factors that are diverse among individuals.

Methods

This retrospective study evaluated 144 eyes of 72 subjects with open-angle glaucoma, with similar intra-ocular pressure between paired eyes, spherical equivalent (SE) ≤ -2 diopter (D), and axial length ≥ 24 mm. Paired eyes with faster and slower VF progression were grouped separately, according to the global VF progression rate assessed by automated pointwise linear regression analysis. The SE, axial length, tilt ratio and torsion angle of optic discs, Bruch’s membrane (BM) opening area, and gamma zone parapapillary atrophy (PPA) width were compared between the two groups. Factors associated with faster VF progression were determined by logistic regression analysis.

Results

The mean follow-up duration was 8.9 ± 4.4 years. The mean value of SE and axial length were -6.31 ± 1.88 D and 26.05 ± 1.12 mm, respectively. The mean global visual field progression rate was -0.32 ± 0.38 dB/y. Tilt ratio, BM opening area, and gamma zone PPA width were significantly greater in the eyes with faster VF progression than those with slower progression. In multivariate analysis, these factors were significantly associated with faster VF progression (all P < 0.05), while SE and axial length were not associated with it.

Conclusion

In myopic glaucoma subjects, tilt of the optic disc and temporal shifting and enlargement of the BM opening were associated with faster rate of VF progression between paired eyes. This suggests that myopia influences VF progression in glaucomatous eyes via optic disc deformations rather than via refractive error itself.

Ocular characteristics associated with the location of focal lamina cribrosa defects in open-angle glaucoma patients

PurposeTo investigate the clinical characteristics according to the location of focal lamina cribrosa (LC) defects and its associated ocular features.Patients and methodsA total of 139 open-angle glaucoma patients underwent Spectralis optical coherence tomography (OCT) with enhanced depth imaging. Alterations in the contour of the LC were investigated to find focal LC defects. The location of the visible LC defect from the neural canal wall (far-peripheral and mid-peripheral) and clock-hour position (superotemporal, temporal and inferotemporal) were classified. Disc ovality ratio and disc-foveal angle were measured from disc and retinal nerve fiber layer (RNFL) photographs. The disc tilt degree was measured using a Heidelberg Retina Tomograph (HRT) III system. The en face OCT image of the disc scans was registered to the disc and RNFL photographs, to determine whether the focal LC defects corresponded spatially to the glaucomatous damage location.ResultsEyes with far-peripheral LC defects were significantly myopic and had a higher disc ovality ratio. The disc tilt degree obtained by HRT revealed significant temporal disc tilt in eyes with temporal LC defects (P<0.001). Eyes with inferotemporal LC defects had a significantly larger disc-foveal angle (P=0.027). The inferotemporal LC defects corresponded to the location of glaucomatous damage in 81.6%; however, only 46.2% of eyes with a superotemporal LC defect and 3.2% of eyes with a temporal LC defect corresponded spatially with the glaucomatous damage location.ConclusionsThe clinical characteristics and association with glaucomatous damage location were different according to the location of focal LC defect.

Ganglion Cell-Inner Plexiform Layer, Peripapillary Retinal Nerve Fiber Layer, and Macular Thickness in Eyes with Myopic β-Zone Parapapillary Atrophy

Purpose. To assess the correlations of myopic β-zone parapapillary atrophy (β-PPA) with the optic nerve head (ONH) and retina. Methods. We selected 27 myopic patients who showed prominent β-PPA in one eye and no β-PPA in the other eye. We studied their macula, macular ganglion cell-inner plexiform layer (mGCIPL), peripapillary retinal nerve fiber layer (pRNFL) thickness, and ONH parameters using optical coherence tomography. Results. The average of five out of six sectors and minimum values of mGCIPL thicknesses in eyes with prominent β-PPA discs were significantly less than those of the control eyes. The results of clock-hour sector analyses showed significant differences for pRNFL thickness in one sector. In the ONH analyses, no significant difference was observed between myopic β-PPA and control eyes. The macular thickness of the β-PPA eyes was thinner than control eyes in all sectors. There was a significant difference between the two groups in three sectors (the inner superior macula, inner temporal macula, and inner inferior macula) but there was no significant difference in the other sectors, including the fovea. Conclusions. The myopic β-PPA eyes showed thinner mGCIPL, parafovea, and partial pRNFL layers compared with myopic eyes without β-PPA.

Visual Field Progression Pattern Associated With Optic Disc Tilt Morphology in Myopic Open-Angle Glaucoma

PURPOSE

To understand the long-term characteristics of visual field (VF) progression in myopic open-angle glaucoma (OAG) according to the morphology of optic disc tilt.

DESIGN

Retrospective, comparative, longitudinal cohort study.

METHODS

Myopic OAG eyes were divided into temporally tilted disc and inferiorly tilted disc groups according to optic disc torsional degrees. Kaplan-Meier survival analysis was used to compare the survival rates between nonmyopic OAG, myopic OAG with temporally tilted disc, and myopic OAG with inferiorly tilted disc. The hazard ratio (HRs) for the associations between risk factors and progression were analyzed using Cox proportional hazards modeling. In the inferiorly tilted disc group, subgroups were classified into progression, stationary, and progression-to-stationary groups, and the clinical characteristics of VF progression were compared among the subgroups.

RESULTS

A total of 82 eyes in 82 nonmyopic OAG patients and 150 eyes in 150 myopic OAG patients were included. Myopic OAG with inferiorly tilted disc showed significantly more baseline and final 1-hemifield-involvement cases compared with myopic OAG with temporally tilted disc (P < .001, P < .001, respectively). The cumulative probability of progression was shown to be faster for myopic OAG with inferiorly tilted disc compared with temporally tilted disc and nonmyopic OAG (P = .002, P = .038, respectively). A larger number of medications (HR = 1.339; P = .004), earlier-stage VF defect (HR = 1.217; P < .001), and inferiorly tilted disc (HR = 2.378; P < .001) were predictive of progression. In the analysis of myopic OAG with inferiorly tilted disc, the progression group had younger age and earlier-stage VF defect at baseline compared with the stationary group (P = .01, P < .001, respectively).

CONCLUSIONS

It is likely that VF progression in myopic OAG is associated with the morphology of the optic disc tilt. Especially in OAG with inferiorly tilted disc, VF is likely not to progress after terminating VF progression at the region associated with optic disc tilt.

Association of Myopic Optic Disc Deformation with Visual Field Defects in Paired Eyes with Open-Angle Glaucoma: A Cross-Sectional Study

PURPOSE

To examine the association of myopia with the visual field (VF) defects in open-angle glaucoma (OAG) using paired eyes to eliminate the effect of unknown confounding factors that are diverse among individuals.

METHODS

One hundred eighteen eyes of 59 subjects with myopia (spherical equivalent [SE] ≥ -2 diopter [D] and axial length ≥ 24.0 mm) whose intra-ocular pressure between paired eyes was similar and the mean deviation (MD) of the Humphrey VF test differed by more than 6 dB were included. Refractive errors (SE, axial length) and parameters associated with the papillary and parapapillary myopic deformation (tilt ratio, torsion angle, and β-zone parapapillary atrophy [PPA] area without Bruch's membrane) were measured in each eye. The paired eyes were divided into worse and better eyes according to the MD of the VF, and parameters were compared between them. Further, multiple linear regression analysis was performed to examine the correlation of the difference in various parameters with the MD difference between paired eyes.

RESULTS

The SE of all eyes was -6.39 ± 2.15 D (mean ± standard deviation) and axial length was 26.42 ± 1.07 mm. MD of the worse and better VF eyes were -13.56 ± 6.65 dB and -4.87 ± 5.32 dB, respectively. Eyes with worse VFs had significantly greater SE, axial length, tilt ratio, and PPA area without Bruch's membrane than those with better VFs (all P < 0.05). In multiple linear regression analysis, the difference of the MD between paired eyes was significantly correlated with the difference in the tilt ratio and PPA area without Bruch's membrane.

CONCLUSION

The myopic papillary and parapapillary deformations, but not refractive error itself, were related to the worse VF in paired eyes with OAG. This suggests that myopia influences the severity of the glaucomatous VF defects via structural deformation.