TEMPORAL VASCULAR ARCADE WIDTH AND ANGLE IN HIGH AXIAL MYOPIA

How is eyeball growth associated with optic nerve head shape and glaucoma? The Lamina cribrosa/Bruch's membrane opening offset theory

The optic nerve head (ONH) is a complex structure wherein the axons of the retinal ganglion cells extrude from the eyeball through three openings: 1) the Bruch's membrane opening (BMO) in the retinal layer, 2) the anterior scleral canal opening in the anterior scleral layer, and 3) the lamina cribrosa (LC). Eyeball expansion during growth induces an offset among openings, since the expansion affects the inner retinal and outer scleral layers differently: the posterior polar retinal structure is preserved by the preferential growth in the equatorial region, whereas no such regional difference is observed in the scleral layer. The various modes and extents of eyeball expansion result in diverse directionality and amount of offset among openings, which causes diverse ONH morphology in adults, especially in myopia. In this review, we summarize the ONH changes that occur during myopic axial elongation. These changes were observed prospectively in our previous studies, wherein LC shift and subsequent offset from the BMO center could be predicted by tracing the central retinal vascular trunk position. This offset induces the formation of γ-zone parapapillary atrophy or externally oblique border tissue. As a presumptive site of glaucomatous damage, the LC/BMO offset may render the LC pores in the opposite direction more vulnerable. To support such speculation, we also summarize the relationship between LC/BMO offset and glaucomatous damage. Indeed, LC/BMO offset is not only the cause of diverse ONH morphology in adults, but is also, potentially, an important clinical marker for assessment of glaucoma.

Antioxidants and Mechanistic Insights for Managing Dry Age-Related Macular Degeneration

Age-related macular degeneration (AMD) severely affects central vision due to progressive macular degeneration and its staggering prevalence is rising globally, especially in the elderly population above 55 years. Increased oxidative stress with aging is considered an important contributor to AMD pathogenesis despite multifaceted risk factors including genetic predisposition and environmental agents. Wet AMD can be managed with routine intra-vitreal injection of angiogenesis inhibitors, but no satisfactory medicine has been approved for the successful management of the dry form. The toxic carbonyls due to photo-oxidative degradation of accumulated bisretinoids within lysosomes initiate a series of events including protein adduct formation, impaired autophagy flux, complement activation, and chronic inflammation, which is implicated in dry AMD. Therapy based on antioxidants has been extensively studied for its promising effect in reducing the impact of oxidative stress. This paper reviews the dry AMD pathogenesis, delineates the effectiveness of dietary and nutrition supplements in clinical studies, and explores pre-clinical studies of antioxidant molecules, extracts, and formulations with their mechanistic insights.

Retinal Changes From Hyperopia to Myopia: Not All Diopters Are Created Equal

Purpose

To quantitatively characterize retinal changes across different quantiles of refractive error in 34,414 normal eyes of 23,064 healthy adults in the UK Biobank.

Methods

Twelve optic disc (OD), foveal and vascular parameters were derived from color fundus photographs, correcting for ocular magnification as appropriate. Quantile regression was used to test the independent associations between these parameters and spherical equivalent refraction (SER) across 34 refractive quantiles (high hyperopia to high myopia)-controlling for age, sex and corneal radius.

Results

More negative SER was nonlinearly associated with greater Euclidian (largely horizontal) OD-fovea distance, larger OD, less circular OD, more obliquely orientated OD (superior pole tilted towards the fovea), brighter fovea, lower vascular complexity, less tortuous vessels, more concave (straightened out towards the fovea) papillomacular arterial/venous arcade and wider central retinal arterioles/venules. In myopia, these parameters varied more strongly with SER as myopia increased. For example, while every standard deviation (SD) decrease in vascular complexity was associated with 0.63 D (right eye: 95% confidence interval [CI], 0.58-0.68) to 0.68 D (left eye: 95% CI, 0.63-0.73) higher myopia in the quantile corresponding to -0.60 D, it was associated with 1.61 D (right eye: 95% CI, 1.40-1.82) to 1.70 D (left eye: 95% CI, 1.56-1.84) higher myopia in the most myopic quantile. OD-fovea angle (degree of vertical separation between OD and fovea) was found to vary linearly with SER, but the magnitude was of little practical importance (less than 0.10 D variation per SD change in angle in almost all refractive quantiles) compared with the changes in OD-fovea distance.

Conclusions

Several interrelated retinal changes indicative of an increasing (nonconstant) rate of mechanical stretching are evident at the posterior pole as myopia increases. These changes also suggest that the posterior pole stretches predominantly in the temporal horizontal direction.

Prevalence and Associations of Nonglaucomatous Optic Nerve Atrophy in High Myopia: The Ural Eye and Medical Study

PURPOSE

To assess the prevalence of nonglaucomatous optic nerve atrophy (NGOA) in highly myopic individuals.

DESIGN

Population-based study.

PARTICIPANTS

The Ural Eye and Medical Study included 5899 (80.5%) of 7328 eligible individuals (80.5%).

METHODS

Nonglaucomatous optic nerve atrophy, graded into 5 arbitrary stages, was characterized by decreased visibility of the retinal nerve fiber layer (RNFL) on photographs, neuroretinal rim pallor, abnormally thin retinal arteriole diameter, and abnormally thin peripapillary RNFL as measured by OCT.

MAIN OUTCOME MEASURES

Nonglaucomatous optic nerve atrophy prevalence and degree.

RESULTS

Of 5709 participants (96.9%) with axial length measurements, 130 individuals (2.3%) were highly myopic, of whom 116 individuals (89.2%; age, 57.8 ± 11.1 years; axial length, 27.0 ± 1.2 mm) had available fundus photographs and OCT images and were included into the study. Nonglaucomatous optic nerve atrophy prevalence was 34/116 individuals (29.3%; 95% confidence interval [CI], 21.0-38.0), and mean NGOA degree in eyes with NGOA was 1.7 ± 1.0 arbitrary units. Higher NGOA degree correlated (multivariable analysis; regression coefficient, r2 = 0.59) with longer axial length (β, 0.22; P = 0.007), wider temporal parapapillary γ zone width (β, 0.50; P < 0.001), higher prevalence of diabetes (β, 0.20; P = 0.005), and higher systolic blood pressure (β, 0.15; P = 0.03). Higher NGOA prevalence was associated with longer axial length (odds ratio [OR], 7.45; 95% CI, 2.15-25.7), wider temporal parapapillary γ zone (OR, 6.98; 95% CI, 2.61-18.7), and higher systolic blood pressure (OR, 1.05; 95% CI, 1.01-1.10).

CONCLUSIONS

In this ethnically mixed population from Russia with an age of 40 years or more, high axial myopia showed a relatively high prevalence of NGOA, increasing with longer axial length and wider temporal parapapillary γ zone. For each 1 mm of axial elongation and γ zone widening, the odds for NGOA increased 7.45-fold and 6.98-fold, respectively. The axial elongation-associated and γ zone-related increase in the distance between the retinal ganglion cells and the optic disc may lead to a lengthening and stretching of the retinal ganglion cell axons and may be of importance pathogenetically. In highly myopic eyes, NGOA may be a reason for visual field and central visual acuity loss, unexplainable by myopic macular pathologic features.

FINANCIAL DISCLOSURE(S)

Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.

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

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

Retinal Artery Angles in High Axial Myopia and Its Relationship With Visual Function

Purpose

To evaluate the retinal artery angles in high axial myopia and assess the correlation with other morphometric and functional parameters.

Methods

This cross-sectional study included 112 eyes of 112 patients with high axial myopia. Based on axial length (AL), the participants were divided into three groups: group 1 (26 ≤ AL < 28 mm), group 2 (28 ≤ AL < 31 mm), and group 3 (≥31 mm). Scanning laser ophthalmoscopy imaging was used to analyze the retinal artery angle (Yugami correlated angle [YCA]). Retinal vascular densities (VDs) in both superficial capillary plexuses (SCPs) and deep capillary plexuses were evaluated. Fixation behavior, including retinal mean sensitivity (MS), macular fovea 2°, 4° fixation rate (P1, P2), and 68.2% bivariate contour ellipse area, were analyzed by microperimetry. Finally, the correlation between YCAs and AL, VDs, best-corrected visual acuity (BCVA), and fixation behavior was assessed.

Results

The YCAs showed significant differences among the three groups (all P < 0.001, respectively). Compared to group 1, the YCA decreased in group 2 (P < 0.001) and continued to decrease in group 3 (P = 0.043). The correlation analysis revealed that smaller YCAs (YCA, YCA1/2, YCA1/4) were positively correlated with the longer AL (ρ = 0.580, 0.545, 0.448, P < 0.001) and lower VDs in any sector in SCPs (all P ≤ 0.05). Furthermore, smaller YCAs were positively correlated with decreased BCVA (ρ = 0.392, 0.387, 0.262; all P < 0.001) and reduced MS (ρ= 0.300, 0.269, 0.244; all P < 0.05).

Conclusions

Smaller YCAs were correlated with longer AL, lower VD in SCP, decreased BCVA, and reduced MS. The YCAs might reflect vascular deformation caused by axial elongation and could potentially be useful in predicting visual function in high axial myopia.

Translational Relevance

The quantitative analysis of YCAs in fundus photography holds potential clinical value in predicting visual function in high axial myopia.

Differences in structural parameters in patients with open-angle glaucoma, high myopia and both diseases concurrently. A pilot study

PURPOSE

To evaluate the differences in structural parameters in patients with open-angle glaucoma (OAG), high myopia (M), and both diseases (OAG-M) concurrently.

METHODS

42 subjects with OAG (n = 14), M (n = 14) and OAG-M (n = 14) were included in a prospective pilot study. Mean peripapillary retinal nerve fiber layer (RNFL) thickness, RNFL in superior, temporal, inferior, nasal quadrants, macular ganglion cell complex (GCC) and its' layers, vessel density (VD) of optic nerve head (ONH) and macula were evaluated.

RESULTS

The OAG-M group showed significantly lowest thickness of mean peripapillary RNFL 89 (49-103) μm (p = 0.021), temporal quadrant 64.5 (51-109) μm (p = 0.001) and inferior quadrant 107 (64-124) μm (p = 0.025). The macular RNFL was thinnest in the OAG-M group (p <0.001). Macular VD in inferior quadrant was lowest in OAG-M group at superficial capillary plexus 45.92 (40.39-51.72) % (p = 0.014) and choriocapillaris 51.62 (49.87-56.63) % (p = 0.035). The lowest ONH VD of temporal quadrant was found in the OAG-M group 52.15 (35.73-59.53) % (p = 0.001) in the superficial capillary plexus. Similarly, the lowest VD of inferior quadrant was found in OAG-M group in the choriocapillaris 54.42 (46.31-64.64) % (p<0.001).

CONCLUSIONS

The M group showed the least thinning in the peripapillary RNFL thickness in the temporal quadrant and macular RNFL compared to other two groups. The highest macular VD in the inferior quadrant was in the M group in the superficial capillary plexus, deep capillary plexus and choriocapillaris. The M group showed highest VD in the temporal quadrant and in total VD of ONH at the superficial capillary plexus and in total VD of ONH at the deep capillary plexus.

PRACTICAL RECOMMENDATIONS

The observed decrease in peripapillary RNFL thickness of the temporal quadrant, macular RNFL thickness, the decrease of macular VD at the inferior quadrant and decrease in VD of the ONH temporal quadrant in deep capillary plexus could be beneficial for diagnosing glaucoma in high myopia.

Morphology and microcirculation changes of the optic nerve head between simple high myopia and pathologic myopia

PURPOSE

To investigate morphological and microcirculation changes of optic nerve head (ONH) in simple high myopia (SHM) and pathologic myopia(PM) to evaluate and identify ONH changes in the development of PM.

METHODS

A cross-sectional clinical study was used. Medical records from 193 right eyes of 193 patients with high myopia (HM) were included. Using the Topocon swept source optical coherence tomograph (SS-OCT) and fundus camera to detect the parameters, we have assessed the relative position and size of ONH, tilt and rotation of ONH, angle α (Defined as between retinal temporal arterial vascular arcades was measured from the centre of ONH with 250 pixels' radius), size and type of peripapillary atrophy (PPA), the thickness of peripapillary retinal nerve fiber layer (PRNFL), peripapillary choriodal thickness (PCT) and peripapillary scleral thickness (PST), and peripapillary vessel density (PVD). In addition, subjects were grouped as SHM and PM according to retinopathy, and the above parameters were compared between the two groups.

RESULTS

Patients were divided into the SHM group (138 eyes) and the PM group (55 eyes). Paramters like older age, higher diopter and longer axial length (AL) of the PM were compared to SHM (t=-3.585, -8.808, -11.409, all P<0.05). There were no differences in the smallest diameter and area of ONH, rotation angle and ratio, or PST (all P>0.05). The angle α in PM was smaller than that in SHM (t = 2.728, P<0.01). The disc-fovea distance (DFD), the largest diameter, tilt index and ratio, PPA area and radian in PM were larger than in SHM (t=-3.962, Z=-2.525, t=-2.229, Z=-4.303, Z=-2.834, all P<0.05). The superior and inferior PRNFLs in PM were smaller than in SHM (t = 4.172, 4.263, all P<0.01). The temporoinferior PRNFL was the opposite (t=-2.421, P<0.01). The average PCT in PM (93.82 ± 29.96 μm) was smaller than in SHM (108.75 ± 30.70 μm) (P<0.05). The PVD in each direction of PM was smaller than that in SHM (t = 6.398, 4.196, 4.971, 3.267, 5.029, 5.653, 4.202, 5.146, 2.090, all P<0.05).

CONCLUSION

Compared with SHM, the PM patients were older, with higher diopter. Their AL and DFD were longer, the angle α was smaller, the tilt index was more extensive, the PPA area and radian were larger, PCT was generally thinner, and PVD was lower. When the PPA area was bigger than the ONH area, this already indicated the presence of PM. Based on these results, we suggest ophthalmologists and myopia patients pay more attention to ONH's morphology and microcirculation changes as there is a possibility that microcirculatory changes precede morphologic changes.

Longitudinal Changes in Peripapillary Retinal Nerve Fiber Layer and Macular Ganglion Cell Inner Plexiform Layer in Progressive Myopia and Glaucoma Among Adolescents

Purpose

This study aimed to investigate the differences in longitudinal changes in the peripapillary retinal nerve fiber layer (pRNFL) and macular ganglion cell plus inner plexiform layer (GCIPL) caused by progressive myopia and glaucoma among adolescents.

Design

This was a retrospective observational study.

Methods

A total of forty-seven and 25 eyes of 47 and 25 adolescents with myopia progression (MP) and glaucoma progression (GP), respectively, who were followed up at the Zhongshan Ophthalmic Center for at least 3 years, were included in the study. The pRNFL and GCIPL that measured at the initial and last visits were analyzed.

Results

The median follow-up period was 5 years for both two groups. During follow-up, the whole, superior, and inferior pRNFL decreased in both the MP and GP groups, (p < 0.001). Nasal pRNFL decreased in the MP group (p < 0.001) but had no significant difference in the GP group (p = 0.19). Temporal pRNFL was increased in the MP group (p < 0.001) but decreased in the GP group (p < 0.001). The average and sectoral GCIPL decreased in both groups (p < 0.001). The annual change rate of temporal pRNFL and pRNFL at 10-, 8-, 9-, and 7-clock-hour sectors and the inferotemporal GCIPL has better diagnostic value to differentiate glaucoma from myopia (the area under the receiver operating characteristic curve, AUC > 0.85).

Conclusion

Glaucoma and MP could cause loss of the pRNFL and GCIPL in adolescents; however, the loss patterns were different between the two groups. The temporal quadrant and 7-, 8-, 9-, and 10-clock-hour sector pRNFL and the inferotemporal GCIPL can help distinguish pRNFL and GCIPL loss caused by glaucoma or MP.

Choriocapillaris Flow Deficits in Normal Chinese Imaged by Swept-Source Optical Coherence Tomographic Angiography

PURPOSE

To evaluate the ocular and systemic determinants of the choriocapillaris flow deficits percentage (CC FD%) in normal eyes.

DESIGN

Observational cross-sectional study.

METHODS

Healthy Chinese participants without ocular or systemic diseases underwent detailed ophthalmic evaluations, including swept-source optical coherence tomography angiography (SS-OCTA) with 6- × 6-mm macular choriocapillaris images. The CC FD% was assessed in circular regions with diameters of 1.0 and 5.0 mm, rings with 1.0- to 2.5-mm diameters, and rings with 2.5- to 5.0-mm diameters.

RESULTS

The study included 830 individuals (mean ± SD age 58.66 ± 8.75 years). CC FD% (mean ± SD 22.05% ± 1.13%) was the lowest in the 2.5- to 5.0-mm ring, followed by the 1.0- to 2.5-mm ring, and highest in the 1.0-mm circle. In multivariable analysis, a higher CC FD% was associated with older age (β = 0.16 [95% confidence interval {CI}] 0.08-0.24, P < .001), higher intraocular pressure (β = 0.34 [95% CI 0.25-0.42], P < .001), higher serum concentrations of high-density lipoprotein cholesterol (β = 0.24 [95% CI 0.17-0.32], P < .001), and lower image quality score (β = -0.22 [95% CI -0.30 to -0.14], P < .001). CC FD% was also independent of axial length.

CONCLUSIONS

In healthy adult Chinese individuals, a higher CC FD% was associated with older age, higher intraocular pressure, and higher high-density lipoprotein cholesterol serum concentration. These factors may influence clinical assessments of the choriocapillaris. The lack of an association between CC FD% and axial length is consistent with similar findings for Bruch membrane thickness, macular retinal thickness, and macular retinal pigment epithelium cell density.

Morphological characteristics of retinal vessels in eyes with high myopia: Ultra-wide field images analyzed by artificial intelligence using a transfer learning system

Purpose

The purpose of this study is to investigate the retinal vascular morphological characteristics in high myopia patients of different severity.

Methods

317 eyes of high myopia patients and 104 eyes of healthy control subjects were included in this study. The severity of high myopia patients is classified into C0-C4 according to the Meta Analysis of the Pathologic Myopia (META-PM) classification and their vascular morphological characteristics in ultra-wide field imaging were analyzed using transfer learning methods and RU-net. Correlation with axial length (AL), best corrected visual acuity (BCVA) and age was analyzed. In addition, the vascular morphological characteristics of myopic choroidal neovascularization (mCNV) patients and their matched high myopia patients were compared.

Results

The RU-net and transfer learning system of blood vessel segmentation had an accuracy of 98.24%, a sensitivity of 71.42%, a specificity of 99.37%, a precision of 73.68% and a F1 score of 72.29. Compared with healthy control group, high myopia group had smaller vessel angle (31.12 ± 2.27 vs. 32.33 ± 2.14), smaller fractal dimension (Df) (1.383 ± 0.060 vs. 1.424 ± 0.038), smaller vessel density (2.57 ± 0.96 vs. 3.92 ± 0.93) and fewer vascular branches (201.87 ± 75.92 vs. 271.31 ± 67.37), all P < 0.001. With the increase of myopia maculopathy severity, vessel angle, Df, vessel density and vascular branches significantly decreased (all P < 0.001). There were significant correlations of these characteristics with AL, BCVA and age. Patients with mCNV tended to have larger vessel density (P < 0.001) and more vascular branches (P = 0.045).

Conclusion

The RU-net and transfer learning technology used in this study has an accuracy of 98.24%, thus has good performance in quantitative analysis of vascular morphological characteristics in Ultra-wide field images. Along with the increase of myopic maculopathy severity and the elongation of eyeball, vessel angle, Df, vessel density and vascular branches decreased. Myopic CNV patients have larger vessel density and more vascular branches.

Factors associated with axial length elongation in high myopia in adults

AIM

To investigate the association of axial length (AL) and ocular factors on AL elongation.

METHODS

A retrospective chart review of patients who underwent two or more AL examinations for more than two years. Totally 4 groups were divided according to initial AL (<24 mm, 24-26 mm, 26-28 mm, ≥28 mm). Initial fundus photograph was used to find risk factors associated AL elongation.

RESULTS

The mean age of the patients was 47.21±7.79y. AL remained almost unchanged in the groups with AL<24 mm and 24≤AL<26 mm. On the contrary, AL increased by 0.011 mm/y in the group with 26≤AL<28 mm and 0.035 mm/y in the group with AL≥28 mm (P<0.001). In high myopia, AL elongation increased in eye with longer AL (r=0.003, P=0.024), female gender (r=0.014, P=0.019), eye with larger peripapillary chorioretinal atrophic area (r=0.002, P=0.019), and smaller vascular arcade angle (r=-0.004, P=0.006). The risk of elongation 0.03 mm/y in high myopia was increased in female gender (P=0.040), and gradually increased in eye with large peripapillary chorioretinal atrophy area (P<0.01).

CONCLUSION

AL elongate significantly in the eye with longer AL, female gender, and the eye with larger atrophic area and smaller arcade angle on fundus photography.

PROGRESSION OF MYOPIC MACULOPATHY IN CHINESE CHILDREN WITH HIGH MYOPIA: A Long-Term Follow-Up Study

PURPOSE

To investigate the progression of myopic maculopathy and associated factors in highly myopic Chinese children.

METHODS

In this retrospective observational case series, biometric fundus features were morphometrically measured on photographs. Myopic maculopathy was defined as recommended by the Meta-analysis of Pathologic Myopia Study Group.

RESULTS

The study included 274 children (mean age: 11.7 ± 2.5 years; mean refractive error: -7.66 ± 1.87 diopters [D]) with a mean follow-up of 4.9 ± 1.2 years. Myopic maculopathy progression was detected in 52 eyes (18.9%; 95% confidence interval [CI]: 14.3-23.7%). In multivariable analysis, myopic maculopathy progression was associated with a decrease in refractive error (odds ratio [OR]: 0.72; 95% CI: 0.56-0.92; P < 0.001) (i.e., higher myopization) and enlargement of parapapillary gamma zone (OR: 7.68; 95% CI: 1.63-36.2; P = 0.002). Incident peripapillary diffuse choroidal atrophy, noted in 47 of 236 eyes (20.0%; 95% CI: 14.8-25.2%), was correlated with a decrease in refractive error (OR: 0.70; 95% CI: 0.54-0.92; P = 0.009) (i.e., higher myopization) and greater gamma zone enlargement (OR: 8.28; 95% CI: 1.33-51.7; P = 0.02).

CONCLUSION

Myopia in schoolchildren may have a considerable risk of progressing to myopic maculopathy. Enlargement of parapapillary gamma zone was a main independent risk factor.

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

Purpose

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

Methods

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

Results

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

Conclusions

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

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

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

Peaks of circumpapillary retinal nerve fibre layer and associations in healthy eyes: the Beijing Eye Study 2011

AIMS

To investigate the distribution and associations of the circumpapillary retinal nerve fibre layer thickness (RNFLT) profile, characterised as peak height and peak position, in healthy eyes.

METHODS

667 healthy participants (294 male) were randomly selected from the Beijing Eye Study 2011. RNFLT was measured at 768 points at 3.4 mm circumpapillary position using spectral-domain optical coherence tomography (OCT). The location and height of the superior temporally peak (Peak^ST), superior nasal peak (Peak^SN) and inferior temporal peak (Peak^IT) were assessed.

RESULTS

The RNFLT was thickest at Peak^IT (194±25 µm; location: 288±12°), followed by Peak^ST (182±25 µm; 73±10°) and Peak^SN (125±23 µm; 135°±13°). In multivariable analysis, peak RNFLT decreased with longer axial length (p<0.001; correlation coefficient beta: -0.18 to -0.15; all peaks), older age (all p<0.01, beta: -0.10; Peak^ST and Peak^IT), female gender (p=0.026, beta: -0.09; Peak^ST), and larger parapapillary gamma zone and beta zone width (p≤0.004, beta: -0.16 to-0.11; Peak^SN). The temporal peaks were located more closely to the horizontal line in women (p≤0.020, beta: 0.09-0.11) and with longer axial length (p<0.001, beta: 0.27-0.31), while they were located more inferiorly in eyes with larger Bruch's membrane openings (BMOs) (p≤0.01, beta:0.10~0.11).

CONCLUSIONS

Peak RNFLT decreased by 0.34 µm for each increase of year in age (Peak^ST and Peak^IT), by 3.2-3.5 µm for each 1 mm increase in axial length (all three peaks), and was 4.5 µm thinner in women than in men. The position of temporal peaks depended on gender, axial length and BMO diameter. These associations should be taken into count in OCT-based RNFLT assessment for disease finding, especially in glaucoma evaluation.

Posterior staphyloma is associated with the microvasculature and microstructure of myopic eyes

Objective

To investigate the microvasculature and structural characteristics of the eyes of myopic patients and their association with posterior staphyloma (PS).

Methods

This was a retrospective, case-control study comprising of 106 eyes from 72 individuals. Using 1:1 matching of axial length (AL) of their eyes, patients were allocated into a PS group or no posterior staphyloma (NPS) group. All patients were examined using ultra-widefield fundus imaging, optical coherence tomography angiography, and ocular biometry to acquire microvasculature and microstructure parameters.

Results

The anterior chamber depth (ACD) of the PS group was significantly different from that of the NPS group (3.56 mm vs 3.76 mm, P < 0.001), as was 1ens thickness (3.72 mm vs 3.57 mm, P = 0.005) and spherical equivalent (SE)(-10.11D vs -8.80D, P = 0.014). The PS group had reduced choriocapillaris flow, subfoveal choroidal thickness (SFCT), and a thinner retinal layer compared with the NPS group. No difference in retinal blood flow between the two groups was observed. The PS group exhibited a smaller disc area (15082.89 vs 17,043.32, P = 0.003) and angle α between temporal retinal arterial vascular arcades (113.29°vs 128.39°, P = 0.003), a larger disc tilt ratio (1.41 vs 1.24, P < 0.001) and parapapillary atrophy (PPA) area (13840.98 vs 8753.86, P = 0.020), compared with the NPS group. Multivariate regression analysis indicated that disc tilt ratio (P = 0.031) and SFCT (P = 0.015) were significant predictors of PS. In addition, PS (P = 0.049), AL (P = 0.003), corneal refractive power (P < 0.001), ACD (P = 0.022), relative lens position (P = 0.045), and disc area (P = 0.011) were significant predictors of SE.

Conclusions

PS was found to be closely linked to a reduction in choriocapillaris perfusion and anatomical abnormalities including posterior and anterior segments. Furthermore, PS exacerbated the progression of myopia.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00417-020-05057-0.

Advances in myopia research anatomical findings in highly myopic eyes

BACKGROUND

The goal of this review is to summarize structural and anatomical changes associated with high myopia.

MAIN TEXT

Axial elongation in myopic eyes is associated with retinal thinning and a reduced density of retinal pigment epithelium (RPE) cells in the equatorial region. Thickness of the retina and choriocapillaris and RPE cell density in the macula are independent of axial length. Choroidal and scleral thickness decrease with longer axial length in the posterior hemisphere of the eye, most marked at the posterior pole. In any eye region, thickness of Bruch's membrane (BM) is independent of axial length. BM opening, as the inner layer of the optic nerve head layers, is shifted in temporal direction in moderately elongated eyes (axial length <26.5 mm). It leads to an overhanging of BM into the intrapapillary compartment at the nasal optic disc side, and to an absence of BM at the temporal disc border. The lack of BM at the temporal disc side is the histological equivalent of parapapillary gamma zone. Gamma zone is defined as the parapapillary region without BM. In highly myopic eyes (axial length >26.5 mm), BM opening enlarges with longer axial length. It leads to a circular gamma zone. In a parallel manner, the peripapillary scleral flange and the lamina cribrosa get longer and thinner with longer axial length in highly myopic eyes. The elongated peripapillary scleral flange forms the equivalent of parapapillary delta zone, and the elongated lamina cribrosa is the equivalent of the myopic secondary macrodisc. The prevalence of BM defects in the macular region increases with longer axial length in highly myopic eyes. Scleral staphylomas are characterized by marked scleral thinning and spatially correlated BM defects, while thickness and density of the choriocapillaris, RPE and BM do not differ markedly between staphylomatous versus non-staphylomatous eyes in the respective regions.

CONCLUSIONS

High axial myopia is associated with a thinning of the sclera and choroid posteriorly and thinning of the retina and RPE density in the equatorial region, while BM thickness is independent of axial length. The histological changes may point towards BM having a role in the process of axial elongation.

Measurements of the parapapillary atrophy area and other fundus morphological features in high myopia with or without posterior staphyloma and myopic traction maculopathy

AIM

To investigate the affecting factors of parapapillary gamma and delta zones and other fundus morphological features in high myopia.

METHODS

Seventy high myopia patients were included in this retrospective observational study and 47 patients were female. Patients were divided into three groups: no posterior staphyloma (no PS), PS with myopic traction maculopathy (PS with MTM), and PS without MTM using 3-dimensional magnetic resonance imaging and optical coherence tomography. MTM patients were further classified into three types [epiretinal membrane, macular hole, and macular retinoschisis (MRS)]. Diameters of the gamma and delta zones were measured among other morphometric variables using fundus photographs.

RESULTS

Of the 70 individuals (127 eyes), the mean age was 57.46±13.56y. In univariate analysis, morphological features changed most dramatically in PS with MTM patients, who had the largest gamma zone diameters, the largest disk-fovea distance (DFD) and disk-fovea angle, and the smallest angle kappa and vertical distance of temporal arterial arcade. However, their horizontal delta zone diameter was smaller than in the patients with PS yet without MTM. In multivariate analysis, with axial length (AL) and age adjusted, the horizontal diameter in the delta zone of the PS without MTM group was still significantly larger than in the PS with MTM group (P=0.024). Comparing the three subtypes of MTM patients, the diameters of the gamma zone and DFD in MRS group were the largest.

CONCLUSION

The characteristics of the gamma and delta zones change inconsistently in different stages of high myopia. These changes may be associated with anatomical changes caused by local traction. Factors such as PS, AL and age play an important role. These findings may provide a hint about the pathogenesis of traction in high myopia.

Association between morphological characteristics of the optic disc and other anatomical features of the fundus in highly myopic eyes

PURPOSE

To investigate associated factors with optic disc characteristics in high myopia patients.

METHODS

According to the meta-analysis of pathologic myopia study, patients were divided into groups from categories 1 (C1) to C4. The diameters, tilt ratio, and rotation degree of optic disc, and the diameters of parapapillary atrophy were measured among other morphometric variables.

RESULTS

Totally 147 eyes (84 patients) were included. Longer horizontal optic disc diameter was associated with smaller tilt ratio (p < 0.001, unstandardized regression coefficient B: -0.59), greater rotation degree (p < 0.001, B: 0.01), and longer horizontal delta zone diameter (p < 0.001, B: 0.09). Longer vertical optic disc diameter was associated with smaller rotation degree (p < 0.001, B: 0.01), longer vertical delta zone diameter (p < 0.001, B: 0.16), and longer disc-fovea distance (DFD; p < 0.024, B: 0.14). Generally, the horizontal optic disc diameter of C3 and C4 groups was smaller than C1 and C2, while vertical diameter and tilt ratio was greater than in C1 and C2. After setting axial length (AL) as an independent variable, horizontal diameters and tilt ratio still showed significant differences, while vertical diameters did not show significant differences.

CONCLUSION

Axial elongation was associated with an increase of vertical optic disc diameter that was correlated with an reduction of optic disc rotation degree. By contrast, horizontal optic disc diameter elongation was correlated with an reduction of optic disc tilt ratio and an increase of optic disc rotation degree, which was independent of axial elongation.

Glaucoma in myopia: diagnostic dilemmas

Myopic eyes have an increased risk of glaucoma. However, glaucomatous changes in a myopic eye are often difficult to detect. Classic structural and functional investigations to diagnose glaucoma may be confounded by myopia. Here, we identify some of the common pitfalls in interpreting these structural parameters, and the possible solutions that could be taken to overcome them. For instance, in myopic eyes, we discuss the limitations and potential sources of error when using neuroretinal rim parameters, and retinal nerve fibre layer and ganglion cell-inner plexiform layer thickness measurements. In addition, we also review new developments and potential adjuncts in structural imaging such as the assessment of the retinal nerve fibre layer texture, and the examination of the microcirculation of the optic nerve head using optical coherence tomography angiography. For the functional assessment of glaucoma, we discuss perimetric strategies that may aid in detecting characteristic visual field defects in myopic glaucoma. Ultimately, the evaluation of glaucoma in myopia requires a multimodal approach, to allow correlation between structural and functional assessments. This review provides overview on how to navigate this diagnostic dilemma.