Racial differences in optic nerve head parameters

Optic Disc Size and Circumpapillary Retinal Nerve Fiber Layer Thinning in Glaucoma

PURPOSE

To investigate the association between optic disc size and circumpapillary retinal nerve fiber layer (cpRNFL) thinning in eyes with preperimetric glaucoma and glaucoma.

DESIGN

Observational cohort.

PARTICIPANTS

A total of 841 eyes (554 primary open angle glaucoma and 287 preperimetric glaucoma) from 553 patients who had at least 4 visits and 2 years of follow-up using OCT.

METHODS

Multivariable linear mixed-effects modeling was used to estimate the effect of optic disc size on cpRNFL thinning while controlling for covariates. To eliminate the floor effect, eyes with baseline visual field mean deviation less than -14 dB were excluded.

MAIN OUTCOME MEASURES

The effect of optic disc size on cpRNFL thinning.

RESULTS

Of the participants, 189 (34.2%) were Black, 338 (61.1%) were White, 20 (3.6%) were Asian, and 6 (1.1%) were another race or ethnicity. Mean follow-up period was 5.3 (95% confidence interval [CI], 5.2-5.5) years, and the mean rate of cpRNFL change was -0.54 (95% CI, -0.61 to 0.47) μm/year. After adjusting for covariates with the Littmann's formula correction, larger optic disc size was associated with faster cpRNFL thinning (-0.03; 95% CI, -0.05 to 0.00) μm/year faster per 0.1 mm2 larger; P = 0.034), while no significant differences were found for race and its interaction with optic disc size.

CONCLUSIONS

Larger optic disc size is associated with faster cpRNFL thinning in glaucoma, independent of race. Although previous studies have indicated that Black individuals may be at higher risk for glaucoma development, the present study suggests that race may not be a significant predictor of faster cpRNFL thinning when controlling for optic disc size and other clinical and demographic factors in glaucoma.

FINANCIAL DISCLOSURE(S)

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

Application of artificial intelligence in glaucoma care: An updated review

The application of artificial intelligence (AI) in ophthalmology has been increasingly explored in the past decade. Numerous studies have shown promising results supporting the utility of AI to improve the management of ophthalmic diseases, and glaucoma is of no exception. Glaucoma is an irreversible vision condition with insidious onset, complex pathophysiology, and chronic treatment. Since there remain various challenges in the clinical management of glaucoma, the potential role of AI in facilitating glaucoma care has garnered significant attention. In this study, we reviewed the relevant literature published in recent years that investigated the application of AI in glaucoma management. The main aspects of AI applications that will be discussed include glaucoma risk prediction, glaucoma detection and diagnosis, visual field estimation and pattern analysis, glaucoma progression detection, and other applications.

Features Associated with Visible Lamina Cribrosa Pores in Individuals of African Ancestry with Glaucoma: Primary Open-Angle African Ancestry Glaucoma Genetics (POAAGG) Study

There are scarce data regarding the rate of the occurrence of primary open-angle glaucoma (POAG) and visible lamina cribrosa pores (LCPs) in the eyes of individuals with African ancestry; the potential impact of these features on disease burden remains unknown. We recruited subjects with POAG to the Primary Open-Angle African American Glaucoma Genetics (POAAGG) study. Through regression models, we evaluated the association between the presence of LCPs and various phenotypic features. In a multivariable analysis of 1187 glaucomatous eyes, LCPs were found to be more likely to be present in eyes with cup-to-disc ratios (CDR) of ≥0.9 (adjusted risk ratio (aRR) 1.11, 95%CI: 1.04-1.19, p = 0.005), eyes with cylindrical-shaped (aRR 1.22, 95%CI: 1.11-1.33) and bean pot (aRR 1.24, 95%CI: 1.13-1.36) cups versus conical cups (p < 0.0001), moderate cup depth (aRR 1.24, 95%CI: 1.06-1.46) and deep cups (aRR 1.27, 95%CI: 1.07-1.50) compared to shallow cups (p = 0.01), and the nasalization of central retinal vessels (aRR 1.33, 95%CI: 1.23-1.44), p < 0.0001). Eyes with LCPs were more likely to have a higher degree of African ancestry (q0), determined by means of SNP analysis (aRR 0.96, 95%CI: 0.93-0.99, p = 0.005 for per 0.1 increase in q0). Our large cohort of POAG cases of people with African ancestry showed that LCPs may be an important risk factor in identifying severe disease, potentially warranting closer monitoring by physicians.

Racial Differences in the Diagnostic Accuracy of OCT Angiography Macular Vessel Density for Glaucoma

PURPOSE

To evaluate and compare the diagnostic accuracy of macular vessel density (VD) measured by OCT angiography (OCTA) in individuals of African descent (AD) and European descent (ED) with open-angle glaucoma.

DESIGN

Observational, cross sectional study.

PARTICIPANTS

A total of 176 eyes of 123 patients with glaucoma and 140 eyes of 88 healthy participants from the Diagnostic Innovations in Glaucoma Study.

METHODS

Whole-image ganglion cell complex (wiGCC) thickness and macular VD (parafoveal VD and perifoveal VD) were obtained from 6 × 6 macula scans. Area under the receiver operating characteristic (AUROC) curves were used to evaluate the diagnostic accuracy of macular VD and ganglion cell complex (GCC) thickness in AD and ED participants after adjusting for confounders such as age, visual field mean deviation (VF MD), signal strength index, axial length, self-reported hypertension and diabetes.

MAIN OUTCOME MEASURES

Macular VD and wiGCC measurements.

RESULTS

Parafoveal and perifoveal VD were significantly lower in ED than AD patients with glaucoma. Parafoveal and perifoveal VD performed significantly worse in AD participants compared with ED participants for detection of glaucoma (adjusted AUROC, 0.75 [95% confidence interval (CI), 0.62, 0.87], 0.85 [95% CI, 0.79, 0.90], P = 0.035; and 0.82 [95% CI, 0.70, 0.92], 0.91 [95% CI, 0.87, 0.94], respectively; P = 0.020). In contrast to VD, diagnostic accuracy of GCC thickness was similar in AD and ED individuals (adjusted AUROC, 0.89 [95% CI, 0.79, 0.96], 0.92 [95% CI, 0.86, 0.96], respectively; P = 0.313). The diagnostic accuracies of both macular VD and GCC thickness for differentiating between glaucoma and healthy eyes increased with increasing VF MD in both AD and ED participants.

CONCLUSIONS

Diagnostic performance of OCTA macular VD, but not GCC thickness, for glaucoma detection varies by race. Moreover, macular VD parameters had lower accuracy for detecting glaucoma in AD individuals than in ED individuals. The diagnostic performance of macular VD is race-dependent, and, therefore, race should be taken into consideration when interpreting macular OCTA results.

FINANCIAL DISCLOSURE(S)

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

Factors Associated with Large Cup-to-Disc Ratio and Blindness in the Primary Open-Angle African American Glaucoma Genetics (POAAGG) Study

BACKGROUND/AIMS

Primary open-angle glaucoma (POAG) disproportionately affects individuals of African ancestry. In these patients' eyes, a large cup-to-disc ratio (LCDR > 0.90) suggests greater retinal ganglion cell loss, though these patients often display varied visual ability. This study investigated the prevalence and risk factors associated with LCDR in African ancestry individuals with POAG and explored the differences between blind (>20/200) and not blind (≤20/200) LCDR eyes.

METHODS

A case-control methodology was used to investigate the demographic, optic disc, and genetic risk factors of subjects in the Primary Open-Angle African American Glaucoma Genetics Study. Risk factors were analyzed using univariable and multivariable logistic regression models with inter-eye correlation adjusted using generalized estimating equations.

RESULTS

Out of 5605 eyes with POAG, 1440 eyes (25.7%) had LCDR. In the multivariable analysis, LCDR was associated with previous glaucoma surgery (OR = 1.72), increased intraocular pressure (OR = 1.04), decreased mean deviation (OR = 1.08), increased pattern standard deviation (OR = 1.06), thinner retinal nerve fiber layer (OR = 1.05), nasalization of vessels (OR = 2.67), bayonetting of vessels (OR = 1.98), visible pores in the lamina cribrosa (OR = 1.68), and a bean-shaped cup (OR = 2.11). Of LCDR eyes, 30.1% were classified as blind (≤20/200). In the multivariable analysis, the statistically significant risk factors of blindness in LCDR eyes were previous glaucoma surgery (OR = 1.72), increased intraocular pressure (OR = 1.05), decreased mean deviation (OR = 1.04), and decreased pattern standard deviation (OR = 0.90).

CONCLUSIONS

These findings underscore the importance of close monitoring of intraocular pressure and visual function in African ancestry POAG patients, particularly those with LCDR, to preserve visual function.

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.

Racial Differences in Detection of Glaucoma Using Retinal Nerve Fiber Layer Thickness and Bruch Membrane Opening Minimum Rim Width

PURPOSE

To compare the sensitivities and specificities of the retinal nerve fiber layer thickness (RNFLT) and Bruch membrane opening minimum rim width (BMO-MRW) reference database-based criteria for detection of glaucoma in individuals of European descent (ED) and individuals of African descent (AD).

DESIGN

Comparative diagnostic analysis by race METHODS: 382 eyes of 255 glaucoma patients (ED = 170, AD = 85) and 94 eyes of 50 healthy individuals (ED = 30, AD = 20) with global and sectoral RNFLT and BMO-MRW measured with Spectralis optical coherence tomography (OCT) were included. Six diagnostic criteria were evaluated: global measurement below the 5th or 1st percentile, ≥1 of the 6 sector measurements below the 5th or 1st percentile, and superotemporal (ST) and/or inferotemporal (IT) measurement below the 5th or 1st percentile. The sensitivities and specificities of these measurements for detection of glaucoma were compared using bootstrapping methods.

RESULTS

ST and/or IT RNFLT below the 5th percentile has the best performance for detection of glaucoma among RNFLT classifications with a sensitivity (95% CI) of 89.5% (86.1, 92.5) and specificity of 87.2% (77.8, 95.1). In AD individuals, sensitivities of ST and IT RNFLT and BMO-MRW measurements below the 5th percentile criteria were lower than in ED individuals (RNFLT: 83.7% vs 92.5%, and BMO-MRW: 72.1% vs 88.5%, respectively), as well as specificities (AD RNFLT: 73.7% and BMO-MRW: 89.5% vs ED RNFLT: 96.4% and BMO-MRW: 98.2%, respectively).

CONCLUSIONS

RNFLT and BMO-MRW had consistently lower diagnostic performance in AD individuals compared with ED individuals. BMO-MRW criteria might fail to detect as many as one-third of eyes with glaucoma, specifically in AD individuals. With the current reference database, RNFLT, and especially BMO-MRW, criteria are not adequate for diagnosing glaucoma in AD individuals.

Central corneal thickness, axial length, anterior chamber and optic disc structure in patients with central and branch retinal vein occlusion

PURPOSE

To compare the central corneal thickness (CCT), the structural properties of the anterior chamber and optic disc in patients with central retinal vein occlusion (CRVO), branch retinal vein occlusion (BRVO), and controls.

MATERIAL AND METHODS

In this prospective study, 31 eyes of 31 CRVO patients (group 1) (mean age: 65.7 ± 10.2 male/female:16/15), 42 eyes of 42 BRVO patients (group 2) (mean age: 61.5 ± 9.9, male/female: 21/21), and 41 controls (mean age: 61.2 ± 15.3, male/female:15/26) were enrolled. Intraocular pressure (IOP), corrected IOP (IOPcorr), central corneal thickness (CCT), anterior chamber depth & volume (ACD & ACV), iridocorneal angle (ICA), axial length (AL), retinal nerve fiber layer (RNFL) thickness, ganglion cell layer (GCL) thickness, cup to disc ratio (C/D), cup & rim volume, the scleral canal diameter (SCD), and mean & pattern deviation in visual field of the eyes with CRVO/BRVO, their fellow eyes and control eyes were evaluated.

RESULTS

There was no significant difference in IOP among groups (p:0.239), while IOPcorr was significantly higher in eyes with CRVO compared with eyes with BRVO (p:0.003). Central corneal thickness was significantly thinner in CRVO than both BRVO and controls (p:0.005, p:0.002 respectively). The difference in the RNFL thickness was significant among groups (p:0.019), and it was detected significant between CRVO eyes and controls (p:0.05). Anterior chamber volume was lower in eyes with BRVO than in normal eyes (p:0.009). There was no significant difference in AL, ACD, rim volume, cup volume, GCL thickness, C/D ratio, ICA, and PSD among groups.

CONCLUSION

The patients with CRVO tend to have thinner corneas, and the evaluation of IOP and CCT can be overlooked during retinal follow-up. Intraocular pressure values corrected with CCT should always be take into account to prevent possible optic nerve damage.

An IRIS® Registry-Based Assessment of Primary Open-Angle Glaucoma Practice Patterns in Academic versus Non-Academic Settings

PURPOSE

To compare patient demographic data; level of severity; and clinical, diagnostic, and surgical practice patterns in patients with primary open-angle glaucoma (POAG) in an academic setting (AS) versus non-academic setting (NAS) using the American Academy of Ophthalmology IRIS® Registry (Intelligent Research in Sight).

METHODS

A retrospective cohort study of IRIS® Registry data that included patients with POAG who were seen between January 2016 and December 2019 and had at least one year of follow-up.

RESULTS

Of 3,707,084 distinct eyes with POAG, 3% (109,920) were included in the academic subcohort and 97% (3,597,164) were included in the non-academic subcohort. Among the findings of greatest note (P < .0001 for all comparisons) were a higher proportion of eyes of Black patients, a higher proportion of eyes with level 3 severity, and a higher mean cup-to-disc ratio in eyes in the AS. The relative frequency of gonioscopy, pachymetry, and visual field testing in conjunction with new patient visits was also notably higher in the AS. For glaucoma surgical procedures, the greatest proportional differences in relative frequency were seen for tube shunt procedures (2.55-fold higher in the AS), iStent and Hydrus procedures (2.52-fold higher in the NAS), and endoscopic cyclophotocoagulation (5.80-fold higher in the NAS).

CONCLUSIONS

Based on IRIS® Registry data, notable differences appear to exist with regard to ethno-racial groups, glaucoma severity, and diagnostic and surgical practice patterns in AS versus NAS. By understanding these differences, potential opportunities exist in the development of educational programs related to clinical and surgical glaucoma care.

Evaluation of the Cirrus High-Definition OCT Normative Database Probability Codes in a Black American Population

PURPOSE

Race-adjusted interpretation of data from Cirrus high-definition OCT (HD-OCT) devices is not standard practice. The aim of this study is to evaluate differences in peripapillary retinal nerve fiber layer (RNFL) thickness between healthy Black Americans and the Cirrus HD-OCT normative database.

DESIGN

This is a cross-sectional observational study using control patients recruited from the greater Philadelphia, Pennsylvania, area.

PARTICIPANTS

A total of 466 eyes were included in this study. Subjects were retrospectively identified from the control cohort of the Primary Open-Angle African American Glaucoma Genetics (POAAGG) study.

METHODS

Using an age-stratified or linear regression method, we reclassified white-green-yellow-red color probability codes for RNFL thicknesses by quadrant.

MAIN OUTCOME MEASURES

The distribution of reclassified color codes was compared with the expected 5%-90%-4%-1% percentiles and to the original color codes by the Cirrus machine.

RESULTS

Average RNFL thickness in the POAAGG control cohort was thinner than in the Cirrus normative database in all except the nasal quadrant. The original color codes of the POAAGG cohort did not fall into the expected distributions, with more RNFL measurements assigned as white and red codes than expected (9.5% and 1.7%) and fewer measurements assigned as green and yellow codes than expected (85.3% and 3.5%) (P < 0.001). Compared with the original Cirrus machine, reclassification using linear regression produced color codes closest to the expected distributions (P = 0.09). The proportion of abnormal results shifted closer to the expected 5% in the nasal (1.3%, P < 0.001 vs. 3.0%, P = 0.048) and temporal (8.2%, P = 0.002 vs. 3.6%, P = 0.18) quadrants.

CONCLUSIONS

Results further establish the presence of structural differences in the RNFL of Black American patients. Color code reclassification suggests that the existing Cirrus database may not be accurately evaluating glaucomatous nerves in patients of African descent. This study addresses an unmet need to assess Cirrus HD-OCT color probability codes in a Black American population.

Comparison of the Automated Pattern-Noise (PANO) Glaucoma Test with the HFA, an FDT Stimulus, and the Fundus Area Cup-to-disk Ratio

AIM AND OBJECTIVE

To compare the results of a new automated glaucoma test-Pattern-Noise (PANO)-to the Humphrey Visual Field Analyzer-II (HFA), the fundus area cup-to-disk ratio (CDR), and a frequency doubling technology (FDT) stimulus.

MATERIALS AND METHODS

This was a prospective study performed in the West-Region of Cameroon. Two hundred and nineteen eyes of 122 adult patients were included with a clinical suspicion of normal-tension or primary open-angle glaucoma and no other major ocular pathology. Eyes were examined with PANO, HFA (24-2 SITA standard), and FDT-stimulus in a randomized order followed by clinical assessment of the CDR.

RESULTS

Parametric correlation of the mean contrast threshold of PANO with the mean contrast threshold of FDT-stimulus, total deviation of HFA, and area CDR was 0.94, -0.85, and 0.62, respectively (p < 0.001 for all values). Spatial distribution of sensitivity thresholds is highly correlated (p < 0.001) at all points in the visual field between PANO and HFA. With cut-off values of 3 ± 1 dB for HFA mean deviation and 4 ± 1 for PANO mean contrast threshold and after eliminating borderline cases, PANO's sensitivity was 95% and specificity 60%. The mean patient age was 45.2 ± 15.8 years. Mean thresholds of PANO and FDT-stimulus decreased with increasing age. Mean examination time was 7.1 ± 1.8 minutes for PANO, 5.9 ± 1.3 minutes for HFA, and 4.7 ± 1.3 minutes for FDT-stimulus. The mean percentage of false-positives per examination was 4.95% for PANO, 4.62% (p = 0.025) for FDT-stimulus, and 2.10% for HFA.

CONCLUSION

The results showed that PANO was successful in suspecting the presence of glaucoma. Pattern-Noise examination led to findings that were significantly correlated to HFA, FDT stimulus, and area CDR. Some patterns of defect were also correlated. Furthermore, PANO showed a reasonable examination time and error rate.

CLINICAL SIGNIFICANCE

Affordable and robust visual field devices are lacking in large parts of the developing world. Comparing them to established methods is a prerequisite to their clinical use.

HOW TO CITE THIS ARTICLE

Hannen T, El-Khoury S, Patel R, et al. Comparison of the Automated Pattern-Noise (PANO) Glaucoma Test with the HFA, an FDT Stimulus, and the Fundus Area Cup-to-disk Ratio. J Curr Glaucoma Pract 2021;15(3):132-138.

Visual field defects due to optic nerve drusen in Afro-Caribbean patients: A case series of 16 eyes

INTRODUCTION

Optic Nerve Head Drusen (ONHD) are very rare among black patients but may cause more severe visual defects in these patients. The goal of our study was to describe the frequency of visual field defects secondary to OND in Afro-Caribbean patients and study the characteristics of their physical examination, color vision and contrast sensitivity.

METHODS

We carried out a prospective study at the Martinique university medical center on patients of African descent with ONHD diagnosed on fundus examination and B-scan ultrasonography. All patients received a complete neuro-ophthalmological examination. The primary study endpoint was the frequency of visual field defects. Secondary study endpoints were the results of ETDRS visual acuity, Pelli-Robson contrast sensitivity chart, and 15 hue color vision test.

RESULTS

Sixteen eyes of 10 patients from 11 to 68 years of age were included. Forteen eyes (87%) had exposed ONHD. Eleven eyes (69%) showed a visual field defect: 9 eyes (69%) had an enlarged blind spot, and 9 eyes (69%) had an arcuate scotoma. 3 eyes (19%) had loss of ETDRS visual acuity, and 12 eyes (75%) showed loss of Pelli-Robson contrast sensitivity. Five eyes (31%) had an abnormal color vision test.

CONCLUSION

This is one of the largest case series of ONHD in Black patients. The frequency of visual field defects was high but comparable to that of studies in other ethnic groups. Larger comparative studies are necessary to confirm these results.

Optic disc morphometry using spectral domain optical coherence tomography in a Nigerian population

PURPOSE

To assess morphological optic disc dimensions using spectral-domain optical coherence tomography (OCT) in a Nigerian population.

MATERIALS AND METHOD

Good quality SD-OCT scans of the optic disc of 147 eyes of 88 participants were selected, enrolled, and retrospectively reviewed. All subjects had optic nerve head and retinal nerve fibre layer OCT imaging, as well as analysis, done using the Topcon 3D OCT-1 Maestro®. The age, sex, and some OCT-generated optic disc dimensions namely disc area (DA), vertical disc diameter (VDD), horizontal disc diameter (HDD) were retrieved from the database and analyzed.

RESULTS

The mean age of the study subjects was 52.6±20.9 years with a range of 8-90 years; male to female ratio was 1:1.3. The right eye and left eye accounted for 75 and 72 of the 147 scans respectively. The mean DA, VDD, and HDD were 2.54 ± 0.48 mm2, 1926.5 ± 189.6 μm and 1673.9 ± 173.9 μm, respectively. Males had significantly larger DA than females (2.56 ± 0.53 mm2 vs 2.51 ± 0.44 mm2, p = 0.043). The mean DA and VDD of eyes of subjects aged 21-40 years were significantly higher compared to subjects aged 60 years and more (p = 0.008 and 0.001, respectively).

CONCLUSION

The mean optic disc area and diameters are larger than those reported in similar studies involving blacks and other races. The mean disc area reduces with increasing age.

Comparative Study of Lamina Cribrosa Thickness Between Primary Angle-Closure and Primary Open-Angle Glaucoma

Purpose

To compare lamina cribrosa thickness (LCT) of primary angle-closure glaucoma (PACG) and primary open-angle glaucoma (POAG) using the enhanced depth-imaging mode of the Heidelberg Spectralis spectral-domain optical coherence tomography (EDI-OCT).

Patients and Methods

A comparative cross-sectional study was conducted. We enrolled 34 patients with PACG, 38 with POAG, and 62 controls, testing only one eye of each participant. Lamina cribrosa thickness was determined at the center of the optic nerve head using EDI-OCT. Nine points of LCT were measured, and LCT averages were analyzed.

Results

Mean age, number of glaucoma medications, current intraocular pressure (IOP), cup to disc ratio, and visual field indices, were not significantly different between PACG and POAG eyes. The maximum IOP (SD) was higher in PACG than in POAG, at 32.5 (10.46) vs 25.05 (6.42) mmHg (p = 0.001), and LCTs were significantly different among the PACG, POAG and control groups. Mean (SD) LCTs were 226.99 (31.08), 257.17 (19.46), and 290.75 (28.02) μm, respectively (p < 0.001). Lamina cribrosa thickness was correlated with mean deviation of the visual field (p = 0.001; correlation coefficient, r_s = 0.347), while it was inversely correlated with maximum IOP (p < 0.001; correlation coefficient, r_s = −0.592). Linear regression analysis revealed that LCT was inversely related to age (p = 0.008), female (p = 0.018), and maximum IOP (p = 0.002). LCT was marginally related to visual field MD (p = 0.053).

Conclusion

Glaucomatous eyes had thinner LCT than controls, and maximum IOP was inversely correlated to the LCT. PACG eyes had higher maximum IOP and thinner LCT than POAG ones. In living eye, EDI-OCT emphasizes the pressure-dependent mechanism of glaucoma on lamina cribrosa deformation and the higher IOP-loaded stress which leads to a greater lamina cribrosa strain.

Optic nerve head anatomy in myopia and glaucoma, including parapapillary zones alpha, beta, gamma and delta: Histology and clinical features

The optic nerve head can morphologically be differentiated into the optic disc with the lamina cribrosa as its basis, and the parapapillary region with zones alpha (irregular pigmentation due to irregularities of the retinal pigment epithelium (RPE) and peripheral location), beta zone (complete RPE loss while Bruch's membrane (BM) is present), gamma zone (absence of BM), and delta zone (elongated and thinned peripapillary scleral flange) within gamma zone and located at the peripapillary ring. Alpha zone is present in almost all eyes. Beta zone is associated with glaucoma and may develop due to a IOP rise-dependent parapapillary up-piling of RPE. Gamma zone may develop due to a shift of the non-enlarged BM opening (BMO) in moderate myopia, while in highly myopic eyes, the BMO enlarges and a circular gamma zone and delta zone develop. The ophthalmoscopic shape and size of the optic disc is markedly influenced by a myopic shift of BMO, usually into the temporal direction, leading to a BM overhanging into the intrapapillary compartment at the nasal disc border, a secondary lack of BM in the temporal parapapillary region (leading to gamma zone in non-highly myopic eyes), and an ocular optic nerve canal running obliquely from centrally posteriorly to nasally anteriorly. In highly myopic eyes (cut-off for high myopia at approximately -8 diopters or an axial length of 26.5 mm), the optic disc area enlarges, the lamina cribrosa thus enlarges in area and decreases in thickness, and the BMO increases, leading to a circular gamma zone and delta zone in highly myopic eyes.

Retinal Nerve Fiber Layer Thickness in Healthy Eyes of Black, Chinese, and Latino Americans: A Population-Based Multiethnic Study

PURPOSE

To compare peripapillary retinal nerve fiber layer (RNFL) thickness among healthy adults by race and ethnicity and to identify determinants of RNFL thickness.

DESIGN

Population-based cross-sectional study.

PARTICIPANTS

Data from 6133 individuals (11 585 eyes) from 3 population-based studies in Los Angeles County, California, 50 years of age or older and of self-described African, Chinese, or Latin American ancestry.

METHODS

We measured RNFL thickness and optic nerve head parameters using the Cirrus HD-OCT 4000. Multivariate linear mixed regression was used to evaluate factors associated with RNFL thickness among participants without ocular diseases.

MAIN OUTCOME MEASURES

Determinants and modifiers of RNFL thickness.

RESULTS

The mean age of the participants was 60.1 years (standard deviation, 7.4 years). Black Americans showed the lowest RNFL thickness and smallest cup-to-disc ratio (CDR), and Chinese Americans showed the largest CDR and disc area after adjusting for age and gender (all P < 0.05). Per each 10-year older age group, the average RNFL thickness was 2.5 μm (95% confidence interval [CI], 1.8-3.1 μm), 2.8 μm (95% CI, 2.3-3.3 μm), and 3.5 μm (95% CI, 2.9-4.1 μm) thinner for Black, Chinese, and Latino Americans, respectively (age trend P < 0.05 and interaction P = 0.041). Black Americans compared with Chinese Americans, older age, male gender, hypertension, diabetes, greater axial length (AL), bigger disc area, and lower scan signal strength were associated with thinner average RNFL. Race, age, AL, disc area, and scan signal strength consistently were associated with RNFL thickness in all quadrants, whereas gender, hypertension, and diabetes were associated with RNFL thickness in select quadrants. Age and race explained the greatest proportion of variance of RNFL thickness.

CONCLUSIONS

Clinically important differences in RNFL thickness are present in healthy adults 50 years of age or older from different racial and ethnic groups of the same age, with the thinnest measures observed in Black Americans. This difference remains after accounting for disc size and AL. Furthermore, age-related RNFL thinning differs by race and ethnicity. Longitudinal studies are needed to verify our findings and to assess the influence of race and ethnicity in the clinical application of RNFL thickness.

Biomechanical research into lamina cribrosa in glaucoma

Glaucoma, a leading cause of irreversible blindness, poses a considerable public health challenge and burden. Mechanical models of the lamina cribrosa under elevated intraocular pressure at different scales, contributing significantly to uncovering the glaucomatous pathogenesis, are discussed. Meanwhile, the open issues and avenues for further development are highlighted.

Prevalence and Clinical Characteristics of Childhood Glaucoma at a Tertiary Care Children's Hospital

PRECIS

Glaucoma suspect was the most prevalent category in this study followed by glaucoma associated with acquired ocular anomaly and juvenile open-angle glaucoma. Primary congenital glaucoma was diagnosed in only 3% of the population studied.

PURPOSE

To describe the prevalence and clinical characteristics of childhood glaucoma diagnosed over a 10-year period among patients aged 18 years or below who were seen at a tertiary care children's hospital using the new Childhood Glaucoma Research Network classification system.

METHODS

Medical records of all patients aged 18 years or below (n=108) who were diagnosed with glaucoma between January 1, 2008 through September 30, 2018 were reviewed. Data collected included demographics (age at diagnosis, sex, and family history of glaucoma), intraocular pressure, disc-to-cup ratio, retinal nerve fiber layer thickness, and refractive errors. Clinical characteristics of each patient were evaluated according to the criteria established by Childhood Glaucoma Research Network. Categorical distributional equivalence comparisons were performed using the Pearson χ test. A P-value <0.05 was defined as statistically significant.

RESULTS

A total of 108 patients with a diagnosis of childhood glaucoma or glaucoma suspect were included in this study. Sixty-four percent of these patients were males (P<0.0001). The mean age at the time of diagnosis was 7.07±5.4 years. "Glaucoma suspect" was the most prevalent category (46%, P=0.0002), followed by glaucoma associated with the acquired ocular anomaly (20%) and juvenile open-angle glaucoma (16%). Primary congenital glaucoma represented 3% and all these patients were males. Sixty-nine percent of the patients had bilateral involvement (P=0.0073). The highest intraocular pressure recorded in the study was 57 mm Hg, the largest cup-to-disc ratio was 0.96, and the lowest retinal nerve fiber layer measurement was 39 μm. Ninety-two percent of the patients had refractive errors and 85% of them had astigmatism.

CONCLUSIONS

Establishing a pattern and the associated clinical characteristics of childhood glaucoma at tertiary care children's hospitals will help in developing collaborative research efforts and effective treatment/management strategies for children with these rare groups of disorders.

Effects of Study Population, Labeling and Training on Glaucoma Detection Using Deep Learning Algorithms

Purpose

To compare performance of independently developed deep learning algorithms for detecting glaucoma from fundus photographs and to evaluate strategies for incorporating new data into models.

Methods

Two fundus photograph datasets from the Diagnostic Innovations in Glaucoma Study/African Descent and Glaucoma Evaluation Study and Matsue Red Cross Hospital were used to independently develop deep learning algorithms for detection of glaucoma at the University of California, San Diego, and the University of Tokyo. We compared three versions of the University of California, San Diego, and University of Tokyo models: original (no retraining), sequential (retraining only on new data), and combined (training on combined data). Independent datasets were used to test the algorithms.

Results

The original University of California, San Diego and University of Tokyo models performed similarly (area under the receiver operating characteristic curve = 0.96 and 0.97, respectively) for detection of glaucoma in the Matsue Red Cross Hospital dataset, but not the Diagnostic Innovations in Glaucoma Study/African Descent and Glaucoma Evaluation Study data (0.79 and 0.92; P < .001), respectively. Model performance was higher when classifying moderate-to-severe compared with mild disease (area under the receiver operating characteristic curve = 0.98 and 0.91; P < .001), respectively. Models trained with the combined strategy generally had better performance across all datasets than the original strategy.

Conclusions

Deep learning glaucoma detection can achieve high accuracy across diverse datasets with appropriate training strategies. Because model performance was influenced by the severity of disease, labeling, training strategies, and population characteristics, reporting accuracy stratified by relevant covariates is important for cross study comparisons.

Translational Relevance

High sensitivity and specificity of deep learning algorithms for moderate-to-severe glaucoma across diverse populations suggest a role for artificial intelligence in the detection of glaucoma in primary care.

[Evaluation of mean macular thickness by optical coherence tomography (SD OCT) in black Senegalese subjects]

INTRODUCTION

Our goal was to evaluate the normal macular thickness in Blacks by OCT and to determine socio-demographic and clinical parameters which may influence it.

MATERIALS AND METHODS

This was a multicenter, prospective, descriptive study over 6 months. It included Black adults followed in the ophthalmology departments of Abass Ndao and Aristide-Le-Dantec hospitals in Dakar. Included subjects had corrected visual acuity of 10/10 (0 logMAR) and P2 (+0.1 logMAR), clear ocular media, and no retinal abnormalities. We used the Topcon 3D 2000 OCT to measure the central thicknesses of the cornea (CT) and of the macula (MT), and cup to disc ratio (C/D) in each eye. Socio-demographic, clinical and tomographic data were collected on a survey form and correlated to the MT. The analysis was carried out by the Epi info 7 software. We used the Chi² comparison test with a P value˂0.05.

RESULTS

One hundred and nine patients were included. The mean age was 27.39 years with a male/female ratio of 0.65. The subjects were emmetropic in 54.13% of cases. The mean CT was 519.97μm, the mean C/D was 0.23, and the mean MT was 264.35μm. The P-value (P) was greater than or equal to 0.1 for all the factors studied.

CONCLUSION

MT in our study was lower than that of Whites, and the various parameters studied did not demonstrate a statistically significant influence on MT.

The African Descent and Glaucoma Evaluation Study (ADAGES) III: Contribution of Genotype to Glaucoma Phenotype in African Americans: Study Design and Baseline Data

PURPOSE

To describe the study protocol and baseline characteristics of the African Descent and Glaucoma Evaluation Study (ADAGES) III.

DESIGN

Cross-sectional, case-control study.

PARTICIPANTS

Three thousand two hundred sixty-six glaucoma patients and control participants without glaucoma of African or European descent were recruited from 5 study centers in different regions of the United States.

METHODS

Individuals of African descent (AD) and European descent (ED) with primary open-angle glaucoma (POAG) and control participants completed a detailed demographic and medical history interview. Standardized height, weight, and blood pressure measurements were obtained. Saliva and blood samples to provide serum, plasma, DNA, and RNA were collected for standardized processing. Visual fields, stereoscopic disc photographs, and details of the ophthalmic examination were obtained and transferred to the University of California, San Diego, Data Coordinating Center for standardized processing and quality review.

MAIN OUTCOME MEASURES

Participant gender, age, race, body mass index, blood pressure, history of smoking and alcohol use in POAG patients and control participants were described. Ophthalmic measures included intraocular pressure, visual field mean deviation, central corneal thickness, glaucoma medication use, or past glaucoma surgery. Ocular conditions, including diabetic retinopathy, age-related macular degeneration, and past cataract surgery, were recorded.

RESULTS

The 3266 ADAGES III study participants in this report include 2146 AD POAG patients, 695 ED POAG patients, 198 AD control participants, and 227 ED control participants. The AD POAG patients and control participants were significantly younger (both, 67.4 years) than ED POAG patients and control participants (73.4 and 70.2 years, respectively). After adjusting for age, AD POAG patients had different phenotypic characteristics compared with ED POAG patients, including higher intraocular pressure, worse visual acuity and visual field mean deviation, and thinner corneas (all P < 0.001). Family history of glaucoma did not differ between AD and ED POAG patients.

CONCLUSIONS

With its large sample size, extensive specimen collection, and deep phenotyping of AD and ED glaucoma patients and control participants from different regions in the United States, the ADAGES III genomics study will address gaps in our knowledge of the genetics of POAG in this high-risk population.

Optic Disc Measurements with the 78 Diopter Lens, Zeiss 4-Mirror Contact Lens and Computerized Image Analysing System

We evaluated the 78 diopter (D) lens and Zeiss 4-mirror lens for the measurement of vertical and horizontal optic disc diameters during slit-lamp biomicroscopy and compared the results with the measurements made with the computerized image analysing system (IMAGEnet 640, Topcon, Japan) in 30 eyes of 30 patients. The 78D lens and Zeiss 4-mirror lens measurements both correlated well with the computerized image analysis measurements (r=0.881 for vertical and r=0.895 for horizontal disc diameter measurements with the 78D lens and r=0.883 for vertical and r=0.891 for horizontal disc diameter measurements with the Zeiss 4-mirror lens). The 78D lens measurements overestimated vertical disc diameter by 5.3% and horizontal disc diameter by 4.4%. The Zeiss 4-mirror lens underestimated the vertical disc diameter by 2.4% and horizontal disc diameter by 2.2%. Thus either lens can be used for a quick estimation of the optic disc size, since the results correlate well with the computerized image analysis measurements.

A Small Disc Area Is a Risk Factor for Visual Field Loss Progression in Primary Open-Angle Glaucoma: The Glaucoma Stereo Analysis Study

Purpose

The Glaucoma Stereo Analysis Study, a cross-sectional multicenter collaborative study, used a stereo fundus camera (nonmyd WX) to assess various morphological parameters of the optic nerve head (ONH) in glaucoma patients. We compared the associations of each parameter between the visual field loss progression group and no-progression group.

Methods

The study included 187 eyes of 187 patients with primary open-angle glaucoma or normal-tension glaucoma. We divided the mean deviation (MD) slope values of all patients into the progression group (<−0.3 dB/year) and no-progression group (≧−0.3 dB/year). ONH morphological parameters were calculated with prototype analysis software. The correlations between glaucomatous visual field progression and patient characteristics or each ONH parameter were analyzed with Spearman's rank correlation coefficient.

Results

The MD slope averages in the progression group and no-progression group were −0.58 ± 0.28 dB/year and 0.05 ± 0.26 dB/year, respectively. Among disc parameters, vertical disc width (diameter), disc area, cup area, and cup volume in the progression group were significantly less than those in the no-progression group. Logistic regression analysis revealed a significant association between the visual field progression and disc area (odds ratio 0.49/mm² disc area).

Conclusion

A smaller disc area may be associated with more rapid glaucomatous visual field progression.

Variation in the Three-Dimensional Histomorphometry of the Normal Human Optic Nerve Head With Age and Race: Lamina Cribrosa and Peripapillary Scleral Thickness and Position

Purpose

This study quantified the thickness and depth of the lamina cribrosa (LC) and peripapillary scleral thickness in high-resolution three-dimensional (3D) fluorescent reconstructions of the optic nerve head (ONH) in eyes from donors of African (AD) and European descent (ED).

Methods

A total of 64 eyes (45 ED, 19 AD) from 51 normal donors were obtained within 6 hours of death and fixed at 10 mm Hg of pressure. The optic nerve head was trephined from the globe and digitally reconstructed at 1.5 × 1.5 × 1.5 μm voxel resolution with an automated episcopic fluorescence technique. The load-bearing ONH connective tissue surfaces were manually delineated in 3D using custom software.

Results

The lamina cribrosa and peripapillary sclera were significantly thinner in AD eyes adjusting for age and sex (LC was 24 ± 11 μm thinner; P = 0.0350; scleral was 56 ± 22 μm thinner; P = 0.0097). The lamina cribrosa was significantly thinner in females (23 ± 11 μm thinner; P = 0.0425). Age was not significantly associated with any morphologic parameter in the ED group. However, increasing age was associated with an increase in scleral thickness (1.3 μm/year, P = 0.0499) and an increase in LC depth (2.3 μm/year, P = 0.0035) in the AD group. The sclera was thickest in the superior and temporal regions while the LC was thinnest superiorly.

Conclusions

Substantial sectorial and racial differences in LC and scleral morphology were observed, as well as increasing LC depth and scleral thickness with age in the AD group. Results suggest greater age-related remodeling of the load-bearing ONH connective tissues in eyes from AD individuals that could explain, in part, the greater predilection to glaucomatous injury seen in aged AD populations.

Study on the deformations of the lamina cribrosa during glaucoma

The lamina cribrosa is the primary site of optic nerve injury during glaucoma, and its deformations induced by elevated intraocular pressure are associated directly with the optic nerve injury and visual field defect. However, the deformations in a living body have been poorly understood yet so far. It is because that integral observation and precise measurement of the deformations in vivo are now almost impossible in the clinical diagnosis and treatment of glaucoma. In the present study, a new mechanical model of the lamina cribrosa is presented by using Reissner's thin plate theory. This model accurately displays the stress and deformation states in the lamina cribrosa under elevated intraocular pressure, in which the shear deformation is not presented by the previous models, however, is demonstrated to play a key role in the optic nerve injury. Further, the deformations of the structures, involving the optic nerve channels and the laminar sheets in the lamina cribrosa, are first investigated in detail. For example, the dislocation of the laminar sheets reaches 18.6μm under the intraocular pressure of 40mmHg, which is large enough to damage the optic nerve axons. The results here confirm some previously proposed clinical speculations on the deformations of the pore shape in the lamina cribrosa under elevated intraocular pressure during glaucoma. Finally, some essentially clinical questions existed during glaucoma, such as the pathological mechanism of the open-angle glaucoma with normal intraocular pressure, are discussed. The present study is beneficial to deeply understanding the optic nerve injury during glaucoma.

STATEMENT OF SIGNIFICANCE

The lamina cribrosa is the primary site of the optic nerve injury induced by elevated intraocular pressure during glaucoma. Under high intraocular pressure, the optic nerve channel near to the periphery of the lamina cribrosa (Channel A) is deformed to become into a tortuous elliptical horn from a straight cylinder, while the optic nerve channel near to the center of the lamina cribrosa (Channel B) is deformed to become into a straight horn from a straight cylinder. These deformations cause both the axoplasm flow obstacle in the axon fibers and the blocked blood flow in the capillaries which pass through the channels, and trigger the visual field defect during glaucoma.

Comparison of Bruch's Membrane Opening Minimum Rim Width Among Those With Normal Ocular Health by Race

PURPOSE

To examine if racial differences in Bruch's membrane opening minimum rim width (BMO-MRW) in spectral-domain optical coherence tomography (SDOCT) exist, specifically between people of African descent (AD) and European descent (ED) in normal ocular health.

DESIGN

Cross-sectional study.

METHODS

Patients presenting for a comprehensive eye examination at retail-based primary eye clinics were enrolled based on ≥1 of the following at-risk criteria for glaucoma: AD aged ≥40 years, ED aged ≥50 years, diabetes, family history of glaucoma, and/or pre-existing diagnosis of glaucoma. Participants with normal optic nerves on examination received SDOCT of the optic nerve head (24 radial scans). Global and regional (temporal, superotemporal, inferotemporal, nasal, superonasal, and inferonasal) BMO-MRW were measured and compared by race using generalized estimating equations. Models were adjusted for age, sex, and BMO area.

RESULTS

SDOCT scans from 269 eyes (148 participants) were included in the analysis. Mean global BMO-MRW declined as age increased. After adjusting for age, sex, and BMO area, there was not a statistically significant difference in mean global BMO-MRW by race (P = .60). Regionally, the mean BMO-MRW was lower in the crude model among AD eyes in the temporal, superotemporal, and nasal regions and higher in the inferotemporal, superonasal, and inferonasal regions. However, in the adjusted model, these differences were not statistically significant.

CONCLUSIONS

BMO-MRW was not statistically different between those of AD and ED. Race-specific normative data may not be necessary for the deployment of BMO-MRW in AD patients.

Risk Factors for Non-arteritic Anterior Ischaemic Optic Neuropathy in a Korean Population

To determine the risk factors for non-arteritic anterior ischaemic optic neuropathy (NAION) in Korean patients, medical records from 45 Korean patients group and 45 healthy controls group were retrospectively reviewed. 10 NAION risk factors, including age, sex, associated systemic disease, past medical/social history, and fundus findings were analyzed. Significant risk factors for NAION in Korean patients were diabetes mellitus (odds ratio (OR) = 3.613, p = 0.020), hypercholesterolaemia (OR = 5.200, p = 0.001), smoking (OR = 3.58, p = 0.014), microaneurysm/haemorrhage (OR = 5.375, p = 0.024), and crowded small cup (OR = 17.200, p < 0.001).

A retrospective survey of childhood glaucoma prevalence according to Childhood Glaucoma Research Network classification

Purpose:

To evaluate the Childhood Glaucoma Research Network (CGRN) classification system and describe the prevalence of each subtype according to this classification.

Materials and Methods:

Retrospectively, the medical records of 205 consecutive childhood glaucoma and glaucoma suspect patients at an urban tertiary care center were reviewed. The initial diagnosis and new diagnosis according to CGRN classification were recorded.

Results:

All patients fit one of the seven categories of the new classification. Seventy-one percent of diagnoses were changed upon reclassification. Twenty-three percent of patients had primary glaucoma (juvenile open-angle glaucoma and primary congenital glaucoma [PCG]); 36% had secondary glaucoma (glaucoma associated with nonacquired ocular anomalies; glaucoma associated with nonacquired systemic disease or syndrome; glaucoma associated with acquired condition; and glaucoma following cataract surgery); and 39% were glaucoma suspect. Of the patients diagnosed with glaucoma, PCG was the most common diagnosis, seen in 32% of patients.

Conclusion:

The CGRN classification provides a useful method of classifying childhood glaucoma.

Optic Nerve Head Drusen Prevalence and Associated Factors in Clinically Normal Subjects Measured Using Optical Coherence Tomography

OBJECTIVE

To investigate the prevalence of optic nerve head drusen (ONHD) in clinically normal subjects using enhanced depth imaging (EDI) optical coherence tomography (OCT) and to evaluate associated factors.

DESIGN

Prospective, cross-sectional, observational study.

PARTICIPANTS

Total of 130 clinically normal subjects.

METHODS

Serial horizontal and vertical EDI OCT B-scans (interval between scans, ∼30 μm) of the optic nerve head (ONH) were obtained in both eyes of clinically normal subjects. Signs of ONHD were defined as horizontal hyperreflective bands perpendicular to the OCT beam with or without a signal-poor core. The minimum length of isolated hyperreflective bands was determined based on analysis of 34 eyes with clinically definite ONHD. Age, gender, ONH diameter, and axial length were obtained from participants.

MAIN OUTCOME MEASURES

Prevalence of ONHD in clinically normal subjects and its association with age, gender, ONH diameter, and axial length.

RESULTS

Based on the measurements of 94 isolated hyperreflective bands in the 34 eyes with clinically definite ONHD, the minimum length of isolated hyperreflective ONHD bands in clinically normal subjects was set as 45 μm (mean minus 2 standard deviations). Among 260 clinically normal eyes (130 subjects; 68 women; mean age, 40±17 years), EDI OCT was positive for horizontal hyperreflective ONHD bands in 28 eyes (10.8%) of 19 subjects (14.6%). Of these 28 eyes, 25 eyes (9.6% of total 260 eyes) of 16 subjects (12.3% of total 130 subjects) showed isolated hyperreflective bands with no signal-poor core, and 3 eyes (1.2% of total 260 eyes) of 3 subjects (2.3% of total 130 subjects) showed a signal-poor core surrounded by hyperreflective bands. No significant differences were found in mean age (44 vs. 39 years; P = 0.121) or gender distribution (56% vs. 52% female; P = 0.766) between clinically normal subjects with hyperreflective ONHD bands and those without. Logistic regression analysis showed that a decrease in ONH diameter by 100 μm and axial length by 1 mm increased the odds of ONHD presence by 1.5-fold (odds ratio [OR] = 1.56 [confidence interval (CI), 1.22-2.00]; P < 0.001) and 2-fold (OR = 2.00 [CI, 1.15-3.49]; P = 0.015), respectively.

CONCLUSIONS

Subclinical ONHD may be more prevalent than previously believed. Significant associations of subclinical ONHD with smaller ONH and shorter axial length were found.

Influence of Myopia on Size of Optic Nerve Head and Retinal Nerve Fiber Layer Thickness Measured by Spectral Domain Optical Coherence Tomography

Purpose

To investigate optic nerve head size and retinal nerve fiber layer (RNFL) thickness according to refractive status and axial length.

Methods

In a cross-sectional study, 252 eyes of 252 healthy volunteers underwent ocular biometry measurement as well as optic nerve head and RNFL imaging by spectral-domain optical coherence tomography. Correlation and linear regression analyses were performed for all subjects. The magnification effect was adjusted by the modified axial length method.

Results

Disc area and spherical equivalent were positively correlated (r = 0.225, r² = 0.051, p = 0.000). RNFL thickness showed significant correlations with spherical equivalent (r = 0.359, r² = 0.129, p = 0.000), axial length (r = -0.262, r² = 0.069, p = 0.000), disc radius (r = 0.359, r² = 0.129, p = 0.000), and radius of the scan circle (r = -0.262, r² = 0.069, p = 0.000). After adjustment for the magnification effect, those relationships were reversed; RNFL thickness showed negative correlation with spherical equivalent and disc radius, and positive correlation with axial length and radius of the scan circle. The distance between the disc margin and the scan circle was closely correlated with RNFL thickness (r = -0.359, r² = 0.129, p = 0.000), which showed a negative correlation with axial length (r = -0.262, r² = 0.069, p = 0.000).

Conclusions

Optic disc radius and RNFL thickness decreased in more severely myopic eyes, but they increased after adjustment for magnification effect. The error due to the magnification effect and optic nerve head size difference might be factors that should be considered when interpreting optical coherence tomography results.

Optic nerve head topography and retinal structural changes in eyes with macrodisks: a comparative study with spectral domain optical coherence tomography

Purpose

To compare optic nerve head parameters, the thicknesses of the peripapillary retinal nerve fiber layer (pRNFL), the macular retinal nerve fiber layer (mRNFL), the ganglion cell complex (GCC), and the ganglion cell–inner plexiform layer (GCIPL) in macrodisks and normal-sized healthy disks using spectral domain optical coherence tomography.

Patients and methods

A total of 88 healthy eyes (42 macrodisks and 46 normal-sized disks) were prospectively enrolled in the study. Optic nerve head parameters as well as pRNFL, mRNFL, GCC, and GCIPL thicknesses were measured in all subjects. Optic disk areas (ODAs) >2.70 mm² were defined as macrodisks. All spectral domain optical coherence tomography parameters were compared between normal-sized disks and macrodisks.

Results

The mean age of the participants was 49.4±5.7 years in the normal size group and 51.55±6.3 years in the macrodisk group (P=0.65). The average ODAs were 2.23±0.29 mm² and 3.30±0.59 mm² in the normal size and the macrodisk groups, respectively. ODA (P<0.001), cup area (P<0.001), cup disk area ratio (P<0.001), horizontal cup disk ratio (P<0.001), vertical cup disk ratio (P<0.001), horizontal disk diameter (P<0.001), vertical disk diameter (P<0.001), and cup volume (P<0.001) were significantly higher in the macrodisk group. The inferior mRNFL thickness was significantly lower (P=0.042), and the GCC inferior and GCIPL inferior thicknesses were found to be lower with low significance (P=0.052, P=0.059, respectively) in the macrodisk group. Rim volume (P=0.622), total pRNFL (P=0.201), superior pRNFL (P=0.123), inferior pRNFL (P=0.168), average macular thickness (P=0.162), total mRNFL (P=0.171), superior mRNFL (P=0.356), total GCC (P=0.080), superior GCC (P=0.261), total GCIPL (P=0.214), and superior GCIPL (P=0.515) thicknesses were similar in both groups.

Conclusion

Optic disk topography and retinal structures show different characteristics in healthy eyes with macrodisks. These disk size-dependent variations suggest that large optic disks may be more susceptible to glaucomatous damage.

Primary Open-Angle Glaucoma in Individuals of African Descent: A Review of Risk Factors

OBJECTIVE

To identify the major risk factors for primary open-angle glaucoma (POAG) in individuals of African descent.

METHODS

We searched PubMed for relevant articles, with results spanning April 1947 to present. All abstracts were reviewed and, where relevant to POAG and race, articles were catalogued and analyzed. Additional sources were identified through citations in articles returned by our search.

RESULTS

Numerous potential POAG risk factors were identified and organized into categories by demographics (age, sex, and skin color), lifestyle choices (smoking, alcohol), comorbidities (hypertension, diabetes, and obesity), ophthalmic findings (eye structure, central corneal thickness, corneal hysteresis, elevated intraocular pressure, myopia, cataract, and vascular abnormalities), family history, socioeconomic status, and adherence. Older age, male sex, lower central corneal thickness, decreased corneal hysteresis, elevated intraocular pressure, myopia, vascular abnormalities, and positive family history were definitively associated with increased risk of POAG.

CONCLUSIONS

Individuals at greatest risk for POAG should be screened by an ophthalmologist to allow earlier detection and to slow disease progression. Further studies on the genetics of the disease will provide more insight into underlying pathologic mechanisms and could lead to improved therapeutic interventions. Continued research in urban areas with large populations of blacks is especially needed.

HRT for the Diagnosis and Detection of Glaucoma Progression

Confocal scanning laser ophthalmoscopy through the Heidelberg Retina Tomograph (HRT) provides a rapid, safe, noncontact, and noninvasive imaging of the optic disc in three-dimensions, and provides precise detailed information about the optic disc beyond that which the clinical exam can measure. The HRT I was developed for research purposes only and was not used clinically. The HRT II was developed to be user-friendly, more rapid, and was used as an adjunct to clinical examination in the detection and progression of glaucoma. One of the main pitfalls of the HRT II was that it was operator-dependent. The HRT III was developed to be operator-independent. Initially the Moorsfield Regression Analysis provided the analysis of the stereometric optic disc parameters. The Glaucoma Probability Score, given its ease of use, operator-independence, and rapidity of use, soon gained popularity. Numerous studies have compared these two methods of analysis, with the conclusion that the Glaucoma Probability Score provides a higher sensitivity and a lower specificity than the Moorsfield Regression Analysis, which may indicate that it has potential as a screening test for glaucoma. However, there is no consensus on the use of the Glaucoma Probability Score as a screening test for glaucoma. While HRT data may be useful as a clinical adjunct in the screening and diagnosis of glaucoma, it should ultimately only be used to support clinical examination.

Differences in ocular blood flow in glaucoma between patients of African and European descent

PURPOSE

To investigate differences in ocular blood flow in individuals of African descent (AD) and European descent (ED) with open angle glaucoma (OAG).

PATIENTS AND METHODS

A retrospective data analysis was performed on OAG patients of AD and ED who were previously examined for ocular blood flow within the Department of Ophthalmology at Indiana University School of Medicine. Data analysis included blood pressure, heart rate, visual fields, intraocular pressure, ocular perfusion pressure, and color Doppler imaging of retrobulbar vessels. Color Doppler imaging measurements were performed on ophthalmic, central retinal, and nasal and temporal short posterior ciliary arteries, with peak systolic (PSV) and end diastolic velocities (EDV) as well as the Pourcelot vascular resistive index calculated for each vessel. Two-sample t tests of unequal variance were performed with P values <0.05 considered statistically significant.

RESULTS

OAG patients of AD had statistically significant lower retrobulbar blood flow values than patients of ED including lower ophthalmic artery PSV (P=0.0001), ophthalmic artery EDV (P=0.0008), central retinal artery PSV (P=0.01), temporal short posterior ciliary artery PSV (P=0.0037), and nasal short posterior ciliary artery PSV (P<0.0001). No significant differences were found in terms of intraocular pressure or visual field parameters.

CONCLUSIONS

Significantly lower blood flow values were identified in all retrobulbar blood vessels in AD compared with ED OAG patients. These findings suggest that the contribution of ocular blood flow to the disease process may be different in AD compared with ED OAG patients.

Variation of laminar depth in normal eyes with age and race

PURPOSE

To determine if laminar depth (LD) and prelaminar tissue volume (PTV) are associated with age and race in healthy human eyes.

METHODS

Optic nerve head images from enhanced depth imaging spectral-domain optical coherence tomography of 166 normal eyes from 84 subjects of African descent (AD) and European descent (ED) were manually delineated to identify the principal surfaces: internal limiting membrane, Bruch's membrane (BM), anterior sclera (AS), and anterior surface of the lamina cribrosa. These four surfaces defined the LD and PTV using Bruch's membrane opening (BMO) and AS for reference structures. Generalized estimating equations were used to evaluate whether the effect of age on each outcome was differential by race.

RESULTS

When age was analyzed as a continuous variable, the interaction term between age and race was statistically significant for mean LDBMO (P = 0.015) and mean LDAS (P = 0.0062) after adjusting for axial length and BMO area. For every 1-year increase in age, the LDAS was greater on average by 1.78 μm in AD subjects and less by 1.71 μm in ED subjects. Mean PTV was lower in the older subjects (1248 × 10(6) μm(3) AD, 881 × 10(6) μm(3) ED) compared to the younger subjects (1316 × 10(6) μm(3) AD, 1102 × 10(6) μm(3) ED) in both groups.

CONCLUSIONS

With increasing age, the LD changes differently across racial groups in normal subjects. The LD in ED subjects showed a significantly decreasing slope suggesting that the lamina moves anteriorly with age in this group.

Vascular considerations in glaucoma patients of African and European descent

Glaucoma is the leading cause of blindness in individuals of African descent (AD). While open-angle glaucoma (OAG) disproportionately affects individuals of AD compared with persons of European descent (ED), the physiological mechanisms behind this disparity are largely unknown. The more rapid progression and greater severity of the disease in persons of AD further raise the concern for identifying these underlying differences in disease pathophysiology between AD and ED glaucoma patients. Ocular structural differences between AD and ED patients, including larger optic disc area, cup:disc ratio and thinner corneas, have been found. AD individuals are also disproportionately affected by systemic vascular diseases, including hypertension, cardiovascular disease, stroke and diabetes mellitus. Abnormal ocular blood flow has been implicated as a risk factor for glaucoma, and pilot research is beginning to identify localized ocular vascular differences between AD and ED OAG patients. Given the known systemic vascular deficits and the relationship between glaucoma and ocular blood flow, exploring these concepts in terms of glaucoma risk factors may have a significant impact in elucidating the mechanisms behind the disease disparity in the AD population.

Ethnic variation in optic disc size by fundus photography

PURPOSE

To compare optic disc size among Caucasian, Chinese, African, Filipino and Hispanic subjects recruited from a university-based general ophthalmology clinic.

METHODS

In this retrospective cross-sectional study, optic disc size was calculated from fundus photographs. Differences in age, sex and spherical equivalent among the ethnic groups were examined with either Kruskal--Wallis test or Chi-square test. Ethnic differences in optic disc size were evaluated with linear mixed-effects regression models that adjusted for age, sex, spherical equivalent, glaucoma status, lens status and use of both eyes in the same subject.

RESULTS

Five hundred and seventy-four eyes of 305 subjects were analyzed. The mean and standard deviation of the optic disc size were 2.16 ± 0.41 mm(2) for Caucasian, 2.30 ± 0.56 mm(2) for Chinese, 2.31 ± 0.41 mm(2) for Filipino, 2.38 ± 0.40 mm(2) for African and 2.40 ± 0.38 mm(2) for Hispanic subjects. Age and spherical equivalent differed among the ethnic groups by Kruskal--Wallis test (p < 0.05). Sex differed among the ethnic groups by Chi-square test (p < 0.05). Ethnic differences in optic disc size were not observed among African, Hispanic, Filipino and Chinese subjects in linear mixed-effects regression analyses (p > 0.05). However, Caucasian differed from the other ethnicities in linear mixed-effects regression analyses (p < 0.05).

CONCLUSIONS

Optic disc size was significantly smaller in Caucasian compared to the other ethnic groups. Optic disc size differences among non-Caucasian ethnic groups were not significant.

Optic disc size and progression of visual field damage in patients with normal-tension glaucoma

Purpose

Our goal was to evaluate the influence of optic disc size on the progression of visual field damage in patients with normal-tension glaucoma (NTG).

Subjects and methods

Eighty-two eyes of 82 NTG patients who had been receiving topical antiglaucoma medications and followed-up for more than 4 years were enrolled in this study. The patients were allocated to two groups, according to the mean size of their optic discs. The data were analyzed using regression analysis, based on the Cox proportional hazard model.

Results

The probability of visual field stability was significantly lower in eyes with large discs than in those with small discs (log rank test, P = 0.007). Progression of visual field damage was significantly associated with the optic disc area (hazard ratio [HR]: 1.812, P = 0.018), occurrence of disc hemorrhage (HR: 2.116, P = 0.028), and intraocular pressure reduction ratio (HR: 0.957, P = 0.014).

Conclusion

The optic disc area correlates with progression of visual field damage in patients with NTG.

The Pathogenesis of Nonarteritic Anterior Ischemic Optic Neuropathy

Although nonarteritic anterior ischemic optic neuropathy (NAION) is known to occur as a result of ischemic insult to the anterior portion of the optic nerve, its etiology and pathogenesis remain elusive. Because NAION is a nonfatal condition, acute, postmortem histopathologic analysis has never been undertaken. Animal models of NAION have been created with the use of an iodinated derivative of fluorescein, rose bengal. When rose bengal is stimulated with the use of a frequency-doubled neodymium-Yttrium aluminium garnet (YAG) laser diode, vascular endothelial damage may be induced in a precise and focal manner, within the anterior optic nerve. Primate and nonprimate animal models of NAION differ from the human pattern of NAION in the duration of the disease course, as well as the anatomy. The rat lamina cribrosa contains a differing connective tissue structure, which may result in a differing pathogenesis of ischemic insult. Optic disk swelling resolves within 5 days in rats and 14 days in primates; in humans, it is known to persist for up to 6 weeks. Animal models have nonetheless enabled a deeper understanding of the underlying pathologic processes in NAION.

CDKN2B-AS1 genotype-glaucoma feature correlations in primary open-angle glaucoma patients from the United States

PURPOSE

To assess the association between single nucleotide polymorphisms (SNPs) of the gene region containing cyclin-dependent kinase inhibitor 2B antisense noncoding RNA (CDKN2B-AS1) and glaucoma features among primary open-angle glaucoma (POAG) patients.

DESIGN

Retrospective observational case series.

METHODS

We studied associations between 10 CDKN2B-AS1 SNPs and glaucoma features among 976 POAG cases from the Glaucoma Genes and Environment (GLAUGEN) study and 1971 cases from the National Eye Institute Glaucoma Human Genetics Collaboration (NEIGHBOR) consortium. For each patient, we chose the feature from the eye with the higher value. We created cohort-specific multivariable models for glaucoma features and then meta-analyzed the results.

RESULTS

For 9 of the 10 protective CDKN2B-AS1 SNPs with minor alleles associated with reduced disease risk (eg, the G allele at rs2157719), POAG patients carrying these minor alleles had smaller cup-to-disc ratio (0.05 units smaller per G allele at diagnosis; 95% CI: -0.08, -0.03; P = 6.23E-05) despite having higher intraocular pressure (IOP) (0.70 mm Hg higher per G allele at DNA collection; 95% CI: 0.40, 1.00; P = 5.45E-06). For the 1 adverse rs3217992 SNP with minor allele A associated with increased disease risk, POAG patients with A alleles had larger cup-to-disc ratio (0.05 units larger per A allele at diagnosis; 95% CI: 0.02, 0.07; P = 4.74E-04) despite having lower IOP (-0.57 mm Hg per A allele at DNA collection; 95% CI: -0.84, -0.29; P = 6.55E-05).

CONCLUSION

Alleles of CDKN2B-AS1 SNPs, which influence risk of developing POAG, also modulate optic nerve degeneration among POAG patients, underscoring the role of CDKN2B-AS1 in POAG.

Effect of optic disc size and disease severity on the diagnostic capability of glaucoma imaging technologies in an Indian population

PURPOSE

To evaluate the influence of optic disc size and disease severity on the diagnostic validity of optical coherence tomography (Stratus OCT), scanning laser polarimetry [GDx variable corneal compensator (VCC)], and confocal scanning laser ophthalmoscopy [Heidelberg retina tomograph II (HRT II)] in Indian eyes with glaucoma.

METHODS

Ninety-five normal and 125 glaucoma patients underwent imaging with Stratus OCT, GDx VCC, and HRT II. One eye of each person was randomly selected for analysis. Using disc area determined on HRT II, discs were classified as small (<2 mm), moderate (2 to 3 mm), and large (>3 mm). The parameter with the best sensitivity for each device, at a fixed specificity, was compared for different disc sizes. Logistic marginal regression was used to study the effect of disc size and disease severity (mean deviation on standard automated perimetry) on the diagnostic performance of these imaging devices.

RESULTS

At a fixed specificity of 84.2%, the sensitivity of HRT II was significantly different for varying disc sizes (P=0.0004). The sensitivities for dissimilar disc sizes were not significantly different for the GDx VCC (P=0.928) or Stratus OCT (P=0.381). Logistic marginal regression also showed that sensitivity of HRT II increased with increasing disc size, whereas sensitivity of OCT and GDx were independent of the disc size. The sensitivity of all 3 technologies increased with increasing disease severity (decreasing mean deviation).

CONCLUSIONS

Optic disc size affects the diagnostic capability of HRT II but not that of GDx VCC or Stratus OCT. The sensitivity of all 3 imaging technologies increased with increasing disease severity.

Optic nerve head drusen in black patients

BACKGROUND

Several studies have suggested racial differences in the prevalence of optic nerve head drusen (ONHD). We aimed to determine the percentage of patients with ONHD who are black and to describe the clinical, ophthalmoscopic, and perimetric findings in these patients.

METHODS

We conducted a retrospective chart review of all patients with ONHD seen at our institution between 1989 and 2010. Only black patients with ONHD confirmed on either funduscopy or B-scan ultrasonography were included. Demographic and clinical findings in these patients were recorded and analyzed.

RESULTS

Of the 196 patients with confirmed ONHD, 10 (5.1%) were black. This included 7 females and 3 males with ages ranging from 8 to 61 years. Six of the 10 patients had bilateral ONHD. The ONHD were buried in 11 of 16 eyes and exposed in 5 of 16 eyes. Fifteen of 16 eyes with ONHD had small cupless optic nerve heads. Visual fields were normal in 4 of 16 eyes with ONHD. In the remainder, visual field defects included an enlarged blind spot (5 eyes), constricted field (5 eyes), nasal defect (2 eyes), central defect (1 eye), and generalized depression (1 eye). Visual field defects were present in 4 of 5 eyes (80%) with exposed ONHD and 8 of 11 eyes (72.7%) with buried ONHD. None of the patients were related, and none of their examined family members had exposed ONHD on funduscopic examination.

CONCLUSIONS

ONHD are rare in blacks, possibly due to the presence of a larger cup-to-disc ratio or a lack of predisposing genetic factors. Visual field defects are common in black patients with both exposed and buried ONHD.

Glaucomatous optic nerve head alterations in patients with chronic heart failure

Purpose

To evaluate the association between chronic heart failure (CHF) and optic nerve head alterations.

Methods

A cross-sectional study was performed. Heart failure patients with recent echocardiograms were subjected to ophthalmologic examinations, including intraocular pressure measurement, optic nerve head, and retinal nerve fiber layer evaluation using stereophotography, Heidelberg retinal tomography, and standard automated perimetry. The ocular findings were correlated with the cardiological evaluation, and compared with a control group without cardiopathy.

Results

A total of 30 patients with CHF and 30 individuals without cardiopathy were enrolled in this study. The mean (standard deviation [SD]) intraocular pressure was 12.3 (2.5) mmHg in the CHF group, and 14.7 (2.9) mmHg in the control group (P < 0.001). The mean (SD) arterial blood pressure was 86.9 (17.1) mmHg in the CHF group, and 103.6 (15.2) mmHg in the control group (P < 0.001). The mean (SD) ocular perfusion pressure was 45.6 (11.1) mmHg in the CHF group, and 54.4 (10.4) mmHg in the control group (P = 0.001). The mean (SD) rim area was 1.41 (0.3) mm² in the CHF group, and 1.60 (0.26) mm² in the control group (P = 0.003). The mean (SD) vertical cup/disc ratio was 0.51 (0.17) in the CHF group, and 0.41 (0.18) in the control group (P = 0.02). The Moorfields regression analysis was outside the normal limits in 16 out of 58 (27.6%) eyes of the CHF subjects, and in 4 out of 60 (6.7%) eyes of the control subjects (P = 0.01). The frequency of glaucoma was 10% in the CHF group, whereas none of the control subjects met the criteria for the diagnosis of glaucoma (P = 0.24).

Conclusion

CHF is associated with lower ocular perfusion pressure, and glaucomatous optic nerve head changes.

Corneal refractive power and its associations with ocular and general parameters: the Central India Eye and Medical Study

PURPOSE

To investigate the normal distribution of corneal refractive power (CRP) and its associations with other ocular and systemic parameters in the Central Indian population.

DESIGN

Population-based study.

PARTICIPANTS

The Central India Eye and Medical Study is a population-based study performed in a rural region of Central India. The study comprised 4711 subjects aged 30+ years.

METHODS

A detailed ophthalmic and medical examination was performed. Horizontal and vertical CRP were measured using a non-automatic keratometer.

MAIN OUTCOME MEASURES

Corneal refractive power.

RESULTS

After excluding pseudophakic or aphakic eyes, keratometric measurements were available on 9024 eyes of 4617 study participants (98.0%) with a mean age of 49.1±13.2 years (range, 30-100 years) and a mean refractive error of -0.20±1.52 diopters (D). Mean horizontal CRP was 44.60±1.68 D (mean ± standard deviation; range, 36.5-52.0 D), and vertical CRP was 44.62±1.74 D (range, 37.75-52.0 D) with no significant difference between both parameters (P=0.27). In multivariate analysis, CRP was significantly (P < 0.001) associated with the systemic parameters of increasing age (P < 0.001), lower level of education (P=0.02), and lower body height (P < 0.001), and with the ocular parameters of thinner central corneal thickness (P < 0.001), deeper anterior chamber (P < 0.001), shorter axial length (P < 0.001), and myopic refractive error (P < 0.001). The results remained unchanged if eyes with CRP ≥48 D were excluded.

CONCLUSIONS

Horizontal CRP increased with higher age, lower level of education, lower body height, thinner central cornea, deeper anterior chamber, shorter axial length, and myopic refractive error. The association with age may be of importance for refractive surgery. The association of a steeper cornea with a shorter body stature and a shorter axial length parallels an association between shorter body length and shorter axial length without association with refractive error. The association among steeper cornea, shorter body length, and lower educational level complements the association between shorter body length and lower educational level. The correlation between steeper cornea and deeper anterior chamber may be explained geometrically.