Thinning rates of retinal nerve layer and ganglion cell-inner plexiform layer in various stages of normal tension glaucoma

Comparison of Retinal Nerve Fiber Layer and Ganglion Cell Complex Rates of Change in Patients With Moderate to Advanced Glaucoma

PURPOSE

To compare ganglion cell complex (GCC) and retinal nerve fiber layer (RNFL) rates of change (RoC) in eyes with central or moderate to advanced glaucoma.

DESIGN

Prospective cohort study.

PARTICIPANTS

A total of 918 matched macular and RNFL OCT scan pairs from 109 eyes (109 patients) enrolled in the Advanced Glaucoma Progression Study with ≥2 years of follow-up and ≥4 OCT scans.

METHODS

We exported GCC and RNFL thickness measurements in 49 central macular superpixels and 12 RNFL clock-hour sectors, respectively. We applied our latest Bayesian hierarchical longitudinal model to estimate population and subject-specific baseline thickness (intercepts) and rates of change (RoC) in macular superpixels and RNFL sectors. Global RNFL and GCC RoC were analyzed in a single bivariate longitudinal model to properly compare them accounting for the correlation between their RoC.

MAIN OUTCOME MEASURES

Proportion of significant negative (deteriorating) and positive (improving) RoC expressed in μm/year. Standardized RoC were calculated by dividing RoC by the corresponding population SD. Analyses were repeated in eyes with visual field mean deviation (MD) ≤-6 and > -6 dB.

RESULTS

Average (SD) 24-2 visual field MD and follow-up length were -8.6 (6.3) dB and 4.2 (0.5) years, respectively. Global RNFL RoC (-0.70 µm/year) were faster than GCC (-0.44 µm/year) (P < .001); corresponding normalized RoC were not significantly different (P = .052). In bivariate analysis, patients with a significant negative global RNFL RoC (n = 63, 57%) or GCC (n = 56, 51%) frequently did so for both outcomes (n = 49, 45%). The average proportion of significantly decreasing RNFL sectors within an eye was 30.7% in eyes with MD > -6 dB compared to 20.5% in those with MD ≤ -6 dB (P = .014); the proportions for GCC superpixels were 21.1% versus 18.7%, respectively (P = .63).

CONCLUSIONS

Both GCC and RNFL measures can detect structural progression in glaucoma patients with central damage or moderate to advanced glaucoma. The clinical utility of RNFL imaging decreases with worsening severity of glaucoma.

Optic neuropathy in high myopia: Glaucoma or high myopia or both?

Due to the increasing prevalence of high myopia around the world, structural and functional damages to the optic nerve in high myopia has recently attracted much attention. Evidence has shown that high myopia is related to the development of glaucomatous or glaucoma-like optic neuropathy, and that both have many common features. These similarities often pose a diagnostic challenge that will affect the future management of glaucoma suspects in high myopia. In this review, we summarize similarities and differences in optic neuropathy arising from non-pathologic high myopia and glaucoma by considering their respective structural and functional characteristics on fundus photography, optical coherence tomography scanning, and visual field tests. These features may also help to distinguish the underlying mechanisms of the optic neuropathies and to determine management strategies for patients with high myopia and glaucoma.

Mendelian randomization analyses in ocular disease: a powerful approach to causal inference with human genetic data

Ophthalmic epidemiology is concerned with the prevalence, distribution and other factors relating to human eye disease. While observational studies cannot avoid confounding factors from interventions, human eye composition and structure are unique, thus, eye disease pathogenesis, which greatly impairs quality of life and visual health, remains to be fully explored. Notwithstanding, inheritance has had a vital role in ophthalmic disease. Mendelian randomization (MR) is an emerging method that uses genetic variations as instrumental variables (IVs) to avoid confounders and reverse causality issues; it reveals causal relationships between exposure and a range of eyes disorders. Thus far, many MR studies have identified potentially causal associations between lifestyles or biological exposures and eye diseases, thus providing opportunities for further mechanistic research, and interventional development. However, MR results/data must be interpreted based on comprehensive evidence, whereas MR applications in ophthalmic epidemiology have some limitations worth exploring. Here, we review key principles, assumptions and MR methods, summarise contemporary evidence from MR studies on eye disease and provide new ideas uncovering aetiology in ophthalmology.

Optical Microangiography and Progressive Ganglion Cell-Inner Plexiform Layer Loss in Primary Open-Angle Glaucoma

PURPOSE

To evaluate the association between optical microangiography (OMAG) measurements and progressive ganglion cell-inner plexiform layer (GCIPL) loss in patients with primary open-angle glaucoma (POAG).

DESIGN

Prospective case series.

METHODS

Sixty-three eyes of 38 patients with POAG were studied for ≥2 years and with ≥ 3 optical coherence tomography examinations. Only those hemifields with mild to moderate functional damage at baseline (106 hemifields) were included in the analysis. OMAG imaging was performed at the baseline visit. The effects of clinical parameters (age, gender, central corneal thickness, presence of disc hemorrhage, and mean and fluctuation of intraocular pressure), baseline mean deviation, retinal nerve fiber layer, and GCIPL thickness and baseline OMAG measurements (peripapillary and macular perfusion density [PD] and vessel density [VD]) on the rate of change of GCIPL thickness were evaluated using linear mixed models.

RESULTS

Average (± standard deviation) mean deviation, quadrant retinal nerve fiber layer, and sector GCIPL thickness of the analyzed hemifields respectively at baseline were -5.2 ± 2.8 dB, 94.5 ± 20.0 µm, and 72.4 ± 8.7 µm, respectively. Peripapillary PD and VD in the quadrant were 43.1% ± 7.0% and 17.0 ± 2.6 mm/mm², respectively. Macular PD and VD in the quadrant were 37.2% ± 6.9% and 15.1 ± 2.6 mm/mm², respectively. Rate of sector GCIPL change was -0.97 ± 0.15 µm per year. Multivariate mixed models showed that lower peripapillary PD (coefficient 0.04, P = .01) and VD (coefficient 0.09, P = .05) were significantly associated with a faster rate of GCIPL loss.

CONCLUSIONS

Lower baseline peripapillary OMAG measurements were significantly associated with a faster rate of GCIPL loss in patients with mild to moderate POAG.

Clinical Predictors of the Region of First Structural Progression in Early Normal-tension Glaucoma

PURPOSE

This study aimed to compare the clinical characteristics of patients who showed structural progression in the peripapillary retinal nerve fiber layer (RNFL) first against those who showed progression in the macular ganglion cell-inner plexiform layer (GCIPL) first and to investigate clinical parameters that help determine whether a patient exhibits RNFL or GCIPL damage first.

METHODS

A retrospective review of medical records of patients diagnosed with early-stage normal-tension glaucoma was performed. All eyes underwent intraocular pressure measurement with Goldmann applanation tonometer, standard automated perimetry, and Cirrus optical coherence tomography at 6-month intervals. Structural progression was determined using the Guided Progression Analysis software. Blood pressure was measured at each visit.

RESULTS

Forty-one eyes of 41 patients (mean age, 52.6 ± 16.7 years) were included in the study. In 21 eyes, structural progression was first detected in the RNFL at 54.2 ± 14.8 months, while structural progression was first observed at the macular GCIPL at 40.5 ± 11.0 months in 20 eyes. The mean intraocular pressure following treatment was 13.1 ± 1.8 mmHg for the RNFL progression first group and 13.4 ± 1.8 mmHg for the GCIPL progression first group (p = 0.514). The GCIPL progression first group was older (p = 0.008) and had thinner RNFL at baseline (p = 0.001). The logistic regression analyses indicated that both age and follow-up duration until first progression predicted the region of structural progression (odds ratio, 1.051; 95% confidence interval, 1.001-1.105; p = 0.046 for age; odds ratio, 0.912; 95% confidence interval, 0.840-0.991; p = 0.029 for time until progression).

CONCLUSIONS

Age of glaucoma patients and time until progression are associated with the region of the first structural progression in normal-tension glaucoma. Further studies exploring the association between glaucomatous progression and the location of damage are needed.