Spatial Cluster Patterns of Retinal Sensitivity Loss in Intermediate Age-Related Macular Degeneration Features

Standard automated perimetry for glaucoma and diseases of the retina and visual pathways: Current and future perspectives

Static automated perimetry (SAP) remains a mainstay of functional assessment of the visual field in diseases of the visual pathway, such as glaucoma and age-related macular degeneration. The fundamental psychophysical task of responding to stimuli of different levels of contrast has remained minimally changed since its inception in the 1980s, and this is potentially the root of several unresolved issues involving the technique. Enduring issues include the optimisation of SAP parameters for maximising defect detection, the influence of subjective behaviour on the response, structure-function discordance, and ageing- and disease-related changes of the visual pathway. Addressing these issues has been a focus of our research program and is the subject of this manuscript. We will review some of the basic psychophysical principles and methods that have contributed to the development of SAP and their contributions to its output measurements. Parameters that are interrogated include stimulus size and background luminance and their modification to improve defect defection in glaucoma and age-related macular degeneration. We propose frameworks for optimising testing parameters and leveraging the results for changing clinical care. In our pursuit of optimising the structure-function relationship in the eye, several areas of research have been developed and explored, including: the reconciliation of subjective responses in perimetry; by minimising sources of biases, such as Method of Limits we have been able to equate static and kinetic perimetry outputs in relation to underlying structural loci. This also formed the basis for our clustering framework, which groups together statistically similar structural and functional test locations to maximise structure-function concordance. Throughout the manuscript, we review the scientific underpinnings of clinical measurements, framing application into real-world patients to improve clinical practice.

Retinal Pigment Epithelium Curvature Can Predict Late Age-Related Macular Degeneration

Purpose

Outer retinal band integrity strongly predicts late age-related macular degeneration (AMD). However, it is often assessed subjectively as "continuity" using inconsistent definitions. Alternatively, "curvature" of the outer retinal bands is a quantitative metric that strongly correlates with AMD biomarkers and can screen for intermediate AMD. We evaluated the prognostic ability of retinal pigment epithelium (RPE) and ellipsoid zone (EZ) curvature for late AMD against outer retinal band continuity, pigmentary abnormalities, reticular pseudodrusen, and drusen volume.

Methods

Consecutive patients with intermediate AMD who progressed to late AMD (n = 17) or remained stable (n = 42) were recruited. RPE and EZ curvature were quantified as a ratio of their lengths over Bruch's membrane using the sinuosity method of assessing river curvature, where a ratio of ∼1 indicates no outer retinal pathology. RPE, EZ, and Bruch's membrane were manually segmented and their lengths automatically extracted. The primary outcomes were outer retinal sinuosity and the odds ratio of predicting late AMD.

Results

Mean follow-up time for progressors and nonprogressors was 4.4 and 3.6 years. RPE sinuosity was strongly associated with pigmentary abnormalities (P = 0.001) and drusen volume (P = 0.004) but not reticular pseudodrusen (P = 0.28). RPE sinuosity >1.03 was the strongest predictor of late AMD developing within 5 years (15 [2.9-75]) and across the study period (25 [2.3-282]). Drusen volume >0.03 mm3 was the strongest predictor of progression within 2 years (33 [2.5-426]), and RPD could not independently predict progression within any time frame.

Conclusions

RPE curvature is a promising, quantitative outer retinal biomarker that can prognosticate late AMD and potentially enhance prognostic models.

Retinal sensitivity changes in early/intermediate AMD: a systematic review and meta-analysis of visual field testing under mesopic and scotopic lighting

Visual fields under mesopic and scotopic lighting are increasingly being used for macular functional assessment. This review evaluates its statistical significance and clinical relevance, and the optimal testing protocol for early/intermediate age-related macular degeneration (AMD). PubMed and Embase were searched from inception to 14/05/2022. All quality assessments were performed according to GRADE guidelines. The primary outcome was global mean sensitivity (MS), further meta-analysed by: AMD classification scheme, device, test pattern, mesopic/scotopic lighting, stimuli size/chromaticity, pupil dilation, testing radius (area), background luminance, adaptation time, AMD severity, reticular pseudodrusen presence, and follow-up visit. From 1489 studies screened, 42 observational study results contributed to the primary meta-analysis. Supported by moderate GRADE certainty of the evidence, global MS was significantly reduced across all devices under mesopic and scotopic lighting with large effect size (-0.9 [-1.04, -0.75] Hedge's g, P < 0.0001). The device (P < 0.01) and lighting (P < 0.05) used were the only modifiable factors affecting global MS, whereby the mesopic MP-1 and MAIA produced the largest effect sizes and exceeded test-retest variabilities. Global MS was significantly affected by AMD severity (intermediate versus early AMD; -0.58 [-0.88, -0.29] Hedge's g or -2.55 [3.62, -1.47] MAIA-dB) and at follow-up visit (versus baseline; -0.62 [-0.84, -0.41] Hedge's g or -1.61[-2.69, -0.54] MAIA-dB). Magnitudes of retinal sensitivity changes in early/intermediate AMD are clinically relevant for the MP-1 and MAIA devices under mesopic lighting within the central 10° radius. Other factors including pupil dilation and dark adaptation did not significantly affect global MS in early/intermediate AMD.

Spatial Analysis Reveals Vascular Changes in Retinal and Choroidal Vessel Perfusion in Intermediate AMD With Reticular Pseudodrusen

Purpose

To examine the effect of reticular pseudodrusen (RPD) on retinal and choroidal vessel perfusion (VP) topography in intermediate age-related macular degeneration (iAMD) using refined spatial analyses.

Methods

This was a retrospective cross-sectional study of 120 individuals with 30 iAMDRPD, 60 iAMDno_RPD, and 30 normal eyes, propensity-score matched by age, sex, and presence of cardiovascular-related disease. VP of the superficial and deep retinal and choriocapillaris vascular slabs was assessed from 6 × 6-mm optical coherence tomography angiography (OCTA) scans divided into 126 × 126 grids, with adjustment for various person- and eye-level factors. Grid-wise VP differences (%) among the groups were spatially assessed according to analyses based on the Early Treatment for Diabetic Retinopathy Study (ETDRS), eccentricity (µm), and degree (°).

Results

VP was significantly decreased between iAMDRPD and iAMDno_RPD, across all vascular slabs in various ETDRS sectors (up to -2.16%; 95% confidence interval, -2.99 to -1.34; P < 0.05). Eccentricity analyses revealed more complex patterns: a bisegmented relationship where VP in iAMDRPD eyes decreased linearly toward 1000 µm then returned toward similar values as iAMDno_RPD, plateauing around 2000 µm in the superficial and 3000 µm in the deep retina (R2 = 0.57-0.9; P < 0.001). Degree-based analysis further showed that the greatest VP differences in iAMDRPD eyes were commonly located superiorly and nasally across all vascular slabs (P < 0.05).

Conclusions

RPD appears to compound the vascular impact of iAMD, displaying complex spatial patterns beyond the ETDRS sectors. This highlights the importance of considering spatial delineations for future work regarding the role of RPD and vascular dysfunction.