The In Vivo Correlation between Retinal Pigment Epithelium Thickness and Quantitative Fundus Autofluorescence in a White Population

Bruch's Membrane: A Key Consideration with Complement-Based Therapies for Age-Related Macular Degeneration

The complement system is crucial for immune surveillance, providing the body's first line of defence against pathogens. However, an imbalance in its regulators can lead to inappropriate overactivation, resulting in diseases such as age-related macular degeneration (AMD), a leading cause of irreversible blindness globally affecting around 200 million people. Complement activation in AMD is believed to begin in the choriocapillaris, but it also plays a critical role in the subretinal and retinal pigment epithelium (RPE) spaces. Bruch's membrane (BrM) acts as a barrier between the retina/RPE and choroid, hindering complement protein diffusion. This impediment increases with age and AMD, leading to compartmentalisation of complement activation. In this review, we comprehensively examine the structure and function of BrM, including its age-related changes visible through in vivo imaging, and the consequences of complement dysfunction on AMD pathogenesis. We also explore the potential and limitations of various delivery routes (systemic, intravitreal, subretinal, and suprachoroidal) for safe and effective delivery of conventional and gene therapy-based complement inhibitors to treat AMD. Further research is needed to understand the diffusion of complement proteins across BrM and optimise therapeutic delivery to the retina.

Quantitative autofluorescence findings in patients undergoing hydroxychloroquine treatment

Background

Methods

Results

Conclusions

Quantitative Fundus Autofluorescence in the Developing and Maturing Healthy Eye

Purpose

Quantitative fundus autofluorescence (QAF) enables comparisons of autofluorescence intensities among participants. While clinical QAF reports mostly focused on the healthy and diseased adult retina, only very limited data of QAF in the maturing eye are available. Here, we report QAF in a large cohort of healthy children.

Methods

In this prospective monocentric cross-sectional study, 70 healthy Caucasian children (5–18 years) were multimodal imaged, including QAF and spectral domain optical coherence tomography. QAF and retinal thicknesses were measured at predefined locations (along horizontal meridian; Early Treatment Diabetic Retinopathy Study [ETDRS] grid) and correlated using custom written Fiji plugins. Standard retinae for different age groups were generated.

Results

Fifty-three participants were included. QAF was low in childhood but increased steadily (P < 0.001), also at the fovea (P < 0.001), with no gender differences (P = 0.61). The QAF distribution was similar to adults showing highest values superior-temporally. At individual points, retinal thickness remained stable, while using the ETDRS pattern, the retinal pigment epithelium (RPE) thickness increased significantly with aging. Standard QAF retinae of age groups also showed an increase with aging.

Conclusions

QAF can be reliably performed in young children. Function–structure correlation showed a thickening of the RPE and an increasing QAF with aging, probably related to the histologic low number of RPE autofluorescent granules at a younger age but further deposition of these granules during maturation. Standard retinae help to distinguish abnormal QAF in the diseased retina of age-matched patients.

Translational Relevance

Our data bridge the gap between preclinical QAF and clinical data application and structural OCT correlation in children.

The effect of COVID-19 pandemic restrictions on neovascular AMD patients treated with treat-and-extend protocol

Purpose

To investigate the adherence rate of neovascular age-related macular degeneration (nAMD) patients in treat-and-extend (TAE) protocol to their anti-vascular endothelial growth factor (anti-VEGF) intravitreal injection (IVI) appointments and to evaluate the functional and anatomical outcomes of the patients who attended and did not attend their IVI appointments during the coronavirus disease 2019 (COVID-19) restriction period (RP).

Methods

The patients with nAMD having IVI appointments between March 16 and June 1, 2020 (RP in Turkey) were included in this retrospective study. For adherence analysis, the patients who attended (Group 1, n = 44) and who did not attend (Group 2, n = 60) their IVI appointment visits during the RP (V_RP) were evaluated according to their last visit before the RP (V₀). For outcome analysis, the patients who attend V_RP and have follow-up (Group 1a, 46 eyes) and who did not attend V_RP but later attended for follow-up (Group 2a, 33 eyes) were evaluated for functional (best-corrected visual acuity, BCVA [logMAR]) and anatomical (optical coherence tomography [OCT] disease activity) outcomes at the first visit after RP (V₁) and last visit within six months after RP (V₂). Patients received a complete ophthalmologic evaluation with anti-VEGF (Aflibercept) IVI administration at all visits.

Results

The adherence rate of the patients to V_RP was 42.3% (44/104). The patients in Group 1 were significantly younger (mean ± SD years, 71.0 ± 8.1 vs. 74.7 ± 8.0, p = 0.024), had better median [IQR] BCVA at their first presentation (0.30 [0.54] vs. 0.61 [1.08], p = 0.023) and V₀ (0.40 [0.48] vs. 0.52 [0.70], p = 0.031), and had less hypertension (36.4% vs. 58.3%, p = 0.044) than Group 2. The mean ± SD delay of planned IVI at V_RP in Group 2a was 13.9 ± 6.2 weeks. Disease activity in OCT was significantly higher in Group 2a than Group 1a at V₁ (60.6% vs. 32.6%, p = 0.025). In Group 2a, the median (IQR) BCVA was significantly worse at V₁ (0.70 [0.58]) and V₂ (0.70 [0.59]) than V₀ (0.52 [0.40], p = 0.047 and p = 0.035, respectively).

Conclusions

More than half of the scheduled nAMD patients in TAE protocol missed their IVI visits during the RP, which resulted in a delay of their treatments. The delay of IVI treatment in those patients resulted in an increase in OCT disease activity and a decrease in BCVA.