Investigating Macular Tissue Integrity Index as a Novel Biomarker in Geographic Atrophy

Area of Science:

• Ophthalmology
• Retinal Diseases
• Clinical Trials

Background:

• Geographic atrophy (GA) enlargement is a common clinical trial outcome.
• Current metrics may lack specificity for central macular involvement and structure-function relationships.
• A targeted approach is needed to monitor GA progression in the central macula.

Purpose of the Study:

• To evaluate the correlation between retinal tissue and photoreceptor integrity within central macular zones (1-mm and 3-mm) and visual function.
• To assess the utility of novel biomarkers, Macular Tissue Integrity Index (MTII) and EZ Integrity Index (EZII), in monitoring GA.
• To determine the benefit of including GA expansion beyond the 3-mm perifoveal zone in visual function analysis.

Main Methods:

• Retrospective, longitudinal analysis of a GA clinical trial cohort (43 eyes).
• Quantified MTII and EZII using fundus autofluorescence and OCT scans at baseline and 1 year.
• Assessed correlations between MTII, EZII, overall GA area, and visual acuity (BCVA, LLVA).

Main Results:

• MTII and EZII within the central 1-mm zone significantly correlated with best-corrected visual acuity (BCVA).
• EZII in the 3-mm zone correlated with both BCVA and low-luminance visual acuity (LLVA).
• Changes in MTII or EZII were not associated with overall GA area growth.

Conclusions:

• MTII and EZII are novel biomarkers for macular photoreceptor integrity.
• These indices show distinct correlations with visual acuity based on the measurement zone.
• Findings support MTII and EZII utility in assessing macular integrity and highlight GA progression heterogeneity.