Functional relevance of macular telangiectasia (MacTel) area on multicolour imaging in type 2 MacTel

Purpose: To analyse the correlation between area of macular telangiectasia (MacTel) involvement on multicolour (MC) imaging, disease stages and visual acuity in type 2 MacTel. Methods: In this retrospective analysis of MC images, confirmed cases of type 2 MacTel were graded into different disease stages as per Gass and Blodi and Yannuzzi et al classification systems. The 'MacTel area' was calculated by marking the outer boundary of an area with abnormally increased reflectivity to confocal blue wavelength light. At every follow-up visit, best-corrected visual acuity, MacTel area and stage of disease on the MC image was documented. Analyses between disease stage, MacTel area and visual acuity was carried out. Results: In total, 92 eyes of 49 patients were included in the study. The mean age was 59.6 +/- 8.96 years. About 182 high-quality gradable MC images were available for analysis. There was a statistically significant difference in the visual acuity (p < 0.001) and area of involvement (p < 0.001) in the non-proliferative and proliferative type 2 MacTel groups. An increase in disease severity stage statistically correlated positively with Mactel area (r = 0.544; p < 0.001) and logMAR visual acuity (r = 0.329; p < 0.001). Over time, there was a significant increase in area of MacTel involvement (p = 0.012) with an associated decrease in the visual acuity (p = 0.023). Conclusion: The MacTel area measured on MC imaging showed a strong positive correlation with disease stage and a negative correlation with visual acuity. This could serve as a useful biomarker in clinical trials and understanding the natural history of the disease.