VISUAL FUNCTION CORRELATES OF FOVEAL SLOPE CHANGES ON OPTICAL COHERENCE TOMOGRAPHY IN MACULAR TELANGIECTASIA TYPE 2

To evaluate changes in foveal and parafoveal thickness measured using optical coherence tomography across five stages of macular telangiectasia 2 (MacTel 2) and to correlate the foveal slope angle with best-corrected visual acuity (BCVA).

A multicentered, cross-sectional study of 90 patients with bilateral MacTel 2 was carried out. We reviewed medical records of patients who had undergone optical coherence tomography. Mean retinal thickness foveal and subfoveal were noted from ETDRS (Early Treatment Diabetic Retinopathy Study) mapping and later used for calculating foveal slope angle. The change in retinal thickness and foveal angle across five stages of MacTel 2 was assessed. Central foveal thickness and foveal slope angle were correlated with BCVA.

The foveal slope angles were calculated quadrantwise and stagewise. The mean slope angle was minimum in temporal quadrant (6.29°) followed by inferior (7.13°), superior (7.54°), and nasal (7.93°). The slope angles were 9.27°, 7.95°, 6.70°, 6.10°, and 6.31° in Stages 1, 2, 3, 4, and 5, respectively. Statistically significant correlation noted between the temporal, superior, inferior slope angles and BCVA (in logarithm of the minimum angle of resolution) with r = -0.18, -0.19, and -0.25, respectively (P < 0.05). No statistically significant correlation was noted between central retinal thickness and BCVA.

The BCVA correlates better with slope angles than central retinal thickness. This implies that, change in both foveal and parafoveal regions accounts for vision change. Greater the foveal slope angle, the better the vision.