To correlate macular thickness determined by optical coherence tomography (OCT) with light increment sensitivity and visual acuity in patients with type 2 idiopathic macular telangiectasia (IMT).

Prospective, cross-sectional study.

Fifty-one eyes of 30 patients with type 2 IMT were investigated. Functional assessment included best-corrected visual acuity and fundus-related microperimetry (MP1; Nidek Technologies, Padova, Italy). Retinal thickness was analyzed quantitatively by OCT3 (Carl Zeiss Meditec, Jena, Germany). The main outcome measure was the correlation of light sensitivity and visual acuity with retinal thickness.

Mean central retinal thickness was reduced compared with that of normal eyes. There was no significant correlation between central foveal thickness and foveal light sensitivity or visual acuity, respectively. Also, there was no significant correlation between mean retinal thickness temporal to the fovea and the lowest light sensitivity within that area. However, central light sensitivity in eyes with normal central foveal thickness was lower than in eyes with subnormal central foveal thickness (P = .032); this was also true for the lowest light sensitivity found temporal to the fovea (P = .025). Mean visual acuity was 20/40 and did not show significant differences in the two thickness groups.

A subnormal foveal thickness in type 2 IMT may be associated with better macular function as assessed by microperimetry. It is hypothesized that in type 2 IMT, both a primary neurosensory thinning and a low-grade macular edema can be involved. The coincidence may result in normal retinal thickness but decreased retinal function.