We evaluated the relationship between the delayed visual acuity (VA) improvement and retinal features, including in the photoreceptor layer, after a successful macular hole surgery using optical coherence tomography (OCT) images during long-term post-operative observation. The goal was to find the mechanism in delayed VA improvement.

Postoperative OCT scans were analyzed in nine eyes of eight patients who underwent idiopathic macular hole surgery between June 2003 to June 2005. Horizontal and vertical OCT scans taken of the operated eyes immediately after absorption of intraocular gas and after VA improvement were exported to Adobe Photoshop 7.0. We measured changes in parameters of the central foveal thickness (central 1 mm area), photoreceptor layer thickness, relative reflectivity of photoreceptor to retinal pigment epithelium, and the defective area of photoreceptor layer.

The median visual acuity was determined to be 0.2 (range: 0.15~0.3) at the VA unimproved period and 0.5 (range: 0.3~1.0) at VA improved period. The mean central foveal thickness decreased from 221.3 µm (range: 155~265 µm) to 191.2 µm (range: 150~231 µm), as VA improved ( p =0.007). The mean photoreceptor layer thickness increased from 15.2 µm (range: 4.2~27.6 µm) to 22.6 µm (range: 4.2~35.8 µm) as VA improved ( p =0.032), and mean relative reflectivity of photoreceptor layer increased from 0.43 (range: 0.08~0.67) to 0.48 (range: 0.10~0.70), as VA improved ( p =0.415). The defective area of photoreceptor layer decreased from 70% (range: 90~45%) to 27% (range: 8~5), as VA improved ( p =0.001).

A decrease of the central foveal thickness and of photoreceptor layer defective signal, and an increase of photoreceptor layer thickness were observed on OCT during delayed vision improvement after a successful macular hole surgery. Improvement of macular edema and photoreceptor reorganization are suggested as important parts of the mechanism toward vision recovery.