Oct signal of macular photoreceptors remains altered despite successful macular hole surgery

Abstract

Abstract: : Purpose: to assess the characteristics of the photoreceptor line on OCT scans and detect their changes after macular hole closure. As already shown by others with a ultrahigh–resolution OCT prototype (Drexler W, Arch Ophthalmol 2003;121:695), Stratus OCT ( Carl Zeiss Dublin USA), is indeed able to show a hyper–reflective line above the retinal pigment epithelium (RPE), which is thought to be generated by photoreceptor (PR) components. Methods: The macula of 10 normal eyes and 10 eyes successfully operated on for macular hole was examined by OCT. The reflectivity of the PR line was assessed in the two groups of patients, and. for this reflectivity in the central part of the macula were compared in these groups. All the measurements were made on 6 mm horizontal scans passing through the macular center. The PR layer was detected as the first hyperreflective line, lying just above the RPE. The characteristics of this line were measured using the OCT Stratus A–scan profile program. The intensity of PR and RPE line reflectivity (in decibels, dB) , was measured at the peak corresponding to these lines. The measures were made at the central point, and at every pixel on each side up to 5 pixels (30 µm). Additional measures were made every 5 pixels up to 210 µm from the center on each side. The Wilcoxon test was used to compare the values of the two groups. Results: in the normal eyes the PR line was hyper–reflective and continous, with no single pixel of less than 30 dB. In the central 60 µm the mean reflectivity of the PR line was 50.80 dB ± 4.9, and was separated from the RPE line from 46.6 ± 9 µm. The overall reflectivity of the PR line in the central 420 µm was 53.34dB. The RPE reflectivity was 63.74 dB. In the eyes with a closed macular hole, the PR line was broken at or next its center. In the 66 µm central area, the mean reflectivity was 43.11dB , i.e. significantly less than in normal eyes (p=0.01) , although theRPE reflectivity RPE was 65.03dB , which is not different from normal eyes (p=0.4). Conclusions: Stratus OCT allows the detection of a hyper–reflective line above the RPE which corresponds to the PR signal. In eyes with a surgically closed macular hole, the PR line was broken or fairly discontinuous and altered at the center despite tissue closure at the foveola.

Keywords: retina • macular holes • photoreceptors