Abstract
Purpose: :
To investigate changes of the photoreceptor layer in tissue layer image using spectral domain optical coherence tomography (SD-OCT) after a successful macular hole (MH) surgery.
Methods: :
Twenty four eyes with MH which was closed surgically were studied prospectively. Visual acuity and SD-OCT scans using Cirrus HD-OCT® (Carl Zeiss) were obtained at baseline, 1, 2, 4 and 6 months after surgery. The scanned data were processed with embedded tools of the Advanced visualization to generate tissue layer image of the photoreceptor layer, namely photoreceptor layer map (PLM) which looks like fundus photograph. Hypo-reflective area and relative reflectivity at the fovea were measured and analyzed to find correlation with visual acuity.
Results: :
The mean visual acuity improved from 48.1 letters preoperatively to 62.5 letters at 1 month and to 73.8 letters at 6 months after the operation. Hypo-reflective area in PLM corresponded to attenuated or missing signal from the junction of the inner and outer segments of the photoreceptors (IS/OS) in the cross-sectional image. Before operation, mean area of hole base was 0.50mm2 and that of hypo-reflectivity was 3.44mm2. At 1 month, all the eyes had hypo-reflective area of 1.54mm2 in average. Hypo-reflective area decreased to 0.60mm2 at 6 months. Foveal reflectivity increased from 0.77 at 1 month to 0.85 at 6 months. Smaller preoperative hole base and hypo-reflective area was correlated with better postoperative visual outcomes and smaller area of postoperative hypo-reflectivity. At each visit point, visual acuity had correlation with area of hypo-reflectivity (correlation coefficient 0.42-0.63, p=0.001-0.049, Spearman’s rank correlation) and foveal reflectivity (correlation coefficient 0.35-0.61, p=0.002-0.097).
Conclusions: :
The photoreceptor layer after surgical closure of MH could be investigated in PLM using SD-OCT. Attenuated or missing IS/OS signal representing disorganization of the photoreceptor layer was shown efficiently in PLM as hypo-reflective area, which was correlated with postoperative visual acuity. Hypo-reflectivity decreased gradually after surgical closure with concurrent improvement of visual acuity.
Keywords: macular holes • imaging/image analysis: clinical • vitreoretinal surgery