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In idiopathic macular hole formation, Gass1 hypothesised that macular holes enlarge with displacement of the photoreceptors without tissue loss around the fovea. Jensen and Larsen2 developed binocular kinetic perimetry that could evaluate local retinal photoreceptor displacement and also confirm centrifugal photoreceptor displacement away from the foveola in eyes with a macular hole. Using the binocular perimetry technique and scanning laser ophthalmoscope microperimetry, we confirmed that the patients with a unilateral macular hole with preoperative photoreceptor displacement had better postoperative visual function when compared to patients without preoperative photoreceptor displacement.3 We also previously reported that the postoperative foveal findings were correlated with the postoperative visual function in eyes with macular hole.4
The purpose of the present study was to investigate whether or not detecting photoreceptor displacement preoperatively affects the postoperative foveal findings in eyes with an idiopathic macular hole.
Methods and results
Fifteen patients (12 women, three men; mean age 62 (SD 5) years) with a unilateral idiopathic macular hole that resolved after vitreous surgery were examined. All had undergone surgery at our institution. Eleven eyes were classified as having a stage 3 hole, four stage 2, and one stage 4. The best corrected visual acuity (VA) levels in the unaffected eyes were 0.7 or better, and no patients had ocular diseases except for mild cataract.
To detect photoreceptor displacement in eyes with the disease preoperatively, we performed binocular kinetic perimetry.2,3 The anatomical status of the repaired macular holes was assessed 3 months after the operation using optical coherence tomographic equipment (OCT 2000, Humphry Instrument, division of Carl Zeiss, San Leandro, CA, USA). Good postoperative foveal findings were defined as the presence of a foveal depression, as previously reported by Imai and associates5 (Figs 1 and 2).
Photoreceptor displacement was detected in 11 of the 15 (73%) patients preoperatively. Good postoperative foveal findings were observed in nine of the 11 (82%). Photoreceptor displacement was detected preoperatively in all nine patients. The prevalence of good postoperative foveal findings was significantly higher in patients in whom photoreceptor displacement (82%, 9/11) was detected preoperatively than in those in whom displacement was not detected (0%, 0/4) (p=0.01, χ2 test with Yates's correction). The mean preoperative VA tended to be better and the mean VA measured 3 months postoperatively was significantly better in patients in whom photoreceptor displacement was detected preoperatively (0.15 and 0.79, respectively) than in those whom it was not detected (0.08 and 0.25, respectively) (p = 0.06 and p = 0.001, respectively, unpaired t test). Visual acuities were converted to the logarithm of the minimum angle of resolution (logMAR) for statistical analysis.
Jensen and Larsen2 reported that in two macular hole patients with the longest duration of symptoms, photoreceptor displacement was not detected. The reason why patients with a macular hole with longer duration of symptoms did not have photoreceptor displacement might be that there was more damage to the displaced photoreceptors. A longer disease duration probably induced functional damage to the displaced photoreceptors, and consequently no photoreceptors are displaced from the fovea. We also reported that the detection of photoreceptor displacement preoperatively should affect postsurgical visual function, and photoreceptor damage might occur in eyes in which photoreceptor displacement was not detected preoperatively, resulting in worse postoperative visual function.3
Our results demonstrated that in patients with a macular hole in whom photoreceptor displacement was detected preoperatively, the postoperative foveal findings and visual acuities were better when compared to patients in whom displacement was not detected preoperatively. It was also reported that better anatomical foveal recovery in eyes after macular hole surgery resulted in better improvement of postoperative visual function.4 Although limitations of this study are based in its sample size, we think that a degree of preoperative photoreceptor damage influences not only postoperative visual function but also anatomical recovery.
The authors have no proprietary interest in any instruments used in this study.