Evaluation of Changes in Peripapillary Nerve Fiber Layer Thickness after Deep Sclerectomy with Optical Coherence Tomography

Abstract

To detect and quantify changes, using optical coherence tomography (OCT), in the peripapillary retinal nerve fiber layer (RNFL) thickness in patients with glaucoma who underwent deep sclerectomy. Prospective, controlled, interventional case series. Thirty-four consecutive patients who underwent monocular deep sclerectomy (surgery group) and medically treated fellow eyes (control group). Quantitative analysis of the peripapillary RNFL by OCT and automated perimetry were performed before surgery and 6 months after surgery in both eyes. The changes in RNFL thickness overall and by quadrant were evaluated and studied with respect to age, preoperative visual field test global indices, postoperative changes in intraocular pressure (IOP), and postoperative changes in visual field global indices. Changes observed in RNFL thickness were compared between eyes after surgery and in fellow eyes. The IOP decreased from a baseline mean of 23.6+/-5.1 mmHg to 11.7+/-2.9 mmHg (P<0.001) 6 months after surgery at the time of OCT testing. The mean percent IOP change was 48.4+/-15.7%. No significant changes in the mean RNFL thickness overall or by quadrant were observed after surgery or in the mean deviation (MD) and pattern standard deviation after surgery. There was no significant difference in the RNFL thickness between eyes in the surgery group and those in the control group. The mean preoperative visual field MD was significantly (P = 0.006) worse in eyes with a postoperative decrease in the overall RNFL thickness compared with those with an increase in the RNFL thickness. No correlation was found between RNFL thickness changes and age or changes in the visual field global indices. There was no significant difference between eyes with an IOP reduction of more than 50% and those with a reduction in IOP less than 30% (P = 0.514). The authors found no significant changes in the peripapillary RNFL thickness measured 6 months after deep sclerectomy. The only significant factor related to RNFL thickness changes after surgery was the preoperative visual field MD (P = 0.038).