The effect of phacoemulsification cataract surgery on the measurement of retinal nerve fiber layer thickness using optical coherence tomography

Purpose: To evaluate whether the measurement of retinal nerve fiber layer (RNFL) thickness using optical coherence tomography (OCT) changes after cataract surgery. Methods: This prospective, randomized, observational, cross-sectional clinical study included 24 eyes of 24 patients who underwent phacoemusification with implant. All patients had no preexisting retinal or optic nerve pathology or other media opacities that might influence the RNFL thickness. The classification and the grading of cataract were based on the Lens Opacities Classification System III (LOCS III). All eyes were scanned immediately before cataract surgery with OCT using Fast RNFL program. All eyes had circular scans around the optic disk with a diameter of 3.4 mm. The OCT was repeated 4 weeks after surgery when the patients returned for postoperative check using the same programme. Results: The mean preoperative RNFL thickness was 84.9 16.5. The postoperative mean RNFL thickness was 93.0 17.6. The pre-and postoperative values of the mean RNFL and signal/noise ratio (SNR) are statistically significant (P < 0.05). Conclusions: Lens opacities may affect the image quality of OCT scans used to measure RNFL thickness as indicated by preoperative low SNR. Cataract extraction results in an apparent increase of the RNFL thickness.