Effect of Cataract and Its Removal on Ganglion Cell Complex Thickness and Peripapillary Retinal Nerve Fiber Layer Thickness Measurements by Fourier-Domain Optical Coherence Tomography

Abstract

To examine the effect of cataract on signal strength index (SSI) and thickness measurements of the ganglion cell complex (GCC) and peripapillary retinal nerve fiber layer (pRNFL) with the RTVue-100 Fourier-domain optical coherence tomography device. GCC and pRNFL measurements were obtained preoperatively in 53 eyes of 53 patients, including 13 glaucoma patients and measurements were repeated postoperatively. Cataract degree was graded by the Lens Opacities Classification System III. Factors associated with segmentation error and with changes in SSI or average thickness of GCC and pRNFL were determined. The prevalence and proportion of segmentation error were higher in GCC measurements compared with pRNFL measurements (prevalence: 28.3% vs. 5.6%, P<0.001; proportion: 5.9% vs. 1.3%, P=0.01). Multivariate analysis showed that segmentation error in GCC measurements was significantly associated with preoperative SSI and the degree of posterior subcapsular opacity. In eyes without segmentation error, postoperative SSI was significantly higher for GCC and pRNFL measurements, whereas postoperative thickness was slightly but significantly higher for all GCC and pRNFL parameters. Multivariate analysis indicated that preoperative SSI was highly correlated with SSI changes and that the presence of glaucoma and preoperative SSI were significantly correlated with average thickness changes of GCC and pRNFL, respectively. In eyes with cataract, segmentation error occurred more frequently in GCC measurements than in pRNFL measurements. After cataract surgery, all thickness parameters in GCC and pRNFL measurements increased slightly. Segmentation errors should be determined, especially in GCC measurements of eyes with cataract and low SSI.