Influence of Cataract on Time Domain and Spectral Domain Optical Coherence Tomography Retinal Nerve Fiber Layer Measurements

Purpose: To assess and compare the influence of cataract on measurements of retinal nerve fiber layer (RNFL) thickness by time domain (TD) optical coherence tomography (OCT) and spectral domain (SD) OCT. Methods: Patients who underwent uncomplicated cataract surgery were consecutively enrolled in this study. The peripapillary RNFL thickness was measured before and 8 weeks after cataract surgery using TD-OCT and SD-OCT during the same visit. Changes in the RNFL thickness measurement and signal strength (SS) after cataract surgery were evaluated. Results: A total of 54 patients (54 eyes) were included. After excluding 19 eyes owing to poor imaging or low SS (< 5), scans of 35 eyes were included in the final analysis. A significant difference was identified between the preoperative and postoperative SS values using SD-OCT, but not TD-OCT (P = 0.002 and 0.789, respectively). The changes in RNFL thickness after cataract surgery were more prominent and frequent for SD-OCT than TD-OCT. There was a significant correlation between change in preoperative RNFL thickness and SS changes for both TD-OCT (r(2) = 0.410, P < 0.001) and SD-OCT (r(2) = 0.246, P = 0.002). Conclusions: The presence of cataract significantly affects RNFL thickness measurements by SD-OCT and TD-OCT. SD-OCT, which demonstrated more consistent change of RNFL measurements after cataract extraction, is not necessarily associated with lower RNFL thickness measurement performance in cataract cases, as more participants with cataract were excluded because of poor image quality or low SS, which was more associated with TD-OCT than SD-OCT.