Effect of cataract surgery on optical coherence tomography measurements and repeatability in patients with non-insulin-dependent diabetes mellitus.

PURPOSE To evaluate the effect of uncomplicated cataract phacoemulsification on macular and retinal nerve fiber layer (RNFL) thickness using two spectral-domain optical coherence tomography (OCT) instruments, Cirrus OCT and Spectralis OCT, in patients having non-insulin-dependent diabetes mellitus (NIDDM) without retinopathy, and to assess the reliability of the OCT measurements before and after cataract surgery. METHODS The study included 35 eyes of 35 patients having NIDDM without retinopathy (20 men and 15 women, mean age 69.8 years, range, 48-80 years) who underwent cataract phacoemulsification. One month before and 1 month after surgery, visual acuity and three repetitions of scans using the RNFL and macular analysis protocols of the Cirrus and Spectralis OCT instruments were performed. The differences between the two visits were analyzed by Student's t-test for paired samples. Repeatability of OCT measurements was evaluated by calculating the coefficients of variation for each of the parameters recorded and for each visit. RESULTS RNFL thicknesses provided by Cirrus and Spectralis OCT and macular measurements provided by Cirrus OCT differed significantly between the two visits. Macular thicknesses provided by Spectralis OCT before and after surgery were not significantly different. OCT repeatability was better after surgery with lower coefficients of variation for scans performed after surgical removal of the cataract. CONCLUSIONS The presence of cataracts affects RNFL and macular measurements performed with OCT in NIDDM patients without retinopathy. The repeatability of the images significantly improved after cataract phacoemulsification.