Applications of Anterior Segment Optical Coherence Tomography in Cornea and Ocular Surface Diseases
PURPOSE To use optical coherence tomography (OCT) to measure corneal power and calculate intraocular lens (IOL) power in cataract surgeries after myopic and hyperopic laser vision correction (LVC). METHODS Patients with previous LVC were enrolled in this prospective study at two centers (Doheny Eye Institute, Los Angeles, CA, USA and Cullen Eye Institute, Houston, TX, USA). Corneal power was measured with a Fourier-domain OCT system. The intravisit repeatability of OCT corneal power measurement was evaluated by the pooled standard deviation of repeat scans. Axial length, anterior chamber depth, and automated keratometry were measured with the IOLMaster. An OCT-based IOL formula was developed. The mean absolute error (MAE) of refractive prediction for OCT-based IOL formula was calculated. The results were compared with the MAE for Haigis-L formula. RESULTS A total of 31 eyes of 24 subjects who had uncomplicated cataract surgery with monofocal IOL implantation were enrolled in the two sites. Twenty-two eyes of 16 subjects had previous myopic LVC that ranged from -12.46 D to -0.88 D. Nine eyes of 8 subjects had previous hyperopic LVC that ranged from 0.66 D to 5.52 D. The intravisit repeatability of OCT corneal power measurement was 0.24 D. For the myopic LVC group, the OCT formula had a MAE of 0.57 D compared to an MAE of 0.73 D for the Haigis-L formula (p = 0.19). For the hyperopic LVC group, the MAE for OCT and Haigis-L formula was 0.26 D and 0.54 D, respectively (p > 0.05). CONCLUSIONS Corneal power can be precisely measured with OCT. The predictive accuracy of OCT-based IOL power calculation is equal to current standards for post-LVC eyes.