Rapid Return of Visual Quality After Modern LASIK
Purpose
To determine the impact of modern LASIK on subjective and objective visual quality through three months post-surgery.
Methods
In a prospective, three month, randomized study conducted under IRB supervision, an assessment of visual quality after modern LASIK was performed. Subjective results were evaluated using a patient survey. Objective assessment was based on best-corrected distance visual acuity (BDVA), uncorrected distance visual acuity (UDVA), contrast sensitivity, and assessment of the Objective Scattering Index (OSI). Contrast sensitivity, MTF cutoff, Strehl ratio, and OSI, an interpretation of the point-spread function, were obtained using a double-pass technique. Enrollment criteria included preoperative myopic spheroequivalent between -1.00D and -7.00 D with up to 3.00D of cylinder and preoperative BDVA of 20/20 or better. Subjects underwent bilateral modern LASIK using the Alcon FS200 femtosecond laser and EX500 excimer laser by one surgeon (DSD). Subjects were evaluated at baseline, 1 day, 1 month, and 3 months.
Results
Results from 26 eyes of the 13 patients who have completed the three month exam are presented. At Day 1, visual quality as measured using the OSI worsened from 0.54 ± 0.37 to 0.79± 0.52 (p =0.029). Subjective independence from glasses and overall visual quality were significantly improved (p<0.05). At both 1 and 3 months, the OSI was no longer statistically different from baseline. At 3 months, subjective independence from glasses, overall visual quality, and now glare were significantly improved from baseline (p<0.05). OSI, Strehl ratio, CV100, CV20, CV9, average MTF, and MTF cutoff were statistically unchanged. Monocular UDVA of 20/20 and manifest S.E. of ± 0.50 or better was present in all eyes. The study is ongoing.
Conclusion
Early findings from this prospective study show improved visual recovery after LASIK compared to previous reports and suggest that objective assessment of visual quality based on optical scatter with a double pass technique agree with subjective reports. Transient reduction in subjective and objective visual quality returned to baseline by one month by both objective and subjective metrics. By three months, patients also reported a statistical reduction in glare compared to the preoperative baseline.