Topography-modified refraction (TMR): adjustment of treated cylinder amount and axis to the topography versus standard clinical refraction in myopic topography-guided LASIK

Purpose: To evaluate the safety, efficacy, and contralateral eye comparison of topography-guided myopic LASIK with two different refraction treatment strategies. Setting: Private clinical ophthalmology practice. Patients and methods: A total of 100 eyes ( 50 patients) in consecutive cases of myopic topography-guided LASIK procedures with the same refractive platform ( FS200 femtosecond and EX500 excimer lasers) were randomized for treatment as follows: one eye with the standard clinical refraction ( group A) and the contralateral eye with the topographic astigmatic power and axis ( topography-modified treatment refraction; group B). All cases were evaluated pre-and post-operatively for the following parameters: refractive error, best corrected distance visual acuity ( CDVA), uncorrected distance visual acuity ( UDVA), topography ( Placido-disk based) and tomography ( Scheimpflug-image based), wavefront analysis, pupillometry, and contrast sensitivity. Follow-up visits were conducted for at least 12 months. Results: Mean refractive error was -5.5 D of myopia and -1.75 D of astigmatism. In group A versus group B, respectively, the average UDVA improved from 20/ 200 to 20/ 20 versus 20/ 16; post-operative CDVA was 20/ 20 and 20/ 13.5; 1 line of vision gained was 27.8% and 55.6%; and 2 lines of vision gained was 5.6% and 11.1%. In group A, 27.8% of eyes had over -0.50 diopters of residual refractive astigmatism, in comparison to 11.7% in group B ( P<0.01). The residual percentages in both groups were measured with refractive astigmatism of more than -0.5 diopters. Conclusion: Topography-modified refraction ( TMR): topographic adjustment of the amount and axis of astigmatism treated, when different from the clinical refraction, may offer superior outcomes in topography-guided myopic LASIK. These findings may change the current clinical paradigm of the optimal subjective refraction utilized in laser vision correction.