Corneal change after laer in itu keratomileui: meaurement of corneal polarization magnitude and axi

Purpoe Laer in itu keratomileui (LAIK) involve ablation of the corneal troma, which may induce a change in birefringence. The purpoe of thi tudy wa to determine the effect of LAIK on corneal birefringence by meauring corneal polarization magnitude (CPM) and axi (CPA). tudy deign Cohort tudy. Method In thi propective tudy, we meaured the change in CPM and CPA before and after LAIK with a canning laer polarimeter ([LP] GDx-VCC; Laer Diagnotic Technologie, an Diego, California). can were completed on 23 ubject before and 3 month after LAIK. 14 normal control were teted twice during the ame time interval. Change in CPM, CPA, corneal thickne, and corneal curvature meaurement were compared between LAIK and normal ubject. Reult At baeline, the mean (95% confidence interval) value of CPM, CPA, corneal thickne, and corneal curvature meaurement of the total population (n = 37) were 41.6 nm (36.6, 46.5); 31.5 degree (25.7, 37.3); 548.4 μm (540.0, 556.7); and 7.6 mm (7.5, 7.7), repectively. There were no ignificant difference in baeline value between normal and LAIK ubject. The reproducibility, meaured a the average tandard deviation of CPM and CPA meaurement in 30 normal control eye, wa 1.95 nm (1.43, 2.48) and 1.69 degree (0.92, 2.46), repectively. Mean CPA, corneal thickne, and corneal curvature meaurement were ignificantly different in patient after LAIK (all P < .0001). Mean abolute value of the change in both CPM and CPA were ignificantly greater in LAIK patient (4.8 nm [3.3, 6.4], and 10.4 degree [6.8, 14.1], repectively) than in normal ubject (2.43 nm [1.53, 3.33], and 1.64 degree [1.15, 2.14], repectively; both P ≤ .05). The abolute value of change in CPA wa linearly aociated with the abolute value of change in both corneal thickne (R2 = 0.46) and corneal curvature (R2 = 0.44). Concluion LAIK caue a meaurable change in corneal birefringence a meaured by the CPM and CPA that may be related to lo of corneal tiue. Comparion of LP meaurement before and after LAIK require eye-pecific compenation to adjut for the change in corneal birefringence