ABSTRACT
Objective To observe the clinical efficacy of rigid gaspermeable contact lens (RGPCL) for correcting keratoconus and analyze the predictors for the base curve of RGPCL.Methods Data of 86 patients (143 eyes) with keratoconus fitted with RGPCL were retrospectively analyzed.All eyes were divided into the mild (n =18 eyes),moderate (n =73 eyes),advanced (n =34 eyes) and severe group (n =18 eyes).After evaluating the lens fitting,best corrected visual acuity of eyes wearing spectacle lenses and RGPCL among the 4 groups was statistically compared.And the correlation between the fitting guidance index and HL-K RGPCL base curve in each group was analyzed according to keratometry.Results All patients wearing RGPCL gained significantly better corrected vision in the mild (t =-3.336,P =0.004),moderate (t =-11.213,P ＜0.001),advanced (t =-13.959,P ＜0.001) and severe groups(t =-11.047,P ＜0.001) than those with spectacles.Equivalent spherical degree of spectacle lenses was lower than the diopter of HL-K RGPCL in the moderate (P =0.043) and severe group (P =0.006).The mean base curve of RGPCL was (50.52 ±5.64) diopter,and it was correlated with corneal curvature parameters.In mild group,the RGPCL base curve was correlated with the steep keratometry (P ＜ 0.001).The average K and relative steep K of 0.2 mm (Rm-0.2) were highly correlated with RGPCL base curve in moderate group (r =0.798,P ＜ 0.001;r =0.798,P ＜ 0.001),in advanced group (r =0.745,P ＜ 0.001;r =0.745,P ＜ 0.001) and in severe group (r =0.616,P =0.007;r =0.617,P =0.006).Conclusion Patients with keratoconus wearing HL-K RGPCL can obtain ideal corrected vision.Determination of RGPCL base curve by adjusting the corresponding indicators is conducive to improving the long-term wearing safety of the lens and enhancing the efficiency of lens fitting.