Abstract
Abstract: :
Purpose: CK is a surgical technique that delivers radio frequency (350 kHz) current directly into the corneal stroma through a Keratoplasty tip inserted into the peripheral cornea. Stability is a key issue in any refractive surgery procedure, but especially of concern in that laser thermal keratoplasty (LTK) also used to correct hyperopia is associated with regression (J. Refract Surg 2000 Mar-Apr; 16(2):163-9). We specifically evaluated the corneal shape changes over time, since visual acuity is subjective and can vary with accommadation. Methods: Ten consecutive patients (18 eyes) with hyperopia who had CK, as part of the IRB approved FDA trial, were evaluated. Sim Ks, predicted corneal acuity (PCA), corneal uniformity index(CU index) and corneal asphericity (Q) were measured at 12 and 24 months postoperatively utilizing the Holladay Diagnostic Summary (HDS) software of the EysSys 2000 Videokeratoscope. Auto-keratometery readings were taken at 12 and 24 months. Results: All the 18 eyes had best-spectacle corrected visual acuity (BSCVA) of 20/20 and better at month 24 except one eye (20/25). Out of 18 eyes, 16 had uncorrected visual acuity (UCVA) of 20/40 (12 with 20/20 and better) and 2 patients with 20/50 and 20/125. The mean of keratometry, Sim keratometry and Q values at 12 and 24 months is shown in Table 1. The mean Q value at 12 months was -0.06 (± 0.26) and at 24 month 0.07 (± 0.25). PC acuity was 20/25 better in all the eyes (n=18) at month 12 and at month 24. CU index was 80 % and better in all the eyes (n=18) at month 12 and at month 24. Conclusions: Analysis of the corneal shape by autokeratometry and topography post CK suggest that there is no significant change in corneal shape between 12 and 24 months, consistent with clinical data that no regression is seen after 6 months post CK. PC acuity and CU index is maintained. Asphericity (Q) of the cornea is slightly increased, which is probably not clinically significant. Supported in part by Refractec, Inc, NEI #5P30EYO1867 and Research to Prevent Blindness, Inc Table 1
Keywords: cornea: clinical science • cornea: clinical science • refractive surgery