Two-year results of conductive keratoplasty for the correction of low to moderate hyperopia

Abstract

Purpose: To evaluate the 2-year postoperative safety, efficacy, predictability, and stability results of conductive keratoplasty (CK) to correct low to moderate hyperopia. Setting: Department of Ophthalmology, Stanford University Medical Center, Stanford, California, USA. Methods: In a prospective nonrandomized noncontrolled trial, 25 eyes of 14 patients with +0.75 to +3.00 diopters (D) of hyperopia and ≤0.75 D of cylinder were treated with CK. Low-energy, radio-frequency current was applied to the peripheral corneal stroma through a probe inserted at 8 to 32 treatment spots. An early nomogram was used in 2 eyes, and a current nomogram was used in 23 eyes; the intended refraction was plano. The 23 eyes treated with the current nomogram were analyzed for efficacy, predictability, and stability. All 25 eyes were included in the safety and patient-satisfaction analyses. Results: Preoperatively, the mean manifest refraction spherical equivalent (MRSE) in the 23 current-nomogram eyes was +1.55 D. At 2 years, the uncorrected visual acuity was 20/20 or better in 64% of eyes and 20/40 or better in 95%. The MRSE was within ±0.50 D in 64% of eyes, within ±1.00 D in 91%, and within ±2.00 D in 100%. No eye lost more than 1 line of best spectacle-corrected visual acuity or had an induced cylinder greater than 0.75 D. The mean MRSE of the cohort with all follow-ups was +0.48 D, which reflected a 29% regression from the intended plano and 43% regression from the 1-month postoperative overcorrection. The rate of regression appeared to be low and decreasing, +0.024 D per month between 12 and 24 months. A patient survey revealed improved quality of vision and a high level of satisfaction. Conclusions: Conductive keratoplasty appeared to be safe, effective, and predictable for correcting low to moderate hyperopia. Mild hyperopic regression was observed; however, the rate of regression indicated by the mean change in MRSE per month was low and decreased over the 2-year follow-up. Longer follow-up may be necessary to further characterize the refractive stability of CK.