Las Vegas-Conductive keratoplasty ([CK] NearVision, Refractec) performed after LASIK resulted in high subjective patient satisfaction and improved functional near vision 3 months after treatment in a preliminary study of patients with presbyopia who have undergone myopic LASIK.
"When considering CK as a LASIK enhancement procedure, there are many advantages of using CK after LASIK," Erin D. Stahl, MD, said at the American Academy of Ophthalmology annual meeting. "CK is very safe, some of the risks of lifting the LASIK flap such as epithelial ingrowth and diffuse lamellar keratitis are avoided, and with CK there is some improvement in the near vision while preserving the distance vision."
The study included 150 eyes of 150 subjects who had undergone LASIK for myopia at least 1 year previously. The range of the spherical equivalent (SE) before LASIK was –1.0 to –6.0 D. All patients were emmetropic ±0.5 D after LASIK, and all were presbyopic. All patients had less than 0.75 D of cylinder. The central corneal thickness in all patients was greater than 400 µm, and the peripheral thickness was greater than 560 µm. The patients needed about +1.24 D of add for near vision. The CK treatment plan was conservative, according to Dr. Stahl, with application of eight spots on the outer ring at 8 mm. Dr. Stahl is a resident at the University of Kansas in Kansas City.
Good safety, efficacy
"At 1 and 3 months after CK, the safety profile of CK was excellent, with no eyes having lost more than 2 lines of best spectacle-corrected visual acuity (BSCVA) at distance, no loss of vision that exceeded 20/40 BSCVA at distance, and no greater than two lines of induced cylinder," she reported. No adverse flap complications occurred.
Regarding efficacy, 95% of patients had J3 or better vision 3 months after CK, and 97% of patients were within 1 D of the attempted correction.
"The mean effect was 1.16 D at 3 months, which was just undercorrected from the 1.25 D of attempted correction," she said.
In commenting on the stability of CK, Dr. Stahl reported on the results of a different study of conventional CK over time in patients with presbyopic emmetropia. Over 2 years, progression of hyperopia of 0.25 D was seen in the nine eyes followed in this study. In the contralateral eyes of these patients, similar progression of hyperopia was seen. "We believe that CK is a stable procedure and that the progression of hyperopia is the natural course of refractive change in this age group," she said.
The subjective results showed that patients could read golf score cards and newspapers and believed that they did substantially better than they did preoperatively.
"The patients felt that they were less dependent on glasses for near vision and intermediate vision than they were preoperatively. Eighty-five percent of patients were satisfied or very satisfied at the 3-month time point. The quality of depth perception was unchanged postoperatively from preoperatively," she reported.