Long-term follow-up of Intacs from a single center

Abstract

Purpose: To evaluate the long-term visual results in patients having Intacs placement for the correction of mild myopia. Setting: Department of Ophthalmology, Mount Sinai School of Medicine and the Mount Sinai Hospital of Mount Sinai NYU Health, New York, New York, USA. Methods: Patients with mild myopia (spherical equivalent between −0.75 and −4.50 diopters [D]) were enrolled to have Intacs placement between May 1995 and March 1999 under United States Food and Drug Administration Phase II and Phase III clinical trials for intrastromal corneal ring segments (ICRS). Six insert thicknesses were evaluated: 0.21, 0.25, 0.30, 0.35, 0.40, and 0.45 mm. The long-term results evaluated were uncorrected visual acuity (UCVA), maintenance of best spectacle-corrected visual acuity (BSCVA), predictability and stability of the refractive effect, induced manifest refraction cylinder, slitlamp findings, self-reported visual symptoms, and maintenance of mesopic contrast sensitivity. Results: One hundred fourteen eyes of 73 patients were enrolled; 113 eyes of 72 patients received Intacs. There were no serious intraoperative or postoperative complications. The mean follow-up was 17.5 months ± 8.9 (SD). At the end of this period (number of eyes evaluated = 100), the UCVA was 20/40 or better in 95 eyes (95.0%), 20/20 or better in 72 (72%), and 20/16 or better in 41 (41%). None of the 113 eyes lost 10 or more letters or 2 or more lines of preoperative BSCVA. The mean change in the cycloplegic refraction spherical equivalent for the 6 insert thicknesses was as follows: −0.75 ± 0.00 D for 0.21 mm; −1.17 ± 0.42 D for 0.25 mm; −2.00 ± 0.54 D for 0.30 mm; −2.59 ± 0.53 D for 0.35 mm; −3.09 ± 0.54 D for 0.40 mm; and −3.82±0.80 D for 0.45 mm. The refractive correction was within ±1.0 D of the predicted outcome in 103 eyes (92.0%) and within ±0.5 D in 72 eyes (63.7%). Intacs were removed from 6 eyes (5.3%). All 4 eyes for which data were available 3 months after removal returned to within ±0.5 D of their preoperative manifest refraction spherical equivalent. Intacs were exchanged because of undercorrection in 2 eyes (1.8%). These eyes gained 3 and 5 lines of UCVA 12 months and 18 months, respectively, after the exchange procedure. Overall, 85.7% (36/42) of the patients were satisfied with the results of the Intacs procedure. Conclusions: Intacs safely and effectively corrected mild myopia. Placement is a brief, easy outpatient procedure. The refractive effect was predictable and stable over long-term follow-up. Results from a limited number of removal and exchange procedures indicate that Intacs are removable and adjustable.