Abstract
Purpose: :
To determine the effect of intrastromal segments for the treatment of keratoconus in keratometic values, spherical equivalent and visual acuity.
Methods: :
This is a prospective, nonrandomized clinical trail. All patients with diagnosis of keratoconus according to Rabinowitz's topographic criteria with the following features were included: Clear central cornea, peripheral pachometry > 450µ, central diopter power < 57.00 D, preoperative best corrected visual acuity > 20/50 and contact lens intolerance; between February and August 2005. Patients with systemic disease history, or previous corneal surgery were excluded The intrastromal segments (INTACSTM) were implanted with the following technique. Briefly, incision at steepest axis was performed at 80% of stromal depth, the segments were inserted with the conventional maneuvers, one 10–0 nylon stitch was placed, segments from 0.250 to 0.450 mm of thickness were used following Colin’s nomogram. Preoperative and postoperative at 3 month keratometric value, spherical equivalent (SE), uncorrected visual acuity with logMar conversion chart and refractive were reported.
Results: :
Twenty nine eyes of 20 patients were included, We segments' thickness was 0.450 mm in 22 cases, 0.400mm in 3 cases and 0.250 mm in 4 cases. Intacs were placed successfully in all patients, no transoperative complications were seen, the mean follow–up was 3,3 months. Mean preoperative keratometric value was 48.3 D and 44.82 D postoperatively ( p<0.01) The three patients with 0.025 mm segments, paradoxically, showed a non significant increase in keratometric values of 0.97 D, from .The mean uncorrected visual acuity was 1.18 preoperatively and 0.54 postoperatively (p>0.05), and spherical equivalent was –7.39 D preoperatively and –4.80 D postoperatively (p<0.05).
Conclusions: :
Intrastromal corneal segments provide a viable method to treat keratoconus that diminish keratometric values, improve uncorrected visual acuity and decrease spherical equivalent for patients who are contact lens intolerant.
Keywords: keratoconus • clinical (human) or epidemiologic studies: treatment/prevention assessment/controlled clinical trials • refractive surgery: other technologies