Refractive lens exchange in keratoconus.
OBJECTIVE
To evaluate the visual results and complications of refractive lens exchange to correct myopia associated with early-stage keratoconus.


METHODS
Private practice, Siena, Italy.


METHODS
This prospective noncomparative interventional series comprised 34 consecutive eyes of 20 patients with stages I to II keratoconus. Mean patient age was 56.7 years +/- 10.4 (SD). Preoperative mean spherical equivalent (SE) was -11.0 +/- 4.65 diopters (D), (range -5.75 to -22). Ultrasound biometry was performed using videokeratographic central K-readings and the Holladay 2 formula. An intraoperative handheld autorefractor was used to check the power of implanted intraocular lenses.


RESULTS
Intraocular lens exchange due to inaccurate power occurred in 11 eyes (32%; 9 eyes intraoperative, 2 eyes postoperative). At 12 months, mean SE was -1.31 +/-1.08 D and mean defocus equivalent was 1.94 +/- 1.57 D. Twenty-two eyes (65%) were within +/-2 D of defocus equivalent, 16 eyes (47%) were within +/-1 D, and 3 eyes (9%) were within +/-0.5. Mean surgically induced astigmatism (vector analysis) was 0.54 +/- 0.43 D. Preoperative mean best spectacle-corrected visual acuity (BSCVA) was 0.55 +/- 0.20, and postoperative mean BSCVA was 0.76 +/- 0.23; the difference was statistically significant (P<.05; 95% confidence interval, 0.19 to 0.25). Postoperative mean uncorrected visual acuity was 0.48 +/- 0.25. The safety index was 1.38, and the efficacy index was 0.87. Complications were posterior vitreous detachment (9%) and dysphotopsia phenomena (15%). Corneal endothelial cell density at 12 months decreased by 6.3%.


CONCLUSIONS
Refractive lens exchange in keratoconic eyes predictably corrected myopia. However, ultrasound biometry was inaccurate in almost one third of eyes. Intraoperative autorefractometry is recommended to improve refractive outcome.
Leccisotti
Antonio
A
Ophthalmic Surgery Unit, Casa di Cura Rugani, Siena, Italy. leccisotti@libero.it
D000368:Aged; D003315:Cornea / Q000000981:diagnostic imaging / Q000503:physiopathology; D019781:Corneal Topography; D005260:Female; D006801:Humans; D007640:Keratoconus / Q000150:complications* / Q000503:physiopathology; D019654:Lens Implantation, Intraocular / Q000379:methods*; D007910:Lenses, Intraocular; D008297:Male; D033401:Microscopy, Acoustic; D008875:Middle Aged; D009216:Myopia / Q000209:etiology / Q000503:physiopathology / Q000601:surgery*; D011446:Prospective Studies; D012029:Refraction, Ocular; D012086:Reoperation; D016896:Treatment Outcome; D014792:Visual Acuity / Q000502:physiology