J Korean Ophthalmol Soc.  2002 Oct;43(10):1858-1863.

Topographic Changes of Posterior Corneal Surface after Photorefractive Keratectomy with Orbscan II(R) Topography

• Kim SH
• Cho JH
• Song BJ

Abstract

PURPOSE: To investigate the relationship of refraction, geometry of the posterior corneal surface and the residual corneal thickness after excimer laser photorefractive keratectomy.
METHODS
Thirty eyes of 15 patients were treated with Star S2 Smooth Scan (VISX, U.S.A.) and followed up for 3 months. The refractive, anteroposterior changes in the posterior corneal surface and residual corneal thickness were measured using slit-scanning topography, Orbscan IIR (Orbtek, Bausch & Lomb) at 1 week preoperatively, and 1 and 3 months postoperatively.
RESULTS
Mean forward shift of the posterior cornea surface was 8.83+/-1.34 micrometer, 11.53+/-4.23 micrometer and 14.70+/-3.50 micrometer at 1 week, 1 month, and 3 months respectively. Mean spherical equivalence of posterior cornea was = -7.01+/-0.31 D preoperatively; it changed to -7.17+/-0.47 D, -7.22+/-0.21 D and -7.17+/-0.6 D at 1 week, 1 month and 3 months. The degree of forward shift of posterior corneal surface is correlated with the posterior corneal refractive changes (r=-0.808, P< 0.01). The forward shift of the posterior corneal surface is correlated with the residual corneal thickness (r=-0.483, P< 0.01).
CONCLUSIONS
Photorefractive keratectomy significantly influenced the forward shift of the cornea, which is correlated with the residual corneal thickness.

Keyword

Forward shifting; Orbscan IIR topography; PRK

MeSH Terms

Cornea
Humans
Lasers, Excimer
Photorefractive Keratectomy*