Format

Send to

Choose Destination
J Refract Surg. 2012 Apr;28(4):275-9. doi: 10.3928/1081597X-20120221-03. Epub 2012 Mar 1.

Scheimpflug camera measurement of anterior and posterior corneal curvature in eyes with previous radial keratotomy.

Author information

1
SEKAL Rovigo Microsurgery, Rovigo, Italy.

Abstract

PURPOSE:

To compare the anterior and posterior corneal curvature in eyes with previous radial keratotomy (RK) to normal unoperated eyes.

METHODS:

In this retrospective observational case series, 29 eyes from 29 consecutive patients were analyzed and compared to a control group of 71 unoperated eyes. Corneal imaging was obtained by a rotating Scheimpflug camera (Pentacam, Oculus Optikgeräte GmbH). Anterior and posterior corneal curvature radii were measured at the 3-mm zone.

RESULTS:

The mean anterior and posterior corneal radii were 9.54 ± 0.89 and 8.54 ± 1.01 mm, respectively, both values being significantly higher than in the control group (7.81 ± 0.28 and 6.40 ± 0.24 mm, respectively, P<.0001). The mean anterior-to-posterior corneal curvature ratio was 1.12 ± 0.07, a value significantly lower than in the control group (1.22 ± 0.03, P<.0001). Mean corneal flattening was more evident in the posterior (33.44%) than in the anterior (22.15%) corneal curvature. The mean keratometric index, as calculated with the Gullstrand equation for thick lenses, was 1.3319 ± 0.0026, a value significantly higher than in the control group (1.3281 ± 0.0011, P<.0001). Linear regression detected a significant and directly proportional relationship between the number of radial incisions and flattening of both corneal surfaces (P<.0001).

CONCLUSIONS:

After RK, both corneal surfaces flatten but do not deform in parallel as commonly accepted, as shown by the fact that the anterior-to-posterior corneal curvature ratio decreases. This finding invalidates the standard keratometric index and thus has relevant implications for intraocular lens power calculation in RK eyes.

PMID:
22386371
DOI:
10.3928/1081597X-20120221-03
[Indexed for MEDLINE]

Supplemental Content

Full text links

Icon for SLACK Incorporated.
Loading ...
Support Center