Monitoring post-lasik complications

Ophthalmologists measure central corneal thickness before and after lasik procedures to help plan the surgery and to monitor the cornea’s health afterward. Accurate measurements are important for examining patients for ocular diseases such as glaucoma, cataracts and degenerative corneal conditions. Ultrasound pachymetry — which involves placing a probe on the surface of the cornea — is the standard measurement tool.

Dr. Joseph B. Ciolino and his colleagues from the department of ophthalmology at Albany Medical College in New York recently compared the effectiveness of using a noncontact pachymetry rotating camera technique with the standard ultrasound method for measuring central corneal thickness. The researchers used the two methods to measure thickness one year after lasik in 53 patients.

A rotating Scheimpflug camera, the Pentacam manufactured by Oculus Inc. of Wetzlar, Germany, was used first. The camera rotated 360° around a single point of fixation while the patient focused on a central light source. At a steady speed, it took 25 images of each eye over about two seconds. Five images provided measurements of the central cornea’s thickness, and these values were averaged. The patient underwent ultrasound pachymetry immediately after the Scheimpflug imaging.

The mean central corneal thickness measurement found with the rotating camera was about 506 μm compared with 505 μm with ultrasound pachymetry. Because the two methods had similar results (with a correlation coefficient of 0.95), the researchers believe that the Scheimpflug rotating photography technique may be a good noncontact substitute for ultrasound in post-lasik patients. The work was published in the January issue of the American Journal of Ophthalmology.