Abstract
Abstract: :
Purpose: Corneal thickness is an important clinical feature of many diseases, such as ketatoconus, corneal thinning after ocular infection, and glaucoma. Calculations based on the corneal thickness determine the limits of tissue removal in corneal refractive surgery. We analyzed the precision of rapid optical low–coherence reflectometry (OLCR), a non–contact pachymeter mounted on a slit lamp, as a new modality to measure corneal thickness. Methods: A single operator conducted measurements on the right and left eyes of seven participants on 3 nonconsecutive days within a one week time period. Seven study subjects, six women and one man with no known history of ocular disease, previous ocular surgery or contact lens wear, participated in the study. On each day, the operator took 10 sets of measurements in the right eye and then in the left eye. Each set consisted of 5 scans taken in series by the OLCR as programmed. The OLCR provided an average thickness and standard deviation for each set of measurements. Results: The range of measurements within each day for each participant was between 1.2 microns and 7.5 microns. While some participant’s measurements were statistically significantly different from one day to another, the maximum within–participant range of scan measurements over the 3 days was 11.8 microns. The within–day standard deviations of the OLCR ranged from 0.35 to 2.42 microns. The mean range for the participants over the 3 days of measurements was 6.61 (95% CI: 4.85, 8.38) microns for the right eye and 7.56 (95% CI: 5.34, 9.78) microns for the left eye. Conclusions: The measurements of central corneal thickness over the three days of study fall within a small range and small single day standard deviation. This technique appears to be more accurate than reported findings with ultrasound pachymetry. In comparison with contact techniques, the use of a non–contact system eliminates the need for topical anesthesia, causes no mechanical alteration of the anterior corneal surface, and poses no risk of infection.
Keywords: cornea: clinical science • clinical (human) or epidemiologic studies: systems/equipment/techniques • optical properties