Quantitative Anatomical Differences in Central Corneal Thickness Values Determined With Scanning-Slit Corneal Topography and Noncontact Specular Microscopy

University of Alicante, Alicante, Valencia, Spain
Cornea (Impact Factor: 2.04). 03/2006; 25(2):203-5. DOI: 10.1097/01.ico.0000176605.72129.2c
Source: PubMed


This study was designed to analyze the differences in central corneal thickness values determined with noncontact specular microscopy and scanning-slit corneal topography. The measurements were performed on the same eye.
We analyzed the central corneal thickness values of 93 patients (n = 93) by means of noncontact specular microscopy (Topcon SP-2000P noncontact specular microscope, Topcon Corp., Tokyo, Japan) and scanning-slit corneal topography (Orbscan Topography System II, Orbscan Inc., Salt Lake City, UT). One experienced physician performed 3 consecutive central corneal thickness measurements with both devices.
The central corneal thickness values obtained by means of Orbscan pachymetry were 17 +/- 2.7 (range, 12-24) microm greater. A significant correlation was observed between scanning-slit corneal topography and noncontact specular microscopy (Pearson correlation coefficient, r = 0.976; P < 0.001).
Researchers should know of the existence of this difference between noncontact specular microscopy and Orbscan pachymetry when interpreting central corneal thickness values.

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    ABSTRACT: To study the effect of 1 drop of 0.5% proparacaine on central corneal thickness values monitored by nonspecular microscopy and Pentacam, a corneal topographer with rotating Scheimpflug camera. Forty subjects were divided into 2 groups with 1 group measured with a noncontact specular microscope and the other group with Pentacam (Oculus, Inc., Wetzlar, Germany). One eye was randomly selected, and corneal thickness values were monitored every 30 seconds for 10 minutes. Baseline corneal thickness values were defined as the average of all measurements taken over 10 minutes. One drop of 0.5% proparacaine was instilled, and the corneal thickness values were monitored by the same instrument every 30 seconds for another 10 minutes after drug instillation. The 2 groups shared similar age range, refractive error, and baseline corneal thickness values. The spontaneous variation of corneal thickness values was within 3 mum for 10 minutes before drug instillation. There was no obvious trend of corneal thickness value change after the instillation of local anesthetics. The variation of corneal thickness values against the baseline was within 5 mum. One drop of 0.5% proparacaine does not produce any significant change in central corneal thickness.
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