[Central and peripheral corneal pachymetry--standard evaluation with the Pentacam system].

BACKGROUND: Corneal thickness measurements are important in refractive surgery, for interpretation of IOP and in corneal diseases. The purpose of this study was to generate specific standard values for the Pentacam system and to investigate the influence of body size, body mass index, body weight, gender and refraction on central and peripheral corneal thickness for a more detailed characterization of the corneal anatomy.
MATERIALS AND METHODS: The Pentacam system is based on a 180 degrees rotating computer-aided Scheimpflug camera, which generates reconstructions of the anterior segment from 12 to 50 single captures. The central corneal thickness was calculated from 25 single captures in both eyes of 182 normal Caucasian subjects (age: 18 - 83 years). The peripheral corneal thickness was measured within 3 mm distances at 0 degrees , 90 degrees , 180 degrees and 270 degrees . All subjects underwent an ophthalmological examination. Correlations between corneal thickness and body size, body mass index, body weight, gender and refraction were analyzed statistically by non-parametric tests.
RESULTS: The mean central corneal thickness of all 364 eyes was 534 +/- 36 microm. Divided into sides it was the same, 534 +/- 36 microm, in the right and in the left eyes. The mean central corneal thickness for female subjects was 533 +/- 40 microm, for males it was 534 +/- 35 microm. Statistically there was no proof of any dependence of the central corneal thickness values on the sides, gender, age, height, body mass index (BMI) or refraction. However, there was a positive significant correlation between central corneal thickness and body weight. The peripheral corneal thickness values were lowest in the temporal and inferior areas and greatest in the superior and in the nasal areas. In the superior and in the nasal areas there was a statistically significant negative correlation between age and peripheral corneal thickness.
CONCLUSIONS: The corneal thickness can be measured touchless with the Pentacam system. The central corneal thickness seems to be correlated with the body weight. Anatomical features lead to lower peripheral corneal thickness values in the temporal and inferior areas than in the nasal and superior areas. In the nasal and in the superior areas the corneal thickness seems to decrease with age. Further trials are necessary to confirm these findings and to evaluate the precision, reproducibilitiy and independence of investigators of the corneal pachymetry with the Pentacam system.