Measurement of posterior corneal asphericity on Hong Kong Chinese: a pilot study

The posterior corneal p-value and apical radius of 60 Hong Kong Chinese were assessed. The values were derived based on the information of the anterior corneal topography and the corneal thickness in different regions. The mean posterior corneal apical radius along the horizontal meridian was 6.51 mm (SD +/- 0.40 mm) and the p-value was 0.34 (SD +/- 0.38). The apical radius is greater while the p-value is smaller than a previous study using a similar principle. This may indicate a flatter posterior cornea and greater peripheral flattening in Hong Kong Chinese. No significant difference between the nasal and temporal corneal thickness, nasal and temporal posterior p-value and apical radius was demonstrated. The right and left eyes were also similar in different ocular parameters apart from a smaller anterior corneal p-value on the right eye (R eye: 0.70 +/- 0.13; L eye: 0.67 +/- 0.12), but the difference may not be significant clinically. The method used here is simple and the generation of posterior corneal topography is informative.