A new method for measuring the diameter of the in vivo human cornea.

An in vivo method of measuring the size of the human cornea by using catoptric imagery as devised for both closed-circuit television and 35-mm camera systems. The system was validated by using precision reticules and casts of eyes. The reproducibility of the closed-circuit television system was +/- 0.11 mm. The mean horizontal corneal diameter (HCD) for a sample of the right eyes of 50 subjects was 12.89 +/- 0.60 mm. The system was also used to measure horizontal visible iris diameter (HVID). The mean HVID for the same sample was 11.64 +/- 0.49 mm. Although there was a good general correlation between HCD and HVID, the HVID was found to be a poor predictor of HCD for the individual eye.