Orbscan corneal topography system in evaluating the anterior structures of the human eye

To investigate the relationship among horizontal corneal diameter, corneal thickness, anterior chamber depth, pupil size, and spherical equivalent and to evaluate the variation in these parameters attributable to age, sex, iris color, and refractive state of the eye.

One thousand three hundred forty-one eyes of 688 consecutive patients who had a LASIK evaluation at World Eye Hospital were involved in the study. The information that was reviewed included age and sex of the patient, horizontal corneal diameter, corneal thickness, anterior chamber depth, iris color, pupil size (scotopic and photopic), and spherical equivalent.

The mean corneal thickness was 537.6 +/- 37.5 microm (range, 334-702). The mean anterior chamber depth was 3.5 +/- 0.38 mm (range, 1.99-4.75). The iris color was dark in 829 (61.8%) eyes and light in 512 (38.2%). The mean scotopic pupil size was 6.1 +/- 0.9 mm (range, 3.5-9.0) and the mean photopic pupil size was 4.0 +/- 0.7 mm (range, 2.1-7.4). The mean spherical equivalent was -3.4 +/- 3.7 D (range, -16.00-+7.50 D). Age was correlated with corneal thickness (r = 0.069, p = 0.012), spherical equivalent (r = 0.080, p = 0.003), and inversely correlated with corneal diameter (r = -0.367, p< 0.001), anterior chamber depth (r = -0.335, p< 0.001), scotopic pupil size (r = -0.309, p< 0.001), and photopic pupil size (r = -0.367, p< 0.001). Males had larger corneas (p< 0.001) and deeper anterior chambers (p< 0.001) than females. The eyes with a dark iris color had thicker corneas (p< 0.001), deeper anterior chambers (p< 0.001), and more minus spherical equivalents (p = 0.017) than the eyes with a light iris color.

There is a substantial range of dimensions of anterior structures of the human eye. These dimensions are related to each other and are influenced by age, sex, iris color, and refractive state of the eye.