Age-related differences in normal corneal topography.

BACKGROUND AND OBJECTIVE

The aim of this study was to compare age-related differences in the corneal topography of a normal population using a computerized corneal topography system.

PATIENTS AND METHODS

The randomized comparative study included 240 eyes of 120 subjects with normal corneas. Subjects were divided into six age groups: 5 to 10 years (group 1), 11 to 20 years (group 2), 21 to 30 years (group 3), 31 to 40 years (group 4), 41 to 50 years (group 5), and 51 years or older (group 6). Average corneal power and corneal astigmatism were examined. An average corneal topography map was constructed and the astigmatism pattern was determined in each age group.

RESULTS

Average corneal power values were 41.64 +/- 0.85 diopters (D), 42.35 +/- 0.90 D, 42.63 +/- 0.99 D, 42.94 +/- 0.93 D, 43.38 +/- 0.77 D, and 43.53 +/- 0.88 D in groups 1 to 6, respectively (P < .001). Mean astigmatism values were similar in all age groups (P = .225). Younger subjects had with-the-rule astigmatism, but older subjects showed a shift to oblique or against-the-rule astigmatism. The averaged maps of groups 1 to 3 showed a vertical bow-tie pattern, but the central steep area gradually extended horizontally and it became a round configuration in groups 4 to 6.

CONCLUSION

This study suggests that the normal cornea becomes steeper in the horizontal line and superior vertical quadrant and shifts from with-therule to against-the-rule astigmatism, but the amount of physiological corneal astigmatism does not change with age.