Changes in corneal curvature in accommodation

Abstract 

Purpose

To determine the changes in corneal curvature in accommodation.

Setting

Department of Ophthalmology, St. Luke’s International Hospital, Tokyo, Japan.

Methods

Twenty-eight eyes of 14 healthy volunteers with a mean age of 38.9 years (range 28 to 65 years) were enrolled in this prospective study. Corneal topographies were taken before and during accommodation. Subjects achieved maximal accommodation by gazing at a target letter “A” in front of the eye. Keratometric values (K-values) obtained by topographies before and during accommodation were compared.

Results

Steepened corneal curvatures during accommodation were observed with the difference-plot view. Maximum K-values for the central 3.0 mm, 5.0 mm, and 7.0 mm corneal diameters significantly increased by a mean of 0.62 diopters (D) ± 0.83 (SD) (P = .0005, paired t test), 0.60 ± 0.90 D (P = .0015), and 0.72 ± 0.65 D (P<.0001), respectively. Respective minimum K-values significantly increased by a mean of 0.62 ± 0.83 D (P=.0005), 0.67 ± 0.68 D (P<.0001), and 0.64 ± 0.62 D (P<.0001). No statistically significant relationship was found between age and change in K-values.

Conclusion

The results suggest that changes in corneal curvature in accommodation participate in the mechanism of accommodation.