Lack of Effect of Anesthetic and Mydriatic Solutions on the Curvature of the Cornea* *From the Department of Ophthalmology, Baylor College of Medicine.

Variations in Corneal Topography

“…They claimed that the optic cap area increased but the statistical significance of these increases is not mentioned. Daily and Coe (1962) found no significant alteration of keratometric radius in 100 eyes after instillation of anaesthetic, mydriatic or cycloplegic solutions. Mandell and St. Helen (1968) reached a similar conclusion about the effect of pilocarpine.…”

The Mean Shape of the Human Cornea

“…Since the ring target contains 12 rings and 4 marked meridians a complete keratogram contains 96 rings-meridian intersection points . Occasionally, because of obstruction by the eyelids or eyelashes some of the outer rings in the Daily and Coe [14] Amano and Tanaka [15] 7 . 65 (horizontal meridian) 7 .…”

“…On the other hand, it is well established that the cornea is often toroidal, the larger radius usually being in the horizontal meridian [14], referred to clinically as 'with-the-rule astigmatism', although the nature of this astigmatism is known to vary with age [9] .…”

Dual interferometer for dynamic measurement of corneal topography

“…The average corneal shape is best approximated by an asphere with a base radius of 7.8 mm and a −0.25-conic constant, which is an oblate ellipsoid. [37][38][39] The range of radii that were measured in these studies varied from 6.7 to 9.4 mm. The distributions were normally distributed with a standard deviation of 0.3 mm about a mean of 7.8 mm.…”