[Rotational stability of the eye in standard photography]

After the implantation of a toric IOL (tIOL), postoperative rotations of more than 30 degrees have been reported. Beyond this scope, we investigated the reproducibility of the eye's orientation (rotation stability) in principle.

The rotational stability of the eye was investigated using standard fundus photographs (telecentric fundus camera, Zeiss, Oberkochen). One hundred eyes of 50 patients (28 females) were photographed in a time interval of more than 6 months twice. With the aid of significant markers on the fundus photograph, the axial position of the eye was defined and the rotational angle between the two slides of one eye was measured.

The mean absolute rotational angle was 2.4 +/- 1.7 degrees (range 0 to 7.5 degrees ) in all 100 eyes (2.5 +/- 1.6 degrees right eye, 2.4 +/- 1.7 degrees left eye). Only 6 % of the eyes did not rotate. A range of less than 3 degrees rotation was detected in 52 % of the eyes. A rotation of equal to or more than 3 degrees was noted in 42 %. The patient's age did not influence the amount of globe rotation. In- and excyclorotations showed a coincidental distribution and no side differences.

Seven and a half degrees or 3 degrees tIOL rotation would correspond to a residual astigmatism of 26 % or 10 %. When measuring the marked axis of the tIOL, these results are markedly influenced by head inclination, rotation of the head, incyclorotation or excyclorotation. This is transferable, for example, to autorefractor, corneal topography and sectorial analyses for glaucoma diagnostics.