[An objective measure of ocular torsion: a new indirect ophthalmoscopy lens]

Abstract

Purpose: Ocular torsion can be measured by different means. While subjective methods are commonly used in ophthalmological practice, objective methods are time consuming and require expensive photographic equipment. The authors present a new ophthalmoscopic lens which allows a rapid and quantitative evaluation of cyclotropia.

Patients and methods: Objective measurement of the optic nerve head (ONH)-foveal angle was performed in 30 eyes of 15 normal volunteers. Results were compared, for each subject to those obtained when measuring ocular torsion by two subjective methods: double Maddox rod and dark red glass in front of Harms' tangent screen.

Results: The new ophthalmoscopic lens showed a mean slight incyclotortion of 0.40 degrees +/- 0.20 (SEM) while Harms' tangent screen a mean slight excyclotortion of 0.12 degrees +/- 0.20 and double Maddox rod absence of torsion: 0.02 degrees +/- 0.20. No statistical difference was shown when comparing the three methods with Student paired T test.

Conclusions: The new ophthalmoscopic lens allows a rapid and quantitative evaluation of ocular torsion. Measurements can easily be performed during routine fundus examination by any practitioner.