Cyclotorsional eye movements during a simulated PRK procedure

doi:doi:10.1038/sj.eye.6701994

Eye (2006) 20, 764–768. doi:10.1038/sj.eye.6701994; published online 1 July 2005

Cyclotorsional eye movements during a simulated PRK procedure

Presented in part at the Winter ECRS Meeting, Munich, 6–10 September 2003

None of the authors have any financial interest on the subject of the paper

A M Fea¹, L Sciandra¹, F Annetta¹, M Musso¹, M Dal Vecchio¹ and F M Grignolo¹

¹Clinica Oculistica, Universita' di Torino, Dipartimento di Fisiopatologia Clinica, V Juvarra 19, Torino, Italy

Correspondence: AM Fea, Clinica Oculistica di Torino, V Juvarra 19, 10100 Torino, Italy. Tel: +0039 011 5666048; Fax: +0039 011 539024. E-mail: antoniofea@interfree.it

Received 26 September 2004; Revised 26 April 2005; Accepted 25 May 2005; Published online 1 July 2005.

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Abstract

Purpose

Eye alignment is a serious concern when performing corneal surface ablation. Although several excimer lasers monitor horizontal and vertical movements, little is known about the potential impact of cyclotorsional movements. Dynamic cyclotorsions have been measured on 10 emmetropic subjects during a simulated PRK treatment.

Methods

Cyclotorsional eye movements were measured using a 3D videoculographic system (SMI) in 10 emmetropic subjects in upright and supine position. The subjects were wearing an eyelid speculum and were asked to fixate on a 1° red spot. The fixation target was either in focus or optically degraded by electronic filters. Data were collected at the University Eye Clinic, Torino, Italy, and the different setting measurements were compared using Student's t-test for paired data.

Results

Cyclotorsions were significantly higher when subjects were fixating an optically degraded stimulus (upright: P=0.04; supine: P=0.0002). The cyclotorsional movements ranged from -13 to 17°. A significant difference in eye orientation was present when changing from the upright to the supine position (P=0.03). Even when correcting for this positional error, significantly higher cyclotorsional movements were detected in the supine position (in focus: P=0.0043; optically degraded: P=0.0008). The torsional range was from -14.85 to 14.55°.

Conclusions

The high range of cyclotorsional eye movements during a simulated PRK procedure suggests that 3D tracking could improve surface ablation results when treating high astigmatism or when wavefront guided.