Pre–Excimer Laser and Post–Excimer Laser Refractive Surgery Measurements of Scotopic Pupil Diameter Using 2 Pupillometers
Received 13 August 2004; accepted 1 December 2004. published online 09 May 2005.
Purpose
To compare a digital infrared pupillometer with a handheld light amplification pupillometer for measuring scotopic pupil size and to evaluate if the postoperative refractive changes of the cornea can influence pupil measurements.
Design
Prospective noncomparative interventional case series.
Participants
One hundred eyes, 50 myopic (mean spherical equivalent [SE] refraction [± standard deviation], −4.32±2.44 diopters [D]) and 50 hyperopic (mean SE refraction, +2.95±0.99 D), of 50 otherwise healthy subjects underwent photorefractive keratectomy or LASIK.
Intervention
The preoperative and postoperative scotopic pupil sizes were measured by 2 examiners (E1, E2) with both a handheld light amplification pupillometer (Colvard, Oasis Medical, Glendora, CA) and a digital infrared pupillometer (Eye World Pupillometer [EWP], Oculus Keratograph, Oculus Opikgeräte GmbH, Wetzlar, Germany). The agreement and interrater repeatability were determined using the comparison method described by Bland and Altman. The paired Student’s t test was used to evaluate the difference between the preoperative and postoperative measurements.
Main Outcome Measures
Scotopic pupil diameter, topographic corneal refractive power, uncorrected visual acuity (VA), best spectacle-corrected VA, and manifest spectacle refraction.
Results
The preoperative mean scotopic pupil diameter was 6.12±0.90 mm with the EWP and 6.18±0.91 mm with the Colvard. After the surgery, mean SE refractions were −0.22±0.98 D (myopic patients) and +0.19±0.40 D (hyperopic patients). Postoperative mean scotopic pupil diameters were 6.12±0.89 mm (EWP) and 6.17±0.90 mm (Colvard). There was no statistically significant difference between preoperative and postoperative mean scotopic pupil sizes in either patient group. The limits of agreement between the 2 devices ranged from 2.24 mm (E1) to 2.12 mm (E2) preoperatively and from 2.27 mm (E1) to 2.08 mm (E2) postoperatively. The coefficient of interrater repeatability ranged from 0.56 mm (EWP) to 1.12 mm (Colvard) preoperatively and from 0.62 mm (EWP) to 1.14 mm (Colvard) postoperatively.
Conclusions
The digital infrared pupillometer showed better preoperative and postoperative repeatability than the handheld light amplification pupillometer. In the present study, a mean correction of <3 D of the corneal refractive power did not seem to modify the preoperative scotopic pupil size measurements.
Department of Ophthalmology, University of L’Aquila, L’Aquila, Italy.
Correspondence and reprint requests to Leopoldo Spadea, MD, Via Benozzo Gozzoli 34, 00142 Rome, Italy.
Manuscript no. 2004-12.
Financial support provided by the University of L’Aquila, L’Aquila, Italy.
No author has a financial or proprietary interest in any product or company cited in the article.
ABSTRACT