Scotopic measurement of normal pupil size with the Colvard pupillometer and the Nidek auto-refractor☆
Introduction
The measurement of pupil size has become increasingly important as the pupil diameter is recognised as one of the limiting factors for visual outcome in cataract and refractive surgery, particularly in scotopic conditions. Optical phenomena, such as starbursts and glare, occur in eyes with small optical zones relative to pupil size after excimer laser refractive surgery or edge effects after intraocular lens implantation in patients with large scotopic pupils [1], [2].
Pupil size can be evaluated by various methods, of which the infrared technique has been shown to be a very reliable method of measuring scotopic pupil diameter [3], [4].
The purpose of this study was to compare pupil measurements by two infrared instruments: the Colvard pupillometer, which was designed specifically for this purpose, with the Nidek auto-refractor, which can be used to measure pupil diameter as well as its primary use an auto-refractor.
Section snippets
Methods
Healthy volunteers were recruited from the staff and relatives of patients attending a general ophthalmology clinic in Birmingham, UK.
Volunteers were excluded if they were on topical medication, had a history of eye disease, eye surgery and eye trauma. They were also excluded if they were diabetic, had a history of autonomic neuropathy, were on systemic drugs or had a history of alcohol abuse. All volunteers underwent a full ocular examination which included examination of the iris looking for
Results
Forty-six volunteers (46 eyes) were recruited for this study, 22 males and 24 females. The age range was 24–40, with a mean of 33.3 ± S.D. 3.5 years. The mean pupil diameter was 4.8 ± 0.9 mm S.D. (range 3.0–7.0 mm) with the Colvard pupillometer and 4.8 ± 0.9 mm S.D. (range 3.0–6.5 mm) with the Nidek auto-refractor at the commencement of the study in low mesopic conditions.
The mean photopic pupil diameter was 3.2 ± 0.7 mm (range 2.0–5.5 mm) with the Colvard pupillometer and 3.9 ± 0.8 mm (range 2.0–5.5 mm) with
Discussion
Galileo was probably the first to document measurement of pupil diameter and 300 years later, the significance of this in refractive surgery has been realised [7].
In refractive surgery, pupil diameter may directly influence visual performance and quality of life. When the pupil diameter is greater than the ablation zone in Excimer laser surgery, myopic blur may be expected, which reduces visual function [8] following photorefractive surgery.
If the ablation zone is smaller than pupil diameter,
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2015, Journal of Clinical AnesthesiaCitation Excerpt :In 1 patient whose right eye could not be examined, the left eye was considered. Baseline values were statistically similar to standard values reported in healthy volunteers in similar conditions [19]. Both scotopic and photopic PDs were well correlated side to side (R2 = 0.822 and 0.770, respectively), as was scotopic PD to photopic PD (R2 = 0.587 for the right eye).
Clinical performance of a handheld digital infrared monocular pupillometer for measurement of the dark-adapted pupil diameter
2010, Journal of Cataract and Refractive SurgeryCitation Excerpt :The Procyon pupillometer also had a profound negative bias, with a mean difference compared with the pupillometer we used in our study (Procyon minus NeurOptics) of −0.76 mm at 0.04 lux and −2.10 mm at 0.40 lux.17 Some authors use a wavefront analyzer or other “chin on the paper, forehead against the strap” machines to measure the pupil diameter.2,3,15,18–20 This method does not allow distance fixation and may induce accommodation, even in myopic patients, through psychogenic awareness of near.
Relationships between haloes and objective visual quality in healthy eyes
2020, Translational Vision Science and TechnologyAnalysis of various factors affecting pupil size in patients with glaucoma
2017, BMC OphthalmologyClinical analysis on the pupil diameter changes of cataract patients during phacoemulsification
2015, International Eye ScienceDark-adapted pupil diameter as a function of age measured with the NeurOptics pupillometer
2011, Journal of Refractive Surgery
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Presented in part at NIDEK International Excimer Laser User Meeting, Monte Carlo, December 2001; British Society for Refractive Surgery, Birmingham, March 2002; International Congress for Ophthalmology, Sydney, April 2002.