Abstract
Purpose: :
To provide clinicians with reference data for the normal range of dark-adapted pupil diameter (DAPD) of patients in the second through eighth decades of life and to determine the effect of gender and iris color.
Methods: :
Subjects aged 18-80 years (N = 263) with no history of eye disease or injury, intraocular surgery, or use of systemic antihistamines or opiate medications participated in the study. Pre-adaptation was conducted by having the subject wear wraparound "cataract" sunglasses for five minutes in a waiting area. Dark-adaptation at 1 lux illumination was conducted for 2 minutes in a room without focal light sources. While the subject gazed steadily with the left eye at the opposite wall to eliminate accommodation, the right DAPD was measured with the NeurOptics pupillometer (NOP). The NOP reported a mean DAPD and a standard deviation (SD) of the mean. A high-resolution digital slit lamp photograph of the iris was then taken, and iris color was subjectively classified as blue, blue-green, green-brown, light brown, or dark brown. The digital photographs were objectively measured with the Minolta TV Color Analyzer II using Commission Internationale d'Eclairage (CIE) system of color description. The SD of the DAPD as a function of age was performed as well as regression analyses to identify correlations between subjective color, CIE measurements and DAPD.
Results: :
For subjects aged 18-19 years (N = 6), the mean DAPD was 6.85 mm (range 5.6-7.5 mm); 20-29 years (N = 66), 7.33 mm (5.7-8.8 mm); 30-39 years (N = 50), 6.64 mm (5.3-8.7 mm); 40-49 years (N = 51), 6.15 mm (4.5-8.2 mm); 50-59 years (N = 50), 5.77 mm (4.4-7.2 mm); 60-69 years (N = 30, 5.58 mm (3.5-7.5 mm); 70-79 years (N=6), 5.17 mm (4.6-6.0 mm); 80 years (N=4), 4.85 mm (4.1-5.3 mm). These values were consistent with those reported from a previous study using infrared photography. The SD was >0.1mm in 10 subjects (3.8%) all of whom were <55 years of age. Gender had no effect on the DAPD. Iris color had no effect on the DAPD. The Minolta device was simple and efficient to use.
Conclusions: :
The DAPD is an important clinical variable when planning refractive surgery. Surgeons can compare a patient's DAPD with the results of this population study to identify outlier measurements which may be erroneous, and repeat testing prior to surgery. Contrary to long-held beliefs, female patients and blue-eyed patients do not have larger DAPD. Digital color sensing is a useful technique for objectively describing iris color.
Keywords: pupil • refractive surgery: optical quality • aging