27 Feb Dark-Adapted Pupil Diameter as a Function of Age Measured with the NeurOptics Pupillometer.
Dark-Adapted Pupil Diameter as a Function of Age Measured with the NeurOptics Pupillometer.
Category: Applied Research
Bradley JC, Bentley KC, Mughal AI, Bodhireddy H, Brown SM. Dark-Adapted Pupil Diameter as a Function of Age Measured with the NeurOptics Pupillometer. J Refract Surg. 2011 Mar;27(3):202-7. doi: 10.3928/1081597X-20100511-01. Epub 2010 May 17.
Abstract PURPOSE: To measure the dark-adapted pupil diameter of normal research participants in their second through ninth decades of life using the NeurOptics pupillometer (Neuroptics Inc). METHODS: Individuals aged 18 to 80 years with no history of eye disease or injury, intraocular surgery, or use of systemic antihistamines or opiates were recruited. After 2 minutes of adaptation at 1 lux illumination, the right dark-adapted pupil diameter was measured using the NeurOptics pupillometer, with accommodation controlled by distance fixation. The NeurOptics pupillometer reported a mean dark-adapted pupil diameter and a standard deviation of the mean, which were analyzed as a function of age-decade. RESULTS: Two-hundred sixty-three individuals participated. For participants aged 18 to 19 years (n=6), the mean dark-adapted pupil diameter was 6.85 mm (range: 5.6 to 7.5 mm); 20 to 29 years (n=66), 7.33 mm (range: 5.7 to 8.8 mm); 30 to 39 years (n=50), 6.64 mm (range: 5.3 to 8.7 mm); 40 to 49 years (n=51), 6.15 mm (range: 4.5 to 8.2 mm); 50 to 59 years (n=50), 5.77 mm (range: 4.4 to 7.2 mm); 60 to 69 years (n=30), 5.58 mm (range: 3.5 to 7.5 mm); 70 to 79 years (n=6), 5.17 mm (range: 4.6 to 6.0 mm); and 80 years (n=4), 4.85 mm (range: 4.1 to 5.3 mm). These values were consistent with studies using infrared photography. The standard deviation was >0.1 mm in 10 (3.8%) participants, all of whom were younger than 55 years. CONCLUSIONS: The dark-adapted pupil diameter is an important clinical variable when planning refractive surgery. Surgeons can compare a patient’s dark-adapted pupil diameter with the results of this population study to identify outlier measurements, which may be erroneous, and repeat testing prior to surgery. Excerpt: Although geometric optics supports the psychovisual importance of the emmetropic optical zone diameter relative to the dark-adapted pupil diameter, for a period of time the refractive surgery literature held that the dark-adapted pupil diameter was an unimportant clinical variable. Despite this idea, which was well received as it increased the number of patients considered suitable refractive surgery candidates, ophthalmologists continued to measure the dark-adapted pupil diameter and new devices for this purpose were developed, marketed, and compared. Opinion on the importance of the dark-adapted pupil diameter is currently polarized, but some excimer laser manufacturers now warn patients in their product labeling about vision quality loss with large low-light pupils; the US Food and Drug Administration also warns the public of this possibility. In our opinion, if ophthalmologists measure the dark-adapted pupil diameter they should do so accurately. This requires a correct testing protocol and an accurate pupillometer. From the quality-of-practice and medicolegal perspectives, a cursory dark-adapted pupil diameter measurement is more dangerous than no measurement at all.