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The dark-adapted pupil diameter is known to be a function of age, with older individuals having, on average, smaller pupils. Most research investigating this relationship has been conducted in laboratory settings using still or video infrared photography.1--5 Several pupillometers are now available to clinicians; however, inter-device agreement can be surprisingly poor.6 There may be a number of reasons for these discrepancies other than machine accuracy. Currently, no age-specific normative database exists for the dark-adapted pupil diameter measured with an accurate clinical pupillometer.
The purpose of our study was to measure the dark-adapted pupil diameter of a large number of healthy individuals across a wide age range using the NeurOptics pupillometer (Neuroptics Inc, Irvine, California), which is designed for clinical use.
Patients and Methods
This study was approved by the Investigational Review Board of Texas Tech University Health Sciences Center, Lubbock, Texas. Study participants were recruited from clinical and administrative staff of the Department of Ophthalmology and Visual Sciences, ophthalmology clinic patients, acquaintances of the investigators, and employees dining in the hospital cafeteria, which is adjacent to the clinic. The inclusion criterion was age between 18 and 80 years. Exclusion criteria were history of eye disease or injury that would affect the pupil shape or diameter, intraocular surgery, use of any topical ophthalmic agents other than artificial tears, and use of systemic antihistamines or opiate pain medications. Most testing was performed between 2 pm and 8 pm; participants tested between 7 pm and 8 pm were beginning an evening work shift, not leaving after a full work day, and therefore were not fatigued. No elements of an ophthalmic examination such as visual acuity or pupil light response were performed prior to dark adaptation, and if performed subsequently, were not recorded as study data.
Dark adaptation was conducted in two stages. First, participants wore wraparound "cataract" sunglasses for a minimum of 5 minutes while sitting in a dimly lit waiting room in the ophthalmology clinic. After entering the testing suite, the cataract glasses were removed and dark adaptation was carried out for 2 minutes at 1 lux diffuse ambient illumination, as measured by a light meter. Practical details of how to establish this room illumination have been described previously. 7 The participant was instructed...