![]() ![]() Mesopic (low-light) pupil size is routinely measured as part of routine medical surveillance and evaluation of employees potentially exposed to AChE inhibitors (e.g., in a failure of engineering control and subsequent breach of PPE). Materials and Methods Intervention Design and Implementation To our knowledge, this is the first publication to deal with the application of these methods in outpatient occupational medicine/toxicology. These two aims are reflected in the organization of the Results and Discussion sections. Second, this study aims to examine the feasibility and utility of pupillometer use in occupational health and military settings in response to potential exposure to organophosphates and chemical warfare agents (CWA), respectively. First, this study aims to evaluate the accuracy and precision of pupillometer use in comparisons with more common manual measurements. In addition, digital photography requires more time. 7, 8 In our setting and for our intended purposes, neither infrared digital photography nor automated pupillometry was considered feasible, as both are more time-intensive, not highly portable, and require a stable environment. Ophthalmology literature suggests that infrared digital photography and automated pupillometry may be more accurate and repeatable for measuring pupil size than the Colvard pupillometer 6 however, the Colvard pupillometer is used as a standard of comparison for novel technologies. Measurement using a pupil gauge works relatively well in normal light but is difficult in low-light conditions.ĭata demonstrate that Colvard pupillometer (specifically considered in this study) is superior to use as a card for pupil size measurement in a surgical population 6 however, to the best of our knowledge, no such data exist when considering pupil size in an occupational or military medical surveillance and response setting. Under standard clinical conditions, pupil size is measured using either a pupillometer or a pupil gauge (a card with black circles simulating pupil size in millimeter, to be compared with the patient pupil size). Numerous scientific articles have been published regarding feasible clinical methods for obtaining accurate pupil size in the fields of ophthalmology (especially refractive surgery), neurosurgery, and neurology. 5 In some exposed individuals, ocular signs and symptoms may persist for a year or more. Pupils may regain normal response to light in several days, but may take up to 9 wk to regain ability to fully dilate in dark. Duration and severity of miosis varies by exposure. Miosis can start minutes to seconds after exposure maximum miosis may not occur until an hour after exposure. This activates the parasympathetic nervous system, including in the eye, which leads to pupillary constriction. 4 Organophosphates can cause miosis, inhibiting AChE, which leads to excessive ACh. ![]() Normal pupil size is 2–4 mm in diameter in bright light and about 4–8 mm in mesopic (low-light) settings 3 one large study showed a mean mesopic pupil size of 6.45 mm (SD ± 0.82 mm). Pupillary constriction is a natural physiologic process that optimizes the amount of light that reaches the retina. In both settings, real-time, accurate pupil measurements comparing baseline and post-potential exposure pupil size could directly influence decisions regarding work or duty disposition as well as clinic care, if required. This applies similarly to dynamic military settings where it may be unclear if a service member was exposed to nerve agent or not. 1, 2 In occupational settings where workers may be exposed to AChE-inhibiting substances, determining accurate pupil size is helpful, as this could be compared with pupil size following a potential exposure event. Studies and case reports have found it to be present when other signs and symptoms are not present. The most sensitive physical exam finding in vapor exposure to AChE-inhibiting substances is miosis. Moderate exposures may cause excess salivation, lacrimation, loss of bladder and bowel control, gastrointestinal hypermotility, and emesis. This can be life-threatening with intractable seizures and respiratory collapse. Excess AChE leads to excessive acetylcholine build-up in the CNS, somatic, sympathetic, and parasympathetic nervous systems and end-organs, causing the cholinergic toxidrome. Organophosphates have been of particular interest in the military setting, given the risk of use as chemical weapons by both states and terrorists. Organophosphates, which are of interest in agriculture (as a pesticide) and military applications (chemical warfare nerve agent), inhibit AChE at nerve synapses and neuromuscular junctions. Acetylcholinesterase (AChE) is an important enzyme that helps to regulate levels of the neurotransmitter acetylcholine. ![]()
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