Infrared pupillometry in the assessment of autonomic function

Area of Science:

• Ophthalmology
• Neurology
• Physiology

Background:

• Dynamic pupillary function is crucial for visual processing.
• Autonomic neuropathy can affect pupillary responses.
• Establishing normative pupillary data is essential for clinical assessment.

Purpose of the Study:

• To investigate normal dynamic pupillary function in healthy adults.
• To determine reference limits for pupillary variables using infrared pupillometry.
• To assess the utility of pupillometry in detecting autonomic dysfunction in diabetic patients.

Main Methods:

• Examined 81 healthy subjects (32-60 years) and 36 type I diabetic patients using a portable infrared pupillometer.
• Measured pupillary variables including relative reflex amplitude (RRA), maximum constriction velocity (MCV), maximum redilatation velocity (MRV), and time to 75% redilatation (t75%).
• Correlated pupillary variables with age, sex, BMI, smoking habits, and autonomic function tests (Valsalva, deep breathing).

Main Results:

• Sex, BMI, and smoking had minimal effect on pupillary dynamics in healthy subjects.
• RRA was independent of age, while MCV, MRV, and t75% were strongly dependent on RRA, not age.
• Pupillometry identified abnormalities in 25% of diabetic patients without cardiac autonomic neuropathy and 50% with it.

Conclusions:

• Infrared pupillometry provides reliable reference limits for dynamic pupillary function.
• Pupillometry is a valuable tool for assessing autonomic function, particularly in diabetic neuropathy.
• Abnormal pupillary responses correlate with the presence and severity of cardiac autonomic neuropathy in diabetes.