Quantitative evaluation of sympathetic and parasympathetic control of iris function.

The use of quantitative measurements of pupil size as an index of autonomic nervous system (ANS) activity in normal and diabetic subjects is described. The dual innervation of the iris by the parasympathetic (PNS) and sympathetic (SNS) nervous system was demonstrated by measurement of steady-state pupil size before and after changes in ANS activity by pharmacologic agents. In the presence of total PNS blockade, dark-adapted pupil size was a reliable index of SNS activity to the iris. Latency time (time from light stimulation to initial pupil response) appeared to be a good index of PNS activity. However, increased SNS activity may also prolong the latency time. Thus, consideration of SNS activity is necessary when evaluating the latency time. In 25 diabetic subjects, there was evidence of impaired SNS activity (smaller dark-adapted pupil size during total PNS blockade) and PNS activity (prolonged latency time). In a subgroup of diabetic subjects without clinical manifestations of autonomic neuropathy and normal subjects, both dark-adapted pupil size during PNS blockade (SNS index) and latency time (PNS index) were abnormal. The coefficient of variation for these two indices was less than 5% in glycemic stable diabetic subjects. Thus, these two indices are reliable and sensitive measures of the SNS and PNS activity to the iris in normal and diabetic subjects.

The development of binocular summation in human infants.

The difference in pupil diameter between monocular and binocular viewing conditions was used as a measure of binocular luminance summation in 97 infants aged 0 to 12 months. No significant difference in pupil diameter under monocular versus binocular viewing conditions was found until the end of the fourth month of life. The age of onset was positively correlated with the age of onset for stereopsis as assessed by preferential looking. By the end of the 6th month, the difference in pupil diameter under the two viewing conditions was adult-like in magnitude. The procedure provides an objective measure of binocular function that is not affected by fixation error. The data suggest that the visual pathways by which signals from the two eyes converge are not functional until the 4th month of life.

Infrared video pupillometry: a method used to measure the pupillary effects of drugs in small laboratory animals in real time.

Pupillometry in clinical investigation and in basic research often requires dynamic measurement of pupil size. Static methods, i.e. direct observation and still photography, are often used because of the high cost of commercial infrared pupillometers and problems with pupil-iris contrast in small animals. This report describes an improved infrared video pupillometer (IVP) which accurately measures the pupil area of small animals in real time (30 samples/sec). Two components of the pupillometer were designed and built by the authors: a "bright-pupil" infrared illumination system and a digital video signal processor (VSP). The use of a standard closed-circuit television camera to produce the pupil image signal results in a device that is relatively economical to construct. The IVP is sensitive enough to accurately track pupil are in the study of the pupil light reflex or pupillary oscillations. Several applications for the IVP are illustrated, including analysis of the transient response to light flashes and intravenous injections of drug, and analysis of the spontaneous and drug-induced pupillary fluctuation. Pupillography has been applied in the bioassay of various psychopharmacologic compounds and in the assessment of narcotic dependency. This IVP is being used in this laboratory to study the pupillary action of opiates in the rabbit and rat.

Pupillometric studies in the beagle dog.

A method of measuring pupillary diameter in the dog using a Kowa RC-2 fundus camera, to which an eyepiece graticule had been fitted, is described. Pupil diameter was measured either directly by reading off from the calibrated graticule or from photographs. The pupillary diameters of 105 (53 male, 52 female) untreated English beagles aged between 8 and 32 months were measured under light intensities of 150-200 lux and 1000-1400 lux. Mydriatic and miotic pupillary diameters were measured in 62 male and 80 female dogs. Time-effect curves were plotted for two groups of 5 beagles receiving 75 mug/kg or 175 mug/kg atropine and 100 mug/kg or 300 mug/kg propantheline intravenously. The dose-effect curve for propantheline was found to be linear. A dose of 109 (97-121) mug/kg propantheline increased pupillary diameter by 3 mm, 20 min after administration. The time- and dose-effect curves, the significant sex differences and age dependency seen in this study indicate both a high degree of accuracy and the suitability of both of these methods for use in pharmacological and toxicological studies.

Head injury and the dilated pupil.

The significance of the dilated pupil in head injury is discussed. History of this condition and its possible mechanisms are described. Three patient reports are presented with unilateral dilated pupil. The literature on the subject is reviewed. Finally, the diagnostic steps which may be taken to differentiate direct third nerve injury from expanding mass lesion are suggested.

Improving diagnostic acumen in pupillary evaluation: a review for the primary care physician.

Many primary care physicians perform only a superficial pupillary evaluation as part of the physical examination. The authors review several maneuvers that require no special equipment and help to improve diagnostic yield. The "swinging flashlight" test aids in detecting a relative afferent pupillary defect. When a patient has anisocoria, the initial diagnostic challenge is to determine which pupil is abnormal. Comparing the extent of pupillary inequality under both dim and bright illumination almost always identifies the dysfunctioning pupil(s) and narrows the differential diagnosis. The authors compare third-nerve palsy and Horner's syndrome as causes of anisocoria and review light-near dissociation, another important category of pupillary dysfunction. This latter phenomenon is seen in the Argyll Robertson pupil, the dorsal midbrain syndrome, and the tonic pupil syndromes. Pupillary size and activity are key diagnostic parameters in the evaluation of patients in coma. Structural and mechanical iris defects are also frequently responsible for pupillary anomalies.