Pupillary light reflex in ethambutol-induced optic neuropathy

AbstractWe evaluated changes in the pupillary light reflex (PLR) of ethambutol (EMB)-induced optic neuropathy and analyzed the correlations between PLR parameters and other structural changes in EMB-induced optic neuropathy. This retrospective, observational, case–control study involved thirty-two eyes of 17 patients with EMB-induced optic neuropathy (EON group), sixty eyes of 60 patients without EMB-induced optic neuropathy (non-EON group) while taking ethambutol, and forty-five eyes of 45 normal controls. PLR was measured by digital pupillometry. The clinical characteristics, optical coherence tomography measurements and PLR parameters including pupil diameter, constriction latency, constriction ratio/velocity, and dilation velocity were noted. The differences in PLR measurements were compared among the three groups. Correlations between PLR parameters and other structural parameters in EMB-induced optic neuropathy were evaluated. The pupillary constriction ratio, constriction and dilation velocities were significantly reduced in the EON group compared to the non-EON group and controls (all P < 0.05). In EMB-induced optic neuropathy, average outer macular ganglion cell layer (mGCL) thickness showed a significant correlation with the pupillary constriction ratio (ß = 4.14, P = 0.003) and maximal constriction velocity (ß = 1.08, P < 0.001). This study confirmed that pupillary constriction and dilation velocities were significantly decreased in patients with EMB-induced optic neuropathy, compared to normal controls. Digital pupillometry may be a useful tool in the evaluation of EMB-induced optic neuropathy.

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Characteristics of the Pupillary Light Reflex in the Macaque Monkey: Discharge Patterns of Pretectal Neurons

Journal of Neurophysiology ◽

10.1152/jn.2000.84.2.964 ◽

2000 ◽

Vol 84 (2) ◽

pp. 964-974 ◽

Cited By ~ 24

Author(s):

Milton Pong ◽

Albert F. Fuchs

Keyword(s):

Light Intensity ◽

Discharge Rate ◽

Pupillary Response ◽

Pupillary Light Reflex ◽

Physiological Data ◽

Full Field ◽

Light Reflex ◽

Pupillary Light ◽

Pupillary Constriction ◽

Discharge Patterns

Anatomical and physiological data have implicated the pretectal olivary nucleus (PON) as the midbrain relay for the pupillary light reflex in a variety of species. To determine the nature of the discharge of pretectal light reflex relay neurons, we recorded their activity in monkeys that were fixating a stationary spot while a full-field random-dot stimulus was flashed on for 1 s. Based on their discharge patterns, neurons in or near the PON came in two varieties. The most prevalent neuron discharged a burst of spikes 56 ms (on average) after the light came on followed by a sustained rate for the duration of the stimulus (burst-sustained neurons). When the light went off, nearly all neurons (33/34) ceased firing, and then all the neurons with a resting response in the dark ( n = 15) resumed firing. Both the firing rate within the burst and the sustained discharge rate increased with log light intensity and the latency of the burst decreased. The burst and cessation of firing were better aligned with the stimulus occurrence than with the onset of pupillary constriction or dilation. Taken together, these data suggest that burst-sustained neurons respond to the visual stimulus eliciting the pupillary change rather than dictating the metrics of the subsequent pupillary response. Electrical stimulation at the site of four of five burst-sustained neurons elicited pupillary constriction at low stimulus strengths after a latency of ∼100 ms. When the electrode was moved 250 μm away from the burst-sustained neuron, the elicited response disappeared. Reconstructions of the locations of burst-sustained luminance neurons place them in the PON or its immediate vicinity. We suggest that PON burst-sustained neurons constitute the pretectal relay for the pupillary light reflex. A minority of our recorded pretectal neurons discharged a burst of spikes at both light onset and light offset. For most of these transient neurons, neither the burst rate nor the interburst rate was significantly related to light intensity. We conclude that these neurons are not involved in the light reflex but subserve some other pretectal function.

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Differences in pupillary light reflex between optic neuritis and ischemic optic neuropathy

PLoS ONE ◽

10.1371/journal.pone.0186741 ◽

2017 ◽

Vol 12 (10) ◽

pp. e0186741 ◽

Cited By ~ 4

Author(s):

Yung Ju Yoo ◽

Jeong-Min Hwang ◽

Hee Kyung Yang

Keyword(s):

Optic Neuritis ◽

Optic Neuropathy ◽

Pupillary Light Reflex ◽

Ischemic Optic Neuropathy ◽

Light Reflex ◽

Pupillary Light

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Neuroticism and the Effect of Stress on the Pupillary Light Reflex

Perceptual and Motor Skills ◽

10.2466/pms.1979.49.2.635 ◽

1979 ◽

Vol 49 (2) ◽

pp. 635-642 ◽

Cited By ~ 3

Author(s):

Louise Plouffe ◽

Robert M. Stelmack

Keyword(s):

Stress Condition ◽

Pupillary Light Reflex ◽

Light Stimulation ◽

Light Reflex ◽

Pupillary Light ◽

Pupillary Constriction ◽

Effects Of Stress ◽

Post Stress

The pupillary light reflex was recorded under control, stress and fatigue conditions for 30 subjects equally divided into groups low, moderate, and high in Neuroticism. The effects of stress were distinguished by a decrease in both latency and extent of pupillary constriction during the initial light stimulation trials, as well as by a greater magnitude of redilation. Latency to maximum constriction and extent of constriction and redilation progressively decreased during the fatigue condition. No differences between Neuroticism groups were observed although it was noted that Neuroticism was negatively correlated with magnitude of redilation during the post-stress condition.

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