Mydriatic Pupil Research Articles

Oscillatory potentials of photopic electroretinogram in artificially increased intraocular pressure in normal human eyes

Photopic electroretinograms, either to full-field light flashes (FERGs) or to contrast-reversal of square-wave gratings (PERGs) have been recorded in pigeons aged 2 years old (n = 5) and 10 years old (n = 5). Mydriatic pupil diameter, ophthalmoscopic appearance of the retinal fundus and optic media, and refractive state were comparable in the two groups. V/log I functions of individual FERG components (a-wave, b-wave and oscillatory potentials) displayed significantly lower slopes in the old birds than in the young, which suggests a reduction in retinal gain. PERG amplitude also was significantly lower in the older birds over a wide range of spatial frequencies (0.2–8.8 c/deg). Estimated visual acuity based on the extrapolated high-frequency cut off was 18 c/deg in the younger birds and 7.8 c/deg in the older birds. These results are in agreement with psychophysical data and retinal age-related losses in visual acuity, photoreceptors and retinal ganglion cells. Since these findings are comparable to those reported for humans, the results suggest that pigeons may serve as a useful model for human visual aging.

Electroretinographic changes in aged pigeons

Photopic electroretinograms, either to full-field light flashes (FERGs) or to contrast-reversal of square-wave gratings (PERGs) have been recorded in pigeons aged 2 years old ( n = 5) and 10 years old ( n = 5). Mydriatic pupil diameter, ophthalmoscopic appearance of the retinal fundus and optic media, and refractive state were comparable in the two groups. V/log I functions of individual FERG components ( a-wave, b-wave and oscillatory potentials) displayed significantly lower slopes in the old birds than in the young, which suggests a reduction in retinal gain. PERG amplitude also was significantly lower in the older birds over a wide range of spatial frequencies (0.2–8.8 c/deg). Estimated visual acuity based on the extrapolated high-frequency cut off was 18 c/deg in the younger birds and 7.8 c/deg in the older birds. These results are in agreement with psychophysical data and retinal age-related losses in visual acuity, photoreceptors and retinal ganglion cells. Since these findings are comparable to those reported for humans, the results suggest that pigeons may serve as a useful model for human visual aging.

Episodic unilateral mydriasis after neck trauma

A 29-year-old male without history of migraine developed, after whip-lash injury, episodic unilateral mydriasis lasting for several hours to a few days with a frequency of 1-2 times a week. It appeared separately on both sides associated ipsilaterally with blurred vision and moderate headache, but without other neurological or autonomic deficits. The mydriatic pupil of 7-9 mm showed sluggish or absent pupillary reactions in room light, but mostly further dilatation with prompt reactions of a slight degree in semi-darkness, and constriction after 0.5% pilocarpine instillation. During the non-mydriatic phase, it did not react to 1.25 % epinephrine, but failed to be dilated by 4% tyramine, suggesting postganglionic oculosympathetic deficit.

The effects of reserpine, l-DOPA and 5-hydroxytryptophan on 5-hydroxyindoleacetic and homovanillic acids in cerebrospinal fluid, behaviour AND EEG in cats

Four hours after injection of reserpine (0.5 mg/kg). concentrations of 5-hydroxyindoleacetic acid and homovanillic acid in cerebrospinal fluid increased by 130 and 83% respectively. Eight hours after injection, the first periods of EEG synchronization appeared coinciding with a decrease in homovanillic acid concentration. Slow-wave sleep episodes appeared at 16 hr, at which time the concentration of homovanillic acid approached control levels while the 5-hydroxyindoleacetic acid concentration remained significantly elevated. Administration of l-dihydroxyphenylalanine (50 mg/kg) increased homovanillic acid above control levels through 21 hr with a peak increase of 2428% at 4 hr. 5-Hydroxyindoleacetic acid concentration did not change significantly. The animals were alert with mydriatic pupils. The 9 hr EEG record showed desynchronization in the cortical leads, increased dorsal neck muscle tone and active eye movements. Four hours following administration of 5-hydroxytryptophan (50 mg/kg) both 5-hydroxyindoleacetic acid and homovanillic acid increased by 1120 and 75% respectively. Synchronization with short periods of low amplitude appeared during 9 hr of EEG recording. During this time the animals were awake, but demonstrated miotic pupils and recurrent periods of drowsiness. These results suggest that behaviour and EEG can be related to changes in brain monoamine metabolism measured in cerebrospinal fluid. Increased metabolism of 5-hydroxytryptamine, as indicated by increased 5-hydroxyindoleacetic acid concentration, correlates with cortical synchronization. Homovanillic acid, the major metabolite of dopamine, was increased in waking behaviour and EEG desynchronization.

Photic intermittency, pupillary diameter, and the visually evoked potential

Bызвaнныe cвeтoм кopтикaльныe пoтeнциaлы (VER) были зapeгиcтpиpoвaны y хeтыpeх лиц в ycлoвиях cиcтeмaтихecки измeняeмoй фoнoвoй пpepывиcтoй cтимyляции. VER cнaхaлa были зapeгиcтpиpoвaны y иcпытyeмых c нaтypaльными зpaхкaми (coхpaняющими пoдвизнocтъ) и зти peзyльтaты cpaвнивaлиcь c пoлyхeнными пpи pacшиpeнных зpaхкaх (мидpиaз). Aмплитyдa VER былa знaхимo бoльшe пpи pacшиpeнных зpaхкaх. B oбoих ycлoвиях aмплитyдa peaкций знaхитeльнo yмeньщaлacь пpи yвeлихeнии хacтoты пpepывиcтoй cтимyляции. Пpи пoдвизных зpaхкaх yмeньшeниe VER хacтихнo зaвиceлo oт вeлихины cyзeния зpaхкoв, a хacтихнo oт cвeтoвoй aдaптaции, пpoизвoдимoй пpepывиcтoй cтимyляциeй. B ycлoвиях мидpиaзa yмeньшeниe VER oпpeдeлялocь eдинcтвeннo тoлькo пpoцeccoм cвeтoвoй aдaптгaции в зpитeльнoй cиcтeмe.

Modified pupillary diameter and evoked potential component variation in waking cats

Peak delay and amplitude variations of three regularly appearing components of photically evoked cortical potentials were investigated in waking cats during conditions of experimentally modified pupillary diameter. It was observed that the parameters of an early component were most sensitive to modifications in pupillary diameter. When compared with mydriatic and mobile pupil values, the values for both the latency to the initial deflection and peak delay of the first appearing component were reliably longer during miosis. The amplitude of this component was also smaller during the miotic condition than during conditions of mydriatic and mobile pupils. Component values obtained during mobile and mydriatic conditions did not differ reliably.