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Results for “ADAPTATION, OCULAR”

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At least 1,387 records · Page 77Linked to original sources
PubMed1983

Illuminance and recording of eye movements by electro-oculography.

The fluctuation of the d.c. potential of the eye following changes in the ambient level of illuminance is well recognised in the field of ophthalmology. However, the influence of this factor in the recording of eye movements in the oto-neurological clinic has been little investigated. In this study the variation in the d.c. potential was measured for fixed periods of time after subjects entered a clinic environment of known illuminance and after entering the dark. In the short term (3-4 min), the variation in d.c. potential was less than 20% in the 22 subjects tested. Suggestions are made to minimise these fluctuations in the recording of nystagmus and other eye movements.

Adaptation, Ocular↗
PubMed2001

Effects of light and darkness on cell deaths in damaged retinal ganglion cells of the carp retina.

Effects of light and darkness on the apoptosis of retinal ganglion cells (RGCs) in young carp were measured by TUNEL method after transection of the optic nerve. Following the operation, the fish were kept under one of four regimens; constant darkness (DD), constant light (LL), 12 hr light and 12 hr dark (LD) and 3 hr of flickering light followed by 21 hr in the dark (FL). On day 3, the highest ratio of apoptotic RGCs was seen under conditions of DD, followed by LL, LD, and FL. On day 6, the percentages of apoptotic RGCs were lower under every experimental condition than what they had been earlier on day 3, but the same ranking order was maintained. Immunohistochemically it could be shown that phosphorylated ERKs were more intensively localized in FL rather than DD retinas. The results suggest that illumination regimens, and in particular cyclic diurnal light/dark changes, have an influence on the degree of apoptosis of damaged RGCs, and that inhibition of apoptosis is correlated with the higher expression of phosphorylated ERKs.

Adaptation, Ocular↗
PubMed1990

[Primary study of iontophoresis of zinc ion in treatment of retinitis pigmentosa].

We report here the preliminary effects of zinc iontophoresis in treatment of 26 Rp patients who had decreased zinc serum level or abnormal ratio of serum copper to zinc. Through more than 20 to 30 times of therapy, the vision of 15.38% eyes increased more than "3 lines", 4% eyes increased more than 5 degrees in the visual field, 13.46% eyes improved in dark adaptation threshold (greater than 1.0), the visual functions of the rest eyes were slightly improved or unimproved. The fundus didn't change before & after treatment. There were no changes of ERG in 8 eyes of 4 cases. In addition, the advantages and disadvantages between Zn iontophoresis and Zn compound taken orally, the improvement of vision by direct electric current therapy, the relationship between the metabolism of Zn element and Vit A and influence of Zn over the mechanism of dark adaptation were also briefly discussed.

Adaptation, Ocular↗
PubMed1990

[Ocutrast--a new procedure for measuring mesopic visual acuity and glare sensitivity].

Measurements of glare sensitivity and mesopic visual acuity are becoming increasingly important for clinical use. They can help to trace indications for cataract operation at an early stage or for YAG laser capsulotomy in cases of mild capsular fibrosis. Up to now, there are no standardized methods for monocular and binocular measurements. A new instrument named Ocutrast has been developed. A study of 100 healthy subjects aged up to 60 years was carried out. Under a field luminance of 1.0 cd/m2 and a contrast of 1:23, visual acuity was measured without and with glare. Standardized conditions were guaranteed. The mean values were lower at higher age, but were not reduced under glare. Additionally two groups of patients (n = 50) were examined. In cataract eyes and in pseudophakic eyes a one line reduction of mesopic visual acuity under glare was found. The conclusion is: a two line reduction of mesopic visual acuity between measurements without and with glare can be regarded to be out of range. Under clinical aspects, this method can contribute to the indication to cataract operation or to YAG laser capsulotomy in pseudophakic eyes.

Adaptation, Ocular↗