Search PubMed⌕ Search

SEARCH · Search PubMed

Results for “ADAPTATION, OCULAR”

Search indexed PubMed citations on genomics, clinical trials, systematic reviews and public health. Explore titles, authors and supplied subject terms, then open the PubMed record.

Quote a phrase for an exact phrase match. Source license links do not imply unrestricted reuse.

At least 847 records · Page 47Linked to original sources
PubMed1999

Accommodative error, adaptation and myopia.

Accommodative adaptation, resulting from the sustained output of slow blur-driven accommodation during the course of a sustained near-vision task, has generally been assessed under open-loop conditions. This study examined whether adaptation influences closed-loop accommodation during the course of a sustained near-vision task. Accommodative adaptation was assessed in 18 fully-corrected subjects by comparing pre- and post-task values of dark accommodation recorded objectively with an infra-red optometer. Subjects performed a continuous 10 min binocular near-vision task at a viewing distance of 33 cm, with the within-task accommodative response being assessed at 1 min intervals during this period. Subjects were categorized into adaptors (N = 11) and non-adaptors (N = 7) on the basis of whether their initial 10 sec post-task adaptation exceeded +0.30D. The adapting group exhibited a significant decline in the lag of accommodation during the first 3 min of the near-task, whereas no significant change in the within-task response over time was observed in the non-adapting group. These results indicate that accommodative adaptation increases the accuracy of the within-task, closed-loop accommodative response. Furthermore, we speculate that a deficit in accommodative adaptation, being accompanied by increased retinal defocus during near fixation, may contribute to the development of nearwork-induced myopia.

Accommodation, Ocular↗
PubMed1982

Electrophysiological evidence of adaptation to colored filters.

Subjects wore blue filters (Kodak Wratten 45) in front of their normal spectacle correction for a period of 4.5 hr. Visual evoked potential (VEP's) were measured (monocularly) before, in white light and through the blue filters at the start and finish of wearing the filters. Predictably, from the chromatic interval, the subjects initially showed some degree of myopia, confirmed by more negative lens power required to give maximum VEP response. However, after 4.5 hr of wear of the filters, VEP's were measured again and it was found that the maximum VEP response was obtained in each case with less negative lens power, indicating adaptation of the visual system toward emmetropia. The role of accommodation in this adaptive process is discussed.

Accommodation, Ocular↗
PubMed1971

Configuration dependence of scotopic spatial summation.

1. Psychophysical experiments were done under conditions of complete dark adaptation, 7 degrees in the human temporal retina, using blue-green flashes brief enough to be within the range of complete temporal summation.2. Frequency-of-seeing experiments were done for two 3.4' squares separated by 20' or 23' and for each square separately. The results were consistent with the hypothesis that the squares acted independently in determining the absolute threshold. There was no observable summation occurring between them.3. The absolute threshold (50% seeing) for two 3.4' squares (the centre-to-centre separation varied from 3.4' to 56') was measured relative to the absolute threshold for just one such square. It required more photons at the cornea at threshold for two spots than for one such spot, except when they were actually touching.4. The same subject, in the same retinal region and under otherwise identical test conditions, showed complete spatial summation at absolute threshold for circular spots up to 30' in diameter.5. Similar experiments were done on other subjects using 3.4' squares and lines of width 3.4'. All subjects showed complete summation at absolute threshold for lines 34' long. All showed lack of spatial summation for two squares unless the two squares touched to form a rectangle.6. The absolute threshold for N small spots was compared to the absolute threshold for 1 spot, where N varied from 2 to 25. Again complete spatial summation broke down even when all the spots lay within the Ricco area.7. It was shown that the results are inconsistent with the hypothesis of a linear output and a linear summation of excitations.8. Various hypotheses are examined and it is shown that no simple hypothesis can explain all the results. The conclusion is that spatial summation at absolute threshold is configuration dependent.

Adaptation, Ocular↗