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Cristiane Okazaki, Olival Lago, Paulo Schor; Visual neuroadaptation in blurring conditions. Invest. Ophthalmol. Vis. Sci. 2014;55(13):2110.
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Professional divers are exposed to adverse conditions of underwater visibility. The search for objects at great depths requires an important discriminative capacity. Unprofessional divers generally do not notice the details of the environment around them, either due to the lack of searching knowledge or due to other optical and cognitive factors. The purpose of this study is to assess the central discriminative capacity in professional divers and non-divers varying the target luminosity and visual blurring.
Best corrected visual acuity of 5 divers and 7 non-diver volunteers was tested with table type ETDRS.Measurements were obtained in high contrast without filters, in low contrast and in low contrast associated to blurring. Low contrast was obtained with the aid of an automotive filter placed on the table. Blurring was obtained by positioning a aquarium tank filled with water and particles of animal protein diluted to a final blurring of 20NTU. We also compare how much turbidity is equivalent to refraction errors.
In the control group and the divers group, the ages varied from 22 to 25 and 27 to 56 years old. We calculated the difference between the quantity of identifiable letters in high contrast vision and low luminosity vision in the control group and the divers group . We also calculated the difference of the identifiable letters quantity in high contrast vision and low luminosity vision associated to blurring in the control group and in the divers group . When comparing the measurement of the non-identified letters in both groups when the automotive filter was added, that is, the difference between the high and low contrast vision, it is possible to notice a higher vision loss in the divers group than in the control group (p= 0,088). The same was noticed with higher intensity in the difference between the high contrast vision and the low luminosity vision associated with blurring (p<001).
It is possible that the significant difference between the mean age of both groups (p=0,0027) had influenced this result, eventually by differences in high order aberrations. Although we did not find results in which divers were more adapted to see in blurring or low contrast situations, it is worth to highlight that in both groups there was a significant visual loss when added turbidity and low contrast. This instrument can be interesting if applied to other study situations.
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