Abstract
Purpose: :
Determination of visual acuity in low vision infants or patients with additional cerebral retardation is difficult. In our low vision department we used dices of different sizes and colors as well as other defined objects to determine visual acuity (VA). In contrast to preferential looking tests not only reaction on different gratings like in preferential looking but more specific response to objects of different size and colors is observed. This allows reliable measurement even in severely handicapped patients. In this study we compared the results of the dice test with conventional measurement of visual acuity.
Methods: :
85 children with different causes of visual impairment (Albinism, retinal scars, ROP, achromatropsia, optic atrophy and others) were included over the last decades in this longitudinal study. Median follow-up was 9.3 years (3.9 - 18.9). First reliable examination was performed between 4 and 24 months (median 11 months). We estimated VA depending on edge length of the dices, which were recognized in a distance of 30 cm, while 4 mm complied with VA 20/200. Best-corrected binocular visual acuity was compared between the dice test, measurement with the Lea symbols and with numbers or Landolt rings.
Results: :
Although observation is limited to visual acuity results in the low vision range between light reaction and 20/200 there was nearly complete agreement between all three VA measurements. Visual acuity ranged from light perception to 20/20, median 20/100. In 39 patients visual acuity was 20/200 or less at the end of the observation period. Only in 2 out of the 85 patients visual acuity estimation overestimated visual acuity, while in all of the patients with later acuity measurements better than 20/200 our best value of 20/200 was achieved.
Conclusions: :
Using simple visual objects like dices with different colors and size down to an edge length of 4 mm, it is possible to estimate visual acuity in low vision infants within the first year of life. This option is as well very helpful in patients who are not able to perform other visual acuity measurements or to give reliable answers using preferential looking like severely handicapped patients. In contrast to preferential looking, with this dice test there is not only judgment of the reaction by the observer, but also activity of the patient who grips the dices he can really see. This allows better counseling of families with low vision infants concerning actual and latter visual function.
Keywords: visual acuity • low vision • vision and action