Visual development in very low birth weight infants.

Extremely preterm infants are at risk for neurodevelopmental problems and the visual system is particularly vulnerable. However, development of visual function in preterm infants with little or no retinal or neurologic injury has not been well defined. This study compared development of visual function in preterm infants without severe retinopathy of prematurity (ROP), intraventricular hemorrhage (IVH) or periventricular leukomalacia (PVL) to that of term infants at 5-7 mo corrected age. Twenty-one very low birth weight (VLBW) preterm infants (24-32 wk gestational age, weighing < 1500 g), and 22 healthy term infants were tested at 5-7 mo corrected age. Infants with any IVH/PVL and > Stage II ROP or Plus disease were excluded. Contrast sensitivity, grating acuity, and vernier acuity were measured using swept-parameter visual evoked potentials. Thresholds and maximum amplitudes were compared between groups. VLBW and term infants showed no differences in sensitivity for contrast (67.5 versus 63.8), grating resolution (12.4 versus 12.5 cpd) or vernier acuity (1.2 versus 1.0 arcmin). However, the amplitudes for swept contrast (p < 0.03) and swept vernier offset (p < 0.04) stimuli were higher in VLBW infants. Visual thresholds in VLBW infants without serious retinal or neurologic abnormalities were not significantly different from those of term infants, suggesting that increased visual experience does not influence visual sensitivity. The higher amplitudes in VLBW infants, suggests that visual experience may affect responses to suprathreshold stimuli.

Validação clínica de teste psicofísico computadorizado para avaliação de visão de cores e sensibilidade ao contraste / Clinical validation of a computadorized psychophysical teste for color vision and contrats sensitivity

Objetivo: Avaliar a confiabilidade do teste computadorizado Two Docs para determinação da visão de cores e sensibilidade ao contraste em indivíduos adultos normais. Métodos: Trinta voluntários normais, com idades variando de 20 a 30 anos (média de 23,3 anos) foram submetidos ao TwoDocs Test para determinação de sua sensibillidade ao contraste e classificação de sua visão de cores. Seus resultados foram comparados com os dados obtidos pelas tabelas de Pelli-Robson e Farnsworth-Munsell 100 cores. Resultados: O teste TwoDocs mostrou total concordância com os resultados da sensibilidade ao contraste obtidos com a tabela de Pelli-Robson. Os testes para determinação da visão de cores não concordaram em seus resultados pois a avaliação dessa função visual por meio do teste TwoDocs foi superestimada tendo como base os resultados apresentados pelo teste Farnsworth-Munsell.

Purpose: To determine the reliability of TwoDocs computerized test for the evaluation of color vision and contrast sensitivity in normal adults. Methods: Thirty normal volunteers aged from 20 to 30 years (mean 23.3 years) had their color vision and contrast sensitivity tested by a new computerized test (TwoDocs test). Informed consent was obtained from all participants before testing. Inclusion criteria were: absence of visual complaints, absence of previous ophthalmic surgery, absence of family history of ophthalmologic diseases, best corrected visual acuity for near and distance of 20/20. Tests with the Farnsworth-Munsell 100-hue (FM-100) test for color vision assessment and the Pelli-Robson chart for contrast sensitivity measurement were also performed on the same visit, and both were considered gold standards for clinical validation. Results: The results of contrast sensitivity obtained with the Pelli-Robson chart and TwoDocs test showed agreement of 100%. Color vision results obtained with the TwoDocs test showed a strong trend to overestimate color vision classification when compared with FM-100. Conclusion: The new computerized psychophysical TwoDocs test showed a high sensitivity and specificity for contrast sensitivity measurement and can be a useful clinical tool in ophthalmology practice for this visual task. Color vision classification obtained with the TwoDocs test showed a low specificity when compared with FM-100. One possible reason for this overestimation is the computer monitor used to generate the color pattern. Additional studies in patients with disorders in color vision should be done for understanding the usefulness of this method better in clinical color vision assessment.