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M. V. Cigada, S. Simonetta, E. Cassago, R. Ratiglia; Visual Acuity and Color Vision in Preterm and Full-Term Newborns. Evaluation With Optokinetic Nystagmus. Invest. Ophthalmol. Vis. Sci. 2007;48(13):5508.
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© ARVO (1962-2015); The Authors (2016-present)
To evaluate Visual Acuity (VA) and Color Vision (CV) in newborn babies using Optokinetic Nystagmus (OKN).
OKN was examined in 96 infants (44 preterm and 52 full-term; 47 males 49 females; mean age = 73.5, range = 10 to 180 days) using a black and white (B&W) test and a modified version with colored bars. Colors were selected from Ishihara color tables # 1 and # 2.The tests were implemented on a PC screen with different grating size corresponding to a VA from 1 to 1.8 LogMAR (= 0.1 - 0.016 snellen or 20/200 - 20/1250). Both tests were repeated binocularly and monocularly, rightward and leftward. 64 of the 96 babies (mean age = 120, range = 41 to 222 days) participated at the one-month follow-up where the same tests were re-administered. Statistical analysis (regression) were made on LogMAR VA.
VA in newborns was significantly correlated with age (r=0.93). Best fitting model was represented by the reciprocal function:VA = 1 /0.49 + 0.021 * age.In other words, our prediction was that the newborns had a VA of about 2 LogMAR (snellen 0.01 = 20/2000) at birth and they reached a VA of 1 LogMAR ( snellen 0.1 = 20/200) in 237 days on average; 97% of the babies reached this VA within 266 days.When correcting data for prematurity, the model becameVA = 1 /0.49 + 0.027 * age.VA improved faster while confidence interval decreased, so that in 97% of the cases the time to reach a VA of 1 LogMAR (0.1 = 20/200) dropped to 200 days, with an average time of 188 days.Only 11 babies (11% of those responding to B&W bars) did not respond to the colored bars; none of these babies was older than 30 days (mean age = 20 days). All the other babies did respond to the same barsize, both B&W and color.No differences were found in rightward vs leftward bars movement, but 22 babies (23%) presented a temporary esotropia on the eye moving towards the nose. This percentage did not differ between full-term and preterm babies (chi square=0.88 P=ns). Similar results were found at one-month follow-up but after correcting data for prematurity we found fewer differences than in previous analysis.
According to our results VA in newborns could be lower than reported from other Authors (0.4 to 0.6 snellen). This may be due to the fact that LogMAR and hyperbolic regression were used in our study for parameters estimation.
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