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Paula Y. Sacai, Adriana Berezovsky, Nivea N. Cavascan, Daniel M. Rocha, Karina S. Garan, Patricia Dotto-Turuda, Sung Eun S. Watanabee, Solange R. Salomao; Grating Acuity Maturation in Preverbal/Non-verbal Children with Nystagmus. Invest. Ophthalmol. Vis. Sci. 2012;53(14):1764.
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© ARVO (1962-2015); The Authors (2016-present)
Childhood nystagmus is associated with decreased visual acuity and can be characterized by different developmental courses of visual acuity maturation. The purpose of this longitudinal study was to investigate grating acuity maturation and deficit (GAD) in children with nystagmus measured by swept visually evoked potentials.
A longitudinal group of 33 children with nystagmus (19 males - 57.5%) had their grating acuity assessed by sweep VEP using the Power Diva system in at least three consecutive visits. Age at first visit ranged from 2 to 71 months(mean=15.7±19.5, median= 9.4). Nystagmus cases were classified into one of the following four categories: 2 isolated (normal fundus, no neurological disease,with or without strabismus/amblyopia); 19 with congenital ocular diseases (albinism, Leber’s amaurosis, cone dystrophy, aniridia, bilateral cataracts, ROP, optic nerve hypoplasia etc); 7 with cortical visual impairment and 5 with a combination of neurological and ocular conditions. Grating acuity deficit (GAD) was calculated in logMAR by subtracting acuity thresholds from mean visual acuity value using cross-sectional age norms from our own laboratory. Statistical significance was considered as p≤0.05. The rate of maturation and GAD were calculated as the slope of the best-fit line relating to logMAR GA to age in log months.
All nystagmus cases, except those two patients with isolated nystagmus, presented grating acuity below the lower normative limit. Patients with isolated nystagmus showed the fastest maturation rate and the smallest GAD along time. Patients with nystagmus associated with congenital ocular diseases showed a mild maturation rate with a trend to increasing GAD along time. Children with nystagmus associated with CVI had no significant change in grating acuity across age with a small increase in GAD along time. Those with nystagmus associated with a combination of neurological and ocular conditions showed a slow maturation rate with an increasing GAD.
Distinct visual maturation rates found in children with nystagmus were consistent with the impact that different etiological factors can have in early visual development. In this small cohort of patients, the benign visual prognosis was confirmed for isolated cases as well as the dismal visual prognosis in children with nystagmus associated with cortical visual impairment. Maturation rate and grating acuity deficit determination might be useful to assess the effectiveness of therapeutic interventions and early visual stimulation protocols for these pediatric patients.
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