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Natasha Healey, Kathryn J. Saunders, Julie F. McClelland, A J. Jackson; Refractive Error and Emmetropisation in Albinism and Congenital Nystagmus. Invest. Ophthalmol. Vis. Sci. 2011;52(14):5719. doi: https://doi.org/.
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© ARVO (1962-2015); The Authors (2016-present)
Albinism is an inborn error of melanin metabolism (incidence 1 in 18,000). Oculocutaneous (OCA) and ocular albinism (OA) exhibit similar ocular and visual dysfunction, including high refractive errors and nystagmus. Nystagmus may also occur in isolation with significant effects on the developing visual system. It is presently not clear how albinism impacts on emmetropisation and whether these effects are primarily due to the impact of albinism or nystagmus. The present study aims to examine the refractive profile of individuals with albinism and congenital nystagmus (CN) attending a low vision clinic.
Retrospective data from 148 patients with albinism (n=93) or CN (n=55), attending low vision and refraction clinics at the Royal Group of Hospitals Belfast over a 24 year period (1986-2010), were examined.
Results demonstrated a significant difference between the two groups in terms of age at first visit (ANOVA p<0.05) with those subjects with albinism presenting earlier than those with CN. Subjects with albinism had a wider range of refractive errors (spherical component ranged between -13.00DS and +15.00DS for albinism and between -6.00DS and +8.00DS with CN; cylindrical errors ranged from 0 to -7.00DC for albinism and 0 to -4.50DC for CN). Subjects were classified into the following age groups; age ≤0.5 year, 0.5 to ≤1 year, 1 to ≤4 years, 4 to ≤8 years , 8 to ≤12 years, 12 to ≤16 years and >16 years. Subjects with albinism aged from 12 months to 12 years had significantly higher spherical error, spherical equivalent, most ametropic meridian, cylindrical error and J0 component than those with CN (ANOVA p<0.05). Beyond 12 years of age no statistically significant differences were found between the two groups’ refractive status.
Albinism and congenital nystagmus appear to affect the emmetropisation process differently. Additional ocular defects in individuals with albinism may be responsible for more extreme levels of refractive error.
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