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C. Lawthom, P. E. M. Smith, J. M. Wild; Optical Coherence Tomography Identifies Vigabatrin-Attributed Visual Field Loss in Children and Learning-Disabled Adults. Invest. Ophthalmol. Vis. Sci. 2007;48(13):955.
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Vigabatrin (VGB) is an effective antiepileptic drug causing visual field loss in at least 40% of cases. Current usage is largely confined to children and to learning-disabled adults (LDAs). The requirement for perimetry excludes many children and LDAs from treatment with VGB. Wild et al (2006) identified an attenuated retinal nerve fibre layer (RNFL) by optical coherence tomography (OCT) as a marker of vigabatrin-attributed visual field loss (VAVL). The aim of this study was to determine whether OCT was applicable to children and LDAs and whether RNFL attenuation was also a marker of VAVL in children,
23 VGB exposed individuals, including 5 children (age 7 - 15 years) and 6 LDAs (age 20 - 57 years) who were capable of undergoing perimetry underwent, in a random order: Humphrey Field Analyzer (HFA) Three Zone 135 Point Screening Field; HFA Program 30-2 with the FASTPAC strategy; and standard 3.4 RNFL estimation at the optic nerve head using the StratusOCT III.
OCT was successfully performed in all 7 children and in 6 of the 7 LDAs (the seventh exhibited congenital nystagmus). One eye of each individual was randomly selected for analysis. Potential VAVL was evaluated by one author (JMW) who was masked to the remaining clinical data. An attenuated RNFL identified all 19 cases of VAVFL. The remaining 4 individuals exhibited an attenuated RNFL in the presence of normal fields. Average RNFL thickness was significantly correlated with the Pattern Standard Deviation (Spearman rho =-0.635, p<0.05). A further 2 LDAs and one child all with exposure to VGB, and one normal child, underwent, OCT only. All three individuals exposed to VGB exhibited an attenuated RNFL.
OCT is a sensitive and applicable tool for identifying VAVL in children and LDAs. RNFL thickness correlates with the severity of the field loss and may precede functional visual loss. Longitudinal assessment of current paediatric usage of VGB, and of putative short-term use as an anti-addiction drug should incorporate OCT which represents a breakthrough for monitoring such cases.
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