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Christine Kay, Sheena Bhalla; Long-term efficacy and safety of treatment of retinitis pigmentosa with valproic acid. Invest. Ophthalmol. Vis. Sci. 2013;54(15):4016. doi: https://doi.org/.
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The purpose of this study was to examine the long-term safety and efficacy of valproic acid (VPA) use in patients with retinitis pigmentosa (RP) and other retinal degenerative disorders that were offered off-label use of this drug by a previous investigator at the University of Florida. More recently, any patients currently seen at the University of Florida who had not already self-terminated use of VPA were asked to stop this drug until further prospective data on safety and efficacy is released.
This study was a retrospective chart review of all patients with retinal dystrophies who had been prescribed VPA at the University of Florida Ophthalmology Department clinic between January 2009 and April 2012. Visual field (VF), visual acuity (VA), length of treatment, liver enzymes, and side effects were analyzed. Visual field (VF) areas were defined using Goldmann visual field (GVF) tracings recorded before, during, and after VPA treatment using the V4e isopter for each eye. Areas determined by isopter V4e were converted into areas of functioning retina, as shown in figure 1.
Five of the patients (10 eyes) had two GVF tracings, allowing comparison between baseline and follow-up VF. After 9.8 months of VPA, VF decreased by 0.145 cm2 (26.478%) (p=0.432) as shown in Figure 2. For 22 of the patients (41 eyes), VA data was available, and logMAR score changed by 0.056 log units (representing a decline in VA) after 14.9 months on VPA (p=0.002). Twelve patients (38.7%) reported negative side effects related to VPA use and 9 (29%) patients discontinued VPA due to these side effects.
We found that VPA may not be an appropriate treatment for all retinal dystrophies. After an average of 9.8 months on VPA, visual field areas showed a declining trend in four out of five patients and visual acuity significantly worsened during treatment with VPA. VPA plays a complex role in patients with pigmentary retinopathy and may be associated with visual acuity and field decline as well as adverse side effects. Physicians should use caution with using VPA for pigmentary retinopathies. Effective treatment options likely depend on first identifying the disease-causing mutation and then optimizing treatment targeting genotype-specific pathology.
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