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Valproic acid treatment may be harmful in non-dominant forms of retinitis pigmentosa
  1. Robert A Sisk1,2,3
  1. 1Cincinnati Eye Institute, Cincinnati, Ohio, USA
  2. 2Cincinnati Children's Hospital Medical Center, Cincinnati, Ohio, USA
  3. 3Department of Ophthalmology, University of Cincinnati, Cincinnati, Ohio, USA
  1. Correspondence to Dr Robert A Sisk, Cincinnati Eye Institute, 1945 CEI Drive, Cincinnati, OH 45242, USA; rsisk{at}

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I read with great excitement the article ‘Therapeutic Potential of Valproic Acid for Retinitis Pigmentosa’, by Clemson et al.1 Patients who received oral valproic acid (VPA) were reported to have improvement in Goldmann visual field performance and best-corrected visual acuity (BCVA) measurements after a mean 4 months of treatment. The current standard of care, vitamin A palmitate, has not been associated with any regression of disease or improvement in visual function in patients with retinitis pigmentosa (RP).2 Rather, a subgroup of patients may experience a decreased rate of cone amplitude degradation, which has been used as a surrogate marker for visual function. Therefore, this seminal work has sparked off a multicentre, prospective, randomised, controlled phase II clinical trial with the aim to evaluate the safety and efficacy of oral VPA in patients with dominant forms of RP.3 The study is currently enrolling patients, and the results will not be known until one year after the final patient is recruited.

Shortly after its publication, the study by Clemson et al was criticised for its study design, short mean follow-up …

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  • Competing interests None.

  • Provenance and peer review Not commissioned; internally peer reviewed.