Prevalence of visual field loss following exposure to vigabatrin therapy: A systematic review

Abstract

SUMMARYPurpose: Vigabatrin is an efficacious antiepileptic drug licensed as add-on therapy in refractory epilepsy and used in infantile spasms. Eight years after licensing, there emerged a strong and possibly causative association with bilateral visual field loss. We report a systematic review ascertaining the magnitude of risk of vigabatrin associated visual field loss (VAVFL) and any clinical predictors of risk. Methods: Electronic searches, including MEDLINE (1966), EMBASE (1974), and CINAHL (1982, were conducted. Reports, published in full, of observational studies investigating the prevalence of visual field loss in patients with partial epilepsy treated with vigabatrin were included. Outcomes were the proportion with visual field loss, and the relative risk of VAVFL compared to similar nonexposed patients with epilepsy.Key Findings: Thirty-two studies were identified, which included 1,678 patients exposed to vigabatrin and 406 controls. Of the 1,678 exposed patients, 738 (44%) had visual field loss compared to just 30 (7%) among the 406 controls. The random-effects estimate for the proportion of adults with visual field loss was 52% [95% confidence interval (CI) 46-59]. The estimate for children was lower at 34% (95% CI 25-42). The relative risk for field loss in vigabatrin-exposed patients was 4.0 (95% CI 2.9-5.5). Larger mean cumulative dose of vigabatrin and increasing age were associated with a higher proportion of patients with visual field loss. Significance: Vigabatrin should be reserved for patients with epilepsy for whom there is no other alternative or for patients who have determined the benefit of ongoing treatment to outweigh the risk of VAVFL.

Recent Advances in the Pharmacotherapy of Infantile Spasms

“…The problem is that no reliable methods exist to detect whether or not visual field defects are developing ongoing vigabatrin therapy in infancy because they are not co-operative for perimetry assessment or measurements of the loss of retinal nerve fibre layer [32]. One recent systematic review showed that visual field defects occur in 40 % of adults and 34 % of older children receiving vigabatrin [68]. The earliest sustained onset of the vigabatrin-induced retinal defect studied by ERG is at 3 months [32].…”

Antiepileptic Drugs 2012: Recent Advances and Trends

“…There is an FDA black box warning for vigabatrin-induced, permanent, bilateral concentric visual field constriction in 30% or more of patients. [9][10][11][12][13] Peripheral visual loss can range from mild to severe tunnel vision to within 10°of visual fixation. In some cases, vigabatrin may damage the central retina, decreasing visual acuity.…”

“…The estimated risk of developing a visual field defect is 8% per year in adults. 9,13 Because of this risk of permanent visual loss, vigabatrin is available only through a single national central pharmacy. A formal ophthalmologic assessment is required at baseline and every 3 months during therapy.…”

Epileptic Encephalopathies: New Genes and New Pathways

“…Vigabatrin is very effective in West syndrome, particularly when caused by tuberous sclerosis. The drawback is the risk of vigabatrin associated visual loss (VAVL), which has been reported at levels of between 19 and 59 % in pediatric series with a median rate of 33 % [118]. Valproate and lamotrigine (LTG) are considered as a first-line treatment in LGS [33,119].…”