Retinal dysfunction and anterior segment deposits in a patient treated with rifabutin.

PURPOSE: To describe the clinical and electrophysiological findings in a young boy with decreased vision possibly due to retinal damage by rifabutin. METHODS: An 8-year-old boy with osteomyelitis was referred due to visual disturbance. During a period of 4 years, the boy was examined six times with electroretinography. Ophthalmological examination included testing of visual acuity, slit-lamp inspection, fundus inspection, fundus photography and kinetic perimetry. Two electrophysiological methods were performed for objective evaluation of retinal function, namely full-field electroretinography and multifocal electroretinography. RESULTS: We found a slightly reduced visual acuity, a slowly increasing amount of yellow-white deposits on the posterior surface of the cornea and on the anterior part of the lens, a normal fundus appearance, and normal visual fields. However, the electroretinogram was abnormal on several occasions during therapy with rifabutin, but returned to normal 3 months after withdrawal of the medication. The multifocal electroretinogram returned to normal after the full-field electroretinogram had done so. The anterior chamber deposits still remain. CONCLUSION: Long-term treatment with rifabutin may have a reversible and previously undescribed side-effect on retinal function. The drug may also accumulate irreversibly on the posterior surface of the cornea and on the anterior surface of the lens. We suggest that objective evaluation of retinal function with electrophysiological methods should be performed in patients with visual disturbance during treatment with rifabutin.

Electrophysiological findings in two young patients with Bothnia dystrophy and a mutation in the RLBP1 gene.

PURPOSE: To characterize the clinical phenotype, with emphasis on electrophysiology, of two children with suspected Bothnia dystrophy. METHODS: Two unrelated affected patients, 10 and 11 years old, were studied. Ophthalmological examination included testing of visual acuity, fundus inspection and fundus photography, kinetic perimetry, full-field electroretinogram (ERG), and multifocal ERG. The presence of a mutation in exon 7 of the RLBP1 gene was investigated by DNA sequencing. RESULTS: Both patients were homozygous for the Arg234Trp-causing mutation in the RLBP1 gene, but the resulting disease phenotype appeared to vary somewhat between them. Visual acuity was moderately reduced in one patient and normal in the other. Fundus inspection at this age revealed no pathology in either patient and there were no signs of retinitis punctata albescens, which has been described previously as a frequent clinical feature of Bothnia dystrophy. The result of kinetic perimetry was normal. The final rod threshold was moderately elevated. Full-field ERG demonstrated the uncommon combination of absent rod response and normal cone response after 40 minutes of dark adaptation. However, after prolonged dark adaptation (20-24 h), both the rod response and the dark adaptation threshold became normal. Multifocal ERG was performed in one of the patients (the one with normal visual acuity and normal fundus appearance) and showed a reduced cone response in the central region of the tested area. There was no improvement of the multifocal ERG result after 20-24 h of dark adaptation. CONCLUSION: Patients with mutations in the RLBP1 gene (Arg234Trp) may have a normal fundus appearance early in the disease course. Multifocal ERG can be used for the objective documentation of the disturbed macular function, especially when the patient's visual acuity and fundus appearance are normal. The rod response is absent in the electroretinogram; however, after prolonged dark adaptation (20-24 hours), the rods recover completely. The central cones do not seem to recover.