Long-term assessment of combined vitamin A and E treatment for the prevention of retinal degeneration in abetalipoproteinaemia and hypobetalipo-proteinaemia patients

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Abstract
Purpose To assess the long-term efficacy of combined vitamin A and E treatment in preventing retinal degeneration in patients with abetalipoproteinaemia (ABL) or homozygous hypobetalipoproteinaemia (HBL). Methods Ten patients with ABL and 3 with homozygous HBL who were treated with oral supplements of vitamins A and E were studied. Systemic, ophthalmological and electroretinographic follow-up for a mean of 11.7 years (range 4-20 years) after onset of treatment was evaluated. Results Despite vitamin A and E treatment, 7 of 10 patients who began treatment prior to 2 years of age and all 3 patients who began treatment later in life manifested unusual fundoscopic pigmentary changes over time. At the end of follow-up, 11 of 13 patients had subnormal mixed cone-rod electroretinogram amplitudes. Seven of 10 patients for whom perimetry was available had mild to severe constriction of the visual fields. Conclusions Combined oral vitamin A and E supplementation that is initiated prior to 2 years of age can markedly attenuate the severe retinal degeneration that is associated with untreated ABL or homozygous HBL. Yet, fundoscopic and functional retinal changes do occur despite early initiation of vitamin treatment. Therefore, the adequacy of the present treatment protocol for ABL and homozygous HBL should be re-evaluated.