Abstract
Purpose: :
Retinitis Pigmentosa (RP) is a set of hereditary diseases involving the gradual degeneration of the rod and cone photoreceptors. Inheritance of RP can be autosomal-dominant (AD)(30-40%), autosomal-recessive (AR)(50-60%), or X-linked (XL)(5-15%). The progression of the disease is typically measured by visual field loss. Most research in RP explores its genetic and biological aspects and, although some interest is now being focused on the natural progression of the disease, there is little information regarding visual field loss with respect to RP genetic inheritance subtypes.
Methods: :
Retrospective data were collected for 60 eyes with RP (mean age 39.5 years, range 10-59 yers) from the patient files of the Institut Nazareth et Louis-Braille (INLB) and the McGill Ocular Genetics Centre (MOGC) at the Montreal Children’s Hospital. Three visual fields (Goldmann perimeter at III4e) for each eye were scanned into Adobe Professional and their area was scored according to the weighting system of the American Medical Association. Genetic subtypes were determined by file information from the MOGC (26 AR eyes, 16 AD eyes, and 18 XL eyes).
Results: :
A significant interaction between time and genetic subtype was found (F= 2.82, p=0.028, such that individuals with X-linked RP demonstrated a less severe loss of field size between Time 2 and Time 3 than those with autosomal-dominant or autosomal-recessive RP.
Conclusions: :
While all participants with RP demonstrated a significant decline in visual field area over time, the individuals with X-linked RP showed a stabilization in visual field from Time 2 to Time 3 that was not present in those with autosomal-dominant or autosomal-recessive RP. As one of the unpredictable factors with RP is the varied progression, it is difficult to counsel individuals with RP about what they can expect. With further understanding of the progression patterns of RP based on inheritance and gene types, it will become easier to provide patients with more useful information about the expected progression of their disease. This will allow them to adjust more easily, develop appropriate expectations, and take the steps required to function well with RP.
Keywords: visual fields • degenerations/dystrophies • genetics