Abstract
Purpose :
Optic disc drusen (ODD) are acellular benign deposits originally reported to occur in 0.3-0.5% of the normal population. More modern studies of the normal population involving histopathology and improved imaging put the prevalence of ODD at 1.8-2.4%. ODD are understood to be associated with retinitis pigmentosa (RP) and the prevalence of ODD in individuals with RP is reported to range from 3-80%. The higher rates within this range however, of 80% (4/5 individuals) and 38% (9/24 individuals), were identified in small populations with the less common RP subtype of preserved para-arteriole RPE and more recent population studies have shown rates of 2.95-3.6%. Usher’s syndrome is also associated with elevated rates of ODD ranging from 7.6-35% depending on the subtype of Usher’s syndrome. Visible ODD may be identified on fundoscopic examination, whereas ultrasonography, OCT or autofluorescence may assist in identifying buried ODD. This retrospective study was undertaken to further investigate the prevalence of ODD using imaging techniques in an RP population.
Methods :
A database of electrophysiologically confirmed RP patients (N=195) was retrospectively examined and fundus photography, autofluorescence and OCT images were assessed in each patient for signs of ODD. Two clinicians examined fundus photographs for changes consistent with ODD. Genetic testing results were not available for all patients but were included when possible.
Results :
The prevalence of ODD was 3.1% (N=6) with 2 patients having bilateral ODD. Three of these cases were X-linked with an identified RPGR gene and three cases did not have genetic testing completed. A total of 11 patients with confirmed Usher’s syndrome and 4 patients with suspected Usher’s syndrome were examined with no patients demonstrating ODD. No individuals in this population had preserved para-arteriole RPE RP.
Conclusions :
Our results are consistent with the lower range of reported ODD prevalence. These results are more in keeping with the normal population prevalence of ODD within an RP population. The variation in results may be explained by particular subtypes of RP having stronger genetic associations with ODD. The link with RPGR is worth further investigation.
This is a 2021 ARVO Annual Meeting abstract.