Purpose:
To analyze and classify atypical fundus findings in a 20-year old male with Prader Willi-syndrome.
Methods:
In addition to basic ophthalmological examinations the following methods were applied: SD-OCT, standard and near-infrared autofluorescence, fluorescein and ICG-angiography, colour perception, standardized ERG and visual evoked potential recording, topographic analysis of VECP amplitudes, and MRI imaging of the orbit and cerebrum.
Results:
Best corrected visual acuity was 20/50 OD and 20/80 OS. Anterior segments did not present any abnormalities. Pupillary reactions, ocular motility and orthoptic status were normal. Funduscopic findings were: minor nasal prominence of the optic discs, relatively hypopigmented tabulated fundus, fine-structured RPE-irregularities of the fovea, and small parafoveal depigmented areas mainly in superior position. Fundus near-infrared and standard autofluorescence presented multiple intramacular hypofluorescent spots approximately 50-300 µm in diameter. These spots were transiently hyperfluorescent in angiography. In SD-OCT scans local irregularities and hyperreflective structures were identified on the level of the RPE-photoreceptor junction. The P100-latency of visual evoked potentials was 107 (OD) and 105 msec (OS). Topographic analysis of VECP amplitudes showed an atypical shift resembling findings in albino carriers. ERG a- and b-wave amplitudes were relatively high and implicit times relatively short. Nuclear magnetic resonance tomography revealed a hypolastic corpus callosum.
Conclusions:
The association of reduced visual acuity, regionally fundus hypopigmentation, and electrophysiological findings observed in this case indicate an atypical form of incomplete albinism so far not reported in Prader Willi-syndrome.
Keywords: retina • retinal pigment epithelium