A comprehensive monocentric ophthalmic study with Gaucher disease type 3 patients: vitreoretinal lesions, retinal atrophy and characterization of abnormal saccades.

Background: The differentiation between Gaucher disease type 3 (GD3) and type 1 is challenging because pathognomonic neurologic symptoms may be subtle and develop at late stages. The ophthalmologist plays a crucial role in identifying the typical impairment of horizontal saccadic eye movements, followed by vertical ones. Little is known about further ocular involvement. The aim of this monocentric cohort study is to comprehensively describe the ophthalmological features of Gaucher disease type 3. We suggest recommendations for a set of useful ophthalmologic investigations for diagnosis and follow up and for saccadometry parameters enabling a correlation to disease severity.

Methods: Sixteen patients with biochemically and genetically diagnosed GD3 completed ophthalmologic examination including optical coherence tomography (OCT), clinical oculomotor assessment and saccadometry by infrared based video-oculography. Saccadic peak velocity, gain and latency were compared to 100 healthy controls, using parametric tests. Correlations between saccadic assessment and clinical parameters were calculated.

Results: Peripapillary subretinal drusen-like deposits with retinal atrophy (2/16), preretinal opacities of the vitreous (4/16) and increased retinal vessel tortuosity (3/16) were found. Oculomotor pathology with clinically slowed saccades was more frequent horizontally (15/16) than vertically (12/16). Saccadometry revealed slowed peak velocity compared to 100 controls (most evident horizontally and downwards). Saccades were delayed and hypometric. Best correlating with SARA (scale for the assessment and rating of ataxia), disease duration, mSST (modified Severity Scoring Tool) and reduced IQ was peak velocity (both up- and downwards). Motility restriction occurred in 8/16 patients affecting horizontal eye movements, while vertical motility restriction was seen less frequently. Impaired abduction presented with esophoria or esotropia, the latter in combination with reduced stereopsis.

Conclusions: Vitreoretinal lesions may occur in 25% of Gaucher type 3 patients, while we additionally observed subretinal lesions with retinal atrophy in advanced disease stages. Vertical saccadic peak velocity seems the most promising "biomarker" for neuropathic manifestation for future longitudinal studies, as it correlates best with other neurologic symptoms. Apart from the well documented abduction deficit in Gaucher type 3 we were able to demonstrate motility impairment in all directions of gaze.