Normal electro-oculography in a young Omani male with genetically confirmed best disease complicated by choroidal neovascularization

Abstract

Best vitelliform macular dystrophy (VMD) is an autosomal dominant macular dystrophy caused by heterozygous mutations in the bestrophin1 gene. Patients with this condition typically have an abnormal electrooculogram. We report a case of a 16-year-old male who presented with gradual progressive vision loss in the right eye. Ophthalmic assessment included funduscopy, optical coherence tomography (OCT), fluorescein angiography, electro-oculography, electroretinography, and genetic testing. Visual acuity was 20/500 and 20/20 in the right and left eyes, respectively. Ophthalmoscopy revealed round yellow lesions in both foveae similar to what is typically seen in Best disease. A subretinal hemorrhage surrounding the right foveal lesion was also noted. OCT demonstrated an elevated neurosensory retina with a subretinal lesion in the right macula. Fluorescein angiography of the right eye confirmed the presence of choroidal neovascularization. Genetic analysis of VMD2/BEST1 sequences confirmed the diagnosis of Best disease. However, contrary to what was expected, the patient's electro-oculography was normal. The findings of this case support a small number of previous reports demonstrating cases of Best disease with normal electro-oculography. While an abnormal electro-oculography along with the typical features of Best disease confirms the diagnosis, a normal result may not exclude the diagnosis. Genetic testing is probably the most important test for establishing the diagnosis of Best disease.

Keywords: Anti-vascular endothelial growth factor; best disease; choroidal neovascularization; electrooculography; vitelliform macular dystrophy.

Figure 1

Family pedigree of the patient

Figure 2

Fundus photograph of a yellow lesion in the macula with subretinal hemorrhage (a). A similar but smaller lesion with no hemorrhage was found in the left macula (b). FFA of the right fundus (c) showed a central hyperfluorescent area (leakage) surrounded by well-circumscribed hypofluorescence (blockage), consistent with choroidal neovascularization. FFA of the left fundus was unremarkable (d)

Figure 3

Optical coherence tomography of the right macula (a) showing elevated neurosensory retina with an underlying hyper-reflective lesion and sub retinal fluid. A smaller hyper-reflective subfoveal lesion was revealed on left eye optical coherence tomography (b)

Figure 4

Pattern electroretinogram showing marked reduction in P50 (arrow head) and N95 (arrow) waves amplitude in the right eye and normal waves in the left eye. This indicates a severe macular dysfunction in the right eye

Figure 5

Electro-oculogram from both eyes showing normal peak/trough (Arden) ratio in both eyes. Right eye 3.08; Left eye 3.66 (normal >1.8–2)