The “Best” masquerader

A 24-year-old male presented with defective vision in both eyes (OU) for 1 year. The family history was negative. The best-corrected visual acuity was 6/12 N6 in the right eye (OD) and 6/18 N8 in the left eye (OS). Fundus examination in OU revealed multifocal vitelliform lesions around the vascular arcades (symmetric), with neurosensory detachment [Fig. 1 a and b]. OD showed a small subfoveal yellow deposit [Fig. 1a]. Swept-source optical coherence tomography showed a subfoveal drusen-like deposit in OD, subretinal fluid, and outer retinal layer thickening in OU [Fig. 1c and d]. Fundus blue autofluorescence (FAF) revealed bilateral hyper-autofluorescent spots corresponding to the multifocal vitelliform lesions [Fig. 1e and f].Figure 1: (a and b) Represent color fundus photos showing multifocal vitelliform lesions, RPE mottling due to chronic subretinal fluid (SRF) in both eyes (OU), and subfoveal vitelliform deposit in the right eye (OD) (a). (c and d) represent SS-OCT images showing SRF with outer retinal layer thickening and Ellipsoid Zone defects in OU with subfoveal vitelliform deposit in OD (c). (e and f) represent fundus autofluorescence images showing hyper auto-fluorescence corresponding to vitelliform lesionsWhat is your next step for the left eye? Fundus fluorescein angiography (FFA) followed by a focal laser to the leaks. Oral Eplerenone 25 mg BD for 3 months. Electrooculogram (EOG). Anti-VEGF injection in both eyes. Findings The electrooculogram shows a decreased light peak with a reduced Arden's ratio of 1:21 in OD and 1:15 in OS [Fig. 2]. FFA was done to rule out choroidal neovascular membrane (CNV), which showed no leaks/CNV but non-specific hyperfluorescent spots corresponding to long-standing neurosensory detachment [Fig. 2 a and b]. The presence of subretinal fluid with bilateral and symmetrical multifocal vitelliform lesions around the vascular arcades with an abnormal EOG is consistent with the diagnosis of autosomal recessive bestrophinopathy (ARB). Genetic testing was suggested.Figure 2: (a and b) Represent an electrooculogram report showing a reduced light peak in OU. (c and d) depict FFA images showing no leaks/CNV but non-specific hyperfluorescent spots due to long-standing neurosensory detachmentDiagnosis Autosomal recessive bestrophinopathy (ARB). Correct answer C. Electrooculogram (EOG) Discussion ARB is caused by biallelic mutations of the BEST1 gene.[1-3] These patients have more profound central vision loss with more widespread funduscopic changes than autosomal dominant best dystrophy.[2] Typically, multiple punctate yellow dots/flecks around vascular arcades are seen with subretinal fluid at the macula and an abnormal EOG.[1-3] Other features include high hyperopia, shallow anterior segment, angle-closure glaucoma, retinoschisis, and thickened choroid.[1-3] It is often misdiagnosed as central serous chorioretinopathy but needs to be differentiated from the same due to differences in prognosis and management. This is done through typical clinical and FAF patterns supported by EOG and genetic testing.[1,2] The progression of visual loss in ARB is gradual, with CNV being a significant cause of visual impairment.[3] Declaration of patient consent The authors certify that they have obtained all appropriate patient consent forms. In the form, the patient(s) has/have given his/her/their consent for his/her/their images and other clinical information to be reported in the journal. The patients understand that their names and initials will not be published and due efforts will be made to conceal their identity, but anonymity cannot be guaranteed. Financial support and sponsorship: Nil. Conflicts of interest: There are no conflicts of interest.