From strabismus to pseudo-strabismus and familial exudative vitreoretinopathy, a clinical journey of phenotypically identic twins with symmetric ocular features

Abstract

Familial Exudative Vitreoretinopathy (FEVR) is a rare genetic condition and several genes have been identified.
Clinically, it can cause macular dragging and therefore pseudo-strabismus or exudative or tractional retinal
detachment leading to loss of vision in severe cases. Other symptoms including refractive error, cataract and
glaucoma have been documented. The main differential diagnosis remains retinopathy of prematurity. We
report two phenotypically identic twins that were seen in a lower level hospital and diagnosed with strabismus
presumed to be secondary to myopia. A multidisciplinary team including optometrist, paediatric and vitreoretinal
ophthalmologists re-examined the twins and found eccentric fixation and features of FEVR on fundoscopy
and angiography. There was a high chance that the twins would have been managed only with spectacles
missing the opportunity to be followed up for a more severe vitreoretinal proliferative disease. This case report
underlines the genetic basis of the disease with symmetrical and equally distributed myopia, macular dragging
and subsequent pseudo-strabismus and FEVR angiographic features. A multidisciplinary team-work was of
utmost importance. Beside refractive error correction, the twins also benefited from laser photocoagulation to
the avascular retinae to prevent further progress of the proliferative vitreoretinopathy. A good clinical history is
enough to rule out retinopathy of prematurity and focus on other causes of retinal fibrovascular membranes in
the pediatric population. The fluorescein angiography can be decisive in the clinical setting while genotyping is
essential for genetic counseling. Clinicians in low income countries may depend solely on a good clinical history
and examination but a high index of suspicion in presence of clinical features of FEVR is key.