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Editor,—Recently, the association of Best‘s vitelliform macular dystrophy (BVMD) with mutations in chromosome 11 has been reported, and candidate genes that may be affected by these mutations have been identified.1 2 However, the role of these genes in retinal and retinal pigment epithelium (RPE) function is not clear. In addition, factors that determine the progression of the vitelliform foveal lesion leading to impairment of visual acuity in patients with BVMD are not understood. We present a case in which blunt trauma was associated with deterioration of visual acuity and macular scar formation in a patient with BVMD.
A 14 year old male presented to our clinic after being hit in his right eye by a fist 40 days earlier. He complained of reduced visual acuity in this eye since the trauma. He had a history of good and equal visual acuity in both eyes until the trauma occurred, and ocular and systemic history were unremarkable. He was the fourth son among eight children (two males and six females), and the patient was unaware of any significant ocular diseases in his family. Other family members were not available for our examination.
Best corrected visual acuity was 6/24 and 6/7.5 in the right and left eye respectively. Anterior segments and intraocular pressures were normal. Funduscopy of the right eye revealed a foveal scar with remnants of subretinal haemorrhage around the fovea. Yellowish subretinal material was seen extending centrally from the lower temporal arcade. In this area, two parallel pigmented lines that may represent choroidal ruptures were noted (Fig 1A). The left eye showed a vitelliform foveal lesion (Fig 1B). The optic disc and peripheral retina were normal in both eyes.
ISCEV standard electro-oculography (EOG) and electroretinography (ERG) were performed. The EOG showed severely reduced light peak to dark trough ratios of 120% and 100% in the right and left eye, respectively (lower limit of normal 180%). The full field photopic cone ERG response, as well as the scotopic rod and mixed cone-rod responses, were normal. The patient could not discriminate the colours on the Farnsworth D-15 test in his right eye, while the left eye showed a deuteranopic defect.
On the basis of these findings, we diagnosed blunt trauma that resulted in subretinal haemorrhage and foveal scar formation in a patient with BVMD. On follow up examination 1 month later, the visual acuity remained unchanged. However, the haemorrhage surrounding the foveal scar as well as the yellowish subretinal material in the posterior pole of the right eye had absorbed, and mild RPE changes were noted (Fig1C). Fluorescein angiography at this time showed staining of the foveal scar in the right eye with hypofluoresence in the area where the subretinal material was previously present (Fig 2A). In the left eye, early hypofluoresence and late staining of the foveal vitelliform lesion were seen (Fig 2B).
Submacular haemorrhage has been previously reported in several cases of BVMD during the natural course of the disease.3 In addition, Benson et al reported in 1975 a single case of a child with BVMD who had blunt trauma complicated by rupture of the vitelliform lesion, subretinal haemorrhage, scarring of the fovea, and severe reduction of visual acuity.4 In an attempt to explain the occurrence of such haemorrhages in BVMD, it was suggested that a metabolic abnormality causes the retinal pigment epithelium and Bruch’s membrane in these patients to be especially vulnerable to rupture, with resultant subretinal bleeding from the choriocapillaris.5 Interestingly, one of the recently identified candidate genes for BVMD is indeed expressed in the RPE.2
Our patient had the typical clinical and electrophysiological findings of BVMD. His visual acuity deteriorated in one eye after he suffered blunt trauma that resulted in damage to the retinal pigment epithelium and Bruch's membrane, as evidenced by subretinal bleeding and scarring of the fovea. The yellowish subretinal material that was later absorbed may also represent remnants of de-haemoglobinised subretinal haemorrhage (the patient was first examined 40 days after the trauma). Alternatively, this yellowish material may have originated from the vitelliform lesion ruptured by the trauma. The visual acuity deteriorated following this rupture with formation of a fibrous foveal scar.
The present case and the case reported by Benson et al demonstrate that the consequences of blunt trauma in BVMD can be devastating. Vitelliform lesion disruption, haemorrhage and, perhaps, choroidal ruptures can occur, with loss of central visual acuity that may have otherwise persisted for many years. Therefore, it is important to warn patients with BVMD about their vulnerability to trauma and furthermore, as Benson has indicated,4 patients should be advised to use protective eyewear, at least when participating in sports or other high impact activities.