This is an 13 year old girl with 20/40 vision OD.
Questions and Answers
1. What is the most likely diagnosis? Answer: Given the classic appearance of a disrupted "egg-yolk" like lesion in the macula, the most likely diagnosis is Best's disease.
2. What are the four stages that describe the natural history of this disease and to which stage does this patient belong? Answer: First stage: previtelliform stage, characterized by a normal fundus appearance. Second stage: vitelliform stage, characterized by a well-circumscribed yellow-lesion that looks like the "egg-yolk", that appears to be located under the pigment epithelium. Third stage: disruption in the "egg-yolk" and the yellow material can accumulate inferiorly in the macula in the subretinal space to give a "pseudohypopyon appearance". Fourth stage: yellow deposits are scattered throughout the posterior pole, giving a scrambled egg appearance. The appearance of the fundus photo in this quiz is consistent with the third stage, characterized by the pseudohypopyon.
3. What makes up the "egg-yolk"? Answer: It is thought to be an excessive amount of lipofuscin -like material in RPE.
4. What is the inheritance pattern? Answer: This disease is inherited in autosomal dominat pattern. It is usually manifested in childhood or early adolescence.
5. How is the diagnosis made? Answer: The EOG is abnormal in affected patients. If the fundus appearance is consistent with one of the four stages and the EOG ratio less than or equal to 1.5, one can make the diagnosis of Best's disease. The full ERG is typically normal, but the foveal ERG may be abnormal. Asymptomatic obligate carriers also have abnormal EOGs.
6. What is the visual prognosis for this condition? Answer: Initially the vision is normal. According to Mohler and Fine (Ophthalmol. 1981) the prognosis is good for retaining useful vision in at least one eye throughout life in patients with Best's disease. Eight-eight percent of patients will have better than 20/40 vision in their better eye. Only 4 % of patients will have vision less than 20/200 in their better eye.