2.21 Best’s Disease 165
Best’s disease (vitelliform macular dystrophy) is an autosomal dominant, pleomorphic, pro- gressive disease of the RPE with an onset early in life [1]. The unique fundus appearance (Fig.
2.143) is used to classify the stages: previtelli- form, vitelliform, pseudohypopyon, vitellirup- tive, and atrophic [2]. The OCT images show a solid substance underneath the RPE in the macula (Fig. 2.143). The visual prognosis is rel- atively good, and most patients retain reading vision in at least one eye throughout life. The progression of the visual acuity reduction is slow and begins for the most part after the age of 40 years [3].
The full-field ERGs are normal at all stages [4], but as shown in Fig. 2.144, the focal macular ERGs are slightly to moderately reduced, indicating that only the macula is affected.
However, as shown in Fig. 2.145, the EOG is markedly abnormal, with the light-to-dark ratio usually less than 1.50 [5]. The EOG ratios of the carriers of the disease are also usually subnormal [5]. In 1998 a mutation of the VMD2 gene was identified as causing Best’s vitelliform macular dystrophy [6].
Adult-onset foveomacular vitelliform dys- trophy [7] may show similar ophthalmoscopic findings in the macula. The lesion is symmetri-
2.21 Best’s Disease
Fig. 2.143. Fundi of patients with Best’s disease at various stages. A Vitelliform. B Pseudohypopyon. C Scrambled egg.
D Atrophic. E OCT image RDI2(104%) 9/9/05 8:22 PM Page 165
166 2 Hereditary Retinal and Allied Diseases
cal, solitary, usually one-third to one disk diam- eter in size, round or oval, slightly elevated, yel- lowish, and subretinal. There is often a central pigmented spot in each eye (Fig. 2.146). The patients may be visually asymptomatic or have mild visual blurring and metamorphopsia in
one or both eyes, usually with an onset between ages 30 and 50 years. The full-field ERGs and EOGs are essentially normal. The normal EOG is a key differential point between Best disease and adult-onset foveomacular vitelliform dys- trophy.
Fig. 2.144. Focal macular ERGs elicited by 5°, 10°, and 15° spots recorded from a normal control and patients at various stages of Best’s disease. (From Kondo et al. [4])
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2.21 Best’s Disease 167
References
1. Best F (1905) Uber eine hereditare Maculaaffection:
Beitrag zur Vererbungslehre. Z Augenheilkd 13:
199–212
2. Gass JDM (1977) Stereoscopic atlas of macular dis- eases; diagnosis and treatment, 2nd edn. Mosby, St.
Louis, p 162
3. Fishman GA, Baca W, Alexander KR (1993) Visual acuity in patients with Best vitelliform macular dystrophy. Ophthalmology 100:1665–1670
4. Kondo M, Kondo N, Tanikawa A, Horiguchi M, Miyake Y, Awaya S (1997) Clin Rev Ophthalmol Jpn 91:313–317
5. Deutman AF (1969) Electro-oculogram in families with vitelliform dystrophy of the fovea: detection of the carrier state. Arch Ophthalmol 81:305–311 6. Marquardt A (1998) Mutations in a novel gene,
VMD2, encoding a protein of unknown properties cause juvenile-onset vitelliform macular dystrophy (Best disease). Hum Mol Genet 7:1517–1525 7. Bloom LH, Swanson DE, Bird AC (1981) Adult
vitelliform macular degeneration. Br J Ophthalmol 65:800–801
Fig. 2.145. Electrooculography of a normal control (filled circles) and a patient with Best’s disease (open circles)
Fig. 2.146. Fundus of a 48-year-old man with adult-onset foveomacular vitel- liform dystrophy. Visual acuity was 0.5 in both eyes, and EOG was normal. No family history was detected
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