2.9 Nettleship-Falls X-Linked Ocular Albinism 87
Nettleship-Falls ocular albinism is an X-linked recessively inherited retinal disease character- ized by reduced visual acuity, translucent irides, congenital nystagmus, photophobia, hypopig- mentation of the fundi, and foveal dysplasia (Fig. 2.49) [1, 2]. Full-field ERGs and EOGs are normal (Fig. 2.50), and focal macular ERGs are moderately reduced because of the foveal dys- plasia (Fig. 2.51).
Histopathological examination of the retina has revealed evidence of foveomacular dyspla- sia [3], including absence of a foveal pit, which can also be detected by OCT (Fig. 2.52).
The ganglion cell layer is present throughout the macula and resembles that seen in the parafoveal area of normal subjects.
In a variant of X-linked ocular albinism in Black and Japanese men, the transillumination defect of the iris and the characteristic fundus hypopigmentation may not be present as shown in Fig. 2.49. Visual acuity may be better than that in typical X-linked ocular albinism. In such cases, the diagnosis may require skin biopsy. However, it should be noted that asymp- tomatic female carriers of these mutations always show streaky and mottled RPE ophthal- moscopically, which is of diagnostic value (Fig.
2.53) [2]. The full-field ERGs and the focal macular ERG and OCT are normal in the female carriers.
2.9 Nettleship-Falls X-Linked Ocular Albinism
Fig. 2.49. Iris hypopigmentation (left) and fundus photograph (right) from a 35-year-old male patient with Nettleship-Falls ocular albinism. The visual acuity was 0.4
RDI2(104%) 9/9/05 7:52 PM Page 87
88 2 Hereditary Retinal and Allied Diseases
Fig. 2.50. Full-field ERGs from a normal control and the patient whose fundus is shown in Fig. 2.49
Fig. 2.51. Focal macular ERGs elicited by 5° and 10° spots from a normal control and the patient shown in Fig. 2.49
Fig. 2.52. OCT of a patient with Nettleship-Falls ocular albinism. A ganglion cell layer is present throughout the macula and resembles that seen in the perifoveal area of normal individuals
RDI2(104%) 9/9/05 7:52 PM Page 88
2.9 Nettleship-Falls X-Linked Ocular Albinism 89
References
1. Nettleship E (1909) On some hereditary diseases of the eye. Trans Ophthalmol Soc UK 29:LVII–
CXCVIII
2. Falls HF (1951) Sex-linked ocular albinism display- ing typical fundus changes in the female heterozy- gote. Am J Ophthalmol 34(Pt 2):41–50
3. Garner A, Jay BS (1980) Macromelanosomes in X- linked ocular albinism. Histopathology 4:243–254 Fig. 2.53. Fundi of four female carriers of Nettleship-Falls ocular albinism, showing streaky and mottled retinal pigment epithelium
RDI2(104%) 9/9/05 7:53 PM Page 89
