Visual loss and foveal lesions in Usher's syndrome

The Impact of Retinitis Pigmentosa on Young Adults: Psychological, Educational, Vocational and Social Considerations

Retinitis pigmentosa (RP) refers to a group of inherited retinal degenerative disorders in which night and peripheral vision are gradually lost. A national sample of young adults with RP reveals that a significant number feel that RP adversely affects their education, employment, mobility and socialization. Participants feel that special counseling is needed to accept and adjust to their condition, and that sharing with peers would be beneficial.

Considerations in Diagnosing Usher's Syndrome: RP and Hearing Loss

The association of hearing loss and retinitis pigmentosa has been generally recognized as Usher's Syndrome, although variations in the syndrome have not been clearly delineated. The diagnosis of a progressive visual disease in a person with severe hearing impairment has devastating implications for the individual's future. This article reviews findings of this syndrome and suggests strategies for dealing with some of the clinical problems displayed by Ushers Syndrome patients.

Usher Syndrome and Color Vision

PURPOSE

The aim of this study is to report on the results of color vision testing in a European cohort of patients with Usher syndrome (USH). We describe the results in relation to Usher type (USH1 and USH2), age and visual acuity.

METHODS AND METHODS

The color vision of 220 genetically confirmed adult USH patients, aged 18-70 years, was analyzed with one of three methods: the Farnsworth D-15 Dichotomous test (D-15) along with the Lanthony desaturated 15 Hue tests (D-15d), the Roth 28-Hue test, or the Ishihara 14-plate test. Visual acuity was measured with either the ETDRS or the SNELLEN charts. The Confusion index, the Selectivity index and the Confusion angle were calculated for the panel tests and used for analysis. The numbers of plates that could not be read were analyzed for the Ishihara test.

RESULTS

For the panel tests, the degree of color loss (Confusion index) is similar in both subtypes of USH, but the polarization of error scores (Selectivity index) is significantly lower in USH1 than USH2, showing more diffuse errors than those found in USH2. There is no significant correlation between logMAR visual acuity and the Confusion or the Selectivity indices. Additionally, we find a significant correlation between patient age and the degree and the polarity of the loss only in USH2. There was no difference between USH1 and USH2 in the results of the Ishihara test.

CONCLUSIONS

The examination of color vision in patients with USH shows a significant difference in the pattern of color vision loss in USH1 and USH2 patients, but not in the severity of the loss. In USH2, we find a correlation between patient age and the degree and the polarity of the loss. These results may be due to differences in the pathogenesis of retinal dystrophy in USH1 and USH2.

CLINICAL PRESENTATION AND DISEASE COURSE OF USHER SYNDROME BECAUSE OF MUTATIONS IN MYO7A OR USH2A

PURPOSE

To evaluate differences in the visual phenotype and natural history of Usher syndrome caused by mutations in MYO7A or USH2A, the most commonly affected genes of Usher syndrome Type I (USH1) and Type II (USH2), respectively.

METHODS

Eighty-eight patients with a clinical diagnosis of USH1 (26 patients) or USH2 (62 patients) were retrospectively evaluated. Of these, 48 patients had 2 disease-causing mutations in MYO7A (10 USH1 patients), USH2A (33 USH2 patients), and other USH (5 patients) genes. Clinical investigation included best-corrected visual acuity, Goldmann visual field, fundus photography, electroretinography, and audiologic and vestibular assessments. Longitudinal analysis was performed over a median follow-up time of 3.5 years.

RESULTS

Patients carrying mutations in MYO7A had a younger age of onset of hearing and visual impairments than those carrying mutations in USH2A, leading to an earlier diagnosis of the disease in the former patients. Longitudinal analysis showed that visual acuity and visual field decreased more rapidly in subjects carrying MYO7A mutations than in those carrying USH2A mutations (mean annual exponential rates of decline of 3.92 vs. 3.44% and of 8.52 vs. 4.97%, respectively), and the former patients reached legal blindness on average 15 years earlier than the latter.

CONCLUSION

The current study confirmed a more severe progression of the retinal disease in USH1 patients rather than in USH2 patients. Furthermore, most visual symptoms (i.e., night blindness, visual acuity worsening) occurred at an earlier age in USH1 patients carrying mutations in MYO7A.

Novel syndrome of cataracts, retinitis pigmentosa, late onset deafness and sperm abnormalities: a new Usher syndrome subtype with X-linked inheritance?

Tissues of the auditory, ocular and reproductive systems have some similarities in their protein families and structures. Consequently, syndromes comprising these systems are described. Hearing loss alone is a component of more than 400 known syndromes and is a common nonsyndromic congenital disorder. Here we describe a syndrome in five brothers with the distinctive presentation of late-onset progressive hearing loss, cataracts, retinitis pigmentosa, sperm motility and shape problems in a family from the Kurdish population in Iran. The clinical findings of these patients are presented in detail and compared to the classical Usher syndromes.

Autosomal recessive retinitis pigmentosa with preserved para-arteriolar retinal pigment epithelium

Retinitis pigmentosa with preserved para-arteriolar retinal pigment epithelium is a rare form of retinitis pigmentosa that starts early in life with preservation of retinal pigment epithelium adjacent to and under the retinal arterioles and that has hitherto been described as an isolated form. We examined 22 patients from one large family, together with two isolated patients, and confirmed the presumed autosomal recessive mode of inheritance in this type of retinitis pigmentosa. New findings associated with retinitis pigmentosa with preserved para-arteriolar retinal pigment epithelium were asteroid hyalosis in four (17%) of 24 patients, tortuosity of retinal arterioles in 11 (46%) of 24 patients, peripheral regions of opacified vessels in eight (33%) of 24 patients, and preservation not only of the para-arteriolar pigment epithelium, but also of the peripheral retinal pigment epithelium in 13 (54%) of 24 patients. Previously reported signs present in these patients were nystagmus in six (25%) of 24 patients, hypermetropia in 23 (96%) of 24 patients, optic nerve head drusen in nine (38%) of 24 patients, vascular sheathing in 11 (46%) of 24 patients, maculopathy in all 24 patients (100%), yellow round deposits in the posterior pole in nine (38%) of 24 patients, exudates resembling those in Coats' disease in two (8%) of 24 patients, visual field defects in all 24 patients (100%), and nondeductible electroretinograms in 21 (91%) of 23 patients. Linkage analysis carried out in the large family resulted in the assignment of a gene for retinitis pigmentosa with preserved para-arteriolar retinal pigment epithelium to chromosome 1q31-q32.1.

Foveal cone pigments and sensitivity in young patients with Usher's syndrome

Psychophysical and reflection retinal densitometric techniques were used to investigate foveal function of three patients (ages 14, 16, and 19 years) with Usher's syndrome who had good central visual acuity and, by ophthalmoscopic examination, normal foveal areas. During dark adaptation foveal sensitivity and its relation to proportion of cone pigment present were normal, but the kinetics of regeneration of the pigments were markedly abnormal. Measurements were made to consider the possibilities that the disorders of regeneration were associated with altered light-catching capacities of the patients' cone pigments, deranged transport of visual cycle substances between the retinal pigment epithelium and photoreceptors, or lingering photoproducts. None of the mechanisms fully accounted for the observed kinetics. The results suggested that abnormal kinetics of regeneration are among the earliest signs of malfunction of the foveal photoreceptor-pigment epithelial complex in some of the retinal degenerative disorders.