Determining a Worldwide Prevalence of Oculocutaneous Albinism: A Systematic Review.

Purpose: The aim of this systematic review was to investigate the available data on the epidemiology of oculocutaneous albinism (OCA) around the world, and to determine whether a generalizable, worldwide prevalence figure could be proposed. Methods: Extensive literature search strategies were conducted, interrogating PubMed, Scopus, and Web of Science, to locate relevant literature. Ultimately 34 studies reporting original data were included for analysis. Results: Findings showed that most data were outdated, and only 6 of 34 articles (18%) were published after 2010. There were few good studies with sound methodology and large, clearly defined population samples. Only a small proportion of countries worldwide (26/193 [13%]) have produced prevalence figures for OCA. By continent, African studies were disproportionately represented (15/34 [44%]). The highest prevalence rates (range, 1 in 22 to 1 in 1300; mean, 1 in 464) were reported in population isolates. The mean prevalence from four African countries was 1 in 4264 (range, 1 in 1755 to 1 in 7900). Prevalence for three countries in Europe (mean, 1 in 12,000; range, 1 in 10,000 to 1 in 15,000) may be underestimated, as the phenotype, in fair-skinned populations, may be missed or misdiagnosed as ocular albinism or isolated visual impairment. Population rates may vary depending on local cultural factors (e.g., consanguineous matings) and may change over time. Conclusions: The prevalence of OCA varies widely between continents and population groups, and it is often influenced by local factors. It was not possible, therefore, to determine a single, generalizable worldwide prevalence rate for OCA, although continental rates for Africa and Europe are useful.

Trends in the incidence and causes of severe visual impairment and blindness in children from Israel.

PURPOSE: To describe trends in the incidence and causes of legal childhood blindness in Israel, one of the few countries worldwide that maintain a national registry of the blind. METHODS: We performed a historical cohort study of annual reports of the National Registry of the Blind (NRB) between 1999 and 2013. All data regarding demographic information, year of registration and cause of blindness of children 0-18 years of age registered for blind certification were obtained from the annual reports of the NRB. Causes of legal blindness analyzed were optic atrophy, retinitis pigmentosa, retinopathy of prematurity (ROP), albinism, other retinal disorders, cataract, and glaucoma. The main outcome measure was the incidence of new cases of certified legal blindness. RESULTS: The incidence of newly registered legally blind children in Israel almost halved from 7.7 per 100,000 in 1999 to 3.1 per 100,000 in 2013. The decline was mainly attributable to a decreased incidence of blindness resulting from retinitis pigmentosa and ROP. The incidence of registered cases due to cerebral visual impairment increased. CONCLUSIONS: During the past decade the incidence of severe childhood visual impairment and blindness declined in Israel. A continuous decline in consanguineous marriages among the Jewish and Arab populations in Israel may have contributed to the decrease in the rate of vision loss due to retinitis pigmentosa in children.

Albinism: particular attention to the ocular motor system.

The purpose of this report is to summarize an understanding of the ocular motor system in patients with albinism. Other than the association of vertical eccentric gaze null positions and asymmetric, (a) periodic alternating nystagmus in a large percentage of patients, the ocular motor system in human albinism does not contain unique pathology, rather has "typical" types of infantile ocular oscillations and binocular disorders. Both the ocular motor and afferent visual system are affected to varying degrees in patients with albinism, thus, combined treatment of both systems will maximize visual function.

Comparison of clinical findings in pediatric patients with albinism and different amplitudes of nystagmus.

INTRODUCTION: Visual acuity in albinism can vary and is difficult to predict. We undertook this study to investigate whether patients with albinism with absent or minimal nystagmus have better visual acuity and ocular alignment than patients with albinism and obvious nystagmus. METHODS: Our retrospective chart review of 38 pediatric patients with albinism yielded 16 patients with absent or minimal nystagmus and 22 patients with obvious nystagmus. RESULTS: Patients with albinism and absent or minimal nystagmus had best-corrected visual acuities ranging from 20/20 to 20/50, with a mean visual acuity of 20/33. Those patients with albinism and obvious nystagmus had best-corrected visual acuities ranging from 20/30 to 20/200, with a mean visual acuity of 20/80. Visual acuity was significantly better in the group with absent or minimal nystagmus (P < 0.001). Of the 16 patients with absent or minimal nystagmus, 6 were orthophoric and 10 had a strabismic deviation of 12 prism diopters (PD) or less. None of these patients required strabismus surgery. Of the 22 patients with nystagmus, 16 were orthophoric, 1 had a horizontal deviation of less than 12 PD, and 5 had larger angle horizontal deviations ranging from 20 to 50 PD. CONCLUSION: Our findings suggest that pediatric albinism patients with absent or minimal nystagmus can be expected to demonstrate better visual acuity and are less likely to show a strabismic deviation of greater than 12 PD compared with those with obvious nystagmus (P = 0.0003).

Subnormal visual acuity (SVAS) and albinism in Mexican 12-13-year-old children.

BACKGROUND: In a previous study the vision of 1046 12-13-year-olds in Sweden was examined. Of those 67 had some kind of visual disturbances and in 20 no obvious cause was found. In this group, defined as children with subnormal visual acuity syndromes (SVAS), albinism was shown to be a major cause to the visual dysfunction giving a prevalence of about 1%. This is about 100 times higher than previous figures. Albinism can therefore be the cause in many cases of unexplained low visual acuity, at least in Sweden. Subnormal visual acuity is usually found in 2-4% in a pediatric population and is often called 'amblyopia'. The Swedish study showed that in many cases 'amblyopia' should be replaced by 'SVAS' and further investigation. The present Mexican study was designed identically to the Swedish study. The objective was to describe the distribution of visual acuity and the prevalence of ocular disorders, including incidence of subnormal visual acuity (SVAS) and the occurrence of albinism in a Mexican population of 12-13-year-olds. SUBJECTS AND METHODS: Altogether 1035 children, 12-13 years of age, were examined. A total number of 344 children were referred to the university pediatric eye clinic for further examination. 272 of these had simple refractive errors, 59 were diagnosed with an ophthalmological disorder and 13 children could not be pathologically classified. These were referred to a second ophthalmological examination, including VEP (Visual Evoked Potential) recordings. VEP reveals an asymmetric (right vs. left) cortical response after monocular stimulation in albinism. RESULTS: No child showed iris translucency or any other typical albinoic sign. VEP was recorded from 11 children. Three children showed an asymmetric VEP and were classified as albinos. The VEP response was normal in 8 of the children. CONCLUSIONS: The results indicate that albinism is common in Mexico, although not as common as in a similar Swedish population. A prevalence of albinism of approximately 0.3% was found in the Mexican population, compared to approximately 1% in the Swedish study group. The number of albinos was much higher in both study groups than to be expected from previous estimates. The difference between the Swedish and the Mexican figures may be explained by the general difference in pigmentation between Sweden and Mexico and thus probably by the subsequent lower number of commonly occurring albino foci in the Mexican heritage. It is emphasised that in investigations of children with SVAS, also in countries with a generally high pigmentation level, electro-physiological examinations are important, to be able to reveal albinism, but also to exclude or verify other conditions in the SVAS group, for example neurometabolic conditions.

Visual acuity, amblyopia, and ocular pathology in 12- to 13-year-old children in Northern Mexico.

PURPOSE: The aim of this study was to establish visual acuity (VA) and the prevalence of amblyopia and other ocular disorders in a population of 12- to 13-year-old children in Mexico who have not been vision screened. METHODS: A total of 1,035 12- to 13-year-old children were examined in a field study. The examination included VA, stereopsis, cover testing, refractive retinoscopy, and examination of the red reflex and posterior pole. In cases with unexplained subnormal VA, visually evoked potential/visually evoked response was also performed. RESULTS: A >or=20/20 in at least one eye was found in 93% of the subjects. Bilateral VA

Subnormal visual acuity syndromes (SVAS): albinism in Swedish 12-13-year-old children.

BACKGROUND: The vision of 12-13-year-olds in Sweden was examined in a field study. The study was designed as being a part of a large European-Latin American study, the DESAMI project. The objective was to evaluate the prevalence of residual amblyopia and ocular disorders, atiologies of subnormal vision and some normal visual parameters in this group of children. The children had to be born in Sweden in 1985 in order to have the opportunity to be included in the voluntary screening visual examinations. The full results of the study will be presented elsewhere. This paper presents clinical and VEP data of those children who had visual acuity of 0.8 or below in one or both eyes which could not be increased with glasses, or other visual/eye disturbances not explained as common amblyopia, i.e., subnormal visual acuity or pathological visual states of unknown cause, SVAS (subnormal visual acuity syndromes). SUBJECTS AND METHODS: In all, 1046 children were examined: 76 had visual disturbances of such severity that they were referred to a paediatric ophthalmologist (AS). Eighteen children could not be pathologically classified, and they were referred to another ophthalmological examination and VEP (visual evoked potential) recordings. VEP reveals an asymmetric response after monocular stimulation in albinism. RESULTS: Twelve children turned up for a second examination and VEP was recorded from 10 children. Nine children showed iris translucency. Seven children showed an asymmetric VEP and were classified as albinos. The albinoic VEPs could be subdivided into two types, (1) including all parts of the response and (2) partly excluding the P1/P100 potential complex. The VEP response was normal, showing symmetry and no other abnormality, in three of the children. CONCLUSIONS: The results indicate that albinism is common in Sweden. A prevalence value of approximately 1% is about 100 times higher than previous figures. This high prevalence may indicate another form of heredity, with genetical contribution to albinism from a varying number of albino genes and varying expression in the phenotypes, in the Scandinavian population. It is emphasised that in investigations of children with SVAS, electrophysiological examinations are important, not only to reveal albinism but also to exclude or verify neurometabolic conditions, for example.

Subnormal visual acuity syndromes (SVAS): albinism in Swedish 12-13-year-old children.

BACKGROUND: The vision of 12-13-year-olds in Sweden was examined in a field study. The study was designed as being a part of a large European-Latin American study, the DESAMI project. The objective was to evaluate the prevalence of residual amblyopia and ocular disorders, aetiologies of subnormal vision and some normal visual parameters in this group of children. The children had to be born in Sweden in 1985 in order to have the opportunity to be included in the voluntary screening visual examinations. The full results of the study will be presented elsewhere. This paper presents clinical and VEP data of those children who had visual acuity of 0.8 or below in one or both eyes which could not be increased with glasses, or other visual/eye disturbances not explained as common amblyopia, i.e., subnormal visual acuity or pathological visual states of unknown cause, SVAS (subnormal visual acuity syndromes). SUBJECTS AND METHODS: In all, 1046 children were examined: 76 had visual disturbances of such severity that they were referred to a paediatric ophthalmologist (AS). Eighteen children could not be pathologically classified, and they were referred to another ophthalmological examination and VEP (visual evoked potential) recordings. VEP reveals an asymmetric response after monocular stimulation in albinism. RESULTS: Twelve children turned up for a second examination and VEP was recorded from 10 children. Nine children showed iris translucency. Seven children showed an asymmetric VEP and were classified as albinos. The albinoic VEPs could be subdivided into two types, (1) including all parts of the response and (2) partly excluding the P1/P100 potential complex. The VEP response was normal, showing symmetry and no other abnormality, in three of the children. CONCLUSIONS: The results indicate that albinism is common in Sweden. A prevalence value of approximately 1% is about 100 times higher than previous figures. This high prevalence may indicate another form of heredity, with genetical contribution to albinism from a varying number of albino genes and varying expression in the phenotypes, in the Scandinavian population. It is emphasised that in investigations of children with SVAS, electrophysiological examinations are important, not only to reveal albinism but also to exclude or verify neurometabolic conditions, for example.

[Visual problems in albinos: a hospital study carried out at the Douala General Hospital]. / Les troubles visuels de l'albinos. Etude hospitalière réalisée à l'Hôpital général de Douala.

We report here a clinical study investigating the main visual problems associated with albinism, with a view to determining the best treatment. We came across 42 cases of albinism during the course of this study, corresponding to a prevalence for albinism of 0.15%. One in ten albinos were of the yellow mutant type and more of the albinos were men than were women (sex ratio 1.21). The maximum visual acuity recorded was 3/10 and 40.47% of the patient had a best visual acuity score no higher than 1/10. Vision was best in the yellow mutants and it improved with age. We found that 33.33% of the albino patients had a squint and 35.71% had torticullis at primary fixation. In contrast to the results of previous studies, the most common ametropia was myopic astigmatism (61.9%). These findings have potential implications for the treatment of visual problems in albinos.

X-linked ocular albinism: prevalence and mutations--a national study.

In a national retrospective register study 112 patients with ocular albinism (OA) were identified, including 60 male patients with proven or presumed X-linked ocular albinism (XLOA). Based on the birth year cohorts 1960-1989, an XLOA point prevalence at birth of 1 in 60,000 live-born was calculated. We identified 14 XLOA families in the Danish population, and obtained DNA from affected persons in nine families. Mutation analysis of the OA1 gene demonstrated seven presumed pathogenic mutations in the nine families with XLOA: five single nucleotide substitutions predicting a change of conserved amino acids (G35D, L39R, D78V, W133R and E233K) when compared with the mouse OA1 homologue, one deletion leading to the skipping of exon 2, and one single nucleotide substitution expected to affect the 5' splice site of intron 2 were found. Subsequent genealogical investigations in the three families harbouring the same mutation disclosed that two of the three pedigrees belonged to the same family. All mutations predict crucial changes in the protein structure. Clinical examination failed to identify any phenotype-genotype pattern except a milder phenotype devoid of iris translucency in the patient with the 5'splice site mutation of intron 2.

Albinism and Hermansky-Pudlak syndrome in Puerto Rico.

Five types of oculocutaneous albinism and two types of ocular albinism were found among 349 Puerto Rican albinos. The most prevalent type of albinism was the Hermansky-Pudlak syndrome (HPS). HPS was observed in five of every six albinos in Puerto Rico. The prevalence of HPS was highest in the northwestern quarter of the island, affecting approximately one in 1,800 persons, and approximately one in 22 are carriers of the gene. HPS is an autosomal recessively inherited triad of a tyrosinase-positive type of albinism, a hemorrhagic diathesis due to storage pool deficient platelets and accumulation of ceroid in tissues. The pigmentary phenotype of HPS albinos resembled that of any other type of oculocutaneous or ocular albinism. The most reliable method of diagnosing HPS is by a deficiency of platelet dense bodies observed by electron microscopy. The accumulation of ceroid in the tissues is associated with fibrotic restrictive lung disease and granulomatous enteropathic disease. The enteropathic disorder resembles Crohn's disease and with few exceptions, had its onset after 13 years of age. The major causes of death were fibrotic restrictive pulmonary disease, hemorrhagic episodes and sequelae of granulomatous enteropathic disease. Menometrorrhagia was common in women with HPS. No immune deficiency was found in HPS patients. The majority of patients with HPS had visual acuities of 20/200 or worse and consequently were legally blind. Albinos of all types, including HPS, lacked binocular vision due to nearly complete crossing of the optic tracts.

Albinism and Hermansky-Pudlak syndrome in Puerto Rico

Five types of oculocutaneous albinism and two types of ocular albinism were found among 349 Puerto Rican albinos. The most prevalent type of albinism was the Hermansky-Pudlak syndrome (HPS). HPS was observed in five of every six albinos in Puerto Rico. The prevalence of HPS was highest in the northwestern quarter of the island, affecting approximately one in 1,800 persons, and approximately one in 22 are carriers of the gene. HPS is an autosomal recessively inherited triad of a tyrosinase-positive type of albinism, a hemorrhagic diathesis due to storage pool deficient platelets and accumulation of ceroid in tissues. The pigmentary phenotype of HPS albinos resembled that of any other type of oculocutaneous or ocular albinism. The most reliable method of diagnosing HPS is by a deficiency of platelet dense bodies observed by electron microscopy. The accumulation of ceroid in the tissues is associated with fibrotic restrictive lung disease and granulomatous enteropathic disease. The enteropathic disorder resembles Crohn's disease and with few exceptions, had its onset after 13 years of age. The major causes of death were fibrotic restrictive pulmonary disease, hemorrhagic episodes and sequelae of granulomatous enteropathic disease. Menometrorrhagia was common in women with HPS. No immune deficiency was found in HPS patients. The majority of patients with HPS had visal acuities of 20/200 or worse and consequently were legally blind. Albinos of all types, including HPS, lacked binocular...