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Indian Journal of Ophthalmology May 2023
Topics: Humans; Albinism, Ocular; Retina; Visual Acuity; Choroid; Tomography, Optical Coherence
PubMed: 37203000
DOI: 10.4103/IJO.IJO_3059_22 -
Advances in Experimental Medicine and... 2016Regulation of vesicle trafficking to lysosomes and lysosome-related organelles (LROs) as well as regulation of the size of these organelles are critical to maintain...
Regulation of vesicle trafficking to lysosomes and lysosome-related organelles (LROs) as well as regulation of the size of these organelles are critical to maintain their functions. Disruption of the lysosomal trafficking regulator (LYST) results in Chediak-Higashi syndrome (CHS), a rare autosomal recessive disorder characterized by oculocutaneous albinism, prolonged bleeding, severe immunodeficiency, recurrent bacterial infection, neurologic dysfunction and hemophagocytic lympohistiocytosis (HLH). The classic diagnostic feature of the syndrome is enlarged LROs in all cell types, including lysosomes, melanosomes, cytolytic granules and platelet dense bodies. The most striking CHS ocular pathology observed is an enlargement of melanosomes in the retinal pigment epithelium (RPE), which leads to aberrant distribution of eye pigmentation, and results in photophobia and decreased visual acuity. Understanding the molecular function of LYST and identification of its interacting partners may provide therapeutic targets for CHS and other diseases associated with the regulation of LRO size and/or vesicle trafficking, such as asthma, urticaria and Leishmania amazonensis infections.
Topics: Animals; Chediak-Higashi Syndrome; Cytoplasmic Granules; Humans; Lysosomes; Melanosomes; Organelles; Photophobia; Retinal Pigment Epithelium; Vesicular Transport Proteins; Visual Acuity
PubMed: 26427484
DOI: 10.1007/978-3-319-17121-0_99 -
Annual Review of Vision Science Nov 2015Visual defects affect a large proportion of humanity, have a significant negative impact on quality of life, and cause significant economic burden. The wide variety of...
Visual defects affect a large proportion of humanity, have a significant negative impact on quality of life, and cause significant economic burden. The wide variety of visual disorders and the large number of gene mutations responsible require a flexible animal model system to carry out research for possible causes and cures for the blinding conditions. With eyes similar to humans in structure and function, zebrafish are an important vertebrate model organism that is being used to study genetic and environmental eye diseases, including myopia, glaucoma, retinitis pigmentosa, ciliopathies, albinism, and diabetes. This review details the use of zebrafish in modeling human ocular diseases.
PubMed: 28532376
DOI: 10.1146/annurev-vision-082114-035717 -
Journal of the European Academy of... Jul 2021Albinism is a worldwide genetic disorder caused by mutations in at least 20 genes, identified to date, that affect melanin production or transport in the skin, hair and...
Albinism is a worldwide genetic disorder caused by mutations in at least 20 genes, identified to date, that affect melanin production or transport in the skin, hair and eyes. Patients present with variable degrees of diffuse muco-cutaneous and adnexal hypopigmentation, as well as ocular features including nystagmus, misrouting of optic nerves and foveal hypoplasia. Less often, albinism is associated with blood, immunological, pulmonary, digestive and/or neurological anomalies. Clinical and molecular characterizations are essential in preventing potential complications. Disease-causing mutations remain unknown for about 25% of patients with albinism. These guidelines have been developed for the diagnosis and management of syndromic and non-syndromic forms of albinism, based on a systematic review of the scientific literature. These guidelines comprise clinical and molecular characterization, diagnosis, therapeutic approach and management.
Topics: Albinism; Albinism, Oculocutaneous; Humans; Melanins; Nystagmus, Pathologic; Practice Guidelines as Topic; Systematic Reviews as Topic; Vision Disorders
PubMed: 34042219
DOI: 10.1111/jdv.17275 -
Eye (London, England) Jul 2022Visual impairment is rare but has significant impact on the neurobehavioural development and quality of life of children. This paper presents the key findings from the...
BACKGROUND
Visual impairment is rare but has significant impact on the neurobehavioural development and quality of life of children. This paper presents the key findings from the Australian Childhood Vision Impairment Register, which commenced in 2008 to report on children diagnosed with permanent visual impairment.
SUBJECTS/METHODS
Families consent to completing a data form related to their child and for contact with the child's ophthalmologist. Ophthalmologists complete and return a comprehensive data form on the child's primary and secondary ocular diagnoses, associated disabilities and health conditions, visual acuity and visual fields. Data is stored on a secure database and anonymised data is available to researchers and for planning purposes.
RESULTS
Nine-hundred four children and their families provided informed consent for participation, with 57% males and 43% females. Most children spoke English in their home. Eighty-three percent of children were born full term, with a birth weight of >2500 g (81%). Children were commonly suspected to have visual impairment by a parent, with 68% of families receiving a diagnosis of visual impairment by their child's first birthday. The most common primary diagnoses were retinal dystrophy (17%), CVI (15%) and Albinism (11%). A secondary diagnosis of infantile nystagmus occurred in 33% of children. Additional disabilities and/or developmental delay were reported for 44% of children. Corrected binocular visual acuity was reported for 75% of children, with moderate visual impairment being most common.
CONCLUSIONS
These findings contribute to knowledge of rare diseases affecting the eye and visual pathway and represent Australian childhood visual impairment.
Topics: Australia; Child; Female; Humans; Male; Quality of Life; Vision Disorders; Vision, Low; Visual Acuity
PubMed: 34193985
DOI: 10.1038/s41433-021-01656-1 -
European Journal of Human Genetics :... Nov 2023Oculocutaneous albinism is an inherited disorder of melanin biosynthesis, characterized by absent or reduced pigmentation of the skin, hair, and eyes. Molecular...
Oculocutaneous albinism is an inherited disorder of melanin biosynthesis, characterized by absent or reduced pigmentation of the skin, hair, and eyes. Molecular alterations of genes that cause non-syndromic albinism in Asian Indians are poorly characterized. This information would be useful for developing therapies for this disorder. We analyzed 164 persons with non-syndromic albinism, belonging to unrelated families from all parts of India, for molecular changes in the causative genes. Subjects with white hair, white skin, and red iris had their tyrosinase gene sequenced and were also tested by MLPA for deletions/duplications. Subjects with negative results or with darker skin, golden/brown or darker hair had sequencing of TYR, P, TYRP1, SLC45A2 and GPR143 genes. Pathogenic variants in TYR (OCA1) were observed in 139 (84.7%) patients, in the P gene (OCA2) in 20 (12.2%), in TYRP1 (OCA3) in two (1.2%), in SLC45A2 (OCA 4) in one (0.61%), and in GPR143 (X-linked ocular albinism) in two (1.2%) patients. Of 278 alleles with variants in TYR, 179 (64.3%) alleles had (p.R278*) alteration, suggesting the possibility of therapy with a stop codon readthrough molecule. We report 20 patients with 13 disease associated variants in the P gene and 18 novel pathogenic variants in TYR, P, TYRP1, SLC45A2 and GPR143 genes. The data are compared with those reported from India, Pakistan and rest of the world. The therapeutic options in albinism are briefly described, opening this field for future therapies.
PubMed: 38030918
DOI: 10.1038/s41431-023-01496-5 -
Scientific Reports Mar 2024The purpose of this paper is to expand on the phenotype of oculocutaneous albinism type 7 (OCA7). We described three patients with OCA7: two from a consanguineous family...
The purpose of this paper is to expand on the phenotype of oculocutaneous albinism type 7 (OCA7). We described three patients with OCA7: two from a consanguineous family of Kurdish origin and one patient of Dutch origin. We compared them with all patients described to date in the literature. All newly described patients had severely reduced visual acuity (VA), nystagmus, hypopigmentation of the fundus, severe foveal hypoplasia, and chiasmal misrouting. None had iris translucency. All patients had normal pigmentation of skin and hair. We found one novel mutation in the Dutch patient: c.565G > A; p.(Gly189Ser). We compared our patients to the 15 described in the literature to date. All 18 patients had substantially pigmented skin and hair, very poor VA (0.4-1.3 logMAR), nystagmus, (mild) ocular hypopigmentation, foveal hypoplasia, and misrouting. Although pigmentation levels were mildly affected in OCA7, patients had a severe ocular phenotype with VA at the poorer end of the albinism spectrum, severe foveal hypoplasia, and chiasmal misrouting. OCA7 patients had a phenotype restricted to the eyes, and similar to that of X-linked ocular albinism. We therefore propose to rename the disorder in ocular albinism type 2. Unfolding the role of LRMDA in OCA7, may bring us a step closer in identifying the responsible factors for the co-occurrence of foveal hypoplasia and misrouting.
Topics: Humans; Albinism, Ocular; Albinism, Oculocutaneous; Nystagmus, Pathologic; Hypopigmentation; Retina; Mutation; Vision Disorders
PubMed: 38555393
DOI: 10.1038/s41598-024-57969-0 -
Acta Ophthalmologica Mar 2016Many eye diseases reduce visual acuity or are associated with visual field defects. Because of the well-defined retinotopic organization of the connections of the visual... (Review)
Review
Many eye diseases reduce visual acuity or are associated with visual field defects. Because of the well-defined retinotopic organization of the connections of the visual pathways, this may affect specific parts of the visual pathways and cortex, as a result of either deprivation or transsynaptic degeneration. For this reason, over the past several years, numerous structural magnetic resonance imaging (MRI) studies have examined the association of eye diseases with pathway and brain changes. Here, we review structural MRI studies performed in human patients with the eye diseases albinism, amblyopia, hereditary retinal dystrophies, age-related macular degeneration (AMD) and glaucoma. We focus on two main questions. First, what have these studies revealed? Second, what is the potential clinical relevance of their findings? We find that all the aforementioned eye diseases are indeed associated with structural changes in the visual pathways and brain. As such changes have been described in very different eye diseases, in our view the most parsimonious explanation is that these are caused by the loss of visual input and the subsequent deprivation of the visual pathways and brain regions, rather than by transsynaptic degeneration. Moreover, and of clinical relevance, for some of the diseases - in particular glaucoma and AMD - present results are compatible with the view that the eye disease is part of a more general neurological or neurodegenerative disorder that also affects the brain. Finally, establishing structural changes of the visual pathways has been relevant in the context of new therapeutic strategies to restore retinal function: it implies that restoring retinal function may not suffice to also effectively restore vision. Future structural MRI studies can contribute to (i) further establish relationships between ocular and neurological neurodegenerative disorders, (ii) investigate whether brain degeneration in eye diseases is reversible, (iii) evaluate the use of neuroprotective medication in ocular disease, (iv) determine optimal timing for retinal implant insertion and (v) establish structural MRI examination as a diagnostic tool in ophthalmology.
Topics: Brain Diseases; Eye Diseases; Humans; Magnetic Resonance Imaging; Vision Disorders; Visual Acuity; Visual Cortex; Visual Fields; Visual Pathways
PubMed: 26361248
DOI: 10.1111/aos.12825 -
Nigerian Journal of Clinical Practice Mar 2017The use of smartphones for various purposes among health professionals is increasing, especially with the availability of different applications. On account of cost,...
BACKGROUND
The use of smartphones for various purposes among health professionals is increasing, especially with the availability of different applications. On account of cost, fundus cameras are not readily available in ophthalmic practice in developing countries. Since smartphones are readily available, easy to use and portable, they may present a cheap alternative in a resource-limited economy.
AIM AND OBJECTIVES
to explore the use of smartphone (Blackberry Z-10) for retinal imaging in a resource-limited economy.
METHODS
A smartphone (Blackberry Z-10) was used to acquire retinal images with the use of +20D lens in patients with dilated pupils by activating the video mode of the camera.
RESULTS
Clear retinal images were obtained in different clinical conditions in adults and children including branch retinal vein occlusion with fibrovascular proliferation, chorioretinal scarring from laser photocoagulation, presumed ocular toxoplasmosis, diabetic retinopathy, retinoblastoma, ocular albinism with fundus hypopigmentation.
CONCLUSION
The ability to have low cost fundus imaging from readily available smartphones in an eye clinic in Nigeria presents a major boost to patient care and also offers an innovative role in research, education, and information sharing.
Topics: Adolescent; Adult; Developing Countries; Female; Humans; Infant; Male; Middle Aged; Nigeria; Ophthalmoscopy; Photography; Retina; Retinal Diseases; Smartphone
PubMed: 28256490
DOI: 10.4103/1119-3077.201428 -
Acta Ophthalmologica Sep 2019Albinism degrades visual function due to developmental disorders of the eye and visual pathways, larger refractive errors, absent binocularity and poor fixation control.... (Comparative Study)
Comparative Study
PURPOSE
Albinism degrades visual function due to developmental disorders of the eye and visual pathways, larger refractive errors, absent binocularity and poor fixation control. Reading spectacles is commonly prescribed in our clinic and well tolerated. The purpose was to evaluate whether the accommodative response is typical or affected in comparison to a reference group.
METHODS
Twenty-two children with albinism (median: 13.5 years) and 12 controls (median: 13 years) underwent a full optometric examination and an objective accommodation measurement (WAM-5500 @ 6 Hz; Grand Seiko) in response to minus-lens-blur (-1, -2 and -3 D) and to a prolonged near viewing task (20 cm) for 5 min.
RESULTS
Children with albinism displayed less accommodation to minus lens-blur and during sustained near viewing (p < 0.001) compared to the reference group. Higher visual acuity correlates with a better accommodative response (r ≥ 0.5; p ≤ 0.04). The subjective and objective measures of accommodation did not correlate. The habitual reading distance was always closer than the point towards which the subjects with albinism seemed to accommodate according to the measurements at 20 cm.
CONCLUSION
Children with albinism benefits from reading spectacles due to a combination of close habitual reading distance and a poor accommodation. Objective recording of accommodation is not critical for a correct judgement of near visual function. Children already wearing reading spectacles were those with least accommodative response.
Topics: Accommodation, Ocular; Adolescent; Albinism; Child; Child, Preschool; Eyeglasses; Female; Humans; Infant; Infant, Newborn; Lens, Crystalline; Male; Reading; Refractive Errors; Vision, Binocular; Visual Acuity; Young Adult
PubMed: 30702212
DOI: 10.1111/aos.14040