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An Approach to Visual Loss in a Child
Published in Vivek Lal, A Clinical Approach to Neuro-Ophthalmic Disorders, 2023
Muhammad Hassaan Ali, Stacy L. Pineles
Impaired vision in early childhood can be due to multiple causes that include congenital malformations, acquired ophthalmic disorders, or lesions of the anterior or posterior visual pathway. A careful examination of the patient can help the clinician identify some of the evident anterior segment disorders like congenital cataract, corneal opacities and refractive errors. However, some retinal pathologies like congenital stationary night blindness (CSNB), Leber's congenital amaurosis (LCA) and achromatopsia do not show any characteristic lesions on the retina in early stages and have to be diagnosed on the basis of electroretinography (ERG) (1–3). An important finding in all such cases is arteriolar narrowing and waxy disc pallor which should alert the clinician to order ERG in such cases (4). It is generally advised to wait till 1 year of life to derive conclusive findings from ERG owing to slow maturation of rod and cone maturation in the first year of life. Similarly, cerebral visual impairment may also be suspected clinically but demands detailed high-resolution neuroimaging for confirmation.
The eye
Published in Angus Clarke, Alex Murray, Julian Sampson, Harper's Practical Genetic Counselling, 2019
A clear primary diagnosis for nystagmus is essential because the causes may be neurological or vestibular as well as ocular. Even when the nystagmus is primary, there are a number of causes. Probably the most important ones to recognise are the various types of albinism, congenital stationary night blindness (see earlier) and the X-linked hereditary oculomotor nystagmus, which shows very variable manifestation in females (see Figure 2.22).
Impairment of visual functions
Published in Ramar Sabapathi Vinayagam, Integrated Evaluation of Disability, 2019
Retinitis pigmentosa, vitamin A deficiency, glaucoma, X-linked congenital stationary night blindness, gyrate atrophy, Laurence-Moon syndrome, Oguchi disease, optic atrophy, peripheral chorioretinitis, siderosis retinae, cancer-associated retinopathy or hypoxia, and uncorrected myopia causes night blindness (nyctalopia). If night blindness is irreversible even after maximum medical management, Integrated Evaluation of Disability assigns an impairment of 25%.
Photoaversion in inherited retinal diseases: clinical phenotypes, biological basis, and qualitative and quantitative assessment
Published in Ophthalmic Genetics, 2022
Serena Zaman, Thomas Kane, Mohamed Katta, Michalis Georgiou, Michel Michaelides
When we consider the other end of the spectrum of photoreceptor disorders, the clinical features are notably different. In those with progressive rod-cone dystrophies (including retinitis pigmentosa and Leber Congenital Amaurosis (LCA)/Early-onset severe retinal dystrophy (EOSRD)), PA may be observed only once cone loss is very significant (advanced disease) (28). The exception being LCA/EOSRD genotypes, which are characterised by a greater degree of cone than rod loss at early stages (thereby more in keeping with cone-rod dystrophies), e.g. GUCY2D-associated LCA (29). Those with predominantly stationary rod dysfunction syndromes, including congenital stationary night blindness, do not experience photoallodynia, or only mildly when there is a significant degree of loss in cone function (15).
NYX-related Congenital Stationary Night Blindness in Two Siblings due to Probable Maternal Germline Mosaicism
Published in Ophthalmic Genetics, 2021
H. l. Scanga, A. Liasis, M. S. Pihlblad, K. K. Nischal
Congenital Stationary Night Blindness (CSNB) describes a group of inherited retinal disorders featuring both clinical and genetic heterogeneity. The ocular manifestations of CSNB may include nystagmus, myopia, strabismus, defective dark adaptation, and decreased visual acuity ranging from 20/20 to 20/200 (1–3). CSNB is grouped functionally into complete and incomplete forms, which are distinguishable by electroretinography (3–5). At least 17 genes have been associated with CSNB, which may be inherited in an autosomal dominant, autosomal recessive, or X-linked recessive manner (1). X-linked forms of CSNB are predominant, where pathogenic variants of NYX and CACNA1F are associated with the complete (cCSNB or CSNB1) and incomplete forms (iCSNB or CSNB2), respectively (1,5–8).
Patient-reported outcome measures in inherited retinal degeneration gene therapy trials
Published in Ophthalmic Genetics, 2020
Gabrielle D. Lacy, Maria Fernanda Abalem, David C. Musch, Kanishka T. Jayasundera
Apart from RP, only two PROs have been developed to target other IRDs. Miedziak et al. studied 200 patients with Stargardt’s disease to better characterize the condition (35). The group created a PRO tool based on existing instruments and patient input. While a strength of this PRO is its development in a large Stargardt’s population, applying this PRO to all other IRDs would be inappropriate. Additionally, the validation methods of this PRO instrument are unclear. In a study of 101 Congenital Stationary Night Blindness (CSNB) patients, Bijveld et al. attempted to specifically address night vision and created a PRO instrument that was based on existing low luminance questionnaires with some additional questions (1). While CSNB is an inherited retinal condition, the non-progressive nature of CSNB as well as the isolated symptom of night blindness are key distinguishers that limit the use of this PRO in a larger IRD population.