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Non-Organic Vision Loss
Published in Vivek Lal, A Clinical Approach to Neuro-Ophthalmic Disorders, 2023
Ashwini Kini, Mangayarkarasi Thandampallayam Ajjeya, Padmaja Sudhakar
Retrobulbar optic neuritis: In the majority of cases, the fundus appears normal. Careful eye exam looking for RAPD will help in the diagnosis, but subtle RAPD might be missed in some cases. Visual field examination will show central scotoma in early cases, but if the disease has progressed there might be only a small island of preserved vision. Imaging with MRI orbit with and without contrast can usually show an enhancing optic nerve on T1 post contrast. Further testing with OCT to demonstrate the progression of loss of nerve fiber layer thickness over time may be used as a marker of loss of function of optic nerve.
Central Scotoma
Published in K. Gupta, P. Carmichael, A. Zumla, 100 Short Cases for the MRCP, 2020
K. Gupta, P. Carmichael, A. Zumla
The common causes of a central scotoma are: Retrobulbar neuritis, most commonly in cases of multiple sclerosis.Choroidoretinitis.Pressure on the optic nerve by a tumour.Optic atrophy due to toxins or vitamin B12 deficiency.
How to master MCQs
Published in Chung Nen Chua, Li Wern Voon, Siddhartha Goel, Ophthalmology Fact Fixer, 2017
Optic nerve trauma in head injuries often occurs in the intracanalicular portion. The visual field defect is usually a central scotoma. Optic atrophy is common and the visual evoked potential will show a delayed latency. Optic nerve fenestration is usually performed in patients with optic nerve sheath haematoma -however, in most traumatic optic neuropathies the optic nerve appears normal on CT or MRl scan, and optic nerve fenestration is of uncertain benefit in such cases.
Glaucoma Mimickers: A major review of causes, diagnostic evaluation, and recommendations
Published in Seminars in Ophthalmology, 2021
Sirisha Senthil, Mamata Nakka, Virender Sachdeva, Shaveta Goyal, Nibedita Sahoo, Nikhil Choudhari
Hereditary optic neuropathy: Hereditary optic neuropathies are classically characterized by temporal disc pallor and central/centrocecal scotomas (Figure 12).40,41 However, most of these patients have increased cupping, which might mimic glaucomatous disc damage. Morphologically, these patients have a wedge-shaped area of optic disc pallor in the temporal rim. Most patients also have broad central scotoma. Other clues that might help in establishing the diagnosis include a family history of poor vision; temporal pallor that is similar in both eyes; autosomal dominant optic atrophy; associated diabetes mellitus, diabetes insipidus; sensorineural hearing loss (DIDMOAD/Wolfram syndrome); and sequential involvement of both eyes in patients with Leber’s hereditary optic neuropathy (LHON), with poor/suboptimal recovery. Genetic testing can help establish the diagnosis. Autosomal dominant optic atrophy: Among the various forms of hereditary optic neuropathy, autosomal dominant optic atrophy is the most common. This condition, also known as Kjer’s optic atrophy, is characterized by an insidious onset and might be detected accidentally during routine evaluation.42 The majority of patients have good or slightly subnormal vision, but optic disc usually shows temporal disc pallor, sectoral excavation of the optic disc, and increase in the size of the optic disc cupping.
Effectiveness of Low Vision Rehabilitation Using Microperimetric Acoustic Biofeedback Training in Patients with Central Scotoma
Published in Current Eye Research, 2021
Esra Sahli, Deniz Altinbay, Pınar Bingol Kiziltunc, Aysun Idil
Several diseases, including the macular area, lead to a central scotoma which affects visual function and quality of life. In most patients, functional adaptations can take place to compensate for the reduced central vision. The patients adapt to an extra-scotomatous area for fixation which is called the preferred retinal locus (PRL).4 Studies indicate that individuals adapt to using an eccentric locus for fixation typically within the first 6 months, but efficient use of PRL requires extensive training.5 Areas with highest retinal sensitivity that are physically closer to the old foveola are prime candidates to be the PRL.6,7 Potentially, such retinal loci are expected to provide better visual function unmatched by any other locus on the retina but, these areas may not always be the ones with the best potential for visual function.8 It is demonstrated that the PRL did not predict better visual acuity and contrast sensitivity levels and PRL and highest retinal sensitivity loci are not identical in patients with age-related macular degeneration (AMD).9,10 Poor fixation stability is expected to be correlated with poor visual acuity and poor reading speed.5–8 The location and characteristics of the PRL can be identified with microperimetry.
MFSD8 gene mutations; evidence for phenotypic heterogeneity
Published in Ophthalmic Genetics, 2019
Davood Zare-Abdollahi, Ata Bushehri, Afagh Alavi, Alireza Dehghani, Mohammadreza Mousavi-Mirkala, Jalil Effati, Seyed Ali Mohammad Miratashi, Mohammad Dehani, Payman Jamali, Hamid Reza Khorram Khorshid
Cone–rod dystrophies (CRDs) are a group of genetically and phenotypically heterogeneous inherited degenerative retinal diseases primarily affecting macular and cone system function (1,2), resulting in progressive visual decline (3). CRDs are generally characterized by decreased visual acuity, photophobia, sensitivity to glare, and color vision defect, followed by partial impairment of peripheral vision and, ultimately, in most patients nyctalopia years later (1). However, age of onset, progression of the disease, severity of cone dystrophy, and possibility of night blindness varied greatly among different affected individuals (2). Fundoscopic appearance demonstrates foveal involvement, ranging from normal to a bull’s eye maculopathy, or total macular atrophy, and the pallor of optic disc to some extent plus potential evidence of rod dysfunction (4). The visual field is affected by a central scotoma (blind spots) that appears first, followed by patchy losses of peripheral vision, and finally severe impairment of vision that occurs earlier than in retinitis pigmentosa (5). In addition, upraising the threshold of psychophysical dark-adapted cone system and diminishing amplitude of electroretinogram, predominantly in phototopic rather than scotopic responses, are likely to be seen (1).