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Toxins in Neuro-Ophthalmology
Published in Vivek Lal, A Clinical Approach to Neuro-Ophthalmic Disorders, 2023
Toxicity includes keratopathy, ciliary body involvement, lens opacities and retinopathy. Retinopathy is the major concern although others are more common but benign. Risk factors of retinopathy include age, daily as well as cumulative dosage, treatment duration and coexisting retinal, renal or liver disease. Visual symptoms include decreased vision, missing central vision, glare, blurred vision, light flashes and metamorphopsia. Characteristic fundus finding is bull's-eye maculopathy. All patients have field defects including paracentral, pericentral, central and peripheral field loss. Color vision is impaired in the advanced stage. Regular screening may be necessary to detect reversible premaculopathy. Cessation of the drug is the only effective management of the toxicity.
Spectral Imaging Technologies and Apps and Dual-Layer Detector Solution
Published in Katsuyuki Taguchi, Ira Blevis, Krzysztof Iniewski, Spectral, Photon Counting Computed Tomography, 2020
Nadav Shapira, Yoad Yagil, Naor Wainer, Ami Altman
Following the principle of natural selection, two kinds of photoreceptor cell evolved with different energy response. While these new types of photoreceptor cells still maintain the basic mechanism of response that is dependent on the total amount of absorbed energy, each type exhibits a different spectral sensitivity, i.e., different detection efficiencies for the same light spectrum. That is, not to say that there is a complete energy separation between the two spectral responses, but that, despite the partial overlap between the two response spectra, a different detection signal is produced by each type of photoreceptor cell. This new scheme allowed for the differentiation between objects or surfaces that presented little or no signal difference in the one-dimensional scheme and provided an evolutionary advantage in various situations. The interpretation of the signals by the brain is now referred to as color vision, which combines information of both the integrated energy and the wavelength contrasts to detect objects for signals from cells, or channels, in the same areas of visual space. When the integrated energy contrast between different objects is absent or insufficient, “wavelength contrast” [1] may still be available to differentiate between them – it may be that two objects reflect the same amount of energy; however, it is unlikely that they reflect the same wavelength composition.
Cardiovascular Toxicology
Published in Frank A. Barile, Barile’s Clinical Toxicology, 2019
The manifestations of DG toxicity involve the CV, the central nervous system (CNS), and the GI tract. The hallmark of cardiac toxicity is an increased automaticity coupled with concomitant conduction delay. Although no single dysrhythmia is frequently present, certain aberrations such as premature ventricular beats, bradyrhythmias, paroxysmal atrial tachycardia with block, junctional tachycardia, and bidirectional ventricular tachycardia are common. DG toxicity is also manifest as dysfunction of the CNS, including delirium, fatigue, malaise, confusion, dizziness, abnormal dreams, blurred or yellow vision, and halos. Disturbances of color vision are frequently reported. A patient’s complaint of a “whitish, yellowish halo vision” is a suspicious sign of digoxin intoxication. GI disturbances may include anorexia, nausea, vomiting, and abdominal pain.
Ocular side effects of systemic isotretinoin – a systematic review and summary of case reports
Published in Journal of Dermatological Treatment, 2023
Olivia Lamberg, Arianna Strome, Foster Jones, Julia Mleczek, Adrienne Jarocki, Jonathon P. Troost, Yolanda Helfrich
Vision changes included visual acuity change, refractive vision changes, nyctalopia, and abnormal color vision. Nine studies (4684 total patients) reported the proportion of patients experiencing visual acuity changes (1,68,74,78–80,92–94). The overall reported incidence is 3% (95% CI: 0%, 4%) with heterogeneity of p < 0.01 (Figure 3.10). Six studies (4211 total patients) reported the proportion of patients experiencing nyctalopia (1,70,78,93,95,96). The overall reported incidence is 1% (95% CI: 0%, 3%) with heterogeneity of p < 0.01 (Figure 3.11). Three studies (85 total patients) reported the proportion of patients experiencing refractive vision change (94,97,98). The overall reported incidence is 0% (95% CI: 0%, 3%) with heterogeneity of p = 0.99 (Figure 3.12). Three studies (111 total patients) reported the continuous refractive vision changes from before and during isotretinoin treatment (81,99,100). There was an overall −0.08 change (95% CI: −0.23, 0.05) after initiation of isotretinoin treatment (Figure 3.13). Two studies (43 total patients) reported the proportion of patients experiencing abnormal color vision deficiency (68,101). The overall reported incidence is 2% (95% CI: 0%, 8%) (Figure 3.14). Overall, in unique 18 studies reporting on 5265 total patients, the overall reported incidence of vision changes ranged from 0–3%, with 3 studies reporting a 0.08 decrease in refractive vision associated with isotretinoin.
Ocular Manifestations After Acute Methanol Poisoning
Published in Neuro-Ophthalmology, 2023
Maamouri Rym, Nabi Wijden, Maamouri Héla, Sassi Héla, Brahmi Nozha, Monia Cheour
This is a case series including patients diagnosed with acute methanol poisoning following the ingestion of cologne and adulterated alcohol from an illicit production who were hospitalised in the department of intensive care medicine and clinical toxicology (CAMU) in Tunis, Tunisia, during an outbreak in 2020. All patients underwent a complete ophthalmological examination in the ophthalmology department of Habib Thameur hospital in Tunis, Tunisia, including measurement of best-corrected Snellen visual acuity (VA), pupillary examination, Lanthony Desaturated D-15 colour vision testing, automated 24–2 visual field testing, slit-lamp examination and dilated fundus examination. Normal colour vision was defined as normal trichromacy and defective colour vision was defined as mild, moderate or severe abnormal trichromacy or dichromacy. Reliability indices (name, demographic data, fixation loss, false positive and false negative) were verified before interpretation of the automated visual fields. Mean retinal nerve fibre layer (RNFL) thickness was assessed from images acquired using the swept source optical coherence tomography (OCT) (DRI-OCT-1, Topcon, Tokyo, Japan). The study protocol followed the tenets of the Declaration of Helsinki.
Neuro-Ophthalmic Literature Review
Published in Neuro-Ophthalmology, 2022
David A. Bellows, John J. Chen, Jenny A. Nij Bijvank, Michael S. Vaphiades, Xiaojun Zhang
The authors conducted a retrospective study of 14 paediatric patients who underwent optic nerve sheath fenestration for papilloedema at the Children’s Hospital of Philadelphia. Ten (71%) were female and their ages ranged from 8.5 to 17.5. Ten of these patients had a diagnosis of idiopathic intracranial hypertension. Five patients underwent bilateral optic nerve sheath fenestration. Visual acuity improved from 20/138 to 20/68 in the operated eye and from 20/78 to 20/32 in the non-operated eye. Visual field mean deviation improved from −23.4 dB to −11.5 dB in the operated eye and from −19.8 dB to −6.8 dB in the non-operated eye. Colour vision significantly improved in the operated eyes. In the operated eyes, extra-ocular motility was abnormal in 13 (72.2%) eyes at presentation and improved to three (15.8%) at final visit, while the non-operated eye had abnormal extra-ocular motility in four (44.4%) eyes at presentation and all improved at final visit. Retinal nerve fibre layer thickness improved in the operated eye from 349.1 to 66.2 µm. In 13 out of 14 patients, optic nerve pallor was noted at the final visit. Improvement in some aspects of visual function was seen as early as post-operative day 1, such as visual acuity in the non-operated eye, while other variables reached a significant improvement 1 week or 1 month after surgery. None of the patients suffered any adverse effects from the optic nerve sheath fenestration procedure.