Clinical Characteristics of Visual Dysfunction in Carbon Monoxide Poisoning Patients

Abstract

Purpose. The aim of the present study was to analyze the clinical characteristics of visual dysfunction in patients with carbon monoxide (CO) poisoning. Methods. A total of 436 patients with CO poisoning were enrolled in our hospital from October 2012 to December 2018, including 193 patients with moderate poisoning (MP group), 165 with severe poisoning (SP group), and 78 with delayed encephalopathy (DE group). The clinical characteristics of visual dysfunction in patients with CO poisoning were analyzed through the collection of medical history, regular physical examination, brain magnetic resonance imaging (MRI), ophthalmological examination, the National Eye Institute Visual Function Questionnaire (NEI-VFQ), and its influencing factors. Results. Some patients in the three groups had visual dysfunction. The main ocular symptoms were local pain, eye movement disorder, and visual field defect. The key pathological factors were keratopathy, retinal nerve cell damage, optic nerve damage, retinal vascular disease, macular disease, and occipital visual center damage. The clinical symptoms of visual dysfunction after CO poisoning lasted for a long time (>12 months) and were not completely consistent with the positive results of the ophthalmological examination. A few sequelae of ophthalmology were still left after the help of medicine. Conclusion. The incidence of visual dysfunction in patients with CO poisoning was high, the clinical symptoms were rich and diverse, the duration of disease was long, and the prognosis was poor. Thus, the relevant ophthalmological examination and intervention treatment should be perfected as soon as possible.

Ambient Air Pollution and Age-Related Eye Disease: A Systematic Review and Meta-Analysis

“…Overall, findings from the systematic review suggest a potentially increased risk of AMD among individuals exposed to higher levels of CO 5 and PM 2.5 . 22 , 24 While only one study reported on CO and AMD, 5 the association is biologically plausible as increased CO exposure may induce an accumulation of oxidative stress in the retina, 26 which is particularly susceptible to this cellular damage due to its exposure to visible light, high proportion of polyunsaturated fatty acids, and high oxygen consumption, 27 thereby furthering the progression or development of AMD. Both Chua et al 22 and Grant et al 24 reported that higher exposures of PM 2.5 were associated with AMD or associated in a borderline fashion with visually impairing AMD, respectively.…”

Acute exposure to air pollutants increase the risk of acute glaucoma

“…A time series prospective study conducted in Chiang Mai, Thailand reported that NO 2 was positively associated with eye irritation (adjusted ORs (ROAORs: 1.024 to 1.229), and CO was positively related to lower heart and lung symptoms (adjusted ORs: 1.117 and 1.137) [ 58 ]. Large amount of CO could cause visual dysfunction [ 59 ]. It is interesting that low-dose CO inhalation protected RGCs from optic nerve injury [ 60 ], and carbon monoxide-releasing molecules (CORMs) derived from CO lowed IOP of rabbits in two ocular hypertension models [ 61 ].…”

Delayed Carbon Monoxide Optic Neuropathy

“…CO poisoning causes tissue ischemia and hypoxia, and the central nervous system (CNS), including the optic nerve, is particularly sensitive to this type of biological insult. The proposed mechanisms of CO poisoning–related optic neuropathy include both anterior and posterior visual pathway disturbances (3):Adenosine triphosphate–synthesis disorder with subsequent neurocyte edema and impairment to the visual center of the occipital lobe and visual radiation.Initial vasospasm followed by vasodilation, interstitial edema, and retardation of axoplasmic flow.Damage of vascular endothelial cells followed by increased platelet aggregation and adhesiveness, vasospasm, leukocyte aggregation, and other different cellular mechanisms resulting in local blood circulation disorders, such as microthrombosis.Oxidative stress that may lead to the selective degeneration of small optic nerve fibers.…”

“…Neurologic symptoms range from memory loss and behavioral impairment to seizures and coma. Despite the clinical improvement and the recovery of consciousness after CO poisoning, some patients still develop signs and symptoms of a delayed encephalopathy within 2–60 days of “false recovery period.” This delayed encephalopathy effect of CO poisoning has a high morbidity and mortality (3). The visual dysfunction induced by CO poisoning is common but variable, ranging from mild to serious visual function impairment including blindness (4).…”