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Posterior cortical atrophy (PCA), also called Benson's syndrome, is a rare form of dementia which is considered a visual variant or an atypical variant of Alzheimer's disease (AD). [ 1 ] [ 2 ] [ 3 ] The disease causes atrophy of the posterior part of the cerebral cortex , resulting in the progressive disruption of complex visual processing . [ 4 ]
There are many diseases known to cause ocular or visual changes. Diabetes , for example, is the leading cause of new cases of blindness in those aged 20–74, with ocular manifestations such as diabetic retinopathy and macular edema affecting up to 80% of those who have had the disease for 15 years or more.
In neurodegenerative diseases such as Alzheimer's disease, dementia with Lewy bodies, and Parkinson's disease, areas such as the basal ganglia, cerebral cortex, locus coeruleus, temporal, parietal and frontal lobes, and the limbic system, especially the hippocampus and amygdala, are impaired. [4]
The best vision might be in the centre (like tunnel vision) but more often it is at some other point, and it is difficult to tell what the person is really looking at. Note that if the person also has a common ocular visual impairment such as nystagmus then this can also affect which part(s) of the visual field are best.
The lens shape is changed for near focus (accommodation) and is controlled by the ciliary muscle. Between the two lenses (the cornea and the crystalline lens), there are four optical surfaces which each refract light as it travels along the optical path. One basic model describing the geometry of the optical system is the Arizona Eye Model. [2]
Vision can improve slowly after discontinuing ethambutol but rarely returns to baseline. Amiodarone is an antiarrhythmic medication commonly used for abnormal heart rhythms (atrial or ventricular tachyarrhythmias). Most patients on this medication get corneal epithelial deposits, but this medication has also been controversially associated with ...
This is a partial list of human eye diseases and disorders. The World Health Organization (WHO) publishes a classification of known diseases and injuries, the International Statistical Classification of Diseases and Related Health Problems , or ICD-10.
Diabetic Macular Edema (DME): is an eye disease specifically related to diabetes, occurring due to fluid build-up in the retina as a result of sustained high blood glucose levels. It can result in blurred vision and vision loss. [5] Eye floaters and spots: where visible cloud-like images appear to "float" in an individual's field of vision. [6]