an acuity of 6/60 (20/200) or worse, and often leave a person with complete blindness. Non-genetic causes
Physical trauma can cause color blindness, either neurologically – brain trauma which produces swelling of the brain in the occipital lobe – or retinally, either acute (e.g. from laser exposure) or chronic (e.g. from ultraviolet light exposure). Color blindness may also present itself as a symptom of degenerative diseases of the eye, such as cataract and age-related macular degeneration, and as part of the retinal damage caused by diabetes. Vitamin A deficiency may also cause color blindness.Color blindness may be a side effect of prescription drug use. For example, red–green color blindness can be caused by ethambutol, a drug used in the treatment of tuberculosis. Blue-yellow color blindness can be caused by sildenafil, an active component of Viagra. Hydroxychloroquine can also lead to hydroxychloroquine retinopathy, which includes various color defects. Exposure to chemicals such as styrene or organic solvents can also lead to color vision defects. Mechanism
Color blindness is any deviation of color vision from normal trichromatic color vision (often as defined by the standard observer) that produces a reduced gamut. Mechanisms for color blindness are related to the functionality of cone cells, and often to the expression of photopsins, the photopigments that catch photons and thereby convert light into chemical signals. When an individual does not satisfy the requirements for trichromatic vision, they will express dichromacy or monochromacy and be colorblind.
It should not be used in people with sick sinus syndrome, long QT syndrome, cardiogenic shock, uncontrolled heart failure, asthma or a related bronchospastic condition, or people with serum potassium below 4 meq/L. It should only be used in people with a second and third degree AV block if a functioning pacemaker is present.Since sotalol is removed from the body through the kidneys, it should not be used in people with a creatinine clearance rate below 40 mL/min. It is also excreted in breast milk, so mothers should not breastfeed while taking sotalol.Since sotalol prolongs the QT interval, the FDA recommends against using it in conjunction with other medications that prolong the QT interval. Studies have found serious side effects to be more common in individuals also taking digoxin, possibly because of pre-existing heart failure in those people. As with other beta blockers, it may interact with calcium channel blockers, catecholamine-depleting drugs, insulin or antidiabetic drugs, beta2-adrenergic agonists, and clonidine.Some evidence suggests that sotalol should be avoided in the setting of heart failure with a reduced ejection fraction (resulting in the heart squeezing little blood out into the circulation with each pump) due to an increased risk of death. Adverse effects
Over 10% of oral sotalol users experience fatigue, dizziness, lightheadedness, headache, weakness, nausea, shortness of breath, bradycardia (slow heart rate), a sensation of the heart beating too hard, fast, or irregularly, or chest pain.