The first symptom many individuals with choroideremia notice is a significant loss of night vision, which begins in youth. Peripheral vision loss occurs gradually, starting as a ring of vision loss, and continuing on to "tunnel vision" in adulthood. Individuals with choroideremia tend to maintain good visual acuity into their 40s, but eventually lose all sight at some point in the 50–70 age range. A study of 115 individuals with choroideremia found that 84% of patients under the age of 60 had a visual acuity of 20/40 or better, while 33% of patients over 60 years old had a visual acuity of 20/200 or worse. The most severe visual acuity impairment (only being able to count fingers or worse) did not occur until the seventh decade of life. The same study found the mean rate of visual acuity loss to be about 0.09 logMAR per 5 years, which is roughly 1 row on a Snellen chart. Diagnosis
A diagnosis of choroideremia can be made based on family history, symptoms and the characteristic appearance of the fundus. However, choroideremia shares several clinical features with retinitis pigmentosa, a similar but broader group of retinal degenerative diseases, making a specific diagnosis difficult without genetic testing. Because of this choroideremia is often initially misdiagnosed as retinitis pigmentosa. A variety of different genetic testing techniques can be used to make a differential diagnosis. Management
While nothing currently can be done to stop or reverse the retinal degeneration, there are steps that can be taken to slow the rate of vision loss.
Signs and symptoms
Most people who have taken too much of a calcium channel blocker, especially diltiazem, get slow heart rate and low blood pressure (vasodilatory shock). This can progress to the heart stopping altogether. CCBs of the dihydropyridine group, as well as flunarizine, predominantly cause reflex tachycardia as a reaction to the low blood pressure.Other potential symptoms include: nausea and vomiting, a decreased level of consciousness, and breathing difficulties. Symptoms usually begin within 6 hours of taking the medication by mouth. With extended release formulations symptoms may not occur for up to a day. Seizures are rare in adults but in children occur more often. Hypocalcaemia may also occur. Cause
Calcium channel blockers, also known as calcium channel antagonists, are widely used for a number of health conditions. Thus they are commonly present in many peoples homes. In young children one pill may cause serious health problems and potentially death. The calcium channel blocker that caused the greatest number of deaths in 2010 in the United States was verapamil. This agent is believed to cause more heart problems than many of the others. Diagnosis
A blood or urine test to diagnose overdose is not generally available. CCB overdose may cause high blood sugar levels, and this is often a sign of how severe the problem will become. Electrocardiogram
CCB toxicity can cause a number of electrocardiogram abnormalities with a low sinus rhythm being the most common. Others include: QT prolongation, bundle branch block, first-degree atrioventricular block, and even sinus tachycardia.