While it is uncommon, clozapine can cause changes in vision as a side effect, such as blurry revision or contrast sensitivity. Clozapine has anticholinergic activity, acting at muscarinic receptors. The most common visual side effect of anticholinergic medications is loss of accommodation. This can cause a decrease in the ability to focus on near objects and blurred vision at reading distance. With decreased accommodation, reading glasses may be necessary. Blurred vision at reading distance can be corrected with glasses. Anticholinergic medications can also cause pupil dilation, resulting in sensitivity to bright light. Other than clozapine, common medications with anticholinergic activity are diphenhydramine (found in Benadryl, allergy medications and sleep aids), the scopolamine patch, medications to reduce respiratory secretions, and some eye drops.