They are encountered by up to 70% of all healthy people, though for most, it is quite infrequent. In some cases, the presence of fasciculations can be annoying and interfere with quality of life. If a neurological examination is otherwise normal and EMG testing does not indicate any additional pathology, a diagnosis of  benign fasciculation syndrome is usually made. Risk factors
Risk factors for benign fasciculations are age, stress, fatigue, and strenuous exercise. Fasciculations can be caused by anxiety, caffeine or alcohol and thyroid disease. Magnesium deficiency is a common cause of fasciculation.Other factors may include the use of anticholinergic drugs over long periods. In particular, these include ethanolamines such as diphenhydramine (brand names Benadryl, Dimedrol, Daedalon and Nytol), used as an antihistamine and sedative, and dimenhydrinate (brand names Dramamine, Driminate, Gravol, Gravamin, Vomex, and Vertirosan) for nausea and motion sickness. Persons with benign fasciculation syndrome (BFS) may experience paraesthesia (especially numbness) shortly after taking such medication; fasciculation episodes begin as the medication wears off. Stimulants can cause fasciculations directly. These include caffeine, pseudoephedrine (Sudafed), amphetamines, and the asthma bronchodilator salbutamol (brand names Proventil, Combivent, Ventolin). Medications used to treat attention deficit disorder (ADHD) often contain stimulants as well, and are common causes of benign fasciculations. Since asthma and ADHD are much more serious than the fasciculations themselves, this side effect may have to be tolerated by the patient after consulting a physician or pharmacist. The depolarizing neuromuscular blocker succinylcholine causes fasciculations.
Metamorphopsia is a type of distorted vision in which a grid of straight lines appears wavy and parts of the grid may appear blank. People can first notice they suffer with the condition when looking at mini-blinds in their home. For example, straight lines might be wavy or bendy. Things may appear closer or further than they are. Initially characterized in the 1800s, metamorphopsia was described as one of the primary and most notable indications of myopic and senile maculopathies. Metamorphopsia can present itself as unbalanced vision, resulting from small unintentional movements of the eye as it tries to stabilize the field of vision. Metamorphopsia can also lead to the misrepresentation of an object’s size or shape.It is mainly associated with macular degeneration, particularly age-related macular degeneration with choroidal neovascularization. Other conditions that can present with complaints of metamorphopsia include: pathological myopia, presumed ocular histoplasmosis syndrome, choroidal rupture and multifocal choroiditis. Pathology
The mechanisms that result in the development of metamorphopsia involve structural changes in the retina of the eye (retinal mechanism) as well as processing changes in the cerebral cortex of the brain (cortical mechanism). The retinal mechanism involves the displacement of retinal layers which results in the mislocation of light on the retina. The cortical mechanism, which was discovered after the retinal mechanism, is affected by perceptual “filling-in” and visual crowding effects. The cortical mechanism was found to work in combination with the retinal mechanism to contribute to metamorphopsia in long-standing maculopathy or after the treatment of macular disorders.