Additional concerns exist with views of compromising the freedom of choice to donate, conflicts with extant religious beliefs and the possibility of posthumous violations of bodily integrity. Even though concerns exist, the United States still has a 95 percent organ donation approval rate. This level of nationwide acceptance may foster an environment where moving to a policy of presumed consent may help solve some of the organ shortage problem, where individuals are assumed to be willing organ donors unless they document a desire to "opt-out", which must be respected.Because of public policies, cultural, infrastructural and other factors, presumed consent or opt-out models do not always translate directly into increased effective rates of donation. The United Kingdom has several different laws and policies for the organ donation process, such as consent of a witness or guardian must be provided to participate in organ donation. This policy is currently being consulted on by Department of Health and Social Care.In terms of effective organ donations, in some systems like Australia (14.9 donors per million, 337 donors in 2011), family members are required to give consent or refusal, or may veto a potential recovery even if the donor has consented. Some countries with an opt-out system like Spain (40.2 donors per million inhabitants), Croatia (40.2 donors/million) or Belgium (31.6 donors/million) have high donor rates, however some countries such as Greece (6 donors/million) maintain low donor rates even with this system.
Diagnosis
A diagnosis of myopia is typically made by an eye care professional, usually an optometrist or ophthalmologist. During a refraction, an autorefractor or retinoscope is used to give an initial objective assessment of the refractive status of each eye, then a phoropter is used to subjectively refine the patients eyeglass prescription. Other types of refractive error are hyperopia, astigmatism, and presbyopia. Types
Various forms of myopia have been described by their clinical appearance:
Simple myopia: Myopia in an otherwise normal eye, typically less than 4.00 to 6.00 diopters. This is the most common form of myopia. Degenerative myopia, also known as malignant, pathological, or progressive myopia, is characterized by marked fundus changes, such as posterior staphyloma, and associated with a high refractive error and subnormal visual acuity after correction. This form of myopia gets progressively worse over time. Degenerative myopia has been reported as one of the main causes of visual impairment. Pseudomyopia is the blurring of distance vision brought about by spasm of the accommodation system. Nocturnal myopia: Without adequate stimulus for accurate accommodation, the accommodation system partially engages, pushing distance objects out of focus. Nearwork-induced transient myopia (NITM): short-term myopic far point shift immediately following a sustained near visual task. Some authors argue for a link between NITM and the development of permanent myopia. Instrument myopia: over-accommodation when looking into an instrument such as a microscope.