Opened database successfully add two inverted commas for every one Comprehensive Medical Encyclopedia | Education for Healthcare Professionals

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Refractive Errors

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Urology

Version Jan 2023

About

Altered vision due to lens or corneal issues

Types

Cause	Details
Myopia (nearsightedness)	Distance vision is blurred because light rays are focused in front of fovea. Myopia is usually inherited and often discovered in childhood. Myopia often progresses throughout the teenage years when the body is growing rapidly.
Hyperopia (farsightedness)	Near vision is blurred because light rays are focused behind fovea. It can also be inherited. Children often have hyperopia, which may lessen in adulthood. In mild hyperopia, the distance vision is clear while near vision is blurry. In more advanced hyperopia, vision can be blurred at all distances
Astigmatism	Refraction unequal in different parts of eyeball. It usually occurs when the front surface of the eye, the cornea, has an asymmetric curvature. Normally the cornea is smooth and equally curved in all directions, and light entering the cornea is focused equally on all planes, or in all directions. See topic
Presbyopia	Age-related diminution in near vision. Onset usually noticed around ages 40+ years. The lens of the eye becomes more rigid and does not flex as easily. As a result, the eye loses its focusing ability and it becomes more difficult to read at close range. This normal ageing process of the lens can also be combined with myopia, hyperopia or astigmatism. There is no way to slow down or reverse presbyopia

Investigations

Sight testing

Management

Glasses and Contact lens to correct refractive errors
Laser in situ keratomileuses (LASIK) and photorefractive keratectomy (PRK) are used to alter the corneal surface and correct for some refractive issues

Revisions

Last updated 01/10/2017

PLEASE NOTE LEGAL ADVICE: The contents are under continuing development and improvements and may contain errors of omission or fact. The official launch will be at the end of 2018. Feedback vital and always welcome at drokane at gmail.com. This is not to be used for the assessment, diagnosis or management of patients. It should not be regarded as medical advice. It is only for educational purposes. Please adhere to your local protocols. If you are unwell please seek healthcare advice from your doctor. This does not replace senior or specialist advice. If you do not accept this then please do not use the website. If you need medical advice, please consult a doctor or other appropriate medical professional. If you are a medical professional and you need advice then speak to your senior or colleagues.

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