Farsightedness

In young patients, mild hypermetropia may not produce any symptoms. Hypermetropic patients with short axial length are at higher risk of developing primary angle closure glaucoma, so routine gonioscopy and glaucoma evaluation is recommended for all hypermetropic adults. ==Causes==

Simple hypermetropia, the most common form of hypermetropia, is caused by normal biological variations in the development of eyeball. • Curvatural: Curvatural hypermetropia occur when curvature of lens or cornea is flatter than normal. About 1 mm increase in radius of curvature results in 6 diopters of hypermetropia. Far-sightedness is often present from birth, but children have a very flexible eye lens, which helps to compensate. In rare instances, hyperopia can be due to diabetes, as well as problems with the blood vessels in the retina. ==Diagnosis==

A diagnosis of far-sightedness is made by utilizing either a retinoscope or an automated refractor-objective refraction; or trial lenses in a trial frame or a phoropter to obtain a subjective examination. Ancillary tests for abnormal structures and physiology can be made via a slit lamp test, which examines the cornea, conjunctiva, anterior chamber, and iris. In severe cases of hyperopia from birth, the brain has difficulty in merging the images that each individual eye sees. This is because the images the brain receives from each eye are always blurred. A child with severe hyperopia can never see objects in detail. If the brain never learns to see objects in detail, then there is a high chance of one eye becoming dominant. The result is that the brain will block the impulses of the non-dominant eye. In contrast, the child with myopia can see objects close to the eye in detail and does learn at an early age to see objects in detail. Classification Hyperopia is typically classified according to clinical appearance, its severity, or how it relates to the eye's accommodative status. Clinical classification There are three clinical categories of hyperopia. • Simple hyperopia: Occurs naturally due to biological diversity. • Pathological hyperopia: Caused by disease, trauma, or abnormal development. • Functional hyperopia: Caused by paralysis that interferes eye's ability to accommodate. Classification according to severity There are also three categories severity: • Low: Refractive error less than or equal to +2.00 diopters (D). • Moderate: Refractive error greater than +2.00 D up to +5.00 D. • High: Refractive error greater than +5.00 D. Components of hypermetropia Accommodation has significant role in hyperopia. Considering accommodative status, hyperopia can be classified as: • Total hypermetropia: It is the total amount of hyperopia which is obtained after complete relaxation of accommodation using cycloplegics like atropine. • Latent hyperopia: It is the amount of hyperopia normally corrected by ciliary tone (approximately 1 diopter). • Manifest hyperopia: It is the amount of hyperopia not corrected by ciliary tone. Manifest hyperopia is further classified into two, facultative and absolute. • Facultative hyperopia: It is the part of hyperopia corrected by patient's accommodation. • Absolute hyperopia: It is the residual part of hyperopia which causes blurring of vision for distance. So, Total hyperopia= latent hyperopia + manifest hyperopia (facultative + absolute) ==Treatment==

Corrective lenses The simplest form of treatment for far-sightedness is the use of corrective lenses, i.e. eyeglasses or contact lenses. Eyeglasses used to correct far-sightedness have convex lenses. Hyperopic PRK has many complications like regression effect, astigmatism due to epithelial healing, and corneal haze. Post operative epithelial healing time is also more for PRK. • Laser assisted in situ keratomileusis (LASIK): Laser eye surgery to reshape the cornea, so that glasses or contact lenses are no longer needed. Excimer laser LASIK can correct hypermetropia up to +6 diopters. • Phakic IOL: Phakic intraocular lens are lenses that implanted inside eye without removing the normal crystalline lens. Phakic IOLs can be used to correct hypermetropia up to +20 diopters. It uses radiofrequency energy to heat and shrink corneal collagen tissue. CK is contraindicated in pregnant/breastfeeding women, central corneal dystrophies and scarring, history of herpetic keratitis, type 1 diabetes etc. Poor predictability and the risk of complications limits usefulness of these procedures. • Keratophakia and epi-keratophakia are another two non laser surgical procedures used to correct hypermetropia. Keratophakia is a surgical technique developed by Barraquer for treating high hypermetropia and aphakia. Poor predictability and induced irregular astigmatism are complications of these procedures. ==Etymology==

The term hyperopia comes from Greek ὑπέρ hyper "over" and ὤψ ōps "sight" (GEN ὠπός ōpos). ==References==