Refractive error
By The Treatment Registry editors
Myopia (short-sightedness), hyperopia (long-sightedness), and astigmatism are very common refractive errors corrected by glasses, contact lenses, or surgical refractive procedures. Surgical correction is elective and depends on stable refraction, healthy corneas of adequate thickness, and absence of conditions like keratoconus that contraindicate laser surgery.
Clinical overview
Signs and symptoms
Refractive error is a problem with focusing light accurately on the retina due to the shape of the eye and/or cornea. Its most common forms are near-sightedness (myopia), far-sightedness (hyperopia), and astigmatism. Near-sightedness makes distant objects appear blurry, far-sightedness makes close objects blurry, and astigmatism causes objects to appear stretched out or blurry. Other symptoms may include double vision, headaches, and eye strain. Because blurred vision can arise from many conditions not related to refractive error, the pattern of blur, together with these associated symptoms, characterises the presentation.
Causes and risk factors
The error arises from the optical geometry of the eye: near-sightedness is due to the eyeball being too long, far-sightedness to the eyeball being too short, and astigmatism to the cornea being the wrong shape. There is evidence of a genetic predisposition, and individuals whose parents have a given refractive error are more likely to have a similar one; myopia features as a symptom in many inherited disorders, including connective-tissue conditions such as Marfan, Stickler, and Knobloch syndromes. Environmental factors also correlate with myopia risk: it is more common in those with visually intensive occupations, and sustained focusing on near objects, such as reading, close screen use, or writing, has been associated with its development, as have higher socioeconomic status and education. Blepharoptosis can also induce refractive error.
How it is diagnosed
Diagnosis is confirmed by an eye care professional during an eye examination. The clinician determines an objective estimate of the error using lenses of different optical powers and a retinoscope, watching the pattern of reflected light while the patient views a distant target, a procedure called retinoscopy. This is refined by subjective refraction, in which lenses of progressively higher or weaker power are compared. An automated refractor is sometimes used in place of retinoscopy, and cycloplegic agents are frequently used to determine the error more accurately, particularly in children. A pinhole occluder distinguishes refractive error from other problems, as it improves vision only when the cause is refractive.
Who it affects
It is estimated that at least 2 billion people worldwide have refractive errors, making them the first common cause of visual impairment. The number with uncorrected refractive error was estimated at 660 million, or 10 per 100 people, in 2013, of whom 9.5 million were blind as a result. Rates vary between regions, with about 25% of Europeans and 80% of Asians affected. Near-sightedness is the most common form, with rates of 15 to 49% among adults and 1.2 to 42% among children, while far-sightedness more commonly affects young children and the elderly.
Clinical overview sourced from encyclopaedic medical reference; see sources below. General information only — not a substitute for individual clinical assessment.
Treatment ladder
Conservative options are first-line where appropriate; surgical options are typically reserved for cases where lower-tier options are unsuitable or have failed. Decisions are individual and depend on clinical assessment.
Conservative
- Spectacles
Reversible, no surgical risk. The default option and the appropriate baseline before considering refractive surgery.
- Contact lenses
Daily disposable, monthly, or extended-wear options. Careful hygiene reduces but does not eliminate microbial keratitis risk.
Procedural
- LASIK · View procedure page
Laser-assisted in-situ keratomileusis. Femtosecond-laser flap creation followed by excimer-laser stromal ablation. Rapid visual recovery and minimal post-operative discomfort.
- PRK
Photorefractive keratectomy: surface ablation without flap. Slower visual recovery and more discomfort than LASIK but suitable for thin corneas and contact-sport athletes.
- SMILE
Small-incision lenticule extraction: a stromal lenticule is created by a femtosecond laser and removed through a small incision, without a flap. Promoted as having better biomechanics than LASIK; evidence for advantages over LASIK is mixed.
- Implantable collamer lens (ICL)
Phakic intraocular lens for high myopia or thin corneas where laser refractive surgery is contraindicated. Lens-based, reversible.
Surgical
- Refractive lens exchange (RLE)
Replacement of the natural lens with an intraocular lens, similar to cataract surgery but performed for refractive correction. Particularly considered in presbyopic-age patients with high refractive errors unsuitable for laser surgery.
Related procedures
Sources
- [1]American Academy of Ophthalmology — Preferred Practice Patterns including Refractive Surgery — aao.org(accessed 2026-05-09)
- [2]Wikipedia — Refractive error — en.wikipedia.org(accessed 2026-07-24)
- [3]Cochrane Database — LASIK versus PRK for myopia — cochranelibrary.com(accessed 2026-05-09)
- [4]ESCRS — Clinical research and guidelines — escrs.org(accessed 2026-05-09)
Sources marked “on file” are held by The Treatment Registry but are not publicly accessible.