Keratoconus

Not to be confused with Ketyconus.

Keratoconus
Other namesKC, KCN, conical cornea[1]
The "cone shaped cornea" that is characteristic of keratoconus
Pronunciation
  • KEHR-uh- toh-KOH-nus[2]
SpecialtyOphthalmology, optometry
SymptomsBlurry vision, nearsightedness, light sensitivity[3]
Usual onsetEarly adulthood[3]
CausesUnknown[3]
Diagnostic methodSlit lamp exam[3]
TreatmentGlasses, contacts, surgery[3]
Frequency~1 in 2,000 people[3]

Keratoconus (KC) is a disorder of the eye that results in progressive thinning of the cornea.[3] This may result in blurry vision, double vision, nearsightedness, irregular astigmatism,[4] and light sensitivity leading to poor quality-of-life.[3][5] Usually both eyes are affected.[3] In more severe cases a scarring or a circle may be seen within the cornea.[6]

While the cause is unknown, it is believed to occur due to a combination of genetic, environmental, and hormonal factors.[3] Patients with a parent, sibling, or child who has keratoconus have 15 to 67 times higher risk in developing corneal ectasia compared to patients with no affected relatives.[7][8] Proposed environmental factors include rubbing the eyes and allergies.[6] The underlying mechanism involves changes of the cornea to a cone shape.[3] Diagnosis is most often by topography. Topography measures the curvature of the cornea and creates a colored "map" of the cornea. Keratoconus causes very distinctive changes in the appearance of these maps, which allows doctors to make the diagnosis.

Initially the condition can typically be corrected with glasses or soft contact lenses.[3] As the disease progresses, special contact lenses (such as scleral contact lenses) may be required.[3] In most people the disease stabilizes after a few years without severe vision problems.[3] In 2016, the FDA approved corneal collagen cross-linking to halt the progression of keratoconus.[9] In some cases when the cornea becomes dangerously thin or when sufficient vision can no longer be achieved by contact lenses due to steepening of the cornea, scarring or lens intolerance, corneal cross-linking is not an option and a corneal transplant may be required.

Keratoconus affects about 1 in 2,000 people.[3][6] However, some estimates suggest that the incidence may be as high as 1 in 400 individuals.[10] It occurs most commonly in late childhood to early adulthood.[3] While it occurs in all populations, it may be more frequent in certain ethnic groups such as those of Asian descent.[6] The word is from the Greek kéras meaning cornea and the Latin cōnus meaning cone.[11]

  1. ^ "Keratoconus". NORD (National Organization for Rare Disorders). Archived from the original on 19 February 2017.
  2. ^ "Keratoconus" (PDF). The University of Texas Health Science Center at San Antonio. Archived (PDF) from the original on 8 September 2017.
  3. ^ a b c d e f g h i j k l m n o p "Facts About the Cornea and Corneal Disease". NEI. May 2016. Archived from the original on 22 November 2016. Retrieved 5 November 2016.
  4. ^ "Cornea Research Foundation of America - Keratoconus". www.cornea.org.
  5. ^ Kandel H, Pesudovs K, Watson SL (March 2020). "Measurement of Quality of Life in Keratoconus". Cornea. 39 (3): 386–393. doi:10.1097/ICO.0000000000002170. ISSN 0277-3740. PMID 31599780. S2CID 204029105.
  6. ^ a b c d Romero-Jiménez M, Santodomingo-Rubido J, Wolffsohn JS (1 August 2010). "Keratoconus: a review". Contact Lens & Anterior Eye: The Journal of the British Contact Lens Association. 33 (4): 157–166, quiz 205. doi:10.1016/j.clae.2010.04.006. ISSN 1476-5411. PMID 20537579.
  7. ^ Fecarotta C, Huang W (27 July 2015). "Pediatric genetic disease of the cornea". Journal of Pediatric Genetics. 03 (4): 195–207. doi:10.3233/PGE-14102. ISSN 2146-4596. PMC 5021007. PMID 27625877.
  8. ^ Wang Y, Rabinowitz Y, Rotter J, Yang H (2000). <403::aid-ajmg11>3.0.co;2-a "Genetic epidemiological study of keratoconus: Evidence for major gene determination". American Journal of Medical Genetics. 93 (5): 403–409. doi:10.1002/1096-8628(20000828)93:5<403::aid-ajmg11>3.0.co;2-a. ISSN 0148-7299. PMID 10951465.
  9. ^ Cite error: The named reference :0 was invoked but never defined (see the help page).
  10. ^ "Keratoconus - NORD".
  11. ^ "Keratoconus Origin". dictionary.com. Archived from the original on 8 January 2016. Retrieved 2 November 2015.