Sections

Keratoconus

Sections Keratoconus
Overview
Presentation
- History
- Physical
- Causes
- Complications
- Show All
DDx
Workup
Treatment
Medication
Media Gallery
References

Workup

Laboratory Studies

No laboratory workup is necessary in keratoconus, though genetic testing is commercially available to help identify the risk of a patient for develping KC.

After a comprehensive history, careful refraction, slit-lamp biomicroscopy, corneal topography, and corneal tomography allow the clinician to observe evidence and progression of KC. Corneal topography and tomography are the most sensitive methods of detecting the earliest signs of keratoconus and differentiate it from other cornea ectasias including pellucid marginal degeneration.

Imaging Studies

Corneal topography and corneal tomography are the standard diagnostic imaging tools used for the detection of keratoconus. These are especially useful when the typical biomicroscopy signs of Vogt striae and Fleischer ring are absent.

Corneal topography and tomography ^[38]

This commonly shows inferior corneal steepening in keratoconus, although a small percentage of patients with keratoconus show central astigmatic changes.

An even smaller number show superior peripheral steepening. Pellucid marginal degeneration typically shows an inferior lobster claw like map due to against-the-rule astigmatism.

Procedures

Pachymetry shows a thinner cornea paraxially.

Histologic Findings

All layers of the cornea are affected by keratoconus.

Superficial epithelial cells located at the nodule are elongated and arranged in a whorl-like fashion.

Iron deposition in the basal corneal epithelial cells form the characteristic Fleischer ring.

Localized breaks are present in the basement membrane.

A decrease in the number of stromal collagen lamellae is noted, as well as a loss of the fibular arrangement within the lamellae.^[39]

Folds and ruptures occur in the Descemet membrane. Some studies have reported endothelial cell loss in association with Descemet rupture.

Cornea thinning is caused by the splitting of the lamellae into multiple bundles of collagen fibrils.^[39]

Grading

Many grading are systems available to quantify the severity of keratoconus. Most systems consider the amount of corneal irregularity through higher-order aberrations and corneal thickness. Various nomograms have been proposed to quantify keratoconus, although no standard protocol is used for treatment.

Findings are as follows:

Normal: No clinical signs of keratoconus, no scissoring on retinoscopy, and symmetrical astigmatism
Keratoconus suspect: The fellow eye of an individual with keratoconus, with mild inferior steepening on topography and no clinical signs of keratoconus; the average K reading is less than 47 D
Forme fruste keratoconus: The fellow eye of an individual with keratoconus, with steeping seen on corneal topography and some corneal thinning seen on corneal tomography
Early keratoconus: No findings of keratoconus on slit-lamp examination; scissoring on retinoscopy; average K reading of less than 47 D
Keratoconus: Stromal corneal thinning on slit-lamp evaluation accompanied by one or more of the following clinical signs: Vogt striae, iron ring, Munson sign, scissoring on retinoscopy

Treatment & Management

Wisse RP, Kuiper JJ, Gans R, Imhof S, Radstake TR, Van der Lelij A. Cytokine Expression in Keratoconus and its Corneal Microenvironment: A Systematic Review. Ocul Surf. 2015 Oct. 13 (4):272-83. [QxMD MEDLINE Link].
Jun AS, Cope L, Speck C, Feng X, Lee S, Meng H, et al. Subnormal cytokine profile in the tear fluid of keratoconus patients. PLoS One. 2011 Jan 27. 6 (1):e16437. [QxMD MEDLINE Link].
Lema I, Sobrino T, Durán JA, Brea D, Díez-Feijoo E. Subclinical keratoconus and inflammatory molecules from tears. Br J Ophthalmol. 2009 Jun. 93 (6):820-4. [QxMD MEDLINE Link].
Gănescu AM. Current approaches in the management of patients with keratoconus. Med Pharm Rep. 2022 Oct. 95 (4):385-392. [QxMD MEDLINE Link].
Vohra V, Tuteja S, Gurnani B, Chawla H. Collagen Cross Linking For Keratoconus. 2022 Jan. [QxMD MEDLINE Link]. [Full Text].
Asimellis G, Kaufman EJ. Keratoconus. 2022 Jan. [QxMD MEDLINE Link]. [Full Text].
Critchfield JW, Calandra AJ, Nesburn AB, Kenney MC. Keratoconus: I. Biochemical studies. Exp Eye Res. 1988 Jun. 46(6):953-63. [QxMD MEDLINE Link].
Sawaguchi S, Yue BY, Sugar J, Gilboy JE. Lysosomal enzyme abnormalities in keratoconus. Arch Ophthalmol. 1989 Oct. 107(10):1507-10. [QxMD MEDLINE Link].
Gondhowiardjo TD, van Haeringen NJ. Corneal aldehyde dehydrogenase, glutathione reductase, and glutathione S-transferase in pathologic corneas. Cornea. 1993 Jul. 12(4):310-4. [QxMD MEDLINE Link].
Bykhovskaya Y, Margines B, Rabinowitz YS. Genetics in Keratoconus: where are we?. Eye Vis (Lond). 2016. 3:16. [QxMD MEDLINE Link].
Rabinowitz YS. The genetics of keratoconus. Ophthalmol Clin North Am. 2003 Dec. 16 (4):607-20, vii. [QxMD MEDLINE Link].
Galvis V, Sherwin T, Tello A, Merayo J, Barrera R, Acera A. Keratoconus: an inflammatory disorder?. Eye (Lond). 2015 Jul. 29 (7):843-59. [QxMD MEDLINE Link].
Özalp O, Atalay E, Yıldırım N. Prevalence and risk factors for keratoconus in a university-based population in Turkey. J Cataract Refract Surg. 2021 Dec 1. 47 (12):1524-1529. [QxMD MEDLINE Link].
Papaliʼi-Curtin AT, Cox R, Ma T, Woods L, Covello A, Hall RC. Keratoconus Prevalence Among High School Students in New Zealand. Cornea. 2019 Nov. 38 (11):1382-1389. [QxMD MEDLINE Link].
Bak-Nielsen S, Ramlau-Hansen CH, Ivarsen A, Plana-Ripoll O, Hjortdal J. Incidence and prevalence of keratoconus in Denmark - an update. Acta Ophthalmol. 2019 Dec. 97 (8):752-755. [QxMD MEDLINE Link].
Torres Netto EA, Al-Otaibi WM, Hafezi NL, et al. Prevalence of keratoconus in paediatric patients in Riyadh, Saudi Arabia. British Journal of Ophthalmology. 2018. 102:1436-1441.
Gorskova EN, Sevost'ianov EN. [Epidemiology of keratoconus in the Urals]. Vestn Oftalmol. 1998 Jul-Aug. 114 (4):38-40. [QxMD MEDLINE Link].
Ihalainen A. Clinical and epidemiological features of keratoconus genetic and external factors in the pathogenesis of the disease. Acta Ophthalmol Suppl (1985). 1986. 178:1-64. [QxMD MEDLINE Link].
Godefrooij DA, de Wit GA, Uiterwaal CS, Imhof SM, Wisse RP. Age-specific Incidence and Prevalence of Keratoconus: A Nationwide Registration Study. Am J Ophthalmol. 2017 Mar. 175:169-172. [QxMD MEDLINE Link].
Krachmer JH, Feder RS, Belin MW. Keratoconus and related noninflammatory corneal thinning disorders. Surv Ophthalmol. 1984 Jan-Feb. 28 (4):293-322. [QxMD MEDLINE Link].
Zadnik K, Barr JT, Edrington TB, et al. Baseline findings in the Collaborative Longitudinal Evaluation of Keratoconus (CLEK) Study. Invest Ophthalmol Vis Sci. 1998 Dec. 39(13):2537-46. [QxMD MEDLINE Link].
Cristina Kenney M, Brown DJ. The cascade hypothesis of keratoconus. Cont Lens Anterior Eye. 2003 Sep. 26(3):139-46. [QxMD MEDLINE Link].
Sherwin T, Brookes NH. Morphological changes in keratoconus: pathology or pathogenesis. Clin Experiment Ophthalmol. 2004 Apr. 32(2):211-7. [QxMD MEDLINE Link].
Woodward MA, Blachley TS, Stein JD. The Association Between Sociodemographic Factors, Common Systemic Diseases, and Keratoconus: An Analysis of a Nationwide Heath Care Claims Database. Ophthalmology. 2015 Dec 16. [QxMD MEDLINE Link].
Flockerzi E, Xanthopoulou K, Goebels SC, Zemova E, Razafimino S, Hamon L, et al. Keratoconus staging by decades: a baseline ABCD classification of 1000 patients in the Homburg Keratoconus Center. Br J Ophthalmol. 2021 Aug. 105 (8):1069-1075. [QxMD MEDLINE Link].
Ertan A, Muftuoglu O. Keratoconus clinical findings according to different age and gender groups. Cornea. 2008 Dec. 27 (10):1109-13. [QxMD MEDLINE Link].
Millodot M, Ortenberg I, Lahav-Yacouel K, Behrman S. Effect of ageing on keratoconic corneas. J Optom. 2015 Jun 30. [QxMD MEDLINE Link].
Yeung KK et al. Where have all the keratoconics gone?. Int Cont Lens Clin. 1998. 25(4):109-13.
Popiela M, Young-Zvandasara T, Veepanat E, Saunders D. Demographics of older keratoconics in Wales and their mortality rates-Where are the older keratoconics?. Cont Lens Anterior Eye. 2016 Oct. 39 (5):365-8. [QxMD MEDLINE Link].
Moodaley LC, Woodward EG, Liu CS, Buckley RJ. Life expectancy in keratoconus. Br J Ophthalmol. 1992 Oct. 76(10):590-1. [QxMD MEDLINE Link]. [Full Text].
Sarezky D, Orlin SE, Pan W, VanderBeek BL. Trends in Corneal Transplantation in Keratoconus. Cornea. 2017 Feb. 36 (2):131-137. [QxMD MEDLINE Link].
Moschos MM, Nitoda E, Georgoudis P, Balidis M, Karageorgiadis E, Kozeis N. Contact Lenses for Keratoconus- Current Practice. Open Ophthalmol J. 2017. 11:241-251. [QxMD MEDLINE Link].
Dienes L, Kiss HJ, Perényi K, Nagy ZZ, Acosta MC, Gallar J, et al. Corneal Sensitivity and Dry Eye Symptoms in Patients with Keratoconus. PLoS One. 2015. 10 (10):e0141621. [QxMD MEDLINE Link].
Aldave AJ, Ann LB, Frausto RF, Nguyen CK, Yu F, Raber IM. Classification of posterior polymorphous corneal dystrophy as a corneal ectatic disorder following confirmation of associated significant corneal steepening. JAMA Ophthalmol. 2013 Dec. 131 (12):1583-90. [QxMD MEDLINE Link].
Shajari M, Eberhardt E, Müller M, Al Khateeb G, Friderich S, Remy M, et al. Effects of Atopic Syndrome on Keratoconus. Cornea. 2016 Nov. 35 (11):1416-1420. [QxMD MEDLINE Link].
Gupta PK, Stinnett SS, Carlson AN. Prevalence of sleep apnea in patients with keratoconus. Cornea. 2012 Jun. 31(6):595-9. [QxMD MEDLINE Link].
Rabinowitz YS. The genetics of keratoconus. Ophthalmol Clin North Am. 2003 Dec. 16(4):607-20, vii. [QxMD MEDLINE Link].
Rabinowitz YS, Li X, Canedo AL, Ambrósio R Jr, Bykhovskaya Y. Optical coherence tomography combined with videokeratography to differentiate mild keratoconus subtypes. J Refract Surg. 2014 Feb. 30 (2):80-7. [QxMD MEDLINE Link].
Mathew JH, Goosey JD, Söderberg PG, Bergmanson JP. Lamellar changes in the keratoconic cornea. Acta Ophthalmol. 2015 Dec. 93 (8):767-73. [QxMD MEDLINE Link].
Compañ V, Aguilella-Arzo M, Edrington TB, Weissman BA. Modeling Corneal Oxygen with Scleral Gas Permeable Lens Wear. Optom Vis Sci. 2016 Nov. 93 (11):1339-1348. [QxMD MEDLINE Link].
Rathi VM, Mandathara PS, Dumpati S. Contact lens in keratoconus. Indian J Ophthalmol. 2013 Aug. 61 (8):410-5. [QxMD MEDLINE Link].
Wollensak G, Spoerl E, Seiler T. Riboflavin/ultraviolet-a-induced collagen crosslinking for the treatment of keratoconus. Am J Ophthalmol. 2003 May. 135 (5):620-7. [QxMD MEDLINE Link].
Tomita M, Mita M, Huseynova T. Accelerated versus conventional corneal collagen crosslinking. J Cataract Refract Surg. 2014 Jun. 40 (6):1013-20. [QxMD MEDLINE Link].
Acar BT, Utine CA, Ozturk V, Acar S, Ciftci F. Can the effect of transepithelial corneal collagen cross-linking be improved by increasing the duration of topical riboflavin application? An in vivo confocal microscopy study. Eye Contact Lens. 2014 Jul. 40 (4):207-12. [QxMD MEDLINE Link].
Wittig-Silva C, Chan E, Islam FM, Wu T, Whiting M, Snibson GR. A randomized, controlled trial of corneal collagen cross-linking in progressive keratoconus: three-year results. Ophthalmology. 2014 Apr. 121 (4):812-21. [QxMD MEDLINE Link].
Sherif AM, Ammar MA, Mostafa YS, Gamal Eldin SA, Osman AA. One-Year Results of Simultaneous Topography-Guided Photorefractive Keratectomy and Corneal Collagen Cross-Linking in Keratoconus Utilizing a Modern Ablation Software. J Ophthalmol. 2015. 2015:321953. [QxMD MEDLINE Link].
Kymionis GD, Portaliou DM, Kounis GA, Limnopoulou AN, Kontadakis GA, Grentzelos MA. Simultaneous topography-guided photorefractive keratectomy followed by corneal collagen cross-linking for keratoconus. Am J Ophthalmol. 2011 Nov. 152(5):748-55. [QxMD MEDLINE Link].
Ferenczy PA, Dalcegio M, Koehler M, Pereira TS, Moreira H, Luciane Bugmann M. Femtosecond-assisted intrastromal corneal ring implantation for keratoconus treatment: a comparison with crosslinking combination. Arq Bras Oftalmol. 2015 Mar-Apr. 78 (2):76-81. [QxMD MEDLINE Link].
Kymionis GD, Grentzelos MA, Karavitaki AE, Zotta P, Yoo SH, Pallikaris IG. Combined corneal collagen cross-linking and posterior chamber toric implantable collamer lens implantation for keratoconus. Ophthalmic Surg Lasers Imaging. 2011 Feb 17. 42 Online:e22-5. [QxMD MEDLINE Link].
Alnawaiseh M, Rosentreter A, Eveslage M, Eter N, Zumhagen L. Changes in Corneal Transparency After Cross-linking for Progressive Keratoconus: Long-term Follow-up. J Refract Surg. 2015 Sep. 31 (9):614-8. [QxMD MEDLINE Link].
Raiskup F, Hoyer A, Spoerl E. Permanent corneal haze after riboflavin-UVA-induced cross-linking in keratoconus. J Refract Surg. 2009 Sep. 25 (9):S824-8. [QxMD MEDLINE Link].
Shalchi Z, Wang X, Nanavaty MA. Safety and efficacy of epithelium removal and transepithelial corneal collagen crosslinking for keratoconus. Eye (Lond). 2015 Jan. 29 (1):15-29. [QxMD MEDLINE Link].
Kymionis GD, Bouzoukis DI, Diakonis VF, Portaliou DM, Pallikaris AI, Yoo SH. Diffuse lamellar keratitis after corneal crosslinking in a patient with post-laser in situ keratomileusis corneal ectasia. J Cataract Refract Surg. 2007 Dec. 33 (12):2135-7. [QxMD MEDLINE Link].
Labiris G, Kaloghianni E, Koukoula S, Zissimopoulos A, Kozobolis VP. Corneal melting after collagen cross-linking for keratoconus: a case report. J Med Case Rep. 2011 Apr 16. 5:152. [QxMD MEDLINE Link].
Sharma A, Nottage JM, Mirchia K, Sharma R, Mohan K, Nirankari VS. Persistent corneal edema after collagen cross-linking for keratoconus. Am J Ophthalmol. 2012 Dec. 154 (6):922-926.e1. [QxMD MEDLINE Link].
Kymionis GD, Portaliou DM, Diakonis VF, Kounis GA, Panagopoulou SI, Grentzelos MA. Corneal collagen cross-linking with riboflavin and ultraviolet-A irradiation in patients with thin corneas. Am J Ophthalmol. 2012 Jan. 153 (1):24-8. [QxMD MEDLINE Link].
Zamora KV, Males JJ. Polymicrobial keratitis after a collagen cross-linking procedure with postoperative use of a contact lens: a case report. Cornea. 2009 May. 28 (4):474-6. [QxMD MEDLINE Link].
Ferrari G, Iuliano L, Viganò M, Rama P. Impending corneal perforation after collagen cross-linking for herpetic keratitis. J Cataract Refract Surg. 2013 Apr. 39 (4):638-41. [QxMD MEDLINE Link].
Raiskup F, Spoerl E. Corneal crosslinking with riboflavin and ultraviolet A. Part II. Clinical indications and results. Ocul Surf. 2013 Apr. 11 (2):93-108. [QxMD MEDLINE Link].
Sharif R, Fowler B, Karamichos D. Collagen cross-linking impact on keratoconus extracellular matrix. PLoS One. 2018. 13 (7):e0200704. [QxMD MEDLINE Link].
van Dijk K, Liarakos VS, Parker J, Ham L, Lie JT, Groeneveld-van Beek EA, et al. Bowman layer transplantation to reduce and stabilize progressive, advanced keratoconus. Ophthalmology. 2015 May. 122 (5):909-17. [QxMD MEDLINE Link].
Reddy JC, Hammersmith KM, Nagra PK, Rapuano CJ. The role of penetrating keratoplasty in the era of selective lamellar keratoplasty. Int Ophthalmol Clin. 2013 Spring. 53 (2):91-101. [QxMD MEDLINE Link].
Wisse RP, van den Hoven CM, Van der Lelij A. Does lamellar surgery for keratoconus experience the popularity it deserves?. Acta Ophthalmol. 2014 Aug. 92 (5):473-7. [QxMD MEDLINE Link].
Coster DJ, Lowe MT, Keane MC, Williams KA, Australian Corneal Graft Registry Contributors. A comparison of lamellar and penetrating keratoplasty outcomes: a registry study. Ophthalmology. 2014 May. 121 (5):979-87. [QxMD MEDLINE Link].
Arnalich-Montiel F, Alió Del Barrio JL, Alió JL. Corneal surgery in keratoconus: which type, which technique, which outcomes?. Eye Vis (Lond). 2016. 3:2. [QxMD MEDLINE Link].
Lowe MT, Keane MC, Coster DJ, Williams KA. The outcome of corneal transplantation in infants, children, and adolescents. Ophthalmology. 2011 Mar. 118 (3):492-7. [QxMD MEDLINE Link].
Pramanik S, Musch DC, Sutphin JE, Farjo AA. Extended long-term outcomes of penetrating keratoplasty for keratoconus. Ophthalmology. 2006 Sep. 113 (9):1633-8. [QxMD MEDLINE Link].
Choi JA, Lee MA, Kim MS. Long-term outcomes of penetrating keratoplasty in keratoconus: analysis of the factors associated with final visual acuities. Int J Ophthalmol. 2014. 7 (3):517-21. [QxMD MEDLINE Link].
Javadi MA, Motlagh BF, Jafarinasab MR, Rabbanikhah Z, Anissian A, Souri H, et al. Outcomes of penetrating keratoplasty in keratoconus. Cornea. 2005 Nov. 24 (8):941-6. [QxMD MEDLINE Link].
Niziol LM, Musch DC, Gillespie BW, Marcotte LM, Sugar A. Long-term outcomes in patients who received a corneal graft for keratoconus between 1980 and 1986. Am J Ophthalmol. 2013 Feb. 155 (2):213-219.e3. [QxMD MEDLINE Link].
Moschos MM, Gouliopoulos NS, Kalogeropoulos C, Androudi S, Kitsos G, Ladas D, et al. Psychological Aspects and Depression in Patients with Symptomatic Keratoconus. J Ophthalmol. 2018. 2018:7314308. [QxMD MEDLINE Link].
Kymes SM, Walline JJ, Zadnik K, Sterling J, Gordon MO, Collaborative Longitudinal Evaluation of Keratoconus Study Group. Changes in the quality-of-life of people with keratoconus. Am J Ophthalmol. 2008 Apr. 145 (4):611-617. [QxMD MEDLINE Link].
Mannis MJ, Ling JJ, Kyrillos R, Barnett M. Keratoconus and Personality-A Review. Cornea. 2018 Mar. 37 (3):400-404. [QxMD MEDLINE Link].
Weissman B, Chun MW, Barnhart LA. Corneal abrasion associated with contact lens correction of keratoconus--a retrospective study. Optom Vis Sci. 1994 Nov. 71(11):677-81. [QxMD MEDLINE Link].
Pearson AR, Soneji B, Sarvananthan N, Sandford-Smith JH. Does ethnic origin influence the incidence or severity of keratoconus?. Eye (Lond). 2000 Aug. 14 ( Pt 4):625-8. [QxMD MEDLINE Link].
Rabinowitz YS. Keratoconus. Surv Ophthalmol. 1998 Jan-Feb. 42(4):297-319. [QxMD MEDLINE Link].
Kennedy RH, Bourne WM, Dyer JA. A 48-year clinical and epidemiologic study of keratoconus. Am J Ophthalmol. 1986 Mar 15. 101(3):267-73. [QxMD MEDLINE Link].
Sawaguchi S, Twining SS, Yue BY, et al. Alpha 2-macroglobulin levels in normal human and keratoconus corneas. Invest Ophthalmol Vis Sci. 1994 Nov. 35(12):4008-14. [QxMD MEDLINE Link].
Fukuchi T, Yue BY, Sugar J, Lam S. Lysosomal enzyme activities in conjunctival tissues of patients with keratoconus. Arch Ophthalmol. 1994 Oct. 112(10):1368-74. [QxMD MEDLINE Link].
Kenney MC, Nesburn AB, Burgeson RE, Butkowski RJ, Ljubimov AV. Abnormalities of the extracellular matrix in keratoconus corneas. Cornea. 1997 May. 16(3):345-51. [QxMD MEDLINE Link].
Behndig A, Karlsson K, Johansson BO, Brännström T, Marklund SL. Superoxide dismutase isoenzymes in the normal and diseased human cornea. Invest Ophthalmol Vis Sci. 2001 Sep. 42(10):2293-6. [QxMD MEDLINE Link].
Buddi R, Lin B, Atilano SR, Zorapapel NC, Kenney MC, Brown DJ. Evidence of oxidative stress in human corneal diseases. J Histochem Cytochem. 2002 Mar. 50(3):341-51. [QxMD MEDLINE Link].
Atilano SR, Coskun P, Chwa M, Jordan N, Reddy V, Le K. Accumulation of mitochondrial DNA damage in keratoconus corneas. Invest Ophthalmol Vis Sci. 2005 Apr. 46(4):1256-63. [QxMD MEDLINE Link].
Kenney MC, Chwa M, Atilano SR, Tran A, Carballo M, Saghizadeh M. Increased levels of catalase and cathepsin V/L2 but decreased TIMP-1 in keratoconus corneas: evidence that oxidative stress plays a role in this disorder. Invest Ophthalmol Vis Sci. 2005 Mar. 46(3):823-32. [QxMD MEDLINE Link].
Meek KM, Tuft SJ, Huang Y, Gill PS, Hayes S, Newton RH, et al. Changes in collagen orientation and distribution in keratoconus corneas. Invest Ophthalmol Vis Sci. 2005 Jun. 46(6):1948-56. [QxMD MEDLINE Link].
Määttä M, Heljasvaara R, Sormunen R, Pihlajaniemi T, Autio-Harmainen H, Tervo T. Differential expression of collagen types XVIII/endostatin and XV in normal, keratoconus, and scarred human corneas. Cornea. 2006 Apr. 25(3):341-9. [QxMD MEDLINE Link].
Määttä M, Väisänen T, Väisänen MR, Pihlajaniemi T, Tervo T. Altered expression of type XIII collagen in keratoconus and scarred human cornea: Increased expression in scarred cornea is associated with myofibroblast transformation. Cornea. 2006 May. 25(4):448-53. [QxMD MEDLINE Link].
Ku JY, Niederer RL, Patel DV, Sherwin T, McGhee CN. Laser scanning in vivo confocal analysis of keratocyte density in keratoconus. Ophthalmology. 2008 May. 115(5):845-50. [QxMD MEDLINE Link].
Lema I, Durán JA. Inflammatory molecules in the tears of patients with keratoconus. Ophthalmology. 2005 Apr. 112(4):654-9. [QxMD MEDLINE Link].
Lema I, Durán JA, Ruiz C, Díez-Feijoo E, Acera A, Merayo J. Inflammatory response to contact lenses in patients with keratoconus compared with myopic subjects. Cornea. 2008 Aug. 27(7):758-63. [QxMD MEDLINE Link].
Macsai MS, Varley GA, Krachmer JH. Development of keratoconus after contact lens wear. Patient characteristics. Arch Ophthalmol. 1990 Apr. 108(4):534-8. [QxMD MEDLINE Link].
Li X, Yang H, Rabinowitz YS. Keratoconus: classification scheme based on videokeratography and clinical signs. J Cataract Refract Surg. 2009 Sep. 35 (9):1597-603. [QxMD MEDLINE Link].
Steinberg J, Aubke-Schultz S, Frings A, Hülle J, Druchkiv V, Richard G, et al. Correlation of the KISA% index and Scheimpflug tomography in 'normal', 'subclinical', 'keratoconus-suspect' and 'clinically manifest' keratoconus eyes. Acta Ophthalmol. 2015 May. 93 (3):e199-207. [QxMD MEDLINE Link].
Zadnik K, Barr JT, Gordon MO, Edrington TB. Biomicroscopic signs and disease severity in keratoconus. Collaborative Longitudinal Evaluation of Keratoconus (CLEK) Study Group. Cornea. 1996 Mar. 15(2):139-46. [QxMD MEDLINE Link].
Wagner H, Barr JT, Zadnik K. Collaborative Longitudinal Evaluation of Keratoconus (CLEK) Study: methods and findings to date. Cont Lens Anterior Eye. 2007 Sep. 30(4):223-32. [QxMD MEDLINE Link].
Zadnik K, Barr JT, Gordon MO, Edrington TB. Biomicroscopic signs and disease severity in keratoconus. Collaborative Longitudinal Evaluation of Keratoconus (CLEK) Study Group. Cornea. 1996 Mar. 15(2):139-46. [QxMD MEDLINE Link].
Ridley F. EYE-RUBBING AND CONTACT LENSES. Br J Ophthalmol. 1961 Sep. 45(9):631. [QxMD MEDLINE Link].
Karseras AG, Ruben M. Aetiology of keratoconus. Br J Ophthalmol. 1976 Jul. 60(7):522-5. [QxMD MEDLINE Link].
Jaynes J, Weissman BA, Edrington T. Predicting scleral GP lens entrapped tear layer oxygen tensions. Cont Lens Anterior Eye. 2015 Oct. 38 (5):392. [QxMD MEDLINE Link].
Bykhovskaya Y, Li X, Epifantseva I, Haritunians T, Siscovick D, Aldave A. Variation in the lysyl oxidase (LOX) gene is associated with keratoconus in family-based and case-control studies. Invest Ophthalmol Vis Sci. 2012. 53(7):4152-7. [QxMD MEDLINE Link].
Nielsen K, Hjortdal J, Pihlmann M, Corydon TJ. Update on the keratoconus genetics. Acta Ophthalmol. 2012 Apr 4. [QxMD MEDLINE Link].
Chang CY, Hersh PS. Corneal collagen cross-linking: a review of 1-year outcomes. Eye Contact Lens. 2014 Nov. 40 (6):345-52. [QxMD MEDLINE Link].
Tuft SJ, Hassan H, George S, Frazer DG, Willoughby CE, Liskova P. Keratoconus in 18 pairs of twins. Acta Ophthalmol. 2012 Sep. 90(6):e482-6. [QxMD MEDLINE Link].
Farjadnia M, Naderan M. Corneal cross-linking treatment of keratoconus. Oman J Ophthalmol. 2015 May-Aug. 8 (2):86-91. [QxMD MEDLINE Link].
Georgiou T, Funnell CL, Cassels-Brown A, O'Conor R. Influence of ethnic origin on the incidence of keratoconus and associated atopic disease in Asians and white patients. Eye (Lond). 2004 Apr. 18(4):379-83. [QxMD MEDLINE Link].
Alió JL, Shabayek MH. Corneal higher order aberrations: a method to grade keratoconus. J Refract Surg. 2006 Jun. 22(6):539-45. [QxMD MEDLINE Link].
American Academy of Ophthalmology 2013 Annual Meeting. Presented November 16, 2013.
Colin J, Malet FJ. Intacs for the correction of keratoconus: two-year follow-up. J Cataract Refract Surg. 2007 Jan. 33(1):69-74. [QxMD MEDLINE Link].
Fontana L, Parente G, Tassinari G. Clinical outcomes after deep anterior lamellar keratoplasty using the big-bubble technique in patients with keratoconus. Am J Ophthalmol. 2007 Jan. 143(1):117-124. [QxMD MEDLINE Link].
Goodman A. Crosslinking safe in children, adolescents with keratoconus. Medscape Medical News. November 28, 2013. Available at http://www.medscape.com/viewarticle/815184. Accessed: December 7, 2013.
Jafri B, Li X, Yang H, Rabinowitz YS. Higher order wavefront aberrations and topography in early and suspected keratoconus. J Refract Surg. 2007 Oct. 23(8):774-81. [QxMD MEDLINE Link].
Kelly TL, Williams KA, Coster DJ. Corneal transplantation for keratoconus: a registry study. Arch Ophthalmol. 2011 Jun. 129(6):691-7. [QxMD MEDLINE Link].
Kosaki R, Maeda N, Bessho K, Hori Y, Nishida K, Suzaki A. Magnitude and orientation of Zernike terms in patients with keratoconus. Invest Ophthalmol Vis Sci. 2007 Jul. 48(7):3062-8. [QxMD MEDLINE Link].
Rabinowitz YS. Intacs for keratoconus. Curr Opin Ophthalmol. 2007 Jul. 18(4):279-83. [QxMD MEDLINE Link].
Raiskup-Wolf F, Hoyer A, Spoerl E, Pillunat LE. Collagen crosslinking with riboflavin and ultraviolet-A light in keratoconus: long-term results. J Cataract Refract Surg. 2008 May. 34(5):796-801. [QxMD MEDLINE Link].
Schlegel Z, Hoang-Xuan T, Gatinel D. Comparison of and correlation between anterior and posterior corneal elevation maps in normal eyes and keratoconus-suspect eyes. J Cataract Refract Surg. 2008 May. 34(5):789-95. [QxMD MEDLINE Link].
Shimmura S, Tsubota K. Deep anterior lamellar keratoplasty. Curr Opin Ophthalmol. 2006 Aug. 17(4):349-55. [QxMD MEDLINE Link].
Sorbara L, Dalton K. The use of video-keratoscopy in predicting contact lens parameters for keratoconic fitting. Cont Lens Anterior Eye. 2010 Jun. 33(3):112-8. [QxMD MEDLINE Link].
Rathi VM, Mandathara PS, Dumpati S. Contact lens in keratoconus. Indian J Ophthalmol. 2013 Aug. 61 (8):410-5. [QxMD MEDLINE Link].
Raiskup F, Spoerl E. Corneal crosslinking with riboflavin and ultraviolet A. Part II. Clinical indications and results. Ocul Surf. 2013 Apr. 11 (2):93-108. [QxMD MEDLINE Link].
Nattis A, Donnenfeld ED, Rosenberg E, Perry HD. Visual and keratometric outcomes of keratoconus patients after sequential corneal crosslinking and topography-guided surface ablation: Early United States experience. J Cataract Refract Surg. 2018 Aug. 44 (8):1003-1011. [QxMD MEDLINE Link].

Media Gallery

An optic section of a keratoconic cornea shows corneal thinning. Vogt striae and some scarring can also be seen centrally; superiorly, a small (brown) section of the Fleischer ring is noted.
The fluorescein pattern of a rather flat-fitted rigid contact lens on an advanced keratoconic cornea.

of 2

Author

Karen K Yeung, OD, FAAO Senior Optometrist, UCLA Arthur Ashe Student Health and Wellness Center; Clinical Assistant Professor, College of Optometry, Western University of Health Sciences

Karen K Yeung, OD, FAAO is a member of the following medical societies: American Academy of Optometry

Disclosure: Nothing to disclose.

Coauthor(s)

Barry A Weissman, OD, PhD, FAAO Retired Professor of Optometry, Southern California College of Optometry at Marshall B Ketchum University; Professor Emeritus of Ophthalmology, Stein Eye Institute, University of California, Los Angeles, David Geffen School of Medicine

Barry A Weissman, OD, PhD, FAAO is a member of the following medical societies: American Academy of Optometry, American Optometric Association, California Optometric Society, International Society for Contact Lens Research

Disclosure: Nothing to disclose.

Specialty Editor Board

Francisco Talavera, PharmD, PhD Adjunct Assistant Professor, University of Nebraska Medical Center College of Pharmacy; Editor-in-Chief, Medscape Drug Reference

Disclosure: Received salary from Medscape for employment. for: Medscape.

Christopher J Rapuano, MD Professor, Department of Ophthalmology, Sidney Kimmel Medical College of Thomas Jefferson University; Director of the Cornea Service, Wills Eye Hospital

Christopher J Rapuano, MD is a member of the following medical societies: American Academy of Ophthalmology, American Ophthalmological Society, American Society of Cataract and Refractive Surgery, Contact Lens Association of Ophthalmologists, Cornea Society, Eye Bank Association of America, International Society of Refractive Surgery

Disclosure: Serve(d) as a director, officer, partner, employee, advisor, consultant or trustee for: AAO; OMIC; American Society of Ophthalmic Trauma (ASOT); Avellino, Baxis; Bio-Tissue; Celularity; Dompe; Emmecell; Glaukos; Kala; Oyster Point; Sun Ophthalmics; Tarsus; TearLab<br/>Serve(d) as a speaker or a member of a speakers bureau for: Glaukos; Dompe; Bio-Tissue<br/>Received research grant from: Glaukos<br/>Received income in an amount equal to or greater than $250 from: AAO; OMIC; Baxis; Bio-Tissue; Cellularity; Dompe; Glaukos; Kala; Sun Ophthalmics; TearLab<br/>stock options for: RPS, Fount Bio.

Chief Editor

Hampton Roy, Sr, MD † Associate Clinical Professor, Department of Ophthalmology, University of Arkansas for Medical Sciences

Hampton Roy, Sr, MD is a member of the following medical societies: American Academy of Ophthalmology, American College of Surgeons, Pan-American Association of Ophthalmology

Disclosure: Nothing to disclose.

Additional Contributors

Fernando H Murillo-Lopez, MD Senior Surgeon, Unidad Privada de Oftalmologia CEMES

Fernando H Murillo-Lopez, MD is a member of the following medical societies: American Academy of Ophthalmology

Disclosure: Nothing to disclose.

Sections Keratoconus
Overview
Presentation
- History
- Physical
- Causes
- Complications
- Show All
DDx
Workup
Treatment
Medication
Media Gallery
References

Keratoconus Workup

Laboratory Studies

Imaging Studies

Procedures

Histologic Findings

Grading

References

Tables

Contributor Information and Disclosures

What would you like to print?