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Tests and diagnosis
By Mayo Clinic staffYour ophthalmologist can diagnose keratoconus during a routine eye exam, but more sophisticated tests may be done to determine the exact shape of your cornea. Tests to diagnose keratoconus include:
- Eye refraction. In this standard vision test, your eye doctor uses special equipment that measures your eyes to check for clear vision, astigmatism and other vision problems. The first measurement is taken by a computerized refractor or by retinoscopy, a light that's reflected by your retina. Then, your eye doctor may ask you to look through a Phoroptor, a mask-like device that contains wheels of different lenses, in order to find the combination that gives you the sharpest vision.
- Slit-lamp examination. This test shines a vertical beam of light on the surface of your eye while the ophthalmologist looks through a low-powered microscope to view the shape of your cornea. The test may be repeated after eyedrops are used to dilate your pupils so that the ophthalmologist can assess the back of your cornea.
- Keratometry. A single circle of light is focused on your cornea, and the reflection of light is used to measure your cornea's curvature and radius.
- Topographical measuring devices. If more precise measurements of your cornea's surface are needed, a computer scans your cornea and generates a topographical map of your eye's surface.
References
- Nordan LT. Keratoconus: diagnosis and treatment. International Ophthalmology Clinics. 1997;37(1):51-63.
- Koster AR, et al. Topographical analysis of keratoconus. International Ophthalmology Clinics. 1993;33(2):261-269.
- Lembach RG. Keratoconus. International Ophthalmology Clinics. 1991;31(2):71-82.
- Rabinowitz YS. Intacs for keratoconus. Current Opinion in Ophthalmology. 2007;18:279-283.
- Tan DTH, et al. Current treatment options for corneal ectasia. Current Opinion in Ophthalmology. 2007;18:284-289.
- Tan BU, et al. New surgical approaches to the management of keratoconus and post-LASIK ectasia. Transactions of the American Ophthalmologic Society. 2006;104:212-221.
- Brierly SC, et al. Penetrating keratoplasty for keratoconus. Cornea. 2000;19(3):329-332.
- Rabinowitz YS. INTACS for keratoconus. International Ophthalmology Clinics. 2006;46(3):91-103.
- Crosby MB, et al. Management of keratoconus. Contemporary Ophthalmology. 2007;6(9):1-8.
- Krachmer JH. Eye rubbing can cause keratoconus (comment). Cornea. 2004;23(6)539-540.
