Tests and diagnosisBy Mayo Clinic staff
To determine whether you have a cataract, your doctor will perform an eye exam that may include:
- Asking you to read an eye chart (visual acuity test). A visual acuity test uses an eye chart to measure how well you can read a series of letters. Your eyes are tested one at a time, while the other eye is covered. Using a chart or a viewing device with progressively smaller letters, your eye doctor determines if you have 20/20 vision or if your vision shows signs of impairment.
- Using a light and magnification to examine your eye (slit-lamp examination). A slit lamp allows your eye doctor to see the structures at the front of your eye under magnification. The microscope is called a slit lamp because it uses an intense line of light — a slit — to illuminate your cornea, iris, lens, and the space between your iris and cornea. The slit allows your doctor to view these structures in small sections, which makes it easier to detect any tiny abnormalities.
- Dilating your eyes (retinal examination). To prepare for a retinal examination, your eye doctor puts dilating drops in your eyes to open your pupils wide. This makes it easier to examine the back of your eyes (retina). Using a slit lamp or a special device called an ophthalmoscope, your eye doctor can examine your lens for signs of a cataract.
- Cataract: What you should know. National Eye Institute. http://www.nei.nih.gov/health/cataract/webcataract.pdf. Accessed April 12, 2010.
- Care of the adult patient with cataract. St. Louis, Mo.: American Optometric Association. http://www.aoa.org/documents/CPG-8.pdf. Accessed April 12, 2010.
- Wevill M. Epidemiology, pathophysiology, causes, morphology, and visual effects of cataract. In: Yanoff M, et al. Ophthalmology. 3rd ed. Philadelphia, Pa.: Mosby; 2008. http://www.mdconsult.com/das/book/body/194686199-3/0/1869/0.html. Accessed April 12, 2010.
- Cataract in the adult eye. American Academy of Ophthalmology. http://one.aao.org/asset.axd?id=821cecfb-85c5-400d-a65f-7a9a727bc163. Accessed April 12, 2010.
- Acquired cataract. In: Ehler JP, et al. The Wills Eye Manual: Office and Emergency Room Diagnosis and Treatment of Eye Disease. 5th ed. Baltimore, Md.: Lippincott Williams & Wilkins; 2008. http://ovidsp.ovid.com/ovidweb.cgi?T=JS&NEWS=N&PAGE=booktext&D=books&AN=01337416/5th_Edition/3&XPATH=/OVIDBOOK%5b1%5d/METADATA%5b1%5d/TBY%5b1%5d/EDITORS%5b1%5d. Accessed April 14, 2010.
- Guercio JR, et al. Congenital malformations of the eye and orbit. Otolaryngologic Clinics of North American. 2007;40:113.
- Abel R. Cataract. In: Rakel D. Integrative Medicine. 2nd ed. Philadelphia, Pa.: Saunders Elsevier; 2007. http://www.mdconsult.com/das/book/body/194686199-3/0/1494/0.html. Accessed April 12, 2010.
- Robertson DM (expert opinion). Mayo Clinic, Rochester, Minn. April 24, 2010.