• A slit lamp can help detect eye disease and other problems.eye image by Pali A from Fotolia.com
  
  A slit lamp is an instrument that is used in a specific type of eye examination, called a slit lamp exam. The device is a microscope that projects a high intensity beam of light through an adjustable narrow slit and onto the patient's eye. Eye doctors use this instrument primarily to examine the front of the eye in an effort to detect diseases, but it has several other functions as well.
  
  

Front Eye Exam

• Eye doctors use the slit lamp to examine the front portions of the eye, including the cornea, the lens and the iris (colored portion). The slit lamp's focused light and the magnified view of the eye that it provides help determine the presence of cataracts, conjunctivitis (pinkeye), iritis (inflammation of the iris) or injury or infection to the cornea.
  
  

Back of the Eye

• The slit lamp can also be equipped to view the back of the eye. Special magnifying lenses are inserted between the slit lamp and the eye to project the light further into the eye. This allows the doctor to examine the retina and the optic nerve. Doctors normally dilate the patient's eyes for this type of examination.
  
  

Fragment Detection

• A slit lamp can also be used to detect tiny foreign particles that may be caught in the eye, causing irritation. To aid in this function, doctors inject a dye into the cornea. The dye creates contrast for the light of the slit lamp, so foreign objects can be more easily detected.
  
  

Glaucoma and Macular Degeneration

• The slit lamp further functions as a detection and monitoring device for glaucoma and macular degeneration, particularly for those who suffer from diabetes or rheumatoid arthritis. These maladies commonly lead to eye problems. According to WebMD, routine slit lamp exams increase the chance of early detection of glaucoma or macular degeneration, leading to more effective treatment.