Diagnosis
What are the Causes of Keratoconus?
The cause of keratoconus is still a mystery. It is likely triggered by genetic, environmental, and/or cellular factors. Vigorous eye rubbing contributes to the progression of the disease. Eye rubbing should definitely be avoided. One theory suggests that deficient collagen cross-linking caused by free radicals contributes to keratoconus, but scientific evidence does not conclusively support this theory at this time.
How is Keratoconus Diagnoised?
The first symptom of keratoconus is usually blurred vision, which prompts a person to go to the doctor seeking corrective lenses for reading or driving. At this stage, the symptoms are no different than for any other refractive problem of the eye. However, vision deteriorates as keratoconus progresses, sometimes rapidly. Vision becomes worse at all distances; night vision can be quite poor; vision may be worse in one eye; sensitivity to light can develop; eye strain from the effort to read can occur; and itching. The condition is not painful.
Another symptom is seeing multiple “ghosting” images. Instead of seeing just one image, a person with keratoconus sees many images of the same thing in a chaotic pattern. This pattern does not usually change daily, but it often takes different forms over time. People might see streaking or flaring distortion around light sources or notice the images moving relative to one another in time with their heartbeat.
If keratoconus is suspected, the eye physician will use special tests to diagnose the condition and take a medical history, including any family history of eye disease. An examination using an eye chart with progressively smaller letters will be used, and the physician will examine the eyes. The cornea will be examined to detect irregular astigmatism that might suggest the possibility of keratoconus. If necessary, further testing will be done. The diagnosis will also include determining the degree of curvature of the cornea, thinning of the cornea and review of past eye tests and records.
Corneal Topography
This testing method creates highly-sophisticated computerized maps that are often used to confirm the diagnosis of keratoconus. Doctors have developed very sophisticated software to aid in the diagnosis in patients clinically suspected of having the disease. Repeated topographies may show progression of the disease.
Corneal Pachymetry
OCT (Ocular Coherence Tomography) of the cornea measures the corneal thickness throughout the cornea and determines if the cornea is thin, how thin, and where it is thinnest. This is a highly sensitive test for keratoconus and its progression.