![]() Inferior steepening, skewed axis, or elevated keratometry values on K reading and computerized corneal topography.Scissoring of the red reflex on retinoscopy.Keratometry showing high astigmatism and irregularity (the axis that does not add to 180 degrees).Asymmetric refractive error with high or progressive astigmatism.Keratometry/Computerized Topography/Computerized Tomography/Ultrasound Pachymetry.Slit-lamp biomicroscopy of the anterior segment including lid tightness and papillae in upper tarsal conjunctiva.Retinoscopy to check for scissoring reflex.Measurement of best-corrected visual acuity with spectacles and hard or gas permeable contact lenses (with refraction when indicated).Measurement of visual acuity with current correction (the power of the present correction recorded) at distance and when appropriate at near.Measurement of uncorrected visual acuity.Many of the potential exam components are listed below: The best potential vision should also be evaluated. The general health of the eye should be assessed, and appropriate ancillary tests should be done to assess corneal curvature, astigmatism, and thickness. Another common progression is from soft contact lenses to toric or astigmatism correcting contact lenses, to rigid gas permeable contact lenses. A complete ocular and medical history should be taken, including change in eyeglass prescription, decreased vision, history of eye rubbing, medical problems, allergies, and sleep patterns.Ī thorough and complete eye exam should be performed on any patient suspected of having keratoconus. There is often a history of frequent changes in eyeglasses prescription that do not adequately correct vision. There is a variable progression for each individual. However, cases may begin much earlier or later in life, and progression may also persist beyond the 30's. Onset is typically in early adolescence and progresses into the mid-20’s and 30’s. The less affected eye may show a high amount of astigmatism or mild steepening. The majority of cases of keratoconus are bilateral, but often asymmetric. These devices may allow better screening of patients for prospective refractive surgery. New algorithms using computerized videokeratography have been devised which now allow the detection of forme fruste, subclinical, or suspected keratoconus. Ultrasound pachymetry can also be used to measure the thinnest zone on the cornea. Computerized videokeratography is useful in detecting early keratoconus and allows following its progression. In some patients, avoidance of allergens and treatment of ocular surface disease may help decrease eye irritation and therefore decrease eye rubbing.ĭiagnosis can be made by slit-lamp examination and observation of central or inferior corneal thinning. Patients should be informed not to rub their eyes. sleeping with the hand against the eye) can cause and/or lead to the progression of keratoconus. Some feel that eye rubbing or pressure (eg. No preventive strategy has been proven effective to date. Although keratoconus does not fulfill the criteria for inflammatory disease, recent studies show a significant role of proteolytic enzymes, cytokines, and free radicals (MMP-9, IL-6, TNF-α) even in subclinical disease, showing a quasi-inflammatory characteristic in keratoconus. While a genetic predisposition to keratoconus is suggested, a specific gene has not been identified. The etiology of these changes is unknown, though some suspect changes in enzymes that lead to the breakdown of collagen in the cornea. Histopathology studies demonstrated breaks in or complete absence of Bowman’s layer, collagen disorganization, scarring, and thinning. ![]() The American Academy of Ophthalmology's Pathology Atlas contains a virtual microscopy image of Keratoconus. Keratoconus can show the following pathologic findings fragmentation of Bowman’s layer, thinning of stroma and overlying epithelium, folds or breaks in Descemet’s membrane, and variable amounts of diffuse corneal scarring. Eye rubbing, associated with atopy or vernal keratoconjunctivitis.The prevalence of keratoconus if often reported to be 1 in 700. The hereditary pattern is neither prominent nor predictable, but positive family histories have been reported. However, it is associated with atopy, Down’s Syndrome, Leber’s congenital amaurosis, and Ehler’s Danlos/connective disorders. Keratoconus is an uncommon corneal disorder where the central or paracentral cornea undergoes progressive thinning and steepening causing irregular astigmatism.Įtiology is unknown.
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