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Posts Tagged ‘cornea disease’

An Introduction to Keratoconus

Friday, July 30th, 2010

Keratoconus in an eye disease that is characterized by thinning and steepening of the cornea. The cornea is the front surface of the eye and the most important focusing element of the vision system. In patients who have keratoconus their cornea is cone shaped. The name keratoconus is derived from the Greek word for cornea (‘kerato’) and cone shaped (‘conus’). Keratoconus results in visual distortion often not correctable by traditional glasses. The thinning and steepening of the cornea causes the front surface to become progressively more irregular in shape. The corneal surface irregularity is what induces the distortion and blurriness of vision experienced in keratoconus.

Keratoconus Conical Cornea

Keratoconus Conical Cornea

Keratoconus is found in approximately one in two thousand individuals, and as such can be considered a relatively common eye disease. New, more sensitive diagnostic techniques will likely increase the prevalence rates of keratoconus found in future studies. There is strong evidence that keratoconus has a genetic basis. Though studies have shown variable rates of keratoconus among family members of patients with the disease, it is felt that significant genetic components do exist. There is virtually no gender predilection in keratoconus with equal incidence in males and females. Typically keratoconus is initially diagnosed just after puberty and can progress through the third to fourth decade of life, however individual cases can present at any age and progress throughout life. Keratoconus most often is found in both eyes, but commonly more advanced in one versus the other. Cases of true unilateral (one eye only) keratoconus do exist, however they are the rare exception to the rule.

Commonly reported risk factors for keratoconus include: atopic allergic disease (when someone is highly sensitive to allergens), especially a history of eye allergies, and vigorous eye rubbing. The severity of the disease is quite variable. Some cases develop only to a mild stage and do not progress further. Patients with this form of the disease often can achieve adequate vision correction with the use of glasses or soft contact lenses. Other cases may progress significantly and result in dramatic distortion of vision which requires treatment with specialized contact lenses (typically rigid gas permeable, hybrid, or scleral lenses). The most advanced cases of keratoconus can develop corneal scaring and require surgical corneal transplantation. New medical technologies such as collagen corneal cross-linking with riboflavin hold promise for controlling progressive cases of keratoconus.

Author: S. Barry Eiden, OD, FAAO

President and Medical Director of North Suburban Vision Consultants, Ltd.

Website: http://www.nsvc.com

EyeVis Eye and Vision Research Institute

Immediate Past Chair of the Contact Lens and Cornea Section of the American Optometric Association



READ “How is Keratoconus Diagnosed?”

Surgical Treatment Options for Keratoconus

Tuesday, July 27th, 2010

Medical and surgical options for the treatment of keratoconus are also expanding and improving. Corneal transplantation (penetrating keratoplasty or “PK”) has been utilized for the surgical management of keratoconus for many decades. The criteria for PK surgery typically is either the development of corneal scaring that reduces best corrected vision (even with contact lenses) or intolerance to contact lens wear (due to poor comfort or the inability to achieve a stable fit). Modification and improvement in surgical techniques has made PK much more successful. It should be noted however that keratoconus patients undergoing PK most often still require contact lenses to provide optimal vision. It is the exception to the rule to find patients who do not need some form of contact lens correction following PK, and even rarer to find a patient who does not need any type of vision correction after this surgery.



Intacs Corneal Segments

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Intacs (by Addition Technology) is a relatively newer surgical method to address the corneal irregularity found in keratoconus. It involves the implantation of tiny plastic segments within the cornea. The result is to make the optical surface of the cornea relatively more regular, thus reducing the degree of vision distortion. This technology is only indicated for keratoconic corneas without scaring, yet have become contact lens intolerant. Results with Intacs have been encouraging, but once again are not a total solution for this disease. As with PK, patients who have had Intacs implanted most often still require contact lens correction for maximum vision. By making the corneal surface more regular contact lens fitting may be more successful following Intacs.

The newest development in the medical treatment for keratoconus is termed “Collagen Crosslinking with Riboflavin”. It involved the exposure of the cornea to riboflavin (vitamin B2) and ultraviolet light for a period of time. The result is a change in the crosslinking of collagen fibrils within the substance of the cornea. For some patients this treatment strengthens the cornea and therefore slows down or halts the progression of keratoconus. For some more fortunate patients this treatment may also improve corneal surface regularity. Numerous studies evaluating this so far non-FDA approved procedure are going on throughout the United States.

Keratoconus is a corneal disease that results in progressive visual distortion. Technologies in contact lens correction, medical treatment, and surgical options for keratoconus continue to improve. The primary treatment for the disease is with specialized contact lenses. Seeing an eye care professional who is skilled and experienced in the diagnosis and management of keratoconus provides the best opportunity to experience the best vision possible.

Article Written by: S. Barry Eiden, OD, FAAO

President and Medical Director of North Suburban Vision Consultants, Ltd.

Website: http://www.nsvc.com

EyeVis Eye and Vision Research Institute

Immediate Past Chair of the Contact Lens and Cornea Section of the American Optometric Association


« READ “Non-Surgical Treatment Options”

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