In keratoconus, a corneal transplant is avoided until the cornea becomes dangerously thin or when sufficient visual acuity to meet the individual’s needs

What Causes Keratoconus?


The exact cause of keratoconus is unknown. It is believed that genetics, the environment and the endocrine system all play a role in keratoconus.







Genetic Causes:

Keratoconus may be genetic because there does appear to be a familial association. There is less than a one in ten chance that a blood relative of a keratoconic patient will have keratoconus. The majority of patients with keratoconus do not have other family members with the disease. Some studies show that keratoconus corneas lack important anchoring fibrils [sugars bind improperly to proteins] that structurally stabilize the anterior cornea. This increased flexibility allows that cornea to “bulge forward” into a cone-shaped appearance.





Irregular curvature of the cornea:


Keratoconus can cause visual distortions because the cornea is not round. Common symptoms are: ghosting, multiple images, glare, halos, starbursts around lights and blurred vision.   A progressive corneal disease characterized by central thinning and steepening of the corneal curvature leads to increased myopia and irregular corneal astigmatism. Five criteria are listed for the detection of keratoconus: 1) apex of the cone is not centered at the 6-o’clock semi-meridian, 2) cone should appear round on the tangential map, 3) keratometry >45.00 diopters, 4) corneal thickness at the apex of the cone is approximately 30 microm thinner than the corresponding distance above the pupil center, and 5) topographic patterns are not symmetric. {Holladay}



Symmetrical Astigmatism: 




Abnormal Topography -Keratoconus with lack of symmetry:



Environmental Causes: Allergies/ Eye Rubbing:

Many who have keratoconus report vigorous eye rubbing and also have allergies (which cause eye itching and irritation, leading to eye rubbing), however the link to allergic disease also remains unclear. A higher percent of keratoconic patients have atopic disease than the general population. Disorders such as hay fever, eczema, asthma, and food allergies are all considered atopic diseases.



Oxidative Stress:

Some studies indicate an abnormal processing of the superoxide radicals in the keratoconus cornea and an involvement of oxidative stress in the pathogenesis of this disease. Keratoconus corneas lack the ability to self-repair routine damage easily repaired by normal corneas. Like any tissues in the body, the cornea creates harmful byproducts of cell metabolism called free radicals. Normal corneas, like any other body tissue, have a defense system in place to neutralize these free radicals so they don’t damage the collagen, the structural part of the cornea, weakening it and causing the cornea to thin and bulge. The keratoconus corneas do not possess the ability to eliminate the free radicals so they stay in the tissue and can cause structural damage.



Keratoconus Treatment:


Contact Lenses for Keratoconus:

Keratoconus is managed by many different contact lens designs.



No one design is best for every type of keratoconus. Since each lens design has its own unique characteristics, Dr. Duplessie carefully evaluates the needs of the individual situation to find the lens that offers the best combination of visual acuity, comfort and corneal health.






Intacs Surgery for Keratoconus :






Intacs is the trademark name for micro-thin plastic inserts which were previously used as a form of refractive surgery in the treatment of low levels of myopia or nearsightedness, but has recently received FDA approval for keratoconus. Intacs for Keratoconus. Intacs are thin plastic, semi-circular rings inserted into the mid layer of the cornea. When inserted in the keratoconus cornea they flatten the cornea, changing the shape and location of the cone. The placement of Intacs remodels and reinforces the cornea, eliminating some or all of the irregularities caused by keratoconus in order to provide improved vision.


This can improve uncorrected vision, however, depending on the severity of the KC, glasses or contact lenses may still be needed for functional vision.


Corneal Collagen Crosslinking with Riboflavin (CXL) is a developing keratoconus treatment:

CXL works by increasing collagen crosslinks which are the natural “anchors” within the cornea.


Before and after crosslinking


These anchors are responsible for preventing the cornea frombulging out and becoming steep and irregular.



Corneal Crosslinking System:



During the corneal crosslinking treatment, custom-made riboflavin drops saturate the cornea, which is then activated by ultraviolet light.


This process has been shown in laboratory and clinical studies to increase the amount of collagen cross-linking in the cornea and strengthen the cornea.


Collagen crosslinking is not a cure for keratoconus. The aim of this treatment is to arrest progression of keratoconus, and thereby prevent further deterioration in vision and the need for corneal transplantation. Glasses or contact lenses will still be needed following the cross-linking treatment (although a change in the prescription may be required) but it is hoped that it could limit further deterioration of vision. This procedure, developed at the Technische Universität Dresden, Germany has been shown to slow or arrest the progression of keratoconus in published European studies.


Corneal Transplants:



Although only 15-20% of those with keratoconus ultimately require corneal transplant surgery, for those who do, it is a crucial and sometimes frightening decision.


Dr. Duplessie is a fellowship trained corneal surgeon and has performed hundreds of corneal transplants.



In keratoconus, a corneal transplant is warranted when the cornea becomes dangerously thin or when sufficient visual acuity to meet the individual’s needs can no longer be achieved by contact lenses due to steepening of the cornea, scaring or lens intolerance. Lens intolerance occurs when the steepened, irregular cornea can no longer be fitted with a contact lens, or the patient cannot tolerate the lens