What is Keratoconus ?
Keratoconus is a progressive disease of the cornea affecting young adults mostly in their twenties. It is characterized by progressive thinning of the normally round cornea causing it to bulge forward and assume a cone like shape .This irregularity in the cornea results in the formation of a distorted image of objects on the retina & gives rise to blurred vision. It generally affects both eyes but can also occur unilaterally.
Symptoms and Signs
Keratoconus cases are diagnosed many times only on routine eye examination by the eye practitioner. Keratoconus causes myopia or nearsightedness & astigmatism & the patients experience frequent changes in glasses prescription with fluctuation in vision. Some patients also have glare & sensitivity to light specially during night.
In advanced stage of Keratoconus, even corrective prescription glasses does not help the patient to see clearly and they have to switch to using hard or semi-soft contact lenses.
Your eye care practitioner can diagnose early stage of keratoconus after a detailed eye examination including retinoscopy, slit lamp examination and sophisticated tests like topography to check the shape and curvature of cornea & Pachymetry to determine the thickness of the cornea. What Causes Keratoconus? The exact cause of keratoconus is not known but latest research suggests that the cornea becomes weakened due to imbalance of enzymes within corneal tissue. Young patients produce high level of free radicals which causes oxidative damage to the cornea in the absence of protective enzymes. This causes thinning and bulging of cornea.
Keratoconus also shows some genetic predisposition. It may transmit from parent to children and affect more than one family member. It is also associated with excessive eye rubbing as it is more common in allergic conjunctivitis patients who have itching and tend to rub their eyes very often. Other risk factors are overexposure to ultra violet rays, chronic eye irritation and improperly fit contact lenses. Treatment option for Keratoconus In early stages, when the cornea is still regular, corrective prescription glasses or soft contact lens can help the patients. As keratoconus advances the corneal surface becomes increasingly irregular and these options do not help adequately.
In intermediate stage, various treatment options are different type of contact lenses available.
Rigid Gas Permeable Contact Lenses:
They are the first choice of treatment when glasses fail to help the patient. They provide a smooth refractive surface replacing the irregular cone like surface of the cornea , thus enabling the patient to see clearly.
Lens fitting in keratoconus can be a demanding and time consuming process. It requires frequent visits to the eye doctor to get a perfect and comfortable fit. RGP lenses are not as comfortable as soft contact lenses.
“Piggybacking” Contact Lenses:
Some eye doctors practice “piggybacking” where a soft contact lens is first placed on cornea to give it a cushion like effect and on top of it RGP lens is fitted. Thus, it combines the best features of both lenses in the sense that it makes the wearer comfortable and at the same time gives crisp vision. The fitting should be perfect to ensure good oxygen permeability to the cornea as the patient will be wearing two lenses. However, with newer high oxygen permeable lenses this is not a problem.
Hybrid Contact lenses:
Some manufacturers have come up with this unique design of contact lenses where the central visual portion is made up of high oxygen permeable rigid material and peripheral anchoring portion is of soft hydrogel material. This also maximizes the best feature of both lenses and improves wearers comfort as well as visual performance in keratoconic eyes.
In the last decade, with newer technological advances in treatment modalities for keratoconus, INTACS and C3-R have showed promising & encouraging results. INTACS Intacs are plastic insertable devices approved by FDA in 2004 for treatment of keratoconus and myopia upto 3 dioptres. These semicircular rings of various thickness are placed within the inner layers of the cornea. Their placement remodels and reinforces the cornea, eliminating all or some of its irregularity caused by keratoconus. At the same time it flattens the cornea, correcting the myopic & astigmatic refractive error to a considerable extent.
Intacs placement is a simple procedure and does not require any tissue removal. They are reversible and cannot be felt by the patient after insertion and healing. They require no maintenance. However, glasses or contact lenses may be required even after successful intacs implantation. They have shown to improve vision and stop progression of keratoconus, thereby saving the patient from requiring corneal transplantation. To Know more click here
C3-R Treatment (Corneal Collagen Cross Linkage with Riboflavin)
It is a non-invasive and very popular procedure for treatment of keratoconus. It strengthens the collagen tissue which forms the fabric of cornea. This is simple 60 minutes in-office procedure. Eye drops containing Riboflavin (Vitamin B2) are put on the cornea and then activated by Ultra-violet light. This increases the collagen cross linking causing strengthening of cornea thereby stopping it from bulging outwards and arresting keratoconus from progression.
In the 3 years results of clinical study in human eyes, C3-R treatment has shown arrest of progression of keratoconus in all treated patients. C3-R procedure changes intrusive bio-chemical properties of the cornea increasing its strength by almost 300%. To Know more click here Keratoplasty It is the last option when all the above methods do not help patients to get optimum useful vision. In this procedure the cornea which forms the transparent outer covering of the eye is replaced by a donor cornea. It is an intra ocular surgery and requires long term healing and consistent follow-up. Sometimes it shows unpredictable results and may require a repeat surgery. Even after a successful transplant, glasses or contact lenses may be required to give useful clear vision.