CORNEAL DISEASES AND TREATMENTS
Infectious Keratitis (corneal ulcer)
Microbial keratitis continues to be a leading cause of ocular morbidity and blindness
worldwide, more so in developing countries. Its annual incidence is reported to be 11.3 pe r
10,000 people in India.
Some common factors contributing to the increased prevalence are ocular trauma, contact
lens wear , coexisting ocular diseases , diabetes mellitus, leprosy and injudicious use of
A 'dry eye' is a condition where patients suffer from irritation and discomfort in the eye
because of the decreased quantity of tears or increased evaporation of tears from the eye.
The symptoms are non-specific and can range from a tired or itching eye to diminished
vision in severe cases. A clinical examination can help diagnose a condition of 'dry eyes'
but, to be more definitive, diagnostic tests are required.
The treatment includes use of preservative-free artificial tears, and topical
Dry eyes can also be a manifestation of systemic diseases like rheumatoid arthiritis. A
blood examination could help identify the disease, which can then be jointly treated by the
ophthalmologist and rheumatologist. Patients who have such symptoms are advised procedures
to preserve tears through implantation of silicone punctal plugs or cauterising the puncta
A pterygium is a pinkish, triangular-shaped tissue growth on the cornea. Some pterygia grow
slowly throughout a person's life, while others stop growing after a certain point. A
pterygium rarely grows so large that it begins to cover the pupil of the eye.
Pterygia are more common in sunny climates and in the 20-40 age group. Scientists do not
know what causes pterygia to develop. However, since people who have pterygia usually have
spent a significant time outdoors, many doctors believe ultraviolet (UV) light from the sun
may be a factor. In areas where sunlight is strong, wearing protective eyeglasses,
sunglasses, and/or hats with brims are suggested. Because a pterygium is visible, many
people want to have it removed for cosmetic reasons. It is usually not too noticeable
unless it becomes red and swollen from dust or air pollutants.
Pterygium excision is not recommended unless it affects vision. If a pterygium is
surgically removed, it may grow back, particularly if the patient is less than 40 years of
age. Lubricants can reduce the redness and provide relief from the chronic irritation.
Keratoconus arises when the middle of the cornea thins and gradually bulges outward,
forming a rounded cone shape. It is a progressive disorder affecting one in every 2,000
Indians and is more prevalent in teenagers and adults in their 20s. This abnormal
curvature changes the cornea's refractive power, producing moderate to severe distortion
(from astigmatism) and blurriness (from nearsightedness) of vision. Keratoconus may also
cause swelling and a sight-impairing scarring of the tissue.
Keratoconus usually affects both eyes. At first, people can correct their vision with
eyeglasses. But as the astigmatism worsens, they must rely on specially fitted contact
lenses to reduce the distortion and provide better vision. It can also cause increased light
sensitivity and glare. Although finding a comfortable contact lens can be an extremely
frustrating and difficult process, it is crucial because a poorly fitting lens could further
damage the cornea and make wearing a contact lens intolerable. ROSE K are specialized lenses
are meant for patients who are unable to adjust to RGP contact lenses.
A new non surgical, non invasive treatment, based on collagen cross linking with Ultraviolet A (UVA, 365nm)
and riboflavin (Vitamin B 2), a photosensitizing agent is now available for treating
keratoconus. This changes the intrinsic biomechanical properties of the cornea, increasing
its strength by almost 300%. This increase in corneal strength has shown to arrest the
progression of keratoconus in numerous studies all over the world.
What is Corneal Transplantation?
Corneal transplantation is a procedure in which diseased cornea is surgically removed and
replaced with a healthy one to restore clear vision.
The cornea is the front, outermost layer of the eye. Just as a window lets light into a
room, the cornea lets light into the eye. It also focuses the light passing through it to
make images clear and sharp.
Corneal problems can occur in anyone regardless of age. Sometimes due to disease, injury
or infection the cornea becomes cloudy or warped. A damaged cornea, like a frosted or
misshapen windowpane, distorts light as it enters the eye. This not only causes distortion
in vision, it may also cause pain.
Stem cell and buccal mucosal transplantation
Stem Cell Transplant for Ocular Surface Diseases
The ocular surface comprises the corneal epithelium and the conjunctival epithelium covering
the cornea and front surface of the eye. Ocular Surface Diseases (OSD) are the result of
injuries to or cell deficiency of the corneal epithelium and conjunctival epithelium,
causing blindness. Direct causes include chemical and thermal burns, trachoma and Stevens
Previously, treating OSD with conventional corneal transplants was not very successful
because the Limbal Stem Cells (source of healthy corneal epithelium) and Conjunctival Stem
Cells were not being transplanted at the same time.
Thanks to pioneering methods and new surgical techniques, transplanting both Limbal and
Conjunctival Stem Cells is now part of the procedure, contributing to the success of the
corneal transplant in cases of OSD. To prevent rejection, patient's own limbal and
conjunctival stem cells are cultured in Aravind Eye Hospital,s own GVERI Stem Cell
Laboratory and these cells are retransplanted back into the patient's own eye after 2 weeks.
With this method, transplant rejection is avoided and success rates are far higher than
using stem cells from other donors.
Patients with severe ocular surface damage are advised to undergo limbal stem cell
transplantation for the restoration of the ocular surface and the improvement of visual
Amniotic membrane transplantation
Amniotic membrane transplantation is currently being used for a continuously widening
spectrum of ophthalmic indications. It has gained widespread attention as an effective
method of reconstruction of the ocular surface. Amniotic membrane obtained from human
placenta in a sterile technique has a unique combination of properties, including the
facilitation of migration of epithelial cells, the reinforcement of basal cellular adhesion
and the encouragement of epithelial differentiation. Its ability to modulate stromal
scarring and its anti-inflammatory activity has led to its use in the treatment of ocular
surface pathology as well as an adjunct to limbal stem cell grafts. Amniotic membrane
transplantation has been used for reconstruction of the corneal surface in the setting of
persistent epithelial defects, partial limbal stem cell deficiency, bullous keratopathy and
corneoscleral ulcers. It has also been used in conjunction with limbal stem cell
transplantation for total limbal stem cell deficiency. Amniotic membrane grafts have been
effectively used as a conjunctival substitute for reconstruction of conjunctival defects
following removal of pterygia, conjunctival lesions and symblephara. More recently, amniotic
membrane has been used as a substrate for ex vivo cultivation of
limbal, corneal and conjunctival epithelial cells
The Keratoprothesis is an artificial cornea that can be used after standard corneal
transplant has failed or when such a transplant would be unlikely to succeed. Thus
keratoprosthesis implantation is a procedure designed to help blind patients whose
conditions are the most difficult to treat.
The Boston Keratoprosthesis has been under development since the 1960s and has been
gradually improved. It received FDA clearance in 1992. More than 3,000 implantations have
been performed (January 2009). It is the most commonly used artificial cornea in the United
States and in the world.
The keratoprosthesis is made of clear plastic with excellent tissue tolerance and optical
properties. It consists of three parts and when fully assembled, has the shape of a
The device is inserted into a corneal graft, which is then sutured into the patient’s
cornea as in standard transplantation. If the natural lens is in place, it is also
removed. Finally, a soft contact lens is applied to the surface; it must be worn around the
clock, everyday. This does not cause any discomfort.
Our one-step surgery is simpler and faster than procedures used in other
keratoprosthesis models; it generally requires about one and one half hours to
complete. While general anesthesia is recommended, the recent trend is for performing
the surgery under local anesthesia with intravenous sedation. Visual improvement is usually
seen the following day or week(s). Although the prosthesis is clear, use of a colored
contact lens can perfectly match the iris color of the opposite eye.
Stability and Safety
The Boston Keratoprosthesis is known for excellent long-term (many years) stability and
safety. Its optical system can provide normal vision if the rest of the eye is undamaged.
The surgery is reversible at any time.