What is Cornea?

The cornea of the eye is the outermost transparent layer of the eye which covers the iris and the pupil.
For example, it is like the clear glass placed on the dial of our watch.
The main job of the cornea is to help the eyes focus. It directs the light rays into the eye and helps them focus on the retina which is at the back of the eye, thus providing clear and sharp vision.


normal eye with clear cornea

Anatomy of the Cornea


  • Layers of the cornea (epithelium, stroma, endothelium)
    The cornea has 5 layers namely: Epithelium: the outermost layer of the cornea is called the epithelium and it prevents any material from entering the eye.
    Bowman’s layer: this layer connects the epithelium and the stroma
    Stroma: the cornea gets its dome shaped due to the stroma. It is the thickest layer of the cornea.
    Descemet’s membrane: it is a thin layer which separates the stroma from the endothelium.
    Endothelium: this is a single layer of cells which is found in between the stroma and the aqueous humor, the aqueous is a clear jelly like substance found in our eye.

Recently a 6th layer called Dua’s layer has been discovered and added to the anatomical knowledge.

  • Corneal shape and transparency
    The cornea is curved and has a dome like shape and it is transparent in nature, just like the glass casing on the dial of a watch.


The cornea of eye Functions

  • Light refraction and focusing
    the cornea functions like a camera lens, it helps to focus the light that comes into our eye onto the retina so that we have clear and sharp vision.
  • Protection of the inner eye
    the cornea acts like a shield and does not let any materials get lodged or enter the inner eye.


How are cornea of eye problems diagnosed?

The Ophthalmologist does a thorough eye examination which includes the slit lamp examination, they can also do an fluorescein eye stain test to check for any scratches or damage visible to the cornea and a corneal topography scan can also be done to check for any surface abrasions or damage to the cornea.

Common Corneal Conditions:

1. Corneal infections

  • Causes, symptoms, and treatment

Commonly caused corneal ulcers/infections happen due to bacteria, virus, parasite.
Most common corneal ulcers/infections happen due to over use of contact lenses, or maybe even sleeping with contact lenses on,  sometimes using homemade contact lens solutions.
Symptoms of corneal infections can include: blurry or hazy vision, eyes may appear red or bloodshot, discharge and itching, very painful eye and white patches on the cornea.
Treatment: on experiencing such symptoms the patient should immediately visit their ophthalmologist to prevent any further damage or scarring to the cornea and once a corneal infection is diagnosed, the doctor will treat it with antibiotics or whatever line of treatment is necessary.

Infections or immune reactions in the cornea are referred to as “Keratitis”. When the infection penetrates to cause breakdown of the intact layers of cornea of eye, it is often referred to as a “CORNEAL ULCER”.

These are usually accompanied by loss/reduction of transparency of the cornea, and hence the primary complaint of a patient presenting with central keratitis would be blurring of vision.

In the case of infections, it tends to take longer time to heal. Appropriate anti-infectives are given in the form of drops or oral medications, to arrest the infectious agent in its early stages.

Occasionally, the keratitis (infection of cornea of eye) may heal with the formation of a scar which may cause persistent hazy vision. Depending on the amount of vision affected, extreme cases may even require a corneal transplant


2. Corneal dystrophy and degeneration

These are relatively rare conditions involving the cornea of eye and may affect one or both eyes. Often they are idiopathic, meaning have no known cause. Typically they cause worsening of vision, and have a tendency to relapse even after they are operated on.

  • Different types and their characteristics

There are more than 20 corneal dystrophies, they are inherited most of the time and they are mostly slow progressing in nature.

The most common corneal dystrophies are:

Fuch’s dystrophy: the cornea swells up and gets very painful and the vision gets distorted.
Management/treatment: the doctor will first try to use saline drops, soft contact lenses, ointments to reduce the swelling and if it still does not help and the condition progresses faster than expected then the patient would have to opt for a corneal transplant.

Granular dystrophy: this condition causes crumb or granule like lesions on the inside of the eye, which over times gets painful and can affect the vision.
management/treatment: treatment for this condition may range from eye drops in the early stages or reduce the erosions to corneal transplant for the latter stages.

Lattice dystrophy: in this condition the stroma gets covered with abnormal protein fibres, overtime they start to converge and take up more or most of the stroma hence affecting the cornea and causing cloudiness and affecting the vision.
management/treatment: this condition mostly leaves people with a scarring on the cornea which causes a permanent haze in the vision which can worsen over time, so a corneal transplant can be done when the vision is affected to a great extent. A PTK (phototherpeutic keratectomy)is a laser based treatment that can also be considered if the scarring/hazing happens on the donor tissue too after the transplant. PTK procedure can help by removing the diseased layer of the cornea.

Map-dot fingerprint dystrophy: in this condition, erosion of the epithelium happens due to it not being developed normally and that leads to changes in the cornea curvature causing blurred vision periodically.
management/treatment: this condition can be initially managed with eye drops or ointments in its early stages. Other treatments such as corneal scraping, ptk can also be done to give relief to the patient.

3. Corneal Injuries

  • Types of injuries

Corneal injuries can be classified broadly as traumatic and exposure related.
Traumatic injuries may include any damage to the surface due to any scratches or abrasions or any foreign body.(such as scratching your eye too hard, having a pencil or finger pushed in your eye unknowingly by mistake).
Exposure related injuries may include burns from radiation, chemical or thermal sources.

  • First aid and medical treatment

Rinse your eye with clean sterile water, then get the patient to visit their ophthalmologist on an urgent basis so that the eye is not  damaged further.

Corneal Transplantation

  • Indications for corneal transplants
    a corneal transplant can be done when there is severe damage to the cornea either from an injury or the preexisting corneal dystrophy has worsened.
  • The transplant procedure and recovery
    During the transplant procedure the diseased layer of the cornea is sliced in a circular form(similar to a cookie cutter) and replaced with healthy donor tissue.
    It can take up to a year to fully recover from a corneal transplant. with the exception of heavy lifting, majority people are back to their normal practices and routine within one to two weeks. Though it is advised to wait at least four weeks before doing any heavy lifting, or longer if your doctor instructs it.

Cornea Care and Hygiene

  • Tips for maintaining corneal health
    Regular checkups with the Ophthalmologist- may require a Specular Microscopy
    wear sunglasses to reduce uv exposure from sun rays
    keep a check on your diabetes and eye health.
  • Contact lens care and safety
    always wash your hands before handling your contact lenses
    use the CRD method while wearing contact lenses
    C=cleanse; R=rinse; D=disinfect and dry with the right contact solution.
    do not sleep with contact lenses on
    do not use your saliva or tap water, or any homemade nonsterile solution to clean your contact lenses.

Lifestyle and Corneal Health

  • Diet and nutrition for healthy eyes
    eat a healthy balanced diet which comprises of a lot of vitamins and nutrients like zinc, copper, vitamin A, vitamin E and vitamin C.
  • Protecting your eyes from environmental factors
    wear sunglasses to protect your eyes from the sun's uv rays
    get a good nights sleep
  • exercises to maintain vision naturally
    blinking the eyes at regular intervals is a good form of exercise for the eyes.
    moving the eyes up, down and sideways is also a good form of exercise for the eyes.

Check out our video on eye exercise on our YouTube channel “Dr Kareeshma Wadia- Jehan Eye Clinic”.

Importance of corneal health and regular eye check-ups:

  • The cornea is the very first layer of our eye. it acts as a barrier and protects the inner eye. It plays a vital role in our vision, hence we must make sure to take care of it in every possible way.
  • Get regular eye checkups done, wear protective eye gear during sports, wear sunglasses to protect the eyes from the suns uv rays.Our eye is an important part of our body and one must not ignore it, regular eye checkups must be done to keep a track of our eye health.
    A simple eye examination can also help detect underlying diseases such a diabetes and cancer.

Dr Kareeshma Wadia has done a super speciality in this field and spent 2 years in Bangalore at Narayana Nethralaya Superspeciality Eye Hospital to master the art of these cornea transplant surgeries.

Corneal infections- Red congested eye with yellowish lesion on the cornea which is the infection

Infection of the eye

Infection of the eye