Cornea

Cornea

The outermost transparent part of the eye is the cornea. It contributes 70% of the focusing power of the eye. It measures about 12 mm wide and 11 mm height. That is the main reason why it is imperative to take care of your cornea.

Epithelium – Gatekeeper of the eye

It is the outermost layer of the cornea which means that whatever external objects will come in contact with the eyes, they will have to pass the epithelium. It keeps away dust, debris and bacteria. It absorbs nutrients and oxygen from tears.

Bowman’s Layer – Guardian of the eye

It is also known as anterior limiting membrane and is made up of protein fibers which are called collagen. It is a strong layer that is between the epithelium and the corneal stroma and is built to protect the stroma

Stroma – Transparency

It is the middle layer of the cornea and contributes towards around 90 per cent of the overall thickness of the cornea. It comprises mainly collagen fibrils and water along with interconnected keratocytes which are used for the repair and maintenance of the cornea. There are 200 to 300 layers of collagen fibrils arranged in a parallel manner, and this is the main reason that enables the cornea to be entirely transparent

Descemet’s Membrane – Armor the eye from Injury/ infection

It is the fourth layer of the cornea which is quite thin but very strong as it helps protect against any infections or injuries. It is also known as a posterior limiting membrane. It is also made up of collagen fibrils and separates the stroma from the corneal endothelium.

Endothelium – Maintains the Fluids

It is the final layer of the cornea which is in the innermost part. It is made up of mitochondria-rich cells. Bathed by aqueous humour, the endothelium’s primary function is to keep a perfect balance between the fluids flowing in and out of the cornea at all times. It is the layer that comes directly in contact with the iris and pupil of the eye.

What are the common corneal problems?

Most commonly seen corneal problems include refractive error, bullous keratopathy, keratoconus, ocular surface diseases, corneal ulcers and allergic keratoconjunctivitis. Refractive surgery is a cosmetic surgery that is performed to enjoy a spectacle-free life. It is the second most common surgery performed after cataract surgery. To know more about refractive surgery–>

DRY EYES

Dry eye is an emerging silent pandemic that occurs due to either excessive evaporation of tears or insufficient production of tears. We, at Madurai eye Centre, have the latest diagnostic equipment and the expertise to provide the best treatment solution for dry eyes. To know more about dry eye –>

CORNEAL ULCER

A corneal ulcer is an open sore that develops on the cornea. Common causes of corneal ulcers are viral, fungal, bacterial & parasitic infections.

Corneal Ulcer Evaluation

• Visual acuity test

As a part of the corneal ulcer evaluation, visual acuity is checked every visit. This allows our expert to assess the present status and follow the progression of the disease.

• Slit-lamp Biomicroscopy and Photography

  Our specialists evaluate every patient on a slit-lamp, which is a device that helps to magnify and view the area of interest. We measure the ulcer size at every visit and take photographs which helps to compare with previous visits and also explain to the patient about his current eye condition.

• Microbiological Test

  It is of utmost importance to know the cause of the corneal ulcer. As a part of an assessment protocol, cornea specialists scrape the part of the ulcer and send it to the laboratory for evaluation. The idea behind this test is an in-depth analysis of causative organisms and sensitivity to assess testing for appropriate drug therapy. We have an association with NABL accredited microbiological laboratory to arrive at identifying the causative organism with advanced technologies like PCR and immunofluorescence.

Medical Management of Corneal Ulcer

After identifying the microorganism responsible for the eye infection, our specialists start the treatment according to the drug sensitivity report. We will assess the progress and modify treatment if needed.

Surgical Management of Corneal Ulcer

In case of failure of conservative & medical management, the surgical treatment ensures eye integrity is the mainstay of the treatment in case of impending perforation. Surgical treatment includes applying tissue adhesive in impending perforation to full-thickness or partial-thickness corneal transplant depending on the corneal perforation.

 

KERATOCONUS

Keratoconus is a progressive degenerative disorder of the cornea. In this condition, the cornea bends forward resulting in a conical shape, unlike the natural curvature of the cornea. This conical distortion in the shape of the cornea prevents focusing the light on the retina resulting in irregular astigmatism with compromised visual acuity. In the advanced stages, there will be significant thinning of the cornea which might need corneal transplantation.

 

CORNEAL TRANSPLANTATION

Cornea is the transparent part of the eye through which light enters the retina for clear vision. Cloudiness in the cornea can affect vision. A corneal transplant surgery also called Keratoplasty involves surgical removal of the diseased cloudy cornea (full or partial thickness) with a healthy transparent donor cornea (full or partial thickness). This improves vision in those who have blurry vision due to a corneal disease following trauma or infection or congenital or genetic corneal disorder.

Types of Corneal Transplant

Cornea transplantation can be full thickness or partial thickness. The choice of procedure is dependent on the patient’s corneal disease.

Penetrating Keratoplasty

When the cornea is scarred in all the layers then a full-thickness transplant called penetrating keratoplasty is done whereby all the layers of the patient’s cornea are replaced by donor cornea and sutured in place.

Deep Anterior Lamellar Keratoplasty (DALK)

Anterior Lamellar Keratoplasty is a type of partial-thickness corneal transplant surgery that is done to replace the anterior diseased corneal tissue with healthy and transparent donor tissue. In conditions like keratoconus, corneal dystrophy, and scars where only the front part of the cornea is involved, DALK procedure is done to replace it with a healthy transparent donor cornea, This corneal transplant surgery aims to preserve the back part of the cornea. This process has few sutures and has lesser chances of rejection by the patient’s immune system.

Endothelial Keratoplasty

This is a highly specialized surgery wherein only the diseased back layer of the cornea is replaced with a healthy donor corneal endothelial layer. In conditions like post-cataract surgery corneal edema where only the back layer of the cornea is damaged, only the back layer is replaced with the donor’s corneal back layer in a procedure called Descemet’s stripping endothelial keratoplasty. This means replacing only diseased corneal layers and leaving behind an intact anterior (front part) cornea which leads to faster visual rehabilitation. This procedure reduces the risk of rejection and eliminates the need for sutures.

What will be the visual rehabilitation after corneal transplant surgery?

Vision may keep changing for a few months or even up to a year during the course of recovery. Once the outer layer of your cornea has healed — several weeks to several months after surgery — your eye doctor will work to make adjustments that can improve your vision, such as:

• Correcting unevenness in your cornea (astigmatism). The stitches that hold the donor cornea in place on your eye might cause dips and bumps in your cornea, making your vision blurry in spots. Your doctor might correct some of this by releasing some stitches and tightening others.
• Correcting vision problems. Refractive errors, such as nearsightedness and farsightedness, can be corrected with glasses, contact lenses, or, in some cases, laser eye surgery.

What are the complications we can expect after a corneal transplant?

A cornea transplant is relatively safe. Still, it does carry a small risk of serious complications, such as:

• Eye infection
• Pressure increase within the eyeball (glaucoma)
• Problems with the stitches used to secure the donor cornea
• Rejection of the donor cornea
• Bleeding
• Retinal problems, such as retinal detachment or swelling

It is prudent to report immediately when you have sudden blurry vision and get checked with our corneal surgeon to identify if there is any issue like infection or graft rejection and you will be prescribed medications accordingly. It is also important to check the sutures and get scans done at subsequent visits to assess the refractive status of the eye