KNOW YOUR EYE
The human eye has 3 coats, the outermost of which is protective fibrous layer, the sclerocorneal layer. The sclera is the white of the eye. Placed in the front of the sclera, like a watch glass, is the CORNEA
The cornea is a transparent structure and the window through which we see the world. It accounts for a major part of the refractive power of the eye and is primarily responsible for focusing light rays on to the retina of the eye. God has blessed us with a number of mechanisms to maintain the transparency and clarity of the cornea. Any modification by disease process or abnormal stress can cause loss of transparency of the cornea leading to blurring or loss of vision.
The diseases which affect the cornea and cause loss of transparency include Corneal Infections, Corneal degenerations and dystrophies )opacification of cornea caused due to genetic disorders or heredity( and corneal thinning disorders like Keratoconus. Injuries ( mechanical trauma / surgery or chemical/ acid / alkali burns) are also one of the most common causes for Corneal blindness.
When the eye is too long, light focuses in front of the retina causing myopia (Short Sight). When the eye is too short, light rays focus behind the retina causing hyperopia (long sight). When the cornea is shaped like the back of a spoon, light focuses on more than one point and a blurred image is formed on the retina and this is known as astigmatism (Cylindrical power) and is often associated with short sight or long sight.
A corneal ulcer is an open sore in the cornea. It is usually produced by an infection, commonly bacterial, fungal or viral. The ulcer can either be located in the centre of the cornea and greatly affect the vision or be placed in the periphery and not affect it so much. There are at least 25,000 cases of bacterial and fungal corneal ulcers each in India every year. Infections that develop in the cornea are frequently associated with trauma, contact lens overuse and dry eyes. It causes pain, redness and watering in the eye which can be quite severe. Ulcers frequently require 2-3 months of intensive treatment with eye drops and / or tablets and heal by corneal scarring. If visual loss occurs, this may require corneal grafting later in future. If medical treatment fails; intense suppuration) pus formation (often ensues, and the cornea can eventually perforate. Hence non healing ulcers may require therapeutic corneal grafting to save the eye
Fungal corneal infections frequently occur because of trauma with vegetable matter. Viral corneal infections often occur spontaneously or in immunocompromised patients. Collagen vascular disorders like rheumatoid arthritis and systemic diseases like tuberculosis, leprosy, syphilis, diabetes and AIDS can also cause corneal ulcers.
various degenerative conditions like band keratopathy, spheroidal degenerations, lipid keratopathy etc, can cause decrease in vision and require corneal grafting
These are hereditary disorders of cornea which cause excessive production of materials which get deposited in the cornea. If excessive, they can cause visual impairment requiring corneal grafting/ laser treatment )PTK( for vision improvement
Bullous keratopathy & fuch's endothelial dystrophy (fed)
These are diseases of innermost layer of cornea, which can require corneal grafting for visual improvement.
Abnormal endothelium in FED
Keratoconus is a disease where the cornea becomes thinner than normal, and subsequently starts bulging forwards. This causes a blurring of visual images and is a known progressive condition. It is a disease of youngsters, starts in the second decade and is commoner with childhood eye allergy and rubbing habit. It causes frequent change of glasses with increase in cylindrical power. Keratoconus is treated in earlier stage with semi-soft contact lenses, but such lenses would not slow the disease process.
Now, there are a lot of advances in keratoconus treatment. One of the recent treatments is Corneal Collagen Cross-linking with Riboflavin )C3R(, which is a procedure that aims to stabilize a keratoconic cornea. Kerarings are implantable rings inserted into the cornea to flatten the corneal cone, and thus, also helps to improve vision of the patient. We can even put special Implantable contact lenses called Toric ICL to improve vision further in these cases.
For advanced Keratoconus, we can perform Deep Lamellar Keratoplasty or Penetrating Keratoplasty. (Corneal Grafting)
Lasik cannot be done in Keratoconu.
Injury to the cornea is potentially blinding, and may be minor such as a small superficial foreign body, or major, such as acid / alkali )lime( burns or penetrating injury. emergency treatment is mandatory in any kind of injury to the eye. for chemical injuries, one should immediately wash eyes thoroughly with plenty of water for half an hour and immediately see an eye doctor.
Wavefront Lasik or Customized Lasik
Wavefront Lasik or Customized Lasik is the result of a quantum leap in technology of sight restoration and enhancement. This Wavefront guided Lasik is a giant step forward from conventional Lasik. Optical aberrations (imperfections) inherent in the eye may adversely affect the visual acuity and the optical performance of the eye. Conventional Lasik can only correct the spectacle power & not these subtle optical aberrations. With Wavefront
guided Lasik, it is now possible to reduce these aberrations and enhance vision much above the normal levels. Custom Vue (VISx star S4 from AMO) is the procedure available for customized Lasik.
Ocular Surface Tumors
Ocular surface squamous neoplasia )OSSN( is a frequently misdiagnosed eye cancer. If neglected for too long can spread to other parts of body. It requires early detection and surgical excision. Limbal dermoid is a benign tumor which frequently requires excision.
Corneal grafting, medically termed Keratoplasty, is an operation where a diseased cornea is replaced by a clear cornea donated by another person after death. Keratoplasty is of 2 types, Full-thickness and Partial-thickness lamellar.
Full thickness Penetrating Keratoplasty gives satisfactory results but requires a lot of care after surgery. Stitch removal starts after 5-6 months and visual rehabilitation takes between 6 months to 1 year. Strict follow-up is required for first 6 months. Rejection and infection needs to be guarded against. Glasses or contact lenses are required after stitches removal for visual improvement.
Of late, the results of full-thickness keratoplasty also have undergone vast improvement, due to the arrival of the Intralase equipment )Femtosecond laser( which is able to create a precise cut in both donor and recipient )patient's( cornea. This is called IEK, i.e. Intralase Enabled Keratoplasty . It helps in faster visual rehabilitation, better fitting of graft, stronger healing and lesser glass power post operatively. IELK )Intralase enabled lamellar Keratoplasty( is a sutureless topical procedure performed with the same laser machine, which in cases of corneal dystrophies and superficial corneal opacities gives gratifying results. Deep lamellar Keratoplasty is a recent method of corneal grafting where the superficial corneal layers are only replaced, and the endothelium of the patient is retained. The rejection rate of DLK is lesser than conventional full-thickness keratoplasty and success rate is higher.
Decemet's stripping automated endothelial keratoplasty (DSAEK) with fentosecond laser is suture less & quick alternative for the penetrating keratoplasty for endothelial diseases.
Unlike PK, preoperative glass power of patient's eye does not deviate much postoperatively in DSAEK.
Investigative modalities to help in diagnosis of corneal conditions include specular microscopy, which gives a clear picture of the innermost layer of cornea called endothelium. Specular microscopy is especially important in corneal grafting.
Dry eye syndrome is a very common condition affecting many people. It can manifest in numerous ways, such as burning sensation, pricking sensation, redness, feeling of heaviness in eyes, intolerance to contact lenses etc. Dry eyes are diagnosed by examining the tear film of the eye, and with a test called Schirmer's test. Schirmer's test is a test in which the production of tears is measured, and depending on the results, dry eye is treated. Dry eye patients may have associated general diseases, like arthritis, thyroid disease, Diabetes, chronic backache, chronic acidity and Polycystic Ovarian Disease etc. Severe dry eye cases like Steven Johnson's syndrome, Ocular pemphigoid etc. can have corneal opacification and visual loss, which may require immuno suppressive agents and keratoprosthesis.
- Facilities Available in the cornea department of Nethradhama:
- Specular microscopy
- Anterior segment digital photography
- Orbscan II Corneal topography
- Ultrasound pachymeter
- Pentacam ( oculyser )
- Intralase enabled keratoplasty (IEK / IELK)
- Artificial anterior chamber
- maintainer enabled endothelial
- Keratoplasty DSAEK
- Smart plugs for dry eyes
- Corneal tattooing.
- Eye Bank 24 Hrs Services