Description

ABOUT CORNEAL DISEASES

The cornea is the transparent, curved front part of the eye which focuses light, protects the eye against external factors and plays a major role in vision.

Corneal Examination Methods

A person who is not an ophthalmologist can use localized light to evaluate corneal transparency, the brightness of its surface and corneal injuries; and a cotton swab to evaluate corneal sensitivity. Ophthalmologists use some devices to assess corneal morphology and function.

Biomicroscopy: It is used for binocular examination of the cornea and other structures of the anterior segment. Light beams of varying thicknesses are directed from different angles for magnification of the biomicroscope and the cornea can be examined. This is the most common examination method that is used routinely.

Keratometry: Measurement of the cornea’s refractive power. It is used before contact lens and intraocular lens placement.

Topography: It is used for the topographic analysis of the corneal surface.

Pachymetry: Measurement of the corneal thickness.

Specular microscopy: Shows the number and structure of endothelial cells.

Esthesiometry: It is used to assess corneal sensitivity.

Corneal staining: The defects on the corneal surface can be seen through fluorescein and rose bengal staining.

KERATOCONUS

What is Keratoconus? 

Keratoconus is an eye disorder caused by thinning and steepening of the transparent layer of the eye, the cornea, with progressive myopia and astigmatism. Onset of the disease is typically in adolescence, although patients become aware of the condition in their 20s. Keratoconus progresses between the ages of 20 and 40, and enters the stationary phase after the age of 40. The cornea is a very important part of your eye. Light enters the eye through the cornea. The cornea refracts, or focuses, the light rays for clear vision. With keratoconus, the shape of the cornea is altered, distorting vision. Keratoconus can make some activities difficult, such as driving, typing on a computer, watching television, or reading.

What Causes Keratoconus?

Although the exact cause of keratoconus is unknown, genetics and mechanical traumas play an important role in its development. Environmental factors such as eye rubbing and wearing hard contact lenses may cause further progression of the disease in patients with a genetic predisposition.

What are the Disease Symptoms?

• Persistent eye allergy or itching (mild eye irritation)

• Presence of progressive myopia and astigmatism

• Low quality of vision despite eyeglasses

• Increased sensitivity to light

• Glare

These symptoms are indicative of a high risk of keratoconus disease. In such cases, it is recommended that you consult an expert physician for examination since early diagnosis and treatment of keratoconus disease are of great importance to prevent material vision disorders which may subsequently emerge.

Keratoconus is associated with two essential problems;

Decreased vision: Contact lenses are the first choice to correct vision. If the disease is progressive, contact lenses must be fitted after stabilization. If the patient cannot use contact lenses, corneal ring segment implantation, topography-guided laser or intraocular contact lenses are alternative treatments.

Disease progression: CCL (Corneal Cross-Linking) and corneal ring segment implantation are used to stop the progression. These treatments do not improve vision, but hinder the progression of the disease.

CCL (CORNEAL CROSS-LINKING)

The aim of Corneal Cross-Linking (CCL) treatment is to strengthen the corneal structure and stop the progression of the disease.

Application of Riboflavin (vitamin B2) Eye Drops 

Prior to treatment, the eye is anesthetized with topical anesthetic drops. Following topical anesthetic eye drops, the corneal epithelium is removed mechanically using a blunt spatula. 2 drops of riboflavin solution are applied over the cornea without epithelium at 5-minute intervals for 30 minutes.

UV Light Application

After 30 minutes, the patient is placed under a biomicroscope. After the fluorescence of the riboflavin is observed in the anterior chamber, the patient is taken back to the operating room. The cornea is exposed to 370 nm UV light for 5-10 minutes at 4-5 cm distance, within a space of 7 mm. During UV application, 2 drops of riboflavin are applied once every 1 minute. At the end of this procedure, a bandage contact lens is applied to the eye, but the eye is not covered.

UV Cross-Linking (Cross Linking in the Molecular Level) Treatment

UV Cross-Linking can stop the progression of the keratoconus disease by using UVA light and riboflavin to impact the collagen molecules of the cornea thus increasing the biomechanical strengthening of the cornea.

Outcomes of CCL Operations

The first scientific study of Dünyagöz Hospitals regarding this topic was presented at the European Society of Cataract and Refractive Surgeons (ESCRS, 8–12 September 2007) in Stockholm and approved to be presented at the American Academy of Ophthalmology (AAO) Congress.

Pre-Operative Tests and Examinations

• Level of vision with and without eyeglasses

• Refractive error with and without eye drops

• Corneal topography (Orbscan II, Oculus Topography)

• Corneal thickness (Sonogage 50Hz)

• Endothelial cell count (Specular Microscope, Conan)

• Fundus examination

Dünyagöz Difference in CCL Treatment

The first CCL treatment in Turkey has been applied by Dünyagöz Hospitals. The first “Keratoconus Diagnosis and Treatment Center” has been established within Dünyagöz Hospitals. These centers are equipped with all the necessary devices related to the diagnosis and treatment of keratoconus.

Dünyagöz is the most experienced center in the field of CCL in Turkey. Dünyagöz Hospitals have performed the greatest number of CCL treatments until today (over 20,000). Collaborative works with IROC Clinic (Zurich, Switzerland with Prof. Seiler and his team) where CCL was invented and developed are still continuing.

An archive system is very important due to the importance of the follow-up in keratoconus disease. Dünyagöz Hospitals have patient-specific archiving.

INTRACORNEAL RING

Patients who cannot use contact lenses or for whom contact lenses are considered unsuitable may benefit from the intrastromal corneal ring insert procedure, provided that keratoconus is not at an advanced stage. Under local anesthesia, intracorneal rings (INTACS, Keraring, Ferrara) are inserted into the cornea through channels opened within seconds using Femtosecond Laser.

Intracorneal Rings Specifications:

• Transparent,

• Micro-dimensional,

• In varying thickness depending on the diopter to be corrected,

• Implanted in the corneal tissue of the eye,

• In crescent form and composed of 2 parts.

These rings are not noticed from outside and most importantly, their presence is not felt, like contact lenses. The rings can be removed easily at any time and leave no permanent scar which may affect vision since they are not placed in the visual center. Rings with different thicknesses are implanted according to the stage of keratoconus.

When Intacs rings are inserted into the corneal tissue, they flatten the cornea and eliminate the coning of the cornea which is caused by keratoconus. Myopia is also corrected with this procedure.

The ring implanted in the eye is clear and made of a material which is compatible with ocular tissue, without causing any problems in its lifetime, and can also be removed when required. It cannot be seen from the outside after the surgery and its presence in the eye cannot be felt either.

What Types of Rings Are Available? 

Currently, two types of rings are used worldwide:

INTACS (Addition Technology): These are hexagonal rings with a diameter of 7 mm.

KERARING / FERRARA RING (Mediphacos/AJO Company): These rings are in the shape of a triangular prism and have a diameter of 5 mm.

At Dünyagöz Hospitals, corneal ring treatment is used to improve quality of vision in keratoconus. While no publication has yet reported that ring implantation stops disease progression, one-year follow up of the patients who have received a ring implantation at Dünyagöz as of today showed that nearly 88% of the patients had no progression. Therefore, patient follow-up after surgery is essential. If any progression is seen, CCL treatment can be performed after the ring operation.

DRY EYES

This is a tear and ocular surface disease that results in symptoms of discomfort, blurred vision and tear deficiency or imbalance. The tear film layer is of vital importance in supplying and moisturizing the ocular surface and maintaining a clear corneal tissue.  Being most common in autoimmune diseases such as Sjögren’s syndrome, dry eye develops as a result of tear deficiency or excessive evaporation of tears in cases of absence of the lacrimal glands, occluded ducts of the glands, inflammation of the eyelids, contact lens use and vitamin A deficiency.  Many oral drugs, computer use, ambient humidity, habits such as smoking and other external factors are also influential in the development of dry eye. Appropriate treatment for dry eye is given after a detailed eye examination and tests evaluating the quality and amount of tears.

OTHER CORNEAL DISEASES

Corneal Infections 

The most common causes of corneal infections include contact lens use, herpes keratitis caused by the herpes virus and fungal keratitis developing after herbicide injuries.  Eye redness developing during contact lens use may be the first sign of infection. Unless confirmed otherwise by a doctor, the patient should stop wearing lenses. Many bacterial and parasitic infections may lead to corneal ulcers severe enough to result in permanent impairment of vision and even loss of vision in contact lens wearers.

Herpetic keratitis is the most common cause of corneal infections and associated corneal opacities in adults in developed countries. Fungal keratitis is common in herbicide injuries suffered by people living or working in rural areas.

Corneal infections are serious diseases which threaten vision. Early diagnosis and accurate treatment are crucial in preventing permanent loss of vision.

Corneal Opacities

The most common cause is scarring that develops after corneal infections. Spots developing due to material build-up in corneal tissue in congenital corneal dystrophy is another major cause. Corneal opacities mostly occur as a result of consanguineous marriage. Corneal transplantation is the method of treatment in cases of permanent vision loss.

Corneal Edema

Transparency of the cornea is ensured by the endothelial cells in the inner surface of the cornea, which work like a pump. If the number of these cells falls below a certain value, blurred vision and corneal edema occurs. Cataract surgeries are the primary cause. Having a cataract surgery performed by inexperienced doctors and without the required level of surgical quality may lead to corneal edema. Though rarely, permanent corneal edema may develop in children and adults due to congenital insufficiency of endothelial cells. Treatment is only possible with corneal transplantation. Historically, the entire cornea used to be replaced in eyes with this problem. Today, sutureless endothelial corneal transplantation is possible, in which there is less risk and only the diseased tissue is replaced.

Keratitis

Inflammation of the cornea is called “keratitis”. There are several types of causes. Early diagnosis is very important for treatment.

CONJUNCTIVA

Conjunctivitis 

The conjunctiva is a thin, clear membrane lining the inner surfaces of the eyelids and the white part of the eyeball (sclera). Inflammation of this thin, clear membrane is called conjunctivitis. Conjunctivitis makes blood vessels larger and more visible, causing the eyes to look red. It may develop in one eye or both eyes.

What are the Symptoms of Conjunctivitis? 

• Increased watering

• Pain in the eye

• Itching in the eye

• Excessive eye discharge

• Crusting of the eyelashes in the mornings

What Causes Conjunctivitis?

• Infections (viral and bacterial)

• Allergies

• Environmental factors

Treatment of Conjunctivitis

Prescription eye drops can be recommended by the ophthalmologist to help minimize drainage or discomfort. Timely and accurate antibiotic treatment is important for treatment. Bacterial or viral conjunctivitis is highly contagious when there is discharge from the eyes.

Conjunctival Tumors

Their incidence is 1 in 2,500 people. The prevalence of benign tumors is 3 times higher than malignant ones. Corneal and conjunctival tumors are evaluated together since they frequently affect both tissues simultaneously. Many tumors can spread to the eyelids because of their adjacency.

Tumors:

• Cysts: Clear cysts originating from the conjunctival tissue.

• Papilloma: Papillomas are multipartite tumors associated with the human papillomavirus (virus causing warts). They can be pedunculated or sessile.

• Conjunctival intraepithelial neoplasia: Intraepithelial cancer with a cauliflower, white plaque or gelatin-like appearance.

• Corneal carcinoma: White plaque-like raised tumors located in the limbus, the border of the cornea and conjunctiva.

• Melanocytic nevus (mole), melanocytosis and melanomas: These can be light or dark brown with different localizations. Color darkening with age is significant.

• Lymphoid hyperplasia and lymphomas

• Epibulbar dermoid or dermolipoma: White, raised and dome-shaped formations in the junction of the cornea and conjunctiva. They are usually localized in the lower hemisphere.

Treatment typically requires surgical removal. To prevent recurrence after surgery, it may be necessary to administer different drugs in the area from which the tumor is removed during surgery and to use special eye drops after the operation.

CHEMICAL EYE BURNS

Many surface cleaners and chemicals currently used in homes and in industry can cause serious damage to the cornea and ocular surface. Among them, hydrochloric acid, drain openers and alkalis such as quicklime are particularly hazardous. When an injury happens, the eyes should be washed with plenty of clean water and a nearby eye clinic should be consulted. Medication, covering of the ocular surface with a special tissue, stem cell transplantation and, in more severe cases, corneal transplantation can be required.

CORNEAL TRANSPLANTATION

The cornea is the transparent, curved front part of the eye which focuses light, protects the eye against external factors, plays a major role in vision and is the eye’s most important refractive lens. The clarity of the cornea can be compromised by many diseases. Such diseases can be congenital, genetic or microbial. Should keratoconus be at the latest stage with highly reduced vision and the patient cannot benefit either from contact lenses or intrastromal corneal rings, the only treatment option that remains is corneal transplant.

And some diseases like keratoconus can alter the shape of the cornea, requiring corneal transplant.

Corneal Transplantation 

At Dünyagöz Hospitals Group, corneal transplant operations are performed by specialist ophthalmologists in operating rooms which are equipped with a comprehensive set of state-of-the-art devices and instruments required for all ocular surgeries, from the most minor to the most complicated.

Corneal transplantation (Keratoplasty), commonly known by the public as an eye transplant, is in fact a surgical procedure where only the cornea that is distorted due to various diseases is replaced with a donated cornea. In corneal transplant surgery, a circular piece with a diameter of 6-9 mm is excised from the healthy donor cornea; a piece of the same diameter is also extracted from the recipient (patient) cornea and the healthy piece is then sutured into this opening.