The cornea is the curved transparent layer of the eye, which is located at the very front of the eye AND has the task of focusing light, protecting the eye from external factors and plays a major role in the realization of the visual function.
Corneal Examination Methods
Ophthalmologists use a number of devices to assess corneal morphology and function;
- Biomicroscopy: It is used to examine the cornea and other structures of the anterior segment. Light beams of different thicknesses are sent from different angles to magnify the biomicroscopy and the cornea is examined. It is the most commonly used examination method.
- Keratometry: Measures the refractive power of the cornea. It is used before contact lens and intraocular lens implantation.
- Topography: It is used to analyze the anterior surface of the cornea topographically.
- Esthesiometry: It is used to evaluate corneal sensitivity.
- Examination of the cornea by staining: Defects on the corneal surface can be visualized with "fluorescein and rose bengal" solution.
- Pachymetry: Corneal thickness measurement.
- Specular microscopy: Shows endothelial cell number and structure.
Keratoconus
Keratoconus is a disease caused by the thinning and sharpening of the cornea, the transparent layer of the eye, with progressive astigmatism and myopia. Patients are usually only aware of their disease in their 20s, which usually begins in adolescence. The disease progresses between the ages of 20 and 40 and enters a stable period after the 40s. The cornea is a very important part of the eye. Light enters the eye through the cornea. The cornea refracts or focuses the rays, allowing you to see clearly. As the cornea deteriorates in keratoconus, vision also deteriorates. The presence of keratoconus can make some activities such as driving a car, typing on a computer, watching television or reading difficult.
What are the Causes of Keratoconus?
- Ultraviolet rays,
- Eye rubbing
- Environmental factors,
- Use of rigid contact lenses,
- Genetic (familial) predisposition,
- Chronic eye irritation
- Although the cause of Keratoconus disease is not known exactly, genetic and mechanical traumas play the most important role in its development.
What are the Symptoms of the Disease?
Persistent allergy or itching in the eye,
Progressive myopia and astigmatism,
Not being able to see clearly despite glasses,
Increased sensitivity to light,
Glare
Straight lines appear bent or wavy
The contact lens worn because the cornea protrudes does not fit the eye or causes discomfort
These symptoms indicate a high risk of keratoconus disease. In such cases, it is useful to be examined by a specialist physician. Because early diagnosis and treatment of keratoconus disease is of great importance in preventing serious vision problems that may occur in the future.
Keratoconus Treatment Methods
Topolazer:
With topolaser, a topographic map of the cornea is created in 3D like a fingerprint and laser treatment is programmed specifically for each patient.
Unlike full Wavefront treatment, this treatment is based on the principle of evaluating only the upper surface irregularity of the cornea.
Who is Topolaser Applied to?
- Patients who cannot wear contact lenses,
- After 6 months, patients received cross-linking treatment to improve vision,
- Patients whose corneal thickness will remain at least 400 microns after laser application,
- It can be applied to keratoconus patients who have previously undergone corneal transplantation and have low vision due to high astigmatism.
Corneal Cross Linking (CCL)
Keratoconus is a disease caused by deformity of the transparent layer (cornea), which forms the front part of the eye, as a result of increased curvature and thinning. CCL is one of the treatment methods for keratoconus. The aim of Corneal Cross Linking (CCL) treatment is to strengthen the corneal structure and stop the disease.
What is CCL (CORNEAL CROSS-LINKING) Treatment Process?
Riboflavin (B2 vit) Instillation
The eye is numbed with a topical anesthetic drop before the procedure. After topical anesthetic drops, the corneal epithelium is mechanically lifted with a blunt spatula. Riboflavin solution is instilled on the cornea for 30 minutes, 2 drops at 5 minute intervals for 30 minutes.
How is UV Light Applied?
After 30 minutes, the patient is placed in the biomicroscope. After riboflavin fluorescence is seen in the anterior chamber, the patient is taken back to the operating room. 370 nm UV is applied at a distance of 4-5 cm from the corneal surface in an area of approximately 7 mm for 5-10 minutes. During UV application, 2 drops of Riboflavin are instilled every 1 minute. After the procedure, a bandage contact lens is placed on the eye and the eye is not closed.
UV Cross-Linking (cross-linking at the molecular level) Treatment
UV-Cross Linking surgery can stop the progression of keratoconus disease by using UVA light and Riboflavin to act on the cornea's collagen molecules and improve corneal mechanics.
Results of Applied CCL Operations
Dünyagöz Hospitals' first scientific study on this subject was presented at the European Cataract and Refractive Surgery Congress (ESCRS, September 8-12, 2007) in Stockholm and was accepted for presentation at the American Academy of Ophthalmology (AAO) Congress.
Which examinations and tests are performed before surgery?
- Visual acuity with and without glasses
- Refractive error with and without drops
- Corneal topography (Orbscan II, Oculus Topography)
- Corneal thickness (Sonogage 50Hz)
- Endothelial count (Specular Microscope, Conan)
- Fundus examination
İntracorneal Ring
If keratoconus is not in the advanced stage in patients who cannot wear contact lenses or whose eyes do not fit contact lenses, intracorneal ring application may be a good alternative.
It can be treated by placing intracorneal rings (INTACS, Keraring, Ferrara) into the channels opened in seconds with Femtosecond Laser under local anesthesia into the cornea.
What are the Features of the Corneal Inner Ring?
- Transparent,
- Micro size,
- Varying in thickness according to the amount of diopters to be corrected,
- Placed in the cornea of the eye,
- They are special apparatus in the shape of a half-moon and consisting of 2 parts.
These rings are not noticeable from the outside and most importantly, they do not feel like contact lenses. The rings, which can be removed when deemed appropriate by the physician, do not leave any permanent scar that will affect vision as they are not placed in the visual center. The rings, which have different thickness types, are placed by the physician according to the degree of keratoconus disease.
When Intacs is placed into the corneal tissue, it eliminates the sharpness and curvature of the cornea caused by keratoconus disease by stretching it like a pulley. In the meantime, the person's myopia also improves.
The ring placed inside the eye is transparent and compatible with your eye tissue, it is a material that will remain for a lifetime without causing any problems and can also be removed when desired. After the surgery, it is invisible from the outside and its presence in the eye is not felt.
What are the Ring Types?
There are two types of rings currently in use in the world:
INTACS (Addition Technology): 7 mm diameter hexagonal rings.
KERARING / FERRARA RING (Mediphacos/AJO Company): 5 mm diameter rings with a triangular prism structure.
Cornea Transplant
The cornea is the curved transparent layer of the eye, located at the front of the eye, which has the task of focusing light and protecting the eye from external factors, plays a major role in visual function and is the most important refractive lens of the eye. The transparency of the cornea can be impaired by many diseases. These diseases can be congenital, genetic or microbial. In the last stage of keratoconus, if vision is severely impaired and the patient cannot benefit from contact lenses or corneal rings, corneal transplantation is the treatment option.
Some diseases, such as keratoconus, may require corneal transplantation by changing the shape of the cornea.
About Cornea Transplant
Corneal transplantation is the replacement of diseased tissue with healthy donor tissue in diseases where the shape or transparency of the cornea is impaired. It is medically known as keratoplasty. The most common diseases are keratoconus, corneal edema, microbial ulcers of the cornea or spots (opacities) that develop as a result of accidents, injuries and hereditary corneal spots. In the past, all corneal transplants, regardless of the cause of the disease, involved a full-thickness replacement of corneal tissue (penetrating keratoplasty). This procedure had complications such as severe infection, rejection of the transplant tissue and inability to see due to irregular astigmatism.
Today, corneal transplants are performed for whichever layer of the cornea is affected by the disease. Transplantation techniques vary according to the condition of the endothelial cell, which is located in the innermost layer of the corneal tissue and keeps the cornea transparent. Corneal transplants in which the anterior layer of the cornea is replaced are called anterior lamellar keratoplasty (DALK) and corneal transplants in which the endothelium is replaced (DSAEK, DMEK). In developed countries such as the USA, more than 50% of corneal transplants are performed with these new methods.
At Dünyagöz, advanced corneal transplants such as DALK, DSAEK or DMEK are routinely performed depending on the patient's corneal disease. In this way, patients from our country and different countries of the world regain light and vision thanks to these new corneal transplantation techniques. Classical full-thickness corneal transplants are now performed in very few patients and only in mandatory cases.
In keratoconus and corneal stains where the endothelium is intact, the front 85-90% of the cornea is replaced in anterior lamellar keratoplasties called DALK. In such corneal transplants, the possibility of rejection of the donor tissue is greatly reduced or almost eliminated. The life expectancy (lifespan) of the tissue becomes equal to that of the patient's healthy eye.
In eyes with corneal edema or rejection of previous corneal transplantation and inadequate endothelium, endothelial cell transplantation is performed through a small incision called DSAEK or DMEK. In such corneal transplants, patients can return to their normal lives in a few weeks. Patients do not wait for a year for wound healing and suture removal as in conventional transplants. In these eyes, the eye number does not change and astigmatism does not occur after corneal transplantation.
Patient and donor corneas can be cut in planned shapes with Femtosecond laser instead of the blades called trepan. In femtosecond laser cut cornea transplants, less astigmatism occurs and patients can see better.