Corneal Diseases
The cornea is the transparent, dome-shaped tissue located in front of the iris and pupil, the outermost layer of the eye. It protects the eye's internal structures and provides the primary refraction of incoming light, contributing to the healthy projection of images onto the retina. It is the most refractive layer in our eye. Therefore, even the slightest defect in the cornea can significantly impact vision.
Frequently asked questions?
What is the Structure of the Cornea?
A healthy cornea has a horizontal diameter of approximately 12 millimeters. Viewed from the front, its vertical diameter is 11 millimeters. Its average thickness is 550 microns. Its components are as follows:
Corneal Epithelium: The outermost layer. It's approximately 50 microns thick and consists of five layers of cells. Epithelial cells are produced in the surface tear film. These cells continually migrate upward, replacing older cells. This transformation occurs continuously over an average of one week.
Bowman's Layer: Formed by the compression of collagen fibers. It is the transitional layer between the epithelial and stromal layers. It has a very thin structure.
Corneal Stroma: This middle layer makes up the majority of the corneal thickness. It is composed of collagen fibers. Damage typically results in loss of transparency and curvature, leading to severe vision loss.
Corneal Epithelium: The outermost layer. It's approximately 50 microns thick and consists of five layers of cells. Epithelial cells are produced in the surface tear film. These cells continually migrate upward, replacing older cells. This transformation occurs continuously over an average of one week.
Bowman's Layer: Formed by the compression of collagen fibers. It is the transitional layer between the epithelial and stromal layers. It has a very thin structure.
Corneal Stroma: This middle layer makes up the majority of the corneal thickness. It is composed of collagen fibers. Damage typically results in loss of transparency and curvature, leading to severe vision loss.
How Are Corneal Diseases Diagnosed?
Corneal diseases are diagnosed through various tests performed by ophthalmologists in addition to a general eye examination. Each test evaluates different segments of this layer's structure. These various tests can reveal existing diseases in the cornea. As with all eye-related diseases, early diagnosis is crucial for successful treatment.
Some of the tests used to evaluate corneal morphology and function are as follows:
Biomicroscopy: This device allows binocular examination of the cornea and structures in the anterior segment of the eye. Light beams of varying thicknesses are sent from various angles, and the biomicroscope magnifies the eye's surface tissues to allow examination of the cornea.
Keratometry: This measurement is used to measure the diameter of the curvature of the anterior surface of the cornea and its refractive power as it transmits light from the outside to the inner regions. It is also used in selecting appropriate contact lenses, intraocular lens options, and diagnosing keratoconus.
Topography: This is used to map the anterior surface of the cornea. This allows for the analysis of surface refraction. It is frequently used to determine the suitability of a patient for phakic intraocular lens implants, which are used to treat high degrees of myopia and hyperopia.
Pachymetry: This measurement is used to measure corneal thickness. It is also used to determine whether a patient is suitable for laser surgery, which involves removing a flap from the front surface of the eye.
Specular Microscopy: Used to determine the number of endothelium.
Aesthesiometer: Used to measure corneal sensitivity.
Examination of the cornea by staining: It is used to detect defects on the surface with the help of “fluorescein and rose bengal” solution.
Some of the tests used to evaluate corneal morphology and function are as follows:
Biomicroscopy: This device allows binocular examination of the cornea and structures in the anterior segment of the eye. Light beams of varying thicknesses are sent from various angles, and the biomicroscope magnifies the eye's surface tissues to allow examination of the cornea.
Keratometry: This measurement is used to measure the diameter of the curvature of the anterior surface of the cornea and its refractive power as it transmits light from the outside to the inner regions. It is also used in selecting appropriate contact lenses, intraocular lens options, and diagnosing keratoconus.
Topography: This is used to map the anterior surface of the cornea. This allows for the analysis of surface refraction. It is frequently used to determine the suitability of a patient for phakic intraocular lens implants, which are used to treat high degrees of myopia and hyperopia.
Pachymetry: This measurement is used to measure corneal thickness. It is also used to determine whether a patient is suitable for laser surgery, which involves removing a flap from the front surface of the eye.
Specular Microscopy: Used to determine the number of endothelium.
Aesthesiometer: Used to measure corneal sensitivity.
Examination of the cornea by staining: It is used to detect defects on the surface with the help of “fluorescein and rose bengal” solution.
Corneal Diseases and How Are They Treated?
Corneal treatment varies depending on the type and level of diseases that begin or exist in this area.