The cornea is the visible clear portion of the front of the eye. It focuses 70% of the light that enters the human eye. Visual clarity comes from the perfect arrangement of collagen fibrils in the middle layer of the cornea called the stroma along with the perfect balance of hydration. The inner most layer of the cornea (endothelium) controls the hydration. The cornea is protected by the tightly arranged outside layer of epithelial cells. These layers work together to keep the cornea clear, allowing light to focus. When all the layers function properly, the cornea is designed to last more than a lifetime.
When any of these layers do not function properly, the focusing ability of the cornea will decrease. Fortunately, advances in corneal treatments restore hope for those with corneal disorders. The most recent treatments address the problematic layer of the cornea and leave the other layers undisturbed. The following description highlights some of the recent advances.
Keratoconus is the condition where the thick stroma layer of the cornea progressively becomes thinner and weaker. It results in the cornea being shaped like a cone as opposed to a curve. This bends the light in wrong directions destroying the focusing power of the cornea. It’s caused by a combination of genetic and environmental factors including eye rubbing.
The progression of keratoconus can be halted with corneal crosslinking. This technique relies on riboflavin drops to react with UV light in the cornea to strengthen bonds among the collagen fibrils resulting in increased corneal strength. Corneal crosslinking has a successful track record. This technique is best used as early as possible in the diagnosis. In advanced cases of keratoconus, sometimes the best option is corneal transplant using the technique known as DALK (Deep Anterior Lamellar Keratoplasty). DALK replaces the epithelium and stroma only and leaves the normal endothelium intact. Preserving the endothelium reduces the rate of rejection.
This condition, named over 100 years ago after the Austrian ophthalmologist Ernst Fuchs, is a genetic condition where the endothelial cells are pushed out of the way by bumps that develop on the Descemet’s membrane. The microscopic bumps don’t allow the endothelial cells to dehydrate the cornea so it becomes swollen. A swollen cornea becomes grey in color and doesn’t focus light properly.
Fortunately, there is an excellent cure for Fuch’s Dsytrophy. The inside layer of the cornea can be removed and replaced. This technique called DMEK (Decemet’s Membrane Endothelial Keratoplasty) has a high success rate with excellent visual outcomes and a very low rejection rate. This surgery replaces the inside layer of the cornea (about 1/100th of a millimeter thick) and leaves the rest of the normal cornea untouched. This restores the normal balance of corneal hydration and results in a clear cornea.
Trauma, infections and a host of other genetic disorders can affect the clarity of the cornea. Each case is unique. Schedule your consultation with Dr. Aaron Waite, who is well versed in all available corneal treatments, and find the best corneal treatment options for you.