The cornea is the clear covering of the front of the eye which bends, or refracts, light rays as they enter the eye. For clear vision to occur, the cornea must have the correct shape and clarity to focus incoming light rays precisely on the retina at the back of the eye. When the cornea becomes cloudy or misshapen from injury, infection or disease, transplantation may be recommended to replace it.
There are several different corneal transplant procedures available to help restore vision in patients with corneal problems. The traditional corneal transplant procedure involves replacing the entire damaged cornea with a healthy one from a human donor, which is obtained from an eye bank. However, technological advances have allowed for the development of specialized procedures that replace only the damaged part of the cornea, while leaving the healthy parts intact.
There are diseases that only affect the innermost layer of the cornea, called the endothelium. The endothelial cells function like a pump and keep the cornea from swelling. Fuchs' Dystrophy, an inherited eye disease that causes the endothelial cells to degenerate, results in corneal swelling and poor vision. As this condition progresses, vision will continue to worsen as damaged cells cannot grow back.
In the past, a patient with a disease that only affected their endothelium needed to have their entire cornea replaced with a donor cornea (penetrating keratoplasty). This required ~ 16 sutures, a long visual rehabilitation, and other risks including rejection and wound dehiscence. Now there are advanced surgical techniques where partial thickness cornea transplants can be performed, and only the diseased part of the cornea is replaced. These newer techniques are safer and provide a faster, better visual recovery than traditional penetrating keratoplasty.
Endothelial keratoplasty (EK) is the generic term for partial thickness cornea transplants that replace the innermost layers of the cornea. Descemet stripping automated endothelial keratoplasty (DSAEK) was the first widely utilized endothelial keratoplasty techinque. Descemet membrane endothelial keratoplasty (DMEK) is the latest iteration of EK and provides, in general, a faster, better visual recovery with less risk of rejection than DSAEK.
Short for Descemet membrane endothelial keratoplasty, DMEK is a partial thickness cornea transplant where the innermost layers of the cornea (Descemet membrane, endothelium) are replaced with donor Descemet membrane and endothelium. This provides an exact anatomic replacement.
The surgery takes roughly 45 minutes and is typically done without the need for general anesthesia. A gas bubble is placed in the eye at the end of the case to help the transplant stay in place, and the patient is then allowed to go home. It is important that patients lie flat for 24 hours to maximize contact of the air bubble with the graft. For the next 48 hours, patients will lay flat 50% of the time (alternating 2 hours up, 2 hours down). Steroid and antibiotic drops will be used as the eye heals. Vision will be blurry initially but typically starts clearing up around day 3-4 (when the gas bubble clears the pupil) and it will improve over the next several weeks.
Short for Descemet stripping automated endothelial keratoplasty (DSAEK), DSAEK is also a partial thickness cornea transplant where diseased Descemet membrane and endothelium are replaced with donor Descemet membrane, endothelium, and posterior stroma (middle layer of the eye).
DSAEK surgery also takes roughly 45 minutes. The type of anesthesia utilized will be discussed with each patient individually. A gas bubble is placed in the eye at the end of the case to help the transplant stay in place, and the patient is then allowed to go home. It is important that patients lie flat for 24 hours to maximize contact of the air bubble with the graft. Steroid and antibiotic drops will be used as the eye heals.
RISKS OF EK SURGERY
While the EK (DMEK, DSAEK) procedures are considered safe for most patients, there are certain risks involved with any type of surgical procedure including infection, bleeding and more. Although rare, there is a risk of transplant rejection, which may result in redness, sensitivity to light and blurred vision. If you are experiencing these or any other symptoms after DMEK or DSAEK, you should contact your doctor to prevent any damage from occurring.
To learn more about the DMEK or DSAEK corneal transplant procedure, and to find out whether or not one of these procedures is right for you, please call us today to schedule a consultation.
Glaucoma is the leading cause of blindness and visual impairment in the U.S., and can affect patients of all ages, many of who do not experience any symptoms and may not be aware that they have the disease. Glaucoma actually refers to a group of diseases that cause damage to the optic nerve as a result of increased pressure within the eye, but can also be caused by a severe eye infection, injury, blocked blood vessels or inflammatory conditions of the eye.
There are two main types of glaucoma, open-angle and angle-closure. Open-angle glaucoma is the most common type of glaucoma and involves fluid in the eye not draining properly through the trabecular meshwork. Angle-closure glaucoma involves a sudden buildup of pressure in the eye and poor drainage because the angle between the iris and the cornea is too narrow.
While some patients may experience symptoms from glaucoma as the disease progresses, others do not learn they have the condition until they undergo a routine eye exam. Tonometry (checking the eye pressure), fundus exams, and visual field testing are all used to diagnose glaucoma.
Treatment for Glaucoma
Once glaucoma has been diagnosed, treatment should begin as soon as possible to help minimize the risk of permanent vision loss. There is no cure for glaucoma, so treatment focuses on relieving symptoms and preventing further damage from occurring. Most cases of glaucoma can be treated with eye drops, laser or microsurgery. The best treatment for your individual case depends on the type and severity of the disease, and can be discussed with your doctor.
- Eye drops are used to reduce fluid production in the front of the eye or to help drain excess fluid, but can lead to redness, stinging, irritation or blurry vision. Patients should tell their doctor about any allergies they have to minimize the risk of side effects.
- Laser surgery for glaucoma aims to increase the outflow of fluid from the eye or eliminate fluid blockages through laser trabeculoplasty, iridotomy or cyclophotocoagulation.
- Microsurgery involves a surgical procedure called a trabeculectomy, which creates a new channel to drain fluid from the eye and reduce the pressure that causes glaucoma. Surgery is often performed after medication and laser procedures have failed.