Endothelial cells are specialized cells that form a single layer lining the interior surfaces of various bodily structures, including blood vessels, lymphatic vessels, and the back surface of the cornea in the eye. They create a barrier between circulating fluids and surrounding tissues, regulating the passage of substances to maintain tissue health.
The Significance of Endothelial Cell Count
Measuring the endothelial cell count holds particular significance for eye health, especially concerning the corneal endothelium. This layer of cells maintains corneal clarity by actively pumping excess fluid out, preventing swelling and preserving clear vision.
A healthy endothelial cell count is necessary for good vision and successful eye surgeries, such as cataract surgery and corneal transplants. Reduced cell count diminishes the cornea’s ability to pump fluid, leading to corneal swelling (edema). This swelling can cause symptoms like glare, halos, and reduced visual clarity, potentially impairing vision. Monitoring the count helps eye care professionals assess condition progression and make informed decisions, especially before surgery.
How Endothelial Cell Count is Measured
Specular microscopy is the primary non-invasive technique for measuring endothelial cell count. This method involves taking a photograph of the endothelial cell layer. The captured high-resolution images allow for detailed analysis.
The analysis includes determining cell density (cells per square millimeter) and assessing morphology (cell shape and size). Healthy endothelial cells typically appear uniform and hexagonal. The procedure is quick, painless, and non-contact, providing important information about corneal health.
What Affects Endothelial Cell Count
Several factors can lead to changes, typically a decrease, in the endothelial cell count. A natural decline in cell count occurs with aging, with an average rate of approximately 0.6% per year after 18 years of age. The normal adult corneal endothelial cell density is typically between 2500 and 3000 cells/mm², though this can vary.
Specific eye conditions can also impact the count. Fuchs’ endothelial dystrophy, a progressive genetic disorder, causes gradual cell loss, leading to fluid buildup and corneal thickening. The annual loss rate in Fuchs’ dystrophy can be significantly higher than normal age-related decline, ranging from 7.7% to 8.4% depending on disease stage. Certain types of glaucoma and uveitis can also lead to cell decline and changes in cell morphology.
Prolonged or improper contact lens wear can stress corneal cells, potentially affecting health. Eye trauma can damage the corneal endothelium. Ocular surgeries, including cataract surgery or corneal transplantation, can also result in cell loss due to surgical manipulation and energy used. A decrease in cell density often occurs during the first year after cataract surgery, with age and preoperative cell density predicting cell loss.
A reduced or unhealthy endothelial cell count can lead to corneal swelling (edema) and vision impairment. When the cell count drops below a certain level, often around 1,000 cells per square millimeter, the cornea may begin to swell. This condition may necessitate medical interventions, such as hypertonic saline drops, or surgical interventions like corneal transplantation.