Corneal Edema

Cornea is a clear, transparent, dome-shaped structure that covers the front portion of the eyes. An adult cornea is about 0.5 millimeters thick. It comprises five major layers, namely, the epithelium (outer portion, having the ability to regenerate), Bowman's membrane (hard, protective layer), stroma (thickest layer with collagen fibrils), Descemet's membrane (thin layer), and endothelium (one-celled thick innermost layer). Since there are numerous nerve endings in the cornea, it is extremely sensitive. On the contrary, cornea is devoid of blood vessels, hence it appears transparent.

Corneal Edema: What is it?

Cornea functions as a powerful refracting medium, contributing to maximum focusing power of the eyes. Cornea is kept transparent for maximum vision clarity by supplying oxygen from the tears and pumping of water from the endothelium layer. When there is excess hydration or accumulation of fluid in the cornea portion, then it causes corneal swelling; a common eye problem referred to as corneal edema.

Corneal Edema: Causes and Symptoms

This corneal condition is caused by problems related to dehydration, viral infections, endothelial disorder, ocular surgery, traumatic injury, increased ocular pressure, and at times, toxins. Among these, endothelial Fuch's dystrophy is the most common cause of this edema. It is a hereditary disorder, characterized by slow and gradual loss of endothelial cells. Women are at a higher risk of endothelial dystrophy than men.

An infection by herpes virus may result in inflammatory responses in the cornea, leading to edema. Corneal edema may also occur immediately or few years after participating in any kind of ocular surgery. It may occur due to impairment of endothelial layer by ultrasound radiation, damage of Descemet's membrane, and/or infusion of toxic medications in the cornea. In addition, strong topical and systemic medications can lead to edema condition of the cornea.

The most notable early symptoms of corneal edema are distorted or blurred vision, halos around light, eye discomfort, photophobia (increased sensitivity to light), and sensitivity to foreign particles. Symptoms may progress to severe pain in the eyes due to the corneal nerve damage. Pseudophakic bullous keratopathy (PBK) that results in the formation of fluid-filled bullae or blisters is commonly observed after the cataract surgery.

Corneal Edema: Diagnosis and Treatment

As early symptoms of corneal edema are similar to cataracts, it is necessary to undergo ocular evaluation for correct diagnosis of this eye problem. The eye care specialist may conduct specular microscopy, ultrasound, and optical pachymetry (measurement of corneal thickness) in order to confirm the condition.

The treatment strategy varies based on the exact cause of the condition. In case of corneal inflammation caused by ill-fitting or persistent wearing of contact lenses, the use of correct contact lenses is recommended. Similarly, edema caused by increased eye pressure is treated by lowering the pressure. If the swelling is developed as a post-surgery complication, it can be improved by administering eye-drops prescribed by the eye care practitioner. The doctor may recommend antibiotics and anti-inflammatory drops for infection related corneal edema.

In case, corneal swelling is restricted to the epithelial layer, it can be treated by using common salt solution. Over here, salt solution extracts the excess fluid that gets accumulated in the cornea by means of osmosis. In severe cases, corneal transplant may be recommended as a treatment procedure. Proper eye care and eye exercise should be practiced to relieve the symptoms of corneal swelling.

If corneal edema is left untreated for a prolonged duration, then the symptoms may worsen to chronic eye conditions such as stromal edema and intercellular epithelial edema. Hence, in order to avoid such complications, it is always recommended to seek advice from a qualified eye specialist for early diagnosis and correct treatment of this eye problem.