What is a Corneal Ulcer?
Anatomically, the cornea is the transparent film that covers the iris, the pupil, and the anterior chamber. This structure, together with the lens and the anterior chamber, are responsible in refracting light. The cornea consists of unmyelinated nerve endings that are sensitive to various stimuli such as touch, changes in temperature, and chemicals. The reason why it is transparent is because it has no blood vessels; it receives nutrition though from the nutrients from the tear fluid in the outside and the aqueous humor through the inside surface as well as from the neurotrophins coming from the nerve fibers that innervate the cornea.
The cornea has the following layers:
- Corneal epithelium – the outermost part
- Bowman’s layer – this is a tough layer that serves to protect the corneal stroma
- Corneal stroma – this is also known as substantia propria, which is a thick and transparent middle layer that contains collagen fibers and widely distributed keratocytes. Keratocytes are important cells for general repair and maintenance.
- Descemet’s membrane – this layer is otherwise known as posterior limiting membrane. This layer is composed mainly of type IV collagen fibers and is a thin acellular layer that serves as the basement membrane.
- Corneal endothelium – this layer is composed of simple squamous or low cuboidal monolayer and are responsible for regulating the fluid level and the exchange of solutes between the aqueous and corneal stromal compartments.
Corneal ulcers then occur when the outer corneal surface develops a sore or an opening usually brought about by an infection.
Corneal Ulcer Symptoms
The typical symptoms of a corneal ulcer include the following:
- Pain sensation that increases upon exposure to bright lights
- Watery eyes
- Pus formation and draining
- Blurred vision and the sensation that something is in the eye
- Swollen eyelids
- Formation of white patch on the cornea, which is very visible in large corneal ulcers
Causes of Corneal Ulcer
The common cause of corneal ulcer is an infection.
- Bacterial infection as a cause of corneal ulcer is common in individuals who wear contact lenses.
- Both the herpes simplex virus and the varicella virus may also cause corneal ulcers.
- Overuse of eye drops containing steroids may promote the development of fungal infection.
- Injury to the cornea or minor tears can damage the outer corneal surfaces. Once damaged, it will allow entry of bacteria and other organisms and cause the infection.
- Diseases that may lead to dry eyes can also lead to ulcers. Without the normal production of tears or water in the eyes, there would not be enough germ-fighting protection that tears can provide.
- In Bell’s palsy, it damages the facial nerve or the cranial nerve 7, which is responsible for the closure of the eyelids. Since the facial nerve is affected, there wouldn’t be enough innervations to the muscles that close the eyes. If the eyelids are open, the cornea is subject to the cold air in the environment that easily dries the eye. This situation would lead to the vulnerability of the cornea to develop ulcers.
- Chemicals and harmful solutions splashes to the eyes can damage the cornea.
- People who wear contact lenses are at risk for infection. There are contact lenses that can be worn for several days without removing them at night; this type of contact lenses put people at higher risk for damaging the cornea. Instances that contact lenses can cause damage to the cornea are as follows:
- The edges of the contact lens have the tendency to scrape the corneal surface and start the ulcerations, facilitating the entry of bacteria.
- Since there are contact lenses that can be worn for extended periods, dirt particles can be trapped beneath the lenses and can rub the cornea.
- Wearing contact lenses for an extended period can cause blockage of the normal flow of oxygen to the corneal surfaces. Once this happens, it subjects the eye more vulnerable to injury and infections.
Corneal Ulcer Treatment
The following are the various treatment methods given to patients who have corneal ulcers:
- Foremost, if the corneal ulcer is caused by the contact lenses word for an extended period, then the ophthalmologist would usually remove the contact lens.
- If the ophthalmologist suspects that the ulcer is caused by bacterial infection, he or she would not recommend putting a patch on the eye as patching will create a dark environment that promotes growth of bacteria.
- In severe cases, the patient may need to be hospitalized.
- If the cause of the ulceration is due to bacterial infection, antibiotic eye drops will be prescribed by the physician to control the infection. The frequency of using an eye drop would also depend on the severity and the size of the ulcer.
- Pain medications can also be prescribed to control the pain sensation.
- In most severe cases wherein the ulcers do not respond to any medication and pose more serious complications, the next choice of treatment is corneal transplant.
Self-care techniques can also be done at home and include the following:
- If one feels and sees signs and symptoms of corneal irritation and one is wearing a contact lens, it is recommended to remove the contact lens right away.
- Application of cool compresses to the affected eye.
- Never touch or rub the eyes with the use of your finger to avoid irritation. Also, some bacteria present in the hands can easily enter the ulcerations.
- To limit the spread of infection, always make sure that your hands are washed and dried properly.
- Over-the-counter pain medications such as acetaminophen and ibuprofen can be taken.
To prevent the occurrence of corneal ulcers, the following points can be considered:
- Before handling contact lenses, make sure that the hands are properly washed and cleaned.
- Remove contact lenses at night before going to bed and carefully clean them.
- Never sleep with the contact lenses in the eyes.
- Disinfectant solutions are used to store contact lenses when not in use during the night.
- Remove the lens every time you feel that you eyes are irritated.
Corneal Ulcer Pictures
Photo collection of Corneal Ulcer…