What are Corneal Ulcers?

To tell in simple words, Ulcers which form in the eye ae known as Corneal Ulcers. THats it! Well, let us be elaborate. Any inflammaion, swelling which becomes a disruption in the normal tissues and texture of the eye is an ulcer, which is also known as Eyesore - a version similar to bedsore; but in the eye - or in more scientific words - Ulcerative keratitis. In an eyesore, there is infection of the cornea portion of the eye - i.e. the transparent central part of the eye with disruption of the stroma layer. This happens mostly in the Tropical countries where there is lot of heat, also in the agrarian societies and by large in developing and under developed countries where Vitamin A deficiency is present at large.

Classification of Corneal Ulcer
ICD-10 - H16.0
ICD-9 - 370.00
MedlinePlus - 001032 001017
eMedicine - oph/249

Contents of this article

1. Superficial and deep corneal ulcers
2. Difference in the Ulcers formed by various classes of Micro-organisms
1. Bacterial Keratitis
2. Fungal Keratitis
3. Viral Keratitis
4. Acanthamoeba Keratitis
5. Chlamydia Trachomatis
3. Location of the ulcer
1. Central ulcers
2. Peripheral Ulcers
3. Border ulcers including special type of ulcer known as the Mooren's ulcer
4. Symptoms of Corneal ulcers
5. Diagnosis of corneal ulcer
6. What are Refractory corneal ulcers?
7. What are Melting ulcers?
8. How does an ulcer in the eye get better?
9. References for this article on Corneal Ulcer

 Superficial and deep corneal ulcers

Thus we have come to know that there are basically two types of ulcers. Superficial ulcers and deep ulcers. Ulcers in the eye are a common trouble or a disease. Ulcers are commonly cause by trauma, many a times by touch of vegetable matter, chemical injury, also because of contact lenses, infections b y micro-organisms like bacteria, virus, protozoa, Chlamydia and the fungus, entropion, distichiae, corneal dystrophy, and keratoconjunctivitis sicca (dry eye).

Difference in the Ulcers formed by various classes of Micro-organisms
1. Bacterial Keratitis
2. Fungal Keratitis
3. Viral Keratitis
4. Acanthamoeba Keratitis
5. Chlamydia Trachomatis

1. Bacterial Keratitis -
It is caused by initiation of infection by bacteriae like Staphylococcus aureus, Streptococcus viridans, Escherichia coli, Enterococci, Pseudomonas, Nocardia and many other bacteria. Infection is most of the times superficial and treatment immediately resolves the infection.

2. Fungal Keratitis -
It is caused by initiation of infection by fungus like Aspergillus sp., Fusarium sp., Candida sp., as also Rhizopus, Mucor, and other fungi. The ulcers caused by Fungi are deep, bad and severe types of ulcers in the cornea. They appear very slowly and progress gradually. The person does not suffer from any major trouble by the slow progress but the vision can become hazy, along with reddening of the eyes is prominent with one or multiple spots of ulcer in early stage or a full grown ulcer in later stages is visualised. If not treated properly, the cornea can get completely damaged, blindness occurs permanently and the fungal infection can spread deeper through the optic nerve tract.

3. Viral Keratitis -
It is caused by initiation of infection by viral activities seen prominently as corneal ulceration and is caused by virus like Herpes simplex, Herpes Zoster, Adenoviruses, coronaviruses & many other viruses. Of these the bad ones are the ulcers caused by Herpes Zoster virus which cause dendritic ulcers and these can recur or relapse over the comeplete life time of the person if not treated vigorously and properly.

4. Acanthamoeba Keratitis -
It is caused by Protozoal infection which can be seen in swimmers with contact lens usage and this infection causes severe pain in the eye.

5. Chlamydia Trachomatis -
It is a bacterial species from the genus Chlamydia. It can also contribute to the development of corneal ulcers.

 So What actually happens to the eye in these corneal ulcers?

As we have said above, the corneal ulcers are basically of two types. Superficial Ulcers and Deep ulcers.
Superficial ulcers involve the loss of upper part of the eye - that is the epithelium. Deep ulcers extend into the stroma of the eye ball and thus can result into scarring of the cornea with permanent marking on the cornea with partial blindness and perforations in the cornea, which is very dangerous if not treated in time.

Location of the ulcer

The ulcer in the cornea can be located at 3 areas.
1. Central ulcers
2. Peripheral Ulcers
3. Border ulcers including special type of ulcer known as the Mooren's ulcer

Central Ulcers -

Caused by trauma, dry eye, or exposure from facial nerve paralysis or exophthalmos.

Peripheral Ulcers -

Caused by Entropion, severe dry eye and trichiasis (inturning of eyelashes).

Border ulcers -

Caused by Immune-mediated eye disease at the border of cornea and sclera.

Moorens Ulcer

Caused by systemic diseases like Rheumatoid arthritis, rosacea, systemic sclerosis which cause sclerosis of the cornea which have a appearance of circumferencial crater like depression just inside the limbus with an overhanging edge

 Symptoms of Corneal ulcers

Although signs are of more importance than to symptoms, still the symptoms should not be neglected. THe symptoms of corneal ulcers are as follows -

1. Extreme painful condition probably because of nerve exposure
2. Tearing of the cornea of eye
3. Squinting
4. Vision loss of the eye
5. Anterior uveitis, such as miosis (small pupil), aqueous flare (protein in the aqueous humour)
6. Redness of the eye

 Diagnosis of corneal ulcer

Diagnosis of the corneal ulcer can be best made using a slit lamp under magnified viewing with fluorescent staining. In this mannerthe ulcerated corneal stroma appears green in the slit lamp examination and thus margins of the corneal ulcer can be examined and even the dendritic ulcers can be observed for their pattern of staining.

The Descement membrane bulges forward after staining and appears as a dark circle with a green boundary.

The Rose Bengal dye can also be used for Supra vital staining purposes but it is not adviced unless necessary because it causes irritation to the eye.

This staining helps to identify parts of the cornea which can be scrapped and examined under the microscope thus to reveal the micro-organism responsible for the trouble.

Keratoconjunctivitis sicca is examined by the Schirmer's test and further diagnosis should also be made of the facial nerve to rule out facial nerve paralysis.

 What are Refractory corneal ulcers?

Refractory corneal ulcers are superficial type of corneal ulcers, but they do not heal fast and if at all they heal, they do so in a very poor manner and tend to recur. Also known a Indolent ulcers and Boxer Ulcers. They are formed by a defect in the basement membrane of the cornea and because of which there is lack of hemidesmosomal attachments.

 What are Melting ulcers?

Ulcers of the cornea which have a progressive loss of stroma which looks as if it is dissolving is known as Melting Ulcer. This is commonly caused by Pseudomonas infections and by some other types of bacteria or fungi. Proteases and collagenases are formed in the ulcer which give the "melting" appearance to the peripheral tissues and the process of melting is very fast in a way that complete stroma gets melted within 24 hours of initiation of infection.

 How does an ulcer in the eye get better?

To heal, the ulcer requires two things. Firstly, healthy cells and new blood vessels to supply blood. The surrounding healthy epithelial tissues migrate from the healthier part to the ulcerated part and grow in number by mitosis type of division after which blood is introduced to the ulcerated part by formation of new blood vessels from the conjunctiva. Superficial ulcers heal fast even by the plain introduction of blood. But the big, old ulcers require constant supply of blood so that white blood cells, inflammation controlling cells, the fibroblasts can reach the ulcer and then heal the ulcers within a weeks period.

References for this article on Corneal Ulcer

1. http://en.wikipedia.org/wiki/Corneal_ulcer

2. Retrieved from "http://en.wikipedia.org/w/index.php?title=Corneal_ulcer&oldid=49123371"