Corneal Ulcer – Causes, Pathogenesis, Symptoms, Prognosis, Treatment

By Dr Raghuram Y.S. MD (Ay) & Dr Manasa, B.A.M.S
Cornea is a part of the eye. It is the transparent front part of the eye and constitutes the first layer of the eye along with the sclera. It covers the iris, pupil and anterior chamber, parts of the second layer of the eye. The black of the eye is the colour of the iris seen through the cornea. The cornea along with the anterior chamber and lens refracts light. Cornea alone accounts for approximately 2/3 of the eye’s total optic power.
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The focus of cornea is fixed even as it contributes to most of the focusing power of the eye. Refocusing the light to have a better view of near objects is called accommodation. This accommodation is accomplished by changing the geometry of the lens and happens with synchronization between cornea and lens.

The medical terms related to the cornea often start with the prefix ‘kerat’. In Greek, kerat means horn.
Corneal ulcer is one of the common corneal disorders. It is an inflammatory or infective condition of the cornea. It involves disruption the epithelial layer of the cornea with involvement of the corneal stroma.
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Introduction

Corneal ulcer is an open ulcer formed over the cornea. There is loss of corneal tissue and is often associated with inflammation. A group of disease processes occurring in the cornea leading to corneal ulceration is termed as ulcerative keratitis. The same term is used to define the inflammation that accompanies corneal ulceration.

Most of the corneal ulcers are caused due to infection. Infection of cornea includes bacterial and viral etiologies. Non-infectious ulcers also occur. When it happens it is usually due to chemical burns or autoimmune, neuro-trophic, toxic or other causes.

Corneal ulcer can often cause permanent impairment of vision or perforation. Therefore it is considered as an ophthalmologic emergency.
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Causes of corneal ulcers

Infection – Infection, mainly bacterial origin, viral or fungal infection also cause corneal ulcers. Most corneal ulcers are caused by infections.
Bacterial infections are common in people wearing contact lenses.
Viral infections are also possible causes of corneal ulcers. Example – Herpes simplex virus or varicella virus etc.
Fungal infections are unusual causes of corneal ulcers. This may happen after injury with organic materials like twigs, branches etc.
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Use of contact lenses – corneal ulcers is common in users of contact lenses. People wearing contact lenses are at an increased risk of corneal ulcers. The risk increases tenfold when one uses extended wear soft contact lenses overnight. Scratches on the edge of the contact lens, tiny part of dirt trapped underneath the contact lens, bacteria on lens or in cleaning solutions getting trapped under surface of the lens and wearing lenses for extended periods of time leading to blockage of oxygen to the cornea, all these can damage the cornea causing corneal ulcers. The physician may consider the type of contact lens and lens solution and also contact lens hygiene.
Trauma – Tiny tears to the cornea from trauma, scratches or particles (sand, glass, pieces of steel etc) and contact with other foreign bodies. The damage caused in this way paves way for bacteria to invade and cause a serious corneal ulcer.
Disorders causing dry eyes – These disorders can leave our eyes without the germ fighting protection of tears. This in turn causes ulcers.
Disorders which afflict the eyelid – These diseases prevent our eyes from closing completely. This will lead to dryness of cornea and will make it vulnerable to the ulcers. Example – Bell’s palsy.
Chemical burns – or burns due to other caustic solution splashes tend to injure the cornea.
Use of medications – including systemic and ocular medications, particularly steroids shall be considered.
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Past medical history –

  • Previous history of ocular disease or eye surgery
  • Diabetes mellitus
  • History of HIV or other immunodeficiency disorders
  • Tear film deficiencies
  • Collagen vascular diseases – Example, Rheumatoid Arthritis, Wegener granulomatosis
  • Exposure to sulphur or mustard
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Social causes – Smoking is an important risk factor for corneal ulcer.

Other causes

Patho-physiology


Most of the corneal ulcers are infectious. The ulcers are occasionally sterile. Most of the corneal infections and infectious keratitis are considered to be caused by bacterial infection until proved otherwise.

How are bacterial corneal ulcers caused?
Break in epithelium – A break in the corneal epithelium providing entry for the bacteria usually causes bacterial corneal ulcers.
The break in epithelium is usually preceded by a traumatic episode. It may include –

Contact lenses and bacterial infection – Occurrence of corneal ulcers in high proportions has been linked with increased use of soft contact lenses. This is particularly due to the infection from Pseudomonas aeruginosa. Apart from this bacterium, Staphylococcus aureus, Streptococcus pneumonia and Enterobacteriaceae are the other bacteria that are isolates cultured form patients with keratitis. Similarly, Klebsiella pneumonia mucoid phenotype and its ability to form a bio-film may be important in the production of ulceration of cornea.
Viral infection – Herpes simplex and varicella zoster virus can cause infectious keratitis.
Fungi – Fungi of mainly Fusarium and Candida species, and parasitic ameba are found in small number of patients. When corneal ulcer is due to these, the symptoms are more severe.
Rheumatoid Arthritis – Peripheral ulcerative keratitis (PUK) is a complication of rheumatoid arthritis. This would lead to corneal melt i.e. rapid destruction of cornea and perforation of cornea with loss of vision. Mooren Ulcer – It is an idiopathic ulceration of the peripheral part of cornea. It may result from an autoimmune reaction. It may also be associated with Hepatitis C Virus. It is a rapidly progressive and painful ulcerative keratitis. After affecting the peripheral part of cornea initially, this ulcer may spread circumferentially and then centrally. This condition can be diagnosed only in the absence of an infectious or systemic cause of corneal ulcers.
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Symptoms

  • Redness of eyelid and conjunctiva
  • Muco-purulent discharges from the eye
  • Sensation of foreign bodies in the eye
  • Tears
  • Diminished vision
  • Sensitivity of light / pain when looking at bright light
  • Pain in the eye
  • Blurring of vision
  • Swollen eyelids
  • White round spot on the cornea that is visible with the naked eye (when the ulcer is very large)
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Diagnosis


Physical and eye examination – The physical examination may give clues towards likelihood of infection, to access severity, risks of perforation and vision loss. The physical examination includes evaluation of visual acuity, external examination and slit lamp examination.
Gross examination includes examination of eyelids, surface of eye, pupils, extraocular muscles and fundi. This would reveal any associated inflammation which might be causing corneal ulcers. When there is inflammation, the eye is often erythematous and ciliary injection is always present. Pupil constriction may be present secondary to ciliary spasm and iritis. Purulent exudates may be seen in conjunctiva sac or on the ulcer surface. There will be infiltration of stroma resulting in whitish opacity of cornea.
Slit Lamp Examination – is one of the important examinations which should be compulsorily done in corneal ulcers. This helps in studying the ulcer. An anterior chamber reaction is often seen. This examination often reveals findings of iritis and hypopyon (accumulation of inflammatory cells in anterior chamber). This examination is used to access corneal epithelium, corneal stroma, corneal endothelium, corneal or sclera foreign bodies, signs of corneal dystrophies, previous corneal inflammation, signs of previous surgery and anterior chamber.
Fluorescein staining of the cornea – provides additional information such as presence of dendrites, loose or exposed sutures, foreign body and any epithelial defects. It may also reveal a dendritic ulcer or herpes simplex virus infection.
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Other Investigations
Culture – indicated in

Risk factors –

  • Use of contact lens, especially overnight use of lens
  • HIV infection
  • Trauma
  • Ocular surface disease
  • Ocular surgery
  • Older age
  • Male gender
  • Smoking
  • Low socioeconomic conditions
  • Inadequate hygiene and maintenance of contact lens
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Complications

Prognosis of corneal ulcers
Corneal ulcers should show day to day improvement and should heal with proper therapies. If there is no healing or if the ulcers extend, an alternate diagnosis and different line of treatment shall be considered.
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Epidemiology of corneal ulcers
Approximately 25,000 Americans develop infectious keratitis annually. Annual incidence of contact lens associated microbial keratitis – 2-4 infections per 10,000 users of soft contact lenses approximately.

Study from UK –
Factors associated with an increased corneal invasive event –

Age – Injury or infection of cornea can occur at any age. According to bimodal distribution, the first group of patients less than 30 years of age, mostly wear contact lenses or sustain ocular trauma. The second groups of patients more than 50 years of age are those who are more likely to undergo eye surgery.

Sex (Studies in UK)

Morbidity – Probable consequences of corneal ulcers are corneal scarring and loss of vision.
Contact lenses – Infectious keratitis is significantly more common in those who use contact lenses. It is 8 times more in those who sleep wearing contact lenses compared to those who use lenses only during waking time.

Self-care and home remedies


Corneal ulcer is a medical emergency. It should not be dealt with home remedies. But some measures need to be taken to worsen the progression of ulcer and to take care of the eye.
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  • Remove your contact lens immediately
  • Apply cool compresses to the affected eye
  • Take care not to touch or rub your eye with your fingers
  • Wash your hands often and dry them with a clean towel before touching your eye. This limits spread of infection.
  • Take over-the-counter pain medications such as acetaminophen or ibuprofen with the consent and prescription of your physician.

Prevention

  • Wear eye protection, especially when you are exposed to small particles that can enter your eye
  • Use artificial teardrops to enable proper lubrication of the eyes if you have dry eyes or if your eyelids do not close completely
  • Be careful about the way you clean and wear your lenses
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Care about use of lenses

  • Wash your hand before handling the lenses, never use saliva to lubricate or clean your lenses
  • Every evening, make sure to remove your lenses and clean them carefully. Do not use tap water to clean the lenses.
  • Never sleep wearing contact lenses.
  • Store the lenses in disinfecting solutions in your eyes.
  • Remove lenses whenever your eyes are irritated. Leave them out until your eyes feel better.
  • Keep cleaning your contact lens case regularly
  • Discard and replace the contact lenses at the interval specified by your doctor
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A corneal ulcer is a true emergency. When it is not treated, the ulcer can tend to spread to the rest of your eyeball. Consequentially you can become partially or completely blind in a short period of time. It may also cause perforation of cornea, scarring, cataracts and glaucoma. When it is promptly treated, the corneal ulcers should improve within 2-3 weeks. If scars from previous corneal ulcers impair vision, a corneal transplant may be needed to restore normal vision.
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When to seek medical care?
One should, without wasting time, consult a doctor and seek medical care if the below mentioned are observed in corneal ulcer –

Treatment


Proper approach and appropriate care of a corneal ulcer starts and depends on a proper assessment of risk of loss of vision and perforation. Whenever a corneal ulcer is identified it is better to consult a doctor, an ophthalmologist from emergency department to be precise, on first hand, without any delay. Corneal ulcer is always considered as an emergency since it tends to impair vision and cause perforation.
Goals of pharmacotherapy – is to reduce morbidity and prevent complications.
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Antibiotic therapy –

  • The therapy must cover all likely pathogens. Commonly used ones are Cefazolin (first generation cephalosporin), Gentamicin (aminoglycocide), Erythromycin, Ciprofloxacin etc.
  • Fluoroquinolone eye drops should be used in low risk and medium risk of vision loss and addition of tobramycin or ciprofloxacin ointment in contact lens wearers

Antivirals, ophthalmic – to treat viral infections topical instillation of antiviral medications should be used, example, Trifluridine, Ganciclovir, etc
Fungal infection – broad spectrum anti-fungal drug should be used when fungal infection is suspected, Example, Natamycin, Voriconazole, Miconazole, Ketoconazole, Fluconazole etc
Non-steroidal anti-inflammatory drugs (NSAIDs) – to treat pain, example, Ibuprofen, Naproxen, Ketoprofen, Diclofenac etc
Analgesics / oral pain medications – for pain control should be used when pain is associated with corneal ulcer, example, Oxycodone, Acetaminophen, Morphine, Codeine, Aspirin etc.
Avoid contact lens – use of contact lens should be avoided until advised by ophthalmologist.
Anesthetics – These are indicated for pain relief and for conjunctiva and corneal scrapings.
Cycloplegics – are the agents used to relax ciliary muscle spasm which can cause deep aching pain and photophobia. Example – Cyclopentolate, atropine ophthalmic etc.
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Surgery
Surgery is an option if the ulcer cannot be treated by medications or if there is a threat for corneal perforation. Many times an emergency surgical procedure or a corneal transplant may be needed immediately.
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Ayurveda correlation


A condition named ‘Savrana Shukra / Savrana Shukla’ explained in Ayurvedic texts have often been compared to corneal ulcer. This is explained in the context of krishnagata rogas i.e. diseases afflicting the cornea in this context.
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It is said to be caused by vitiated blood and is incurable in nature. In this condition, it is explained that an ulcer appearing like a needle puncture / looking like the tip of the needle is formed deep inside the cornea and is hardly seen. Hot tears flow out of the eye and are associated with pain in the eye.
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