Corneal Disorders: Conditions that affect the cornea, and the clear outer layer of the eye. The cornea can often repair itself after injury or disease, but more serious conditions — infections, degenerative diseases, deterioration — need treatment. Cornea serves as a barrier against dirt, germs and other particles that can harm the eye’s delicate components. The cornea also filters out some amounts of the sun’s ultraviolet light.
It includes disorder of
- Corneal ulcer
- Herpes simplex keratitis
- Herpes zoster ophthalmicus
- Interstitial keratitis
- Corneal ulcer (Keratitis)
Corneal ulcer (keratitis) is an erosion or an open sore on the cornea which is the thin clear structure of the eye that refracts light. If the cornea becomes inflamed due to infection or injury, an ulcer may develop.
Symptoms of Corneal Ulcer (Keratitis):
- Gritty sensation
- Blurry vision
- Light sensitivity
Causes of Corneal Ulcer (Keratitis):
The causes of a corneal ulcer (keratitis) are:
• Contact lenses – contaminated solution, poor hygiene, over usage, sleeping with contact lenses on, using tap water or swimming with contact lens on. Wearing lenses for extended periods blocks the supply of oxygen to the cornea, making it susceptible to infections.
• Trauma – chemical injury, thermal burn, bee sting, animal tail, makeup or vegetative matter like the branch of a tree, sugarcane
• Post-surgery – delayed healing, loose sutures
• Lid deformities – inward or outward turning of eyelid, misdirection of eyelashes constantly rubbing over the cornea, incomplete closure of eyes
• Decreased nerve supply to the cornea – seen in diabetics and bell’s palsy patients
• Allergic conjunctivitis
• Vitamin A deficiency
• Prolonged use of eye drops – corticosteroids
• Severe dry eyes – caused by medical conditions like diabetes mellitus, thyroid disorder, vitamin A deficiency, rheumatoid arthritis, Sjogren syndrome, Stevens-Johnson syndrome
Risk factors of Corneal ulcer (keratitis):
- Injury or chemical burns
- Eyelid disorders that prevent proper functioning of the eyelid
- Dry eyes
- Contact lens wearers
- people who have or have had cold sores, chicken pox or shingles
- Abuse of steroid eye drops
- Do not sleep with contact lenses on
- Do not overuse contact lenses
- Wash your hands before putting the lenses
- Advised to use daily disposable lenses
- Do not use tap water as lens solution
- While riding a bike, wear eye protection or visor to prevent foreign bodies from entering the eye.
- Do not rub your eye
- Proper instillation of eye drops. The nozzle of the eye drop bottle should not touch the eye or the finger
- Use artificial tears in case of dry eyes
- Wear protective eyewear when working with wood or metals, especially when using a grinding wheel, hammering on metal, or welding.
- Do not use over-the-counter eye drops.
The ulcer is carefully examined on the slit lamp microscopy for the analysis of size, shape, margins, sensation, depth, inflammatory reaction, hypopyon and presence of any foreign body. A fluorescein dye is used to stain the ulcera to enhance the features and check for any leak.
Debridement of the ulcer is essential for microbiological evaluation to identify the causative organism. After putting an anesthetic drop in the eye, the margins and the base of the ulcer is scraped with the help of a sterile disposable blade or needle. These samples are stained and cultured to identify and isolate the organism. Scraping the ulcer also helps in better absorption of the eyedrops.
Depending on the cause of ulcer, patient will probably get antibiotic, antiviral, or antifungal eye drops. Patient might need to use these as often as once an hour for several days.
To treat pain, doctor may also give oral painkillers or drops to widen (dilate) the pupil.
If medications don’t help or if the ulcer is severe, patient might need a corneal transplant. Doctor takes out the cornea and replaces it with a healthy one from another person.
2. Herpes simplex keratitis
Herpes simplex keratitis is corneal infection with herpes simplex virus. It may involve the iris. Symptoms and signs include foreign body sensation, lacrimation, photophobia, and conjunctival hyperemia. Recurrences are common and may lead to corneal hypoesthesia, ulceration, permanent scarring, opacification, thinning of the corneal stroma, and decreased vision. Diagnosis is based on the characteristic dendritic corneal ulcer and sometimes viral culture. Treatment is with topical or systemic antiviral drugs.
Symptoms and Signs of Herpes Simplex Keratitis
The initial (primary) infection is usually nonspecific self-limiting conjunctivitis, often in early childhood and usually without corneal involvement. If the cornea is involved, symptoms include foreign body sensation, lacrimation, photophobia, and conjunctival hyperemia. Sometimes vesicular blepharitis (blisters on the eyelid) follows, symptoms worsen, vision blurs, and blisters break down and ulcerate, then resolve without scarring in about a week.
Recurrent ocular herpes affects the cornea. Three main types of herpes simplex keratitis are
- Epithelial keratitis (dendritic keratitis)
- Disciform keratitis (localized endotheliitis)
- Stromal keratitis
Reactivation of latent herpes simplex can be triggered by UV light exposure (eg, intense sunlight, corneal cross-linking [an ultraviolet light treatment that stiffens the cornea], or laser refractive procedures), fever, menstruation, significant systemic physical stress (eg, burns or multiple fractures), immunosuppression, or use of glucocorticoids (topical ophthalmic, periocular injection, intraocular injection, or systemic). Recurrences usually take the form of epithelial keratitis (also called dendritic keratitis), with tearing, foreign body sensation, and a characteristic branching (dendritic or serpentine) lesion of the corneal epithelium with bulb-like terminals that stain with fluorescein. Multiple recurrences may result in corneal hypoesthesia or anesthesia, ulceration, permanent scarring, opacification, thinning of the corneal stroma, and decreased vision.
Diagnosis of Herpes Simplex Keratitis
HSV keratitis is usually diagnosed based on a patient’s health history and findings from an eye exam. Lab testing is not usually necessary, but certain lab tests may further help to confirm HSV-1.
Treatment of Herpes Simplex Keratitis
The treatment of HSV keratitis usually involves medicine, including eye drops or antiviral medications taken by mouth. Such as
• Topical ganciclovir or trifluridine
• Oral or IV acyclovir or valacyclovir
• For stromal involvement or uveitis, topical corticosteroids in addition to antiviral drugs
Surgery is rarely necessary but may be considered if scarring on the eye from HSV keratitis causes vision problems. Each case of HSV keratitis is unique, and an eye doctor should determine the best treatment for each patient. While some treatments can greatly lower the severity and recurrence of symptoms, there is no cure for HSV.