Corneal Disorders

Corneal Disorders

Dry eye

The continuous production and drainage of tears is important to the eye's health. Tears keep the eye moist, help wounds heal and protect against infection. The tear film smoothes the surface of the cornea giving it a polished appearance and helping visual clarity.

Dry eye is very common, especially in women after the menopause.

Causes

Tears are made mostly by the lacrimal gland (in the upper outer part of the eye socket). Tears leave the eye either by evaporation or drainage. The tear drainage system runs from the inner corner of both eyelids and drains into the nose. Most commonly, dry eyes occur with increasing age due reduced production by the lacrimal gland. It can also occur due to eyelid problems such as blepharitis when the tear quality is poor. Dry eyes can occur in climates with dry air, as well as with the use of some drugs, including antihistamines, nasal decongestants, tranquillisers and anti-depressant drugs. People with connective tissue diseases such as rheumatoid arthritis; can also develop dry eye. Dry eye is sometimes a symptom of Sjögren's syndrome, a disease that attacks the body's lubricating glands, causing dry eyes and dry mouth.

Signs & Symptoms

Patients with dry eye complain of chronic discomfort, usually described as a burning, gritty sensation. Some describe a scratchy or sandy feeling as if something is in the eye. Other symptoms include stinging, stringy discharge, heaviness, blurred vision or even watering (if the quality of the tears is poor). The eyes can become red and loose its shiny appearance. You might also see stringy mucus strands and filaments. The tear film on the lower eyelid maybe reduced. The tear break up time may be rapid.

Detection and Diagnosis

Adding a dye to the eye: fluorescein (orange) or rose bengal (red) may identify dry/damaged areas on the cornea. A Schirmer's test (the amount of moistening of a strip of blotting paper placed in contact with the inside of the lower eyelid) can measure the amount of tear production.

Treatment

The best treatment is frequent lubricating drops or artificial tears. They are generally available over the counter as drops. Sterile ointments are sometimes used at night, but they can make the vision misty first thing in the morning. Each patient will prefer different drops, and will need them at different frequencies - from once daily right up to every 15 minutes. The drops are cheaper to buy than a prescription charge - but are available on prescription if necessary. Using humidifiers, wearing wrap around glasses when outside and avoiding outside windy and dry conditions may aid relief. For people with severe cases of dry eye, temporary or permanent closure of the tear drains may be helpful. Some people even use swimming goggle type of protection to reduce evaporation.

Severe Dry eye patients need occlusion of puncta with punctal plugs. Recent drug cyclosprain (0.05%) drops have been found to be beneficial in improving tear formation. Autologus serum drops are especially helpful in healing of micro epithelial defects. Patients undergoing treatment should be taken up for cataract surgery under proper counseling.

Corneal Ulcer

A corneal ulcer forms when the surface of the cornea is damaged or compromised. Ulcers may be sterile (no infecting organisms) or infectious. The term infiltrate is also commonly used along with ulcer. Infiltrate refers to an immune response causing an accumulation of inflammatory cells in an area of the body where they don't normally belong.

To distinguish whether or not an ulcer is infectious is an important distinction for the physician to make and determines the course of treatment. Bacterial ulcers tend to be extremely painful and are typically associated with a break in the epithelium, the superficial layer of the cornea. In some cases, the inflammatory response involves the anterior chamber along with the cornea. Certain types of bacteria, such as Pseudomonas, are extremely aggressive and can cause severe damage and even blindness within 24-48 hours if left untreated.

Sterile infiltrates on the other hand, cause little if any pain. They are often found near the peripheral edge of the cornea and are not necessarily accompanied by a break in the epithelial layer of the cornea.

There are many causes of corneal ulcers. Mot of our patients get corneal epithelial injury while working in fields and get corneal ulcer. These patients have injury with vegetative foreign body and develop fungal Corneal Ulcer. Contact lens wearers (especially soft) have an increased risk of ulcers if they do not adhere to strict regimens for the cleaning, handling, and disinfection of their lenses and cases. Soft contact lenses are designed to have very high water content and can easily absorb bacteria and infecting organisms if not cared for properly. Pseudomonas is a common cause of corneal ulcer seen in those who wear contacts.

Bacterial ulcers may be associated with diseases that compromise the corneal surface, creating a window of opportunity for organisms to infect the cornea. Equally important are Corneal Ulcers caused by fungus. These ulcers need early diagnosis, a prompt institution of treatment as drugs used to treat fungal ulcers do not penetrate deeper into the eye. Patients with severely dry eyes, difficulty blinking, or are unable to care for themselves, are also at risk. Other causes of ulcers include: herpes simplex viral infections, inflammatory diseases, corneal abrasions or injuries, and other systemic diseases.

Signs and Symptoms

The symptoms associated with corneal ulcers depend on whether they are infectious or sterile, as well as the aggressiveness of the infecting organism.

  • Red eye
  • Severe pain (not in all cases)
  • Tearing
  • Discharge
  • White spot on the cornea, that depending on the severity of the ulcer, may not be visible with the naked eye
  • Light sensitivity

Detection and Diagnosis

Corneal ulcers are diagnosed with a careful examination using a slit lamp microscope. Special types of eye drops containing dye such as fluorescein may be instilled to highlight the ulcer, making it easier to detect.

If an infectious organism is suspected, the doctor performs corneal scraping and may order a culture. After numbing the eye with topical eye drops, cells are gently scraped from the corneal surface and tested to determine the infecting organism.

Treatment

The course of treatment depends on whether the ulcer is sterile or infectious. Bacterial ulcers require aggressive treatment. In some cases, antibacterial eye drops are used every 15 minutes. Steroid medications are avoided in cases of infectious ulcers. Some patients with severe ulcers may require hospitalization for IV antibiotics and around-the-clock therapy. Sterile ulcers are typically treated by reducing the eye's inflammatory response with steroid drops, anti-inflammatory drops, and antibiotics. Sterile ulcers leading to impending or actual corneal perforations are treated with a corneal glue. Patients having large corneal perforations or infective corneal perforations are treated by Tectonic Penetrating Keratoplasty.

Keratoconus

Keratoconus is a degenerative disease of the cornea that causes it to gradually thin andKeratoconus bulge into a cone-like shape. This shape prevents light from focusing precisely on the macula. As the disease progresses, the cone becomes more pronounced, causing vision to become blurred and distorted. Because of the cornea's irregular shape, patients with keratoconus are usually very nearsighted and have a high degree of astigmatism that is not correctable with glasses.

Keratoconus is sometimes an inherited problem that usually occurs in both eyes. The disease may occur in association with Vernal Catarrh (allergy), Down's Syndrome.

  • Signs and Symptoms
  • Nearsightedness
  • Astigmatism
  • Blurred vision - even when wearing glasses and contact lenses
  • Glare at night
  • Light sensitivity
  • Frequent prescription changes in glasses and contact lenses
  • Eye rubbing
Keratoconus

Detection and Diagnosis

Keratoconus is usually diagnosed when patients reach their 20's. For some, it may advance over several decades, for others, the progression may reach a certain point and stop.

Keratoconus is not usually visible to the naked eye until the later stages of the disease. In severe cases, the cone shape is visible to an observer when the patient looks down while the upper lid is lifted. When looking down, the lower lid is no longer shaped like an arc, but bows outward around the pointed cornea. This is called Munson's sign.

Special corneal testing called topography provides the doctor with detail about the cornea's shape and is used to detect and monitor the progression of the disease. A pachymeter may also be used to measure the thickness of the cornea.

Treatment

The first line of treatment for patients with keratoconus is to fit rigid gas permeable (RGP) contact lenses. Because this type of contact is not flexible, it creates a smooth, evenly shaped surface to see through. However, because of the cornea's irregular shape, these lenses can be very challenging to fit. This process often requires a great deal of time and patience. In case the disease progresses, collagen cross linking with Topical Riboflavin Sensitization is performed. This is a new treatment modality and may stabilize Keratoconus in 70-80% cases.

When vision deteriorates to the point that contact lenses no longer provide satisfactory vision, corneal transplant may be necessary to replace the diseased cornea with a healthy one.