eye health

Corneal abrasion

What is Corenal Abrasion

A corneal abrasion is a lesion of the cornea, the transparent membrane located in the anterior part of the eye that covers the iris and the pupil allowing the passage of light towards the internal structures of the eye.

Accidental contact with dust, sand, wood chips or metal particles can scratch or cut the cornea. Usually, the lesion is superficial, and, therefore, is called "abrasion".

When the cornea is damaged, a gritty sensation can be felt in the eye, pain, redness, burning, tearing, photophobia, blurred vision and headache. Corneal abrasion can heal within 24-72 hours and rarely progresses to ulcer, erosion or infection.

The initial treatment should be symptomatic and include: the removal of foreign bodies, analgesia with topical or oral non-steroidal anti-inflammatory drugs and the prescription of antibiotics. Corneal abrasions can often be avoided by using protective glasses when performing activities that expose the eyes to injury.

Cornea

Functions and structure

The cornea is an organized group of cells, structurally in continuity with the sclera (white part of the eye). This thin membrane has three important functions in vision: protection, filtration of some ultraviolet wavelengths and refraction (the cornea is responsible for 65-75% of the eye's ability to focus light on the retina). To allow the correct passage of light towards the internal structures of the eye, the cornea must be totally transparent. For this reason it is not vascularized and draws oxygen and nourishment from tears (superficial cells of the epithelium) and from the aqueous humor that fills the anterior chamber (deep cells). Instead, there are numerous free nerve endings, so the cornea is one of the most sensitive parts of the entire eye. All these aspects are of considerable importance, since a serious corneal lesion can cause blindness even if other parts of the eye are perfectly normal.

Causes

Typically, corneal abrasions are the result of a direct injury.

The most common causes include:

  • A foreign body enters the eye and remains locked inside the upper eyelid (example: eyelashes, dust, sand or ash);
  • Something strikes the eye (example: a branch of a tree, the edge of a piece of paper, a fingernail, etc.);
  • Wear contact lenses longer than recommended;
  • Rub your eyes hard;
  • Some eye conditions, including trachoma or other infections.

People of all ages can suffer corneal damage. In some cases, the professional activity can increase the risk, as in the case of farmers, carpenters and construction workers exposed to environments that contain particles dispersed in the air, such as dust, sawdust and sand.

Even materials that reach a high speed can penetrate the eye and cause even deeper injuries: a small metal fragment, for example, can hit a person while using a grinder without protective glasses.

Symptoms

Symptoms vary from person to person, depending on the extent of the injury. Corneal abrasions, except in cases caused by extensive chemical burns or ultraviolet light, usually affect only one eye.

In the case of corneal abrasion, the following symptoms may occur:

  • Pain, which can worsen with the movement of extraocular muscles;
  • Photophobia (light sensitivity);
  • Headache;
  • Blepharospasm;
  • Swollen eyelids;
  • Pupil dilation;
  • Excessive watery eyes;
  • Blurred vision or altered vision;
  • Eye pain when exposed to bright light;
  • Redness of the sclera;
  • Feeling that there is something inside the eye. This sensation sometimes develops after a few hours, rather than immediately after the injury.

Diagnosis

In case of suspected corneal abrasion the ophthalmologist should be consulted for a correct diagnosis. During the eye exam, the doctor will ask the patient some questions about the daily activities performed, the possible causes of the injury, the symptoms experienced and the presence of other current or previous eye diseases, such as glaucoma.

Anesthetic eye drops are used to temporarily relieve pain. To accurately diagnose the condition, a few eye drops containing fluorescein (yellow-orange in color) are used in combination with a cobalt-blue filtered light, which enhances corneal abrasion (evident due to the green color it assumes).

Complications

  • Corneal abrasion complications can include scarring and ulcers in the cornea.
  • The presence of corneal scars can cause opacity of the carnea (leucoma).
  • Injuries caused by plant material (such as a pine needle) can cause delayed inflammation inside the eye (iritis).
  • A corneal infection can spread to other parts of the eye and lead to temporary or permanent changes in vision.
  • Occasionally, the cured epithelium may adhere poorly to the underlying basement membrane, giving rise to recurrent corneal erosions.

Treatment

Fortunately, most corneal abrasions heal completely within 24-48 hours of injury, so that minor injuries do not need treatment. However, the most indicated treatment depends strictly on the cause and the severity of the injury; for example, if the abrasion was caused by a branch of a tree, the ophthalmologist can prescribe an antibiotic to prevent an infection or a corneal ulcer; if, on the other hand, abrasion is the result of a particle of dust flying into the eye, it may be sufficient to wash the area with clean water.

Most patients must be re-examined within the next 24 hours and if the abrasion is not completely resolved, a further visit will be necessary after 3-4 days. Other causes may take longer to heal or require more complex treatment; for example, if the abrasion is very serious, a corneal transplant may be necessary, which removes the damaged surface to replace it with a new one.

The immediate measures that can be taken in case of minor corneal abrasion are:

  • Rinse the eye with clean water (or use a saline solution, if available) to remove small particles of dust or sand. It is possible to wash the eye by tilting the head back and pouring water into the open eye.
  • Artificial tears or lubricating eye drops can relieve temporary discomfort.

In the case of corneal abrasion, it is still advisable to consult a doctor immediately. Meanwhile, it is important to avoid certain actions that can aggravate the damage:

  • Do not attempt to remove an object that has penetrated deeply into the eyeball, even if it is large in size and prevents the eye from closing.
  • Do not rub your eyes after an injury. Touching or pressing the eye can make corneal abrasion worse.
  • Do not touch the eyeball with cotton swabs, tweezers or other tools, as such maneuvers can aggravate the injury.

The ophthalmologist can treat the specific condition of the eye based on the diagnosis:

  • Eye drops or antibiotic ointments may be prescribed. In some cases, the ophthalmologist can indicate eye drops based on corticosteroids or non-steroidal anti-inflammatory drugs, to reduce inflammation and the risk of scarring.
  • Depending on the nature of the injury, a tetanus vaccination may be recommended, especially if the immunization status is not up to date (for example, if the foreign body leaves a rust residue).
  • Although anesthetic eye drops are administered at the time of the visit to immediately relieve eye pain, these drops are not prescribed for home use, as they can interfere with the natural healing process. Alternatively, the ophthalmologist can indicate which painkillers to take orally.

After the eye examination, the patient should rest with his eyes closed to facilitate recovery, so avoid activities such as reading or driving. Wearing sunglasses can help alleviate some corneal abrasion symptoms during healing.