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Corneal abrasions: How to prevent a painful tear

May 3, 2012

Roshni Ranjit BA, BS1, Sejal Shah MD2


1 University of South Florida College of Medicine, Tampa, FL
2 University of South Florida Eye Institute, University of South Florida Morsani College of Medicine, Tampa, FL

The cornea is a transparent anterior (front) wall of the eye. It is avascular (without blood flow) and comprised of a highly organized group of cells and proteins allowing for its transparency. The tear-air interface in conjunction with the cornea provides sixty seven percent of the refractive (light ray bending) power of the eye. With the addition of the lens power, images are able to be focused onto the retina (tissue on the inside of the eye). The projected image allows the brain to process the image so that it can be seen and interpreted correctly. Additionally, the cornea provides a barrier for protection and filtration of the UV rays. It is nourished by tears on the surface of the cornea, which provide nutrients and oxygen, and aqueous humor (fluid within the eye) on the inner surface which is produced by the ciliary body inside the eye.

A corneal abrasion describes a condition in which there is loss of cells from the corneal epithelium (surface layer). Any injury to the cornea can affect vision since it causes a change in the smooth surface of the cornea and therefore alters the rays of incoming light. Most corneal abrasion injuries are preventable and occur most often in high risk occupations like miners, woodworkers, metal workers ,landscapers and/or in those who enjoy contact sports like hockey, lacrosse, or racquetball.

Corneal abrasions are common among men and women, with an annual incidence in the workplace of 15/1000 employees among US autoworkers. This accounted for six percent of the total injuries. Of these patients, eighty-seven percent were related to corneal foreign body (piece of something or non anatomic object on the eye surface), and thirty-three percent were unable to resume their work for at least 1 day due to the injury. It was found that in primary care clinics, eye complaints accounted for two percent of visits. Eight percent of those visits were due to traumatic and/or foreign body injuries. Contact lens wearers are at a higher risk of developing corneal injury due to complications related to improper contact lens use. Contact lens injuries can range from simple abrasions to complicated ulcers that may require a corneal transplant in the future. Soft, extended wear-lenses have been associated with a 10 to 15 fold increase in corneal ulcers.

Corneal abrasions can be classified into several categories: Traumatic, Foreign Body Related, Contact Lens Related, or Spontaneous.

Traumatic corneal abrasion injuries occur due to a mechanical disturbance of the corneal surface leaving a defect in the corneal epithelium. They are often caused by fingernail scratches, paw scratches, pieces of paper or cardboard, make up applicators, tree branches or leaves, of by a foreign body that is wedged under the eye lid.

Foreign body related corneal abrasions occur from debris left behind after the removal or spontaneous dislodging of a corneal foreign body. Commonly occur due to pieces of rust, wood, glass, plastic, fiberglass, or vegetable material that have become lodged in the cornea. High-speed particles from welding or sanding can also cause serious damage and permanent loss of vision due to corneal injury. Contact lens related corneal abrasions occur because of defects in the corneal epithelium due to debris left behind from the removal of over-worn or improper fitting contact lenses. Without an effective barrier, infectious processes can then gain access and cause further damage. .

Spontaneous defects in the corneal epithelium may occur from eyes that have previously suffered from corneal trauma or that have an underlying defect in their corneal membrane.

Corneal abrasions often present as a foreign body sensation that is very uncomfortable and painful. Other symptoms include uncontrollable tearing of the eyes, blurred vision, eye pain with light, or as eye muscle spasms. The reason that corneal abrasions are so painful is because the cornea has many sensory pain fibers. For this reason people are often times unable to work, drive, read, or sleep due to the excruciating pain associated with the corneal abrasion injury.

Because corneal injuries can lead to permanent vision loss, it is important to understand ways to prevent this injury. Wearing sunglasses can help reduce the risk of corneal injury by providing a mechanical barrier and by reducing UV sun damage. It is important to wear protective eye gear especially when playing sports or in situations where objects can enter the eye at high speeds. Providing a physical barrier protection from airborne debris like sand, sawdust, metal, tree branches, sports balls, fingernails etc. is essential in preventing corneal injury. Wearing sunglasses while hiking or while participating in outdoor activities provides protection from windblown objects and/or foreign body penetration. When using a grinding wheel, hammering on metal, sandblasting, or wood chipping protective eye-gear should be worn at all times to prevent a compromise of the corneal membrane. Wearing protective eye gear to block UV radiation when in bright sunlight for long periods of time is essential in the water, light sand, or snow. This is because strong reflective rays in combination with direct sunlight can cause corneal flash burns leading to potential irreversible vision loss.

Successful treatment options recommended by ophthalmologists include eye patches, topical antibiotics, and mydriatic (pupil dilating) agents in addition to topical and/or oral analgesics (pain meds). While corneal abrasions often heal within 24-48 hours after injury, each injury should be taken very seriously because some injuries can heal poorly and recur. As mentioned above, a defect in the barrier of the corneal epithelium allows a gateway for outside organisms (bacteria, virus, etc...) possibly leading to a corneal ulcer and vision loss.

References

1.American Academy of Ophthalmology, Corneal Abrasion.
2. Edwards RS. Ophthalmic emergencies in a district general hospital casualty department. Br J Ophthalmol 1987; 71:938.
3.Ewald M, Hammersmith KM. Review of diagnosis and management of recurrent erosion syndrome. Curr Opin Ophthalmol. 2009 Jul;20(4):287-91.
4. Schein OD, Glynn RJ, Poggio EC, Seddon JM, Kenyon KR. The relative risk of ulcerative keratitis among users of daily-wear and extended-wear soft contact lenses. A case-control study. Microbial Keratitis Study Group. N Engl J Med. 1989;321:773-8
5.Shields T, Sloan PD. A comparison of eye problems in primary care and ophthalmology practices. Fam Med. 1991;23:544-546.
6.Weaver CS, Terrell KM. Evidence-based emergency medicine. Update: do ophthalmic nonsteroidal anti-inflammatory drugs reduce the pain associated with simple corneal abrasion without delaying healing? Ann Emerg Med. 2003;41:134-40
7.Wong TY, Lincoln A, Tielsch JM, et al. The epidemiology of ocular injury in a major US automobile corporation. Eye. 1998;12:870-874.

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