Corneal abrasion is probably the most common eye injury and perhaps one of the most neglected. It occurs because of a disruption in the integrity of the corneal epithelium or because the corneal surface scraped away or denuded as a result of physical external forces. Corneal epithelial abrasions can be small or large (see the images below).
Corneal abrasions usually heal rapidly, without serious sequelae. Consequently, they are often considered of little consequence. However, deep corneal involvement may result in facet formation in the epithelium or scar formation in the stroma.
Corneal abrasions occur in any situation that causes epithelial compromise. Examples include corneal or epithelial disease (eg, dry eye), superficial corneal injury or ocular injuries (eg, those due to foreign bodies), and contact lens wear (eg, daily disposable soft lenses, extended-wear soft lenses, gas-permeable lenses, hard polymethylmethacrylate lenses). Spontaneous corneal abrasions may be associated with map-dot-fingerprint dystrophy or recurrent corneal erosion syndrome.
A traumatic corneal abrasion is the classic corneal abrasion in which mechanical trauma to the eye results in a defect in the epithelial surface. Common causes of traumatic corneal abrasions include the following:
Foreign body–related abrasions are defects in the corneal epithelium that are left behind after the removal of or spontaneous dislodgement of a corneal foreign body. Foreign body abrasions are typically caused by pieces of rust, wood, glass, plastic, fiberglass, or vegetable material that have become embedded in the cornea.
Contact lens–related abrasions are defects in the corneal epithelium that are left behind after the removal of an overworn, improperly fitting, or improperly cleaned contact lens. In these cases, the mechanical insult is not from external trauma but rather from a foreign body that is associated with specific pathogens.
Spontaneous defects in the corneal epithelium may occur with no immediate antecedent injury or foreign body. Eyes that have suffered a previous traumatic abrasion or eyes that have an underlying defect in the corneal epithelium are prone to this problem.
The diagnosis of corneal abrasion can be confirmed with slitlamp examination and fluorescein instillation (see Workup). Prophylactic topical antibiotics are given in patients with abrasions from contact lenses, who are at increased risk for infected corneal ulcers, but many emergency physicians have stopped using these agents for minor injuries. Patching the eye is a traditional measure, but it is not supported by research and should not be performed in patients at high risk of eye infection. Pain relief is important. (See Treatment.)
For patient education information, see the Eye and Vision Center, as well as Corneal Abrasion; Foreign Body, Eye; and Eye Injuries.
The cornea is a transparent cover over the anterior part of the eye that serves several purposes: protection, refraction, and filtration of some ultraviolet light. It has no blood vessels and receives nutrients through tears as well as from the aqueous humor. It is innervated primarily by the ophthalmic division of the trigeminal nerve as well as the oculomotor nerve.
The cornea is composed of the following 5 layers (anterior to posterior):
A corneal abrasion is a defect in the surface of the cornea that is limited to the most superficial layer, the epithelium, and does not penetrate the Bowman membrane. In some cases, the bulbar conjunctiva is also involved. Corneal abrasion results from physical or chemical trauma. Severe corneal injuries can also involve the deeper, thicker stromal layer; in this situation, the term corneal ulcer may be used.
The conjunctival response to corneal wounding has been known since 1944, when Mann first observed that peripheral corneal abrasions heal by the sliding of limbal cells to cover the epithelial defect. This response is split into 2 phases: (1) the response of the limbal epithelium, which is the source of the corneal epithelial stem cells, and (2) the response of the conjunctival epithelium itself.
Under normal circumstances, the limbal epithelium acts as a barrier and exerts an inhibitory growth pressure that prevents the migration of conjunctival epithelial cells onto the cornea. Like the rest of the surface of the body, the conjunctiva and the cornea are in a constant state of turnover. Corneal epithelial cells are continuously shed into the tear pool, and they are simultaneously replenished by cells moving centrally from the limbus and anteriorly from the basal layer of the epithelium.
Movement from the basal to superficial layers is relatively rapid, requiring 7-10 days. However, movement from the limbus to the center of the cornea is slow and may require months.
This normal physiologic process is exaggerated in the case of a corneal abrasion. During corneal healing of a lesion, corneal epithelial cells become flattened, they spread, and they move across the defect until they cover it completely. Cell proliferation, which is independent of cell migration, begins approximately 24 hours after injury.
Stem cells from the limbus also respond by proliferating to give rise to daughter cells called transient amplifying cells. These cells migrate to heal the corneal defect and proliferate to replenish the wounded area. The observation of limbal pigment migrating onto the clear cornea provides additional evidence of this process.
The concept that the limbal cells form a barrier to conjunctival cells was supported further by the observation that rabbit eyes treated for 120 seconds with N -heptanal, which removed the corneal and conjunctival epithelium but left the limbal basal cells intact, healed with the corneal epithelium and had unvascularized corneas. However, when the entire limbal zone was surgically removed along with N -heptanal treatment, corneal vascularization and conjunctivalization was observed.
Demonstration of the centripetal migration of limbal cells (marked by India ink) provided more direct evidence of this concept. These cells migrate in masses as a continuous, coherent sheet, with most cells retaining their positions relative to each other, much like the movement of a herd of cattle.
Rearrangement of intracellular actin filaments plays a role in movement. Cell migration can be inhibited by blocking polymerization of actin, indicating that actin filaments actively participate in the mechanism of cell motion. Some authors believe that conjunctival and limbal epithelial cells may contribute to the regeneration of corneal epithelium. Marked proliferative responses in the conjunctiva after a central corneal epithelium abrasion have been described.
Why the conjunctival epithelium should proliferate in response to a central corneal wound is unknown. One possibility is that the proliferation replenishes the number of goblet cells, which decreases by up to 50% after corneal wounding. However, proliferation occurs at high levels in the bulbar conjunctiva, which contains few if any goblet cells. The apparent decrease in cell number is more likely the result of mucin secretion rather than actual loss of goblet cells.
Alternatively, conjunctival cells may migrate into the limbus or cornea to help replenish the wound area. No firm data suggest that conjunctival epithelium migrates onto the corneal surface in the presence of intact limbal epithelium. Last, healing of the corneal epithelial wound is not complete until the newly regenerated epithelium has firmly anchored itself to the underlying connective tissue.
Permanent anchoring units are not formed until the wound defect is covered completely. Epithelial cells migrate rapidly and develop strong, permanent adhesions within 1 week when the basement membrane is regularly formed and released during the cell migration process.
Although transient attachments are regularly formed and released during the cell migration process, formation of normal adhesions takes 6 weeks, according to Dua et al. Tiny buds of corneal epithelium are present along the contact line between the normal corneal epithelium and the migrating conjunctival epithelium. These buds arise from the corneal epithelium, and normal corneal epithelium appears to replace the conjunctival epithelium by gradually pushing it toward the limbus.
The magnitude and extent of both the conjunctival and corneal regenerative responses to a corneal abrasion correlate with the size of the wound. Large erosions were reported to induce a pronounced response in the rate of epithelial cell migration and mitosis at the limbus.
Insults caused by chemical injuries, Stevens-Johnson syndrome, contact lens–induced keratopathy, and aniridia result in limbal damage. These insults cause delayed healing of the cornea, recurrent epithelial erosions, corneal vascularizations, and conjunctival epithelial ingrowth.
A long-standing clinical observation is that corneal abrasions and bacterial corneal infections do not occur in patients with an intact, healthy epithelium. Bacterial keratitis and abrasions develop in 1 of the following 3 types of patients:
The common feature among the 3 groups is a defect in the corneal epithelium to which the bacteria must adhere to start the infection. Mechanisms underlying the development of epithelial defects in the first 2 groups are self-evident. In the third group, contact lenses may lead to epithelial injury in any of the following ways:
Defects in the epithelium need not be full thickness. Overnight wearing of soft lenses, which do not provide sufficient oxygen transmissibility to prevent hypoxia, causes superficial desquamation of epithelium and increases the propensity for abrasions.
Corneal swelling induced by overnight wearing of contact lenses is the most important factor. The cornea normally swells 2-4% during sleep. With a contact lens, overnight swelling increases to an average of 15%, and gross stromal edema can be present on awakening. In some patients, induced corneal swelling can be sufficient to cause bullae; these can rupture, leading to epithelial defects.
Potential causes of corneal abrasion include the following:
In persons with trachoma, the constant corneal abrasion by lashes and inadequate tears can produce corneal erosions, ulceration, and scarring. These constitute the major pathway to blindness in trachoma.
Contact lens–induced epithelial defects or direct trauma during lens insertion or removal can cause corneal abrasions.
Abrasions occur more frequently with rigid lenses than with other lenses, possibly because of their small diameter and the sharp corneal defects they cause. Corneal abrasions due to soft lenses are observed most frequently with tight or extended-wear lenses. In these situations, acute epithelial hypoxia impairs attachment of the epithelium to the Bowman membrane.
The most common trauma is an inferior abrasion of the cornea caused by lens removal. Sometimes, the person's fingernail slices the contact lens and also the cornea. More often, the lens becomes slightly dehydrated at the end of the day because of insufficient blinking. The lens adheres to the cornea, removing the epithelium. This area may not heal well, especially if the epithelial cells are continually torn away. After the contact lens is removed, the patient may feel discomfort; however, no pain occurs when the lens is worn because it acts as a bandage. Patients who incompletely blink and those who work in a dry environment, read most of the day, or look at TV or computer screens should be warned about this complication.
A foreign body may become trapped under a contact lens and produce linear scratch marks on the cornea. The total irregularity of these wavy abrasions is the clue to this cause of injury.
A soft lens offers no protection against blunt trauma to the eye, but it does not pose any additional jeopardy in terms of eye trauma. For example, a soft lens does not adversely affect an eye injured by a fist or a ball. In industrial settings, a soft lens is not a substitute for safety glasses.
Rigid contact lenses may break or chip, causing punctate epithelial keratopathy.
Adverse corneal events, such as corneal abrasions, have been reported with techniques of overnight corneal reshaping with orthokeratology. Lang concluded that corneal compromise and poor compliance can cause adverse events with corneal reshaping. The need for ongoing patient education is important in both children and adults who wear contact lenses.
Corneal abrasions can occur in almost all sports. They most frequently occur in young people.
In places where soccer is played frequently, impact with the soccer ball causes approximately one third of all sports-related eye injuries. Contrary to previous ophthalmologic teaching that balls larger than 4 inches in diameter rarely cause eye injury, 8.6-inch soccer balls cause most soccer-related eye injuries, both serious (eg, hyphema, vitreous hemorrhage, retinal tear, chorioretinal rupture, angle recession) and minor (eg, corneal abrasions, contusions).
Approximately 1 in 10 college basketball players has an eye injury each year. Most basketball-related eye injuries are corneal abrasions caused by an opponent's finger or elbow striking the player's eye.
The incidence of severe eye injuries in wrestling is low. In a study at Michigan State University, 18.4% of wrestlers had eye injuries that were relatively mild (eg, lacerated eyebrows, corneal abrasions) and that left no permanent damage. The average college team with 25 players and 2600 athlete exposures should expect 1-2 eye injuries each season, with a significant injury every 9-10 seasons.
Although significant eye injuries are not a major risk in equestrian events other than polo, cross-country riders frequently have corneal abrasions from hitting tree branches overhanging the trail. Wearing spectacles with polycarbonate lenses provides adequate protection against this risk.
Although cross-country skiing causes fewer musculoskeletal injuries than alpine skiing, cross-country skiers are more likely than alpine skiers to have eye injuries, especially corneal abrasions from contact with tree twigs. Both cross-country and downhill skiers can have solar keratopathy (snow blindness) and injuries due to accidents with ski poles.
In patients undergoing eyelid surgery, corneal abrasion can result from sutures inadvertently placed through the tarsus or conjunctival surface. After sutures are placed, the lid should be everted to check that they are not exposed.
The globe and cornea should be protected during dissection and suture placement. A contact lens corneal protector or lid plate can be used.
General anesthesia is more likely to cause adverse systemic effects than local or ocular complications. Ocular problems that do occur are usually not serious and include corneal abrasion, chemical keratitis, hemorrhagic retinopathy, and retinal ischemia (rare).
The incidence of corneal abrasion from general anesthesia is as high as 44%. Simple precautions, such as instilling a bland ointment or taping the lids of the nonoperative eye closed, may prevent surface trauma produced by the surgical drape, anesthetic mask, or exposure. Decreased tear production under general anesthesia, proptosis, and a poor Bell phenomenon may worsen corneal exposure, requiring eyelid suturing in some susceptible patients.
Corneal abrasion is one of the complications of argon laser trabeculoplasty. Others include the following :
The plunger can cause corneal abrasion if the eye or tonometer moves during measurement. In addition, if the disinfectant solution (eg, alcohol) is not removed from the plunger, it can cause a local chemical keratitis where it touches the cornea.
The Schiøtz tonometer must be used in the supine position or in the sitting position with the head back far enough to be horizontal. An initial blink or avoidance reaction may occur as the patient sees the tonometer descending toward the eye.
Corneal abrasions are the most common eye injuries and are especially prevalent among people who wear contact lenses. Although corneal abrasions account for about 10% of eye-related emergency visits, the estimated incidence varies by population and depends on how they are defined and the activities involved in the mechanism of injury.
A sampling of diagnoses in the offices of family practice clinicians, internists, and pediatricians in the United States in 1985 found that eye complaints constituted 2% of all patient visits; traumatic conditions and foreign bodies were the reason for 8% of these visits.
Workplace eye injuries cause significant yet avoidable (with protective eyewear) morbidity and lost productivity. In the United States, 65,000 work-related eye injuries and illnesses that cause missed time from work occur each year.
A study of eye injuries in a major US automotive corporation found an annual incidence of 15 eye injuries per 1000 employees. Between July 1989 and June 1992, at 33 plants, a total of 1983 work-related eye injuries occurred, with 86.7% of cases being superficial foreign bodies and corneal abrasions. The eye injuries comprised 6% of total injuries. One third of eye injuries resulted in the inability of workers to resume normal duties for at least 1 day.
In another report, most patients with corneal foreign bodies did not take more than 1 day off work, and up to 30% sought treatment outside of working hours to avoid lost time from work.
The incidence of nonpenetrating injuries to the eye, which includes corneal abrasions, is 1.57% per year. Corneal abrasions are common, accounting for 12-13% of new cases seen in 2 different eye emergency units in the United Kingdom. They are also frequent presenting problems in general hospital emergency departments.
At a general hospital emergency department in the United Kingdom, 6% of all new cases were eye cases. Trauma accounted for 66% of these cases, or 4% of all cases; corneal abrasions or corneal or conjunctival foreign bodies accounted for 80% of eye trauma cases, or 3% of all cases.
Rates of corneal abrasion are equal in all races. More males than females are treated for corneal abrasions.
The incidence of corneal abrasion is higher among people of working age because younger people are more active than older people; however, people of all ages can have a corneal abrasion. Automotive workers between the ages of 20 and 29 years had the highest incidence of eye injuries.
The prognosis is usually excellent, with full recovery of vision if treatment is prompt; however, untreated corneal abrasions can lead to blinding corneal ulcers.
Some deep abrasions (eg, those involving the corneal stromal layer) in the central visual axis (ie, the central area of the cornea directly over the pupil) heal but leave a scar. In these instances, a permanent loss of visual acuity may occur.
Healing of minor abrasions is expected within 24-48 hours. Extensive or deep abrasions may require a week to heal.
Recurrent epithelial erosion sometimes occurs days to weeks after a healing of an abrasion caused by shearing injury (eg, from a fingernail or mascara brush). These erosions may be caused by damage to the basement membrane (to which the newly healed overlying cells do not adhere well) and subsequent slough due to mild hypoxia that occurs during sleep. Patients typically are awakened in the early morning by the same symptoms as those of a corneal abrasion. Ophthalmologic follow-up care and observation are indicated.
Significant morbidity is uncommon and mostly observed with infectious complications or allergies to medications used for treatment. Patients who are poorly nourished or who have compromised corneas are at particular risk. Close follow-up care is necessary, however, because of the ever-present danger of the abrasion progressing to an ulcer. Essentially all corneal ulcers begin with an abrasion.
Corneal abrasions associated with contact lenses can progress to pseudomonal or amebic keratitis and lead to further ocular damage (including perforation or corneal scarring) if not treated promptly. Abrasions involving exposure to vegetable matter are at a high risk for becoming fungal ulcers.
Minor injuries may place substantial economic burdens on otherwise healthy people because of time lost from work or school. Foreign body sensation and pain can result in loss of productivity.
A large study showed that 32% of automobile workers with eye injuries were unable to resume their normal duties for at least one day. Unfortunately, only 25% of workers in this study were wearing eye protection at the time of injury. In a retrospective review from Torino, Italy, ocular injuries, including corneal abrasions, were associated with significant morbidity.
Patients with a corneal abrasion typically complain of eye pain and an inability to open the eye because of foreign body sensation. The severity ranges from a mild foreign body sensation in cases of small abrasions to excruciating pain in large abrasions. Often, patients are too uncomfortable to work, drive, or read, and the pain frequently precludes sleep. Multiple attempts by the patient to "wash out" the eye can further disrupt the epithelial surface.
Other symptoms include photophobia, especially if secondary traumatic iritis is present, pain with extraocular movement, or blurred vision. Excessive tearing may occur. Conjunctival injection and eyelid swelling may be present. Most patients with concomitant atraumatic iritis can clearly distinguish between the aching discomfort from ciliary spasm and the foreign body sensation or scratchy discomfort from superficial corneal injury.
The patient's history typically includes trauma to the eye due to either a foreign object or a contact lens. Toxic chemicals (eg, ear drops) accidentally instilled into the eye can cause corneal abrasions. Symptoms typically begin instantly after trauma occurs and can last minutes to days, depending on the size of the abrasion.
If the source of injury is uncertain, the clinician should take a detailed history, with questions regarding any recent sports activities, makeup application, excessive rubbing of the eyes, use of contact lenses (including poorly fitting lenses and duration of use), and motor vehicle accidents. The occupation of the patient should be noted because certain people exposed to metals may have penetrating globe injuries.
Some patients have recurrent corneal abrasions days to years after the original abrasion heals. This is called recurrent corneal erosion syndrome. Symptoms include foreign body sensation, pain, and photophobia. Sharp, severe pain; photophobia; and lacrimation most commonly occur when these patients open their eyes in the morning upon awakening from sleep. Clinical signs are those of a corneal abrasion, but they may be minimal, especially if the patient is examined several hours after the onset of pain.
Unconscious patients (eg, patients in intensive care who are sedated and have lost their corneal reflexes) are prone to iatrogenic corneal abrasions, as their eyes remain open for some time and become dry. The nursing staff may inadvertently rub an eye while giving a face bath, abrading the cornea with a napkin or towel.
In some cases, a corneal abrasion is overlooked because of the insignificant nature of the causative agent or because of insignificant discomfort; however, the majority of patients with corneal abrasions have a definite and consistent clinical presentation. The corneal epithelium is richly innervated with sensory pain fibers from the trigeminal nerve, so most patients with a corneal abrasion are in obvious pain.
The clinical presentation is usually unilateral when the corneal abrasion is associated with trauma. It may be bilateral when it is associated with heritable or dystrophic disease.
The eyes should be opened with the lids retracted in order to get a full look at the cornea as well as conjunctiva. Extraocular movements should be assessed, and the pupillary reflex should be elicited. Occasionally, the patient may have a reactive miosis.
If there is any history or signs of globe injury with violation of ocular contents, a plastic or metal shield should be placed and an ophthalmologist should be called urgently.
Visual acuity should be assessed. If the abrasion affects the visual axis, there may be a deficit in acuity that should be apparent when compared to the uninjured eye.
If the examination is limited by pain, a topical anesthetic such as tetracaine or proparacaine may be used. The amount of anesthetic used should be minimal, as these agents have been shown to slow wound healing.
Visual inspection for foreign objects should be performed. Both upper and lower eyelids should be flipped in order to look for foreign bodies that may be lodged in the upper eyelid, causing injury with eye blinking. Also see Intraocular Foreign Body.
The cornea can become hazy if there is edema due to the abrasion. Conjunctival injection, usually located near the limbus, may also be present.
In advanced cases, findings can be more drastic, as follows:
Strongly consider use of a slit lamp examination with fluorescein to diagnose a corneal abrasion in ambulatory patients; without the magnification of the slit lamp, small abrasions can be missed.
If ocular penetration with a retained foreign body is suspected, such as in a high-velocity injury (eg, lawn mower, string trimmer, hammering metal), then an ocular CT scan, ocular MRI (if the object is nonmetallic), or both are indicated.
If a corneal ulcer (eg, microbial keratitis) is suspected (because of prolonged symptoms and/or risk factors such as contact lens wear), consider obtaining bacterial cultures before instilling antibiotics.
A topical anesthetic (ie, proparacaine, tetracaine) may facilitate the slit-lamp examination. Severe photophobia that causes blepharospasm may require instillation of a cycloplegic agent (ie, cyclopentolate [Cyclogyl], homatropine) 20-30 minutes prior to examination.
Perform fluorescein instillation and examination with blue light. Fluorescein can permanently stain soft contact lenses. Do not forget to remove such lenses before applying the stain.
Fluorescein is applied using a paper strip applicator that is gently placed over the inferior cul-de-sac of the eye and allowing saline or anesthetic solution to drop into the eye. Once the patient blinks, the dye is spread over the cornea.
Fluorescein stains basement membrane that has been exposed by damage to the corneal epithelium. This causes the abrasion to appear green using cobalt blue light or a Wood's lamp.(See the images below.) Corneal abrasions associated with contact lenses tend to be punctate or can be larger in a round shape.
This corneal abrasion appears as a yellow-green area when stained with fluorescein and viewed with a blue light.
Multiple linear, vertical abrasions suggest a foreign body under the upper eyelid. See the image below. Evert the eyelid to look for blepharoconjunctival foreign bodies.
Corneal foreign body with cobalt blue lighting showing abrasion.
If the patient has suffered penetrating ocular trauma, then leaking aqueous humor may be seen (Seidel sign). Examine the anterior chamber for evidence of iritis (cells and flare).
On histopathologic examination, intercellular and intracellular epithelial edema is associated with intraepithelial cysts, cellular debris, and intermittent pyknotic nuclei. Intraepithelial basement membrane formation may be present. Basement membrane under regenerating epithelium may appear thickened and multilaminar. Hemidesmosomes tend to be absent or form late in the course of epithelial healing.
Corneal abrasion and inflammation, paracentesis, intraocular infection, and uveal inflammation all cause a breakdown of the blood-aqueous barrier so that plasma proteins and inflammatory cells pour into the anterior chamber. As a result, inflamed aqueous humor has increased levels of serum proteins, including immunoglobulins and complement components C1-C7.
Corneal abrasions heal with time. Prophylactic topical antibiotics are given in patients with abrasions from contact lenses. Traditionally, topical antibiotics were used for prophylaxis even in noninfected corneal abrasions not related to contact lenses, but this practice has been called into question.
Patching the eye has been used to help relieve the pain associated with corneal abrasion, but research has not shown benefit from patching.[20, 21, 22] Patching should not be performed in patients at high risk of infection, such as those who wear contact lenses and those with trauma caused by vegetable matter, because of potential incubation of infecting organisms and promoting subsequent infectious keratitis.
Some ophthalmologists advocate the use of diclofenac (Voltaren) or ketorolac (Acular) drops with a disposable soft contact lens in addition to antibiotic drops.[23, 24, 25] This therapy may be an effective alternative to patching, as it allows the patient to maintain binocular vision during treatment and reduces inflammation.
Patients with all but the most minor abrasions usually require a strong oral narcotic analgesic initially. In addition, topical cycloplegics may be required to relieve pain and photophobia in patients with large abrasions until their healing is nearly complete.
Emergent ophthalmologic consultation is warranted for suspected retained intraocular foreign bodies. Urgent consultation is needed for suspected corneal ulcerations (microbial keratitis).
Determining the best treatment for a corneal abrasion depends on many factors, such as the severity of the injury and the degree of pain the patient is experiencing. But practitioners also must take into consideration the location of the abrasion, symptoms the patient may be exhibiting, and how the incident occurred. Was it simply a scratch or a shearing injury that tore the epithelium away from the underlying basement membrane? Was it caused by a plant-type material, a situation in which a later fungal infection may be possible?
The level of pain also figures into the treatment plan. Moreover, pain affects everyone differently, so pain management must be tailored to each individual. Two patients with essentially identical wounds or injuries may describe the pain level very differently. It is important to understand that pain is individual. When attempting to manage pain associated with corneal abrasion, the pain management approach must be based on the patient’s pain rather than the patient’s injury.
Any symptoms that a patient may display also helps decide the course of treatment. If the patient is experiencing significant sensitivity to light or excessive lacrimation, he or she should be treated differently from someone who has a small abrasion with minor symptoms. It also depends on the location of the injury. If it is central, the treatment plan should be more aggressive than if the injury is peripheral.
As the demand for refractive surgery grows, practitioners are more likely to see different types of corneal abrasions stemming from a surgical procedure.
Refractive surgery has reawakened the interest in treating corneal abrasions because many postrefractive surgery patients develop some mild degree of what would be considered an abrasion. Photorefractive keratectomy can cause a fairly substantial epithelial defect, which clearly goes beyond just an abrasion. In laser in situ keratomileusis, although there is not a massive area of open abrasion, there are peripheral areas of the cornea where the flap edge may exhibit a circumferential pattern of superficial punctate keratitis adjacent to the microkeratome cut. Many ophthalmologists have reacquainted themselves with this, in terms of refractive surgery offering unusual created abrasions that do not always completely heal.
While monitoring the cornea for signs that the tissue is healing, a bland lubricating ointment for 6-8 weeks to reduce the potential for recurrent erosion or a hypertonic ointment, depending on the appearance of the cornea, should be considered.
Hyperosmotic agent ointment (sodium chloride 5%) every night, in addition to a daily hypertonic drop, for 60 days should be considered.
If recurrent erosion can be prevented, the patient has been well served. Recurrent erosion can become a lifelong problem. Many patients with recurrent erosion eventually require laser procedures or corneal stromal micropuncture.
Unresolved corneal erosions present a challenge in terms of treatment.
Routine use of topical antibiotics for corneal abrasions remains controversial. Many emergency physicians have stopped using these agents for minor injuries, though others still treat corneal abrasions with broad-spectrum antibiotic ointments for lubrication and infection prophylaxis. Antibiotic use persists despite its unproved effectiveness and despite evidence that ointments may retard corneal epithelial healing.
Although use of prophylactic antibiotics after trauma or surgery is sometimes discouraged in general medicine, ophthalmologists use topical antibiotics for corneal abrasions because de-epithelialized cornea is more susceptible than intact cornea to infection, especially if the eye is patched. The injured cornea is vulnerable not only to pathogens contaminating any foreign body that produced the abrasion but also to potential pathogens present in the normal conjunctival flora.
Antibiotics should be continued until the patient is asymptomatic.
To the authors' knowledge, no randomized double-blind placebo-controlled trials have been conducted to evaluate the advantage of prophylactic antibiotics for noninfected corneal abrasions. Because the incidence of microbial keratitis in this setting is low, such a study is unlikely. The estimated annual incidence of ulcerative keratitis is 0.13-0.21% for people who wear extended-wear soft contact lenses and 0.02-0.04% for those using daily-wear soft contact lenses.
Fluoroquinolones (eg, ofloxacin) are probably the most common agents used for prophylaxis with corneal abrasions because of their broad-spectrum coverage and low toxicity and because of the low resistance of commonly acquired organisms to these drugs. In addition, fluoroquinolones have proven efficacy in the treatment of bacterial corneal ulcers. Prolonged and low-frequency dosing should be avoided to discourage the emergence of resistant organisms due to subinhibitory antibiotic concentrations on the ocular surface.
Ofloxacin has effectiveness similar to that of tobramycin for external ocular infection, fortified cefazolin and tobramycin for bacterial keratitis, and fortified gentamicin and cefuroxime for microbial keratitis. Trimethoprim also provides good broad-spectrum coverage and is an excellent prophylactic agent. A combination drop of polymyxin and trimethoprim is commercially available.
For large or dirty abrasions, many practitioners prescribe broad-spectrum antibiotic drops, such as trimethoprim/polymyxin B (Polytrim) or sulfacetamide sodium (Sulamyd, Bleph-10), which are inexpensive and least likely to cause complications. Alternatives are an aminoglycoside or a fluoroquinolone.
Abrasions due to contact lenses warrant antibiotic treatment because of their propensity to become infected corneal ulcers. Coverage for gram-negative organisms (especially Pseudomonas species) with agents such as gentamicin (Garamycin), tobramycin (Tobrex), norfloxacin (Chibroxin), or ciprofloxacin (Ciloxan) is recommended.
Antibiotic drops are more comfortable than ointments but must be administered every 2-3 hours. Antibiotic ointments (eg, bacitracin, polymyxin/bacitracin, erythromycin, ciprofloxacin) retain their antibacterial effect longer than drops and thus can be used less often (every 4-6 h), but they are more uncomfortable because they can cause visual blurring. Ointments are frequently used in children whose crying washes out the drops.
For topical use, the sterile powder is reconstituted by adding 20-50 mL of sterile water for injection or 0.9% sodium chloride solution for injection to a vial containing polymyxin 500,000 U. This mixture creates a solution with a polymyxin concentration of approximately 10,000-25,000 U/mL (10,000 U = 1 mg).
Avoid antibiotics containing neomycin (eg, Neosporin) because of the high incidence of allergy to neomycin in the general population. The use of prophylactic periocular injections or systemic administration of antibiotics after corneal abrasions is controversial.
The pain of corneal abrasions may be severe and should be treated with nonsteroidal anti-inflammatory drops and, if necessary, a soft bandage contact lens. Narcotic analgesia is occasionally required on a short-term basis. These are continued until the pain decreases to the point that it can be managed with over-the-counter analgesics.
Instillation of a long-acting cycloplegic agent can provide significant relief for patients with marked photophobia and blepharospasm. These agents relax any ciliary muscle spasm that may cause a deep, aching pain and photophobia. Cycloplegic agents are mydriatics; therefore, to prevent an episode of acute angle closure glaucoma, ensure that the patient does not have narrow-angle glaucoma.
Small abrasions can be managed on an outpatient basis. Ice compresses should be used for 24-48 hours to reduce edema. Warm compresses can be used thereafter.
Inform patients about the signs of wound infection, including increasing pain, erythema, edema, and purulent discharge. This helps in making the decision for early antibiotic intervention.
Patients must be informed about the signs and symptoms of complications, such as foreign body sensation, conjunctival injection, and decreased vision, so that treatment can be initiated promptly.
Flynn et al conducted meta-analysis of several studies of patching for corneal abrasions. Six groups had evaluated pain; 4 found no difference, whereas 2 favored not patching. Complication rates did not differ between use and no use of patches.
Flynn et al noted, "Eye patching was not found to improve healing rates or reduce pain in patients with corneal abrasions. Given the theoretical harm of loss of binocular vision and possible increased pain, the route of harmless nonintervention in treating corneal abrasions is recommended."
Although the use of slowly dissolving lenses made of porcine collagen is an excellent concept, this treatment is not widely used. A therapeutic lens that dissolves after 1-3 days is appealing, but most clinical indications require use of the lens for more than 3 days. An exception might be an uncomplicated corneal abrasion in which a collagen lens could be an alternative to a pressure dressing.
One study showed that, with common corneal abrasions, collagen lenses resulted in unexpected discomfort rather than decreased symptoms. In most applications, collagen lenses have failed to find acceptance because of their expense, induced discomfort, difficulty in handling, and lack of optical clarity. Furthermore, the lenses must be constantly replaced in applications in which more than 3 days of wear is required.
Another study demonstrated that collagen lenses were not helpful in healing persistent epithelial defects after penetrating keratoplasty.
Persons who work in high-risk occupations such as auto mechanics, metalworkers, or miners should wear protective eyewear. People who participate in contact sports such as hockey, lacrosse, or racquet sports such as squash or racquetball should always wear protective eyewear. Eye protection is also important for patients whose work or recreation increase the risk of corneal abrasion or ultraviolet light exposure (eg, farming, hiking through areas of tall foliage, skiing).
To prevent corneal abrasion in patients who are unconscious or who cannot voluntarily close their eyelids (eg, because of Bell palsy or other neuropathies), tape the eyelids closed.
Patients who wear contact lenses should make sure they fit properly and change them accordingly.
Close follow-up care of corneal abrasions is necessary because of the danger of the abrasion progressing to an ulcer. Essentially all corneal ulcers begin with an abrasion. Abrasions resulting from vegetable matter are at high risk for fungal ulcers. Abrasions resulting from contact lens wear should be monitored for Pseudomonas infection and amebic keratitis.
Patients with abrasions should receive follow-up care until healing is complete and the fluorescein stain is negative, to confirm that a corneal ulcer has not developed. However, minor abrasions should heal within 24-48 hours and do not require follow-up if the patient is completely asymptomatic at 48 hours. Reexamine large abrasions frequently until reepithelialization occurs and the potential for infection no longer exists.
Advise eye rest (ie, no reading or work that requires substantial eye movement that might interfere with reepithelialization). Advise patients to avoid bright light or to wear sunglasses for comfort if they have notable photophobia.
Patient with corneal abrasions that do not resolve with the use of routine prophylactic antibiotics must be evaluated for conditions that impede healing; examples are infection, neurotrophic keratopathy, and topical anesthetic abuse.
The goals of pharmacotherapy are to reduce morbidity and to prevent complications. Antibiotics may be used to prevent infection. Anticholinergics can reduce pain and photophobia in patients with large corneal abrasions. Topical anesthetics are used for analgesia to facilitate an adequate examination. Analgesics are indicated, as corneal abrasions can cause severe pain.
Clinical Context: Ofloxacin is a pyridine carboxylic acid derivative with broad-spectrum bactericidal effect. It inhibits bacterial growth by inhibiting DNA gyrase. It is indicated for superficial ocular infections of conjunctiva or cornea due to susceptible microorganisms.
Clinical Context: This combination is used for ocular infection of the cornea or conjunctiva caused by susceptible microorganisms. It is available as a solution (polymyxin/trimethoprim) and as an ointment (polymyxin/bacitracin).
Clinical Context: Ciprofloxacin has activity against Pseudomonas and Streptococcus species, methicillin-resistant Staphylococcus aureus (MRSA), S epidermidis, and most gram-negative organisms; it has no activity against anaerobes.
Clinical Context: Norfloxacin has activity against susceptible gram-negative and gram-positive bacteria. Antibiotics in this class inhibit bacterial DNA synthesis and thus growth by inhibiting DNA gyrase.
Clinical Context: Erythromycin is indicated for infections caused by susceptible strains of microorganisms and for prevention of corneal and conjunctival infections.
Clinical Context: This agent interferes with bacterial growth by inhibiting bacterial folic acid synthesis by competitively antagonizing para-aminobenzoic acid. It is available in solution, ointment, and lotion form.
Clinical Context: Tobramycin is an aminoglycoside that interferes with bacterial protein synthesis by binding to 30S and 50S ribosomal subunits, causing a defective bacterial cell membrane. It is available in solution, ointment, and lotion form.
Clinical Context: Gentamicin is an aminoglycoside antibiotic that covers gram-negative bacteria.
Therapy must be comprehensive and should cover all likely pathogens in the context of the clinical setting.
Clinical Context: Scopalamine blocks action of acetylcholine at parasympathetic sites in smooth muscle, producing pupillary dilation (mydriasis) and paralysis of accommodation (cycloplegia).
Clinical Context: Cyclopentolate is the anticholinergic drug of choice in the treatment of cornea abrasions. It prevents the muscle of ciliary body and sphincter muscle of the iris from responding to cholinergic stimulation, causing mydriasis and cycloplegia. It induces mydriasis in 30-60 min and cycloplegia in 25-75 min; effects last up to 24 h.
Clinical Context: Atropine acts at parasympathetic sites in smooth muscle to block response of sphincter muscle of iris and muscle of ciliary body to acetylcholine, causing mydriasis and cycloplegia. Concurrent phenylephrine (2.5% or 10% solution) may prevent the formation of synechiae by producing wide dilation of the pupil. Atropine induces mydriasis in 10-30 min and cycloplegia in 30-90 min; effects last up to 48 h.
These drugs are used in large abrasions. Specific agents such as cyclopentolate or atropine or even homatropine drops or ointments are useful adjuncts.
Clinical Context: Tetracaine is a local anesthetic that blocks initiation and conduction of nerve impulses by decreasing sodium permeability of the neuronal membrane, inhibiting depolarization and blocking impulse conduction. Onset of action is in 1 min; the anesthetic effect lasts up to 15-20 min. This agent stings considerably on application. It is available as a solution and an ointment.
Clinical Context: Proparacaine is the least irritating of the topical anesthetics. It prevents initiation and transmission of impulses at the nerve cell membrane by stabilizing it and decreasing ion permeability. Onset of action is in 20 sec; anesthetic effect lasts up to 10-15 min.
Topical anesthetics are used for analgesia to facilitate an adequate examination. These agents should never be prescribed for home use because they can cause secondary keratitis, compromise healing of the epithelial wound, and block protective corneal reflexes and sensation.
Clinical Context: These nonsteroidal anti-inflammatory drugs inhibit prostaglandin synthesis by decreasing cyclooxygenase activity, decreasing formation of prostaglandin precursors.
Clinical Context: These nonsteroidal anti-inflammatory drugs inhibit prostaglandin synthesis by decreasing cyclooxygenase activity, decreasing formation of prostaglandin precursors.
Clinical Context: These drug combinations are used for relief of moderate to severe pain.
Clinical Context: These drug combinations are used for relief of moderate to severe pain.
Some ophthalmologists advocate the use of diclofenac (Voltaren) or ketorolac (Acular) drops with a disposable soft contact lens in addition to antibiotic drops. This therapy may be an effective alternative to patching, as it allows the patient to maintain binocular vision during treatment and reduces inflammation. Patients with all but the most minor abrasions usually require a strong oral narcotic analgesic.