Corneal Abrasions and Ulcers PDF

Corneal abrasions are areas in which the cornea is devoid of its surface epithelium. They are usually the immediate consequence of mild to moderate ocular trauma. There is no infection or inflammation present and the cornea remains clear. Corneal abrasions are very common and can usually be treated...

Corneal abrasions are areas in which the cornea is devoid of its surface epithelium. They are usually the immediate consequence of mild to moderate ocular trauma. There is no infection or inflammation present and the cornea remains clear. Corneal abrasions are very common and can usually be treated by a general practitioner. A corneal ulcer is an area of corneal epithelium loss accompanied by epithelial and/or stromal inflammation and infection. They occur either after ocular trauma or in patients prone to corneal infections, and are characterised by loss of corneal clarity. In contrast to abrasions, corneal ulcers are potentially sight threatening emergencies which require immediate referral to an ophthalmologist. Included in this document History Examination Common ulcer syndromes Differential diagnosis Treatment Follow up Key points History Patients with corneal abrasions and ulcers are usually miserable with painful, red, photophobic eyes, a foreign body sensation and decreased vision. Although these symptoms are not that specific, careful directed questioning can be very useful in establishing what exactly is wrong with the eye and managing the problem. How long has the problem been present? Corneal abrasions typically heal within 24-48 hours. Patients with persistent or worsening symptoms are more likely to have an ulcer. Was there trauma? Patients with abrasions usually give a clear history of ocular trauma, most commonly sustained during play or sports. As in every eye injury it is important to ascertain exactly what happened. Make sure there is no possibility that there is a penetrating injury (sharp objects, high speed tools, hammering metal on metal etc). Patients with corneal ulcers may or may not have a history of eye trauma. Where infection follows trauma there is often a delay of several days before the infection becomes symptomatic so it is important to specifically ask whether trauma has occurred. Are there any risks for ulceration and infection? Certain patients are more likely to develop ulcers or develop infection following an abrasion. Ulcers are more common in patients who are immuno-compromised, have very dry eyes, blepharitis, or wear contact lenses. Contact lens wearers are more prone to corneal ulcers for several reasons. They often sustain small corneal abrasions when inserting and removing their lenses, and the lenses, storage cases and solutions are prone to bacterial, and occasionally fungal and amoebic, infection. Abrasions caused by organic materials (vegetable matter, animals and humans) are more likely to become infected and it is important to consider whether the incident causing the injury may have deposited foreign material in the cornea or under the eyelid. Has the patient had a corneal ulcer before? The commonest cause of recurrent corneal ulceration is herpes simplex, so always ask about this disease. Examination Examination is the key to distinguishing whether a patient has a corneal abrasion or corneal ulcer. That said, examining patients with corneal lesions is often very difficult as they are usually in pain, photophobic and have a very watery eye. If examination is difficult, instil a topical anaesthetic such as amethocaine or lignocaine. The anaesthetic agent must be NON-PRESERVED to avoid compromising later microbiology specimens. Dramatic relief of symptoms following the instillation of a topical anaesthetic also helps confirm the patient has a problem on the surface of the eye (as apposed to deeper inflammation, such as iritis) but doesn’t distinguish abrasions from ulcers. Vision and pinhole vision Test the vision and pinhole vision. If either are reduced, instil a topical anaesthesia, wait a few minutes and test again. Patients with abrasions have near normal vision as long as they are not in severe pain or have a very watery eye. The vision is usually reduced (and often profoundly so) when an ulcer is present. The eye An eye with an abrasion is normally mildly hyperaemic and watery, eyes with ulcers are more deeply injected and a mucopurulent discharge is common. Evert the eyelid and check for a retained foreign body. The pupil should be round and reactive, it is usually small due to pupillary spasm. The cornea Look carefully at the cornea with a bright light. Magnification can be a great help, so use your ophthalmoscope or a loupe magnifier if possible. Both corneal abrasions and ulcers will ‘stain’ with fluorescein but the presence of staining confirms at least an epithelial defect. The most important fact to ascertain is whether the cornea is clear or cloudy. A patient with an abrasion still has a bright and clear cornea (Fig.1). Dense cloudiness is easy to spot but in some patients the change is more subtle (Fig. 2). The easiest technique is to compare the cornea to its fellow, looking carefully at the iris details which should be equally clear in both eyes. Corneal clouding is a very sinister sign; it suggests stromal swelling or infiltration, both signs of infection. Look carefully for a hypopyon (pronounced high-pope-e-on). Instil fluorescein into the conjunctival sac. When an epithelial defect is present the fluorescein stained tears fill the hollow area. Because the thickness of the tears at that point is greater, the defect lights up or ‘stains’. Later, due to lack of the epithelial barrier, fluorescein leaks into the corneal stoma and the stroma ‘stains’. Fig. 1. Corneal abrasion. This Fig. 2. Corneal ulcer. The corneal patient has sustained moderate stroma is very cloudy. A hypopyon is ocular trauma. A central corneal present. abrasion is highlighted with fluorescein. The patient also has a small hyphema, seen as a dark ring of blood in the peripheral anterior chamber, from 4-7 o'clock. (Courtesy Dr D. Peart) Common ulcer syndromes There are four types of corneal ulcer syndromes that deserve special mention due to their relatively stereotyped presentation. Recurrent corneal erosion syndrome Recurrent erosion syndrome is a common condition. Some patients have an underlying corneal problem but more commonly they develop the problem a few days after sustaining a corneal abrasion. Patients classically describe going to bed with no eye problem, only to awaken later in severe pain. The pain usually strikes at the onset of REM sleep or on awakening in the morning. During sleep a relatively weak adhesion develops between the eyelid and corneal epithelium. In recurrent erosion syndrome this force can exceed that holding the epithelium to the underlying corneal stroma so that when the eye or eyelid moves the epithelium is literally torn off. The patient awakes in severe pain, and with photophobia and decreased vision. Fortunately the corneal epithelium normally heals without scarring in about 12 to 24 hours depending on the extent of loss. Marginal ulcers Marginal ulcers are very common and some patients suffer from them over and over again. Most recurrent cases occur in patients with staphylococcal blepharitis when an immune reaction to staphylococcal endotoxins occurs in the peripheral cornea. The ulcers typically occur at the point where the eyelids cross the eye, i.e. at the 2, 5, 7 and 10 o’clock positions where the endotoxins are most likely to diffuse into the cornea. Marginal ulcers usually have a classical appearance (Fig. 3). They start as an immune complex reaction in the mid stroma and subsequently ulcerate anteriorly. Marginal ulcers lie near the limbus but are separated from it by a thin area of clear cornea. Often the ulcer has a ‘banana’ shape as the area of inflammation follows the curvature of the limbus. The area of stromal infiltrate is usually bigger than the area of epithelial loss; indeed there is often no epithelial loss initially and so these ulcers may not stain with fluorescein. Herpetic keratitis Some patients with herpes keratitis develop a classical dendritic ulcer (Fig. 4) but any epithelial defect in a patient with previous ocular simplex has recurrence until proven otherwise. The eye is usually mildly injected and watery and the vision is usually mildly reduced. Some patients develop deeper inflammation, known as disciform stroma keratitis (Fig. 2). In these patients the cornea becomes cloudy and the vision is markedly decreased. Infectious keratitis In healthy adults infectious keratitis usually follows a corneal injury. Injuries caused by vegetable matter (eg branches) and animals are very likely to become infected. Ulcers are also more common in contact lens wearers and the immuno- compromised. Occasionally they arise as a complication of conjunctivitis. The cardinal signs of keratitis are corneal opacification (Fig. 5) and an epithelial defect. The presence of a hypopyon (Fig. 5) is a sinister sign. Fig. 3. Marginal ulcer. Marginal ulcers are Fig. 4. Dendritic ulcer. This is Fig. 5. Infectious keratitis. The typically white elongated lesions located a a classical dendritic ulcer; a cornea is hazy, obscuring the view millimetre from the limbus. Most are wandering line with bud-like of the iris and pupil. There is a located between the eyelids. branches. hypopyon and within the central epithelial defect, a coagulum of dead microbes and corneal cells has collected. Differential diagnosis The most common mimics of an abrasion and ulcer are a foreign body, conjunctivitis and iritis. None of these have a corneal defect. Look carefully for a foreign body on the cornea or under the eyelids. Conjunctivitis is usually bilateral. Treatment Simple abrasions The treatment of an abrasion depends on the history, extent of epithelial loss, age of the patient and the degree of discomfort. Patients who have an abrasion which was caused by a clean object and who have minimal pain can be simply treated with a single instillation of an ophthalmic ointment such as sulphacetamide or chloramphenicol. Where there is a possibility of infection the antibiotic ointment should be instilled four times a day for three days. Patients in more severe pain should have an ointment instilled and the eye firmly padded. Padding may in fact delay re-epithelialisation but can make the patient much more comfortable. Children don't tolerate padding and adults must have a firm double pad if it is to be effective. Cycloplegia with a single drop of a short acting agent such as cyclopentolate can also relieve pain. Avoid longer acting agents such as homatropine and atropine. Don’t forget simple analgesia and a hypnosedative. Contact lens wearers should leave out their lenses until the eye feels back to normal. NEVER issue or prescribe a topical anaesthetic agent, which will simply mask symptoms and delay healing. Recurrent erosion syndrome Immediate treatment is as per an abrasion. Long term the patients need reassurance that the situation usually resolves, together with a preventative strategy. A soft ointment such as paraffin (Lacrilube) should be instilled at night for one week after the first attack or for one month after the latest episode if the problem is recurrent. The patient should be encouraged (if they can remember) to slowly rotate the eye before opening the lids in the morning. Marginal ulcers Marginal ulcers are treated with a combination of steroids and antibiotics, usually given as a combination agent such as Maxitrol (dexamethasone, neomycin and polymycin). Most ophthalmologists will allow GPs to treat patients with recurrent marginal ulcers with steroids following a telephone call. The treatment is given qid. for 10 days. Patients with recurrent marginal ulcers and blepharitis should be treated for blepharitis. Dendritic ulcers Patients with a dendritic ulcer need semi-urgent ophthalmic review. If the problem is recurrent and the vision is good, most ophthalmologists are happy for you to prescribe 3% Zovirax ointment 5 times daily as long as they see the patient within the next few days. Infectious keratitis All cases of infectious keratitis should be immediately referred to an ophthalmologist. NO ANTIBIOTIC OR ANAESTHETIC agents should be instilled as this will make it much more difficult to culture the organism following a corneal scraping. Contact lens wearers should pass by their home on the way to the ophthalmologist, to pick up their contacts, and lens cases and solutions. These will all be cultured. Follow up Sensible patients with minor abrasions do not need follow up. They should reattend only if their symptoms worsen or fail to resolve. Ask them to see you again if their eye becomes increasingly red or painful, if the vision becomes blurred or any corneal opacity develops. Review patients with major abrasions or a sinister history after 24 hours and then according to their symptoms and signs. It is very common for the eye to remain a little irritable for several days after an epithelial  abrasion, but it should feel better each day. Patients with large abrasions should be reviewed the following day because it may take 48 hours for such defects to heal, and it is harder for patients to detect any early complications such as the onset of infection. Injuries involving plant and animal matter should be followed more closely. Key points Corneal abrasions are areas of epithelial loss and are not associated with clouding of the cornea. They usually heal quickly with minimal treatment and can be treated by a GP. Corneal ulcers result in loss of corneal transparency and are potentially sight threatening. Most require ophthalmic review. © GP Eyes - Dr Malcolm McKellar 2011