Clinical and Health Affairs
Red Eyes, Red Flags
Answers to Frequently Asked Questions about the Eye
By Steven Grosser, M.D.
Abstract
Although primary care physicians often encounter ocular diseases, they sometimes feel unsure about how to treat them or when to refer patients for more specialized care. This article describes several common eye problems as well as several uncommon but potentially serious ocular presentations of systemic disease and how they should be treated in a primary care setting.
Many patients appropriately present first to their primary care doctor or to urgent care with red eyes or blurry vision, or after experiencing trauma to the eye. Unfortunately, most medical schools and residency programs in the United States do not adequately train these physicians in ocular diseases or eye examination techniques. Even when they have such knowledge, these providers rarely have access to the tools they need to evaluate ocular complaints—a slit lamp, tonometer (to check eye pressure), or indirect ophthalmoscope. Therefore, they may feel uncomfortable triaging or treating patients who present with eye complaints. This article answers questions about several common and serious ocular conditions that are often seen in primary care practices.
When is a red eye more serious than benign conjunctivitis?
Three symptoms may indicate a red eye is potentially serious: decreasing vision, sensitivity to light (photophobia), or more-than-mild pain. These often are signs of serious diseases such as closed-angle glaucoma, endophthalmitis, iritis, infectious keratitis (corneal infection), and orbital disease such as cellulitis. As a general rule, red eye caused by uncomplicated viral conjuctivitis, blepharitis, and allergies may be bothersome, but it is not typically associated with these symptoms.
Several examination findings also could indicate a more serious problem. The presence of a hypopyon likely indicates severe inflammation, possibly endophthalmitis. A sluggishly dilated pupil suggests high eye pressure possibly from angle-closure glaucoma. Proptosis or diplopia may indicate orbital disease.
If I encounter a patient with a red eye, what clues should I look for in their medical history that might indicate a potentially serious problem?
A number of conditions and events can place people at higher risk for serious eye disease. When taking an ocular history, be sure to note any previous surgery. If a patient recently had eye surgery, a red eye requires immediate consultation.
Patients who have a history of corneal transplant or glaucoma surgery have a lifetime risk of developing serious complications. For example, a patient who has had a corneal transplant and presents with a red eye may be experiencing rejection, placing the health of the graft at risk. Patients who have had trabeculectomy, a glaucoma surgery that creates an artificial pathway that allows fluid to drain from the eye, are at increased lifetime risk of endophthalmitis. This surgery is often performed with a fibrinolytic agent called mitomycin, which may leave a thin bleb of conjunctiva under the upper lid, through which bacteria may migrate into the eye. Endophthalmitis in this setting has a particularly poor prognosis.1
Also, a history of contact lens wear, especially overnight wear, increases the risk of a bacterial corneal ulcer.2 In addition, a history of herpes simplex keratitis and iritis increases the chance that the red eye is a recurrence of such an infection.
Can I use a steroid eye drop to treat a red eye if its cause has not yet been determined?
Several ocular conditions will worsen if treated with a steroid such as Pred Forte (prednisolone) or steroid-antibiotic combination such as Tobradex (tobramycin, dexamethasone) and Maxitrol (neomycin and polymyxin B sulfates and dexamethasone ophthalmic suspension). The most common condition inappropriately treated with such medications is corneal infection. Herpes simplex virus and fungal or bacterial infections in particular can be more challenging to treat after topical steroids have been started because the steroid reduces the immune response and potentiates replication of the organism. Treatment of early endophthalmitis or glaucoma with steroids can be particularly harmful because it may mask symptoms and delay diagnosis. Vision loss will almost certainly occur if the correct diagnosis is not promptly made.
If you cannot perform a slit-lamp examination to rule out corneal infection and other diseases, refrain from using topical steroids and consult with or arrange for a timely evaluation by an ophthalmologist.
My patient is having episodes of vision loss. What do I need to consider?
A worrisome history is vision loss described as a graying or blackening of the entire visual field or a portion of it that lasts seconds to minutes. The patient’s history will help clarify whether this is amaurosis fugax, which is vision loss in 1 eye, or homonymous vision loss, which occurs in the same visual field in both eyes.
This type of vision loss often indicates a serious systemic disease such as ischemic emboli from cardiac, carotid, or vertebrobasilar sources. Prompt evaluation is required in all cases. If the patient is 55 years of age or older, consider whether this may be an ocular presentation of temporal arteritis, a condition that may cause blindness as a result of ischemic optic neuropathy. Ophthalmic presentations of temporal arteritis may occur without the usual systemic symptoms—headache, jaw claudication, arthralgias, fever, weight loss, or scalp tenderness.3,4 An elevated ESR, platelet count, and C-reactive protein level can aid in the diagnosis. According to the ophthalmic literature, C-reactive protein is the single most sensitive test for temporal arteritis, more so than ESR.5 Vision loss in a patient with suspected temporal arteritis is an ophthalmic emergency because of impending ischemic optic neuropathy. Such patients require immediate administration of high-dose steroids and referral for a timely temporal artery biopsy.
My patient says she has double vision. How serious is this?
The first thing to do is clarify whether the diplopia is monocular or binocular. If the diplopia is still present with 1 eye covered, it is considered monocular. Monocular diplopia is often described as seeing a ghost or shadow image of an object or light at a distance. In all likelihood, this is not caused by serious systemic disease, although it can be an occasional response to fluctuating blood glucose. Monocular diplopia indicates a problem with the refractive system: glasses, tear film, cornea, or intraocular lens.
On the other hand, if closure of either eye eliminates the symptom, the patient has binocular diplopia. Binocular diplopia indicates ocular misalignment and suggests potentially serious orbital or neurological disease. Orbital and brain imaging often are required to make a diagnosis. When diplopia occurs with ptosis (a droopy lid) and a dilated pupil on the same side, there is possibility of a third nerve palsy. A new third nerve palsy is a neurologic emergency, possibly indicating enlargement of a cerebral aneurysm. Immediate imaging is required. Magnetic resonance angiography or CT angiography can rule out an aneurysm large enough to cause compression of the third cranial nerve.
My patient who is having cataract surgery is taking Flomax. Should the medication be stopped?
Alpha-1A receptor antagonists, commonly used to treat urinary retention from prostate hypertrophy, can cause intraocular floppy iris syndrome (IFIS). IFIS is a concern for ophthalmologists because it may pose increased risk during cataract surgery.6
Floppy iris is most frequently associated with Flomax (tamsulosin), but it can be caused by any medication in its class. (Saw palmetto, a natural remedy used to treat benign prostatic hyperplasia, is only rarely associated with IFIS.)
During surgery, a dilated iris will normally remain stable, but a floppy iris will constrict and billow like a sail in the wind with the circulation of fluid within the eye. The cause is thought to be inhibition of adrenergic dilation and muscle tone of the iris. Interestingly, there is no evidence that stopping the alpha blocker prior to surgery will reverse the condition.7 Therefore, most ophthalmologists elect not to alter therapy, avoiding the risk of acute urinary retention. Medications and devices can stabilize the iris during cataract surgery, and evidence suggests that if surgeons are prepared to encounter a floppy iris, complication rates are low.8 Because of the added challenge and potential risk associated with surgery in this situation, many cataract surgeons would opt to remove a symptomatic cataract prior to starting an alpha-1 antagonist.6
My patient is complaining of floaters. What’s the next step?
Floaters are variably described as small dots, spider webs, amoeba, or ghost-like images. The common denominator is that they “float,” meaning their spatial relationship to fixation varies as the eye moves. Floaters are caused by small opacities in the vitreous, which in bright conditions cast visible shadows on the retina.
Floaters are extremely common. However, the sudden appearance of new floaters indicates a potentially serious ocular event, most often a separation of the vitreous from the retina. A vitreous separation is often associated with photopsias (brief flashes of light in the periphery). In 5% to 15% of cases, an acute vitreous separation will cause a retinal tear, which if not treated may lead to a retinal detachment.9 Therefore, a timely ophthalmologic examination is warranted. Risk factors for retinal tears and detachments include nearsightedness, previous cataract surgery, trauma, and a history of retinal detachment in the other eye.10 Another cause of floaters that is serious is hemorrhage into the vitreous, for example from neovascularization in a patient with diabetic retinopathy. In rare cases, floaters that worsen can indicate an intraocular neoplasm such as lymphoma.
Sometimes small blind spots may be mistaken for floaters but are instead caused by retinal, optic nerve, or cerebral disease. In those cases, the blind spot does not move in relation to fixation.
My patient was hit in the eye. What should I do to assess for ocular injury?
The most important thing to look for when you encounter a patient with direct globe trauma is rupture of the eye. Urgent consultation with an eye care provider is recommended in this situation. However, if no eye care provider is immediately available, do a careful exam, checking the patient’s vision and closely inspecting the anterior segment of the eye. Vision loss, a blurry view to the iris, hyphema, an irregularly shaped pupil, and an impaired view to the retina when using an ophthalmoscope are all potential signs of serious injury. A subconjuctival hemorrhage on rare occasion can be the site of an entry wound, especially if there is a history of injury with a small projectile. If tonometry is available, hypotony is indicative of globe rupture.
Although any injury is cause for concern, some are more serious than others. For example, paint balls, BB guns, Airsoft guns, and bungee cords are often associated with serious intraocular injury. Patients whose unprotected eyes are injured by sharp projectiles such as those produced while drilling, hammering, or sawing may harbor an occult intraocular foreign body.
Eyes that have undergone LASIK, a procedure that involves cutting a thin corneal flap, deserve special consideration. An injury that would normally cause a corneal abrasion, such as a scrape from a tree branch, could dislocate the corneal flap, even years after surgery. This may appear simply as an area of corneal staining; but a careful slit-lamp examination is necessary to judge the depth of the injury. This is not an issue for patients who have had PRK, the corneal refractive procedure that does not involve cutting a flap. Trauma to the eye can place it at higher risk for glaucoma, retinal detachment, and other conditions even decades afterwards, so regular eye examinations are recommended for patients who have had an eye injury.
I’m writing a prescription for Viagra (sildenafil), and my patient asks about the possibility of permanent vision loss. How should I advise him?
A very rare association between erectile enhancement medications and anterior ischemic optic neuropathy has been described in the medical literature.11 The risk is nearly 1 in a million, but the consequence is often severe vision loss. The primary risk factor is believed to be a structurally crowded optic nerve, which occurs congenitally in a minority of people. For a patient concerned about the risk of vision loss, an ophthalmologic examination could confirm the presence of this congenital variant.
My patient isn’t following my good advice. Could it signify an eye problem?
Especially in the elderly, vision loss commonly contributes to depression and cognitive decline, poor balance and falls, as well as poor compliance with physician recommendations for medications or insulin dosing. Patients with these problems should have a yearly eye examination in order to prevent them from worsening and be encouraged to take precautions when their safety might be an issue. MM
Steven Grosser is an ophthalmologist at West Metro Ophthalmology in Golden Valley.
References
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