The decision as to whether a patient requires an immediate examination is important and it rests heavily on the shoulders of the ophthalmic assistant. Without previous medical training and amid the noisy clatter of the outer office or clinic, the assistant must be prepared to screen the incoming calls and decide in a period of 30 seconds or less which patient has a complaint or symptom that can be an ocular emergency.
With industrial or traumatic injuries, this decision can be discharged rapidly and with authority. Obviously, a patient who has suffered a flash burn of the cornea or a laceration of the eyelid cannot be kept waiting until there is an open appointment. On the other hand, each patient who calls to make an appointment has some ocular problem that is causing some real or functional derangement of vision. The high myope with lost glasses is just as incapacitated as is the individual who has suffered an episode of acute chorioretinitis. Both patients cannot see. The only difference between the two situations is that the myope has a static problem that can be solved the moment spectacles or contact lenses are received, whereas chorioretinitis is a progressive problem that must be stopped before serious damage has occurred.
When patients are screened, a system of priority must be established that can be exercised rapidly and efficiently. In this section, instead of merely cataloging the diseases that constitute an immediate threat to an eye, we discuss their symptoms and signs and attempt to assemble them into a meaningful classification. As with all classifications, the purpose is to provide an orderly way of thinking about a particular symptom or disease. It is impossible to cover all situations. Professionals cannot blame patients for not presenting “textbook” problems, but with some flexibility they can realize that exceptions will occur. We favor, in cases of doubt, erring on the side of caution and providing an appointment rather than letting the single “functional patient” with a flashing-lights symptom silently extend a retinal hole or tears to a full retinal detachment while patiently awaiting that cherished appointment 3 months hence.
True emergencies (therapy should be instituted within the hour)
Sudden loss of vision
Central retinal artery occlusion ( Figs. 22.1–22.3 )
Chemical injuries of the eye
Penetrating injuries of the eye ( Fig. 22.4 )
Urgent situations (patients should be seen the same day)
Acute narrow-angle glaucoma ( Fig. 22.5 )
Corneal ulcer ( Fig. 22.6 )
Corneal foreign body
Acute iritis ( Figs. 22.7 and 22.8 )
Hyphema (hemorrhage in the eye)
Blow-out fracture of the orbit
Semiurgent situations (patients should be seen within days)
Protrusion of an eye
Previously undiagnosed glaucoma
Old retinal detachment.
Urgent case: to be seen within the hour
Sudden loss of vision in one eye without pain
This symptom in an adult usually means a central retinal artery occlusion, a central retinal vein occlusion, a vitreous hemorrhage, or a massive retinal detachment. Retrobulbar neuritis causes a loss of central vision, but side vision (peripheral vision) usually remains intact. All these conditions require immediate examination and early therapy and therefore belong to the category of the urgent situation.
Central retinal artery occlusion is the most urgent in terms of time. If this artery remains occluded for 2 to 4 hours or more, the involved eye most likely will go blind. If sight is to be salvaged, the ophthalmologist must attempt to dislodge the occlusion in the central retinal artery to a more peripheral branch. Only minutes should be allowed to elapse between the initial event and the onset of therapy. In some cases, the ophthalmologist may institute treatment up to 48 hours after the onset of symptoms even though the prognosis for any vision restoration is very poor. Evaluation with the stroke team is necessary for these patients.
The other conditions that cause sudden vision loss also require early treatment, but this can be measured in hours rather than minutes. On the basis of symptoms, the patient with a central retinal artery occlusion cannot be differentiated from the patient with a vitreous hemorrhage or retinal vein thrombosis. Therefore any patient who complains of sudden loss of vision in one eye is an emergency case and requires fire-alarm respect.
It is true that the ophthalmic assistant may experience many false-positive cases and believe that he or she is gaining a reputation as an alarmist. A patient may state that vision in one eye is lost, whereas examination reveals that vision was merely blurred. However, one good result in a potentially serious case is worth the feeling of chagrin in finding 10 false-positive cases.
Some patients may lose sight in one eye insidiously and make this appalling discovery quite suddenly. This can occur in glaucoma patients who quietly lose sight in one eye and then casually rub their good eye, only to discover that they are momentarily blind. Therefore the discovery of blindness in one eye may be sudden but the inciting sequence of events leading to this state can be chronic. This type of case must be added to the list of false-positive ocular emergencies.
Options for therapy by the ophthalmologists for central retinal artery occlusion include: (1) increasing the blood oxygen content to the eye by using vasodilators, pentoxyphyline, inhalation of carbogen, hyperbaric oxygen, or sublingual isosorbide dinitrate; (2) reducing intraocular pressure and thereby increasing the retinal artery perfusion or helping dislodge the embolus by ocular massage, anterior chamber paracentesis, intravenous acetazolamide, intravenous mannitol, or topical antiglaucoma medications; (3) reducing retinal edema by intravenous methylprednisolone; (4) lysing or dislodging the clot by Nd:YAG laser embolectomy; and (5) assisting in thrombolysis of the embolus by intraarterial or intravenous thrombolysis.
The ophthalmic assistant should always be prepared for a central retinal artery occlusion by consulting, in advance of the need, with the ophthalmologist to determine which instruments, medications, inhalants, and supplies the ophthalmologist wishes to have readily available to institute rapid therapy in the event of a patient presenting with a central retinal artery occlusion ( Fig. 22.9 ).
Chemical injuries to the eye require prompt attention. As soon as the patient arrives at the office, the ophthalmic assistant should institute initial therapy, which consists of irrigating the eyes with water or saline for approximately 30 minutes. This is done to wash away any chemicals that still have the potential to cause ocular damage. The visual prognosis as a result of chemical injuries must initially be guarded because the full effects of the injury may not be appreciated for several weeks.
Sudden loss of vision in both eyes is a rare event and does not require any degree of sophistication to realize that it also constitutes an ocular emergency.
A significant and acute loss of vision can result from a central retinal vein occlusion (CRVO) ( Fig. 22.10 ) or a branch retinal vein occlusion (BRVO) ( Fig. 22.11 ). In CRVO, the hemorrhages are located primarily at the posterior pole but may be seen throughout the fundus ( Fig. 22.12 ). In BRVO, the hemorrhages are located in the distribution of the occluded vein (see Fig. 22.12 ).
The intraocular pressure may be elevated, inasmuch as patients with vein occlusions often have a higher incidence of glaucoma. Fluorescein angiography may be performed to determine the extent of retinal ischemia or macular edema. Panretinal laser photocoagulation is indicated if the retina shows significant ischemic changes. This prevents the neovascularization of the anterior chamber angle, which can lead to glaucoma. In BRVO, focal laser photocoagulation may improve visual acuity and may be indicated for chronic macular edema. If neovascularization does occur, then focal laser photocoagulation may resolve the neovascular tufts and prevent vitreous hemorrhage. These patients do not need to be seen within hours as there is no urgent treatment that can be done. However, the diagnosis is important and a referral to a family physician for workup of hypertension, diabetes, and hypercoagulable state (in young patients) is vital for the patients to prevent any further complications.
Urgent case: to be seen the same day
Painful red eye
Painful red eye, with or without a concomitant decrease in visual acuity, is a complex symptom that deserves immediate attention. Four conditions usually are responsible for a painful red eye:
Acute glaucoma (a congested, tense eyeball caused by sudden blockage of the aqueous outflow)
Acute conjunctivitis (inflammation of the outer eye) ( Fig. 22.13 )