Emergency treatment

There is no definitive treatment of CRAO. Both medical and surgical approaches are disappointing.1719 The standard therapy includes ocular massage, anterior chamber paracentesis, topical medications to lower the intraocular pressure, intravenous or oral acetazolamide, and inhalation of a mixture of 95% oxygen and 5% carbon dioxide (carbogen). The efficacy of these treatments has not been proven.20

Nevertheless, in cases that have been blind for less than 24 hours, gratifying recovery of vision has been reported in eyes treated six, eight, and twelve hours after the event.21 For this reason, take the following emergency steps.

1 Place the patient flat and give firm ocular massage to lower intraocular pressure and help dislodge the embolus into the peripheral retinal circulation.

2 Have the patient rebreathe into a paper bag to build up carbon dioxide.

3 Give a bolus of intravenous acetazolamide 500 mg to lower intraocular pressure.

4 Refer the patient immediately to an ophthalmologist for an emergency anterior paracentesis. After surgery consider intravenous heparin therapy and, if there is a suspicion of vasospasm, give an intravenous bolus of methylprednisolone.

Other medical therapies proposed include sublingual nitroglycerine, oral warfarin sodium (coumadin), calcium channel blocking agents, vasodilators, antiplatelet agents, intravenous heparin, urokinase or tissue plasminogen activator (tPA), and intra-arterial urokinase or tPA. Schmidt et al.22 reported that five of 14 patients with CRAO had improvement of visual acuity, visual field, or both following intra-arterial urokinase infusion. In a further five patients, no improvement occurred with this therapy. In these five patients, visual acuity was impaired preoperatively for more than seven hours.

Systemic thrombolytic agents were used in a pilot study involving three consecutive patients with acute CRAO.18 The selection of the thrombolytic agent, tPA or anistreplase, was at the discretion of the internist. Patients were treated in the hospital emergency department with cardiovascular monitoring. Intravenous heparin sodium and oral coumadin were given as adjuvant therapy after thrombolytic infusion. All three patients noted subjective improvement within several hours of treatment. The best achieved visual acuity was recorded within 96 hours of therapy (Table 12.318). Nevertheless, whilst the results of these pilot studies are encouraging, outside of a randomized clinical trial, the use of superselective fibrinolytic therapy for CRAO cannot be recommended on the basis of current evidence.23

Another therapy, early hyperbaric oxygen no later than eight hours after the beginning of visual symptoms, is reported to have a beneficial effect on visual outcome in patients with retinal artery occlusion. However, further large scale prospective controlled studies are needed to confirm this.24

Table 12.3

Clinical summary of thrombolytic therapy for three male patients

Patient no./

Pretreatment

Time to

Thrombolytic

Adjunctive

Post-treatment

age (yr)

visual acuity

therapy*

agent

therapy

visual acuity

1/56

Hand motion

5-5

Anistreplase

Intravenous

20/60+

heparin,

aspirin

2/74

Light perception

4-0

Tissue

Intravenous

20/400

plasminogen

heparin, warfarin,

activator

3/61

Hand motion

2-75

Tissue

Intravenous

20/25

plasminogen

heparin, warfarin

activator

Data from Marnes ei al.18

"Time to initiation of thrombolytic therapy in hours.

Data from Marnes ei al.18

"Time to initiation of thrombolytic therapy in hours.

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