Ophthalmology
A 71 year old man presents to the Emergency Department with a sudden, painless, loss of vision in the left eye. On fundoscopy you note a pale retina. You make an urgent referral to ophthalmology as you suspect central retinal artery occlusion. Which of the following is NOT a treatment that is indicated whilst awaiting ophthalmology review?
Answer:
- Central retinal artery occlusion (CRAO) has a poor prognosis for spontaneous recovery of vision. Efforts to restore vision should begin emergently, as irreversible retinal injury occurs within 100 minutes of arterial occlusion. However, no treatments currently available have been proven to improve visual outcomes.
- 'Standard' treatments:
- To fluctuate intraocular pressure and manually dislodge clot
- Digital orbital massage
- To decrease intraocular pressure
- Intravenous acetazolamide, intravenous mannitol or topical pressure-lowering drops e.g. timolol
- Anterior chamber paracentesis
- To increase ocular blood flow (vasodilation)
- Vasodilator medications e.g. sublingual isosorbide dinitrate
- Inhaled carbogen therapy
- To maintain oxygenation of the retina pending reperfusion
- Hyperbaric oxygen therapy
- Revascularisation techniques
- Intra-arterial thrombolytic therapy
- Surgical revascularisation techniques
- To fluctuate intraocular pressure and manually dislodge clot
Retinal Artery Occlusion
Ophthalmology
Last Updated: 12th February 2021
Central retinal artery occlusion (CRAO) presents with acute, painless loss of monocular vision. This disorder is considered a form of stroke, with a similar clinical approach and management; the clinician attempts to treat the acute event, find the source of the vascular occlusion, and prevent further vascular events from occurring.
Clinical anatomy
The central retinal artery arises from the ophthalmic artery, itself a branch of the internal carotid artery. The central retinal artery supplies the inner retina and the surface of the optic nerve.
Causes
- Carotid artery atherosclerosis (most common)
- Cardiogenic embolism
- E.g. atrial fibrillation
- Small artery disease (local atheroma within central retinal artery)
- Haematological disease
- E.g. sickle cell disease, hypercoagulable states, thrombophilic disorders
- Inflammatory disease
- E.g. giant cell arteritis
Clinical features
- Acute painless profound unilateral loss of vision
- Relative afferent pupillary defect
Fundoscopy findings
- Ischaemic retinal whitening
- Cherry red spot at the macula
Management
- CRAO has a poor prognosis for spontaneous recovery of vision. Efforts to restore vision should begin emergently, as irreversible retinal injury occurs within 100 minutes of arterial occlusion. However, no treatments currently available have been proven to improve visual outcomes.
- 'Standard' treatments:
- To fluctuate intraocular pressure and manually dislodge clot
- Digital orbital massage
- To decrease intraocular pressure
- Intravenous acetazolamide, intravenous mannitol or topical pressure-lowering drops e.g. timolol
- Anterior chamber paracentesis
- To increase ocular blood flow (vasodilation)
- Vasodilator medications e.g. sublingual isosorbide dinitrate
- Inhaled carbogen therapy
- To maintain oxygenation of the retina pending reperfusion
- Hyperbaric oxygen therapy
- Revascularisation techniques
- Intra-arterial thrombolytic therapy
- Surgical revascularisation techniques
- To fluctuate intraocular pressure and manually dislodge clot
- Long-term management to prevent vascular events is cause specific
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- Biochemistry
- Blood Gases
- Haematology
| Biochemistry | Normal Value |
|---|---|
| Sodium | 135 – 145 mmol/l |
| Potassium | 3.0 – 4.5 mmol/l |
| Urea | 2.5 – 7.5 mmol/l |
| Glucose | 3.5 – 5.0 mmol/l |
| Creatinine | 35 – 135 μmol/l |
| Alanine Aminotransferase (ALT) | 5 – 35 U/l |
| Gamma-glutamyl Transferase (GGT) | < 65 U/l |
| Alkaline Phosphatase (ALP) | 30 – 135 U/l |
| Aspartate Aminotransferase (AST) | < 40 U/l |
| Total Protein | 60 – 80 g/l |
| Albumin | 35 – 50 g/l |
| Globulin | 2.4 – 3.5 g/dl |
| Amylase | < 70 U/l |
| Total Bilirubin | 3 – 17 μmol/l |
| Calcium | 2.1 – 2.5 mmol/l |
| Chloride | 95 – 105 mmol/l |
| Phosphate | 0.8 – 1.4 mmol/l |
| Haematology | Normal Value |
|---|---|
| Haemoglobin | 11.5 – 16.6 g/dl |
| White Blood Cells | 4.0 – 11.0 x 109/l |
| Platelets | 150 – 450 x 109/l |
| MCV | 80 – 96 fl |
| MCHC | 32 – 36 g/dl |
| Neutrophils | 2.0 – 7.5 x 109/l |
| Lymphocytes | 1.5 – 4.0 x 109/l |
| Monocytes | 0.3 – 1.0 x 109/l |
| Eosinophils | 0.1 – 0.5 x 109/l |
| Basophils | < 0.2 x 109/l |
| Reticulocytes | < 2% |
| Haematocrit | 0.35 – 0.49 |
| Red Cell Distribution Width | 11 – 15% |
| Blood Gases | Normal Value |
|---|---|
| pH | 7.35 – 7.45 |
| pO2 | 11 – 14 kPa |
| pCO2 | 4.5 – 6.0 kPa |
| Base Excess | -2 – +2 mmol/l |
| Bicarbonate | 24 – 30 mmol/l |
| Lactate | < 2 mmol/l |
