Ophthalmology
Question 9 of 97
A 37 year old woman presents to the Emergency Department complaining of right eye pain and associated decreased vision over the last 2 days. On examination you note a central scotoma and a relative afferent pupillary defect. What investigation is used to confirm the most likely diagnosis in this patient?
Answer:
The patient has signs and symptoms of optic neuritis. MRI of the optic nerves is the most appropriate investigation- findings support the diagnosis of optic neuritis (ON) and rule out other causes of optic nerve damage such as compressive neuropathy; it is also helpful for predicting conversion to clinically definite multiple sclerosis (CDMS).Optic Neuritis
Ophthalmology
Last Updated: 8th September 2021
Optic neuritis (ON) is inflammation of the optic nerve. By far the most common form is idiopathic ON, which is a primary demyelinating disease occurring in isolation or as part of multiple sclerosis (MS).
Risk factors
- Age 30 - 50 years
- Female gender
- White ethnicity
Clinical features
- Symptoms
- Partial or total unilateral visual loss occurring over several days
- Periorbital/retro-ocular pain exacerbated by eye movements
- Colour desaturation/loss of colour vision
- Signs
- Reduced visual acuity with a scotoma affecting central vision
- Decreased ability to differentiate colours (using Ishihara charts)
- Relative afferent pupillary defect
- Optic disc swelling (may or may not be present)
Management
- Urgent ophthalmology referral
- MRI of the optic nerves - findings support the diagnosis of optic neuritis (ON) and rule out other causes of optic nerve damage such as compressive neuropathy, also helpful for predicting conversion to clinically definite multiple sclerosis (CDMS)
- Treatment is usually with corticosteroid therapy
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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 |
