Sudden Onset Double Vision Eye Series – 11

EDUCATION: Eye series

Sudden onset double vision Eye series – 11

Chris Hodge, BAppSc, DOBA, is Research Director, The Eye Institute, Chatswood, New South Wales. Frank Martin, MBBS, FRANZCO, FRACS, is an ophthalmic surgeon, Sydney, and The Eye Institute, Chatswood, New South Wales.

A 50 year old woman presents complaining of double vision. She had become aware of double images while watching television the previous night. There was no associated pain or headache. Apart from being overweight the patient is relatively healthy. She is on no current medication. There is a strong family history of diabetes. On observation the patient’s right eye is turning inward (Figure 1).

Question 1 Answers What are the main causes of acquired Figure 1. Patient with inward turning eye Answer 1 double vision? Acquired double vision can be either macular degeneration. This should Question 2 monocular or binocular in nature. become apparent on further questioning. Monocular diplopia is commonly due to What are the critical features in the abnormalities of the eye: Answer 2 history to make a diagnosis? • uncorrected refractive error (particu- Careful history taking will help define the Question 3 larly high astigmatism) patient examination and may be as • subluxated natural lens (systemic con- important as the clinical tests. The follow- Which cranial nerves are involved in eye ditions such as Marfan’s syndrome) ing questions will help provide direction movement and how does palsy of each of • cataract to the final diagnosis: these nerves affect eye position? • retinal disease. • monocular or binocular – if the diplopia Question 4 In the normal situation both eyes work continues when one eye is closed the together to form a single image. condition is monocular. If the diplopia List the most common causes of sixth Binocular diplopia occurs when the rela- disappears it is due to a breakdown in nerve palsies. tionship is disrupted. The breakdown may the binocularity of both eyes Question 5 be either neurological or mechanical in • onset – sudden onset may indicate vas- origin. Causes include: cular origin while gradual What further investigations should be • cranial nerve palsies (from trauma, deterioration may be due to a progres- undertaken? intracranial lesions, diabetes) sive neurological disorder such as Question 6 • extraocular muscle weakness (from progressive supranuclear palsy or a cranial nerve palsy) exacerbates slow growing tumour Describe the usual prognosis of acquired diplopia • vertical or horizontal – the direction of sixth nerve palsy. • direct trauma to the eye (orbital wall frac- the double image may indicate the spe- Question 7 tures causing mechanical restriction or cific involvement of an extraocular entrapment of the extraocular muscles). muscle. (Similarly some extraocular What is the most appropriate treatment? It is important to differentiate between muscles will dominate with either close diplopia and a distortion of the vision or distance vision. For example, a sixth (metamorphopsia) as commonly produced nerve or lateral rectus palsy will be more by retinal disorders such as age related noticeable when the patient is viewing a

1016 • Reprinted from Australian Family Physician Vol. 31, No. 12, December 2002 Sudden onset double vision n

acquired palsy. Tumours, viral disease (eg. ery. To help correct the diplopia, stick- meningitis), elevated intracranial pressure on prisms (Fresnel prisms) can be and various inflammatory disorders (eg. applied to glasses to realign the images multiple sclerosis) are also known causes and provide comfort to the patient. of acquired abducens palsy. Although These prisms will need to be adjusted more common in fourth cranial nerve regularly as the eye recovers. If the palsies trauma may also lead to an patient finds the prisms difficult to use or acquired sixth palsy. confusing, occlusion of the affected eye It is important to differentiate between will serve to remove the diplopia albeit Figure 2. MRI of orbital lesion leading true sixth nerve palsy and conditions that at the loss of depth perception. These to disruption of ocular movement through may also lead to decreased horizontal patients should be warned about the lateral rectus involvement movement. Orbital wall fractures or intra- potential hazards of operating with only orbital growths may inhibit lateral rectus one eye (eg. difficulty negotiating stairs distant object). Neurological disorders movement and mimic abducens palsy or judging distances when driving). usually lead to vertical diplopia (Figure 2). Myasthenia gravis can also Botulinum toxin may be used in special • associated symptoms – motor symp- produce similar symptoms although pre- cases to reduce the possible contracture toms such as ataxic gait may indicate sentation is variable with periods of of the opposing muscle (medial rectus). an associated progressive neurological exacerbations and remissions. This would Contracture of the muscle may reduce the disorder. help to serve as a differential diagnosis. effectiveness of future surgery. Because the majority of acquired palsies Answer 3 Answer 5 recover naturally, surgery should not be The extraocular muscles are controlled by If the underlying cause remains undeter- considered unless the condition has sta- three cranial nerves: mined further investigation is required. A bilised or muscle function assessed as • the oculomotor nerve (third) controls full screening for diabetes and hyperten- permanently reduced at 12 months. The the superior, inferior and medial recti sion should be undertaken. If the patient aim of surgery is to restore binocular muscles as well as the inferior oblique is over 60 years of age an erythrocyte sed- vision in the primary position and assist muscles. A complete third nerve palsy imentation rate (ESR) test is indicated to further muscle movement thereby will leave the patient with the affected rule out giant cell arteritis. If results increasing the area of single vision and eye turning down and outward. (The return negative more descriptive tests improving patient comfort. This should patient will also have a lid ptosis and such as CT or MRI scans should be com- be the final option. dilated pupil) pleted to rule out potential neurological

• the trochlear or fourth nerve controls lesions. The presence of additional neuro- Conflict of interest: none declared. AFP the superior oblique muscle. A patient logical signs should represent an with a fourth nerve palsy will often emergency and require urgent consulta- present with a hypertropia of the tion with a neurologist. affected eye (one eye higher than the other in primary or normal gaze). To Answer 6 compensate for the loss of movement An acquired sixth nerve palsy of microvas- the patient will commonly tilt their cular origin will usually resolve in 3–6 head to the opposite shoulder months without treatment. If the underly- • the abducens, or sixth nerve, controls the ing cause is due to a lesion, the defect will lateral rectus. A sixth nerve palsy will not resolve until this is removed. About cause the eye to turn inward, increasing one-third of patients may experience a when looking to the affected side. further episode at a later stage. Similarly a palsy of viral origin retains an excellent Answer 4 prognosis for recovery. The most common cause of sixth nerve palsy is microvascular disease. The patient Answer 7 may present with a history of diabetes, The patient should be followed regularly hypertension or hypercholesterolaemia. during the initial stages of the condition Giant cell arteritis can also lead to an to monitor change and potential recov-

Reprinted from Australian Family Physician Vol. 31, No. 12, December 2002 • 1017