Blurred vision and angle closure glaucoma Flashcards
What is a blurred vision?
Blurred vision - a single image that is seen indistinctly. Establish whether this is at distance, near or both.
What are other interpretations of blurred vision?
A decrease in peripheral vision - the patient may describe bumping into things or frequent scrapes when parking the car.
Alteration of a clear image - e.g., micropsia/macropsia (image appears smaller or bigger) or metamorphopsia (distorted image).
Interference with a clear image (e.g., floaters, flashes of light - photopsia).
Diplopia - monocular (the double vision remains when the uninvolved eye is occluded); binocular (the vision returns to normal on covering one eye), horizontal, vertical, oblique.
Other disturbances of vision - e.g., iridescent vision (haloes, rainbows), dark adaptation problems or night blindness (nyctalopia), colour vision abnormalities.
What should you ask in the hx of blurred vision?
Note whether it is unilateral or bilateral.
Ask whether it was sudden or gradual in onset. If sudden, ask what the patient was doing at the time; ask what they have done recently that may have affected the eyes - eg, DIY, trauma. If gradual, ask over what period of time it has developed.
Note whether it has happened before. Note when, and what happened. Ask whether it has been diagnosed.
Establish whether there are any associated factors. Examples include any of the other visual phenomena described above, pain (distinguish between ocular pain and pain in the head), associated ocular complaints (eg, red-eye, discharge, abnormal appearances) or systemic complaints (eg, headache, other neurological problems, generalised malaise).
What are the causes of unilateral, sudden and painful blurred vision?
Trauma
Orbital cellulitis: the area surrounding the eye will be hot, red, swollen and tender and the patient will be systemically unwell.
Endophthalmitis: associated with accidental or surgical trauma which may be recent or old but may also be endogenous. Look for the painful red eye, reduced visual acuity and a hypopyon.
Corneal problems: trauma, infection, severe dry eye or exposure keratopathy, contact lens problems.
Anterior uveitis: red-eye associated with photophobia, headache - may be previous episodes.
Acute angle-closure glaucoma: often precipitated when the pupil is in mid-dilation (e.g. watching television in dim conditions), often associated with systemic malaise (headache, nausea, vomiting).
Arteritic anterior optic neuropathy - giant cell arteritis (temporal arteritis): (patients >50 years old) - the pain is often more a headache than acute eye pain; other features include jaw claudication, scalp tenderness, polymyalgia rheumatica ± anorexia, weight loss, fever.
Optic neuritis: (can be bilateral) can be a very painful presentation of multiple sclerosis - look for pain, particularly on moving the eye. There may be other focal neurological symptoms.
Migraine: when there are scintillations, the pain in the head often appears when the visual disturbance is ebbing or has disappeared.
What are the causes of unilateral, sudden and painless blurred vision?
Vitreous haemorrhage: may also present as sudden floaters.
Central retinal artery occlusion presents with painless, almost instantaneous, reduction of vision in one eye.
Central retinal vein occlusion frequently presents with loss of vision or blurred vision, often starting on waking.
AMD - in the majority of cases, this is the ‘dry’ form which is associated with a progressive decrease in visual acuity. However, in about 10% of cases, the ‘wet’ form occurs where a neovascular membrane forms which may be susceptible to bleeding, so causing a dramatic and rapid loss of vision.
Retinal detachment tends to produce a ‘curtain’ coming across the visual field rather than blurring of vision.
Intermediate or posterior uveitis - this tends to present with marked floaters ± blurring of vision rather than the painful red eye characteristic of anterior disease.
Anterior ischaemic optic neuropathy - look for a relative afferent pupillary defect, a pale and oedematous optic disc, flame-shaped haemorrhages and possibly an altitudinal visual field defect.
Hydrops - acute corneal oedema may arise in a number of conditions such as keratoconus.
Cerebrovascular disease - this usually causes visual disturbance in both eyes but should be considered when a patient presents with unilateral blurred vision.
What are some causes of vitreous haemorrhage?
It may arise as a result of diabetic retinopathy, a retinal break or detachment, retinal vein occlusion and, occasionally, a posterior vitreous detachment or age-related macular degeneration (AMD). Also, consider it in trauma, subarachnoid or subdural haemorrhage, intraocular tumours and sickle cell disease. It can occur in other more unusual situations too.
What are the systemic causes of blurred vision?
Giant cell arteritis (temporal arteritis)
Papilledema - optic disc swelling secondary to raised intracranial pressure may give rise to headache rather than eye pain. Visual abnormalities tend to be transient initially.
Amaurosis fugax - this characteristically presents as a curtain across the vision and may be associated with intraocular emboli, atrial fibrillation and carotid bruits.
Migraine prodrome - this may occur in some people without the following headache. It is usually unilateral but may progress to be homonymous.
Toxic illness - it is apparent that the patient is pyrexial and unwell.
What are the causes of bilateral, sudden and painful blurred vision?
Arc eye, as in welders. There will probably be a history of welding a number of hours earlier with inadequate protection and often the patient will offer the diagnosis.
Beware of malignant hypertension in the susceptible patient who develops rapidly progressing blurring of vision bilaterally (not necessarily equally). Pain tends to be in the form of headaches.
What are the causes of bilateral, sudden and painless blurred vision?
Papilloedema.
Cerebrovascular disease may lead to damage to the visual pathways and optic cortex. There may or may not be macular sparing. Visual disturbance is often homonymous
Drugs - anticholinergic drugs but also sedative drugs like antipsychotics and anticonvulsants. The onset of effect of these drugs can be quite slow.
Refractive errors tend to change very slowly over years but, in poorly controlled diabetes mellitus, they may change more rapidly. Drugs like steroids and anticholinergics can also have this effect.
What are the causes of bilateral/unilateral, gradual and painless blurred vision?
Glaucoma - this is characterised by asymptomatic but progressive peripheral visual field loss which is usually bilateral but asymmetric.
Refractive errors - hormonal changes, such as occur during pregnancy, can affect the refractive error but this reverts on restoration of baseline hormone levels. Progression of corneal disease such as dystrophies or keratoconus can also cause gradual visual loss.
Cataracts - the patient may also complain of dulling of colours (and may be noted by relatives to have a predilection for very bright or gaudy colours!). Think of cataracts in patients with diabetes and those on systemic steroids and immunosuppressants (eg, transplant patients).
AMD - dry form.
Cystoid macular oedema - this may occur as a result of surgery, inflammation or vascular disease.
Diabetic maculopathy - ischaemia may lead to gradual decrease in visual acuity whereas oedema tends to result in more acute visual distortion.
Genetic disease - there are many degenerative conditions that can cause blurring of the vision. These may affect the elements of the visual media (eg, the cornea in keratoconus) or the retina (eg, Best’s disease).
Drug toxicity - for example, hydroxychloroquine, methanol, ethambutol and, more recently, it has been described with COX-2 inhibitors.
Other toxic agents - including exposure to organophosphates.
Inflammatory optic neuropathies - these tend to be associated with systemic diseases such as sarcoid, vasculitis or syphilis.
Chronic eye strain - as with excessive use of computers under adverse conditions, may produce blurred vision.
What are the causes of unilateral, gradual and painful blurred vision?
Neoplastic or inflammatory disease of the orbit and globe.
What are the causes of medically unexplained vision loss?
This can occur in four circumstances:
- Organic disease has not been diagnosed.
- The patient is a malingerer with secondary gain.
- The visual loss is psychosomatic.
- Münchhausen’s syndrome (or fabricated or induced illness by carers - formerly known as Münchhausen’s syndrome by proxy).
Note: deciding that there is no underlying organic disease is difficult and not advisable without a specialist opinion. You may note some features or be aware of some aspects of the patient’s situation that raise the question in your own mind and, depending on circumstances, it may be worth mentioning these to the ophthalmology team.
Malingerers tend to have a unilateral visual loss, whereas functional loss tends to be bilateral.
What is the management of blurred vision?
As a rule of thumb, acute, painful conditions warrant same day referral. A suspected case of giant cell arteritis (temporal arteritis) - where the patient doesn’t necessarily have eye pain - and central retinal artery occlusion also need prompt referrals.
Check the guidance from the DVLA regarding a patient’s ability to drive. This will depend on the nature of the visual problem and the underlying cause.
What is angle-closure glaucoma?
Angle-closure glaucoma (ACG) is a condition of acutely raised intraocular pressure (IOP) associated with a physically obstructed anterior chamber angle.
It is divided into primary and secondary types and the distinction is important as the treatments vary. Both primary and secondary types may cause acute painful attacks or chronic asymptomatic disease.
How does the aqueous humor flow in the normal eye?
In the normal eye, aqueous humor is produced by the ciliary body behind the iris and flows through the pupil to drain into the trabecular meshwork which lies around the circumference of the angle between the iris and the cornea.
This junction of the iris and cornea at the periphery of the anterior chamber is the anterior chamber angle.
Occasionally, the iris can become apposed to the trabecular meshwork and so block off the aqueous drainage. This results in a rise in IOP which causes a number of symptoms and signs, depending on the type of angle closure.
