Gradual loss of vision Flashcards
What do you ask in the hx of a patient presenting with gradual loss of vision?
The nature of the problem:
- Onset
- Progression
- Ask whether there have been any associated factors.
- Ask whether there are any precipitating factors. Specifically, ask about changes over the course of a day and whether vision is better in the day or at night.
- Other important aspects of the history include the past ocular history, medical history, family history, medication and social history:
- Is this affecting their lifestyle?
- Are there implications with regard to their work or driving?
- Will this mark the loss of their independent living?
Which questions do you ask about the nature of the gradual loss of vision?
- Unilateral versus bilateral.
- Blurred vision: whether this is the whole field, close, distance or both.
- Restricted visual field: often noted following difficulties in driving, knocking into things at the periphery of vision
- Distorted rather than blurred vision (eg, dent in printed words, door/window frames, objects appearing smaller or larger). If so, check with an Amsler grid. Distortion of straight lines indicates serious macular pathology and needs urgent referral.
- Bits of visual field missing altogether: central versus peripheral; establish what the remainder of the vision is like.
Which questions do you ask about the timeline of the gradual loss of vision?
Note when the problem occurred and whether there were any significant health issues at that time.
Ask how it was first noticed. Unilateral visual loss might have gone unnoticed until the patient closed the other eye.
Ask whether there has been a slow and steady decline; whether there have been step-wise drops in visual acuity, or whether the problem has been intermittent. If intermittent, think of transient ischaemic attacks (TIAs) or impending acute angle-closure glaucoma.
What are the associated symptoms you should ask about when enquiring about gradual loss of vision?
For example, pain (very important diagnostically), redness, or visual phenomena – e.g., haloes, flashes of light, new floaters. These symptoms usually merit an urgent referral.
What do you examine in a patient presenting with gradual loss of vision?
The visual acuity of both eyes. Note whether this improves using a pinhole.
The red reflex: a media opacity (appears black against the red reflex) suggests a corneal, lens or vitreous problem. To localise the site of the opacity with respects to the pupil (lens):
- Slowly shift the direction of your ophthalmoscope light.
- Look at the direction in which the opacity appears to move in relationship to the pupillary (central) axis.
- If there is no ‘movement’ of the opacity, it lies within the pupil (lens).
- If the opacity ‘moves’ in the same direction, it is anterior to the lens (cornea).
- If the opacity moves’ in the opposite direction, it is posterior to the pupil (posterior lens or vitreous).
- If the media is clear, it is more likely to be a retinal or optic nerve disorder.
- If there is a normal red reflex, take a good look at the fundus.
Do a functional testing of the visual field, pupils, optic nerve and macula.
Use an Amsler grid to look for distortion of straight lines - if present, this indicates serious macular pathology and needs an urgent referral.
Check blood pressure and urine glucose.
How can you locate the site of a visual defect?
Note that the optic nerve fibres divide and cross over at the optic chiasm, which can help you locate the site of the visual defect:
- Loss of vision in one eye - implies the problem is in the eye itself or in the optic nerve before it reaches the optic chiasm.
- Loss of vision in both temporal fields (bitemporal hemianopia) - occurs from lesions compressing the optic chiasm (eg, pituitary tumour or craniopharyngioma).
- Loss of left or right visual field (homonymous hemianopia) - implies the lesion is somewhere between the optic chiasm and the occiput.
In the eye itself:
- Chronic glaucoma tends to cause tunnel vision (loss of peripheral visual field).
- Macular degeneration causes loss of central vision (central scotoma) and may cause distortion of straight lines.
What are the causes of painless gradual vision loss?
Refractive error Cataracts AMD Chronic open-angle glaucoma Diabetic retinopathy Drugs Hereditary retinal dystrophies Cerebrovascular disease TIA causing visual loss is termed amaurosis fugax Papilledema from intracranial HTN
How does refractive error present?
Refractive error - this is characterised by an improvement of the visual acuity with the use of a pinhole (if you don’t have a specific occluder with pinholes, a biro point-sized hole in a stiff piece of cardboard will do). Refer to the optician.
How do cataracts present?
Cataracts - the patient often complains of glare in dark conditions (and so difficulty in driving at night) and may complain that colours appear duller than they used to.
There may be an abnormal red reflex and, in advanced cases, the cataract may be visible to the naked eye (this is increasingly rare these days).
Other aspects of the examination should be normal unless there is concurrent pathology. Refer routinely.
How does AMD present?
Age-related macular degeneration (AMD) - suspect AMD if the patient is aged >50 years and is presenting with either of the following symptoms, usually affecting one eye at a time:
- Distortion of vision, where straight lines appear crooked or wavy.
- Painless loss or blurring of central or near-central vision. The person may describe a black or grey patch affecting their central field of vision (scotoma).
- Various other visual symptoms can occur, or AMD may be an incidental finding by an optometrist. Visual acuity on a Snellen chart may be normal or reduced. When viewing an Amsler chart (or graph paper), patients may see breaks, waviness, or missing portions of the lines. Refer urgently if AMD is suspected.
How does open-glaucoma present?
Chronic (primary) open-angle glaucoma - is most commonly picked up through screening. If it is so advanced that the patient is the first to notice it, very little can be done. It is characterised by a progressive peripheral visual field loss and ‘cupping’ of the optic discs (the central area of the optic disc enlarges, and the peripheral rim thins out). The degree of urgency depends on how advanced the damage is.
What is the main problem in diabetic retinopathy?
Diabetic retinopathy - the problem may be due to diabetic microvascular problems (i.e. exudates and haemorrhages), associated pathology (e.g., diabetic cataract) or unrelated pathology (e.g., glaucoma). Refer promptly (within a week), as prompt treatment may prevent deterioration.
How does compression of the optic pathway present?
Rare, but should be considered if there is a history of headaches and if you find any neurological or endocrinological abnormalities (e.g., acromegaly) on examination.
Look for a relative afferent pupillary defect (not usually present in the above conditions), a pale or swollen optic disc (the margins are not clear) and visual field defects
Which drugs can cause a gradual loss of vision?
Drugs, toxins or nutritional deficiency - eg:
-Amiodarone - various effects on the eye
-Antituberculous drugs - ethambutol and isoniazid (optic neuritis).
-Hydroxychloroquine (maculopathy).
-Systemic steroids (cataracts and glaucoma)
-Phosphodiesterase inhibitors (eg, sildenafil).
-Other drugs - tetracyclines (benign intracranial hypertension), isotretinoin, tamoxifen (various possible effects on vision).
-Alcohol, smoking and nutritional deficiency - eg:
Tobacco-alcohol amblyopia.
Methanol poisoning.
-Vitamin A deficiency (classically causes night blindness.
How does hereditary retinal dystrophies present?
Hereditary retinal dystrophies are rare and, depending on the exact problem, present anywhere from early childhood to middle age. Some are rapidly progressing; others are very slow.
Typical features particularly include poor night vision and intolerance to light. Poor appreciation of movement in the peripheral visual field may also be a feature.
Ask about similar problems in family members (who may not have been diagnosed). Children should be referred more promptly than adults for whom a routine referral is fine. These patients will need genetic counselling as well as support where the prognosis is poor.
