Loss of vision is an important clinical feature that patients may present with. Causes of loss of vision can be divided into sudden or gradual loss of vision. This article will deal with the common and important conditions associated with loss of vision.
History and examination
Some information to obtain from the history:
The following must be performed in the examination of a patient with loss of vision
Sudden loss of vision is a very important clinical feature and may require urgent treatment. Causes include ischaemic optic neuropathy, retinal artery or vein occlusion, vitreous haemorrhage and optic neuritis. Other causes include stroke, transient ischaemic attack (TIA) and migraine. More information about the conditions mentioned below can be read in the 'Conditions' section.
Anterior ischaemic neuropathy
Ischaemic optic neuropathy (ION) can be arteritic (i.e. due to inflammation of the posterior ciliary artery in giant cell arteritis (GCA), seen in patients above age 60) or non-arteritic (e.g. associated with hypertension, hyperlipidaemia, diabetes, smoking - caused by blockage of the posterior ciliary artery).
In arteritic ION, patients present with the following clinical features:
Investigations will reveal the following:
In non-arteritic ischaemic optic neuropathy, field loss is often predominantly in the superior or inferior field, a pattern known as altitudinal.
Figure 1: Anterior ischaemic optic neuropathy: Note the pale, swollen optic discs.
Central retinal artery occlusion
Often caused by thromboembolic occlusion such as a clot or tumour. Patients may have risk factors such as hypertension, hyperlipidaemia, diabetes, smoking. A carotid bruit suggests athero-thromoboembolism.
If a branch of the retinal artery is affected, only a sector of the retina opacifies, producing only a partial loss of vision. The underlying cause is more likely to be an embolus than in a central artery occlusion.
Figure 2: Picture of a fundus of the right eye showing central retinal artery occlusion: Note the pale retina and the "cherry red spot" (found temporal to the optic disc) of central retinal artery occlusion.
Central retinal vein occlusion
This is commoner than retinal artery occlusion and has a higher incidence amongst older patients. Causes include: hypertension, atherosclerosis, diabetes, polycythaemia. It can be further categorised as ischaemic or non-ischaemic.
Further complications for patients with central retinal vein occlusion includes macular oedema and neovascular glaucoma ('100 days glaucoma').
Figure 3: Picture of fundus showing central retinal vein occlusion. Note the "blood and thunder" appearance caused by extensive haemorrhages.
Figure 4: Another picture of central retinal vein occlusion. Observe the dilated, tortuous veins supero- and infero-temporally in the picture and the widespread superficial haemorrhages.
Branch retinal vein occlusion
Patients present with unilateral vision loss and fundoscopy will reveal haemorrhages in the affected part of the retina. Macular oedema and retinal neovascularisation also occurs.
Figure 5: A fundus showing branch retinal vein occlusion. In contrast to the extensive haemorrhages seen in central retinal vein occlusion, branch occlusion will show bleeding in one segment of the retina only. In this picture, there is a focal area of bleeding found lateral or temporal to the optic disc, suggesting branch retinal vein occlusion.
Associated with trauma, retinal detachments, retinal tears and retinal neovascularisation (e.g. diabetes, retinal vein occlusion). May also accompany subarachnoid haemorrhages.
Patient present with the following:
Typically patients complain of photopsia followed by large number of floaters and then a shade over the vision. If detachment is extensive enough, it can produce a relative afferent pupillary defect.
Fundoscopy may show elevated parts of the retina, sometimes with folds and indistinct choroidal background.
Figure 6: A picture of a fundus showing retinal detachment. Note the elevated folds of the retina in the temporal segments. Patients may also have vitreous haemorrhages associated with the detachment.
Other causes of sudden loss of vision:
Common causes of gradual loss of vision includes the following:
(More information about the above conditions can be read in the 'Conditions' section)
Suspect cataracts as a cause of gradual loss of vision if patients present with blurring of vision, frequent changes in glasses prescription due to changes in the refractive index of the lens and dazzling in sunlight.
Age-related macular degeneration (ARMD)
Common cause in the elderly with deterioration of central vision. On fundoscopy, dry ARMD reveals mainly drusen and degenerative changes in the macula. In wet ARMD, choroidal neovascularisation occurs and this can cause fluid exudation and localised detachment of the pigment - vision distortion and deterioration may occur rapidly.
Figure 7 Picture of a fundus showing drusen in dry age-related macular degeneration. Note the yellow deposits (drusen) in the macular region.
Chronic simple (open angle) glaucoma is an important cause of gradual vision loss as patients may be asymptomatic for years until vision is severly impaired and optic nerve damage is irreversible. Visual field examination may reveal sausage-field defects (scotomata) near the blind spot. The nasal and superior fields are usually lost first. Because the central field remains intact, patients usually have good acuity.
On fundoscopy, optic disc cupping may be seen, with optic atrophy in the later stages. Blood vessels can appear to have breaks throughout their course as they emerge from the disc, disappear into the cup and are seen at the base again. Haemorrhage at the disc is a significant feature.
Figure 8. Picture showing changes in chronic open-angle glaucoma. Observe the pallor of the optic disc and increased cupping.
Usually patients are asymptomatic but since it is the leading cause of blindness in the UK in those aged 20-65, it is important to look out for signs of retinopathy. Patients may describe features of vitreous haemorrhage and/or retinal detachment in severe proliferative retinopathy. In maculopathy, patients may complain of severe deterioration in visual acuity.
Features on fundoscopy include microaneurysms ('dots'), haemorrhages ('blots') and hard exudates - these are features seen in non-proliferative diabetic retinopathy. The presence of engorged tortuous veins, cotton wool spots (areas of ischaemia) and large blot haemorrhages suggest significant ischaemia. Fine new vessels on the optic disc and retina suggests proliferative diabetic retinopathy.
Figure 9. This is a picture showing the retinal findings in background retinopathy. Note the presence of blot hemorrhages (arrowhead), microaneurysms (short arrow), and hard exudates (long arrow).
Patients are usually asymptomatic and there is a gradual decline in visual acuity. Fundoscopy may reveal hard exudates, haemorrhages and arteriovenous nipping. The arterial walls can be thick and shiny and appear like 'silver' or 'copper' wiring. Areas of localised infarction due to arteriolar vasoconstriction can create cotton wool spots and flame-shaped haemorrhages. In severe cases there may be macular oedema and papilloedema.
The clinical features depend on the underlying cause of the atrophy - glaucoma, retinal artery occlusion, choroiditis, retinitis pigmentosa or toxins such as tobacco, methanol and lead. Patients may be asymptomatic or have gradual deterioration in vision. The degree of paleness of the optic disc doesn't always correlate with visual loss.
Figure 10. Picture showing optic atrophy. Note the pallor of the optic discs. In this figure, the atrophic discs are caused by primary optic atrophy.
Figure 11. Another picture showing optic atrophy. In this case, the atrophy is secondary to glaucoma.
Slow retinal detachment
Patients present with the 4 F's: floaters, flashes, field loss and a fall in acuity. The loss of vision is painless and patients may describe a "curtain falling over the vision". Loss of central vision suggests extensive detachment affecting the macula. The field defects help indicate the position and extent of detachment. Fundoscopy may reveal parts of the retina ballooning forwards (see Figure 6).
This malignant tumour can cause retinal detachment over the tumour growth and patients may be asymptomatic or present with features of retinal detachment or progressive visual field loss. On fundoscopy, the lesion appears as mottled grey or black on the retina.
Figure 12: Picture of a fundus showing a choroidal melanoma. There is a dome-shaped pigmented choroidal melanoma in the periphery of the fundus in the picture.
Loss of vision can be a very distressing experience for the patient. A thorough history and examination can help find clues as to the cause of the vision loss. Early and accurate diagnosis and timely management can lead to a positive outcome.
Some causes of loss of vision such as retinal artery occlusion, ischaemic optic neuropathy and retinal detachment need urgent help and it is important to be familiar with the signs and symptoms of these conditions so there can be no delay in referral to a specialist. Also be aware of the possibility of an acute discovery of chronic visual loss.
Figure 1: Younge, BR. Anterior ischaemic optic neuropathy. [online image] 2010. [cited 2011 December 14]. Available from: http://emedicine.medscape.com/article/1216891-overview
Figure 2: Jain, N. The cherry red spot of central retinal artery occlusion [online image] 2009 [cited 2011 December 14] Available from: http://emedicine.medscape.com/article/799119-overview
Figure 3: Kooragayala, L. Recent onset retinal vein occlusion, showing extensive haemorrhages in the posterior pole and giving the "blood and thunder" appearance. [online image] 2011. [cited 2011 December 14]. Available from: http://emedicine.medscape.com/article/1223746-overview
Figure 4: Kooragayala, L. Patient with nonischaemic retinal vein occlusion presented with dialted, tortuous veins and superficial haemorrhages. [online image] 2011. [cited 2011 December 14]. Available from: http://emedicine.medscape.com/article/1223746-overview
Figure 5: Wu, L. This 42-year old woman with hypertension noticed a sudden decrease in her vision. Visual acuity was 20/100. Note the intraretinal haemorrhages in one segment of the retina. [online image] 2011 [cited 2011 December 14]. Available from: http://emedicine.medscape.com/article/1223498-overview
Figure 6: Larkin, G. Retinal detachment [online image] 2010 [cited 2011 December 14]. Available from: http://emedicine.medscape.com/article/798501-overview
Figure 7: Maturi, RM. Moderate nonexudative age-related macular degeneration is shown with the presence of drusen (yellow deposits) in the macular region. [online image] 2011. [cited 2012 January 4] Available from: http://emedicine.medscape.com/article/1223154-overview
Figure 8. Bell, JA. Advanced glaucomatous damage with increased cupping and substantial pallor of the optic nerve head. [online image] 2011. [cited 4 January 2012] Available from: http://emedicine.medscape.com/article/1206147-overview
Figure 9. Bhavsar, AR. Retinal findings in background diabetic retinopathy, including blot hemorrhages (arrowhead), microaneurysms (short arrow), and hard exudates (long arrow). [online image] 2011. [cited 2012 January 6] Available from: http://emedicine.medscape.com/article/1225122-overview
Figure 10: Ghandi, R. Primary optic atrophy [online image] 2011 [cited 2012 January 6] Available from: http://emedicine.medscape.com/article/1217760-overview
Figure 11: Ghandi, R. Glacomatous optic atrophy [online image] 2011 [cited 2012 January 6] Available from: http://emedicine.medscape.com/article/1217760-overview
Figure 12: Garcia-Valenzuela, E. Colour photograph of a dome-shaped choroidal melanoma. [online image] 2011. [cited 2011 December 14] Available from: http://emedicine.medscape.com/article/1190564-overview
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