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Loss of Vision

 

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:

  • Patient's age and medical history
  • Is the visual loss transient, persistent or progressive?
  • Monocular or binocular visual loss
  • Severity of the visual loss
  • Onset of visual loss - acute or gradual over hours/days/weeks
  • Pain and other symptoms associated with the visual loss

 

Examination: 

The following must be performed in the examination of a patient with loss of vision

  • Testing visual acuity
  • Confrontation visual field testing - some patients with normal acuity might have loss of peripheral vision
  • Pupillary reactions e.g. is there a relative afferent pupillary defect? 
  • Ophthalmoscopy - the most important examination technique
  • Penlight/Slit lamp examination - to detect corneal disease responsible for acute visual loss
  • Tonometry - to measure intraocular pressure to help confirm angle-closure glaucoma. 

 

    Sudden 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:

    • Scalp tenderness
    • Jaw claudication
    • Malaise
    • Neck pain
    • Patients may have features of polymyalgia rheumatica (anorexia, weight loss, general malaise, aching/fatigue of the upper arms or legs)
    • Fundoscopy may reveal pale or swollen optic discs, often accompanied by splinter haemorrhages, loss of visual acuity and visual field

     

    Investigations will reveal the following:

    • Raised ESR
    • Raised CRP
    • Temporal biopsy - giant cell arteritis (although skip lesions occur).

     

    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.

    Anterior ischaemic optic neuropathy

     

    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.

     

    Clinical features:

    • Sudden loss of vision
    • Afferent pupillary defect
    • Fundoscopy: pale, white retina with cherry red spot in the macula
    • Optic disc does not swell unless the occlusion is in the ophthalmic or carotid artery, proximal to the origin of the central retinal artery or in the small vessels supplying the disc

     

    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. 

    Clinical features: 

    • Acute loss of acuity - visual loss may be severe, although onset is generally subacute
    • Disc swelling
    • Fundoscopy reveals a hyperaemic, haemorrhagic retina in all quadrants ("blood and thunder"), with dilated tortuous veins
    • Cotton-wool spots

    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.

     

     

    Vitreous haemorrhage 

    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: 

    • Small black dots in the visual field - 'vitreous floaters' caused by small extravasation of blood. 
    • Lights or flashes (photopsia) preceding the visual loss suggests retinal detachment. 
    • A large bleed may obscure vision; fundoscopy may show an absent red reflex and the retina may not be seen, but the lens appears clear. 

     

     

    Retinal detachment

    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:

    • Stroke
    • TIA - a relatively common cause of transient visual loss. Ask the patient if vision loss is "like a curtain descending" (amaurosis fugax). Examine for source of the embolus e.g. carotids, heart and valves.
    • Migraine
    • Multiple sclerosis - in optic neuritis, there is subacute loss of vision with afferent pupillary defect and painful eye movements. Patients may also complain that colors appear desaturated/washed out. Optic disc may appear hyperaemic and swollen.
    • Subacute glaucoma
    • Papilloedema

     

    Gradual loss of vision

     

    Common causes of gradual loss of vision includes the following:

    • Cataract
    • Age-related macular degeneration
    • Glaucoma
    • Diabetic retinopathy
    • Hypertension
    • Optic atrophy
    • Slow retinal detachment
    • Choroidal melanoma

     

    (More information about the above conditions can be read in the 'Conditions' section)

     

     

    Cataract

    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. 

     

    Glaucoma

    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. 

     

    Diabetic retinopathy

    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).

     

    Hypertension

    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.

     

     

    Optic atrophy

    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).

     

     

    Choroidal melanoma

    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. 

     

     

    Summary

    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.

     

    References

    • Collier, J., Longmore, M., Turmezei, T. and Mafi, A.R. Oxford handbook of Clinical Specialties. 8th edition. Oxford: Oxford University Press; 2009.
    • Harper, R. A. Basic ophthalmology. 9th edition. USA: American Academy of Ophthalmology; 2010.

     

    Images from:

      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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