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Reduced Vision
Dr Michael Johnson
PhD FCOptom DipOrth DipGlauc DipTp(IP)
Johnson & Furze Optometrists, Thornbury
• Mechanisms
• Differential diagnosis
• Patient scenarios in community practice:
• What should you ask?
• What should you examine?
• When, where and how urgent should be any referral?
Outline
• Eye problems – 3 red flag Ps
• Poor vison - especially sudden loss or distortion
• Pain
• Photophobia
• Consider vascular or neurological disease
• Recognise limitation when not simple trauma
Summary
• Defocus
• Opacification of normally clear media
• Retinal abnormality
• Visual pathway problems
Mechanisms of reduced vision
• Wet AMD
• Vascular
• Retinal vascular occlusions
• Ischaemic optic neuropathy
• Vitreous haemorrhage
• TIA & CVA
• Retinal detachment
Rapid loss of sight (common)
• Defocus
• Ammetropia + Presbyopia
• Cataract
• Maculopathy
• AMD (atrophic) + Epiretinal membrane
• Diabetic retinopathy
• Chronic glaucoma
Slow loss of sight (common)
• Corneal abrasion
• Corneal infection
• Anterior uveitis = “iritis”
• Optic neuritis
• Acute glaucoma
Rapid loss of sight (less common)
• Corneal swelling
• Corneal scarring
• Compressive optic neuropathy
• Medication or drug toxicity
Slow loss of sight (less common)
• Central retina no longer works properly
• Affects central vision
• VA
• Distortion “wet”
• Causes problems with:-
• Reading
• Recognising faces
• Seeing road signs when driving
Age-related macular degeneration = AMD
• Old age “wear & tear”
• Accumulation of subretinal deposits = drusen
• Atrophy
Dry AMD
• Dry changes neovascularisation
• Leakage from new blood vessels
• Wet AMD vs Dry AMD
• More rapid vision loss
• Vision loss more profound
• Distortion more common
* Always consider wet AMD if new distortion
Wet AMD
• Proliferation of fibrous tissue on retinal surface
• Triggered by PVD or surgery
• Distortion of retinal surface
Epiretinal membrane
• Arteriole emboli travelling from carotid → eye
• Venous thrombus from localised arterial compression
• Ischaemia
• Leakage of fluid when venous blockage
* Rapid and often profound unilateral loss of vision
* Consider vascular cause when vision loss very rapid
Retinal vascular occlusions
• Artertitic
• Vasculitis occludes ciliary arteries
• Typically 70+ yrs, Sx of GCA and profound vision loss worse than 6/60
• New HA > scalp tenderness > polymyalgia > jaw claudication > systemic Sx
• When suspected order same day ESR + CRP
• Non-arteritic
• Systemic and ocular pre-disposition
• Typically mid-50s and significant, but not profound vision loss
Ischaemic optic neuropathy
• Bleed inside the eye
• Sequalae of proliferative diabetic retinopathy
• Retinal tear + Ocular tumours less common causes
• Sudden, painless loss of vision
• Mild = Increase in floaters/streaks and blurred vision
• Severe = Profound reduction in vision to perception of light
* Consider if sudden vision loss in diabetic with known DR
Vitreous haemorrhage
• Major risk factors = Myopia + Trauma
• Most symptoms related to triggering PVD
• Sudden increase in the number of floaters
• Flashes of light
• Dark shadow that starts at the edge of vision and extends centrally
• Impression of a veil or curtain over vision
Retinal detachment
• Suspect CVA/TIA when
• No history of migraines, or “different”
• Non-trivial cardiovascular risk factors
• Vision loss sudden over seconds, not minutes
• Associated neurological symptoms
• Check BP and refer to stroke clinic if unsure
Migraines + CVA/TIAs
• Mismatch between focusing power and length of eye
• Myopia
• Eye is relatively too long
• Hypermetropia
• Eye is relatively weak in power
• Astigmatism
• Non-rotational symmetry of the focussing power of the eye
Defocus
• Age-related stiffening of crystalline lens
• Inertia and reduced amplitude of accommodation
• Emmetropes
• Difficulty reading
• Myopes
• Difficulty reading when wearing distance spectacles
• Hypermetropes
• Difficulty reading and then later difficulty with distance
Presbyopia
• Clouding of the crystalline lens
• Reduced contrast
• Glare
• Reduced acuity
• Ghosting
Cataract
• Posterior capsular opacification
• Macular oedema
• Corneal decompensation
Cataract – complications of surgery
• Changes in the small blood vessels of the retina
• Leakage
Accumulation of leaked fluid in central retina
Diabetic maculopathy
• Blockage
Proliferative diabetic retinopathy
Vitreous haemorrhage and tractional retinal detachment
Diabetic retinopathy
• Damage to the retinal nerves as they leave the eye
• Main cause is raised intraocular pressure
• Usually asymptomatic
• May only affect one eye, or different parts of the two eyes
• Progress usually slow over several years
• Brain fills in gaps
Glaucoma
• Eye problems – 3 red flag Ps
• Poor vison - especially sudden loss or distortion
• Pain
• Photophobia
• Consider vascular or neurological disease
• Recognise limitations when not simple trauma
Recap
• Sudden loss of vision
• Pain
• Distortion
• Light sensitivity
• Red eye, especially in contact lens wearer
• New neurological Sx
• Sx suggestive of GCA
Red flags
• One or both eyes
• How quick - seconds/minutes - days – months
• How bad
• What activities is it making difficult
What to ask
• Pain, or annoying discomfort
• Are bright lights painful or significant glare
• Distortion
• Recent trauma/surgery
• New neurological Sx
• Sx suggestive of GCA
What to ask
• Consider demographics
• Consider general health, principally vascular health
• Is the eye red
• Visual acuity – RE & LE tested separately
What to examine
• Optional:
• Pupil reflexes – is constriction to light symmetrical
• Crude assessment of peripheral vision with confrontation
• Assessment of red reflex with the ophthalmoscope
• Ophthalmoscopy
• Blood pressure
What to examine
Reduced Vision
Dr Michael Johnson
PhD FCOptom DipOrth DipGlauc DipTp(IP)
Johnson & Furze Optometrists, Thornbury
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