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