[5] Age-Related Macular Degeneration Flashcards
What does the term age-related macular degeneration (AMD) refer to?
Ageing changes that occur in the central area of the retina in people aged 55 years or older
What needs to be true of the changes in the central area of the retina to be classified as AMD?
Must not have any other obvious precipitating cause
What kind of disease is AMD?
Progressive, chronic disease of the central retina
Why is AMD important?
It is a leading cause of vision loss worldwide
What is AMD characterised by?
Appearance of drusen in the macula
What is the appearance of drusen in the macula accompanied by in wet AMD?
Choroidal neovascularisation
What is the appearance of drusen in the macula accompanied by in dry AMD?
Geographic atrophy
In what respects do the forms of AMD differ?
In pathophysiology and progression
What are the characteristic lesions of dry AMD?
- Soft drusen
- Changes in pigmentation (hypopigmentation and/or hyperpigmentation) of the retinal pigment epithelium
Where does the drusen accumulate in dry AMD?
Between the retina and choroid
What does the accumulation of drusen between the retina and choroid in dry AMD cause?
Atrophy and scarring of the retina
What happens to the atrophy in AMD over time?
The atrophy becomes more extensive with time
Can dry AMD progress and cause vision loss without turning into the wet form?
Yes
What % of cases of AMD are the dry form?
90%
Describe the progression of dry AMD
Progression to visual loss is usually gradual, but eventually there is an area of partial or complete atrophy of the retinal pigment epithelium
Does the atrophy of the RPE in dry AMD involve the fovea?
May or may not
What chance to those with dry AMD have of developing wet AMD?
4-12% chance/year
What happens in wet AMD?
New blood vessels grow in from the choriocapillaris under the retina
In relation to the RPE, where to the blood vessels grow in wet AMD?
Spread under or over the RPE, or both
Describe the abnormal blood vessels in wet AMD
Fragile and easily leak
Describe the location of growth of blood vessels in wet AMD
They start off to the side of the retina and grow towards the centre, eventually growing under the macula
How long does the process of blood vessel growth take in wet AMD?
Can take from days to weeks
What are the consequences of abnormal vessel formation in wet AMD?
- Haemorrhage
- Scar formation
What % of cases of AMD are wet AMD?
10%
What % of cases of wet AMD are advanced?
60%
How quickly will wet AMD progress to cause severe visual impairment without treatment?
Approx 2 years
What is the end point of wet AMD?
Scar formation, known as disciform macular degeneration
What % of patients who have had wet AMD in one eye will develop it in their second eye within 5 years?
Approx 50%
What can the severity of AMD be classified?
- No AMD
- Early AMD
- Intermediate AMD
- Advanced AMD
What is classified as no AMD?
None or small drusen
What is classified as early AMD?
Multiple small or a few intermediate drusen, with or without abnormalities of the retinal pigmented membrane
What is classified as intermediate AMD?
Extensive intermediate or 1+ large drusen, with or without GA not involving the fovea
What is classified as advanced AMD?
GA involving the fovea, with or without any features of wet AMD
What is the result of features of wet AMD be classified as advanced?
All cases of wet AMD are advanced at presentation
What causes AMD?
AMD is a multifactorial disease, with both environmental and genetic components playing a role in its development, however the specific causes are not known
What theories have been proposed regarding the cause of AMD?
- Oxidative stress
- Mitochondrial dysfunction
- Inflammatory processes
What are the risk factors for AMD?
- Increasing age
- Smoking
- Family history
- Cardiovascular risk factors (for wet AMD)
- Light coloured eyes
- Diets high in fat, cholesterol, and high glycaemic index foods
- Obesity
- Ethnicity
What is smoking a risk factor for in AMD?
New-onset and progression
What ethnicity is AMD most common in?
Caucasians
What does AMD cause?
Painless deterioration of central vision
How might asymptomatic AMD be identified?
Retinal signs may be detected incidentally during a routine eye test
What are the general symptoms of AMD?
- Reduction in visual acuity
- Loss of or decreased contrast sensitivity
- Size or colour of objects appearing different with each eye
- Abnormal dark adaptation
- Photopsia
- Light glare
- Visual hallucinations
What are the more specific symptoms of dry AMD?
- Gradual visual deterioration
- Potentially loss of central vision
How does gradual visual deterioration present in dry AMD?
Difficulty reading with small to large print over time
When can dry AMD cause deterioration of central vision?
When there is bilateral geographic atrophy of the fovea
What are the more specific symptoms of wet AMD?
- Central vision blurring and distortion
- Potentially rapid visual deterioration
What is the main identifying complaint of central blurring and distortion in patients with wet AMD?
Like what will the patient tell you they’re experiencing that makes you think ‘oh this is wet AMD’
Straight lines appear crooked or wavy
How can sudden visual deterioration present in wet AMD?
Suddenly unable to read, drive, or see fine detail
When may rapid visual deterioration progress to sudden visual loss in wet AMD?
If there is a bleed
What might sudden visual loss due to a bleed in wet AMD be preceded by?
A shower of floaters
What can visual examination show in AMD?
- Normal or decreased acuity
- Distortion of the Amsler grid
What may be seen on examination of the fundus in AMD?
- Drusen in the macular area
- Sharply demarcated areas of hypopigmentation or hyperpigmentation of the peripheral retina
- Well demarcated red patches (in wet AMD)
What are drusen?
Discrete yellow deposits
What do the red patches on the fundus in wet AMD represent?
Intraretinal, subretinal or sub-RPE hameorrhage or fluid
What may be seen on fundus examination in late AMD?
A macular scar, appearing as a thick yellow patch over the macular area
What is the aim of secondary care investigations in AMD?
Confirm the diagnosis, assess the extent of the disease and possibility of successful intervention, and measure progression over time
What investigations may be used in AMD?
- Slit-lamp biomicroscopy
- Colour fundus photography
- Fluorescein angiography
- OCT
What can be seen on slit-lamp biomicroscopy in AMD?
- Drusden
- Pigmentary changes
- Exudate
- Haemorrhages
- Atrophic changes of the macula
What is the purpose of colour fundus photography in AMD?
To record the appearance of the retina
When is Fluorescein angiography required in suspected AMD?
When it is suspected wet AMD to confirm and assess lesion
How is Fluorescein angiography performed?
Fluorescein dye is injected IV and photographs of the retina are taken serially to detect abnormal vasculature or leakage
What is OCT?
Ocular coherence tomography
What can cause painless loss of vision?
- Refractive errors
- Cataracts
- Some corneal diseases
- Posterior vitreous or retinal detachment
- Retinal artery or vein occlusion
- Cerebrovascular disease
- Some drugs
- Tumours
- Papilloedema
- Primary open-angle glaucoma
- Optic atrophy
What cerebrovascular disease can cause painless visual loss?
- Amaurosis fugal
- TIA or stroke
What drugs can cause painless visual loss?
- Methanol
- Chloroquine
- Isoniazid
- Isotretinoin
- Tetracycline
- Ethambutol
What tumours can cause painless visual loss?
- Pituitary tumour
- CNS tumour
What conditions can cause similar retinal signs to AMD?
- Diabetic maculopathy
- Macular dystrophy
- Rare Inflammatory syndromes causing choroidal neovascularisation
- Macular telangiectasis
In what time frame should patients with suspected AMD be referred?
Ideally within 1 week
When is urgent referral for AMD particularly important?
When the patients has sudden distortion or rapid-onset visual loss as these suggest wet AMD
What is the main management for dry AMD?
Lifestyle adjustments in an attempt to slow progression
What does dry AMD management consist of?
- Counselling
- Smoking cessation
- Visual rehabilitation
- Nutritional supplements
- Management of co-existing visual impairments
What does visual rehabilitation for AMD revolve around?
Maximising any remaining visual function and assisting the person to maintain an independent life for as long as possible
What can visual rehabilitation for AMD involve?
- Refraction check
- Low visual aid clinic
What can be provided by a low visual aid clinic for AMD?
- Provision and training on use of optical aids e.g. magnifiers
- Advice on lighting, tactile aids, electronic aids and other non-optical aids
What legal responsibility do people with AMD have?
To ensure their eyesight is good enough to drive and if not contact the DVLA
What is the current standard for treating wet AMD?
Intravitreal injections of anti-vascular endothelial growth factor agents
How can anti-VEGF agents be administered in wet AMD?
In theatre or in a designated treatment ‘clean room’
What anti-VEGF agents can be use in AMD?
- Ranibizumab
- Bevacizumab
How long are anti-VEGF treatments used for?
Monthly for 3 months and then at variable times after depending on response
What proportion of patients will retain their current visual level in treatment of wet AMD?
Most
What percentage of patients with wet AMD will not respond to anti-VEGF treatment?
10%
What are the complications of intravitreal injections?
- Hypersensitivity reaction
- Endophthalmitis
- Retinal detachment
- Severe uncontrolled uveitis
- Ongoing periocular infections
- Thromboembolic phenomena
- Traumatic cataract
What older treatments can be used for wet AMD if anti-VEGF is not advisable?
- Laser photocoagulation
- Photodynamic therapy with verteporfin
- Macular translocation
What are the potential complications of visual impairment?
- Depression
- Visual hallucinations (Charles Bonnet syndrome)
- Falls and fractures
- Limitations in mobility, ADLs and physical performance
- Reduced QoL
What are the potential complications of wet AMD?
- Serous retinal detachment
- Haemorrhage
