Patients with early age related macular degeneration is often asymptomatic and visual loss is generally mild (1). The following symptoms may be the presenting feature in patients with AMD
- visual distortions for example, straight lines appearing bent (metamorphopsia) (2).
- blurring or a black or grey patch in their central vision (scotoma) (4)
- reading gradually becomes more difficult (initially the smaller sizes of print which later develops into difficulty in reading larger print and/or words) (3) and central vision is lost with visual acuity often less than 6/60.
- decreased contrast sensitivity
- problems in adapting from bright to dim lighting (abnormal dark adaptation) (1)
- size or colour of objects may appear to differ with each eye
- showers of floaters or clouding of entire visual field (due to vitreous haemorrhage)
- flickering or flashing lights – photopsias (2)
- visual hallucinations (Charles Bonnet syndrome) seen in late AMD (4)
- peripheral vision is undisturbed.
It is important for primary care physicians to identify these symptoms (specially in patients who are at a risk of developing AMD) as some patients might consider them to be a part of the ageing process or due to development of cataracts and ignore them initially (2)
Changes in the macular architecture are visible with the ophthalmoscope, but often only once the pupil has been dilated. Two broad clinical types of senile macular degeneration are recognised:
- non-exudative / dry - characterised by drusen - variably sized, yellowish round spots in Bruch's membrane which are scattered throughout the macula and posterior pole. They are refractile on account of the overlying retinal pigment epithelium. Additionally, dark clumps may be seen in the pigment epithelium with intervening areas of choroidal exposure due to pigment atrophy
- exudative / wet - characterised by choroidal neovascularisation and leakage of serous fluid or blood through degenerative breaks in Bruch's membrane. Retinal pigment epithelial detachment may occur which may undergo fibrous metaplasia and organisation to form an elevated sub-retinal mass or disciform scar. Colloid bodies are invariably present
Drug - induced degeneration is characterised by a pigmentary maculopathy with a "bulls eye" appearance.
Reference: