Diagnosis

• Due to varying symptoms of AMD, examination of each eye should be done carefully (with the other eye covered) by measuring visual acuity and by detecting subtle areas of distortion using Amsler grid (1)
  • visual acuity may be inside the normal range in patients with drusen and mild pigmentary changes alone. In late AMD the visual acuity is decreased in the affected eye (2)
  • areas of central visual distortion and scotoma may be described by patients as breaks, waviness, or missing portions of the lines of an Amsler grid (1)
    
    
• Fundal examination may be done using
  • stereoscopic viewing method (slit-lamp biomicroscopy)
    • preferred method
    • drusen, pigmentary, exudative, haemorrhagic, or atrophic changes affecting the macula may be detected (2)
    • non-stereoscopic examination (direct ophthalmoscopy or fundal photography) (2)
      
      
• Additional tests:
  • Fluorescein angiography - to identify the presence and nature of neovascular AMD (2)
  • indocyanine green angiography (3)
  • Optical coherence tomography - generates cross-sectional images through the retina, RPE and choroids and is useful in the diagnosis (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:

• 1. Jager RD, Mieler WF, Miller JW. Age-related macular degeneration. N Engl J Med. 2008;358(24):2606-17
• 2. Cook HL, Patel PJ, Tufail A. Age-related macular degeneration: diagnosis and management. Br Med Bull. 2008;85:127-49
• 3. Chopdar A, Chakravarthy U, Verma D. Age related macular degeneration. BMJ. 2003;326(7387):485-8