Drusen are toxic waste under the light-sensitive layer at the back of the eye called the retina. When they are seen in the central part of retina they can be a precursor to an eye disease called macular degeneration, which is the leading cause of blindness in an age bracket greater than 50 years of age. Make sure you visit our macular degeneration page.
They are made up mainly of protein and lipids, which come from underlying tissues. They are believed to be the product of the eye’s failure to eliminate waste products from cells within the eye.
Types of drusen
- Hard drusen are small and distinct from one another. This type of drusen may not cause vision problems for a long time, if at all.
- Soft drusen are large and cluster closer together. Their edges are not as clearly defined as hard drusen. This soft type of drusen is a sign of age-related macular degeneration (ARMD). It is not fully understood if drusen are a cause or an effect of ARMD, but when they are seen in the macular area they definitely are associated, so should be monitored carefully.
Drusen are often found in people over 60. While the presence of a few small drusen is normal with advancing age, the presence of many, larger drusen is usually indicative of AMD.
Drusen can also be present on the optic nerve (or optic disc). They contain calcium as well as protein and lipid and are found in any age-group, not just older people. Optic disc drusen usually do not affect vision, but some patients with these drusen may lose peripheral (side) vision.
Symptoms of Drusen
Most people will have no symptoms, but in cases of many, soft drusen, where ARMD is present, there may be blurry vision, especially central vision.
• Family history of ARMD
• Caucasian race
• Abnormal cholesterol levels
Optic nerve drusen are also more prevalent for those with a family history or of Caucasian descent.
Drusen are diagnosed during a routine eye examination. Your optometrist may dilate your pupils to see the whole retina and if drusen are found, you may also do an Amsler Grid test which looks for distortion in your central vision.
Optic disc drusen may be diagnosed during a routine eye examination and may sometimes need to be confirmed with an OCT (optical coherence tomography) which gives a 3D picture of the optic nerve so the underlying layers can be seen.
Hard drusen require no treatment but may need to be monitored regularly to ensure they don’t develop into soft drusen. Soft drusen are treated as part of the overall management of ARMD. This may include intra-vitreal injections called anti VEGF, which can stabilise and even improve vision in ARMD patients.
Because drusen are associated with macular degeneration it is important to consider other risk factors and recommend appropriate lifestyle changes. These can be:
- Stop smoking
- Protect against excessive blue light
- Supplement with Lutein
There is no treatment for optic disc drusen. Monitoring for progressive visual field defects is important and it is thought that by decreasing the intraocular pressure might be of some benefit.