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Flashcards in Ophthalmology Deck (2)
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Define the term exudate

A liquid or semisolid which has been discharged through the tissues to the surface or into a cavity. Exudates in the retina are opacities that result from the escape of plasma and white blood cells from defective blood vessels. They usually look greyish-white or yellowish and are circular or ovoid in shape. They are sometimes classified into three groups according to size: (1) punctate hard exudates, which often tend to coalesce. They are found in diabetic retinopathy, Coats' disease, etc.; (2) exudates of moderate size, such as 'cotton-wool or soft exudates' as, for example, in branch/central retinal vein occlusion, hypertensive retinopathy, etc. These 'exudates' have ill-defined margins and are actually areas of ischaemia containing cytoid bodies, unlike hard exudates which are generally lipid deposits; (3) larger exudates, as found in the severe forms of retinopathy.


What are drusen

Drusen are deposits that form under the retina. They look like yellow spots in the retina and their presence is often a precursor to more serious macular degeneration. The retina is located in the back of the eye and functions like film in a camera. The retinal photoreceptors (rods and cones) are metabolically active and require a rich blood supply to function properly. Drusen are accumulations of “debris” that form under the retina, blocking the transfer of nutrients and oxygen between the retina and the supporting choroid (a bed of blood vessels that nourish the retina) underneath. This blockage of nutrition transport causes the retina to slowly atrophy and can lead to significant visual dysfunction over time. This process is called macular degeneration. “Macular drusen” should not be confused with optic nerve drusen which are calcium crystals in the optic disk that rarely cause visual problems.