Question

What is the constituency of Choroid?

Answer 1

Hint: The Choroid is the part of the eye. It is the middle layer of tissues which is present in the Retina. The main function of choroid is it keeps the retina healthy and functioning.

Complete answer:
The Choroid is the layer of tissues which is made up of blood vessels. It supplies oxygen and nutrients to the outer part of the retina. The choroid is made up of melanocytes, immunocompetent cells, fibroblasts, connective tissue, collagens etc.
The location of the choroid is represented in the figure below.

Choroid comprises of:
• Bruch’s membrane: It is the membrane which is present on the external surface of the retinal pigment epithelium which forms the basement membrane along with the choriocapillaris.
• In between the two layers of the basement membrane is present the collagenous and elastic layer.
Some localised thickening known as drusen is seen in this membrane.
• Choriocapillaris is the network of capillaries which supplies oxygen and essential nutrients to the retinal pigment epithelium and the outer retina.
• The pigmented cells are scattered in the choroid. They are dark coloured melanin pigments which help in absorbing light and thus limiting reflection.
• The melanin also prevents the blood vessels in the choroid vessels from light toxicity.

Note-
• It is dark brown in colour, prevents reflection in the eye and reduces blurred vision. The choroidal circulation accounts for around 85% of the oxygen circulation in the eye.
• It also helps in maintaining the temperature and volume of the eye. The damage in the choroid can lead to haemorrhage and also serous macular detachment.