Kirsti Takki has written:

'Gyrate atrophy of the choroid and retina associated with hyperornithinaemia'

Progressive Retina Atrophy is a dominant genetic disorder.

This is the middle layer of the eyeball and it is composed of the choroid, ciliary body and iris.

The choroid is a layer of the eye deep to the retina and superficial to the sclera. It provides oxygen and nutrients to the retina through its extensive network of capillaries. The retina itself does not have a huge vascular supply, because the vessels would interfere with the formation of the image in the eye. This is why the choroid is necessary.

The choroid is also very heavily pigmented due to an abundance of melanin. This increased pigment allows the choroid to absorb excess light and minimize reflections within the eye.

The choroid along with the iris and ciliary body make up what is known as the uveal tract.

Sclera, choroid, and the retina.