The choroid is a vascular layer – that’s to say it’s made up of blood vessels and capillaries – that lies between the white part of the eye, the sclera, and the internal retinal layer.
If the choroid cannot supply oxygen and nutrients through the blood to those layers then obviously the eye will begin to suffer – the sclera will begin to dry out, become inflamed and form ulcers, whilst the retina will not be able to process the light that it receives into messages for the brain.
All in all, the choroid is an essential part of the efficient workings of the eye.
The choroid can be subject to a variety of diseases and disorders.
Firstly, what is the difference between a disease and a disorder of the eye?
Really the two terms are sort of interchangeable and are used by eye specialists more in respect of the feelings of a patient than anything else.
Rather than suffer from a disease it’s perhaps less denigrating to suffer from a disorder! This may be since connotations of disease raise questions regarding cleanliness and behaviour.
In the context of the English language of course there is somewhat of a difference in perceived usage:
• Disease – thought of something you catch randomly from someone or something, such as bacterial or viral conjunctivitis.
• Disorder – something that is wrong with the eyes such as near sightedness or colour blindness. Disorder infers perhaps that of something being merely a chance happening.
Another term often used in place of both disease and disorder is “condition” – using the term “condition” really takes the stigma out of them both. Suffering from an infectious eye condition sounds much better than disease don’t you think?
The word condition should be used in its correct context of comparison: “the sclera is in good condition” or “in poor condition”.
Of course the actual word used – whether disease, disorder or condition – isn’t going to alter neither the symptoms nor the treatment one bit!
The range of diseases and disorders in the choroid include both inflammatory diseases and disorders
• Chorioretinitis – (sometimes called choroid retinitis) – an inflammation of both the choroid AND the retina. It can also be classified according to causal diseases such as syphilis and tuberculosis.
• Choroiditis – an inflammation accompanied by swelling, where only the choroid alone (not the retina) is affected. The infection can be found in children and adults with immune deficiency.
• Choroideremia – inherited my males, the choroid degenerates initiating night blindness and loss of peripheral vision, and ultimately total loss of vision. Gene therapy research and pre-clinical trials offer the most promising future treatment
• Choroidal haemorrhage – can occur due to complications from eye surgery, however the event is rare and remedial steps can be taken
• Choroidal detachment – this can occur if the very minute space between the choroid and the sclera fills with fluid. As the area fills so the choroid becomes detached and cannot provide the sclera with the oxygen and nutrition in requires.
The choroid is an essential part of the eye, and it is obvious that any of the above diseases and disorders can have a serious effect on eye function and other parts of the eye if not detected and treated.