When you are trying to understand all about the eye and its diseases, including disorders of vision, you will often come across the word retina. This article will help you understand what the functions of retina are, and why it is important for your vision.
What is the retina in the eye?
The eye functions like a very sophisticated camera. The cornea and lens of the eye focus the light entering the eye on the innermost layer of the eye, called the retina. The retina is the light-sensitive layer of tissue that lines the inside of the eye and acts like the film in the camera, capturing images.
The images formed on the retina are transmitted via the optic nerve to the brain, where they are interpreted in the occipital cortex.
What are the common disorders of the retina in the eye?
The most common disorders of the retina in the eye include the following:
Age related macular degeneration: This is an age related change that occurs in the macula, the central, most light sensitive part of the retina responsible for visualising precise and fine details. In AMD, the macula gets affected, due to either atrophy or thinning, or due to formation of new blood vessels that bleed or leak proteins and fluid. This causes distortion of vision and subsequent loss of vision too.
Diabetic retinopathy: This is a disease of the retina because of diabetes. In this the blood vessels of the retina become fragile, and leak fluid and blood. Diabetic retinopathy may also be associated with the formation of new blood vessels which can cause loss of vision by bleeding or pulling the retina away from the underlying layers of the eye.
Retinal detachment:When the retina is lifted or pulled away from its normal position, vision gets affected. This can be due to small areas of the retina that are torn, or thinned to form retinal breaks or holes. This is called rhematogenous retinal detachment. In case the retina is pulled away from the underlying structures due to scarring of fibrous tissue and blood vessels, it is called a tractional retinal detachment.
Retinitis pigmentosa: Retinitis Pigmentosa is a genetic disorder of the retina and causes the loss of night vision and peripheral vision in the early stages, and a complete loss of vision in the later years.
Retinoblastoma: Retinoblastoma is a rare cancer that develops from the immature cells of the retina. It is the most common primary malignant intraocular cancer in children, and it is almost exclusively found in young children presents as a white discoloration of the pupil of the eye.
What are the common tests for the retina in the eye?
To see your details of the retina, in addition to a routine eye check-up, your doctor may ask for the following tests:
Dilated ophthalmoscopy (direct or indirect, or binocular slit lamp assessment with 78D, or 90 D lens): These tests allow your doctor to see the structural details of the retina.
Fundus flourescien angiography, FFA: In this the surgeon injects a dye in your forearm which travels to the blood vessels of the eye. The surgeon can then image your retina to see the blood vessels of the retina in great detail.
Optical Coherence Tomography, OCT: the OCT of the macula enables the surgeon to see the structural details of the macula and helps the doctor to arrive at a diagnosis for several diseases of the macula and retina.
Ultrasound A and B scan: Ultrasound of the eye may be ordered by your surgeon in order to detect certain diseases like vitreous haemorrhages, retinal and choroidal detachments, as well as tumours.
Other imaging modalities like MRI, CT and X-ray of the orbits may also be required for a complete diagnosis, in certain rare cases of retinal disorders.