What are the main blinding retinal conditions?
This list is not exhaustive but the top conditions which account for the majority of vision impairment and blindness in the UK include:
Wet age-related macular degeneration:
This condition starts with a sudden blurring of central vision and distortion which is painless and progressive. Abnormal blood vessels from the layer beneath the retina, choroid, damage the photoreceptors. This condition needs urgent attention to avoid irreversible loss of vision and is the commonest cause of blindness in the UK.
In diabetes very small blood vessels within the retina get damaged and leak fluid causing swelling of the retina, displacing the photoreceptors resulting in distortion. With advancing disease abnormal blood vessels can develop and bleed, causing floaters and vision loss. These symptoms require urgent attention to limit any damage. DR is the most common cause of blindness in the working population.
Retinal vein occlusion:
This condition refers to blockage of the main trunk or smaller contributories of the retinal veins that drain the blood from the retina. Vein occlusion can result in central blurring or loss of vision through fluid accumulation in the macula and sheer force of the blockage causing damage to the photoreceptors. In branch vein occlusions, if the central part of the retina is spared, vision blurring occurs just off centre and can be peripheral.
Myopic choroidal neovascularisation:
In patients with high degrees of short-sightedness, the eyeball and the retina are stretched over an abnormally large area. As a result the barrier separating the retina from the abnormal blood vessels beneath in the choroid becomes susceptible to damage. Once abnormal blood vessels grow into the retina, the photoreceptors can get damaged and the patient develops symptoms of vision loss and distortion in their central vision.