Retinal disorders
Retinal diseases are a broad range of eye diseases that affect any part of the retina, a thin layer of tissue at the back of the eye. The retina is involved in sending information to the brain, enabling sight. While some are hereditary, they can also be related to ageing, diabetes or other diseases.
Diabetic retinopathy & Diabetic macular edema
Diabetic retinopathy (DR) occurs when damage to the blood vessels causes blood and/or fluid to leak into the retina, leading to swelling, as well as blockage of blood supply to some areas of the retina. At first, DR may cause no, or only mild, eyesight problems, so treatment is often delayed until complications occur, such as development of diabetic macular edema or a vitreous hemorrhage, which leads to vision loss.
Diabetic Macular Edema (DME) is a complication of DR, which happens when the damaged blood vessels leak into, and cause swelling in, the macula. The macula is an area of the retina responsible for the sharp vision needed for reading and driving. DME can cause blurred vision, loss of contrast sensitivity (the ability to distinguish between shades of light and dark) and patches of vision loss, which may appear as small black dots or lines ‘floating’ across the front of the eye.
DME is often treated with injections in the eye that block the actions of a specific protein, vascular endothelial growth factor (VEGF), which increases leakiness in retinal blood vessels.
Retinal Vein Occlusion
A Retinal vein occlusion (RVO) is a blockage of the blood supply to the retina, which ‘starves’ the retina of oxygen so that it is unable to send visual information to the brain. When a retinal vein is blocked, it can no longer drain blood from the retina, which leads to haemorrhages and fluid leakage into the retina, causing swelling.
Symptoms of RVO include sudden, painless blurring or vision loss affecting central vision and/or part of the visual field in one eye.
RVO typically affects people over 50, becoming more common with increasing age. Those with a history of high blood pressure, diabetes and atherosclerosis (build-up of fatty plaques in arteries) are at increased risk of developing RVO.
Neovascular Age-Related Macular Degeneration
Age-related macular degeneration (AMD) affects the macula, the part of the retina that provides sharp, central vision needed for activities like reading.
Neovascular (also known as “wet”) AMD (nAMD) is an advanced form of the disease, which develops when new and abnormal blood vessels grow uncontrollably under the macula, causing swelling, bleeding and/or fibrosis.
In addition to age, other risk factors include smoking, race, family history and genetics.
Symptoms of nAMD include sudden blurred vision, difficulty seeing at distance or doing detailed work, blind spots developing in the line of sight, colours becoming hard to distinguish, edges and straight lines appearing wavy.
Anti-VEGF injections are also used to treat nAMD to prevent the uncontrolled growth of new blood vessels, mostly under the retina. However, this treatment may require monthly eye injections during prolonged periods of time, which for some patients can lead to problems with adherence, under-treatment and subsequent declining vision long-term. Other treatment options include photodynamic therapy, a laser treatment of select areas of the retina, designed to target and destroy the abnormal blood vessels
Myopic Choroidal Neovascularization
Myopic choroidal neovascularisation (mCNV) is a common, vision-threatening complication of severe short-sightedness (also known as pathological myopia). As a result of myopia, new abnormal blood vessels can grow underneath the retina, leaking blood and/or fluid.
mCNV can cause irreversible central vision loss. Other symptoms include blurred vision, distorted view of objects and lines, and difficulty distinguishing between colours.
Geographic Atrophy
Geographic atrophy (GA) is responsible for 10-20% of blindness in Age related Macular Degenration (AMD). GA is an advanced form of AMD, where the light-sensitive cells in the retina begin to degenerate and die, creating blind spots in the central field of vision. GA is progressive and irreversible, and there are currently no available treatments for this condition. The most consistent risk factors for GA are age, family history and smoking.
Retinal Detachment
Retinal detachment is a disorder of the eye in which the retina separates from the layer underneath. Symptoms include an increase in the number of floaters, flashes of light, and worsening of the outer part of the visual field. This may be described as a curtain over part of the field of vision. Without treatment permanent loss of vision may occur.
The mechanism most commonly involves a break in the retina that then allows the fluid in the eye to get behind the retina.[1] A break in the retina can occur from a posterior vitreous detachment, injury to the eye, or inflammation of the eye.
In those with a retinal tear, efforts to prevent it becoming a detachment include cryotherapy using a cold probe or photocoagulation using a laser.Treatment of retinal detachment should be carried out in a timely manner. This may include scleral buckling where a silicone band is sutured to the outside of the eye, pneumatic retinopexy where gas is injected into the eye, or vitrectomy where the vitreous is partly removed and replaced with either gas or oil.
Peripheral Retinal Degenerations
Retinal degenerations are common lesions involving the peripheral retina but most of them are clinically insignificant. Lattice degeneration, degenerative retinoschisis, cystic retinal tufts, and very rarely zonular traction tufts can result in rhegmatogenous retinal detachment. Therefore, these lesions have been considered for prophylactic treatment. Most of the peripheral retinal degenerations may not require treatment except in rare, high-risk situations.