The retina is the light-sensitive layer at the back of the eye, responsible for transmitting visual information to the brain. A threat to its integrity, such as a detachment, can cause severe vision impairment or even blindness.
Hence, understanding retinal detachment is crucial in preventing this vision-threatening condition. Medical Channel Asia invites Dr Jacob Cheng, Director of Retina Services of Eagle Eye Centre and visiting consultant at the Singapore National Eye Centre (SNEC), to explain this condition in further detail.
What is the retina?
The retina is the light-sensitive membrane that lines the inner layer of the eyeball much like the film in a camera. Firstly, light from objects enters the eye and is focused onto this retina. Secondly, the retina transmits visual signals to the brain via the optic nerve and that allows us to process the images. The central retina (called the ‘macula’) is responsible for clear central vision and colour vision, whilst the peripheral retina is responsible for the peripheral navigational vision and night vision.
What is a retinal hole/ tear?
The jelly-like substance known as the vitreous fills the eye, is in contact with the retina, and is responsible for the shape of our eyeball. With age, the vitreous gel liquefies and shrinks in size causing it to separate from the retina. This separation may pull on the retina causing a retinal tear.
Furthermore, the danger of a retinal tear or hole lies in its risk of progression to a retinal detachment, which can cause blindness if left untreated.
What is a retinal detachment?
Retinal detachment occurs when fluid enters through a retinal hole or tear and accumulates behind the retina, separating it from its underlying tissues. This is an emergency which requires immediate medical attention to preserve vision. The separation of the retina from its underlying tissue results in a lack of oxygen and nutrients to the light-sensitive cells of the retina known as the photoreceptors. Therefore, if left untreated, damage to the photoreceptors will result in permanent loss of vision. Additionally, bleeding may occure if blood vessels are involved in the retinal tear.
What are the most common symptoms of retinal detachment that people should be aware of?
- This appears as spots or strands of black or semi-transparent ‘debris’ in the vision that moves with eye movements.
- It is often described as a cobweb or fly.
- This appears as brief lighting streaks usually in the periphery.
- It occurs due to vitreous pulling on the retina and may precede floaters.
- It is induced by eye movements and is best seen under dim illumination.
- Unlike floaters, the location of the flashes is unrelated to the location of the break.
- This is usually described as a falling curtain or veil that obscures part of the vision.
- The area of blocked vision corresponds to the location of the retinal detachment.
- This occurs when the detachment progresses to involve the central vision (or ‘macula’).
- This may be associated with distorted vision in the early stages.
- Retinal breaks in the periphery may remain unnoticed until a detachment occurs.
How frequently do you encounter cases of retinal detachment?
In Singapore, experts estimate the prevalence of retinal detachment to be around 1 in 10,000 individuals per year.
Could you discuss the risk factors associated with retinal detachment?
The common risks for retinal tears and detachment are:
- Age > 50 years old
- Family or personal history of retinal detachment
- History of intraocular surgery
- History of trauma
- History of high myopia (> -6D)
- Peripheral retinal degeneration (e.g. Lattice degeneration)
- Retinal disease (e.g. diabetes)
- Retinal inflammation
Are certain populations or age groups more at risk for developing retinal detachment?
In general, individuals over the age of 50 are at a higher risk as the vitreous gel tends to liquefy and shrinks with age. This separation increases the likelihood of retinal tears and hence retinal detachment.
How is retinal detachment diagnosed? What does the examination process look like?
Diagnosing retinal detachment requires a comprehensive eye examination performed by an ophthalmologist. This includes the visual acuity check and a dilated eye examination. Doctors can use ultrasound and photos to assist in the diagnosis and documentation.
What are the treatments available?
Treatment options all involve reattaching the detached retina to stabilize and prevent the worsening of vision. However, treatment does not always result in pre-detachment vision and prognosis depends on whether the macula is involved, and the duration from detachment to treatment.
Vitrectomy is a surgical procedure to remove the vitreous gel that caused traction on the retina. Firstly, the surgeon inserts fine instruments into the eye to remove the gel and remove scar tissue. Subsequently, the surgeon flattens the detached retina and repairs tears and holes in the retina.
Sclera buckling involves placing a silicone sponge or plastic placed outside the globe at the site of the retinal detachment. Thereafter, the material is sewn to the eye and is usually left in place permanently to indent (“buckle”) the globe to bring it closer to the detached retina. The buckling effect on the globe relieves the traction (“pull”) on the retina.
Laser therapy or cryotherapy is done to create a scar around a retinal hole and tear, to prevent it from enlarging and also prevent fluid from leaking in. Doctors can perform this procedure as an outpatient procedure (in the absence of retinal detachment), or as part of retinal reattachment surgery.
About Dr Cheng
Dr Jacob Cheng is the Director of Retina Services of Eagle Eye Centre and visiting consultant at the Singapore National Eye Centre (SNEC). He is a Consultant Surgeon in Cataract and Comprehensive Ophthalmology and subspecialises in the field of Vitreoretinal Diseases. He is involved in many pioneering research projects in drugs and in collaboration with many international institutions for research. to explain the condition. Dr Cheng is also an adjunct research scientist with the Singapore Eye Research Institute (SERI), a clinical teacher with the National University of Singapore (NUS) and a part-time consultant at the Singapore National Eye Centre (SNEC).