Retinal detachment is an ophthalmic emergency that requires an urgent assessment by an ophthalmologist and in most cases urgent surgery to prevent permanent sight loss. There are 3 types of retinal detachment: rhegmatogeneous (break related), tractional or exudative, each with different causes and treatment. We will discuss the rhegmatogeneous subtype which is the commonest cause of a retinal detachment.
What is a retinal detachment?
Retina is the tissue layer of the eye that helps you see. It processes light rays into neural signals that are sent to the brain for interpretation. When there is a defect caused by a break or hole in the retina, fluid passes through the defect and detaches the retina from its attachments to the wall of the eye, hence the term retinal detachment. It is a relatively common (1 in 10,000 per year) condition with certain groups of people at higher risk. These include people who are short sighted (myopia), history of previous eye surgery, injury or family history.
What are the symptoms of retinal detachment?
Retinal detachment in most cases develop suddenly and patients generally present with some of the following complaints:
- The sudden appearance of many floaters — tiny specks that seem to drift through your field of vision
- Flashes of light in one or both eyes (photopsia)
- A curtain-like shadow over your visual field
Occasionally, retinal detachments can be asymptomatic and found incidentally during routine eye examinations. If left untreated, it normally leads to total loss of vision in the affected eye.
How is it treated?
Retinal detachments are treated surgically with either one of two techniques; internal or external. The internal approach is by vitrectomy, a ‘keyhole’ surgery done mostly under local anaesthetic (or occasionally general anaesthesia) and involves removing the vitreous (jelly substance in the eye), finding the break in the retina, flattening the retina, treating the break with either laser or cryotherapy (freezing treatment) and inserting an expansile intraocular gas that acts as a tamponade on the break whilst it heals. It is analogous to ‘spot-welding’ the tear close, so that when the gas dissolves in usually 4 to 8 weeks, the tear is sealed and the detachment repaired. Occasionally, silicone oil is used in place of gas and will require another surgery (usually in 3 to 4 months) to remove it. If gas is used, patients will have blurred vision in the affected eye until the gas dissolves. They will also not be able to fly or go on high altitude for the duration.
The other approach for retinal detachment is the external approach, placing a silicone band (buckle) on the wall of the eye (sclera) after treating it with cryotherapy (freezing treatment). This creates an indent in the wall of the eye, helping the detachment to settle. It is suitable for certain types of retinal detachments only and is best done under general anaesthetic.
The choice of techniques, tamponade agents and anaesthetic agent (local or general anaesthesia) will be discussed with you in detail during your initial consultation.
How urgent is treatment needed?
The urgency of surgery is dependent on a few factors, primarily the involvement of the central retina (macula) in the detachment. If the macula is not detached, then prompt surgery (ideally within 24 hours) may prevent significant visual loss.
However, if the macula is detached at the time of presentation, then surgery can be undertaken within a few days to ensure restoration of vision to the eye. However, the final visual gain is generally limited and variable with some patients reporting no improvement and some over 90%. It is likely that vision will not be at the level it may have been prior to the detachment developing. Nevertheless, the prognosis without surgery is very grim, with a majority of patients going blind in the untreated eye with time and so surgery is highly recommended in most cases.
How successful is surgery?
Success rates for retinal detachment repair with one surgery is about 80-90% meaning that 1 or 2 out of 10 people having surgery will require further procedure(s) to reattach their retina. These cases tend to be in those who present late and where the detachment has been present for a long time with formation of scar tissues. For the final level of vision, the most important factor is whether the central retina (macula) is affected (detached) prior to surgery.
Figure: Widefield image of a patient with retinal detachment (image on your left) and after successful treatment with a cryobuckle (external approach) surgery (image to your right).