Floaters
The centre of the eye is filled with a vitreous jelly that is a mixture of water and protein; early in life the jelly is perfectly clear but over time some of the protein comes out of solution and is seen as condensations of protein, or floaters, that move within the field of vision. Most floaters accumulate as part of the normal ageing process of the eye. They can also develop in association with retinal tears or inflammation within the eye, and so a prompt ophthalmic examination is required if there is a sudden increase in the number of floaters.
What will happen if I don't have treatment for floaters?
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Floaters ordinarily remain long-term. For many people they become less noticeable and troublesome with time. This is not the case for everyone though. In addition, they usually remain visible in certain lighting conditions, eg when there is a bright background. Most people with floaters can still read small text and have good vision, albeit with the intermittent disturbances caused by the floaters; as long as there is not an underlying cause for the floaters then the vision is not under threat from the floaters.
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What are the treatment options?
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Laser to break the floaters into smaller bits is performed in a small number of centres; it is of limited effectiveness. Vitrectomy surgery, to remove the vitreous jelly and floaters within it, is a much more effective, and commonly performed procedure. Both types of treatment are associated with rare risks.
On the day of surgery
Vitrectomy surgeries are commonly performed under either local or general anaesthetic. If your surgery is planned under local anaesthetic then you can eat and drink as normal prior to surgery, and should take regular medications as normal. For a general anaesthetic you will be given instructions specific to you, and your medical history, prior the surgery. Even with a general anaesthetic it is anticipated to be day case surgery. Immediately prior to the surgery eye drops are used to dilate your pupil. During the surgery you will be asked to lie flat on your back. The skin around the eye will be thoroughly cleaned (ordinarily with iodine) and a sterile drape applied over the eye to be operated on. This is lifted up over your nose and mouth. Once some anaesthetic has been given, a small clip is used to hold the eyelid open. The floaters are removed through 3 small (1-2 mm) incisions in the white of the eye. The retina is then checked and if there are any areas that predispose you to retinal detachment evident, then they will be treated at the same time with laser or a freezing treatment, and a short-acting gas bubble. The gas is slowly absorbed following the surgery over a number of weeks. During that time vision is reduced and you must avoid flying or having a particular form of general anaesthetic (one that involves nitrous oxide) as they would cause expansion of the gas bubble, raised pressure and loss of sight. If a gas bubble is required you are also asked to avoid driving until central vision is restored (usually 1-3 weeks). Once the gas bubble has cleared you will ordinarily be able to continue normal life with no special precautions.At the end of the operation a patch is placed over the eye to protect it whilst the eye remains numbed. This need only be worn for the first night following surgery following which the eye is best left uncovered.
What are the risks of surgery?
Unfortunately all operations have risks. The benefit versus risk ratio is favourable for vitrectomy surgery. Over 90% of people having the surgery are satisfied with the results, but about up to about 5% of people have a visually significant problem afterwards.
Infection - This occurs after less than 1 in 1000 such surgeries but is a sight threatening complication. Urgent attention should be sought after the operation if the eye becomes painful, if the vision starts to deteriorate or if there is increased swelling around the eye; early treatment of an infection improves the outcomes.
Retinal Detachment is a sight threatening problem that is usually treatable with further surgery. Retinal detachment occurs after 1-2% of vitrectomy surgeries, and if it does develop it is usually within 6 weeks of the vitrectomy surgery. This can present with a shadow in the peripheral vision. Again early treatment improves outcomes and so prompt attention should be sought in the event of such symptoms.
Bleeding within the eye at the time of surgery can also be sight threatening but is extremely uncommon when surgery is being performed for floaters.
Cataract - If you have not had cataract surgery previously then the surgery for floaters can hasten the development of cataract in that eye; sometimes a combined lens extraction and vitrectomy procedure is offered to try and avoid successive surgeries.If you have already had cataract surgery then that can make the surgery for floaters more straight forward.
Inflammation - A degree of inflammation is inevitable after surgery and so you will be prescribed steroid eye drops following the surgery. These are usually only required for 3-4 weeks but sometimes they can be required for longer. Inflammation within the other eye as well, potentially threatening the sight in both eyes, is extremely rare at less than 1 in 1 million and is usually treatable.
Cystoid Macula Oedema - Any surgery within the eye can cause swelling of the central retina, which can reduce central vision. It is rare following surgery for floaters alone and is usually, though not always, treatable with a more prolonged course of anti-inflammatory drops or a steroid injection around the outside of the eye. It is seen more commonly following cataract surgeries or if a macular membrane peel is required as part of the surgery.
In the days following surgery
The level of vision following surgery will depend on whether a gas bubble is required or not. Without a gas bubble improvements in vision are typically seen within days. If a gas bubble is required the vision is reduced for a number of weeks until that has been fully absorbed. The eye may feel scratchy initially, but should not be significantly painful. Any redness will usually settle within the first week following surgery.
