The aqueous humour that drains through the trabeculectomy accumulates in a reservoir between the sclera and the surface layer of tissue that covers the eyeball (the conjunctiva) to form a small drainage bleb that is usually hidden under the upper eyelid.
What is the appearance of the eye after a trabeculectomy?
Initially the eye is red and swollen to a variable degree after surgery. The eyelid may also droop partially. This usually resolves over a period of weeks to months. The drainage bleb is not usually visible to the naked eye after the trabeculectomy operation. The bleb may, however, be seen if the patient looks in the mirror and raises the upper eyelid.
After surgery, most patients feel no sensation from the presence of the drainage bleb. Rarely, patients are aware of the drainage bleb. Should this occur, steps can be taken to make the bleb more comfortable; this is discussed further under complications.
Medication prior to surgery
Prior to undergoing surgery, patients are asked to continue all drops and tablets in accordance with their normal treatment regimen until the morning of the operation. Blood thinning medications should also be continued. Nevertheless, your doctor may ask you to stop taking blood thinning medication prior to surgery to ensure it is within the correct therapeutic range.
If patients opt to have the surgery performed under general anaesthesia, a pre-operative assessment of their general health will be carried out just before surgery. Underlying medical conditions including cardiac disease, uncontrolled high blood pressure and diabetes are addressed prior to scheduling of surgery.
The surgery itself
Trabeculectomy surgery typically lasts up to 45 to 60 minutes.
Trabeculectomy surgery is often performed under local anaesthesia, though it may also be performed under general anaesthesia.
Patients who have their surgery under local anaesthesia are awake during the operation but will have the option of requesting light sedation. The eye is anaesthetised first with eye drops and then an injection of anaesthetic is administered around the eye. The anaesthetic injection itself may cause some mild discomfort; a slight sensation of pressure as the anaesthetic is delivered. The injection anaesthetises the eye, preventing not only pain but also excessive eye movement during surgery. During surgery patients are covered by a sterile sheet, or drape, which keeps the operation site sterile and also prevents patients from seeing any of the surgery. Patients will be aware of the surgeon working around the eye, but should not feel pain. In the event of any pain or discomfort, the patient may calmly raise a hand and the surgeon will stop the surgery and top-up the anaesthetic if needed. Patients may also hear the surgeon speaking to the scrub nurse and other members of the surgical team.
After surgery – Post-operative care
Patients are usually discharged home from hospital either the same day as the surgery.
Please note; all patients need to be examined one day after surgery so a further visit to the clinic the following day is required for those having day case surgery.
The eye is normally padded after surgery and the eye pad is removed the following day. If the unoperated eye does not see well, then the operated eye will not be padded. Instead, a clear shield will be placed on the operated eye so that it is still possible to see after surgery.
Patients are advised to ask a friend or relative to accompany them home after surgery, especially patients who have poor sight in the unoperated eye or those who have had general anaesthesia.
What should I expect to feel during the post-operative period?
It is normal for the vision to be blurred and the eye to be uncomfortable after surgery. The period of blurring is variable. The vision may be particularly blurred for one to two weeks following surgery, and then start to improve. It can take two to three months for the eye to feel completely normal and the vision to stabilise completely.
The patient will also be asked to wear a shield at night for the first two weeks or so; this is to prevent any accidental harm to the operative site whilst sleeping.
Soreness in the eye after surgery is partly due to the surgery itself, and partly due to the sutures (or stitches). The sutures do not dissolve and are usually removed in the clinic two to three weeks after surgery (this takes two to three minutes in clinic with the eye anaesthetised using eye drops). The eye usually starts to feel more comfortable after the sutures have been removed.
Eye drops after surgery
Eye drops will be prescribed to use regularly after surgery. These start the day after surgery, after the post-operative examination. It is not usually necessary to use eye drops the first night after the surgery. Acetazolamide (Diamox) tablets or any glaucoma medication to the operated eye should also be stopped the night after surgery unless advised otherwise.
It is important that any eye drops for the unoperated eye are continued unless advised otherwise.
The post-operative eye drops will usually consist of an antibiotic and anti-inflammatory steroid. Patients are given a supply of post-operative eye drops on leaving the clinic; these should last one month. The post-operative eye drops will normally need to be taken for two to three months. Patients are advised at each post-operative visit whether a change in the dosage of drops is required. The drops should not be stopped or the dosage changed without consulting the doctor.
Post-operative clinic visits
Patients are usually seen once weekly for the first four weeks, and may be seen more frequently if the eye pressure is either too high or too low.
Activity after surgery
It is important to avoid strenuous activity during the early post-operative period including swimming, jogging and contact sports.
It is permissible to watch television and read, as these will not harm the eye.
As patients will be monitored closely following surgery, it is recommended that they consult their surgeon before commencing strenuous activity. If the eye pressure is very low after surgery the surgeon may suggest refraining from all exertion and remaining sedentary until the pressure is restored.