Glaucoma Drainage Device (Tube) Surgery overview © Michelle Baker This overview provides general information related to Glaucoma Drainage Device (Tube) Surgery and does not take into account your personal circumstances
GLAUCOMA DRAINAGE DEVICE (TUBE) SURGERY INFORMATION SHEET
Glaucoma Drainage Device (Tube) Surgery
TABLE OF CONTENTS What Is Glaucoma? 3 Eye Appearance After Tube Surgery 3 When Is Tube Surgery Indicated? 3 What Is Tube Surgery and What Does It Do? 4 Pre-Operative Assessment 4 The Surgery Itself 5 Anaesthetic 5 Antimetabolite drugs 6 Donor Tissue 7 After Surgery: Post-Operative Care 7 Immediately after your surgery 7 Day 1 After Your Surgery 8 Eye Drops 8 Post-Operative Clinic Visits 9 Activities After Tube Surgery 9 When Will My Eye Feel Back To Normal? 11 When Can I Go Back To Work? 11 What Are The Success Rates? 11 Are There Any Risks or Complications? 12 Remember 14 Where Can I Get Further Information On Tube Surgery? 14 Glossary 14
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Glaucoma Drainage Device (Tube) Surgery
WHAT IS GLAUCOMA? Where can I get more information on tube surgery? 1. Your ophthalmologist (eye specialist) - Ask me! 2. Glaucoma Australia 3. Glaucoma UK
Glaucoma is the name given to a group of eye disease processes which damage the optic nerve and can lead to vision loss and blindness. Glaucoma typically, but not always, produces elevated pressure inside the eyeball, termed raised intraocular pressure. If glaucoma is detected early, treatment to reduce the intraocular pressure can prevent or reduce vision loss in most patients.
EYE APPEARANCE AFTER TUBE SURGERY
Initially after surgery the eye will be red and swollen to a variable degree. After major eye surgery the eyelid often droops. This normally resolves over a period of weeks to months. After tube surgery, the site of the surgery is not usually visible to the naked eye. Note it may be seen if you look downwards in the mirror and raise your upper eyelid at the same time. However, the plate and its bleb are positioned far back behind the eyelid so they cannot usually be seen. Most patients feel no sensation from the presence of the surgery.
WHEN IS TUBE SURGERY INDICATED?
Tube surgery is indicated for patients whose glaucoma continues to progress despite glaucoma eye drops and/or having had laser treatment and/or where trabeculectomy glaucoma surgery has failed. I will advise tube surgery in specific situations, for example: • Congenital glaucoma • Glaucoma acquired after trauma or inflammation in the eye • Glaucoma due to new blood vessels in the eye • Eyes where the natural lens of the eye has been removed • Where the risks of trabeculectomy surgery failing are much higher
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Glaucoma Drainage Device (Tube) Surgery
WHAT IS TUBE SURGERY AND WHAT DOES IT DO?
Figure 1
Figure 2
The goal of tube surgery is to help lower and control your intraocular pressure. Tube surgery involves inserting a tube into your eye to help lower your intraocular pressure by draining aqueous humour (natural fluid inside the eye) from the eye. This surgery creates a bypass for the impaired natural drain (trabecular meshwork) of your eye. Your intraocular pressure is reduced because fluid can now drain with relative ease through the newly created drainage channel. This surgery will not improve your vision or cure glaucoma, but aims to prevent or slow down further vision loss from glaucoma damage. Tubes have various other names such as tube implants, tube shunts, aqueous shunts and setons. These tubes are made up of a small silicone tube (less than 1mm in diameter) which are attached to a plate (Figure 1). There are a number of different glaucoma drainage tube devices; some with valves e.g. Ahmed Glaucoma Valve and some without e.g. Paul Glaucoma Implant, Baerveldt Glaucoma Implant, Molteno Implant, but they all function in a similar fashion. The tube takes the aqueous humour (natural fluid inside the eye) and drains it to the plate which sits on the sclera (white outer layer of the eyeball) underneath the eye muscles (Figure 2). The plate sits under the conjunctiva (thin skin of the eye which is a thin transparent vascular layer overlying the sclera), under the eyelid.
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Glaucoma Drainage Device (Tube) Surgery
PRE - OPERATIVE ASSESSMENT Figure 3
Figure 4
Figure 5
A pre-operative assessment of your general health will be carried out prior to your surgery. For this assessment please have available an up to date list of your current medications, including blood thinners, and a brief summary of your medical history, available from your GP, if you are unsure. Your general health and suitability for anaesthetic will be assessed. Underlying medical conditions including cardiac disease, uncontrolled high blood pressure and diabetes will need to be addressed prior to scheduling of your surgery. You should continue any eye drops and tablets for your glaucoma, as prescribed, until the time of your surgery. Blood thinning medications such as aspirin and clopidogrel should also be continued, unless directed otherwise. If you take Warfarin this may need adjusting before your operation to ensure it is within the correct therapeutic range. You will receive instructions about fasting prior to your surgery.
THE SURGERY ITSELF Tube surgery often lasts up to two hours. The plate of the device is sutured onto the outside of the eye, the sclera, beneath the conjunctiva, under the upper eyelid (Figure 3). Occasionally other areas are used, such as below the lower eyelid. A small silicone tube is then inserted from this plate into the front of the eye. The length of the tube inside the eye is usually 1 – 2mm (Figure 4). This provides a passageway for the movement of fluid out of the eye to the plate where it can drain away in blood vessels back into the body. The Ahmed glaucoma drainage tube contains a type of valve that helps to prevent very low eye pressure during the first few weeks after surgery. The Paul, Baerveldt and Molteno tube implants do not contain valves but they do have other advantages.
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Glaucoma Drainage Device (Tube) Surgery
However, because they do not have a valve, and until some natural healing occurs around the plate, as a routine at the time of surgery, these tubes are blocked with a stitch that is either tied around the outside of the silicone tube (external ligature) which dissolves after a few weeks, and/ or a stitch which is threaded through the inside of the tube (occluding ligature) which is left partly blocking the tube and can be removed at a later date, if further fluid drainage is needed (Figure 5). The purpose of the stitches is to prevent the silicone tube from draining aqueous humour excessively in the first few weeks after surgery and causing the intraocular pressure to be too low. The silicone tube is then covered by a patch graft to prevent it wearing through the outer conjunctival layer and to prevent infection getting into the eye. The patch graft, taken from the healthy eye of a person who has died (the donor), is transplanted and stitched over the top of the silicone tube onto your eye. Permission to use the tissue has been given either by the deceased prior to death, or more usually by the family. The patch graft of donor tissue is usually sclera.
ANAESTHETIC
Tube surgery is usually performed under general anaesthesia, although local anaesthesia with sedation is also possible under certain circumstances. You will receive instructions from your anaesthetist about fasting prior to the operation.
ANTIMETABOLITE DRUGS
Antimetabolites are medications that prevent scar tissue forming. The most commonly used antimetabolite is Mitomycin C (MMC). If I am concerned that excess scarring could occur and limit the success of your operation, then the use of these medications can limit this process and enhance success. This can be used at the time of surgery.
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Glaucoma Drainage Device (Tube) Surgery
DONOR TISSUE
If donor tissue e.g. sclera, pericardium is not used, breakdown of the conjunctival surface of the eye, over the implant, can occur in 10-14 percent of cases. When donor tissue is used the risk of breakdown is less than three per cent. These tissues do come from donors and are therefore tested to ensure that they cannot transmit known infectious diseases such as Syphilis, Hepatitis B and C and HIV (the AIDS virus). The donor tissue is also very carefully examined to reduce the risk of infection from bacteria and fungi. The medical history of the donor is very carefully checked to exclude the following conditions: Rabies, Creutzfeldt-Jakob disease (CJD) and diseases of the nervous system of unknown cause but it is not tested for prion disease as no suitable test exists. The risk of transmission of prion disease at present appears to be remote. However, because of this minimal risk, once you have had a transplant of donor tissue such as a patch graft, then you will not be able to be a blood or organ donor for the rest of your life.
AFTER SURGERY: POST OPERATIVE CARE IMMEDIATELY AFTER YOUR SURGERY
Your eye will be covered by an eye pad and a protective clear plastic shield. If the unoperated eye does not see well, then the operated eye will only have the clear shield so that it is still possible to see after surgery. Patients are usually discharged home from hospital either the same day as the surgery or the following day. Your eye will be examined one day after surgery. Eye drops are not usually required in your operated eye until the day after surgery. Rest with both eyes closed as much as possible in the days following your tube surgery. You might wish to take pain relieving medication, e.g. paracetamol, to relieve any discomfort. If you are already taking pain relief for a different condition continue with
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Glaucoma Drainage Device (Tube) Surgery
DAY 1 AFTER YOUR SURGERY
Your eye will be examined one day after tube surgery. At that appointment the protective shield will be removed and your eye will be cleaned and examined. Initially your eye will be red and swollen to a variable degree after surgery. 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 the surgery, but then should start to improve. You will be asked to wear a plastic 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 stitches. Some of the stitches dissolve and others are usually removed in the clinic a few weeks after surgery (this takes a couple of minutes in clinic with the eye anaesthetised using eye drops). The eye usually starts to feel more comfortable after the stitches have been removed.
EYE DROPS
Your new eye drops will be prescribed to be used regularly for approximately three months after your surgery. These drops start the day after your surgery, after the post-operative examination. Previous glaucoma drops to the operated eye or Acetazolamide (Diamox) may also initially be continued depending on the type of glaucoma drainage tube chosen but you will need new sterile bottles. It is important that any glaucoma drops to the unoperated eye are continued. The post-operative drops will usually consist of an antibiotic (e.g. Chloramphenicol) and an anti-inflammatory steroid (e.g. Prednefrin Forte). The antibiotic drop needs to be instilled four times per day and the steroid eye drop will initially be used intensively, about 2 hourly, during the day only. Please instill the drops when lying down on your back on one pillow to improve drop retention. The Chloramphenicol needs to instilled first, followed by the Prednefrin Forte 5 to 10 minutes later, to prevent drop dilution. Prednefrin Forte is in a suspension and needs to shaken first. You may notice white particles from the
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Glaucoma Drainage Device (Tube) Surgery
Prednefrin Forte in your eyelashes or in the corner of your eye, which allow the drop to continue working. You will initially be given a prescription for a supply of the post-operative drops which lasts about one month. At each post-operative visit you will be advised whether a change of dosage or drop is required. If you are running out of drops you must obtain a repeat prescription, usually from calling the rooms and it can be sent directly to your pharmacy.
POST - OPERATIVE CLINIC VISITS
Patients are usually reviewed once a week for the first four weeks, and may be seen more frequently if the eye pressure is either too high or too low. Your intraocular pressure can fluctuate widely in the first few weeks after surgery. It is very important that you attend all your clinic appointments, and use your eye drops as prescribed.
ACTIVITIES AFTER TUBE SURGERY Following your tube surgery, you are able to read and watch television as normal as these activities will not harm your eye. It is, however, important to avoid strenuous/water-based activities during the early post-operative period including swimming, jogging, gardening and contact sports. Avoid heavy lifiting or bending, including activities such as yoga that requires head-down posturing. As a general rule, it is important that you do not bump, rub or press on your eye after surgery. Avoid coughing or sneezing, if possible. It is recommended you consult with me before commencing any strenuous activity. The following table is a general guide but can be altered depending upon how each individual’s eye recovers.
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Glaucoma Drainage Device (Tube) Surgery
ACTIVITY
ADVICE
Hair washing
No need to avoid but back wash advised to avoid getting shampoo and water into your eye. It may be easier to have someone else wash your hair for you.
Showering and bathing
No need to avoid but don’t allow soapy or dirty water to go into your eye.
Sleeping
Try to sleep on your un-operated side. Tape the clear plastic eye shield provided over your eye every night for 2 weeks to avoid accidentally rubbing your eye whilst asleep.
Walking
No restrictions.
Wearing spectacles
No restrictions. Avoid buying new spectacles until 3 months after surgery, as your spectacle prescription can change during this time, as your eye heals.
Wearing sunglasses
Wear for comfort, if your eye feels sensitive to light and wear sunglasses in bright sunlight with UV protection.
Wearing contact lenses
Should not be worn in the immediate post-operative period, but may be worn in longer term, after discussion with me.
Driving
This is dependent on your vision in both eyes and you will be advised at clinic.
Flying
No restrictions but bear in mind your frequent postoperative visits to ensure that the glaucoma drainage device is functioning properly and that the intraocular pressure is at the correct level.
Going away on holiday
Discuss with me first as it is critical to attend your follow up appointments. In the 3 month post-operative period I prefer you to be in close proximity, so if problems arise I can review you promptly
Wearing eye make up
Avoid for 1 month, then use new make-up. Never share eye make-up with someone else.
Household chores e.g. cleaning, ironing, vacuum cleaning
Avoid for 1 – 2 weeks but this depends upon your intraocular pressure.
Sexual activity
Avoid for 1 -2 weeks.
Gym workout
Avoid for 3 months.
Playing sports e.g. football, tennis, golf
Avoid for 3 months.
Running / jogging
Avoid for 3 months.
Swimming
Avoid until all your stitches have been removed, and for approximately 3 months, (check with me first) then after that wear goggles with a horizontal internal diameter of at least 52mm.
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Glaucoma Drainage Device (Tube) Surgery
WHEN WILL MY EYE FEEL BACK TO NORMAL?
Following tube surgery, in most cases, it takes 2 to 3 months for the eye to feel completely normal and sometimes longer in more complicated cases following tube surgery.
WHEN CAN I GO BACK TO WORK? The length of time you will need off work depends upon a number of factors. These include the nature of your job, your vision and the intraocular pressure in your operated eye. Typically, most people require two weeks off work after surgery, if the post-operative course is smooth. If your occupation involves heavy manual work or you work in a dusty/dirty environment (e.g. builder, farmer) you may require longer off work. This can be discussed at any clinic visit. You may need to make your employer aware of your need to attend for frequent follow up appointments after your tube surgery.
WHAT ARE THE SUCCESS RATES? Audits and studies on the success of tube surgery tube surgery demonstrate it is effective in lower intraocular pressure. Most glaucoma surgical studies examine success rates over a five year period. In the Tube versus Trabeculectomy (TVT) study [1] the expected success rate over five years is about 70 percent. In the TVT study there was a failure rate of about 10 percent each year: 4% at one year, 15% at 3 years and 30% at 5 years. A blockage of the tube in the eye or too much scarring around the drainage plate can limit the success of the operation. Although a sizeable proportion of patients achieve good intraocular pressure control without the need for continued glaucoma medication, many patients still require some medication to assist the glaucoma drainage device in controlling the intraocular pressure. In such circumstances,
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Glaucoma Drainage Device (Tube) Surgery
the medication required is usually less than that required after surgery. In the TVT study the average patient achieved an intraocular pressure of 14.4s mmHg, on an average of one glaucoma eye drop medication. Patients often ask about long term success over 10 years, 15 years or more. Because of the expense and other difficulties in performing very long-term studies, most research studies do not answer this question. Studies that have been carried out over longer periods show that most implants which are functioning successfully at five years continue to do so over longer periods of time.
ARE THERE ANY RISKS OR COMPLICATIONS? Severe complications are uncommon but are most likely to happen if the intraocular pressure drops very low or very quickly in the early post-operative period. About five percent of patients following tube surgery require a return to the operating theatre in the first month after surgery for adjustment, either because of low or high intraocular pressure. • Choroidal haemorrhage: The most serious problem that can occur is bleeding inside the eye. A very low or an abrupt drop in intraocular pressure can result in a choroidal haemorrhage which is severe bleeding at the back of the eye. This can lead to loss of vision and even blindness but occurs in less than 1 in 1,000 patients. • Infection: An infection inside the eye can be very serious and also cause loss of vision or blindness. This happens in less than 1 in 1,000 patients. • Tube complications: There is a small long-term risk that the tube will develop a blockage (requiring further surgery to unblock the tube); erode (the surface conjunctiva over the tube breaks down, requiring a repair operation). • Corneal decompensation: This can occur if the tube rubs against the cornea requiring further surgery to either move the tube so it does not rub or, in extreme cases where significant corneal damage has occurred, a corneal transplant may be required to restore vision.
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Glaucoma Drainage Device (Tube) Surgery
• Intraocular pressure not at target: After surgery the intraocular pressure can be too high or too low. Initially it is likely that glaucoma medications will need to be taken until drainage from the tube occurs. This might require additional treatment or adjustments in the outpatient clinic or sometimes further surgery is required. There is a small risk of the pressure going too low when the tube does drain and this can cause a reduction in vision. • Inflammation: Inflammation inside the operated eye can occur and can be treated with eye drops. Rarely, inflammation of the unoperated eye, called sympathetic ophthalmia, and causes total or partial loss of vision, in the unoperated eye. • Cystoid macular oedema: Swelling in the retina can affect your vision but this can usually be treated with medication. • Discomfort: Some patients are aware of the drainage plate under the upper eyelid but this usually settles down with time. The drainage bleb may become large and affect the tear film on the eye surface, which can create a feeling of discomfort or dryness of the eye. This occurs in about 10% of patients and is usually treatable with lubricants. Occasionally, the discomfort is more severe and requires surgery to make the drainage bleb smaller. • Ptosis: Some patients are aware there is slight drooping of the eyelid but this usually settles down with time. • Astigmatism/change in glasses prescription: Most patients require a change in their spectacles after tube surgery. Patients should refrain from changing their spectacles until at least 3 months after surgery and only once the intraocular pressure has stabilised. It is advisable to check with me before changing your spectacles. Rarely, a patient who does not require spectacles before surgery, develops a need for them after surgery. • Double vision: The plate, and drainage around it, can affect the movement of the eye and cause double vision. • Decreased vision: About 10% of patients notice that their vision is reduced by one line on the eye chart over year after tube surgery. This is often due to cataract formation which can be corrected by cataract surgery.
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Glaucoma Drainage Device (Tube) Surgery
REMEMBER
The information in this leaflet is intended as a guide only, as each patient’s experience will be different. Do not wait until your next appointment, but contact me immediately, if you have: • • • • •
Redness Vision disturbance such as double vision Fluctuating or loss of vision Increasing Pain Concerned
WHERE CAN I GET FURTHER INFORMATION ON TUBE SURGERY 1. Your ophthalmologist - Ask me! 2. Glaucoma Australia 3. Glaucoma UK
GLOSSARY • Glaucoma the name given to a group of eye disease processes which damages the optic nerve and can lead to vision loss and blindness. • Intraocular pressure is the pressure inside your eyeball. • Glaucoma Drainage Device (tube) surgery creates an alternative drainage pathway to help aqueous fluid drain from your eye to lower the intraocular pressure. • Scleral flap or “flap” is the thin trap door in the sclera where the aqueous humour drains through. • Sclera is the protective outer white layer of the eye, under the conjunctiva. • Drainage bleb or “bleb” is a reservoir of aqueous humour under the upper eyelid. • Aqueous humour is the natural fluid inside the eye. • Conjunctiva or “skin of the eye” is the thin transparent vascular layer overlying the sclera and it also lines the inside of the eyelids.
References: 1. Gedde SJ et al. Treatment Outcomes in the TVT Study After Five Years of Follow up. AMJ. 2012. May;153(5):789-803.
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