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Trabeculectomy (tra·bec·u·lec·to·my) is a type of surgery for glaucoma that involves creating a small flap in the sclera (the outer white layer of the eyeball). The scleral opening is covered with a thin trapdoor that allows the aqueous humour (the transparent fluid that maintains intraocular pressure, which plays a key role in the existence of glaucoma) to drain out of the eye but will also prevent fluid from draining too quickly. The fluid then collects in a reservoir (filtering bleb) that is hidden under the upper eyelid. The drainage of the aqueous humour through the trapdoor aims to reduce the eye pressure more effectively than drops to slow down further vision loss from glaucoma.2
Trabeculectomy is the gold standard in surgical procedures for glaucoma patients - with a 70-90% success rate of intraocular pressure remaining lowered for at least one year.3 The most frequent reason for the procedure to be unsuccessful is bleb failure, where the postoperative wound healing process closes off the trap door.
Trabeculotomy (tra·bec·u·lo·to·my) is the procedure of choice in children with congenital glaucoma. It is preferred over trabeculectomy because it is less invasive and has a lower risk of causing cataracts. It is also more effective in lowering intraocular pressure (IOP) in children, with a success rate of around 80%.11
This procedure involves the removal of a small piece of tissue from the drainage angle in the eye to create an artificial opening. This allows the aqueous humour to then drain out of this new opening, in turn lowering the intraocular pressure.
A viscocanalostomy (vis·co·can·al·os·to·my) is a type of surgery that involves the injection of a viscoelastic material (a material that has properties of both the solid and liquid phase) into the eye. This injection dilates the canal and disrupts the layers of the trabecular meshwork (an area of tissue near the base of the cornea that is responsible for draining the aqueous humour from the eye). This procedure allows the aqueous humour to slowly percolate out of the anterior chamber (the space inside the eye between the iris and the cornea’s innermost surface, the endothelium) of the eye through normal drainage channels.
This option has several advantages over conventional trabeculectomy. For example, no scleral opening is created, which avoids sudden drops in intraocular pressure — and also lowers the risk of cataract formation and infection. Instead of relying on an artificial opening in the sclera, the procedure restores the natural outflow pathways, which makes it independent of scarring - the leading cause of trabeculectomy failure. It’s worth noting, however, that results are not as good as trabeculectomy over the long-term and not everyone is a candidate for viscocanalostomy, so consulting your ophthalmologist about this option, as with other options, is important.6
A deep sclerotomy (scler·o·to·my) is an innovative, minimally invasive surgical procedure for open-angle and juvenile glaucoma which allows the intraocular pressure to be lowered without opening the anterior chamber or entering the eye. The procedure removes some of the tissue responsible for limiting the rate of aqueous outflow, which aims to allow more aqueous to drain out of the eye. This, in turn, lowers eye pressure.
Although the procedure has been shown to decrease IOP significantly for at least six years, with no serious complications reported, 7 there remains some debate surrounding the overall efficacy.
Trabecular stent bypass
This is a type of minimally invasive glaucoma surgery that relatively new in the UK as an alternative method of reducing intraocular pressure. The trabecular stent bypass procedure involves the placement of a stent (tiny tube) to directly drain aqueous humour from the anterior chamber into Schlemm’s canal (a vessel in the eye that collects aqueous humour from the anterior chamber) thereby bypassing the obstruction at the level of the trabecular meshwork.
Opinion on the effectiveness of trabecular stent bypass varies. One study, for example, found that up to 70% of patients are able to discontinue pressure-lowering anti-glaucoma medications after the procedure.8 More substantial research into the procedure does need to be undertaken, however, to properly assess the effectiveness of it.12
Selective Laser Trabeculoplasty (SLT)
A selective laser trabeculoplasty (tra·bec·u·lo·plas·ty) is usually recommended for people with open-angle glaucoma that continues to progress despite treatment with pressure-lowering eye drops.9 In a single outpatient laser procedure, SLT reduces intraocular pressure by increasing aqueous outflow through the trabecular meshwork. This, in turn, helps reduce intraocular pressure and prevent or slow down further vision loss in glaucoma patients.
SLT has minimal recovery time, is comparable to medical treatment, and can even delay or prevent the need for eye drops - thus avoiding the associated side-effects. Importantly, the effect of SLT is not permanent, but the procedure can be repeated.
Recovery and aftercare following glaucoma surgery
The recovery time for invasive procedures can be several weeks and it’s advisable to keep water out of the eye during recovery. Patients should also avoid reading, bending, heavy lifting, and driving for as long as advised by their ophthalmologist. The aftercare for each type of glaucoma surgery can be different, so you should always check with your ophthalmologist and follow their specific advice. Here are some tips to ensure the best recovery:10
- Leave the padding/eye patch in place over the operated eye for the first day to prevent external injury.
- Keep your face clean and avoid touching the eye to prevent an infection.
- Avoid using eye make-up for as long as directed.
- Avoid activities that expose the eye to water (for example, showering).
- Wash your hands before using eye drops.
- Use the postoperative antibiotic and anti-inflammatory eye drops as instructed.
- Protect the eye with goggles, especially in windy weather and during sports.
- Be alert for signs of postoperative complications (for example, sudden changes in vision, severe pain, redness, pus discharge, or halos around light bulbs).
- Keep all your follow-up appointments.
Ultimately, if you feel like you need more advice on what treatment options to choose, then book an appointment for an eye test. Our expert optometrists will help you understand your condition further, and may refer you to an ophthalmologist who can take a closer look at your options.
Alternatively, if you’re interested in learning more about the treatment options for glaucoma, head over to our dedicated treatment resource page.
1. Mahabadi N, Foris LA, Tripathy K. [Updated 2019 May 13]. Open Angle Glaucoma. In: StatPearls [Internet]. Treasure Island (FL): StatPearls Publishing; 2019 Jan-. [Online]. Available at: https://www.ncbi.nlm.nih.gov/books/NBK441887/ [Accessed 12 August 2019].
2. International Glaucoma Association. (no date). What is Trabeculectomy. [Online]. Available at: https://www.glaucoma-association.com/about-glaucoma/treatments/surgery/trabeculectomy/ [Accessed 12 August 2019].
3. Glaucoma Research Foundation. (no date). Incisional Surgery. [Online]. Available at: https://www.glaucoma.org/treatment/conventional-surgery.php [Accessed 12 August 2019].
4. Broadway, David C. MD, BSc, FRCOphth DO; Chang, Lydia P. FRCOphth. (2001). Trabeculectomy, Risk Factors for Failure and the Preoperative State of the Conjunctiva. Journal of Glaucoma: June 2001 - Volume 10 - Issue 3 - p 237-249. [Online]. Available at: https://journals.lww.com/glaucomajournal/Citation/2001/06000/Trabeculectomy,_Risk_Factors_for_Failure_and_the.17.aspx [Accessed 12 August 2019].
5. Health Link British Columbia. (no date). Trabeculectomy for Congenital Glaucoma. [Online]. Available at: https://www.healthlinkbc.ca/health-topics/hw241689 [Accessed 12 August 2019].
6. Carassa, Roberto G. (2014). Glaucoma (Second Edition), Viscocanalostomy: Available online 2 September 2014. Volume 2, 2015, Pages 960-965. [Online]. Available at: https://www.sciencedirect.com/science/article/pii/B9780702051937000984 [Accessed 12 August 2019].
7. Pajic B, Pajic-Eggspuehler B, Haefliger I. (2011). New minimally invasive deep sclerotomy ab interno surgical procedure for glaucoma, six years follow-up. Journal of Glaucoma, 2011 Feb;20(2):109-14. [Online]. Available at: https://www.ncbi.nlm.nih.gov/pubmed/20520572 [Accessed 12 August 2019].
8. Resende, AF, Patel, NS, Waisbourd M, and Katz LJ. (2016). iStent Trabecular Microbypass Stent: An Update. Journal of Ophthalmology, 2016; 2016: 2731856, published online 2016 Jun 20. [Online]. Available at: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC4931099/ [Accessed 12 August 2019].
9. Gazzard, G., et al. . Selective laser trabeculoplasty versus eye drops for first-line treatment of ocular hypertension and glaucoma (LiGHT): a multicentre randomised controlled trial. [Internet]. The Lancet. [Online]. Available at: https://www.thelancet.com/journals/lancet/article/PIIS0140-6736(18)32213-X/fulltext [Accessed 7 November 2019].
10. Kyari F and Abdull MM. (2016). The basics of good postoperative care after glaucoma surgery. Community Eye Health Journal. Volume 29 (94); 2016. [Online]. Available at: https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5100471/ [Accessed 12 August 2019].
11. Glaucoma Research Foundation. (no date). Childhood Glaucoma. [Online]. Available at: https://www.glaucoma.org/uploads/grf_childhood_glaucoma.pdf
12. Gazzard, G. (no date). Minimally Invasive Glaucoma Surgery: MIGS. The Royal College of Ophthalmologists. [Online]. Available at: https://www.rcophth.ac.uk/wp-content/uploads/2016/05/CN-Focus-Spring-2016.pdf [Accessed 7 Nov 2019].