MAXIMISING THE SUCCESS RATE IN GLAUCOMA FILTRATION SURGERY
(FOR THE PATIENT AND THE PHYSICIAN)

Professor P T Khaw PhD FRCP FRCS FRCOphth FIBiol FRCPath FMedSci

Professor of Glaucoma and Wound Healing
And Consultant Ophthalmic Surgeon
Moorfields Eye Hospital and the Institute of Ophthalmology
London, UK EC1V 9EL
p.khaw@ucl.ac.uk

Recent research has suggested that glaucomatous progression can be arrested in the majority of patients over a decade or more if pressure can be controlled in the 10-15 mmHg range. This can often only be achieved with filtration surgery, and adjunctive agents to prevent scarring which is the most important determinant of long-term intraocular pressure.

However, this often comes at a price including hypotony and all its consequences including flat chambers, cataracts, choroidal effusions and haemorrhage, and in the longer-term cystic uncomfortable blebs, with leakage, blebitis and endophthalmitis and paradoxically still failure in the long-term due to scarring.

Although we often focus on “ocular endpoints” we are increasing aware that enhanced surgery comes at a cost to the patient – prolonged periods of poor vision and discomfort, and multiple visits for treatment. We need to continue to strive for a surgical technique that will begin to meet up to the short and long-term results of modern cataract surgery with the individual patient at the heart of the drive for improvement.

In this presentation I will outline the improvements in glaucoma surgery and wound healing modulation which will help us achieve better long-term results with less complications, particularly from the patients point of view. These improvements have been developed into a ”Safer surgery system” for filtration surgery which include:

1) The judicious use of antimetabolites at the time of and after surgery including 5-fluorouracil and mitomycin-c. The scientific basis of these agents will be outlined which helps us to optimise their use

2) The method of applying antimetabolite intra-operatively. Increases in the surface area of application, larger scleral flaps and fornix based incisions has led to a dramatic reduction in cystic blebs and long term complications such as endophthalmitis (20% to 0% over a 5 year follow up period in a high risk group)

3) Intraoperative infusion techniques such as a simple intraoperative infusion to allow accurate titration of outflow to prevent postoperative hypotony and maintain visual acuity in the postoperative period
.
4) The use of tight suturing techniques with both releasable and the new technique of adjustable sutures which allow a gradual safe titration of intraocular pressure.

5) Better methods of applying post operative anti-scarring agents including the use of viscoelastics and viscodissection.

6) The use of newer anti-scarring techniques including “smart” agents such as human monoclonal antibody to transforming growth factor beta-2 (TrabioR) which has a much better safety profile and is now through to a multicentre trials around the world. Other very promising future treatments will also be presented.

Further reading list

Smith MF, Sherwood MB, Doyle JW, Khaw PT. Results of Intraoperative 5-Fluorouracil Supplementation on Trabeculectomy for Open-angle Glaucoma. Am J Ophthalmol 1992;114:737-741.

The Fluorouracil Filtering Surgery Study Group. Three year filtering surgery study group. Am.J.Ophthalmol. 1993;115:82-92.
Migdal C, Gregory W, Hitchings RA. Long-term functional outcome after early surgery compared with laser and medicine in open-angle glaucoma. Ophthalmology 1994;101:1651-1657.

Collaborative normal-tension glaucoma study group. Comparison of glaucomatous progression between untreated patients with normal-tension glaucoma and patients with therapeutically reduced intraocular pressures. Am J Ophthalmol 1998;126:487-497.
Katz GJ, Higginbotham EJ, Lichter PR, et al. Mitomycin C versus 5-fluorouracil in high-risk glaucoma filtering surgery. Ophthalmology 1995;102:1263-1269.

Singh K, Egbert PR, Byrd S, et al. Trabeculectomy With Intraoperative 5-Fluorouracil vs Mitomycin C. Am.J.Ophthalmol. 1997;123:48-53.

Membrey WL, Poinoosawmy DP, Bunce C, Hitchings RA. Glaucoma surgery with or without adjunctive antiproliferatives in normal tension glaucoma: 1 intraocular pressure control and complications. Br J Ophthlamol 2000;84:586-590.
Khaw PT Wilkins MR Shah P. Glaucoma Surgery. Oxford Textbook of Ophthalmology. Eds: Easty D Sparrow J. Oxford Univ 1999

Chang L,Cordeiro, MF. Crowston JG, Akbar AN, Khaw PT. The role of the immune system in normal conjunctival wound healing after glaucoma surgery. Surv Ophthalmol 2000;45:49-68.

Wormald R, Wilkins MR, Bunce C. Post-operative 5-fluorouracil for glaucoma surgery. (systematic review) Cochrane Database Syst Rev 2000;2:

Khaw PT Sherwood MB Doyle JW Smith MF McGorray S Prolonged localised conjunctival and sclera tissues effects after short term treatments with mitomycin-C or 5-FU Arch Ophthalmol 1993: 111; 263-267

Mead AL Wong TTL Cordiero MF Anderson IK Khaw PT Anti-Transforming Growth Factor–b2 antibody: a new post operative anti-scarring agent in glaucoma surgery Invest Ophthalmol Vis Sci 2003; 44: 3394-3401

Wilkins M Occleston N Waters L Kotecha A Khaw PT Effects of sponge type, size and application technique on tissue levels of 5-fluorouracil Br J Ophthalmol 2000; 84: 92-97

Khaw PT Clarke JCK Mead AL Wong TTL Daniels JT Controlling tissue repair and regeneration after surgery: new treatments and techniques Basel Glaucoma Symposium Ed Sharaawy T Flammer J Ciba Vision 2003

Well AP Cordeiro MF Bunce C Khaw PT Reduction in cystic bleb complications after Mitomycin-c trabeculectomy using fornix versus limbus based incisions Ophthalmology 2003 (In press)