Clinical and Experimental Ophthalmology 2006; 34: 732–733doi:10.1111/j.1442-9071.2006.01396.x

© 2006 Royal Australian and New Zealand College of Ophthalmologists

Editorial

Refractory glaucoma – here there be dragons

The first seton, described in 1907 was horse’s hair insertedinto anterior chamber through a paracentesis.3 It was over60 years before Molteno markedly improved outcomes bythe tube and plate design,4 leading to a number of currentlyavailable setons. A recent meta-analysis of seton surgery byMinckler et al. concluded: ‘relatively few randomized trialshave been published on aqueous shunts and methodologyand data quality among them is poor. To date there is noevidence of superiority of one shunt over another.’5 Interest-ingly, the intraoperative use of MMC in seton surgery doesnot seem to improve outcomes.6,7 A large, prospective, ran-domized study8 is currently comparing the safety and effi-cacy of non-valved seton surgery to MMC trab in patientswith previous intraocular surgery, and should help with sur-gical decision making in ‘mild’ refractory glaucoma.

Cyclodestructive procedures have historically been asso-ciated with severe complications, including phthisis and sym-pathetic ophthalmia; hence, they tended to be used as a lastresort. However, more recently, a number of reports havehighlighted the relative safety and efficacy of cyclodiode inrefractory glaucoma.9,10 These data along with its technicalease and convenience as an office procedure have made it anincreasingly appealing option. In this issue, Malik et al. in a ret-rospective study, compare the outcomes of seton surgery withcyclodiode in refractory glaucoma.11 The authors are wellaware of the study’s limitations, in particular, that selection biasmakes comparisons difficult. The mean age of the cyclodiodegroup was significantly younger (P = 0.03, t-test) than the tubegroup and it contained a greater number of neovascular cases(but not significantly, P = 0.12 chi-squared test). When theneovascular cases are included in the analysis, the ‘surgical suc-cess’ is significantly greater in the seton group, but when theneovascular cases are excluded, it is not. The authors’ con-clusion that the relative IOP-lowering efficacies of the twotreatment modalities are comparable seems valid and they sug-gest the need for a randomized, controlled trial in a larger pop-ulation to fully evaluate the optimum intervention for themanagement of the different refractory glaucomas.

Whether or not MMC trab is a better surgical option thancyclodiode or seton surgery in certain cases remains unclear,and our outcomes may ultimately be optimized by a detailedunderstanding of the clinicopathology of subconjunctivalfibrosis.

Robert J Casson DPhil, FRANZCOSouth Australian Institute of Ophthalmology, Department of

Ophthalmology and Visual Sciences, University of Adelaide, Adelaide,South Australia, Australia

Not so long ago, there was scarce robust evidence to guideour clinical decision-making in glaucoma. However, therecent evidence-based driven collection of high qualityresearch has provided gold-standard management adviceacross a range of clinical scenarios: the coastlines of ourmanagement maps now appear in much greater detail, andonce vague land masses have become better defined. Thereremains one area, however, where evidence is thin, where weare still guided principally by experience, hearsay and whis-pers: the realm of refractory glaucoma.

Refractory glaucoma is a term which refers to the sub-group of conditions where medical treatment is insufficientand conventional trabeculectomy is prone to bleb failure dueto aggressive subconjunctival fibrosis. Many glaucoma spe-cialists carry a kind of league table of risk factors for blebfailure in their head, which includes (in no special order) age,race, trauma, previous filtration surgery, vitreoretinal surgeryor other intraocular surgery, uveitis, aphakia, iridocornealendothelial syndromes and neovascular glaucoma. Whilethere may be some consensus as to the premiership contend-ers, there would be considerable disagreement about theexact league order. Indeed, the inclusion of certain risk fac-tors would be controversial: Is laser iridotomy a risk factor?Quiescent uveitis? What about pterygium excision? Or clearcorneal phaco? To add to our ignorance, we have little evi-dence for the optimal surgical approach in refractory cases.Like sailors venturing into uncharted waters seeking advicefrom old sea captains, second opinions are often sought fromveteran colleagues. But beware: seek more than one opinion,and you will find more than one opinion.

Arguably, the three principal management options forrefractory glaucoma are trabeculectomy augmented withmitomycin C (MMC trab), seton surgery, and transscleraldiode laser cyclophotocoagulation (cyclodiode). Antimetab-olites have revolutionized the management of cases at highrisk for failure, and many glaucoma surgeons titrate the con-centration and/or the duration of application of mitomycinC (MMC) depending on the perceived risk of bleb failure.However, the relative risk and the way in which multiple riskfactors interact remains poorly understood, and the optimaldosage remains guesswork. Furthermore, following the evi-dence-based drive for lower target IOPs, many glaucomasurgeons routinely use intraoperative MMC in cases tradi-tionally considered at low risk for bleb failure.1 A recentsystematic review of the MMC trab-related literature con-cluded that intraoperative MMC reduces the risk of surgicalfailure in eyes that have undergone no previous surgery andin eyes at high risk of failure.2

Editorial 733

© 2006 Royal Australian and New Zealand College of Ophthalmologists

REFERENCES

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2. Wilkins M, Indar A, Wormald R. Intra-operative mitomycinC for glaucoma surgery. Cochrane Database Syst Rev 2005 (4):CD002897.

3. Lim KS, Allan BD, Lloyd AW, Muir A, Khaw PT. Glaucomadrainage devices; past, present, and future. Br J Ophthalmol1998; 82: 1083–9.

4. Molteno AC. New implant for drainage in glaucoma. Clinicaltrial. Br J Ophthalmol 1969; 53: 606–15.

5. Minckler DS, Vedula SS, Li TJ et al. Aqueous shunts for glau-coma. Cochrane Database Syst Rev 2006 (2): CD004918.

6. Lee D, Shin DH, Birt CM et al. The effect of adjunctive mito-mycin C in Molteno implant surgery. Ophthalmology 1997; 104:2126–35.

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9. Shah P, Lee GA, Kirwan JK et al. Cyclodiode photocoagulationfor refractory glaucoma after penetrating keratoplasty. Ophthal-mology 2001; 108: 1986–91.

10. Walland MJ. Diode laser cyclophotocoagulation: longer termfollow up of a standardized treatment protocol. Clin ExperimentOphthalmol 2000; 28: 263–7.

11. Malik R, Ellingham RB, Suleman H, Morgan WH. Refractoryglaucoma – tube or diode? Clin Experiment Ophthalmol 2006; 34:771–7.