Non-enhanced trabeculectomy by non-glaucoma specialists: Are results related to risk factors for failure?

Purpose To determine the 1 year success rate of non-enhanced trabeculectomy under the care of non-glaucoma specialists and the effects of risk factors on the surgical outcome as measured by

intraocular pressure (IOP) control.

Methods A retrospective study of 167 patients undergoing trabeculectomy was performed. One hundred and four cases were performed in a teaching hospital and 63 in a district general hospital

(DGH). Non-glaucoma specialists performed all the operations, enhanced trabeculectomy with antimetabolites being excluded. Information was recorded from a retrospective review of case notes,

and post-operative IOPs at 12 months follow-up were analysed. Risk factors for failure were defined as: (1) age less than 40 years old, (2) black race, (3) diabetes mellitus, (4) miotic

therapy 18 months, (5) sympathomimetic therapy 6 months, (6) pseudophakia or aphakia, (7) previous failed filtration procedure, (8) argon laser trabeculoplasty, (9) previous ocular surgery

and (10) high-risk glaucoma (angle recession glaucoma, uveitic flaucoma and neovascular glaucoma). A iuccess was defined to be a post-operative IOP at 1 year of less than 21 mmHg and at

least 20% less than the presenting IOP on no medication.

Results The overall success rate was 139 of 167 (83.2%). Eighty-seven of 104 eyes (83.7%) were Classified as a success in the teaching hospital group and 52 of 63 (82.5%) were classified as

a success in the DGH group. There was no significant difference in the number of risk factors between the success and failure groups. Eyes with two or more risk factors had significantly

higher IOPs at 1 year when compared with eyes with 0 or 1 risk factor (mean ± SD: 17.4 ± 6.34 mmHg vs 14.2 ± 5.0 mmHg, p = 0.022). When only ‘successful eyes’ were analysed, those with two

or more risk factors still had significantly higher IOPs at 1 year (mean ± SD: 15.0 ± 3.0 mmHg vs 12.8 ± 3.9 mmHg, p = 0.046). There were significantly fewer eyes in the two or more risk

factor group with IOPs < 16 mmHg at 1 year (26.1% vs 60.4%, p = 0.021).

Conclusions Eyes at relatively low risk for failure operated upon by non-glaucoma specialists appeared to have success rates similar to previously published series. Eyes with two or more

risk factors for failure have higher IOPs at 1 year in non-enchanced trabeculectomy. Adjunctive anti-scarring agents may be considered for these patients when filtration surgery is

scheduled.

This paper was partly presented as a poster at the Annual Congress of the Royal College of Ophthalmologists, Cardiff, 1999

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