Editors Selection (IGR: 16-3) | International Glaucoma Review #45

Editors Selection IGR 16-3

Surgical treatment: SLT and medical therapy

Comment by Karim Damji on:

13087 A randomised, prospective study comparing selective laser trabeculoplasty with latanoprost for the control of intraocular pressure in ocular hypertension and open angle glaucoma, Nagar M; Ogunyomade A; O'Brart DP et al., British Journal of Ophthalmology, 2005; 89: 1413-1417

SLT offers a safe and effective IOP lowering alternative to ALT in patients with OAG on medical therapy. Caution needs to be exercised, however, in patients with heavy degrees of meshwork pigmentation, as these patients are at higher risk for a sustained IOP spike.¹ Two recent papers add to our understanding of important issues: whether SLT can be utilized as first line therapy, and whether it can reduce the burden of medical therapy. Nagar et al. (1010) conducted a randomized prospective study of 90, 180 or 360 degree SLT vs. latanaprost in patients with OAG and ocular hypertension. Success was defined as 20 or 30% IOP lowering from baseline without additional anti-glaucomatous therapy at one year. Demographic characteristics were similar, although the mean baseline IOP in the 90 degree SLT group was lower vs. other groups. This may be significant, as IOP lowering with SLT appears to be dependent on baseline IOP.²

Three hundred and sixty degree SLT was more effective than 180 or 90 degree treatment; 82% of eyes achieved a 20% IOP reduction, and 59% a 30% reduction from baseline. Complications of SLT were more common with 360 degree treatment and included transient early uveitis (50%), ocular pain (39%), and IOP spike of five mmHg or more at 1 hour (27%). Differences in success rates between 360 SLT (n = 44) and latanoprost (n = 39) did not reach statistical significance.

Frances et al.³ conducted a prospective, non-randomized clinical trial and demonstrated that SLT enabled a reduction in medication in OAG over 12 months, while maintaining a pre-determined target IOP. The mean of the differences in medications from baseline was 1.5 at 12 months. Reduction in medications was attained in 52 of 60 eyes (87%) at 12 months. The authors acknowledge that the possibility that tachyphylaxis cannot be totally eliminated.

Three hundred and sixty degree SLT may be an effective alternative to medication as first line therapy; however, additional studies are needed with more patients, assessment of outcome measures such as disc and visual field status, and longer term follow-up before a definitive conclusion can be reached on this issue. Utilizing SLT to reduce the burden of medication in appropriate patients with OAG does seem justified.

Future studies with SLT will need to shed light on other important questions such as whether SLT is repeatable, and whether it is as effective as ALT in pigmentary and pseudoexfoliation related glaucomas.

References

Harasymowycz PJ, Papamatheakis DG, Latina M, De Leon M, Lesk MR, Damji KF. Selective laser trabeculoplasty (SLT) complicated by intraocular pressure elevation in eyes with heavily pigmented trabecular meshworks. Am J Ophthalmol 2005; 139: 1110-1113.
Hodge WG, Damji KF, Rock W, Buhrmann R, Bovell AM, Pan Y. Baseline IOP predicts selective laser trabeculoplasty success at 1 year post-treatment: results from a randomised clinical trial. Br J Ophthalmol 2005; 89: 1157-1160.
Francis BA, Ianchulev T, Schofield JK, Minckler DS. Selective Laser Trabeculoplasty as a Replacement for Medical Therapy in Open-Angle Glaucoma. Am J Ophthalmol 2005; 140: 524–525.

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