Abstract
Purpose: :
To determine the effect of prostaglandin analog (PGA) use on outcome after selective laser trabeculoplasty (SLT). PGA's lower intraocular pressure (IOP) by increasing uveoscleral (US) outflow via a PGA–induced increase in matrix metalloproteinase (MMP’s) activity in the US system. MMP’s are known to degrade components of the extracellular matrix (ECM). Remodeling of US ECM by MMP's may increase outflow facility. Although trabecular meshwork (TM) cells also express MMP’s, their activity is not influenced by PGA's under normal physiologic conditions. After laser trabeculoplasty (LT), MMP activity is increased in the TM. Increased MMP activity and remodeling of the TM ECM may play a role in the IOP–lowering effects of LT. The increase in TM MMP activity following LT may be derived from physiologically–altered TM cells or from macrophages. It is unknown whether TM MMP activity post–LT is sensitive to PGA's and how PGA application would affect postoperative outcome.
Methods: :
Records of 86 eyes with open angle glaucoma who underwent SLT (59.6 +/– 6.5 laser spots over180 degrees, power: 1.1+/–0.1 mJ) were reviewed. Eyes were categorized according to use of PGA's (n=53), or other classes of glaucoma drops (n=33) pre and post–SLT. IOP was measured pre–SLT (baseline IOP=avg. of IOP on last 2 visits), 1 week and 1 month post–SLT. Average IOP (mm Hg) decrease and average percent IOP decrease relative to baseline were compared between groups. Success was defined as a 20% or greater, or a 3 mm Hg or greater IOP decrease relative to baseline at 1 month post–SLT.
Results: :
Baseline IOP did not differ (p=NS) between PGA (17.9+/–3.8 mm Hg) and non–PGA (17.5+/–4.3 mm Hg) users. At 1 month post–SLT, average IOP decrease was greater (p<0.03) in the PGA users (3.4+/–3.6 mm Hg) compared to non–PGA users (1.7+/–3.1 mm Hg) and average percent IOP decrease was greater (p<0.03) in PGA users (17.3 %) compared to non–PGA users (8.4 %). There were no significant differences in average IOP decrease (3.1+/–3.8 mm Hg v 2.9+/–2.1 mm Hg) or percent IOP decrease (15.1 % v 15.2 %) between PGA users and non–users, respectively, 1 week post– SLT. 49% of PGA users (26/53) had a 20%, or greater decrease in IOP compared to 24% of non–users (8/33) 1 month post–SLT (p<0.02). 52% of PGA users (28/53) had an IOP decrease of 3 mmHg or greater compared to 33% of non–users (11/33) 1 month post–SLT (p<0.05).
Conclusions: :
PGA use results in a significantly greater average and percentage decrease in IOP 1 month post–SLT. PGA use is associated with a significantly greater likelihood of treatment success at 1 month post–SLT. The increased effect from SLT in PGA treated eyes may be due to enhanced TM MMP activity postoperatively.
Keywords: intraocular pressure • pharmacology • clinical (human) or epidemiologic studies: outcomes/complications