EyeWorld is the official news magazine of the American Society of Cataract & Refractive Surgery.
Issue link: https://digital.eyeworld.org/i/78788
From left to right: Ramya Swamy, M.D., Luis Vazquez, M.D., Alex Huang, M.D., and Jesse Berry, M.D. Source: Doheny Eye Institute The majority of the studies in the literature have examined the effects of IOP lowering in combina- tion with cataract surgery. The effi- cacy of the iStent alone in lowering IOP in primary open-angle glau- coma is still unknown. Only one small case series by Buchara et al has determined that in secondary open- angle glaucoma, the use of the iStent lowers the burden of treatment with topical medications by one hypoten- sive agent. Other studies, such as one by Samuelson et al, have shown similar results compared to this paper where cataract surgery in combination with iStent placement is superior to cataract surgery alone in lowering IOP greater than 20%. However it is unclear whether this effect is additive since cataract sur- gery alone leads to a significant de- crease. Further studies are needed to determine if use of this minimally invasive device alone in primary open-angle glaucoma can lead to more than a minimal decrease in IOP. The strength of this study lies in its randomized prospective design and 2-year follow-up period with minimal dropout rate (three lost to follow-up in the treatment group and four in the control group). The data suggests that the iStent is a safe device that can be used during cataract surgery as an alternative to lower IOP. There was a total of five cases in the treatment group with stent complications (including stent repositioning, replacement, and ob- struction). Adjunctive iStent place- ment is more likely to maintain IOP <21 mm Hg off hypotensive medica- tions for 1-2 years after surgery than cataract surgery alone. However, the data does not address the efficacy of the iStent compared to other IOP- lowering devices or procedures. And the fact that there was 1 mm Hg dif- ference in IOP at 2 years after sur- gery between groups suggests that the iStent provides only a modest re- duction in IOP. Therefore, the iStent should not be considered in cases where maximum IOP reduction is desired; this agrees with the authors' view that the iStent is suitable for cases of mild to moderate glaucoma. Despite its modest effects on lower- ing IOP, one may speculate that the iStent may blunt spikes in IOP and decrease diurnal variations of IOP. Ultimately, the benefit of adjunctive iStent placement will come down to its long-term assessment on slowing the progression of glaucoma. EW References Mansberger SL, Gordon MO, Jampel H, Bhorade A et al. Reduction in intraocular pressure after cataract extraction: The Ocular Hypertension Treatment Study. Ophthalmology 2012 May 16. EPUB ahead of print. Buchacra O, Duch S, Milla E, Stirbu O. One year analysis of the iStent trabecular microbypass in secondary glaucoma. Clinical Ophthalmology, 2011;5:321-6. Samuelson TW, Katz LJ, Wells JM, Duh YJ. Randomized evaluation of the trabecular micro-bypass stent with phacoemulsification in patients with glaucoma and cataract. Ophthalmology. 2011:118(3):459-67. Contact information Quiros: pquiros@usc.edu