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William S Kass, Albert S Khouri; Safety and Outcomes After Trabecular Microbypass in Patients with Prior Laser Treatment. Invest. Ophthalmol. Vis. Sci. 2019;60(9):3728.
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© ARVO (1962-2015); The Authors (2016-present)
iStent, an injectable version of Minimally Invasive Glaucoma Surgery (MIGS) provides an outflow for aqueous humor through the trabecular meshwork into the canal of schlemm. This has been shown to provide modest reductions of intraocular pressure (IOP) and medication burden in patients with moderate primary open angle glaucoma (POAG). Many patients who receive iStents have had prior laser procedures which physically alter the trabecular meshwork. We identified patients who had received iStents following prior laser therapy and compared their results to patients without prior laser treatment.
A retrospective review of 56 subjects who had received iStents met the eligibility criteria and were selected for evaluation. 24 patients (27 eyes) received selective laser trabeculoplasty (SLT) before getting an iStent were compared to 32 patients (34 eyes) who received an iStent without prior laser treatment. Intraocular pressure, number of medications and visual acuity were evaluated at baseline, 1 day, 1 week, 1 month, 6 months and 12 months post-operatively.
61 eyes of 56 patients were included. The initial average initial IOP was 17.98+/-5.80 for the group with prior SLT and 17.32+/-4.03 for the group without. By the 6 month timepoint the groups had achieved comparable reductions in IOP of 14.48+/-4.31 and 14.84+/-2.19 respectively. At each timepoint following surgery the –SLT group had a significantly lower IOP than baseline with the exception of the 1 week post-operative time point (P-value between 0.0043 and 0.0247 Mann-Whitney test 95% CI). The group of patients with prior SLT showed an average reduction of pressure following iStent placement however, the reduction only became significant at the 6 month timepoint and beyond (P-value between 0.0442 and 0.0402 Mann-Whitney test 95% CI). Both groups of patients were prescribed to a comparable number of medications at each timepoint.
MIGS has provided a new option to safely reduce pressures in moderate POAG, however it is frequently implemented after other pressure reducing procedures. It is important to explore if these prior techniques impact the efficacy of these devices. The preliminary results of our study indicate that there is no significant difference in the function of iStent between eyes with and without prior laser treatments, however more data is needed.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.
Comparison between groups.
Change within group from baseline.
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