Better LPI Results Possible with AS-OCT Angiography vs. Slit Lamp

Current practice with LPI has providers use slit lamp biomicroscopy to select iris crypts on the superior region, but this does not provide clinicians with information on the extent of vascularization within the crypts, which OCT can. Photo: Lin J, et al. Transl Vis Sci Technol. 2025;14(11):2. Click image to enlarge. Primary angle-closure suspect patients often receive laser peripheral iridotomy (LPI), commonly performed at the slit lamp. LPI may also be conducted with anterior segment OCT angiography (AS-OCTA). Researchers evaluated the differences between the two approaches in a recent paper appearing in Translational Vision Science & Technology.To study both options, the right eyes of 30 patients suspicious for primary angle-closure were assigned to the AS-OCTA group, while the left eyes underwent LPI guided by slit lamp. In the OCT group, the peripheral site with the sparsest iris vasculature seen on AS-OCTA images was selected; conversely, for the slit lamp subjects, iridotomy site was chosen based on presence of an iris crypt seen by clinicians. Both groups were then compared for incidence of anterior chamber bleeding, anterior chamber particle (ACP) index, mean angle opening distance (AOD750) and anterior chamber depth (ACD) as measured with the OCT images, as well as vessel density and perfusion area also seen with OCT.Anterior chamber bleeding occurrence was much lower in the AS-OCTA group at 13.3% vs. 43.3% in the slit-lamp group. Although OCT was employed before LPI and also at one hour, one day and one week after procedure, an observable difference only existed one hour after, with the AS-OCTA group showing lower vessel density, perfusion area and ACP, but a larger AOD750 when compared with the slit-lamp guided group. Essentially, using AS-OCT reduced anterior chamber inflammatory response and local vascular changes around the site, and this method also returned a larger angle opening in the peripheral chamber.The authors expand upon their research, citing that the AS-OCTA images yielded clearer views of the iris vasculature, in turn being guided to identify LPI sites that were least vascularized to minimize bleeding risk. With the current approach using the slit lamp, if no iris crypts are present in the superior region or any region, clinicians have a difficult time identifying an adequate site for LPI.After this procedure, acute and transient intraocular pressure (IOP) elevation is the most cited complication, with a ratio of IOP spike reported to be up to 10%. The current study saw more IOP spikes in the slit lamp group than AS-OCTA one hour after (nine eyes vs. seven). The authors relay that this could be secondary to bleeding, as it induces elevated IOP by releasing blood cells and debris which impede aqueous drainage. What’s more, ACP was much lower with the OCT group as well after one hour, indicating fewer inflammatory cells, blood cells and iris pigmentary debris.In clinical settings, the authors believe that “the incidence of anterior chamber bleeding could be lowered by knowing the iris vessel layout measured using AS-OCTA before the LPI procedure. AS-OCT/OCTA may also be used for immediate assessment and follow-up of LPI treatment efficacy and anterior chamber responses.”In general, they add that “this study shows that the AS-OCTA-guided LPI procedure could bridge advanced imaging technology and clinical glaucoma management.”Click here for the journal source. Lin J, Mao J, He M, Zhang Y, Nie L. AS-OCT-guided versus slit lamp-guided laser peripheral iridotomy for primary angle-closure suspect patients: a short-term result. Transl Vis Sci Technol. 2025;14(11):2. This article was developed by the editorial staff in conjunction with experts in the field. In the process, AI may have been among the editorial tools used to meet the goals of human editors, who approved all content.