Choroidal blood flow in glaucoma patients in conditions of ophthalmic hypertension and compensated intraocular pressure

Purpose. To evaluate changes in chorioretinal blood flow in the early postoperative period after non-penetrating deep sclerectomy (NPDS) in patients with primary open-angle glaucoma (POAG) and determine their relationship with the level of Goldman intraocular pressure (IOPg). Material and methods. The study included 36 patients with primary open-angle glaucoma of stage 1–2, with an IOP level above 21 mm Hg at the maximum hypotensive mode. All patients underwent glaucoma surgery (NPDS) by a single surgeon. IOP measurement was performed by dynamic bidirectional applanation using the Ocular Response Analyzer (Reichert Inc., USA). When evaluating the results, the Goldman IOP indicators (IOPg) were taken into account. The ophthalmic examination included optical coherence tomography of the optic disk and macular area, as well as assessment of the blood flow of these structures using optical coherence tomography in angio mode (OCTA) (RTVue XR Avanti, Optovue Inc., США). The thickness of the choroid was estimated using crossline protocols performed through the center of the fovea in the horizontal and vertical meridians. Results. Based on the assessment of changes in the indicators of ocular blood flow in the postoperative period, all patients were divided into 2 groups: group 1 – 28 patients (28 eyes) who showed improvement in OCTA after surgery, group 2 – 8 patients (8 eyes) who, according to OCTA data, showed no changes or decreased indicators of ocular blood flow after surgery. In patients of both groups, the level of IOPg before surgical treatment was comparable. On the 3rd day after NPDS IOPg in the group 1 decreased to 9.3 ± 1.2 mm Hg, while in group 2 hypotonia was detected (IOPg 3,6 ± 1,3 mm Hg, р = 0,001). All patients showed an increase in the thickness of the choroid in the central area and peripapillary after glaucoma surgery: in group 1 by 23 and 26 %, in group 2 by 48 and 62 %, respectively. In group 2 there was a significant increase in the large vessels caliber and the vascular membrane thickness as a whole to 115.4 % of the original. In group 1 patients, against the background of normalization of ophthalmotonus, there was a tendency to increase the capillary density of the superficial vascular plexus (from 40.9 ± 5.38 to 41.1 ± 3.56 %) and the deep vascular plexus (from 43.9 ± 6.1 to 44.7 ± 5.97 %). There was a positive trend of increasing capillary density in the radial peripapillary plexus (from 46.6 ± 8.9 to 47.2 ± 9.0 %). In patients of group 2, capillary density significantly decreased: from 39.9 ± 3.64 to 37.6 ± 2.48 % in the superficial vascular plexus and from 41.1 ± 4.72 to 38.7 ± 3.51 % in the deep vascular plexus. Conclusion. A decrease in the level of ophthalmotonus after NPDS was accompanied, in most cases, by a moderate increase in the thickness of the choroid and a tendency to improve blood flow in the retinal plexuses. Postoperative hypotension is characterized by dysregulation of choroidal blood flow, decompression violation of topographic relationships, which generally leads to the formation of choroidal effusion and vascular detachment.

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