Pericytes are specialized mural cells located at the abluminal surface of capillary blood vessels, embedded within the basement membrane. In the vascular network these multifunctional cells fulfil diverse functions, which are indispensable for proper homoeostasis. They serve as microvascular stabilizers, are potential regulators of microvascular blood flow and have a central role in angiogenesis, as they for example regulate endothelial cell proliferation. Furthermore, pericytes, as part of the neurovascular unit, are a major component of the blood-retina/brain barrier. CNS pericytes are a heterogenic cell population derived from mesodermal and neuro-ectodermal germ layers acting as modulators of stromal and niche environmental properties. In addition, they display multipotent differentiation potential making them an intriguing target for regenerative therapies. Pericyte-deficiencies can be cause or consequence of many kinds of diseases. In diabetes, for instance, pericyte-loss is a severe pathological process in diabetic retinopathy (DR) with detrimental consequences for eye sight in millions of patients. In this review, we provide an overview of our current understanding of CNS pericyte origin and function, with a special focus on the retina in the healthy and diseased. Finally, we highlight the role of pericytes in de- and regenerative processes.

ImportanceThe transscleral XEN Glaucoma Gel Microstent (XEN‐GGM, Allergan Plc., Parsippany, New Jersey) is implanted by a minimally invasive ab interno technique.BackgroundThe present study aims to assess the long‐term clinical outcomes in patients after XEN‐GGM implantation.DesignThis prospective, non‐randomized, multi‐centred study was conducted in three countries (Austria, Canada and Germany).ParticipantsSixty‐four consecutive eyes of 64 patients with open angle glaucoma received the XEN‐GGM (63 μm) without Mitomycin C. Thirty‐five (55%) were solo procedures, and 29 (45%) were combined with cataract surgery.MethodsVisits were planned at baseline, 6 months, 1, 2, 3 and 4 years postoperatively.Main Outcome MeasuresThe main outcome measures were mean intraocular pressure (IOP), mean number of IOP lowering medication. Secondary outcome parameters were: visual acuity, visual fields and complete surgical failure (defined as presence of a secondary IOP lowering procedure or loss of light perception) at 4 years, postoperatively.ResultsMean best‐medicated baseline IOP was 22.5 ± 4.2 mmHg and decreased significantly to 13.4 ± 3.1 mmHg 4 years postoperatively (−40%, n = 34, P < 0.001). Mean number of IOP lowering medication decreased significantly from 2.4 ± 1.3 preoperatively to 1.2 ± 1.3 (−50%, n = 34, P < 0.001) postoperatively. Visual field mean deviation showed no significant change between preoperative and postoperative examinations. Complete surgical failure rate per year was 10%.Conclusions and RelevanceThe XEN‐GGM resulted in lower IOP and a reduction in medications from baseline over 4 years of follow‐up. There was no detectable decrease in visual fields over the study. The surgical failure rate is comparable to other filtration surgeries.

Dr. Grabner was reimbursed for travel expenses from Acufocus. Dr. Riha is a consultant to Acufocus. No other author has a financial or proprietary interest in any material or method mentioned.

Bleb appearance after XEN surgery seems to be different to classic trabeculectomy literature. The present data suggest correlation of IOP and surgical long-term success with bleb morphology in AS-OCT. Prevalence of small diffuse cysts is directly associated with lower IOPs, while cystic encapsulation at 3 months predicts higher surgical failure.

Purpose: The outer stent lumen can be located either deeper (in or under Tenon's layer) or more superficially in the conjunctival stroma after the transscleral XEN Glaucoma Gel Microstent (XEN-GGM; Allergan Plc., USA) implantation. The present study aimed to investigate the effect of the postoperative conjunctival implant position on surgical success and intraocular pressure (IOP) after XEN-GGM. Methods: Prospective data from 66 consecutive open-angle glaucoma eyes of 54 patients were collected preoperatively and 1 and 2 weeks, and 1, 6 and 12 months postoperatively. The layer of implantation was determined in the first month postoperatively as intra-and subtenon or intraconjunctival depending on the location of the outer lumen of the stent in OCT (Visante OCT; Zeiss, Germany). Primary outcome measures were differences in relative IOP reduction at 12 months between the two groups. Further, complete and qualified surgical success, number of secondary needlings and number of IOP-lowering medications and absolute IOP were assessed. Results: Relative IOP reduction was higher in intra-and subtenon group (n = 37/ 66, 56%) at week 1 (À54% versus À19%, p < 0.001), week 2 (À39% versus À21%, p = 0.02), month 1 (À42% versus À28%, p = 0.035) and month 12 (À39% versus À24%, p = 0.024). The mean absolute IOP was lower in intra-and subtenon group at week 1 (10.8 [95%CI,.0] mmHg, p < 0.001) and months 12 (13.9 [95%CI,] mmHg, p = 0.041). At month 6, a lower burden for IOP-lowering medication was shown for the intra-and subtenon group (0.2 AE 0.5 versus 1.0 AE 1.1, p = 0.034). The mean number of secondary needlings, which were done in 47/66 (71%) of the eyes, was lower in the intra-and subtenon group in the first year (1.9 AE 1.7 versus 1.2 AE 1.2, p = 0.03). Qualified surgical success was higher in the intra-and subtenon group (90% versus 61%, p = 0.01) after 1 year. Conclusion: The present study demonstrates a higher efficacy achieved with lower secondary needling rates in deeper implant positions in conjunctiva after XEN-GGM.

No author has a financial or proprietary interest in any material or method mentioned.

Based on previous findings of visual field defects after LASIK, and as a consequence of the present study, it seems feasible to design patient interfaces in a more physiologic manner to prevent high IOPs during refractive procedures.

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