Faculty Bibliography

Purpose/UNASSIGNED:To compare the safety and efficacy of two different techniques for implantation of the XEN Gel Stent, a minimally invasive surgical device for the treatment of refractory glaucoma. Methods/UNASSIGNED:A retrospective chart review of eyes that received ab interno or ab externo XEN Gel Stent placement from February 2017 to October 2019 was conducted. A single surgeon (NMR) performed all operations. Eyes that received the XEN implant concomitant with a glaucoma drainage device insertion or that were lost to 6-month follow-up were excluded. Intraocular pressure (IOP) change, change in glaucoma medications, frequency of slit lamp revision procedures, and frequency of secondary glaucoma surgeries were the primary outcomes compared between groups. Results/UNASSIGNED:Fifty eyes that underwent ab interno placement and 30 eyes that underwent ab externo placement were studied. The ab interno cohort demonstrated a mean IOP reduction of 8.4 ± 1.7 mmHg (28.6% decrease) by 12 months, compared to a mean reduction of 12.8 ± 3.0 mmHg (40.1% decrease) in the ab externo group (p = 0.208). Mean reduction in medication use was 1.81 ± 0.29 medications in the ab interno group and 1.86 ± 0.37 in the ab externo group (p = 0.913). By 12 months, 58% of ab interno eyes had required 5-fluorouracil injection compared to 36.7% of ab externos (p = 0.105). Bleb needling was applied to 42% and 26.7% of the eyes, respectively (p = 0.231). A second glaucoma surgery was necessary for 20% of the ab interno cohort and 10% of the ab externo cohort (p = 0.351). Conclusion/UNASSIGNED:There were no differences in outcomes between ab interno and ab externo placement of the XEN Gel Stent. Both approaches are safe and effective for lowering IOP.

The Xen Gel Stent lowers intraocular pressure by shunting aqueous humor to the subconjunctival space. While published studies include both open conjunctiva and closed conjunctiva approaches, most publications feature a closed conjunctiva, ab interno approach. While this approach is widely used, other approaches may be preferred for some patients. This paper provides details on surgical steps and tips for enhancing outcomes for an open conjunctiva technique for the implantation of the Xen Gel Stent, as well as reasoning as to when this approach should be used.

PRE[COMBINING ACUTE ACCENT]CIS:: Cortical response to low contrast stimuli, as measured by isolated-check visual evoked potential (icVEP) technology, has the potential to provide functional assessment that may complement standard achromatic perimetry in assessing glaucomatous change.

PURPOSE/OBJECTIVE:This review will provide an update on surgical techniques, outcomes, and complications for two new translimbal bleb-forming surgical glaucoma devices. RECENT FINDINGS/RESULTS:The XEN Gel Microstent and PreserFlo MicroShunt comprise a category of subconjunctival microinvasive glaucoma surgery developed with the aim of improving the predictability and safety profile of bleb-forming procedures. Both devices are made of noninflammatory material which limits postsurgical inflammation and scarring and have a valve-less intrinsic flow-limiting design, which decreases the risk of hypotony. There are various techniques of implantation for the XEN Gel Microstent each with their own advantages and disadvantages. SUMMARY/CONCLUSIONS:These devices have demonstrated promising outcomes in early experimental literature with similar intraocular pressure-lowering effects to traditional incisional surgery such as trabeculectomy or tube shunt surgery, but with fewer risks. Future randomized, prospective studies should be done to compare these gel stents and microshunts both to each other and to other traditional glaucoma surgeries.

Purpose : Initial outcome reports for Xen gel stent implantation surgery have varied, with some groups reporting high rates of bleb needling. Surgical methods of implantation have also varied between ab interno and ab externo (sub-Tenon) approaches. This study examined bleb morphology and rates of surgical success, as well as rates of bleb failure and needling following sub-Tenon Xen implantation. Methods : Medical records of 24 patients (26 eyes) who underwent sub-Tenon Xen implantation from 8/2013-12/2018 were retrospectively reviewed. Postoperative intraocular pressure (IOP) and number of glaucoma medications were analyzed at 1, 3, 6, 9 and 12 months. Surgical success was defined as IOP<21 and >=5 mmHg with IOP reduction >=20% from baseline at 2 consecutive follow-ups (>3 months) without loss of vision or need for reoperation. Bleb morphology and characteristics were analyzed by anterior segment optical coherence tomography (AS-OCT, Topcon DRI OCT version 1.1.1). Results : 92.3% (24/26) of eyes achieved surgical success (61.5% without medication, 30.7% with medication). Mean preoperative IOP was 28.1+/-7.8 mmHg on 3.5+/-0.9 glaucoma medications. Mean IOP at postoperative month 6 (n=24) and 12 (n=14) was 13.3+/-5.5 mmHg (p<0.01) and 13.4+/-2.4 mmHg (p<0.01) respectively, on 0.4+/-0.8 (p<0.01) and 0.2+/-0.4 (p<0.01) medications. Complications, all on postoperative day 1, included hypotony (27%) and hyphema (23%). 3 eyes (12%) required needling. In the early postoperative period (<3 months), bleb morphology was characterized by multiple sub-conjunctival microcysts. At intermediate (6-12 months) and late (>24 months) timepoints, bleb morphology was characterized by multiple internal parallel layers of aqueous flow and uniform patterns. Bleb height was higher in late and intermediate blebs than in early blebs. All functional blebs showed the presence of a posterior episcleral fluid (PEF) lake, which was taller in intermediate and late blebs. All failed blebs showed high reflectivity with absence of aqueous flow at the distal end of the stent. Conclusions : The sub-Tenon (open) technique of Xen gel stent implantation can provide significant IOP control with favorable bleb morphology and a low rate of postop bleb needling. A diffuse PEF lake on AS-OCT is consistent with surgical success. Further research, including prospective study, is needed to determine whether the sub-Tenon approach outperforms other methods

Purpose : The presence of s zone peripapillary atrophy (PPA) has been associated with glaucoma. We performed a retrospective longitudinal study to evaluate s zone PPA area as a predictor for glaucomatous structural and functional progression. Methods : Subjects with glaucoma and >4 visits were included. Subjects had Humphrey visual field (Zeiss, Dublin, CA) testing, spectral-domain OCT (Cirrus HD-OCT; Zeiss) optic nerve head (ONH) and macula scans. s zone PPA was manually delineated on the baseline en face ONH scan as the area contiguous with the optic disc with the presence of hyper-and hyporeflectivity. Mixed effects linear models accounting for intra-subject correlation, follow-up time, scan's signal strength and ethnicity, were performed to determine if baseline PPA area was associated with glaucoma severity. Subsequent models incorporating the interaction term between time and baseline PPA area were performed to determine if baseline PPA area affected the rate of change in parameters of glaucoma over time. Results : 81 eyes (56 subjects) aged 62.8+/-14.1 years with an average follow-up time 3.9+/-1.3 years were analyzed. PPA was significantly associated with mean deviation (MD), visual field index (VFI), and inferior retinal nerve fiber layer (RNFL), (p=0.033, 0.038, and 0.034, respectively), but not with average RNFL, or macular ganglion cell inner plexiform layer (GCIPL) global and sectoral measurements and ONH parameters. No significant association was detected between s zone PPA area and the rate of progression for any parameter except for VFI (p =0.035). Conclusions : Although baseline s zone PPA area is associated with some indicators of glaucoma severity, it is not a significant predictor of the rate of glaucomatous progression (except for VFI)

PURPOSE/OBJECTIVE:To describe a surgical technique for treating persistent hypotony after Baerveldt glaucoma implant (BGI) surgery. METHODS:The medical records of ten patients with persistent postoperative hypotony who underwent truncation of one or both wings of a previously placed BGI, combined with external ligation of the tube using a polypropylene suture, were retrospectively reviewed. RESULTS:All 10 eyes that underwent BGI truncation and placement of a single, external, non-absorbable (polypropylene) tube ligature exhibited resolution of hypotony within 24 hours and resolution of choroidal effusions within the first 2 postoperative weeks. Median time interval between primary BGI surgery and truncation was 5 months (range, 1.5▒mo to 8▒y). Median post-revision follow-up time was 12 months (range, 5▒mo to 16.2▒y). The mean preoperative intraocular pressure (IOP) was 2.1±1.0▒mm Hg, and the mean IOP rose to 29.2±13.9▒mm Hg on postoperative day 1. Mean IOP at week 1, month 1, and month 3 was 20.5±10.4▒mm Hg, 19.7±11.8▒mm Hg, and 18.0±8.2▒mm Hg, respectively, using an average of 1.4±1.4 glaucoma medications at postoperative month 3. Ligature release after BGI revision was performed in 9 (90%) of the 10 patients. Median time to ligature release was 1.5 months (range, 3▒wk to 4▒y). There was no recurrence of hypotony in any of these patients. At most recent follow-up, the mean IOP was 12.9±6.0▒mm Hg on an average of 1.5±1.3 glaucoma medications. Five patients demonstrated improvement in visual acuity from their pre-revision best corrected visual acuity. CONCLUSIONS:Truncation of one or both wings of a BGI and complete closure of the tube with non-absorbable, but releasable, suture ligature is an effective and safe method for reversing persistent postoperative hypotony while maintaining IOP control.

Purpose : To analyze changes in bleb morphology over time post-ab interno XEN Gel stent (Aquesys Inc., California, USA) implantation aided by conjunctival peritomy. Methods : Patients who underwent successful XEN Gel stent implant [defined as >=20% reduction in intraocular pressure (IOP)] were included in the study. They were grouped according to their postoperative follow up duration: short-term (up to 3 months, group A), intermediate (>3 months-12 months, group B) and long-term (>12 months, group C). Bleb morphology was studied using the anterior segment feature of the Triton Swept Source Optical Coherence Tomography (AS-OCT). Twelve radial scans (16mm) centered over the bleb area were obtained. The bleb characteristics noted were: bleb wall thickness, internal height, and degree of internal reflectivity, which was classified as low, medium, high according to the color scale on AS-OCT. Bleb morphology was further characterized as uniform, subconjuctival separation, microcytic multiform and multiple internal layer. Results : Images were obtained on a total of 23 eyes. There were 9, 10 and 4 eyes each in Group A, B and C with the mean age of patients being 74.22+/-6.5, 69.55+/-8.50 and 61.5+/-3.41 years respectively. At a mean follow-up of 0.9+/-0.9 months, AS-OCT showed a bleb wall thickness of 115.67+/-22.3mum, bleb height of 547.56+/-230.77mum with the presence of a posterior episcleral fluid (PEF) lake of 179.0+/-106.85mum in group A. Thereafter, the bleb wall thickness and height showed a decline to 106.80+/-31.09mum(p=0.48) and 534.90+/-181.99mum(p=0.89) at a mean follow-up of 6.45+/-2.41 months in group B and 98.50+/-42.30mum(p=0.48) and 492.50+/-66.32mum(p=0.52) at a mean follow-up of 39.95+/-11.34 months in group C respectively, with a simultaneous increase in the PEF lake to 381.30+/-286.17mum in group B(p=0.06) and to 514.75+/-231.21mum in group C(p=0.05). Most of the blebs showed medium internal reflectivity (83%) and high bleb wall reflectivity (61%). The most common morphology was subconjuctival separation (67%) in the early period (Fig.1) which gradually remodeled to multiple internal layer (75%) in the late follow-up (Fig.2). Conclusions : AS-OCT can be the imaging of choice in assessing blebs with newer implants and considering variations in technique. This study characterizes features of bleb evolution in Xen implantation with conjunctival peritomy