The future of glaucoma surgery

Glaucoma surgery is ripe for innovation. In the last few years, there has been a substantial increase in the number of devices approaching commercialization. While not all that is new is necessarily good, the role of these devices in changing glaucoma surgery is equally important in terms of both success and failure. Trabeculectomy, the most commonly performed incisional filtration surgery for glaucoma, is subjective by nature and certainly has risks. As devices aim to standardize glaucoma surgery, specifically subconjunctival filtration surgery, predictability and in turn safety should theoretically improve. This may allow the glaucoma surgeon to intervene earlier in the disease process, prevent more advanced vision loss and potentially decrease the burden of medications

Corneal alterations associated with pseudoexfoliation syndrome and glaucoma: A literature review

A systematic literature review was performed evaluating articles examining the effects of pseudoexfoliation syndrome (PEX) and glaucoma (PEXG) on the cornea with a focus on the corneal endothelium. We searched for articles relevant to pseudoexfoliation syndrome, pseudoexfoliation glaucoma and corneal endothelial cell counts using Pubmed, Google Scholar Database, Web of Science and cochrane Library databases published prior to September of 2016. We then screened the references of these retrieved papers and performed a Web of Science cited reference search. corneal characteristics analyzed included central corneal thickness (ccT), corneal nerve density, endothelial cell density (EcD), polymegathism, and pleomorphism. These parameters were compared in the following populations: control, PEX, PEXG, and primary open angle glaucoma (POAG). Over 30 observational studies were reviewed. Most studies showed a statistically significant lower EcD in PEX and PEXG populations compared to controls. Overall, PEX eyes had a non-statistically significant trend of lower EcDs compared to PEXG eyes. No consistent trends were found when analyzing differences in ccT amongst control, PEX and PEXG groups. For the few studies that looked at corneal nerve characteristics, the control groups were found to have statistically significantly greater nerve densities than PEX eyes, which had significantly greater densities than PEXG eyes. EcD and corneal nerve densities may be potential metrics for risk-stratifying patients with PEX and PEXG. Our literature review provided further evidence of the significant negative influence PEX has on the cornea, worsening as patients convert to PEXG

Fluid dynamics of a novel micro-fistula implant for the surgical treatment of glaucoma,”

PURPOSE. The purpose of this study was to describe the fluidics of a novel non-valved glaucoma implant designed to prevent hypotony and compare the fluidics of this device with two commonly used non-valved glaucoma devices. METHODS. The XEN 45 micro-fistula implant was designed to limit hypotony by virtue of its length and width according to the Hagen-Poiseuille equation. Flow testing was performed using a syringe pump and pressure transducer at multiple flow rates. The pressure differentials across the XEN implant, the Ex-Press implant, and 10 mm of silicone tubing from a Baerveldt implant at a physiologic flow rate (2.5 lL/min) were extrapolated. RESULTS. The XEN 45 achieved a steady-state pressure calculated at 7.56 mm Hg at 2.5 lL/min. At the same flow rate, the Ex-Press device and Baerveldt tubing reached steady-state pressures of 0.09 and 0.01 mm Hg, respectively. CONCLUSIONS. Under flow testing, the XEN micro-fistula implant was able to maintain backpressure above numerical hypotony levels without the use of complex valve systems. This is due to the XEN implant's design, derived from the principles that dictate Newtonian fluids

Safety and efficacy outcomes of the Xen45 Gel Stent use for refractory glaucoma: A surgery series from surgeon trainees at a tertiary teaching hospital

Background: To study the effect of an ab interno gelatin stent (XEN45 Gel Stent, Allergan Inc., Irvine, California, USA) on intraocular pressure (IOP) as placed by glaucoma fellowship trainees in eyes with refractory glaucoma. Methods: A prospective noncomparative study at a tertiary training center on 28 unique eyes undergoing ab interno gelatin stent implantation by glaucoma fellowship trainees. Data was collected at baseline and postoperatively at day 1, week 1, and months 1, 3, 5, and 12. Primary outcome was mean IOP change. Secondary outcomes included change in number of glaucoma medication classes and visual acuity. Safety outcomes included needling rates. Surgical success was defined by achieving ≥20% reduction in IOP with the same or fewer classes of antiglaucoma medications from baseline without the need for secondary surgical intervention and/or stent removal. Results: At baseline, 28.6% (8/28) of the subjects had prior failed incisional glaucoma surgery in a study population that was 54% African-American, with 78% with severe glaucoma (average mean deviation of - 14.58 dB). Thirteen subjects terminated their clinic visits before their 12-month postoperative visit, leaving 15 subjects for end point analysis. Average IOP went from 21.6 mmHg (range 12.0-31.0, SD 6.6) at baseline to 12.5 mmHg (range 7.0-19.0, SD 3.6), a 42.1% reduction ( Conclusions: Compared to the reported literature with experienced ocular surgeons, ab interno gel stent placements by glaucoma fellowship trainees have similar mean IOP, topical medication reduction, surgical success, and needling rates at 12-month follow-up

Immunohistochemical study of epiretinal membranes in patients with uveitis

BACKGROUND: The purpose of this study is to report two cases of idiopathic uveitis with secondary epiretinal membrane (ERM) formation in order to describe histologic and immunohistochemical features that may help distinguish uveitic from idiopathic ERMs. METHODS: The study utilized a clinical case series and histopathological and immunohistochemical findings. RESULTS: There was no identifiable etiology of inflammation in either case. Histology and immunohistochemistry demonstrated a mixture of abundant inflammatory cells, including lymphocytes, histiocytes, plasma cells, and occasional eosinophils, among a stromal matrix composed of glial elements and condensed vitreous, but no retinal pigment epithelium (RPE) was present. The relative proportions of the various inflammatory cell types were assessed with immunohistochemistry, and among the lymphocyte population, T cells predominated over B cells. In one of the cases, there was an abundance of histiocytes, consistent with granulomatous uveitis, which was later confirmed on histology of the enucleated globe. CONCLUSIONS: Idiopathic ERM formation is thought to be secondary to glial cell migration that may require some involvement of RPE cells. The absence of RPE and abundance of inflammatory cells may be used to identify ERMs as secondary to uveitis

An Alternate Technique for Goniotomy: Description of Procedure and Preliminary Results

Purpose: Multiple glaucoma treatment modalities seek to lower IOP by bypassing or removing a portion of the juxtacanalicular trabecular meshwork. These procedures often require expensive implants or specialized surgical instruments. The authors developed a technique for ab interno goniectomy utilizing a standard disposable 25-gauge hypodermic needle. The surgical procedure—termed bent ab interno needle goniectomy (BANG)—and preliminary results are presented here. Methods: A retrospective chart review was performed for all patients who underwent goniotomy using a modified hypodermic needle by one of the three authors between July 2017 and June 2018. The mean and standard deviation pre- and postoperative IOP and the number of glaucoma medications were calculated. The student paired t-test was used to compare pre- and postoperative data. A P-value of <0.05 was considered statistically significant. Results: At postoperative month six, the mean IOP was 13.3 ± 2.5 mmHg (P = 3.6 × 10−7) on 0.5 ± 0.8 topical glaucoma medications (P = 0.01). A ≥20% reduction in IOP was achieved in 73% of patients. Seventy-three percent of patients required ≥1 fewer medication, while 73% of patients required no medications for IOP control. Forty-one percent of those treated achieved IOP ≤12 mmHg. Conclusion: The BANG procedure is a low-cost MIGS technique available to surgeons around the world with preliminary outcomes similar to more expensive alternatives

Intraoperative suprachoroidal hemorrhage during Xen gel stent implantation

Purpose: To report a rare case of intraoperative suprachoroidal hemorrhage during Xen gel stent implantation with accompanying surgical video and subsequent 6-month follow-up. Observations: Our patient required incisional glaucoma surgery after inadequate pressure reduction with four classes of topical medication, methazolamide, and selective laser trabeculoplasty. The patient underwent Xen gel stent implantation and developed an intraoperative suprachoroidal hemorrhage, which was managed in the operating room. The patient recovered his baseline visual acuity with a functioning bleb out to 6 months postoperatively. Conclusions and Importance: Micro-invasive glaucoma surgeries offer a new repertoire of surgical options, purportedly with safer and less invasive techniques. Xen gel stent implantation may be a promising alternative to traditional trabeculectomies and tube shunt implants, providing similar IOP lowering results with potentially lower risk for complications. However, rare and severe complications such as suprachoroidal hemorrhage may still occur. Recognizing a suprachoroidal bleed, particularly intraoperatively, will still be necessary to help minimize the potential vision threatening sequelae often associated with this severe complication

Longitudinal Growth Differentiation Factor 15 (GDF15) and Long-term Intraocular Pressure Fluctuation in Glaucoma: A Pilot Study

Purpose: Growth Differentiation Factor 15 (GDF15) was previously identified as a molecular marker of retinal ganglion cell stress in rodent models of glaucoma and was elevated in the aqueous humor (AH) of patients with primary open-angle glaucoma as a possible risk factor for glaucoma progression. The purpose of this study was to determine whether changes in the AH GDF15 levels were associated with intraocular pressure (IOP) changes in eyes undergoing glaucoma surgery. Methods: Here, we performed a prospective, longitudinal pilot study in nine patients to determine whether changes in AH GDF15 levels from surgery to post-surgery follow-up were associated with IOP fluctuation. An initial AH sample was taken from the peripheral corneal paracentesis during planned glaucoma surgery, and a second sample was taken during an outpatient follow-up visit, approximately six months later. Results: There was a statistically significant correlation between GDF15 fold change and IOP standard deviation (r = 0.87, P = 0.003), IOP range (r = 0.87, P = 0.003), and maximum IOP (r = 0.86, P = 0.003). There was no correlation between the GDF15 fold change and baseline IOP (r = 0.50, P = 0.17), final IOP (r = 0.038, P = 0.92), or mean IOP (r = 0.40, P = 0.28). Conclusion: Our findings in this pilot study suggest that longitudinal changes in AH GDF15 may be associated with IOP fluctuation during the postoperative period. Further studies are necessary to corroborate these findings in a larger patient population and to explore the possibility that AH GDF15 may be used not only to improve treatment algorithms but also as a surrogate endpoint in clinical trials