Episcleral Venous Fluid Wave in the Living Human Eye Adjacent to Microinvasive Glaucoma Surgery (MIGS) Supports Laboratory Research: Outflow is Limited Circumferentially, Conserved Distally, and Favored Inferonasally

'Intraoperative predictors for clinical outcomes after microinvasive glaucoma surgery"

PURPOSE

To evaluate the clinical applicability of intraoperative predictors for surgical outcomes after gonioscopy-assisted transluminal trabeculotomy (GATT) and microincisional trabeculectomy (MIT).

METHODS

Consecutive patients with primary, or secondary glaucoma (trauma, aphakic, or status post-retinal surgeries) with uncontrolled IOP>21mm Hg, who were scheduled to undergo GATT or MIT with or without significant cataract surgery, at a tertiary eye centre in East India between September 2021 to March 2023, were included. All surgeries were done by a single surgeon. Blanching and Trypan blue (0.4%) staining after intracameral injection using a 25 canula, were analysed in each video. The extent/pattern of blanching and blue staining in each eye was analysed objectively using an overlay of a circle with 12 sectors and a protractor tool to quantify the degrees or quadrants of blanching/staining. Multivariate regression was used to identify predictors for surgical success or the need for medications after surgery.

RESULT

Of 167 eyes that were included (male: female- 134: 33), 49 eyes and 118 eyes underwent GATT and MIT, respectively, with 81 of 167 eyes undergoing concurrent cataract surgery. All eyes had a significant reduction in the number of medications after surgery. Blanching was seen in 154 of 167 eyes in a mean of 2±1.8 quadrants with 41% of eyes showing a blanching effect in >3 quadrants. Of 99 of 167 eyes where Trypan blue staining was assessed, staining in a venular, diffuse haze, or reticular pattern of staining was seen in 73 eyes, 26 eyes showed blue staining in >2 quadrants, with 16% staining in >3 quadrants. Surgical success was not predicted by the quadrants of blanching, blue staining, or other clinical variables (age, visual field, baseline intraocular pressure, type of surgery). The variables significantly predicting the need for medications included blanch (r = -0.1, p = 0.03), and blue staining (r = -0.1, p = 0.04) in <2 quadrants.

CONCLUSIONS

Blanching and Trypan blue staining in >2 quadrants after GATT or MIT can serve as surrogate predictors for the need for medications. However more studies are mandated to find predictors for surgical success after GATT or MIT.

Effects of Ripasudil on Open-Angle Glaucoma after Circumferential Suture Trabeculotomy Ab Interno

We evaluated the effects of ripasudil on the distal aqueous outflow tract in patients with open-angle glaucoma (OAG) who underwent a 360° suture trabeculotomy ab interno followed by ripasudil treatment beginning 1 month postoperatively. We compared 27 of these patients, by using propensity score analysis, with 27 patients in a matched control group who had no ripasudil treatment. We assessed the changes in the mean intraocular pressure (IOP) and the relationship between the IOP changes and background factors. All eyes had a complete 360° Schlemm’s canal incision and phacoemulsification. The mean IOP at 1 and 3 months after ripasudil administration were significantly reduced by −1.7 ± 1.9 mmHg (p < 0.0001) and −1.3 ± 2.3 mmHg (p = 0.0081) in the ripasudil group, respectively, but IOP in the control group was not significantly reduced. The IOP reduction was significantly associated with the IOP before ripasudil treatment (p < 0.001). In conclusion, the use of ripasudil for patients with OAG after circumferential incision of the Schlemm’s canal produced significant IOP reductions. Ripasudil may affect the distal outflow tract, thereby leading to the IOP reduction.

Intraocular Pressure After Cataract Surgery Combined With Ab Interno Trabeculectomy Versus Trabecular Micro-bypass Stent: An Intrasubject Same-surgeon Comparison

PRECIS

Combining Trabectome or iStent with phacoemulsification equally reduces intraocular pressure (IOP) and IOP-lowering medication burden during a 24-month follow-up, with a possible advantage to the Trabectome in the early postoperative period.

PURPOSE

Intrasubject same-surgeon comparison between phacoemulsification combined with Trabectome (Phaco/Trabectome) versus one first-generation iStent (Phaco/iStent).

SETTINGS

Private glaucoma and cataract practice.

DESIGN

This is a retrospective interventional case series.

METHODS

Data collected at 3 to 4 and 20 to 24 hours and up to 30 months following Phaco/Trabectome in 1 eye and Phaco/iStent in the contralateral eye in patients with bilateral visually-significant cataract and open-angle glaucoma. Evaluations included IOP, intraocular pressure-lowering medications (IOPmeds), visual acuity, and complications.

RESULTS

Forty-five patients (90 eyes) were identified (age 76.5, 57 to 95 y). At 3 to 4 hours, IOP was above baseline in 12 and 13 eyes following Phaco/Trabectome and Phaco/iStent, respectively, but the degree of IOP elevation was smaller (P=0.048) following Phaco/Trabectome: 4.3 mm Hg, 2.0 to 6.6 mm Hg (95% confidence interval) versus Phaco/iStent: 8.7 mm Hg, 3.8 to 13.6 mm Hg. At 20 to 24 hours, compared with baseline, IOP was significantly lower after Phaco/Trabectome (P=0.004) but not after Phaco/iStent (P=0.14) although the rate of hyphema was higher following Phaco/Trabectome (12/45 vs. 2/45 eyes, P=0.007). IOP reduction from baseline at 3 to 4 hours was significantly larger (P=0.020) in the 21 eyes with hyphema: -3.9, -6.4 to -1.4 versus the 69 eyes without hyphema: -0.3, -2.0 to +1.4. At 1, 6, 12, and 24 months, IOP and number of IOPmeds were similar and significantly lower compared with baseline following either procedure. No complications were encountered in either group.

CONCLUSIONS

Combined phacoemulsification with either Trabectome or first-generation iStent similarly lowers IOP and IOPmeds burden at 1, 6, 12, and 24 months following surgery. The Trabectome may have an advantage in lowering IOP faster and lessening the degree of IOP elevations in the early postoperative period.

The Effects of Trabecular Bypass Surgery on Conventional Aqueous Outflow, Visualized by Hemoglobin Video Imaging

PRECIS

Hemoglobin Video Imaging (HVI) provides a noninvasive method to quantify aqueous outflow (AO) perioperatively. Trabecular bypass surgery (TBS) is able to improve, and in some cases re-establish, conventional AO.

PURPOSE

The purpose of this study was to use HVI to illustrate and quantify effects of TBS on AO through the episcleral venous system.

DESIGN

This is a prospective observational cohort study.

PARTICIPANTS

Patients were recruited from Sydney Eye Hospital, Australia. The study included 29 eyes from 25 patients, 15 with glaucoma and 14 normal controls. TBS (iStent Inject) was performed on 14 glaucomatous eyes (9 combined phacoemulsification/TBS and 5 standalone TBS). Cataract surgery alone was performed on the remaining eye from the glaucoma group and 2 eyes from the control group.

METHODS

We used HVI, a novel clinic-based tool, to visualize and quantify AO perioperatively during routine follow-up to 6 months. Angiographic blood flow patterns were observed within prominent aqueous veins on the nasal and temporal ocular surface. Aqueous column cross-section area (AqCA) was compared before and after surgery.

MAIN OUTCOME MEASURES

AqCA, number of aqueous veins, intraocular pressure (IOP) before and after surgery, and number of IOP-lowering medications.

RESULTS

Patients with glaucoma had reduced AqCA compared with normal controls (P=0.00001). TBS increased AqCA in 13 eyes at 1 month (n=14; P<0.002), suggesting improved AO. This effect was maintained at 6 months in 7 eyes (n=9, P≤0.05). All patients with unrecordable AO before surgery (n=3; 2 standalone TBS, 1 combined cataract/TBS) established measurable flow after TBS. IOP and/or medication burden became reduced in every patient undergoing TBS. Cataract surgery alone (n=3) increased AqCA in nasal and temporal vessels at 4 weeks after surgery.

CONCLUSIONS

HVI provides a safe method for detecting and monitoring AO perioperatively in an outpatient setting. Improvement of AO into the episcleral venous system is expected after TBS and can be visualized with HVI. TBS is able to improve, and in some cases re-establish, conventional AO. Cataract surgery may augment this. Some aqueous veins were first seen after TBS and these patients had unstable postoperative IOP control, which possibly suggests reorganization of aqueous homeostatic mechanisms. HVI may confirm adequacy of surgery during short-term follow-up, but further work is required to assess the potential of HVI to predict surgical outcomes and assist with personalized treatment decisions.

12-month randomised trial of 360° and 180° Schlemm's canal incisions in suture trabeculotomy ab interno for open-angle glaucoma

Background/Aims

To perform a 12-month comparison between the different extents and locations of Schlemm’s canal incisions during suture trabeculotomy ab interno for open-angle glaucoma (OAG).

Methods

This is a prospective, single-centre, three-arm randomised trial. A total of 99 eyes of 99 patients were randomly assigned to one of three groups: the 360° incision group (n=34), the upper-180° incision group (n=34) and the lower-180° incision group (n=31). Intraocular pressure (IOP), number of medications and complications were evaluated until 12 months after surgery. Surgical success (with or without medication) was defined as IOP ≤21 mmHg and ≥20% IOP reduction (criterion A) or IOP ≤15 mmHg and ≥20% IOP reduction (criterion B).

Results

The mean IOP (±SD) in all eyes was reduced from 18.6 (5.9) mmHg with 3.1 (1.1) medications to 13.7 (3.4) mmHg (20.8% reduction; p<0.001) with 1.4 (1.3) medications (p<0.001) at postoperative 12-month. Each group produced comparable mean reductions in both IOP and the number of medications throughout 12 months of follow-up. Kaplan-Meier cumulative survival analyses showed no significance among these three groups for criterion A and criterion B. Postoperative hyphema with niveau formation occurred significantly more in the 360° group than in the lower-180° group (p=0.031).

Conclusions

The different extents and locations of Schlemm’s canal incisions during suture trabeculotomy ab interno for OAG, including the 360° incision, the upper-180° incision and the lower-180° incision, do not affect both the IOP reduction and the medications throughout 12 months of follow-up.

Trial registration number

UMIN000021169.

Aqueous outflow imaging techniques and what they tell us about intraocular pressure regulation

Recent advances in the medical and surgical management of open-angle glaucoma have increased the number of treatment options available. Several new intraocular pressure (IOP)-lowering treatments target the conventional aqueous outflow (AO) system. However, success rates are variable and outcomes in individual patients are often difficult to predict. Variable treatment responses remain unexplained and highlight deficiencies in our current understanding of AO regulation and IOP homeostasis. Imaging is often relied upon to confirm diagnoses and monitor treatment responses in other ocular and systemic pathologies. As yet no suitable AO imaging tool has been developed to fulfil this role in glaucoma. A variety of imaging techniques have been used to study the AO tracts of humans and animals in ex vivo and in vivo eyes. In this review, results from novel imaging techniques that assess aqueous drainage through the episcleral venous system are considered and we argue these provide new insights into AO regulation. We suggest that the ability to objectively measure AO responses to interventions would be a significant clinical advance, and we have demonstrated that this can be achieved with direct visualisation of aqueous drainage. We predict that the evolution of AO imaging technology will continue to reveal critical components of AO and IOP regulation, and that personalised IOP-lowering treatment in glaucoma care may well become a reality in the near future.

Minimally Invasive Glaucoma Surgery: What Do We Know? Where Should We Go?

With the arrival of a plethora of new and revolving minimally invasive glaucoma surgery techniques, glaucoma specialists currently are fortunate to have various surgical options that aim to recovery of the function of the aqueous outflow system in different ways. Meanwhile, the aqueous outflow system has become the hot point of researching. In ARVO 2019, a special interest group session was held on new perspectives on minimally invasive glaucoma surgery. Ten surgeons, clinical professors, and experimental scientists were invited to report their latest studies and discussed on five hot topics in this special interest group. This review summarizes the special interest group session and posts the issues of greatest concern, providing insight to the aqueous outflow system and areas that require further study.

Intraocular pressure elevation associated with blood in Schlemm's canal after strabismus surgery

Purpose

To report a case of increased intraocular pressure (IOP) associated with blood in Schlemm's canal following strabismus surgery.

Observations

A 43-year-old female presented with acquired comitant esotropia. The patient had undergone an uneventful bilateral medial rectus recession and right lateral rectus resection operation under general anesthesia. Routine post-operative follow-up at day 3 detected a marked chemosis at the temporal side of the conjunctiva, an elevated IOP of 30 mmHg, and the presence of blood in Schlemm's canal in the temporal angle of the right eye. Episcleral venous outflow impairment was hypothesized to be the cause of secondary ocular hypertension in this patient. IOP was controlled with anti-glaucoma drops. Conjunctival chemosis, IOP, and blood in Schlemm's canal gradually decreased, and all topical medications were ceased at 11 weeks after the surgery.

Conclusion and importance

An IOP elevation can be an early complication after strabismus surgery. The presence of blood in Schlemm's canal suggests that the cause is impairment of episcleral venous flow. Although the episode can be transient, this report underlines the importance of IOP examination during the early post-operative period.

Visual Assessment of Aqueous Humor Outflow

In the past decade, many new pharmacological and surgical treatments have become available to lower intraocular pressure (IOP) for glaucoma. The majority of these options have targeted improving aqueous humor outflow (AHO). At the same time, in addition to new treatments, research advances in AHO assessment have led to the development of new tools to structurally assess AHO pathways and to visualize where aqueous is flowing in the eye. These new imaging modalities have uncovered novel AHO observations that challenge traditional AHO concepts. New behaviors including segmental, pulsatile, and dynamic AHO may have relevance to the disease and the level of therapeutic response for IOP-lowering treatments. By better understanding the regulation of segmental, pulsatile, and dynamic AHO, it may be possible to find new and innovative treatments for glaucoma aiming at these new AHO behaviors.