Intraocular pressure reduction in a pigmentary glaucoma model by Goniotome Ab interno trabeculectomy

VEGF-A-induced changes in distal outflow tract structure and function

PURPOSE

To investigate changes in distal outflow tract vessels caused by VEGF-A and their impact on outflow.

METHODS

We compared VEGF-A perfused porcine anterior segments with and without trabecular meshwork (TM) to control eyes. In the first experiment (n=48), we analyzed live changes of the outflow tract with spectral-domain optical coherence tomography (SD-OCT) over 3 h and reconstructed them in 3D. In a second experiment (n=32), we measured the intraocular pressure (IOP) variation in response to VEGF-A over 48 h and computed the outflow facility.

RESULTS

VEGF-A increased the vessel volume of the distal outflow tract by 16.8±10.6% while control eyes remained unchanged (0.5±6.8%). Volume changes occurred within the first 100 min before plateauing at 140 min. VEGF-A enhanced the outflow facility in eyes without TM by 38.6±25.5% at 24 h as compared to controls (p<0.05).

CONCLUSION

VEGF-A dilated vessels of the distal outflow tract and increased the outflow facility even after TM removal, pointing to a regulatory mechanism independent of proximal structures.

Pigment dispersion syndrome and pigmentary glaucoma: overview and racial disparities

Pigment dispersion syndrome (PDS) and pigmentary glaucoma (PG) are two stages within the same ophthalmic disease spectrum, which are known to be affected by race. The prevalence of PDS is underestimated, largely due to its minor clinical symptoms. Although the prevalence of PG is low, the visual impairment associated with PG is extremely severe. The prevalence of PDS-PG is four or more times higher in Caucasians than in Blacks or Asians, and the "classic" PDS in Caucasians has long been used as a benchmark diagnostic criterion. Following extensive research focused on African Americans and Asians, the standard for diagnosing PDS-PG was refined. At the same time, the pathogenesis of PDS is not the same in different races. Hence, the effectiveness of preventive treatment and the need for treatment may not be equivalent in different races. The rate of conversion of PDS to PG is nearly 1/3 in Caucasians and higher in blacks and Asians, requiring more aggressive treatment and monitoring. We systematically searched a PubMed database from inception to March 2022 to provide an overview of research progress in various aspects of PDS-PG. Specifically, this paper considers the effects of race on disease prevalence, clinical manifestation, diagnostic criteria, disease mechanism, hereditary traits, treatment, and prevention to provide an accurate and comprehensive guide for the diagnosis and treatment of PDS-PG in various races.

Coarsened Exact Matching of Excisional to Plasma-ablative Ab Interno Trabeculectomy

Aim

To compare ab interno trabeculectomy by trabecular meshwork (TM) excision to plasma-mediated ablation in primary open-angle glaucoma (POAG) patients.

Methods

Retrospectively collected data of TrabEx+ (TEx) (n = 56) and Trabectome (T) (n = 99) patients were compared by coarsened exact matching to reduce confounding and matched based on baseline intraocular pressure (IOP) and age. The primary outcomes were IOP and the number of glaucoma medications. Complications and the need for additional glaucoma surgery were assessed. Patients were followed for up to 1 year.

Results

A total of 53 TEx could be matched to T. Baseline IOP was 16.5 ± 4.6 mm Hg in both; age was 73.7 ± 8.8 and 71.5 ± 9.9 years in TEx and T, respectively. TEx was taking more medications than T (p < 0.001). IOP was reduced to 14.8 ± 4.3 in TEx and to 13.4 ± 3.4 in T at 6 months, and to 14.9 ± 6.0 (p = 0.13) in TEx and to 14.1 ± 3.8 mm Hg (all p < 0.05) in T at 12 months. Medications were reduced at both 6 and 12 months (p < 0.05). No differences were seen between TEx and T at 6 and 12 months. In TEx, only one serious complication occurred, and two patients required further glaucoma surgery.

Conclusion

Although both groups had a baseline IOP considered low for ab interno trabeculectomy, IOP and medications were reduced further at 6 and 12 months. IOP reduction did not reach significance in TEx at 12 months. The intergroup comparison did not reveal any significant differences. Both had a low complication rate.

Clinical significance

This study investigated subtle differences between a plasma-ablative device, the T, and an excisional device, the TEx, by applying coarsened exact matching. IOP and medications were reduced in both groups at 6 and 12 months, although IOP reduction did not reach significance in TEx at 12 months. The intergroup comparison did not reveal any significant differences, with both devices having a low complication rate.

How to cite this article

Dakroub M, Verma-Fuehring R, Strzalkowska A, et al. Coarsened Exact Matching of Excisional to Plasma-ablative Ab Interno Trabeculectomy. J Curr Glaucoma Pract 2023;17(1):9-14.

Tissue-engineered anterior segment eye cultures demonstrate hallmarks of conventional organ culture

BACKGROUND

Glaucoma is a blinding disease largely caused by dysregulation of outflow through the trabecular meshwork (TM), resulting in elevated intraocular pressure (IOP). We hypothesized that transplanting TM cells into a decellularized, tissue-engineered anterior segment eye culture could restore the outflow structure and function.

METHODS

Porcine eyes were decellularized with freeze-thaw cycles and perfusion of surfactant. We seeded control scaffolds with CrFK cells transduced with lentiviral vectors to stably express eGFP and compared them to scaffolds seeded with primary TM cells as well as to normal, unaltered eyes. We tracked the repopulation behavior, performed IOP maintenance challenges, and analyzed the histology.

RESULTS

Transplanted cells localized to the TM and progressively infiltrated the extracellular matrix, reaching a distribution comparable to normal, unaltered eyes. After a perfusion rate challenge to mimic a glaucomatous pressure elevation, transplanted and normal eyes reestablished a normal intraocular pressure (transplanted = 16.5 ± 0.9 mmHg, normal = 16.9 ± 0.9). However, eyes reseeded with eGFP-expressing CrFK cells could not regulate IOP, remaining high and unstable (27.0 ± 6.2 mmHg) instead.

CONCLUSION

Tissue-engineered anterior segment scaffolds can serve as readily available, scalable ocular perfusion cultures. This could reduce dependency on scarce donor globes in outflow research and may allow engineering perfusion cultures with specific geno- and phenotypes.

Pigment dispersion syndrome: A brief overview

BACKGROUND

Pigment dispersion syndrome (PDS) is characterized by dispersion of pigment in the anterior chamber structures and can present with deposits on the central corneal endothelium or Krukenberg spindle, iris trans-illumination spoke-like defects, and increased pigmentation in the iridocorneal angle. It is more common in myopic patients with a predominance in young males in the third to fifth decade of life that affects about 1-2% of the population. PDS is a risk factor and can give lead to a rise in intraocular pressure (IOP) and secondary glaucoma. Pigmentary glaucoma (PG) can develop from PDS in the presence of elevated IOP coupled with glaucomatous optic neuropathy, retinal nerve fiber thinning, and/or visual field defects. PDS and PG have the same clinical features, representing different levels of severity on the same clinical spectrum.

RELEVANCE FOR PATIENTS

Early diagnosis, appropriate management, and follow-up of patients with PDS are important to prevent vision deterioration or blindness due to glaucomatous optic neuropathy.

Trabeculopuncture as a predictive test of distal outflow resistance in canal-based surgery

We investigated whether trabeculopuncture (TP) could detect distal outflow resistance to predict the outcome of canal-based glaucoma surgery such as ab interno trabeculectomy (AIT). These procedures have a high utilization in open angle glaucoma, but fail in eyes with an unidentified distal outflow resistance. We assigned 81 porcine eyes to two groups: trial (n = 42) and control (n = 39). At 24 h, four YAG-laser trabeculopunctures were placed nasally, followed by a 180° AIT at the same site at 48 h. The proportion of TP responders between both AIT groups was compared. Histology and outflow canalograms were determined. Both post-TP and post-AIT IOPs were lower than baseline IOP (p = 0.015 and p < 0.01, respectively). The success rates of TP and AIT were 69% and 85.7%, respectively. Sensitivity and specificity values of TP as predictive test for AIT success were 77.7% and 83.3%, respectively. The positive and negative predictive values were 96.6% and 38.5%, respectively. We conclude that a 10% reduction in IOP after TP can be used as a predictor for the success (> 20% IOP decrease) of 180° AIT in porcine eyes.

Early Results of Irrigating Goniectomy With TrabEx+: A Novel Device for the Treatment of Open-angle Glaucoma

PRCIS

Irrigating goniectomy with the TrabEx+ device can lower intraocular pressure (IOP) in patients with glaucoma, as a standalone procedure or combined with cataract surgery.

PURPOSE

The aim was to describe the efficacy and safety of irrigating goniectomy performed using the TrabEx+ device, either as a standalone procedure or combined with cataract surgery, in eyes with medically treated open-angle glaucoma.

METHODS

A retrospective case series of eyes treated by a single surgeon at a single UK teaching hospital. Data was collected at follow-up visits at 1 week, 3, 6, 12, 18, and 24 months postoperatively. Primary outcomes included IOP and glaucoma medication reduction after surgery. Proportion of eyes achieving >20% IOP reduction, IOP <21 mm Hg, and no reoperation were classified as surgical success.

RESULTS

Seventy-three consecutive eyes of 64 patients (mean age 68.4±13.7 y) were enrolled. 62% were treated as combined procedures with cataract surgery. Overall, mean IOP decreased from 31.3±7.3 to 20.9±10.4 mm Hg at the latest follow-up (34% reduction) (P<0.001) at the latest follow-up (16.1±10.3 mo) with mean preoperative medications decreased from 2.9±1.2 to 1.9±1.3 (P<0.001). 73% met the definition of success at latest follow-up. Postoperative complications were recorded including hyphaema (17%), uveitis (3%), hypotony (1%), and persistent vitreous hemorrhage (1%). Eighteen percent required reoperation because of treatment failure.

CONCLUSION

TrabEx+ appears to be effective in lowering IOP and medication with or without cataract surgery. However, long-term safety and efficacy will be better understood in a prospective study with longer follow-up.

Ripasudil in a Model of Pigmentary Glaucoma

Purpose

To investigate the effects of Ripasudil (K-115), a Rho-kinase inhibitor, in a porcine model of pigmentary glaucoma.

Methods

In vitro trabecular meshwork (TM) cells and ex vivo perfused eyes were subjected to pigment dispersion followed by K-115 treatment (PK115). PK115 was compared to controls (C) and pigment (P). Cytoskeletal alterations were assessed by F-actin labeling. TM cell phagocytosis of fluorescent targets was evaluated by flow cytometry. Cell migration was studied with a wound-healing assay. Intraocular pressure was continuously monitored and compared to after the establishment of the pigmentary glaucoma model and after treatment with K-115.

Results

The percentage of cells with stress fibers increased in response to pigment but declined sharply after treatment with K-115 (P: 32.8% ± 2.9%; PK115: 11.6% ± 3.3%, P < 0.001). Phagocytosis first declined but recovered after K-115 (P: 25.7% ± 2.1%, PK115: 33.4% ± 0.8%, P <0.01). Migration recuperated at 12 hours with K-115 treatment (P: 19.1 ± 4.6 cells/high-power field, PK115: 42.5 ± 1.6 cells/high-power field, P < 0.001). Ex vivo, eyes became hypertensive from pigment dispersion but were normotensive after treatment with K-115 (P: 20.3 ± 1.2 mm Hg, PK115: 8.9 ± 1.7 mm Hg; P < 0.005).

Conclusions

In vitro, K-115 reduced TM stress fibers, restored phagocytosis, and restored migration of TM cells. Ex vivo, K-115 normalized intraocular pressure.

Translational Relevance

This ex vivo pigmentary glaucoma model provides a readily available basis to investigate new drugs such as the rho-kinase inhibitor studied here.