Novel approaches to model effects of subconjunctival blebs on flow pressure to improve clinical grading systems after glaucoma drainage surgery

Efficacy and safety of deep sclerectomy with uveoscleral implant plus collagen matrix implant overcoming the superficial scleral flap in glaucoma surgery

AIM

To assess the efficacy and safety of non-penetrating deep sclerectomy (NPDS) with uveoscleral implant plus subconjunctival and intrascleral collagen matrix overcoming the superficial scleral flap lips (modified deep sclerectomy technique, DS) and minimal use of mitomycin C in glaucoma surgery.

METHODS

A retrospective review of 47 consecutive glaucoma patients who underwent NPDS with DS between January 2017 and May 2018. Best-corrected visual acuity, intraocular pressure (IOP), post-operative need for glaucoma medications, visual field mean deviation (MD), re-interventions, needling revisions and laser goniopuncture were noted. Absolute success was defined as IOP≤18 mm Hg without topical medication. Relative success was defined as the same criteria but with the addition of any antihypertensive medication. IOP over 18 mm Hg on two consecutive follow-up visits was considered as a failure.

RESULTS

Fifty-two eyes of 47 patients were evaluated. Mean preoperative IOP was 25.37±6.47 mm Hg, and decreased to 15.04±4.73 at 12mo and 12.21±4.1 at 24mo (all P<0.0001). Requirement for topical medications dropped from a mean of 3.06±0.25 per patient to 0.51±0.99 and 1.11±1.23 respectively after 12 and 24mo (all P<0.0001). No medications were required in 45.5% of patients after 24mo. Relative and absolute success rate at 24mo were 85.5%±5% and 48.5%±7.4%, respectively.

CONCLUSION

DS is a safe and effective non-penetrating glaucoma surgery variation. It aims to retain the patency of all pathways created for aqueous humor drainage: the intrascleral bleb, the supraciliary space and the open communication between intrascleral and subconjunctival compartments.

Bleb morphology of glaucoma drainage devices on magnetic resonance imaging

PURPOSE

To evaluate bleb morphology features of different glaucoma drainage devices (GDD) using magnetic resonance imaging (MRI).

MATERIALS AND METHODS

Prospective cohort study of GDD and bleb morphology in consecutive glaucoma patients implanted with Ahmed Glaucoma Valve (AGV), Paul Glaucoma Implant (PGI), Baerveldt Glaucoma Implant (BGI) and Ahmed ClearPath (ACP) devices. Thirty-six eyes from 30 consecutive patients underwent standardized GDD implantation followed by MRI at least 1 month after surgery. Main outcomes included bleb volume and endplate position relative to the optic nerve. Secondary outcomes included intraocular pressure (IOP), medication and surgical complications during a 12-month follow-up.

RESULTS

Seven eyes were implanted with the AGV (19%), 5 with BGI (14%), 16 with PGI (44%) and 8 with ACP (22%). MRI scans were obtained 85 ± 66 days after surgery. Mean total bleb volume was 563 ± 390 mm3 . This bleb volume was inversely correlated with early post-operative IOP (day 7; rs  = -0.3326, p = 0.0475) but positively correlated with IOP at 12 months (rs  = 0.3592, p = 0.0341). No significant difference in total bleb volume was found between GDD types (p = 0.1223). A double-layered bleb was observed in 34 eyes (94%). The inferior bleb volume was significantly larger in PGI devices versus other GDD types (380 ± 205 vs. 193 ± 161 mm3 ; p = 0.0043). Distance from the endplate to the optic nerve was 9.5 ± 4.0 mm, similar across GDDs (p = 0.2519).

CONCLUSIONS

Double-layered blebs are a common finding with GDDs. Bleb volume showed different correlations with IOP at distinct timepoints and the PGI device formed larger blebs. A standardized GDD implantation technique ensures a safe distance from the GDD endplate to the optic nerve.

The control of conjunctival fibrosis as a paradigm for the prevention of ocular fibrosis-related blindness. "Fibrosis has many friends"

The processes involved in ocular fibrosis after disease or ocular tissue injury, including surgery play an important part in the development or failure of treatment of most blinding diseases. Ocular fibrosis is one of the biggest areas of unmet need in ophthalmology. Effective anti-scarring therapies could potentially revolutionise the management of many diseases like glaucoma worldwide. The response of a quiescent or activated conjunctiva to glaucoma surgery and aqueous flow with different stimulatory components and the response to different interventions and future therapeutics is a paradigm for scarring prevention in other parts of the eye and orbit. Evolution in our understanding of molecular and cellular mechanisms in ocular fibrosis is leading to the introduction of new and re-purposed therapeutic agents, targeting a wide range of key processes. This review provides current and futures perspectives on different approaches to conjunctival fibrosis following glaucoma surgery and highlights the challenges faced in implementing these therapies with maximal effect and minimal side effects.