Efficacy and safety of the pars plana clip in the Ahmed valve device inserted via the pars plana in patients with refractory glaucoma

Long-term outcomes of pars plana Ahmed valve implant and vitrectomy in eyes with refractory glaucoma

Background

Pars plana vitrectomy with implantation of an Ahmed glaucoma valve in the vitreous cavity has been reported with a success rate in the management of refractory and neovascular glaucoma. This study aimed to present the outcomes of pars plana Ahmed glaucoma valve (PPAV) surgical implantation in cases with refractory glaucoma.

Methods

In this single-center, retrospective, comparative study, 87 consecutive patients diagnosed with refractory glaucoma who underwent PPAV surgical implantation between October 2015 and October 2019 were evaluated. A successful postoperative outcome was defined as intraocular pressure (IOP) ≤ 21 mmHg upon examination and a reduction in the number of anti-glaucoma agents used at the latest follow-up.

Results

Finally, 81 eyes of 78 patients with refractory glaucoma were included; 54 (66.66%) of the eyes had neovascular glaucoma. The mean follow-up was 20.65 ± 12.17 months (range: 2-52 months). The mean preoperative IOP was 40.01 ± 1.19 mmHg and reduced significantly to 16.73 ± 0.82 mmHg at the latest follow-up (P < 0.001); a successful IOP outcome was achieved in 88.89% of eyes. The mean number of anti-glaucoma agents decreased significantly from 2.86 ± 0.09 preoperatively to 1.46 ± 0.11 at the latest follow-up (P < 0.001); while 61 (75.31%) of eyes had a reduction in the number of IOP lowering eye drops, and 14 (17.28%) had no need for IOP lowering eye drops.

Conclusions

PPAV surgery is a successful procedure for IOP reduction in patients with refractory glaucoma. Our study demonstrated either reduction or elimination of IOP lowering eye drops postoperatively. Large scale studies with a comparison group, a longer follow-up, and having various subtypes of glaucoma are required as future research to confirm these outcomes.

Pars Plana-Modified versus Conventional Ahmed Glaucoma Valve in Patients Undergoing Penetrating Keratoplasty: A Prospective Comparative Randomized Study

PURPOSE

To compare the outcome of pars-plana-modified Ahmed glaucoma valve (AGV) versus limbal-based conventional AGV into the anterior chamber, in patients undergoing penetrating keratoplasty (PK) for glaucoma with coexisting corneal diseases.

METHOD

In this prospective randomized clinical trial, 58 eyes of 58 patients with glaucoma and coexisting corneal disease were divided into two groups. Group 1 (29 eyes of 29 patients) included patients undergoing limbal-based conventional AGV into the anterior chamber (AC) along-with PK and group 2 (29 eyes of 29 patients) included those undergoing pars-plana-modified AGV along-with PK. Outcome measures included corneal graft clarity, intraocular pressure (IOP), number of antiglaucoma medications, and postoperative complications. Patients were followed up for a minimum period of 2 years.

RESULTS

Out of 58 eyes (58 patients), 50 eyes (50 patients: 25 eyes of 25 patients each in group 1 and group 2) completed the study and were analyzed. Complete success rate for AGV (group 1: 76%; group 2: 72%; p = 0.842) and corneal graft clarity (group 1: 68%; group 2: 76%; p = 0.081) were comparable between the two groups at 2 years. Graft failure was more in conventional AGV (32%) as compared to pars plana-modified AGV (24%) but not statistically significant (p = 0.078) at 2 years.

CONCLUSION

Though both procedures were comparable in various outcome measures, pars-plana-modified AGV is a viable option for patients undergoing PK, as it provides a relatively better corneal graft survival rate and lesser complications that were associated with conventional AGV.

One-Year Feasibility Study of Replenish MicroPump for Intravitreal Drug Delivery: A Pilot Study

PURPOSE

To determine the feasibility of the surgical procedure and to collect some safety data regarding the bioelectronics of a novel micro drug pump for intravitreal drug delivery in a Beagle dog model for up to 1 year.

METHODS

Thirteen Beagle dogs were assigned to two groups. The experimental group (n = 11) underwent pars plana implantation of MicroPump; the body of which was sutured episclerally, while its catheter was secured at a pars plana sclerotomy. The control group (n = 2) underwent sham surgeries in the form of a temporary suturing of the MicroPump, including placement of the pars plana tube. Baseline and follow-up exams included ophthalmic examination and imaging. The experimental animals were euthanized and explanted at predetermined time points after surgery (1, 3, and 12 months), while the control animals were euthanized at 3 months. All operated eyes were submitted for histopathology.

RESULTS

Eyes were scored according to a modified McDonald-Shadduck system and ophthalmic imaging. Neither the implanted eyes nor the control eyes showed clinically significant pathological changes beyond the expected surgical changes. The operated eyes showed neither significant inflammatory reaction nor tissue ingrowth through the sclerotomy site compared with the fellow eyes.

CONCLUSION

This study shows that the Replenish Posterior MicroPump could be successfully implanted with good safety profile in this animal model.

TRANSLATIONAL RELEVANCE

The results of this study in a Beagle dog model are supportive of the biocompatibility of Replenish MicroPump and pave the way to the use of these devices for ocular automated drug delivery after further testing in larger animal models.

Pars plana Ahmed valve and vitrectomy in patients with glaucoma associated with posterior segment disease

PURPOSE

To assess the safety and efficacy of a modified technique for pars plana placement of the Ahmed valve in combination with pars plana vitrectomy in the treatment of glaucoma associated with posterior segment disease.

METHODS

Thirty-nine eyes with glaucoma associated with posterior segment disease underwent pars plana vitrectomy combined with Ahmed valve placement. All valves were placed in the pars plana using a modified technique, without the pars plana clip, and using a scleral patch graft.

RESULTS

The 24 eyes diagnosed with neovascular glaucoma had an improvement in intraocular pressure from 37.6 mmHg to 13.8 mmHg and best-corrected visual acuity from 2.13 logarithm of minimum angle of resolution to 1.40 logarithm of minimum angle of resolution. Fifteen eyes diagnosed with steroid-induced glaucoma had an improvement in intraocular pressure from 27.9 mmHg to 14.1 mmHg and best-corrected visual acuity from 1.38 logarithm of minimum angle of resolution to 1.13 logarithm of minimum angle of resolution. Complications included four cases of cystic bleb formation and one case of choroidal detachment and explantation for hypotony.

CONCLUSION

Ahmed valve placement through the pars plana during vitrectomy is an effective option for managing complex cases of glaucoma without the use of the pars plana clip.

[Ahmed glaucoma valve via pars plana access. Long-term results of implantation for therapy refractive glaucoma]

BACKGROUND

Aim of this study is the presentation of long-term results regarding the effectiveness and safety of the implantation of Ahmed glaucoma valve (AGV) devices using a pars plana approach after vitrectomy in the treatment of therapy refractive glaucoma.

METHODS

The implantation of AGV devices using a pars plana approach after vitrectomy was performed in 27 eyes of 22 patients with neovascular glaucoma (n = 7 patients), uveitis (n = 6), complex juvenile secondary glaucoma (n = 4), primary open angle glaucoma (n = 3), pseudoexfoliation glaucoma (n = 1) and nanophthalmus (n = 1). Intraocular pressure, visual acuity and subsequent complications were documented. The mean follow-up period was 23.6 months.

RESULTS

Intraocular pressure was significantly reduced from 30.2 mmHg preoperatively to 13 mmHg after a follow-up of 36 months. The mean visual acuity did not change significantly, five eyes required a subsequent explantation of which three were due to AGV-related complications.

CONCLUSIONS

The implantation of AGV devices using a pars plana approach permits an effective and permanent reduction of intraocular pressure (IOP) even in severe therapy refractive secondary glaucoma; however, the risk of serious sight-threatening complications has to be taken into account.