Intraocular Pressure Outcomes Following Transscleral Diode Cyclophotocoagulation Using Long and Short Duration Burns

Current trends and advancements in utilizing endoscopic cyclophotocoagulation for the Treatment of Glaucoma

Glaucoma ranks as the second most prevalent cause of global blindness. Presently, the reduction of intraocular pressure (IOP) stands as the sole efficacious method for addressing this condition. Endoscopic cyclophotocoagulation (ECP) is designed to mitigate aqueous humor production by inducing coagulation or closure of the ciliary body. Since its inception in 1990s, ECP has emerged as a pivotal modality in the therapeutic armamentarium for glaucoma. This review primarily elucidates the instrumentation employed in ECP for the treatment of glaucoma, the mechanisms underlying its efficacy in glaucoma management, and a comparative analysis of ECP in relation to other modalities for anti-glaucoma treatment. Furthermore, it examines the contemporary clinical utilization of ECP in glaucoma therapy, as well as the prevalent postoperative complications and their preventive measures. We anticipate that the role of ECP in the treatment of glaucoma will persistently evolve alongside advancements in the field. Particularly noteworthy is its expanding applicability in glaucoma therapy and its increasingly vital role in personalized comprehensive treatment approaches.

[Cyclophotocoagulation - current applications and practical aspects]

Despite the advent of a large variety of minimally invasive glaucoma surgery (MIGS) techniques cyclophotocoagulation (CPC) remains a popular treatment option to lower intraocular pressure (IOP) in glaucoma patients. Guidelines for glaucoma treatment point to the rather unphysiological mode of action and, thus, recommend CPC mainly for refractory glaucoma and/or eyes with limited visual potential. The primary target of CPC is the pigmented secretory ciliary body epithelium resulting in a decreased production of aqueous humor. In addition, an increase of aqueous outflow may contribute to the IOP lowering. CPC is generally considered a low risk intervention. However, macular edema, prolonged intraocular inflammation, vision loss, hypotony, pain or phthisis occur at considerable rates. Over the past decades new promising modes of cyclophotocoagulation have evolved aiming at reducing the risk of adverse effects and improving the efficiency. This article provides an overview of the different currently available cyclophotocoagulation modes: Besides the classic transscleral continuous-wave cyclophotocoagulation it covers endoscopic cyclophotocoagulation, micropulse transscleral laser treatment and transscleral controlled cyclophotocoagulation. Various practical aspects of the treatment in light of the current literature are being discussed.

Comparison of two protocols of diode laser transscleral cyclophotocoagulation in refractory glaucoma

INTRODUCTION

Diode laser transscleral cyclophotocoagulation (DLTSCPC) remains the most commonly used cyclodestructive procedure. Nonetheless, there is no common consensus on a standardized technique.

METHODS

In this prospective randomized pilot study we compare the "pop"-titrated and "slow-burn" DLTSCPC techniques for a follow-up period of 3 months. The major outcomes of this study were intraocular pressure (IOP) before and after the procedure and the incidence of adverse events. Furthermore, postoperative pain, postoperative intraocular inflammation and corrected distance visual acuity (CDVA) were evaluated.

RESULTS

Mean baseline IOP decreased from 37.9 ± 12.7 mmHg in the pop group and 41.2 ± 9.6 mmHg in the slow-burn group to 20.3 ± 13.9 mmHg and 21.3 ± 13.4 mmHg at the final follow-up visit, corresponding to a 45.8 ± 31.7% and 46.3 ± 32.6% reduction respectively. 64.3% and 57.1% of patients had IOP ≥6 and≤ 21 mmHg in the pop and slow-burn groups respectively. The occurrence of adverse events was similar in both groups, with 1 case of hyphema in the pop group and 2 cases in the slow-burn group, and 1 case of hypotony in each group. Mean CDVA remained unchanged until the end of follow-up from 2.05 ± 0.84 to 2.04 ± 0.8 logMAR in the pop group and from 1.93 ± 0.78 to 1.89 ± 0.7 logMAR in the slow-burn group. Nonetheless, 4 eyes in each group encountered CDVA loss. Postoperative pain and inflammation were also similar between groups.

DISCUSSION

At the 3rd postoperative month, safety and efficacy was similar in the two techniques. The relative ease of the slow-burn technique may make its application more appealing to ophthalmic surgeons beyond glaucoma specialists.

Case report: Cataract extraction/lensectomy, excisional goniotomy and transscleral cyclophotocoagulation: Affordable combination MIGS for plateau iris glaucoma

We report the successful treatment of angle closure glaucoma and plateau iris with combined early cataract surgery/lensectomy, goniotomy, and transscleral cyclophotocoagulation. The underlying mechanism of angle closure and plateau iris was addressed with cataract extraction and goniosynechiolysis. Goniotomy was used to enhance trabecular meshwork outflow and lower intraocular pressure, and the "slow burn" transscleral cyclophotocoagulation was safely performed to reduce the size of the ciliary processes. The unique combinations of these procedures restored the iridocorneal angle anatomy to normalize IOP and prevent vision loss from glaucoma in patients with plateau iris. This is a cost-effective option with longer term efficacy.

A new approach for CW-TSCPC to improve its safety and efficacy in glaucoma treatment

PURPOSE

The goal of our study was to compare the outcomes of transscleral diode cyclophotocoagulation using a new protocol with new settings. In fact, we targeted the ciliary body guided by transillumination, reduced the energy applied at each spot, and enlarged the treatment area posteriorly from the pars plicata to the pars plana.

PATIENTS AND METHODS

Data were collected retrospectively from two groups of glaucoma patients. The first group of patients underwent transscleral diode laser cyclophotocoagulation as usual, with one-row applications of a maximum of 1200mW of energy and a duration of 2000ms. The second group was treated in three rows, using the same settings as the first group. Transillumination was used continuously during all of our procedures, to focus accurately on the location of the ciliary body. Outcome measures included intraocular pressure (IOP) and visual acuity (VA) at baseline and at a minimum of 3 months postoperatively, as well as complications occurring up until last follow-up visit. Patients were considered successfully treated if their intraocular pressure was lowered by at least 25% compared to their baseline or if their intraocular pressure was less than 21mmHg after the procedure, with or without glaucoma medications.

RESULTS

Sixty eyes were treated with the one-row protocol, followed by 508 eyes treated with the three-row protocol. The mean follow-up was 19 (range 3-31) months. Success rates were 62% and 86% for the one-row group and three-row group, respectively. The IOP decrease was 40.5% (a mean reduction from 37.5±8.1mmHg to 22.3±10.2mmHg) in the one-row group and 57.6% in the three-row group (mean reduction from 36.05±10.4mmHg to 15.7±7.3mmHg), which was statistically significant in each group (P=0.0001). Additionally, a significant improvement in efficacy was found in the 3-row compared to the 1-row group (P=0.0001) No significant difference was found in VA before or after the procedure or between the 2 groups. No serious complications were reported.

CONCLUSIONS

Diode laser TSCPC is a practical, rapid and well-tolerated procedure. The treatment protocol used, with lower energy levels applied to the eye, guided systematically by transillumination and targeting a wider area, appears to be safer and more effective.

An update on continuous-wave cyclophotocoagulation (CW-CPC) and micropulse transscleral laser treatment (MP-TLT) for adult and paediatric refractory glaucoma

PURPOSE

Continuous-wave cyclophotocoagulation (CW-CPC) is often preferred to medical and surgical treatments for managing refractory glaucoma. This review summarizes diode CW-CPC indications, history, histopathology, methods, efficacy and safety. It also provides an overview of the latest data available on micropulse transscleral laser treatment (MP-TLT) that uses repetitive micropulses of diode laser energy in an off-and-on cyclical fashion.

METHODS

A literature review was conducted on transscleral CW-CPC (CW-TSCPC), endoscopic CPC (ECP) and MP-TLT. Relevant series of adult and paediatric patients were included for assessing the procedures.

RESULTS

Regarding CW-TCPC, highly variable success rates are reported in the literature, depending on the definition of success, type of underlying glaucoma, energy settings, follow-up duration and retreatment rates. CW-CPC often needs to be repeated, especially in paediatric patients. CW-CPC exposes to risks of inflammation and chronic ocular hypotony or phthisis with irreversible visual loss. CW-TSCPC has mainly been used in very severe forms of glaucoma, in painful eyes with limited visual potential or after filtering surgery failure. Published data on ECP are more limited but overall good success rates have been reported. Through the direct visualization of the targeted ciliary body in anatomically abnormal eyes, ECP is the preferred surgical procedure in paediatric refractory glaucoma. Complication rates are relatively low after ECP; however, large studies with long-term follow-up are needed. ECP may be used in difficult, refractory cases, but it is often used earlier when combined with cataract surgery. Despite limited data on the exact mechanism of action of MP-TLT and a lack of standardization of laser settings, the first data from heterogeneous case series shows that it has a similar efficacy and a better safety profile compared to CW-TSCPC in the medium term.

CONCLUSION

Although they may lead to sight-threatening complications, both CW-TSCPC and ECP seem effective. ECP appears to be superior to CW-TSCPC in paediatric refractory glaucoma. Unlike ECP combined with cataract surgery, evidence supporting a wider use of CW-TSCPC and MP-TLT in earlier stages of neuropathy is lacking. While it now appears that the safety profile of MP-TLT is superior to that of CW-CPC, robust prospective comparative studies including homogeneous and well-defined cohorts of patients are still needed to confirm an at least comparable efficacy in the long term.

Effectiveness and Safety of Long Duration versus Short Duration Diode Laser Transscleral Cyclophotocoagulation

Purpose

To compare the efficacy and safety of diode laser transscleral cyclophotocoagulation using either the long duration or short duration protocol.

Methods

Retrospective series of 23 consecutive patients with glaucoma who underwent continuous-wave diode laser transscleral cyclophotocoagulation from August 2016 to July 2018 at a tertiary hospital in Hong Kong. Laser pulse duration for the long and short duration protocols was defined as 3.0–4.0 and 1.5–2.0 s, respectively.

Results

There were 15 male and 8 female Chinese subjects (23 eyes), age 49–90 (71.3 ± 2.7), with 10 subjects that underwent long duration cyclophotocoagulation (power 1239.2 ± 78.3 mW, spots 13.9 ± 1.4) and 13 subjects that had short duration cyclophotocoagulation (mean power 1817.3 ± 85.7 mW, spots 14.4 ± 1.0). Six months after long and short duration cyclophotocoagulation, intraocular pressure decreased significantly from 29.9 ± 7.8 to 21.1 ± 6.5 (p < 0.01), and from 35.4 ± 2.7 to 24.1 ± 3.4 (p = 0.04), respectively, while glaucoma medications decreased significantly by 1.4 ± 0.5 (p = 0.02) in the long duration group only. Reduction of medications after short duration cyclophotocoagulation was less and did not reach statistical significance (0.9 ± 0.9, p = 0.15). There was no significant difference of visual deterioration and complication rates.

Conclusion

Both types of cyclophotocoagulation were equally effective in lowering intraocular pressure by 6 months, but the short duration protocol, using higher laser power, was able to achieve a greater and earlier reduction, at 3 months. However, the long duration protocol, using less laser power, appears better at reducing medication requirement by 6 months.

Randomized comparative trial of diode laser transscleral cyclophotocoagulation versus Ahmed glaucoma valve for neovascular glaucoma in Chinese - a pilot study

Purpose

This is a pilot study to compare the effectiveness and safety of diode laser transscleral cyclophotocoagulation (TSCP) with the Ahmed glaucoma valve (AGV) in the management of neovascular glaucoma (NVG).

Methods

Eyes with NVG and an IOP greater than 21 mmHg on maximal medications, without previous glaucoma surgery or cyclodestruction, were randomized for either TSCP or AGV implantation. These eyes were followed for at least 6 months and analyzed with respect to their visual outcome, IOP, number of glaucoma medications required, and related complications.

Results

Twenty eyes (eight TSCP and 12 AGV) of 19 subjects with a follow-up duration of greater than 6 months were recruited. Mean follow-up duration was 28.5±17.9 and 31.0±15.4 months for the TSCP and AGV groups, respectively (P=0.80). IOP was successfully controlled in 86% of the eyes for both interventions. By including preservation or improvement of visual acuity as additional criteria for overall success, success decreased to 63% for TSCP and 42% for AGV, although the difference was not statistically significant (P=0.65). Eyes that had TSCP had fewer complications and required less subsequent procedures, compared to those that underwent AGV implantation.

Conclusion

Both procedures were equally effective in controlling the IOP and reducing glaucoma medications in NVG. However, eyes with AGV implant tended to have higher rates of visual loss and complications, as well as requiring more postoperative procedures, than eyes that were treated with TSCP, although the difference was not statistically significant.

Transscleral Diode Laser Cyclophotocoagulation: A Comparison of Slow Coagulation and Standard Coagulation Techniques

PURPOSE

To compare the outcomes of standard pop-titrated transscleral cyclophotocoagulation (TSCPC) and slow-coagulation TSCPC in the treatment of glaucoma.

DESIGN

Retrospective case series.

SUBJECTS

This study included 78 eyes with glaucoma of any type or stage that underwent TSCPC as part of their treatment course.

METHODS

This study compared 52 eyes treated with slow coagulation TSCPC to 26 eyes treated with standard pop-titrated TSCPC. Patient demographics, treatment course, surgical techniques, settings and outcomes were assessed.

MAIN OUTCOME MEASURES

The main outcome measures were visual acuity (VA), intraocular pressure (IOP) and post-surgical complications.

RESULTS

The initial LogMAR VA was 1.94 (0.73) [mean (SD)] in the slow coagulation TSCPC group and 1.71 (0.90) in the standard TSCPC group (p=0.507). Initial IOP was 37 (13) mm Hg in the slow coagulation group and 39 (13) mm Hg in the standard group (p=0.297). The follow-up periods were 16.36 months and 24.68 months for the slow coagulation and standard groups (p=0.124). VA remained better than light-perception in 71.1% of slow coagulation treated patients and 65.0% of standard TSCPC treated patients (p=0.599). IOP remained below 20 mm Hg in 46% of slow coagulation treated patients and 44% of standard TSCPC treated patients (p=0.870). The mean number of complications was higher in the standard group [1.46 (1.24)] versus the slow coagulation group [0.62 (0.75)] (p=0.002). The incidence of the need for a second procedure (slow coagulation- 28.8%, standard- 23.1%, p=0.588) and maximum number of medications needed to control IOP postoperatively (p=0.771) were similar between the two groups.

CONCLUSIONS

In this case series, slow coagulation TSCPC and standard pop-titrated TSCPC resulted in similar VA and IOP outcomes in the treatment of glaucomatous eyes. The complication profiles of the techniques were also comparable, although standard TSCPC had a higher incidence of prolonged inflammation postoperatively. This study suggests that slow coagulation TSCPC may achieve equivalent control of IOP while reducing the incidence of prolonged post-operative inflammation-a feared complication of TSCPC-when compared to standard "pop-titrated" TSCPC.

Comparison of the safety and efficacy of triple sequential therapy and transscleral cyclophotocoagulation for neovascular glaucoma in the angle-closure stage

To compare the efficacy and safety of triple therapy combining intravitreal injection of anti-vascular endothelial growth factor, trabeculectomy, and pan-retinal photocoagulation via binocular indirect ophthalmoscopy, with that of transscleral cyclophotocoagulation (TCP) to treat neovascular glaucoma in the angle-closure stage. Eighteen triple therapy patients and 25 TCP patients between May 2014 and May 2016 were retrospectively analysed. Anterior chamber puncture and anti-VEGF intravitreal injection were performed on the first day of sequential therapy. Trabeculectomy was performed 3–5 d after injection; pan-retinal laser photocoagulation via binocular indirect ophthalmoscopy was initiated 5–7 d later. The IOP of the triple therapy group was lower than that of the TCP group (15.2 ± 2.2 vs. 20.0 ± 8.5 mmHg) and fewer anti-glaucoma drugs were used (0.5 ± 1.0 vs. 0.6 ± 1.0) after treatment. The success rates of the two groups were 89% and 60% respectively (P = 0.032). The visual function of 94% of triple therapy patients was preserved or improved compared to 64% of TCP patients with statistical significance (P = 0.028). No patient in the triple therapy group showed hypotony or eyeball atrophy. Compared to TCP, triple therapy shows higher success rate, fewer complications, and attributes to visual function preservation.