Fighting for the middle ground in glaucoma

Treatment options

Space for cyclodestructive procedures in the middle ground of glaucoma management. Dermot McGrath reports

Although traditionally considered as a last-resort treatment option for refractory glaucoma in poorly sighted eyes, cyclodestructive procedures (CPC) are enjoying a renewed lease of life thanks to novel technologies such as endoscopic cyclophotocoagulation and micropulse transscleral cyclophotocoagulation, according to Prof Clement C Tham.

“I think there is definitely a role for these treatment options as part of what I call the ‘middle ground’ for glaucoma management in terms of invasiveness and IOP lowering capability,” Prof Tham said at the World Ophthalmology Congress 2020 Virtual.

In the treatment spectrum described by Prof Tham, IOPlowering drugs have the lowest risk, are least invasive and have low-to-moderate IOP-lowering properties, while at the other end of the scale trabeculectomy and glaucoma drainage device implantation carries a relatively higher risk, is more invasive but has a substantial IOP lowering capability.

Prof Tham, Chairman of Ophthalmology and Visual Sciences at The Chinese University of Hong Kong (CUHK), said that CPC belonged somewhere alongside classic minimally-invasive glaucoma surgery (MIGS) in the middle ground of this spectrum.

He said that moderately advanced glaucoma patients could potentially benefit from modern CPC techniques.

“For early to moderate glaucoma, it may be patients who cannot accept topical drugs or have poor drug compliance, those not adequately controlled by maximally-tolerable glaucoma drugs or laser trabeculoplasty, or patients who do not need substantial IOP reduction for sight preservation. For more advanced glaucoma, it may include patients with only one eye or high surgical risks who prefer intervention with lower surgical risk or patients who prefer a more rapid recovery and rehabilitation,” he said.

Today’s cyclodestructive procedures are usually performed by laser, explained Prof Tham.

“This technique of cyclophotocoagulation can be either transscleral (TSCPC) performed by diode or micropulse laser, or (ECP) endoscopic laser. The traditional method was cyclocryotherapy which was reserved for refractory glaucoma with poor visual potential because of significant complications associated with its use,” he said.

Prof Tham showed a video of micropulse cyclophotocoagulation which is regularly performed at his hospital.

“It works well. The laser probe glides over the area over the ciliary body in a continuous fashion to reduce aqueous production by coagulating the ciliary epithelium,” he said.

In terms of results, Dr Tham said that the scientific literature showed about an average 30% reduction in IOP using this technique.

“It is important to remember that even though the pressure reduction is not dramatic the procedure is safe and noninvasive, and it can be repeated in future if necessary,” he said.

Another option is endoscopic cyclophotocoagulation (ECP), which may be a good option in the presence of cataract, said Prof Tham.

“This technique requires access to the anterior chamber so usually a small corneal wound is required. However, when combined with phacoemulsification no additional incisions are required and it is a safe and effective way to address moderately controlled glaucoma and cataract in one procedure,” he said.

To assess the clinical benefit of ECP performed in conjunction with phacoemulsification, Prof Tham and co-workers recently carried out a randomised controlled trial. Of 48 eyes with primary

Prof. Clement C Tham

open-angle glaucoma, 21 underwent phacoemulsification alone and 27 received combined phacoemulsification and ECP.

“With phaco alone, the IOP reduction was 19.8% compared to 28.5% for combined phaco and ECP. The mean reduction in glaucoma drug use after surgery was 0.9 drugs (29%) for the phaco eyes and 1.6 drugs (48.5%) for the combined group, so there is a clear benefit in adding ECP to the mix when treating cataract at the same time,” he said.

As its name implies, the advantages of minimally invasive glaucoma surgery (MIGS) include the fact that it is less disruptive to the ocular anatomy than traditional glaucoma surgery, has a better safety profile and offers a faster procedure and faster recovery. Some MIGS devices may also be combined with phacoemulsification without the need for additional wounds, noted Prof Tham.

“There are some downsides to MIGS, however. It is still more invasive compared to transscleral forms of CPC and offers less IOP-lowering capability than traditional glaucoma surgeries. The cost of some of the devices may also be a prohibitive factor for some surgeons and patients,” he added.

Prof Tham predicted that sustained-release glaucoma drug implants such as iDose Travoprost (Glaukos) and Bimatoprost SR (Allergan) will soon join the middle ground of glaucoma treatments and help to address problems of adherence and correct administration.

Summing up, Dr Tham said that selecting the right treatment option will depend on a range of factors that need to be carefully weighed in each individual case.

“We need to ask how much IOP and/or drug reduction is needed. How much surgical risk can the patient accept, or the eye tolerate? The age of the patient is important, too, since more elderly patients may need less aggressive IOP lowering. Do they have visual significant cataract as this can change the strategy? What about the angle anatomy because some MIGS cannot be implanted in eyes with angle closure? And finally, the cost factor needs to be taken into account as well,” he concluded.