ECP provides primary secondary therapy option for glaucoma

By Dr Philip Bloom

IN SHORT: Employing ECP effectively reduces IOP when used early in the glaucoma treatment paradigm.
 

For 20 years I have effectively employed endoscopic cyclophotocoagulation (ECP) as a primary or secondary line of glaucoma treatment. ECP is a minimally invasive glaucoma surgical (MIGS) option capable of reducing IOP in the majority of patients and can potentially eliminate the need for drainage surgery, including trabeculectomy (trab) and glaucoma drainage devices (GDDs).

With few sight-threatening complications, this is an attractive option to patients facing higher-risk, invasive procedures, or it can serve as a supplemental tool that complements and enhances the effects of other procedures.

ECP combines light and endoscopy to produce a precise, visualised laser application. The endoscope allows for viewing the ciliary body from the anterior or posterior segment in real time. Ciliary processes are easily identified and treated with laser ablation, thus minimising trauma to adjacent healthy ciliary and other tissues.

Quick, sutureless and ocular surface-friendly, ECP shows destruction of the non-pigmented epithelium with little effect outside of the ciliary processes. Scanning electron microscopy displays shrinkage and effacement of the process without gross architectural destruction or collateral damage.

In contrast, eyes treated with traditional cyclophotocoagulation (CPC) demonstrate destruction of the pigmented and non-pigmented epithelium, pigment clumping, coagulative necrosis, and destruction of the deeper ciliary stroma.

The decision to proceed with ECP can be based on consideration of what some have referred to as ‘Bloom’s VUE Triad’ of factors: Visibility, oUtflow, and Efficacy. These considerations are examined in more detail as follows.

Visibility (not just probability)

ECP allows direct visualisation of the treatment endpoint with localised shrinkage of ciliary processes. This is particularly important in large eyes and eyes that have undergone previous surgery. In both of these groups of patients, the position of the ciliary body may be atypical, leading to poor results and increased complications with transscleral CPC.

The laser and endoscopic system (Endo Optiks/Beaver Visitec) provides the benefit of real-time visibility of the anatomy. There is no need to guess the location of the ciliary processes, and thus collateral damage to the surrounding tissues may be minimised.

Outflow (not just inflow)

Critical to the success of ECP is consideration of aqueous dynamics, both inflow and outflow. The decision should not be based solely on the plan to reduce inflow.

ECP is highly effective, but in my opinion, it is best used on patients with reasonable outflow, or surgeons risk failure. It is an obvious and helpful adjunct to cataract surgery in eyes with visually significant cataracts and mild to moderate glaucoma.

However, in eyes with moderate to advanced glaucoma, there is usually severely restricted outflow and typically also low inflow, leaving little ‘wiggle room’ to modulate treatment via reduction of inflow. So for patients with severe disease, I first perform a procedure to establish outflow (be it MIGS, trab, or GDD).

I then titrate the degree of additional ECP treatment (which can vary from 90° to 360°) based on the severity of the disease and risk assessment of factors including ‘target’ IOP, pharmacologic resistance, past procedures, and the very rare risk of hypotony.

Efficacy (not just safety)

ECP is largely successful in reducing ciliary body aqueous production. However, now that ophthalmologists are aiming for ever-lower target pressures after surgery, the extent of treatment efficacy may be the main issue. The effect of an ECP procedure is based on controlled tissue damage.

However, as it is a gentle, titratable and repeatable procedure, safety is not as overly concerning now as it had been in the past with previous more aggressive modalities of cyclo-ablation (for ECP, I prefer the term ‘cyclo-modulation’ rather than cyclo-destruction). The bigger question is whether the treatments lower pressure enough after surgery.

Think of it as an ‘untrabitional’ surgical procedure for patients with glaucoma. It is a mild process allowing for re-treatment if necessary, and patients are subject to reduced probability of sight-threatening risks associated with invasive procedures, such as trab or GDD surgery.

Cataract, glaucoma perfect pair for ECP

As an adjunct to small-incision cataract surgery, ECP is an ideal way to address moderately controlled glaucoma and cataracts in one procedure. Although cataract surgery alone may temporarily reduce IOP, targeting and ablating ciliary processes frequently enables patients to experience long-term IOP reduction comparable to the more invasive GDD procedures, but without the added risk of sight-threatening complications.

The process adds about 10 minutes to the overall surgery time and can prevent patients from needing additional glaucoma surgery. In cases where IOP is not lowered enough, I will supplement with a second ECP treatment. If IOP still remains high, I will often proceed to a trab or GDD.

Finally, if that does not produce results, I will try ECP again (perhaps via a posterior approach). In my experience, ECP helps outflow operations to work better when performed either before or after glaucoma outflow surgery.

For patients who are no longer responsive to or have an aversion to pharmacological treatments, ECP typically lowers IOP sufficiently to make it possible for them to discontinue one or two glaucoma medications and still maintain control.

Performing ECP sooner rather than later

My clinical experience has shown that utilising ECP earlier in the treatment paradigm is prudent practice. Patients experience more success when the procedure is performed in the early to moderate stages of glaucoma while outflow facility is only minimally reduced, and outflow resistance is rising but still functional.

Waiting to perform ECP in patients who have never received any other treatment, or until the disease is severe with very high outflow resistance, and often combined with already reduced inflow and little or no outflow facility, is unlikely to be a great success. Once the disease progresses to this stage, surgeons simply cannot reduce the inflow sufficiently to lower IOP in a patient with minimal or no outflow. Furthermore, this situation is brittle and may lead to hypotony if the already-reduced inflow is quickly reduced.

However, as in inflow procedure, ECP can play a role in augmenting previous outflow of other treatments in complicated glaucoma, particularly in patients who have already had a failed trabeculectomy or tube and are facing even more invasive surgery, such as a second tube operation.

Technique

My practice is usually to use ECP as a primary treatment when performed in conjunction with phacoemulsification and as a secondary treatment when treating glaucoma alone. There are four skills required to perform ECP:

·       watching a video monitor;

·       accessing ciliary processes once given the approach and lens status;

·       inflating the ciliary sulcus; and

·       controlling the long duration, invisible wavelength laser.

I initially perform ECP with phacoemulsification as an additive procedure. Phacoemulsification and IOL insertion are performed as normal. I remove the viscoelastic and then re-inject it to inflate the sulcus and perform ECP. It is simple to treat the facing 180° of the ciliary body with ECP through the normal phaco incision.

If further treatment is planned (as is usual), I enlarge my normal two side-port incisions to 1.5 to 2 mm, which is slightly larger than the 21-guage probe and permits horizontal movement in the wound and eliminates corneal torque. I treat the visible surface of the whole process as well as the area between the processes. Once the process shrinks upon treatment, it is not uncommon for new processes to be revealed behind the first row of them.

I utilise a phased treatment approach and typically start with ECP and then progress to ‘ECP plus’ (re-treatment with scleral indentation to expose untreated areas on previously treated processes and new posterior-sited processes) in refractory glaucoma cases.

With few exceptions, I treat the full 360°. Overtreatment is an inconsequential risk. There is a huge amount of ciliary epithelium and ECP is a gentle procedure. For a complicated eye, or the rare case when the eye is at increased risk for hypotony, I opt for 180° or 270° of treatment.

What to expect

The desired endpoint of treatment is whitening and shrinkage of the entire ciliary process. However, inflammation is an inevitable consequence of any intraocular procedure, including endoscopic treatment. When managed properly, inflammation is self-limiting and does not pose a problem.

To manage inflammation, I pre-treat patients with topical steroids and inject intracameral steroids at the end of the procedure. Inflammation should not be a deterrent to performing ECP. One should expect inflammation and treat it prophylactically to avoid surprises or complications.

Conclusion

ECP is a low-risk, minimally invasive surgical method offering IOP control and some liberation from the plethora of medications required for glaucoma patients. Using ECP earlier in the treatment paradigm to stem inflow when the outflow mechanisms are still functioning enables the greatest margin of success.

Used as a primary treatment for glaucoma in conjunction with cataract surgery, ophthalmologists can effectively reduce IOP without adding risk to the extraordinarily safe cataract surgery procedure. Consider the ‘untrabitional’ approach. Patients (and their eyes) will be happy.

Dr Philip Bloom, MD

E: philipbloom@zoo.co.uk

Dr Philip Bloom is a consultant ophthalmologist and honorary senior lecturer at Western Eye Hospital and Hillingdon Hospital, London.