Article

The role of micropulse therapy

This treatment lowers IOP, reduces medications and works with other interventions to manage glaucoma patients.

Worldwide, glaucoma is the most prevalent optic neuropathy, the second most common reason for vision loss and the most frequent cause of avoidable vision loss. Thankfully, technology has stepped up to meet demand, including the emergence of new therapies to treat all levels of disease. What we sometimes forget is that glaucoma is a chronic disease that needs to be managed with successive therapies over time. To have the greatest success, we need to think ahead. Current options should not hamper the success of future options.

Topical anti-glaucoma medications are the first-line treatment for the reduction of IOP. Advancements have been made in new chemicals, combination drops and even new delivery methods. However, long-term use of topical drugs increases the risk of failure of later incisional glaucoma surgery. Subclinical inflammation is present in patients receiving anti-glaucoma drops for long periods of time, with inflammatory cell infiltration and fibroblast activation in the conjunctiva and subconjunctival space. If the patient needs filtration surgery, the conjunctiva is primed for subconjunctival fibrosis that hampers the aqueous outflow and can lead to surgical failure.

I always hope to avoid a trabeculectomy, but, if it is needed, the patient should get a lot of bang for the buck. I do everything I can to ensure that a trabeculectomy will successfully control the patient’s IOP and that it will be the final surgery required. I don’t want the patient to have to go back on drops, and I certainly don’t want to plan for a failed trabeculectomy. Thus, my goal is to never have a patient on more than two topical medications. Avoiding medicines and/or preservatives that torture the conjunctiva bends the efficacy curve of trabeculectomy toward success. Avoiding prior conjunctival incisional surgery is another way. Trabeculoplasty, micropulsed laser ciliary body treatments, minimally invasive glaucoma surgery (often limited to cataract surgery) and goniotomy can help lower IOP without adding more drops.

I will discuss how I use them below.

MICROPULSE TRANSSCLERAL CYCLOPHOTOCOAGULATION

I frequently make use of MicroPulse transscleral cyclophotocoagulation (MP-TSCPC). The MicroPulse delivery mode applies the laser beam in an “on” and “off” cycle mode. This means that a continuous wave laser is broken into a sequence of multiple, repetitive, short pulses followed by longer rest periods that impede heat accumulation in the tissue and reduce aqueous production or improve aqueous outflow without damaging the targeted tissues.

MP-TSCPC with the MicroPulse P3 Glaucoma Device (Iridex) is a non-invasive, well-tolerated intervention, demonstrating a satisfactory efficacy and safety profile. The 810-nm, non-continuous laser beam is delivered over 360° along the limbus, excluding 3- and 9-o’clock sites, protecting the ciliary neurovascular structures. The process requires either local anesthesia or IV sedation and can be performed bilaterally in three minutes for each eye. Compared to traditional cyclodestructive procedures, MP-TSCPC with the MP3 probe produces less postoperative inflammation and pain, minimizes bleeding and reduces postoperative infection risks.

EFFICACY

In more than 300 patients who have received MP-TSCPC with the Cyclo G6 in my clinic, 95% are successful at six weeks and 82% are successful at two years in reducing a medication. This is consistent with other available data.7 My use tends to be in mild to moderate glaucoma and not end-stage disease, unless I need to calm a red, medicated eye prior to eventual trabeculectomy a few months to a year later. I think that is where the device shines.

MP-TSCPC also works well in tougher cases, as illustrated in the published literature. In a prospective case series of 40 eyes treated with MP-TSCPC, mean IOP was reduced from 39.3 mm Hg at baseline to 26.2 mm Hg at 18 months with no hypotony or loss of BCVA.8 Other recently reported data shows patients experience a 30% reduction in IOP and a 27% reduction in medication burden.9

ADVANTAGES

The low rate of complications across several trials convinced me to utilize this therapy in the early stages of the disease. I can effectively perform it on an eye at any stage of disease, in various types of glaucoma, regardless of the number of previous surgeries and can repeat it as often as needed. Also, I can perform the procedure in the operating room or the office, and it takes about three minutes for each eye.

Additionally, it is cost-effective in comparison to long-term medication and more invasive procedures, and Medicare covers it as a standalone or joint procedure.

I can also combine it with non-glaucoma surgeries. MP-TSCPC concurrent with ptosis surgery makes sense. Why lift the lid only to have it droop from prostaglandin analogs later? Following most MP-TSCPC procedures, I usually stop one medicine at one week and stop topical steroids at two weeks.

ADDITIONAL INTERVENTIONS

Thankfully, we have many surgical options for glaucoma with excellent safety profiles, and I employ many of them. Goniotomy is a minimally invasive surgical procedure that improves outflow and is not related to a bleb. By removing a part of trabecular tissue, it gives aqueous access to the collector channels and the distal outflow system. In a recent study using the Kahook Dual Blade (New World Medical), the mean IOP reduction postoperatively at nine months was 5.8 mm Hg (from 18.9% to 12.9%).10

The Omni Surgical System (Sight Sciences) is another option. It combines 360° canaloplasty with 360° trabeculotomy in one device and is suitable for the catheterization and transluminal viscodilation of Schlemm’s canal and the cutting of trabecular meshwork to decrease IOP in adult patients with open-angle glaucoma.

The first- and second-generation iStent/iStent inject (Glaukos) are trabecular micro-bypass products that directly connect the anterior chamber to Schlemm’s canal, creating a permanent passage for aqueous humor. They gained FDA-approval and CE mark in combination with cataract surgery, and the most recent data from the iStent inject shows an average IOP reduction of 6.9 mm Hg.11

MP-TSCPC is versatile and can be combined with iStent, Omni, Kahook Dual Blade, Hydrus microstent (Ivantis) or Xen Gel Stent (Allergan). I combine MP-TSCPC with other procedures when I need a low pressure (rather than simply a lower pressure). The addition of MP-TSCPC to those procedures can ensure a medication-spared, successful outcome. Patients like to get out of glasses, but they really love to get off their glaucoma drops.

CASE STUDY

A recent case shows how non-incisional, surgical therapies can improve a glaucoma patient’s quality of life. A 66-year-old woman presented on two different IOP-lowering medications. Having a strong family history, she suffered for 10 years from moderate glaucoma (Figure 1). She was allergic to brimonidine, could not take a beta blocker due to asthma and experienced hearing loss due to dorzolamide. Her IOP was 17 mm Hg with proven progression and with highest IOP at 21 mm Hg.

Figure 1. Visual field analysis shows glaucomatous damage in the right eye.

When considering treatment options, it was obvious that she needed lower pressure in her eye and cataract treatment. Our goals were to reduce both her spectacle dependence and anti-glaucoma medication. An additional eyedrop was not desired; she preferred a Crystalens (Bausch + Lomb). Additionally, given her already documented issues with medicine intolerances, we needed to minimize the risk of a subsequent surgery that could change the refractive status of her premium lens. Consequently, the patient was scheduled for MP-TSCPC prior to cataract surgery with Crystalens and iStent (Figure 2).

Figure 2. MicroPulse transscleral cyclophotocoagulation performed just before cataract surgery.

Postoperatively, her IOP was reduced to 10 to 12 mm Hg on no medicine, and she achieved 20/25 in distance and intermediate and 20/40 in near vision. Moreover, she now wears glasses only 5% of the time for near activities.

CONCLUSION

Today, with an abundance of treatment options, it is possible to successfully control glaucoma without diminishing the patient’s quality of life or prospects for future treatment. We owe it to our patients to make these tools part of our armamentarium and educate patients on the many options now available to treat glaucoma. OM

REFERENCES

  1. Butt NH, Ayub MH, Ali MH. Challenges in the management of glaucoma in developing countries. Taiwan J Ophthalmol. 2016 Jul-Sep;6:119-122.
  2. Broadway DC, Chang LP. Trabeculectomy, risk factors for failure and the preoperative state of the conjunctiva. J Glaucoma. 2001 Jun;10:237-249.
  3. Ramli N, Supramaniam G, Samsudin A, et al. Ocular surface disease in glaucoma: effect of polypharmacy and preservatives. Optom Vis Sci. 2015 Sep;92:e222-e226.
  4. Johnson M, Wang R, Padilla S, Wen K. Transscleral Laser Induces Aqueous Outflow Pathway Motion and Reorganization. Presented at the annual meeting of the American Glaucoma Society, March 2-5, 2017, Coronado, CA.
  5. Kuchar S, Moster MR, Reamer CB, Waisbourd M. Treatment outcomes of micropulse transscleral cyclophotocoagulation in advanced glaucoma. Lasers Med Sci. 2016 Feb;31:393-396.
  6. Gavris, MM, Olteanu I, Kantor E, Mateescu R, Belicioiu R. IRIDEX MicroPulse P3: innovative cyclophotocoagulation. Rom J Ophthalmol. 2017;61:107-111.
  7. Radcliffe N, Vold S, Kammer J, et al. MicroPulse trans-scleral cyclophotocoagulation (mTSCPC) for the treatment of glaucoma using the MicroPulse P3 device. Poster presented at the American Glaucoma Society annual Meeting. April 2015.
  8. Tan AM, Chockalingam M, Aquino MC, et al. Micropulse transscleral diode laser cyclophotocoagulation in the treatment of refractory glaucoma. Clinical and Experimental Ophthalmology. 2010;38:266-272.
  9. Radcliffe N, Vold S, Kammer J, et al. MicroPulse trans-scleral cyclophotocoagulation (mTSCPC) for the treatment of glaucoma using the MicroPulse P3 device. Poster presented at the American Glaucoma Society annual Meeting. April 2015.
  10. Abdullah S, Jasek, MC, Radcliffe NM, et al. A novel dual blade device for goniotomy: initial clinical experience. Invest Ophthalmol Vis Sci. 2016;57:6522.
  11. Samuelson TW. Prospective, randomized, multicenter clinical investigation of the Glaukos iStent inject. Presented at: American Society of Cataract and Refractive Surgery annual meeting; April 13-17, 2018; Washington, DC.

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