Take-home message: Charles L. Harris, MD, reviews safety and efficacy rates in a glaucoma case series after adding a proprietary laser system with probe to the surgical armamentarium.
By Charles L. Harris, MD, Special to Ophthalmology Times
Charles L. Harris, MDSavannah, GA—Cyclophotocoagulation (CPC) had once been considered as a last-resort treatment for patients with glaucoma. However, with new treatment paradigms, this is no longer the case.
A form of cycloablation, CPC is used to treat glaucoma through the destruction of ciliary body epithelium and stroma1,2 resulting in aqueous secretion reduction and lower IOP.
Newer treatments with contact transscleral (TSCPC) methods using an 810-nm, continuous-wave diode laser have proven safer and more efficacious in the treatment of various forms of glaucoma3-7 than traditional cyclocryotherapy, which carries more risks.8,9
Favorable safety profile
Safer still is a more recent paradigm (Cyclo G6 Laser System using MicroPulse Transscleral Cyclophotocoagulation [mTSCPC] with the MicroPulse P3 probe [Iridex]).
The technology breaks up the traditional continuous-wave laser into short bursts that allow the tissue to cool within the intervals between bursts. This minimizes collateral damage and has excellent safety and efficacy rates with most cases experiencing no incidence of visually significant hypotony or other complications, and superior rates of IOP reduction.10-13
Inflammation is always a risk which can be reduced with the use of a topical steroid. I prescribe the use of prednisolone acetate ophthalmic suspension (Pred Forte Allergan), however, this only needs to be administered for 4 or 5 days instead of weeks or longer as with past treatments.
Many of my patients present with uncontrolled pressures after numerous treatment paradigms have failed, including rigorous medication regimens and multiple selective laser trabeculoplasty (SLT) treatments.
With the MicroPulse P3, I have seen excellent pressure lowering and minimal recovery for patients other than a few hours of patching post-procedure. Visual acuity is unchanged and the treatment is repeatable if necessary. The primary goal is to control patients’ pressure and reduce or eliminate medications. To that end, I titrate the treatment based on the patients’ response.
Case One: A 78-year-old white female suffering with pseudoexfoliation glaucoma since 2005 presented as a referral for uncontrolled IOP in her right eye. She has no other concerning pathologies. She is pseudophakic, and upon presentation her visual acuity was 20/25 with a cup-to-disc ratio of 0.6. This patient was subject to an arduous medication regimen including the following:
Bimatoprost ophthalmic solution (Lumigan 0.03%, Allergan) once a day at bedtime;
Dorzolamide/timolol combination twice a day;
Brimonidine (2%) three times daily.
Recently begun oral acetazolamide (Diamox) at 250 mg four times a day.
The patient had undergone prior SLT procedures in 2008, 2012, and 2014. Despite the medication regimen and previous procedures, her pressure upon presentation was 31 mm Hg.
As the previous SLT procedures failed, I moved to the new modality, utilizing the laser system with the probe. The patient was given 4 ccs of 2% lidocaine retrobulbar with topical proparacaine prior to the procedure. Treatment parameters were 80 seconds superiorly and 80 seconds inferiorly at a power level of 2,000 mW.
The patient required a second treatment and the parameters changed to 160 seconds inferiorly and 100 seconds superiorly with the power level remaining at 2,000 mW.
Post-procedure, the patient was removed from oral acetazolamide, and began prednisolone acetate three times a day for 5 days. The patient’s pressure was significantly reduced after each procedure (Table 1).
While it was necessary to repeat the treatment, her pressure is currently stable at 2 months post-initial procedure.
At 2 months post-procedure, this patient is holding stable at a pressure of 10 mm Hg and has ceased brimonidine treatment.
Case Two: A 68-year-old white male presented with primary open-angle glaucoma (POAG) in the left eye. His medication regimen included:
Brinzolamide (Azopt, Alcon Laboratories) three times a day;
Brimonidine tartrate/timolol maleate ophthalmic solution 0.2%/0.5%; Combigan, Allergan) twice a day;
Bimatoprost ophthalmic solution 0.01% (Lumigan 0.01%, Allergan) at bedtime;
Oral acetazolamide (Diamox) 250 mg four times a day.
He is pseudophakic with a posterior chamber IOL and had undergone prior SLT procedures in 2006, 2008, and 2014. Upon presentation, his cup-to-disc ratio was 0.8 to 0.9 and he had a visual acuity of 20/25. His pressure was 31 mm Hg. This briefly decreased to 23 mm Hg with oral acetazolamide, however, that was a temporizing measure.
As with the previous case, this patient was treated with the laser system and probe, with 4 ccs of 2% lidocaine retrobulbar and topical proparacaine pre-procedure. He was treated for 100 seconds superiorly and 160 seconds inferiorly at a power level of 2,000 mW. He was also placed on Pred Forte for 5 days. At week one post-procedure, his pressure had decreased to 17 mm Hg and has remained stable through 1-month follow-up (Table 2).
Case Three: This case has been especially challenging. A 77-year-old pseudophakic female presented with advanced pseudoexfoliation open-angle glaucoma. She had a cup-to-disc ratio of 0.9 and visual acuity of 20/30. Her pressure continuously varied between 22 and 23 mm Hg on the following medications:
Bimatoprost ophthalmic solution 0.01%
0.5% timolol maleate ophthalmic solution (Istalol, Bausch + Lomb) once daily;
0.004% travoprost ophthalmic solution (Travatan Z, Alcon) once daily;
She has continued these medications though her regimen does not include brimonidine, to which she is allergic.
Additional pathologies include corneal map dot fingerprint dystrophy—the abnormal development of the epithelium’s basement membrane—and progression of the optic nerve. As with the other patient cases, this patient has undergone SLT on several occasions. One of these procedures resulted in a corneal abrasion, obtained while checking for pressure spikes.
This patient was treated with the laser system and probe at 80 seconds both superiorly and inferiorly. Due to her history, this patient has been followed very closely.
The procedure was repeated in order to obtain a more permanent drop in pressure. While some patients may opt for a trabeculectomy or shunt at this point, this patient preferred to continue the MicroPulse procedures as they have a much better safety profile.
At week 6, she experienced a rise in pressure and a MicroPulse laser trabeculoplasty (MLT) procedure was performed. At 1-month post-procedure, her pressure again spiked and a second MP3 procedure was scheduled.
However, when the patient presented for the treatment, her pressure had stabilized and the treatment was no longer required. At more than 3 months post-initial procedure, her pressure is stable at 14 mm Hg (Table 3). She remains on her medications and her corneal surface disease is stable from the anterior basement dystrophy (map dot fingerprint) disease.
Though this modality is new to my practice, the excellent results thus far confirm confidence in its safety and efficacy and make this treatment a welcome tool in the armamentarium.
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10 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.
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12Aquino MC, Barton K, Tan AM, et al. Micropulse versus continuous wave transscleral diode cyclophotocoagulation in refractory glaucoma: A randomized exploratory study. Clin Experiment Ophthalmol. 2014;10:1-7.
13Kuchar SD, Moster M, Waisbourd M. Treatment outcomes of microPulse transscleral cyclophotocoagulation in advanced glaucoma. Poster presented at: Congress of the American Glaucoma Society. 2015 Feb 27; San Diego.
Charles L. Harris, MD, is a board-certified ophthalmologist, Southern Retina, Savannah, GA, and clinical instructor, Department of Ophthalmology, Medical College of Georgia.