Micropulse transscleral cyclophotocoagulation (MP-TSCPC)
Micropulse transscleral cyclophotocoagulation (MP-TSCPC) is a non-incisional glaucoma surgery used to lower intraocular pressure. You may also see it called MicroPulse P3® cyclophotocoagulation after the Iridex device used to perform the procedure.
MP-TSCPC has, at least until recently, been used mostly in cases of refractory (hard-to-manage) glaucoma. Whereas older cyclophotocoagulation techniques (such as continuous wave) were typically used only in refractory cases with poor visual potential, MP-TSCPC can also be used in many more patients. It may be used in patients with mild, moderate, or severe glaucoma. MP-TSCPC is now even being considered as an early therapy for glaucoma, and some ophthalmologists consider it suitable even for glaucoma suspects.
Dr. David Richardson feels that MP-TSCPC is the most promising of the currently approved laser therapies for glaucoma. He says,
When it works, it can work really well. I just had a patient drop from an IOP near 40 to just under 10mmHg. However, it is somewhat unpredictable, is quite surgeon (technique) dependent, and is not without potential risks (the most common being lasting pupil dilation).
Dr. David Richardson continues:
In the case of the patient mentioned above, I was surprised because I had titrated down the energy used in order to avoid permanent pupil dilation for which the patient was at a higher risk. As the IOP-lowering response to MP-TSCPC tends to be somewhat dependent on the energy used he really should not have responded as well as he did. This is an example of why this procedure can be somewhat unpredictable.
That being said, it’s rapidly becoming my “go to” recommendation for many who have failed other treatments and wish to avoid or at least delay trabeculectomy or glaucoma drainage devices. It can also be used after failed trabs or tubes.
MP-TSCPC is an outpatient procedure. The patient receives a peribulbar block (anesthesia around the eye) or IV-anesthesia prior to the laser. The laser procedure takes approximately 10-15 minutes and does require good surgical technique, as well as postoperative drops to decrease inflammation in the eye. Most patients have minimal postoperative pain.
Since there is no incision, there are usually no postoperative restrictions associated with MP-TSCPC, but you will have to wear a patch on the eye for the first 24 hours and your doctor will probably want to see you the day following the procedure in the office to check your IOP
MP-TSCPC may be repeated if the desired eye pressure is not achieved. The procedure can also be customized for each patient.
This video by Dr. Murray Johnstone shows how MP-TSCPC works. The ciliary body muscle bundle shrinks. Ciliary muscle shortening causes the scleral spur to move backward and inward placing tension on the trabecular meshwork tissues. The effect is similar to that of pilocarpine, a drug that improves aqueous outflow and reduces intraocular pressure. It stretches open the eye’s drainage system and does not appear to reduce aqueous humor production. The ciliary epithelium tissue (where aqueous humor is produced) is not destroyed in MP-TSCPC, while other forms of cyclophotocoagulation are considered destructive (and classified as cyclodestructive).
MP-TSCPC may be contrasted with these older cyclodestructive procedures, which date back to the 1930s. Cyclodestructive procedures damage the secretory epithelium of the ciliary process, which leads to reduced aqueous humor secretion and lower IOP.