Cyclophotocoagulation (CPC) for Glaucoma
What Is Cyclophotocoagulation (CPC)?
Cyclophotocoagulation (CPC) is a laser-based procedure used to lower eye pressure in patients with glaucoma by reducing the amount of fluid the eye produces. At Greenwich Ophthalmology Associates, our glaucoma specialists use several forms of CPC to help patients throughout the greater New York and Connecticut region who have not responded adequately to eye drops, oral medications, or prior surgical interventions. Whether you are facing advanced glaucoma or exploring alternatives after other approaches have fallen short, understanding how CPC works can help you make a more informed decision about your care.
Cyclophotocoagulation is a laser procedure that targets the ciliary body, the structure inside the eye responsible for producing aqueous humor, the clear fluid that maintains eye pressure.
During CPC, laser energy is applied to the ciliary body to decrease its ability to produce aqueous humor. By reducing the volume of fluid inside the eye, intraocular pressure (IOP) drops to a safer level. This helps protect the optic nerve from further glaucoma damage caused by elevated pressure.
The ciliary body sits behind the iris and continuously produces aqueous humor, which circulates through the front of the eye and drains through a structure called the trabecular meshwork. When this drainage system becomes impaired, fluid builds up and IOP rises. CPC addresses this problem at its source by limiting how much fluid is produced rather than relying solely on improving drainage.
CPC has traditionally been reserved for patients with advanced or refractory glaucoma, meaning their condition has not been adequately controlled with standard glaucoma treatments such as medicated eye drops or prior surgeries. However, newer and gentler forms of CPC are now being considered earlier in the treatment process for certain patients who may benefit from a less invasive laser option.
How CPC Lowers Eye Pressure
CPC reduces intraocular pressure by delivering targeted laser energy to the ciliary body, which decreases the production of aqueous humor inside the eye.
Unlike procedures that focus on improving fluid drainage, CPC works by reducing the amount of fluid being produced in the first place. The laser energy partially disrupts or modulates the ciliary epithelium, the cell layer within the ciliary body that generates aqueous humor. This results in a measurable decrease in IOP that can help slow or halt optic nerve damage.
Most CPC procedures use a diode laser, which emits light at a wavelength that is selectively absorbed by the pigmented tissue of the ciliary body. This allows the energy to reach its target through the sclera (the white outer wall of the eye) without requiring a surgical incision. The treatment can be delivered from outside the eye in a transscleral approach or from inside the eye using an endoscopic probe.
Traditional continuous-wave CPC works by destroying a portion of the ciliary body tissue. Newer micropulse technology takes a different approach, delivering short bursts of energy separated by rest periods that modulate the tissue rather than permanently destroying it. This distinction carries important implications for the safety profile and the range of patients who may benefit from the procedure.
Who Is a Candidate for Cyclophotocoagulation?
Candidacy for CPC depends on the type and severity of glaucoma, your overall eye health, and how well previous treatments have worked. Our glaucoma specialists evaluate each patient individually to determine whether CPC is an appropriate next step.
CPC is most commonly recommended for patients whose glaucoma has not responded to maximum medical therapy, meaning the highest tolerable combination of eye drops and oral medications, or to previous surgical procedures such as trabeculectomy or tube shunt implantation. These patients often have limited remaining treatment options, and CPC provides a way to lower pressure without another incisional surgery.
Some patients may not be good candidates for traditional filtering surgery due to other health conditions, prior eye surgeries, or anatomical factors that increase surgical risk. CPC can be an effective alternative for these individuals because it does not require creating a new drainage opening in the eye. It is typically performed in an outpatient setting with local anesthesia, which also makes it suitable for patients who may not tolerate general anesthesia well.
With the introduction of micropulse transscleral CPC, the candidate pool has expanded beyond advanced disease. Because micropulse CPC carries a lower risk of serious complications compared to traditional continuous-wave CPC, some patients with mild to moderate glaucoma may now be considered for this procedure. This is particularly relevant for patients who struggle with other laser treatments or who are unable to consistently use daily eye drops.
Types of CPC Procedures
There are several techniques used to perform cyclophotocoagulation, each with its own approach, safety profile, and ideal patient population.
This is the traditional form of CPC. A diode laser probe is placed against the outside of the eye and delivers a steady, continuous beam of energy through the sclera to the ciliary body. It is highly effective at lowering IOP, particularly in eyes with very high pressure. Because it permanently destroys tissue, it carries a higher risk of complications including prolonged inflammation, chronic low eye pressure (hypotony), and, in rare cases, shrinkage of the eye (phthisis bulbi). For this reason, continuous-wave CPC is generally reserved for eyes with advanced disease or limited visual potential.
Micropulse CPC uses the same diode laser but delivers energy in rapid, repeated short pulses rather than a continuous beam. Each pulse is followed by a brief rest period, which allows the targeted tissue to cool between bursts and reduces collateral damage to surrounding structures. Clinical studies have shown that micropulse CPC can reduce IOP by approximately 30 to 35 percent with a favorable safety profile and few serious complications. The procedure can often be repeated if the initial effect diminishes over time.
ECP uses a tiny endoscope inserted into the eye to deliver laser energy directly to the ciliary processes under direct visualization. Because the surgeon can see exactly where the laser is being applied, ECP allows for more precise treatment with less energy delivered to non-target tissue. It is frequently combined with cataract surgery and has demonstrated IOP reductions of roughly 34 percent in clinical studies. Complication rates with ECP tend to be lower than with traditional transscleral CPC, with serious events such as hypotony and phthisis being rare.
Frequently Asked Questions
For transscleral CPC, the eye is numbed with a local anesthetic injection, and a laser probe is placed against the surface of the eye. The treatment typically takes 10 to 20 minutes per eye. For ECP, the procedure is performed in the operating room, often at the same time as cataract surgery, and involves inserting a small probe through a tiny incision. Both approaches are outpatient procedures, and most patients go home the same day.
Most patients experience mild to moderate discomfort, redness, and blurred vision for the first several days. Anti-inflammatory eye drops are usually prescribed for several weeks to manage healing. Vision may fluctuate during the first month as the eye settles. Our glaucoma specialists schedule follow-up visits to monitor your pressure and adjust any medications as needed. You can find a more detailed timeline on our glaucoma surgery recovery page.
Traditional continuous-wave CPC carries a higher risk profile, including prolonged inflammation, hypotony, vision loss, and rare cases of phthisis bulbi. Micropulse CPC has demonstrated a notably better safety record, with most large studies reporting few to no serious complications. ECP carries a low risk of cystoid macular edema and temporary inflammation. Your ophthalmologist will discuss your individual risk factors before recommending a specific CPC technique.
Effectiveness depends on the technique used and the severity of glaucoma. Micropulse CPC has been shown to reduce IOP by approximately 30 to 35 percent in most published studies. ECP reports IOP reductions of around 34 percent, with success rates ranging from 76 to 94 percent at one to two years depending on how success is defined. Results vary by patient, and some may still need supplemental eye drops or additional procedures to maintain target pressure.
Yes. One of the advantages of CPC, particularly the micropulse technique, is that it can be safely repeated if eye pressure rises over time. Because micropulse technology modulates tissue rather than permanently destroying it, retreatment is a reasonable option without substantially increasing the risk of complications. Your ophthalmologist will determine appropriate timing for any retreatment based on your ongoing pressure readings and optic nerve health.
The decision between CPC and other surgical options depends on several factors, including your type and stage of glaucoma, overall eye health, and treatment history. For patients who have not responded to medications and less invasive procedures, CPC offers effective pressure reduction without traditional filtering surgery. If you are weighing your options, our team can help you understand when glaucoma surgery is needed and which approach is best suited to your situation.
Explore Your CPC Treatment Options
Cyclophotocoagulation continues to evolve as a valuable tool in glaucoma management, offering meaningful pressure reduction for patients who need it most. At Greenwich Ophthalmology Associates, our fellowship-trained glaucoma specialists in Stamford, CT work closely with you to determine whether CPC or another approach is the best path forward for preserving your vision. If your glaucoma has been difficult to control, or if you are looking for alternatives to daily eye drops, we are here to help you explore your options with confidence.
We encourage you to bring your questions and concerns to your next appointment so we can develop a care plan that addresses your goals and lifestyle.
Learn More About Related Topics
To further your understanding, explore our resources on Pigmentary Glaucoma and Pseudoexfoliation Glaucoma, Angle-Closure Glaucoma: Recognizing the Emergency, and Angle-Closure Glaucoma: Symptoms & Emergency Treatment.
You may also find these pages helpful: Brimonidine Eye Drops for Glaucoma, Caffeine and Glaucoma: How Much Is Too Much?, and Can Glaucoma Be Cured or Reversed?.
What our Patients say
4.8
Reviews
(3,408)