Cyclophotocoagulation (CPC) for Glaucoma
What Is Cyclophotocoagulation and How Does It Work
Cyclophotocoagulation is a laser treatment that reduces eye pressure by lowering the amount of fluid your eye produces. Understanding how and when it is used helps you take an active role in your treatment decisions.
Glaucoma causes damage to the optic nerve, the nerve that carries visual information from your eye to your brain, most often because of elevated pressure inside the eye. CPC lowers that pressure by targeting the ciliary body, a ring of tissue inside your eye that continuously produces fluid. When we treat portions of the ciliary body with laser energy, fluid production decreases, and pressure drops as a result.
CPC does not reverse vision loss that has already occurred, but it can help protect the vision you still have by keeping pressure within a safer range.
We typically consider CPC when eye drops, oral medications, and other glaucoma procedures have not lowered your pressure enough, or when other surgical options carry too much risk for your situation. For some patients, CPC offers a meaningful middle step between ongoing medication and more complex surgery.
- Pressure remains too high despite maximum medical therapy
- Previous glaucoma surgeries have not worked or are not suitable
- You cannot tolerate or afford long-term glaucoma medications
- Advanced glaucoma requires additional pressure reduction when other options are limited
Several techniques exist, and the right one depends on your eye health, the severity of your glaucoma, and whether you are having other procedures at the same time.
- Transscleral CPC delivers laser energy through the white outer wall of your eye without cutting into it, making it the least invasive approach
- Micropulse CPC uses short bursts of energy rather than a continuous beam, which may reduce tissue damage and is often considered earlier in treatment for eyes that still have useful vision
- Endocyclophotocoagulation, or ECP, treats the ciliary body from inside the eye using a tiny camera and laser probe, usually performed during cataract surgery in an operating room
Traditional continuous-wave CPC is typically reserved for more advanced glaucoma or for patients who are not good candidates for other surgeries. It delivers more energy to the ciliary body and has a higher risk of side effects. Micropulse CPC is a gentler approach that many eye doctors now consider earlier in treatment because it may cause less inflammation and fewer complications, though risks still exist with any technique.
Are You a Good Candidate for CPC
Not every patient with glaucoma needs or benefits from CPC. During your consultation, we will review your full picture to help determine whether this treatment is the right fit for you.
Good candidates include patients with moderate to severe glaucoma who need better pressure control and for whom medications or other surgeries have not provided enough relief. Patients who have had prior eye surgeries that have complicated the anatomy of the eye may also be strong candidates for CPC. Your overall eye health, the amount of vision you still have, and your ability to follow aftercare instructions all factor into the decision.
Certain conditions require careful evaluation before we proceed with CPC. Active inflammation inside the eye, for example, may need to be treated first. Eyes with very thin outer walls or a history of prior surgery may require a specific technique to minimize risk.
- Active inflammation may need to be resolved before treatment can begin
- Eyes at higher risk of very low pressure after treatment require close planning
- Safety considerations differ between continuous-wave, micropulse, and ECP techniques
- Glaucoma subtypes such as neovascular or uveitic glaucoma carry different risk profiles
CPC can meaningfully lower eye pressure in many patients, but results vary depending on the type and severity of your glaucoma, the technique used, and how well you follow aftercare instructions. Some patients achieve excellent long-term control, while others experience pressure rising again over time and may need a repeat procedure or additional surgery. We will discuss your individual situation and set realistic goals before you decide on treatment.
Preparing for Your CPC Procedure
A little preparation before your appointment helps the procedure go smoothly and supports a faster recovery. We will walk you through each step in advance so there are no surprises.
Before scheduling your CPC, we perform a thorough eye exam to measure your pressure, examine your optic nerve, and document your current level of vision. We may also take photographs of your optic nerve, perform optical coherence tomography (OCT) imaging to map nerve fiber thickness, and complete visual field testing to measure how much of your peripheral vision remains. These tests serve as your baseline and help us track your progress after treatment.
Most glaucoma eye drops should be continued as usual up to and including the day of your procedure unless we specifically advise otherwise. If you take blood thinners such as aspirin or warfarin, what to do depends on the type of CPC, your anesthesia plan, and your overall health history. Never stop blood thinners on your own. Changes to those medications require agreement from both your prescribing doctor and our surgical team.
- Continue glaucoma drops as prescribed unless told otherwise
- Report all blood thinners and follow guidance from our care team before stopping them
- Mention diabetes medications, since fasting before sedation may affect your dosing
- Bring a complete list of all medications, vitamins, and supplements on procedure day
You will need a driver to take you home after your appointment, because your vision may be blurry and you may receive sedation. Plan to take the rest of the day off to rest at home. Wear comfortable, loose clothing and avoid applying makeup or lotions to your face that morning.
Eat a light meal unless our office advises fasting, bring your insurance information and medication list, and try to arrive a few minutes early. Arriving relaxed and on time makes the entire experience easier for you.
We perform most CPC procedures using numbing eye drops combined with a local anesthetic injection near the eye to block deeper pain. Many patients also receive mild intravenous sedation to help them feel calm and comfortable during the procedure. The combination of these approaches means most patients tolerate CPC well without needing to be fully asleep. General anesthesia is rarely required but may be an option in special circumstances.
What to Expect During Your CPC Procedure
Knowing what will happen step by step can ease any anxiety you have before your appointment. The procedure is precise and relatively brief, and our team will guide you through every moment.
Once your eye is thoroughly numbed and you are comfortable, we gently place a small laser probe against the white outer surface of your eye. We deliver carefully timed laser pulses to the ciliary body tissue underneath, moving the probe to several positions around your eye to treat the tissue evenly. You do not need to hold still in any special way, and we will talk you through each step as we go.
After completing all the planned treatment areas, we remove the probe and may apply a medicated drop or ointment to the eye. The laser phase of the procedure usually takes between 10 and 20 minutes per eye.
Because of the anesthesia, most patients feel very little during CPC. You may sense a mild pressure sensation when the probe is placed on your eye, and you might notice brief warmth or a faint tingling when the laser fires. Tell us immediately if you experience sharp pain so we can adjust your comfort before continuing.
- Gentle pressure when the probe rests on the surface of your eye
- Awareness of clicking sounds as the laser fires
- Possible brief warmth or tingling in the treated area
- Most patients do not feel sharp pain due to effective numbing, though some discomfort can occur
You will rest briefly after the procedure while we monitor your initial response. We will check your eye pressure before you leave and may adjust your drop regimen based on what we measure. Your eye may look red and feel sore once the numbing wears off, and some blurriness is normal right away. We will review your home care instructions, provide any new prescriptions, schedule your first follow-up visit, and make sure you know which symptoms need urgent attention before you head home.
Recovery and Aftercare After CPC
A careful recovery protects your results and helps your eye heal well. Following our instructions closely in the days and weeks after treatment makes a real difference in your outcome.
Your eye will likely feel irritated and appear red during the first day or two after CPC. Mild to moderate soreness is common, and your vision may be blurrier than usual while inflammation settles. Resting at home with your head slightly elevated and using a cold compress on your closed eyelid can help ease swelling and discomfort. Avoid rubbing your eye even if it feels gritty, and wear sunglasses if light sensitivity bothers you, both indoors and outside.
Over-the-counter acetaminophen is usually sufficient to manage the aching or soreness that follows CPC. If we prescribe stronger pain medication, take it only as directed and for as long as needed. Inflammation inside the eye is expected after this type of laser treatment, so we will prescribe steroid eye drops to reduce it and protect your healing tissue.
- Use acetaminophen or any prescribed pain medication as directed
- Apply a cold compress for 10 to 15 minutes several times each day during the first few days
- Report any severe or worsening pain that does not respond to medication
- Follow surgeon-specific guidance before using anti-inflammatory pain relievers if you take anticoagulants or have kidney or gastrointestinal concerns
You will use several types of eye drops after your procedure, including steroid drops to control inflammation and, depending on your procedure type and our team's preference, antibiotic drops as well. We will provide a written schedule showing exactly which drops to use, how many times each day, and for how long. Phone alarms or a simple paper chart can help you stay consistent.
Continue any glaucoma drops you used before your procedure unless we tell you to stop. Do not change your medication regimen on your own, even if your pressure improves. We will guide you through any adjustments at your follow-up visits.
During the first week after CPC, avoid heavy lifting, intense exercise, or any activity that strains your head or raises pressure in your eyes. Swimming, hot tubs, and saunas are off-limits until we give you clearance, which is usually after several weeks. Light activities such as reading, using a screen, and gentle walking are generally acceptable if your vision allows and you feel comfortable doing them.
- No heavy lifting or straining for at least one week
- Avoid bending over, vigorous exercise, and yoga inversions
- Keep water, soap, and shampoo away from your treated eye for at least the first week
- Wear protective eyewear in dusty or dirty work environments
- Ask before resuming contact lens wear, typically several weeks after treatment
We will schedule follow-up visits one day and one week after your procedure to check your pressure and look for signs of inflammation or complications. Patients with very high baseline pressure, advanced glaucoma, or elevated risk for pressure spikes may need an even earlier check on the day of treatment. Additional visits at one month and three months allow us to assess how well your pressure is responding over time.
Pressure can continue to shift for weeks to months after CPC, so patience is important. We will taper your steroid drops gradually as your eye heals, and we will adjust medications if needed to keep your pressure in a safe range. Regular follow-up is one of the most important parts of your long-term glaucoma care.
Results, Risks, and Warning Signs
CPC is an effective tool for managing difficult glaucoma, but like any medical procedure it carries risks. We will always walk you through both the potential benefits and the possible complications before you consent to treatment.
Many patients experience meaningful reductions in eye pressure after CPC, though results vary considerably based on glaucoma type and severity, the specific technique used, and how well you follow aftercare. Some patients achieve excellent long-term control, while others see pressure gradually climb again over months or years and require additional treatment. Micropulse CPC in particular has shown encouraging pressure reductions in clinical studies, with some patients able to reduce or stop oral glaucoma medications after treatment. Your individual outcome depends on many factors, and we will set realistic expectations together at your consultation.
If your pressure does not drop enough after the first CPC session, a second treatment is often possible after your eye has fully healed. Repeat CPC can provide additional benefit without dramatically increasing risk for most patients. Some people eventually need a different type of glaucoma surgery, such as a trabeculectomy (a procedure that creates a new drainage channel) or a tube shunt (a small implant that redirects fluid out of the eye), if CPC alone is not sufficient.
- Repeat CPC may be scheduled several weeks to months after the first session if pressure remains elevated
- Combining CPC with continued glaucoma medications can help improve overall control
- Tube shunt surgery or trabeculectomy may be considered if CPC does not achieve enough pressure reduction
- We will continuously reassess and update your treatment plan based on how your eye responds
Most side effects from CPC are temporary and include redness, swelling, and soreness in the days following treatment. More significant complications are less common but can occur, and their likelihood depends on the technique used, the health of your eye, and the subtype of glaucoma being treated. We discuss these risks with you in full before your procedure so you can make a fully informed decision.
- Temporary pressure spike in the hours or days after treatment
- Prolonged inflammation inside the eye requiring extended steroid treatment
- Very low eye pressure, which can lead to fluid accumulation under the retina
- Vision decrease that may be temporary or lasting, with risk varying by technique and baseline eye condition
- Cystoid macular edema, a type of retinal swelling, particularly in higher-risk eyes or after ECP
- Cataract progression in patients who still have their natural lens, especially with significant inflammation
- Corneal swelling or surface irritation
- Phthisis bulbi, a rare condition in which the eye shrinks, associated mainly with aggressive or repeated continuous-wave treatment
- Retinal detachment or internal bleeding, both rare
- Sympathetic ophthalmia, an extremely rare but serious immune reaction that can affect the untreated eye
While most recoveries proceed without serious problems, certain symptoms after CPC mean you should contact us or seek urgent eye care right away. Do not wait for your scheduled follow-up if you experience any of the following.
- Sudden or significant vision loss, or a rapid increase in blurriness
- Severe pain that does not improve with prescribed medication
- New floaters, flashes of light, or a curtain or shadow across your vision
- Heavy discharge, intense redness, or signs of infection
- Nausea and vomiting that accompany eye pain
- Fever or worsening systemic illness alongside escalating eye symptoms
- Persistent vomiting or inability to keep medications down after sedation
If you cannot reach our office right away, please go to an emergency care facility. Early intervention for these types of complications can make a meaningful difference in preserving your vision.
Frequently Asked Questions
These answers address common questions that go beyond what is covered in the sections above. If you have a question not listed here, please ask during your consultation.
The procedure itself is usually well tolerated because we use both numbing drops and a local anesthetic injection to block pain. Afterward, you may feel soreness similar to a bruise that typically responds well to over-the-counter acetaminophen. Most discomfort eases within a few days, though patients who have continuous-wave CPC may experience more significant pain than those who have micropulse treatment, so discussing technique options with your eye doctor matters.
Some patients notice a pressure drop within the first few days, but the full effect typically develops over several weeks as inflammation settles and the ciliary body adjusts. It is also possible for pressure to temporarily spike in the days right after treatment before it begins to decrease. This is one reason we schedule close follow-up early on, so we can monitor your pressure trend and adjust medications quickly if needed.
Yes, repeat CPC is common and generally safe when the first session does not achieve adequate pressure control. We typically wait several weeks to a few months between sessions to allow your eye to fully heal and to accurately measure the result of the first treatment. Some patients require multiple sessions over the course of their glaucoma management, and this does not mean your treatment has failed. It simply reflects how variable glaucoma can be over time.
Many patients continue using at least some glaucoma drops after CPC, though the number or frequency may be reduced as your pressure improves. Whether you can reduce or eliminate drops depends on how much pressure lowering CPC achieves for you specifically. Never change or stop your drop regimen without checking with us first, because stopping drops prematurely could cause your pressure to rise before we have confirmed it is safe to do so.
Transscleral CPC does not require cutting into the eye or creating a drainage pathway, which generally makes it a less invasive option than trabeculectomy or tube shunt surgery. However, those surgeries may provide more predictable or durable pressure control in some patients. CPC tends to be preferred when other approaches have failed, when surgical risk is high, or when a less invasive option is needed first. Our team weighs your glaucoma type, eye health, and overall goals when recommending the most appropriate path forward.
Most complications from CPC develop in the weeks or months right after treatment rather than years later. Over the longer term, the most common concern is pressure gradually rising again, which may call for repeat treatment or a different surgical approach. Patients who needed prolonged steroid drops for post-procedure inflammation may also be at increased risk for cataract formation over time. Consistent follow-up care allows us to catch these developments early and respond appropriately before they affect your vision.
Schedule a Glaucoma Consultation at Rhode Island Eye Institute
If you are living with glaucoma that has been difficult to control with medications or other treatments, our team is here to help. Rhode Island Eye Institute offers advanced glaucoma care, including cyclophotocoagulation, led by fellowship-trained specialists who are committed to finding the right approach for your unique situation. We welcome patients from across Rhode Island and beyond, and we look forward to partnering with you to protect your vision for the long term.