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Micropulse and CPC Laser

Cyclophotocoagulation (CPC) is a laser treatment that lowers eye pressure by treating the ciliary body, the tissue that makes the fluid inside the eye. Most glaucoma treatments help fluid leave the eye. This one turns down the faucet instead. It is done from the outside, through the white of the eye, with no cuts or stitches.

There are two main kinds, and the animation shows both: micropulse, which delivers the laser in short, gentle bursts, and standard CPC, which delivers a stronger, steady pulse at each spot. Press Play to watch, or tap a step to go through it at your own pace.

The animation needs JavaScript. The explanation below covers the same thing.

How it works

The ciliary body is a ring of tissue hidden behind the iris, just under the white of the eye. It makes the eye's fluid all day and night. A small probe is rested on the white of the eye, just behind the edge of the cornea, and the laser energy passes through the wall of the eye to the ciliary body underneath. The treated tissue makes less fluid, so the pressure falls. On the eye pressure sink, this is the faucet being turned down.

Micropulse and standard CPC

  • Micropulse. The laser switches on and off many times a second, so the tissue rests between bursts and heats up less. The probe is swept slowly back and forth along the upper half of the eye and then the lower half. It causes less inflammation and can be used earlier in glaucoma, including in eyes with good vision. It is done with numbing drops and sedation. Its effect is usually milder, and it is more likely to need repeating.
  • Standard CPC. The laser is delivered as a steady pulse at each of a row of spots around the eye. It is a heavier treatment: it lowers pressure more, with more inflammation afterward and somewhat higher risks. It is used mostly in eyes with poor vision, when other treatments have not controlled the pressure. It is done with a numbing injection beside the eye.

Both skip the two sides of the eye (the 3 and 9 o'clock positions), where nerves and blood vessels run.

Why your doctor might suggest it

  • Pressure is still too high despite drops and SLT laser
  • Surgery such as a trabeculectomy or tube shunt has not worked well enough, or is not a good option for your eye or your health
  • To reduce the number of drops you need
  • To add to the effect of an earlier operation
  • To relieve pain from very high pressure in an eye with poor vision

The day of the laser

  1. It is done in a procedure room or operating room.
  2. Micropulse: you are given sedation through an IV so you sleep lightly for a few minutes, and numbing drops are placed on the eye.
  3. Standard CPC: the eye is numbed with an injection of anesthetic behind the eye, which also keeps it still. You may feel pressure during the laser, but it should not hurt.
  4. The probe is placed on the white of the eye and the laser is applied. The treatment itself takes a few minutes.
  5. The eye may be patched for the rest of the day.

You will need a driver. Usually one eye is treated at a time.

After the laser

  • Aching, redness and blurry vision for a few days are expected. Over-the-counter pain relievers usually are enough.
  • You will use an anti-inflammatory (steroid) drop for at least a month, stepping down a little each week:
    • After micropulse: four times a day for a week, then three, then two, then once a day, about four weeks in all.
    • After standard CPC: eight times a day for a week, then six, four, three, two and one, about six weeks in all.
  • The Post-Op Schedule page makes a printable day-by-day chart of these drops.
  • Your doctor may change this schedule for your eye. Sometimes a drop that keeps the pupil dilated is added to keep the eye comfortable.
  • Keep using your glaucoma drops unless you are told to stop. The laser takes about a month to reach its full effect, and drops are adjusted after that.
  • There are usually no activity restrictions after the first day.
  • If the pressure is not low enough, the laser can be repeated.

Call the same day if you have severe pain, a marked drop in vision, or increasing redness.

Risks

  • Inflammation inside the eye is the most common effect. It is treated with drops and is milder with micropulse.
  • Blurred or reduced vision, usually temporary. Lasting loss of vision is uncommon and more of a concern with standard CPC.
  • A pupil that stays larger than before, in some eyes.
  • Swelling of the central retina (macular edema), treated with drops.
  • Pressure that falls too low, which is rare but serious, and is the main reason standard CPC is used carefully.
  • Not enough effect, so the laser is repeated or another treatment is added.

Questions worth asking

  • Is micropulse or standard CPC planned for me, and why?
  • How much do you expect my pressure to fall?
  • How likely is it that I will need it again?
  • Will I still need my drops afterward?
  • What should I expect in the first week?