Cyclophotocoagulation (CPC) is a form of eye laser surgery conducted to perform cyclodestruction (the destruction or shrinkage of ciliary tissue). This helps to decrease intraocular pressure and control glaucoma. Glaucoma is a progressive eye disorder caused when there is a higher than normal intraocular pressure (IOP). IOP results when there's a blockage within the eyes’ passage, causing the aqueous humor (a thin, clear fluid that provides nutrition to eye tissues) to build up and cause too much pressure within the eye. Glaucoma is a major cause of blindness in people over 60 years of age.
The procedure is the only surgical process that seeks to reduce the amount of aqueous humor produced. Cyclodestruction is responsible for the reduced aqueous humor secretion.
Due to its cyclodestructive nature, CPC is normally performed when no other forms of glaucoma surgery, such as tube shunt surgery or trabeculectomy, have been successful or when the patient has significant vision loss. If the patient already has some form of vision loss, CPC will not help regain it.
For an eye specialist to recommend CPC, the patient is likely to have mild to moderate glaucoma, use eye drops to control glaucoma, and have a large cataract. Indications for ECP are:
- Primary open-angle glaucoma
- Angle-closure glaucoma
- Pseudophakic glaucoma
- Neovascular glaucoma
- Paediatric glaucoma
- Glaucoma associated with retinal surgery
- Glaucoma after penetrating keratoplasty
The following factors determine the success of CPC:
- The patient’s age
- Eye surgery history
- The type of glaucoma
- Other conditions such as hypertension or diabetes
Preparation & Expectation Before Surgery
The patient is advised to stop taking certain medications such as those containing aspirin, arthritis medicine, and blood thinners, a week before the procedure. People with diabetes will receive specific instructions on how to take their insulin from the specialist. Patients are sometimes required to withhold food and drink for six hours before CPC. No blood tests are done before the surgery.
CPC is an out-patient procedure, therefore, the patient is free to leave afterwards. However, it is recommended that they have someone else drive them home due to the effects of the numbing eye drops.
Types, Purpose & Procedure
There are three types of CPC:
1. Transscleral Diode Cyclophotocoagulation (TCP)
With this type of CPC, a laser beam is placed just outside the sclera (the white of the eye). The melanin in the ciliary body absorbs the laser beam. 15 to 30 laser treatment spots are administered. It works well, but it has too many associated risks.
2. Micropulse Transscleral Cyclophotocoagulation
This type of CDC is similar to TCP, the only difference being that the laser energy is cut up into short pulses (micropulse). This usually helps reduce the possibility of inflammation and damage to other eye tissues.
3. Endoscopic Cyclophotocoagulation (ECP)
With this type of CPC, a tiny endoscope is put through an incision in the cornea. The scope is used to see the ciliary processes, and then the laser is applied to the area. It is considered safer than TCP because the optician can see precisely where the issue is.
During the surgery, the patient is requested to comfortably lay down, with a pillow supporting his/her head. A caregiver will clean the area around the eye and administer numbing eye drops. In some cases, some medicine may be administered intravenously or orally. After the numbing eye drops take effect, the ophthalmic surgeon applies a laser light through the sclera (the white of the eye) to the ciliary processes, destroying the structure. The surgery takes 10-20 minutes.
Risks, Side Effects & Complications
Due to the numbing eye drops, the patient may experience blurry vision for a few hours, but this will eventually go away. Other side effects include sensitivity to light and postoperative pain, which both go away naturally.
Some of the complications that may arise from CPC include:
- Prolonged ocular inflammation
- Macular edema - The build-up of fluid in the retina
- Phthisis bulbi - A shrunken eye globe that results in function loss
- Loss of the whole eyeball
- Intraocular hemorrhage/bleeding especially in patients with neovascular glaucoma
- Decreased vision or permanent vision loss
- Low IOP (hypotony)
- Sympathetic ophthalmia - A very rare condition where there is inflammation of the uveal tract after trauma or eye surgery.
- Retreatment due to failure to lower eye pressure
After Care, Recovery & Results
After surgery, the patient will receive eye drops to decrease swelling and redness. This inflammation may last up to two weeks. The patient may be required to go back to the eye specialist’s office a day after the procedure is done, with subsequent check-ups.
For the next few weeks, the patient will be required to wear an eye patch and sunglasses outside to help reduce light sensitivity. It is also advised that the patient avoid wearing eye make-up, rubbing the eye, swimming, and strenuous exercises.
If the patient’s IOP does not reduce to an average level or if eye pain persists, CPC may be repeated until the desired results are achieved. Ciliary processes may also regenerate requiring repeat surgery. In this case, the eye specialist can titrate subsequent treatments to suit the patient’s specific needs. For the operation to be considered effective, IOP should decrease by 20 to 30%.
In case the patient was using glaucoma drops before the procedure, their eye doctor will advise on whether they will continue or modify, according to the type of glaucoma and its rate of progression