Panretinal photocoagulation (PRP) is a form of laser surgery done to manage proliferative diabetic retinopathy (PDR). It helps to prevent severe vitreous haemorrhage and retinal detachment. The laser is applied to the peripheral retina, delivering mild burns to coagulate the retinal pigment epithelium leading to tissue oxygenation.
Diabetic patients experience poor circulation to the retina, which sometimes causes the development of new and abnormal vessels, what is known as PDR. These abnormal vessels are frail and can cause scarring, retinal detachment, bleeding and permanent vision loss. Bleeding inside of the eye is known as vitreous haemorrhage. The surgery causes regression of these abnormal blood vessels which develop in the retina of diabetic patients. If these abnormal blood cells are left untreated, they can cause severe and sometimes permanent vision loss.
The procedure is also helpful in controlling other forms of retinopathy like ischemic retinopathy and retinal vein occlusion.
The procedure prevents the growth of new vessels and doesn't help to regain lost vision. PRP leads to some periphery vision loss as it spares the central macular area (saving central vision). The patient may also experience lower colour and night vision.
Proliferative diabetic retinopathy may reoccur even if the initial surgery is satisfactory. If new, abnormal vessels grow back, the patient may also suffer from glaucoma. Therefore, multiple PRP sessions may be needed over the patient's lifetime.
Also Known As
- Panretinal laser photocoagulation
- Scatter photocoagulation
- Standard panretinal photocoagulation
There are two types of lasers that the specialist can use during the procedure:
- Single spot laser
- Pattern scan laser - Creates two-dimensional patterns such as arcs and rings.
Before the Procedure
- The patient should take all their medications as usual before the day of the procedure.
- The patient can eat and drink regularly unless the specialist advises otherwise.
- If the patient is taking any medication, they are advised to have enough of their medication for the day of the surgery.
- Before the commencement of the procedure, the patient will need to sign a consent form.
- Following the treatment, the patient will be allowed to leave after two to four hours.
- The patient cannot drive after the surgery and will need to find another means to get home. This is because the dilating drops used during the surgery cause blurry vision for several hours after the treatment.
The patient will be ushered into the specially equipped laser room. The nurse begins by instilling some dilating eye drops into the patient's eye. This helps the specialist to see the back of the eye when carrying out the procedure. The patient's eye is then numbed with a topical eye drop. This may cause a slight tingle or burn. The specialist may also opt to inject an anaesthetic under the eye, reducing the chance of any pain or discomfort. The injection may briefly cause some pressure behind the eye and double vision, and in rare cases, result in temporary blindness. This is no cause for alarm.
The surgery may be done with the patient seated and their head held in a slit-lamp or with the patient lying back. The specialist uses an eyelid holder to keep the patient from blinking. The specialist uses a special laser (either argon or diode) to make multiple tiny, targeted laser burns in the retina. The burns seal the retina and halt the affected vessels from leaking or growing. As the specialist is creating the retinal burns, the patient will see bright flashes of light in their vision.
The initial treatment consists of about 2000 laser spots per eye. This is done in two or more treatment sessions. The procedure takes about 15-30 minutes, depending on the complexity of the treatment. The specialist completes the procedure by placing an eye patch over the eye.
Risks & Complications
Like any other surgery, pan-retinal photocoagulation comes with risks. When an experienced specialist does the procedure, the chance of developing risks are lower.
Possible side effects of the procedure include but are not limited to:
- Blurry vision - This typically lasts less than one week. However, a small number of patients will experience the blur forever
- Mild pain around the eye
- Diminished night vision
- Decreased vision due to swelling of the retina - This regulates back to the previous level in about three weeks or remains that way permanently.
- Altered colour vision
- Lower peripheral (side) field of vision
- Black eye
- Decreased contrast sensitivity
- Temporary light flashes
Possible risks include but are not limited to:
- Droopy eyelid
- Double vision
- Loss of vision
- Vitreous haemorrhage
- Macular oedema
- A repeat of the surgery
The patient should immediately seek medical attention if they notice any changes in their vision.
Aftercare & Recovery
The patient will need to wear the eye patch overnight and remove it the following morning. If they experience any pain, they can take over-the-counter pain medication. They should wear sunglasses when outside during the day to keep away harsh light from the eye.
The results of the surgery take several months to be apparent. The patient will be required to go back to the specialist's office in a few weeks. Here, the specialist monitors the patient's response to the procedure. During this follow-up appointment, a further PRP laser session may be scheduled if required.
PRP is not a cure. The patient must make lifestyle changes to keep their eyes healthy. Patients are advised to control their diabetes, cholesterol and hypertension.
The surgery lowers the chance of major vision loss by half, in patients suffering from proliferative diabetic retinopathy. PRP does not help their vision get better.
The patient may require multiple laser treatments throughout their lifetime to control the eye disorder. Even with treatment, some patients still eventually lose their vision.