This is a type of laser treatment
for neovascular age-related macular degeneration (CNV in ARMD). This
program is in the process of winding down, as the
new drugs take over.
A dye is injected
intravenously with a simple injection into the patient's
arm. The dye passes through the blood to stick to the CNV blood
vessels in the retina. 13 minutes later
a gentle 'cold' laser is shone into the eye, pointing at the CNV, and
this activates the dye. The dye then 'burns' the CNV blood vessels. |
Anti-VEGF are more effective and more popular. In specialised departments combination treatment may be recommeded, that is anti-VEGF and laser PDT. |
- Patients are asked to come to a special laser clinic
- the vision is measured, then the pupils dilated
- sometimes the visit is combined with a fluorescein angiogram, but
sometimes the angiogram is carried out the week before
- if the fluorescein angiogram shows the disease is still active, PDT
laser is recommended (although this will
change)
- a brief medical history is taken with blood pressure, a canula is inserted into the elbow vein, like having a routine bood
test
- a little saline is injected, and then the patient is attached to
a pump and the dye (porphrin) infusion
- the dye is injected slowly over about 10 minutes, anaesthetic eye drops are given, & at the same time the doctor sets up the laser
- immediately after the injection the patient walks over to the laser,
which is given at the slit lamp
- after a 3 minute wait
- the laser is given over 83 seconds (it is simply a type of
bright light shone into the eye through a special contact lens, and
it is focused over the area ov CNV)
- if a large area (or the other eye) needs treatment, the laser is
focused on the respective macular area for another 83 seconds
- the patient will be transfered to the recovery room, be offred a
cup of tea, blood pressure is re-recorded, and goes home 30 minutes
later
- the patients MUST BE COMPLETELY COVERED and no part of the skin exposd
to sunlight for 48 hours. Otherwise the respective skin will be burnt
by the sunlight. Public transport is not ideal if it involves walking
outside, although it is fine if combined with a taxi to the station
etc.
- 1% of patients get back pain, 1% lose vision after the laser for
a short time and this recovers
- a blood pressure of less than 140/80mmHg will help to slow down the
disease. A high blood pressure will encourage bleeding. Smoking will
make it 4 times more likely the CNV will NOT respond to the PDT laser.
- people
having PDT using warfarin are more likely to notice macular haemorrhages. Usually the warfarin
is need to prevent an even more serious medical problem, and should
not usually be stopped. But a LOW BLOOD PRESSURE is likely to reduce
the risk of bleeding considerably. Keep BP <140.
- the next visit is 3 months later for re-assessment, and the procedure
repeated if still active
- 5 treatments may be needed over 15 months, the average is 3 treatments
- occasionally the PDT activates the CNV leading to loss of more sight,
and this can happen over the next few weeks.
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