Wet ARMD involves CNV growth and leakage under or near the macula. The CNV and he leakage damage the macula, causing loss of central vision.
The CNV, without treatment, often cause significant scarring and loss of central vision. The growth and leakage can be reduced/stopped with anti-VEGF injections in the eye.
- the drug (anti-VEGF injections) only really work for 4 weeks, and then the effect wears off
- the leakage/growth starts 4 weeks before visual changes
- this means visual changes (distorted/wavy/patchy central vision) follow CNV growth by 4 weeks and so they cannot be relied on to detect very early disease.
- The only practical way of detecting early disease is with OCT.
- As the drugs work for 4 weeks, 4 weekly OCTs are needed to detect early disease.
- This leads to a massive number of patients visits and OCTs, too many for doctors to examine. Various units have trained technicians to carry out and interpret the OCTs, and Good Hope is trying to develop such a service
- When OCTs are cheaper these may be carried out by optometrists, and eventually at home, but until the OCT software can interpret the images with a ‘computer’, a person has to interpret the OCTs
- In practice then, after the first 3 injections (i.e. one every month for 3 months, are needed at the beginning) every patient has either an OCT or injection or both every 4 weeks
- After the first 3 months, patients then attend monthly for an OCT,
- and if there is fluid, an injection is arranged as soon as possible
- �if there is no fluid, the OCT repeated 4 weeks later
- It would be convenient for the patient if the injection could be carried out at the same visit as the injection. In practice this has been difficult for us to arrange as we are not sufficiently organised, but also the number needing the injections is so unpredictable the service becomes difficult to manage.
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- Our technician who does the OCTs is just about to be ready to grade the scans without direct supervision, taken 6 months to train
- Has been supervised for the 6 months
- She will enter the data onto Medisoft our system...takes 10 minutes/patient!!!!!!!!!! This will generate GP letters and notes
- A clerk organises the visits
- 20 patients a week
- We include a few diabetics ...monitor cme; a few soft drusen in smokers (i.e. high risk, 3 month review)
- Scans are monthly if the last injection was in last 6 months, otherwise intervals progressively extend
- Patients can ring up for an OCT if they notice visual symptoms
- Symptoms come 4 weeks after CNV..so we have to OCT to detect the CNV
- Patients are invited back for a further OCT 4 weeks after every injection
- The one problem is bilateral... when we inject but only one eye we should OCT the other eye
- We need to ask the technician to address smoking and blood pressure if she is the only person seeing the patient
- Of course we know we might be missing the very early case with a tiny haemorrhage and no visible OCT changes, but the proportion of these is small
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When the technician is ‘qualified’ to interpret the OCTs,
- The technician and doctor will still grade some OCTS together, as part of the audit process
- To interpret ‘borderline’ OCT, when it is difficult to make a decision
- We need to develop the service further and try and grade patients
- Some patients probably need anti-VEGF injection every month (call this group e)
- Some people may need them only occasionally (call this group o)
- Many patients will be in between (call this Grade ib)
- If there is a lot of fluid, 3 injections are probably needed to flatten the retina
- If there only a little fluid, and the patient is in group o, only one injection is booked
- If there is a medium amount of fluid, 2 injections are booked
- If it were possible to grade patients:
- Grade e would not need OCTs monthly, they would attend for injection only, saving clinic /patients time/money making it easier to plan (the fellow eye night need OCT, perhaps at the same time as the injection of the eye being treated
- Grade o patients would generally just need a an OCT occasionally
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If one eye is having injections we must remember to OCT the other eye. E.g. At present, we do not do this…..so if a patient is booked for 3 injections one after the other for the right eye at 4 week intervals, the left eye has no OCT for 12 weeks. We really should OCT the fellow left eye every 4 weeks.
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| CNV |
choroidal new vessels (i.e. neovascular
macular degeneration, or 'wet'). Blood vesssels growing through the retina
under the macula.
Also called CCNV. |
| CNVM or CNVm |
a choroidal neovascular membrane, that is a network of CNV,
although in practice this means the same thing as CNV |
| ARM |
age-related macular disease |
| ARMD |
age-related macular degeneration |
| PDT |
photodynamic
therapy (for classic sub-foveal neovascular ARMD ) |
| Occult CNV |
hard-to-see neovascular ARMD (based
on angiogram)
blood vessels growing under the retina and leaking�(but the leakage is late) |
| Classic CNV |
easy-to-see neovascular ARMD (based
on angiogram) blood vessels growing under the retina and leaking |
| dry ARMD |
thinning (and other changes)
of the central retina |
| PED |
pigment epithelial detachment,
a type of wet ARMD |
| Rip |
a pigment epithelial rip or tear |
| VEGF |
Vascular endothelial growth factor...the main chemical that
makes blood vessels grow in ARMD |
| RAP |
retinal angiomatous proliferation |
| OCT / scans |
optitcal coherence tomogram: a 3 dimensional photograph of the macula, called a scan |
| VMC |
Virtaul macular clinic..patients attend�for an OCT and the scan is interpreted later, and the patient contact if another anti-vegf injection is needed |
| wet (armd) |
wet age-related macular degeneration, with CNV as above (blood vessels growing and leaking under the retina, usually under the macula) |
| neovasularisation |
similar meaing to wet armd |
| macula |
the centre of the retina that sees detailed vision like faces and reading |
| anti-VEGF / injection |
drugs that reduce growth and leaking from the new blood vessels�under the retina in arnd, or on the retina in diabetes etc. They are gvine by injection into the eye |
| GP |
general pratitioner |
| drusen |
a type of aging change of the retina...tiny white spots/areas |
| � |
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