Rubeotic / Neovascular Glaucoma (RG)
This type of glaucoma usually follows a severe retinal vein blockage or severe diabetic eye disease. The animation here explains the condition if you are online, but this text is helpful if you need to print out a leaflet.
The aqueous is made in the ciliary body in the middle chamber of the eye, and flows through to the front chamber. It then flows through a drainage system, the 'trabecular meshwork', out of the eye into the blood stream.
The healthy eye sees as light enters the eye and hits the retina.
The 'retina' is the 'film' of the eye, just like the film of a camera. Blood travels through the optic nerve in arteries to reach the retina,
and is normally drained away out of the eye in veins.
The front chamber of the eye is filled with a clear watery fluid, the aqueous or (aqueous humour). (Aqueous has nothing to do with tears.)
The aqueous fluid is made in the ciliary body in the middle chamber, then flows to the front chamber, then out of the eye through the trabecular meshwork (the drain of the eye).
a healthy retina a retinal vein occlusion photo.
Retinal veins drain the blood out of the eye (see). They may become damaged by high blood pressure, smoking, glaucoma or an unhealthy diet.
One day the vein can block, and then blood my leak out. The retina then 'floods' like a river overflowing, and it becomes thick like a sponge. The retinal damage unfortunately makes the sight very poor in the affected eye.
Here the VEGF makes tiny blood vessels grow, which we call 'new blood vessels'.
As the drain is blocked, the aqueous is trapped in the eye putting the eye pressure up. This may cause corneal oedema as below:
The corneal oedema prevents the laser light reaching and burning the retina.
(The cornea will clear when the pressure drops.)
Laser will stop the blood vessel growth in the drain/trabecular meshwork.
After such a severe retinal vein occlusion as above, but also severe diabetic retinopathy, this condition may develop. The process is very similar. It may also follow other conditions, such as a 'total' retinal detachment or poor blood supply to the eye..
This damaged or 'sick' retina produces growth chemicals, call growth factors. We call this damaged retina 'ischaemic'.
The growth chemicals spread to the front of the eye. Here they reach the drainage system (the trabecular meshwork). The main growth factor is VEGF, that is vascular endothelial growth factor. See animation.
At about the same time the blood vessels grow in the drainage system, they grow on the surface of the iris, where your doctor can see them.
These tiny blood vessels then block the trabecular meshwork (drainage meshwork), so the aqueous fluid cannot leave the eye. As the fluid cannot escape, the pressure goes up, like a tyre being pumped up too much.
The eye cannot burst, but it becomes much harder. In a way this is a 'faulty healing process'.
RG is often a painful condition; the high pressure causes the pain and inflammation. The eye can become painful and blind eye in about ½ the people affected. Luckier people have the condition without pain.
Laser of the retina, anti-VEGF treatments, and cyclodiode laser of the ciliary body are the main treatments for this condition. Treatment is best started before RG develops: when the eye is painful and blind treatment is very difficult, and often not very successful.
When the pressure is very high the cornea becomes cloudy.
Laser burns the sick 'ischaemic' retina and reduces the VEGF production. With less VEGF the blood vessels stop growing and the drain opens a little. Several thousand retinal laser burns are needed, in 3-5 sessions.
If very successful, the blood vessels stop growing, the trabecular meshwork drain opens up, and the pressure goes down. The sight will be permanently reduced but should not get worse still, and the pressure should stay down.
Retinal laser is not possible if the pressure is so high that the cornea becomes cloudy.
The pressure may be high because
- there are growing blood vessels in the trabecular meshwork: anti-VEGF treatment is needed.
- or there is scarring of the trabecular meshwork: cyclodiode laser will help.
If retinal laser is not possible, or if the eye needs extra treatment in addition to laser, anti-VEGF treatment may help (such as Avastin).
This injection of anti-VEGF treatment such as Avastin, is very helpful. It stops the blood vessel growth in the drain/trabecular meshwork), and then the drain can opens up and the pressure can go down for few weeks. This gives time for laser and other treatments to work. Sometimes more than one treatment is needed, but seldom more than three. As soon as the anti-VEGF treatment drops the pressure, retina laser is needed...anti-VEGF treatment is only a temporary measure to lower the pressure.
Avastin will only help if the blood vessels in the trabecular meshwork are actively growing; it will not work if there is scarring. Anti-VEGF treatment is an 'antigrowth' [of blood vessels] chemical, it won't eliminate scars.
If there is scarring of the trabecular meshwork, cyclodiode laser may be needed.
Cyclodiode laser stops the ciliary body producing aqueous (the ciliary body is 'tap' that produces the aqueous as above) and this will lower the pressure. Sometimes 2-3 treatments are needed.
Drops may help in this condition at the beginning. These include steroid eye drops such as Dexamethasone, and drops to dilate the pupil, such as atropine. Generally, these are only used for a few months, as they have many side effects if used for longer. See animation.
A typical treatment plan, standard treatment for rubeotic glaucoma
- Acetazolamide 250mg 4 times a day
(reduce dose if it makes you ill; consider half tablets (125mg) or quarter (62.5mg). It can make you feel sick or sleepy etc, occasionally very ill indeed [ it must be stopped then])
- Latanoprost at night
- Brinzolamide twice a day
- Timolol 0.25% LA once a day
- Or instead of Brinzolamide and Timolol…..use dorzolamide and timolol (Cosopt) twice daily (this had two drugs in)
- Timolol must be stopped if there is asthma
- Dexamethasone four times day (preservative free or Maxidex)
- Atropine1% twice daily: Atropine makes your mouth dry and must be kept away from children.
- Always bring drops every visit
- Cyclodiode laser if retinal view poor
- PRP laser if retinal view good
- anti-VEGF injections (Lucentis or Avastin)
Eyes with good sight
Eyes with good sight with a high pressure may benefit from tube surgery, not discussed here.
Traditionally RG has been a very serious condition and they eye often does not recover its sight, but with these new treatments sight is more likely to improve. The injection will be needed early, as soon as possible after the condition is diagnosed Almost certainly laser will still be needed as well. animation .
Many doctors prefer to laser early in this condition. That is they laser all patients with a very severe retinal vein occlusion. But of course not all these patients would develop rubeotic glaucoma. So that means 100 patients will have to be lasered to prevent 50 from getting rubeotic glaucoma. Even with laser a few patients, perhaps 5, will still develop rubeotic glaucoma, but laser will prevent 45.
Other doctors, and the Royal College of Ophthalmologists, recommend
waiting till rubeotic glaucoma (or at least the blood vessel growth
on the iris and trabecular meshwork) develops, and then carry out
the laser. But unfortunately treatment at this stage is not always
successful. The author of this page prefers early laser, but knows
many experts who prefer waiting for the rubeosis.
Basically, everyone whose sight has reduced to 6/60 (20/200) or worse has a high risk of developing rubeotic glaucoma. There is a higher risk if you are diabetic.
If you see 6/24 (20/80) or better you have a small risk and may often be fine without laser. If you see 6/36 (20/120) there is an intermediate risk.