Lasers can lower eye pressure, or keep it from rising, without cutting into the eye. Which laser you need depends on the type of glaucoma you have.
Laser iridotomy
For: narrow angles, with or without glaucoma, and angle-closure glaucoma.
The laser makes a tiny hole near the edge of the iris. Fluid can then flow through it instead of being trapped behind the iris, and the iris falls back from the drainage mesh, widening the angle.
It is used to treat an acute attack and to prevent one in eyes at risk, including the other eye of someone who has had an attack. It works best on angles that have not already sealed.
Laser iridoplasty
For: narrow angles that stay narrow after an iridotomy.
The laser makes small, gentle burns around the edge of the iris. As they heal, the tissue tightens and pulls the iris away from the drainage mesh. It takes a little longer than an iridotomy and feels much the same.
Laser trabeculoplasty (SLT)
For: open-angle glaucoma.
Here the laser is aimed at the drainage mesh itself. Selective laser trabeculoplasty (SLT) uses low-energy pulses that do not burn the tissue. They prompt the body to renew the lining of the mesh, which helps fluid drain more easily. An older version, argon laser trabeculoplasty (ALT), works in a similar way. If the pressure drops enough, you may need fewer drops, or none. The effect can wear off over time, and the treatment can sometimes be repeated.
A few people have mild redness or tenderness for a day or two. There are usually no restrictions afterwards.
What having the laser feels like
- Numbing drops are put in your eye.
- You sit at the laser with your chin on a rest. A strap may steady your head.
- The doctor holds a small contact lens on your eye to focus the beam.
- You see a red aiming light and hear a click with each pulse. Some people feel a brief, dull ache.
It takes a few minutes. Your vision may be blurred for a short while afterwards from the gel used with the lens. You may be given drops for a few days, and you can usually carry on as normal.
Lasers for difficult cases
- Cyclophotocoagulation. When the pressure stays very high despite other treatment, often in an eye with little sight left and a lot of pain, a laser applied through the white of the eye reduces how much fluid is made. It is done in the operating room under local anaesthesia, and the aim is mainly comfort.
- Pan-retinal photocoagulation (PRP). In severe diabetic eye disease and some blocked retinal veins, abnormal blood vessels can grow into the drainage angle and close it. Laser treatment of the outer retina makes those vessels less likely to grow. It works best before they appear.
Risks
Laser treatments are low-risk but not risk-free. The pressure can rise for a short time afterwards, inflammation may need drops, and the effect may fade. Your doctor checks your pressure afterwards and at follow-up visits.
This guide explains; it does not diagnose. Your doctor’s advice about your own eyes comes first.