When drops and medications cannot maintain optimum intraocular pressure, surgeons may choose laser surgery. The type of laser surgery depends on the severity of glaucoma and normally this procedure is done on an outpatient basis in the eye clinic. The eyes are numbed so that there is little or no pain. Here are the various types of laser surgeries used by ophthalmologists to treat the condition
Selective Laser Trabeculoplasty (SLT)
Selective Laser Trabeculoplasty (SLT) is used for treating primary open-angle glaucoma. Approved by FDA* in 2001, it is a safe procedure that lowers the intraocular pressure and increases the fluid drainage. SLT uses low-levels of energy to pinpoint areas of the trabecular meshwork. It takes just a few minutes and has the following advantages:
- Minimal side effects
- Minimal damage to the surrounding tissue
- The procedure can be repeated (if required)
Argon Laser Trabeculoplasty (ALT)
Just like SLT, ALT is also used for treating primary open-angle glaucoma. Here, the fluid channels of the eye are opened by the laser beam thereby helping the drainage system to work better. During ALT, the trabecular meshwork is targeted by an argon laser beam and generally half the fluid channels are initially treated. The other fluid channels are treated in a separate session, if the initial session does not have the desired therapeutic effect.
Micropulse Laser Trabeculoplasty (MLT)
Similar to SLT and ALT, MLT aims to provide the desired pressure-lowering effects with less energy. It uses a specific diode laser with a longer pulse length than SLT. The temperature rises slowly as laser energy is delivered in short microburst over an extended period.
Laser Peripheral Iridotomy (LPI)
LPI is recommended for patients suffering from narrow-angle glaucoma. Narrow-angle glaucoma happens when the angle between the cornea and the iris is very small because of which the iris blocks the fluid drainage increasing the intraocular pressure. LPI removes the pupillary block by allowing the aqueous to pass into the anterior chamber from the posterior chamber directly. In patients suffering from narrow-angle glaucoma, the surgery should ideally be performed after intraocular inflammation and intraocular pressure are controlled, but sometimes needs to be done in the acute stage.
Diode Laser Transscleral Cyclophotocoagulation (Diode CYC)
Diode CYC is usually recommended when other conservative surgeries such as tube surgery or trabeculectomy filter surgery have failed to yield results. It is also used if vision is extremely poor. Here, laser is used to destroy a part of the ciliary body that produces the aqueous humour. Destruction of the ciliary body decreases the production of fluid in the eye and reduces the intraocular pressure.
Laser surgeries help lower the eye's intraocular pressure. It is important to remember that the length of time till the pressure is low depends on the type of glaucoma, the type of surgery and many other factors. In some cases, one might require repeat laser procedures, or indeed formal filtration surgery, to lower the pressure adquately.
Risks of Surgery
As with any surgery, there are certain risks associated with laser surgery. In some cases, patients may experience a short increase in IOP. Patients undergoing Diode CYP are vulnerable to too much dropping of IOP. Use of anti-glaucoma and other medication before and after surgery controls the risk. There are also small chances of developing cataracts. But the advantages of surgery by far outweigh the risks.
Choice of Procedure
Your eye specialist will advise you about which procedure is appropriate for you and is most likely to succeed. This depends on the type of glaucoma you have, the configuration of the structures within the eye and the amount of reduction in intra ocular pressure that is aimed for. Your eye specialist will consider all these and then discuss appropriate interventions with you.
*FDA = Food and Drug Administration of the USA.