Nick Strouthidis MBBS MD PhD FRCS FRCOphth FRANZCO

LASER TREATMENT

Laser Peripheral Iridotomy (LPI) For Angle Closure

LPI is a form of laser used to reverse angle closure. The laser is administered at the slit lamp under topical anaesthetic. The procedure involves making a small hole in the iris, covered by the upper eyelid. This allows aqueous to pass from the back to the front of the iris and vice versa, thereby deepening the angle.

LPI is usually offered as first line treatment in people who have primary angle closure and primary angle closure glaucoma. Some patients with primary angle closure may present acutely with a very high IOP. LPI is required as part of the treatment in these eyes, along with drops to lower the IOP and drops that open up the angle.

LPI may cause inflammation, bleeding and elevated IOP but these effects are usually transient and can be treated with a short course of topical treatment. Serious complications such as visual disturbance are extremely rare.

LPI is not a suitable treatment for most secondary forms of angle closure as the hole will eventually close up, causing the IOP to go up again. In these cases, if an iridotomy is considered then it should be done surgically (a surgical iridectomy).

A more definitive treatment, which can be considered if iridotomy has not opened the angle sufficiently or if the patient already has significant cataract, is to perform lens extraction surgery with insertion of an intraocular lens. This has the effect of completely and definitively widening the angle. Please refer to the section on cataract surgery for more information.

Some patients with primary angle closure and primary angle closure glaucoma will effectively be treated just with peripheral iridotomy or lens extraction. Some may require eye drops to lower the IOP. Occasionally, patients may require further intervention (surgery or other forms of laser) if the glaucoma continues to worsen despite the aforementioned treatments.

Selective laser trabeculoplasty (SLT)

SLT is a laser treatment, delivered at the slit lamp (not in the operating theatre), which can be used to treat POAG and ocular hypertension.

During the treatment, laser energy acts on the trabecular meshwork, stimulating better aqueous drainage, thereby lowering IOP.

SLT is a useful treatment, because it is relatively simple and has a low risk of complication. The main risks are slight pain, inflammation, and failure. In some patients it can work for a prolonged period, in some cases giving to up to 5 years of IOP control without drops.

It is perhaps most effective at the earliest stages of the disease when POAG or ocular hypertension are first picked up. It can also be used as an alternative to drops or to try to reduce the number of the drops later on in the disease process, although success is more limited.

Cyclodiode

Cyclodiode is a procedure in which laser is applied on the surface of the white of the eye and this leads to a reduction of aqueous production by the ciliary body.

This can be a very effective method for lowering IOP but it needs to be done in the operating theatre with a local anaesthetic injection to prevent discomfort.

Cyclodiode may cause inflammation leading to a reduction in vision in some patients. It has therefore usually been reserved for refractory cases (in other words cases where all other treatments have failed) or blind painful eyes with high IOP. Increasingly now it is being used successfully in certain circumstances to treat high IOP in eyes with good vision.

Endocyclophotocoagulation (ECP)

ECP is a variation of cyclodiode treatment, whereby an endoscopic camera probe is introduced into the eye through a small wound and this allows a laser to be fired directly onto the parts of the ciliary body where aqueous is produced.

ECP is particularly useful as it can be combined with cataract surgery and so is therefore useful for lowering IOP in glaucoma patients undergoing cataract surgery.

Other ways to treat Glaucoma:

Medical Eye Drops

Surgery