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Laser treatment for glaucoma (PI / SLT) PDF Print E-mail
Written by Administrator   
Tuesday, 22 September 2015 00:00

Laser treatment for glaucoma is used in a variety of ways. Laser can be used for angle closure, when it is applied to form a tiny opening in the iris (known as an iridotomy), or laser is used to treat the ciliary body (either externally or internally), or laser can be applied to the drainage angle (selective laser trabeculoplasty) to lower eye pressure.

YAG laser iridotomy

Laser iridotomy is performed as a preventative measure against, or as treatment for, narrow angle glaucoma. The purpose of the laser is to reduce the risk of sight loss. Vision can be affected quickly if the eye pressure rises very high. It is a relatively simple treatment nowadays, with more modern lasers delivering very little energy (eg 10-20mJ) to make a tiny opening in the iris. The iridotomy is usually less than 0.75 mm in diameter. The laser treatment typically takes less than 5 minutes, although drops are given beforehand (pilocarpine drops) in most cases so that the laser opening is positioned in the peripheral iris. Recovery after YAG PI is quick, typically 2-3 days. A short course of topical steroid drops after treatment may be given to keep the eye comfortable as there can be some sensitivity to light for a few days after treatment.

Details about the iridotomy treatment:

  • You will be asked to sign a consent form.
  • Anaesthetic drops will be put in the eye(s) that need laser.
  • Several individual laser applications are required, and this takes only a few minutes. Each spot is perceived as a bright flash of light.
  • Each laser application typically does not cause discomfort. Most people feel only a mild discomfort, rarely it is possible to feel pain.
  • The iris is a form of muscle and can bleed. If this happens, it can blur the vision for many days, but this is uncommon.
  • Iridotomy can sometimes cause glare / dazzle symptoms longer term (less than 5%).
  • Sometimes a second treatment is required.
  • You may be given drops or tablets after laser treatment for a few days.
  • You should tell your doctor if you have any drug allergies as this might alter the medication given.


laser iridotomy 3D model

3D model of eye with arrow indicating approximate size of iridotomy.

Selective laser trabeculoplasty

SLT treatment lowers eye pressure by treating the drainage angle - the trabecular meshwork (the trabecular meshwork is a thin strip of porous tissue found in the front of the eye). This type of laser typically lowers IOP (eye pressure) by several points, and lasts for years in most cases. Like all treatments for glaucoma, the effect can wear off in time. This is important to understand, as in many chronic conditions (for example like arthritis) the treatments are aimed to prevent the situation from getting worse (in the case of glaucoma by lowering IOP to a safe level), rather than from curing the condition. Unfortunately, any field lost from glaucoma is invariably permanent, however the good news is that every point of IOP lowering makes the risk of progression of glaucoma lower. SLT also helps to reduce the fluctuations in eye pressure noted moreso in glaucoma patients. For more information about SLT and different research papers, please click see here:

Notes about the SLT procedure:

  • You will be asked to sign a consent form.
  • Afterwards, most patients do not notice any pain of discomfort.
  • The effect of laser treatment can take many weeks (even 2-3 months) for a drop in eye pressure to be noted.
  • If you have a dry eye, please take lubricants a little more often 2-3 days before laser, as the can be a little drier with laser treatment.
  • SLT laser works well in around 2/3rd of patients, i.e. not in everybody. SLT is a very safe treatment, safer than all types of surgery, and therefore it is considered at an earlier stage in many cases.


SLT laser for glaucoma

SLT laser machine

Last Updated on Tuesday, 22 September 2015 18:05
What are the risk factors for glaucoma? PDF Print E-mail
Written by Administrator   
Sunday, 31 January 2010 03:49

There are several risk factors for glaucoma. Age is one of the main risk factors, i.e. the condition is more likely to affect you the older you are. Other risk factors include family history (The Baltimore Eye Survey found that open-angle glaucoma is increased approximately 3.7 times for those with a sibling with this most common form of glaucoma), and also race, high eye pressure, diabetes, eye injury, and steroid use.


Nerve fibre layer scan image (of optic nerve)

What are the different kinds of glaucoma? PDF Print E-mail
Written by Administrator   
Sunday, 31 January 2010 03:35

There are dozens of types of glaucoma. The most common form is "POAG" or primary open angle glaucoma. This is distinct from another major type of glaucoma - angle closure glaucoma. Some glaucomas arise secondary to other eye conditions, for example, pseudoexfoliation syndrome or pigment dispersion syndrome.

Primary angle closure glaucoma
is caused by contact between the iris and the drainage angle, which in turn blocks outflow of the fluid from the eye. This contact between iris and drainage angle is believed to gradually damage the function of the drain (the "trabecular meshwork") until it  is unable to drain fluid effectively, and then the eye pressure rises. In many cases, contact between iris and the meshwork causes the formation of scar tissue. These can cause permanent obstruction of aqueous outflow, and in some cases, the pressure may build up in the eye very rapidly causing pain and redness. The treatment for angle closure is initially for YAG iridotomy. Sometimes, laser iridoplasty may be performed, and otherwise rarely a surgical iridectomy is required for those with no cataract. Angle closure is often dealt with very effectively nowadays with cataract surgery as this procedure definitively opens up the drainage angle.

Developmental glaucoma

* Primary congenital glaucoma
* Infantile glaucoma
* Glaucoma associated with hereditary of familial diseases

Secondary glaucomas

* Inflammatory glaucoma
* Uveitis of all types
* Fuchs heterochromic iridocyclitis

* Phacogenic glaucoma
* Angle-closure glaucoma with mature cataract
* Phacoanaphylactic glaucoma
* Phacolytic glaucoma
* Subluxation of lens

* Glaucoma secondary to intraocular hemorrhage
* Hyphaema
* Haemolytic glaucoma

* Traumatic glaucoma
* Angle recession glaucoma: Traumatic recession on anterior chamber angle
* Postsurgical glaucoma
* Aphakic pupillary block
* Ciliary block glaucoma

* Neovascular glaucoma (see below for more details)
* Drug-induced glaucoma
* Corticosteroid induced glaucoma

Neovascular glaucoma is an uncommon type of glaucoma that is more difficult to treat. This condition may be caused by proliferative diabetic retinopathy (PDR) or central retinal vein occlusion (CRVO).


Prism used to measure eye pressure (Goldmann tonometry).


Last Updated on Sunday, 31 January 2010 03:56
What causes glaucoma? PDF Print E-mail
Written by Administrator   
Sunday, 31 January 2010 03:28

Although many cases of glaucoma are caused by high eye pressure, there are an increasing number of patients that develop damage to the optic nerve even with low eye pressures. Certainly, glaucoma is caused by high eye pressure, and also by other factors such as poor perfusion (i.e. blood supply) to the nerve. In other cases, glaucoma is caused by having a crowded drainage angle (narrow angle glaucoma).

There are many types of glaucoma; in most cases the exact cause of raised pressure is not identified infact. Sometimes glaucoma can be caused by injury to the eye, or by other eye conditions, or by the use of medications (e.g. steroids in just about any form). Generally, whatever the cause, glaucoma is treated similarly. Some types of glaucoma respond less well to medication, or less well to laser or surgery.

what causes glaucoma

Visual field of a patient with glaucoma.

How common is glaucoma? PDF Print E-mail
Written by Administrator   
Sunday, 31 January 2010 03:22

Glaucoma affects about 5% of those over the age of 65 (approximate estimate) and 10% of those over the age of 80. In other words, about 1 in 20 people over the age of 65 are affected with this condition, so it is a fairly common condition. Glaucoma is commoner in some communities, for example in those from West Africa, and those from the Caribbean. Glaucoma is commoner in some families, and many patients with glaucoma have family members with the condition. Many genes have been identified as causing glaucoma, however generally the condition is not passed on directly and often might skip a generation. Nevertheless, for example, if you have a brother or sister with the condition then the risk of developing glaucoma yourself is increased significantly.

glaucoma how common is it

Last Updated on Sunday, 31 January 2010 03:28
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