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Yag PI – Glaucoma laser surgery

Yag PI Laser Treatment 

Yag PI laser treatment for glaucoma is the name of a laser treatment used to treat glaucoma.  Some refer to this as laser surgery for glacuoma but that would be a misnomer.  Laser peripheral iridotomy or Yag Pi full form is Nd: YAG (neodymium-doped yttrium aluminum garnet) Peripherial iridotomy.  Nd Yag is the name of the crystal used in the laser machine for treatment of glaucoma.  
 
Glaucoma are a group of eye diseaseses that have an increase in pressure inside the eye, which causes damage to the optic nerve and to the retina.
 
Acute narrow angle glaucoma, also called angle closure glaucoma or narrow angle glaucoma, is one of the two basic categories of glaucoma. The other category is open angle glaucoma.  It is the first category mentioned here that this laser peripheral iridotomy treats. 
 

HOW DOES ACUTE NARROW ANGLE GLAUCOMA OCCUR ? 

First let us try and explain the structure of the eye.  The ciliary processes makes the fluid that occupies the front part of the eye.  These ciliary processes are attached to the ciliary body.  And this ciliary body is present behind the iris which is the brown part of your eye.  Acute narrow angle glaucoma occurs in patients who have a shallow space between the cornea at the front of the eye and the colored iris that lies just behind the cornea.  This space is known as the anterior chamber.  

As the eye ages, the natural lens behind the pupil grows thicker.  Also as the eye ages the pupil becomes smaller, restricting the flow of fluid to the drainage site. The drainage site is at a place between the back part of the cornea and front part of the iris.  It’s also called the angle.  The actualy name of the structure that drains the fliud from the eye is called the trabecular meshwork.

If the pupil becomes smaller and the lens thicker there may arise a situtation where the round pupil presses against the lens which is just behind it.  If this happens, fluid flow from behind the iris through the pupil to the front of the iris stops.  The fluid can build up behind the iris, pushing the iris forward like a sail of a boat.  This ballooning of the iris can block the channel (angle) that allows aqueous fluid to drain. Because of this closed angle the fluid outflow from the eye stops.  A rapid rise in intraocular pressure can occur.  

This rapid rise of pressure is known as acute angle closure glaucoma.  If left untreated this acute rise of eye pressure can significantly damage the optic nerve.  This would result in irreversible loss of vision.

WHO UNDERGOES YAG PI LASER EYE SURGERY ?

 We examine the eye pressure as a routine check up in all patients who come in for an eye examination.  When we find raised eye pressure we first ascess the angle of the eye.  If this angle is narrow or the glcuaoma specialist feels that the narrow angle may be blocking the path of eye fluid on its way out, he may consider the Yag PI laser.  

Sometimes we see narow angle suspects where the angle appears narrow and pressure is borderline.  There may also be positive family history of glaucoma eye disease.  In these patients too, Yag laser treatment may be done.  These patients are known as primary angle closure suspects.

HOW DOES THIS LASER TREAT THIS TYPE OF GLAUCOMA ?

 As mentioned previously Yag PI full form is Yag Peripheral Iridotomy. This laser makes a new opening in the iris to allow the aqueous fluid to move more easily to the drainage site. The iris is the coloured part of the eye.  
 
Since the opening is at the very edge of the iris we call it “Peripheral iridotomy”. This laser treatment for this eye disease is usually performed in the doctor’s office. It is generally performed on both eyes because the risk of developing the condition in both eyes is high. 
 

HOW IS glaucoma laser surgery DONE ?

We call the patient 30 min before the Yag PI laser scheduled time.  Once the patient arrives we start putting Pilocarpine eye drops in one or both eyes.  These drops constrict the pupil or make it smaller.  This stretches the peripheral iris so that the procedure is easier and more effective.  These drops may cause a feeling of heaviness or eyestrain.  Fortunately this is only temporary and subsides over the next few hours.

Once that is done, the patient sits in front of the laser machine and places his or her chin on the chin rest.  An eye drop is put in the eye to numb the eye and then a contact lens is placed on the surface of the eye.  This may sound scary but because of the numbing drops this step does not hurt.

Then the doctor looks for spot on the iris which is thin.  Once the spot is found the lens is rotated to make sure it is in focus and the laser beam is fired.  Usually 2-4 shots may be needed.  The doctor knows that its done when he sees a burst of iris pigment flow into the Anterior chamber.  Eye doctors and glaucoma specialists also call this as pigment dispersion into the anterior chamber.

Treatment takes 5 to 7min for each eye.  

WHAT ARE THE PRECAUTIONS AFTER THE YAG PI ?

Once the laser treatment is done the patient is prescribed certain eye drops.  These eye drops are antiinflammatory and help in reducing the inflammation that occurs due to the laser.  As explained earlier, your eye doctor has caused an injury to your eye with that laser and the body is going to react to it.  The drops will help in reducing that reaction.  

Sometimes, because of a small amount of bleeding the vision may become blurred.  Even if this happens there is nothing to worry about as the blood clears up in a week and vision should return to normal.

CAN THE LASER PROCEDURE BE NEEDED AGAIN ?

Once the iris opening is made it is not necessary that it will remain open forever.  The reason for this is that the body considers this as an injury.  Like for any other injury the body tries and repairs this injury.  The repairing may happen by healing of the iris tissue and attempt to close the yag laser created opening. There is 20-30 % chance of the opening closing.  If that happens the laser may have to be repeated again.  
 

what happens if the pressure is not controlled after the laser ?

It is not necessary that the pressure redcues to the level that your treating eye doctor wants after the laser.  So even though the pressure has gone down it has not reached a level that your doctor wants.  In this situation your glaucoma specialist may prescribe certain eye drops that would help in reducing the pressure further.  This is medical management of glaucoma or using eye drops to lower the pressure.
 
If the pressure does not reduce to the target level with glaucoma eye drops your doctor may suggest you to get a glaucoma filtering surgery.  This is also known as trabedulectomy.
 
There is also another option that your dotor may consider if the pressure does not drop to the desired levels.  If you also have a cataract, even if the cataract is not very advanced, your doctor may consider performing a cataract surgery.  Usually after cataract surgery the pressure reduces by a bit and this may help in reaching the eye pressure target.  You can read more about cataract surgery.
 

Frequently Asked Questions

Yag PI costs you Rs 4000 per eye.   After the procedure you have to use certain eye drops for a week.  You may feel a small prick in the eye but its not really painful.
 
There is a 30% chance that the opening that we have created closes on its own and thus there may be a need to redo the opening.  If needed the second time in less than 2 months then the cost would be Rs 2000 per eye.

You may feel a slight pain at the time of laser.  One could compare it to a mosquito bite.  It is bareable and usually is not an issue.

It takes 2-5 minutes per eye to perform Laser.

As we apply anaesthetic drops before doing it there is no pain. Occasionally a mild stinging sensation may be experienced.

A drop is prescribed to reduce the inflammation in the eye. The patient is required to come the next day to get the eye pressure checked and also to check the laser opening made in the eye.

The procedure is done in the OPD itself not in the ot. So it is very convenient for the patient.

As it is a very small opening that too at the periphery of the eye it cannot bee seen. Also it is done in the upper half so it gets covered by the upper eyelid. 

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