YAG Posterior Capsulotomy:
At the time of cataract surgery the cataractous lens is completely removed from the eye and its thin outer capsule is left behind. It is within this capsule that the intraocular lens is placed. At first the capsule is clear and does not impede clear vision. Over time however, the capsule can become translucent due to scarring factors elicited by the body. This can diminish the visual benefits of the original surgery. This process is sometimes called a “secondary cataract.” This term is erroneous and is a misnomer. The cataract once removed CANNOT return. Rather, “capsular opacification” is a much better description of term. The Nd:YAG laser, quickly and efficiently opens an area in line with the patients pupil in the capsule. The remaining capsule is unharmed thus not interfering with the lenses stability or position in the eye. Vision is restored to previous levels as the cloudy capsule is removed from the visual line of sight. Better still, once removed it is extremely rare for the membrane or capsule to regrow over the visual axis. YAG capsulotomy as it is termed is therefore most often literally a “one shot deal.”
The procedure to open the capsule takes less than 2 minutes and is painless. A contact lens is placed on the surface of the eye after the eye is anesthetized with drops. The cold laser light is then used to open the capsule by the ophthalmologist. Vision returns quickly afterwards once the dilating and anesthetic drops wear off. The most common side effect is a few additional “floaters” or spots in the field of vision but they are usually very minimal. The biggest risk is retinal tear or detachment with the procedure but this is seen in far less than 1% of cases.
If you have had cataract surgery this is just one more reason to see your optometrist yearly so that he or she can monitor your ocular health including looking for signs of capsular opacification that may require this procedure.
YAG Peripheral Iridotomy:
This procedure places a microscopic hole or apertures in the iris (coloured part) of the eye. The apertures are placed under the lid so that vision is unaffected and is only visible with microscopic eye examination. This procedure is used to re-route the aqueous or internal eye fluid in eyes at risk for narrow angle glaucoma. Many eyes are congenitally at risk for this problem due to their shape or overall small size. As we get older the lens in our eye grows and takes up more space. This can close off gradually or acutely resulting in chronic or acute angle closure glaucoma. To treat this condition, the Nd:YAG iridotomy gives an alternate route for internal eye fluid and can effectively open and keep open the internal drain in patients pre-disposed to angle closure.
As part of a routine ocular examination, your eye doctor will determine if you are at risk for progressive angle closure and may recommend you be considered for this procedure. Done preventively, this can reduce the risk for the often devastating ocular effects of “acute angle closure glaucoma”. In this condition the eye pressure suddenly rises as the internal drain is completely closed off. The iridotomy as well as medical therapy then becomes a matter of emergency. Vision losses, pain, nausea, vomiting all accompany this serious eye condition. The iridotomy is then performed but often not before irreversible sight loss occurs from the nerve damage caused by the extreme eye pressure inherent by the attack. Thus, as part of a routine ocular health exam, those patients at risk can be identified and the procedure done preventively.
There is no long term risk to the procedure. Minor microscopic bleeding at the time can occur. In addition the preparatory eye drops given before can cause a mild frontal headache in some patients. Rarely patients can experience some visual aberration in some lighting conditions from the opening but this is very rare, and in a predisposed patient is a small price to pay in order to prevent angle closure attacks.
Selective Laser Trabeculoplasty (SLT):
The SLT laser is used a means to lower pressure in those eyes with “open angle glaucoma”. The laser is used to deliver energy to the drainage system at the front of the eye between the iris and peripheral cornea. It is painless and only a small contact lens is placed on the eye during the procedure. Between 50 and 90 bursts of laser light are applied over 2-3 minutes. The laser does not create scarring, holes or any other visible effects on the drain of the eye. Rather, the laser elicits an immune response much like your skin might do after sun exposure. This has the effect of making the drainage system (trabecular meshwork) more efficient. More fluid is allowed to leave the eye and the eye pressure (IOP) is lowered. Often 20-30% IOP lowering can be achieved with this procedure. It is often used as a 2nd or 3rd line choice IN ADDITION to eye drops to lower pressure further beyond what the medication can provide. For some patients it can be offered as a 1st line choice and is more effective in some types of glaucomas versus others.
The beneficial effects of the laser take up to 90 days to occur. Thus, you will be seen in the office after 3 months to recheck your eye pressure. Mild inflammation, eye redness, foreign body sensation and photophobia can occur for a few days afterwards. The preparatory eye drops given before the procedure can give a mild frontal headache for a few hours in some patients.
Feel free to inquire about this procedure if you have been diagnosed and are being treated for glaucoma or elevated eye pressure.
More information can also be found at www.opthalmic.lumenis.com