a. overview of retinal laser treatment

b. overview of laser treatment for glaucoma and narrow angles

c. overview of laser treatment for posterior capsule opacity

d. preparing for laser treatment

The retina is a thin, light-sensitive tissue layer at the back of the eye. A healthy retina is critical for normal, clear vision. Light rays are focused onto the retina through our cornea, pupil and lens. The retina converts the light rays into impulses that travel to the brain via the optic nerve. The brain then translates these messages into the images that we see.

Retinal holes or tears typically occur when the vitreous gel that fills the eye pulls on the retina. This can occur with aging or after eye surgery, and people may notice floaters or flashing lights in their vision. Some people are predisposed to retinal holes and tears because they are very myopic (nearsighted) or have areas of thinning in the peripheral retina. Retinal tears and holes can lead to retinal detachment, which can subsequently cause blindness if not treated in a timely manner.

Laser treatment, specifically called “Barrier Laser” or “Laser Retinopexy”, is recommended to seal or “spot-weld” the area around the tear or hole before it develops into a retinal detachment. The laser treatment does not have any effect on floaters or flashes. Sometimes, if the areas of thinning or tears are very extensive, multiple sessions of laser may be required.

Macular edema occurs when damaged blood vessels in the retina allow fluid to escape into the retinal tissue and cause it to swell. The macula is the very center of the retina and is responsible for central vision and color vision. A frequent cause of macular edema is diabetes, although it can also occur in uveitis, retinal vein occlusion, and other diseases.

Laser treatment may be recommended to decrease the amount of macular swelling, which may help to stabilize and hopefully improve central vision. This type of laser, referred to as “Focal retinal laser”, is typically not painful and can be completed within several minutes. Multiple sessions may be required, which may be a few months apart.

Blood vessels in the eye can become damaged in many diseases. Commonly, it can occur in diabetes, retinal vein occlusions, retinal vasculitis, sickle cell disease, and other conditions. When blood vessels in the back of the eye become damaged, this prevents oxygen and nutrients from getting to the retina. This is called “ischemia”. The retina tries to fix this problem by growing new blood vessels. Unfortunately, these new blood vessels are abnormal and grow like weeds onto the surface of the retina. They do not help to bring oxygen or nutrients, but instead they bleed into the eye and pull on the retina.

When there is retinal ischemia, laser treatment called “Pan-retinal Photocoagulation” can significantly reduce the chance of new abnormal blood vessels growing and help other abnormal vessels to regress or shrink. This can prevent further vision loss, and in some cases, help patients to regain vision. Retinal ischemia is a serious condition, and without treatment, there is a significant chance of permanent blindness. Typically, this type of laser requires multiple sessions before treatment is complete.

The laser treatments are usually done with local anaesthetic or numbing eye drops. The pupils are also dilated with drops. Sometimes, an anesthetic injection is given just under the surface of the eye for additional pain prevention.

A lens is then placed on the surface of the eye to focus the laser, and the patient is asked to position their chin and head at the laser machine. This looks similar to the slit lamp examination machine that is used to look at the eye, except that a laser is attached. Most patients find the laser light to be very bright. It is very important to keep one’s eye still and not move during laser treatment, so the laser can treat only the intended area. This minimizes any risk of vision loss as a result of laser. The laser session typically takes 5-10 minutes and is usually associated with mild discomfort.

Afterwards, the vision may feel very dark for a few minutes, and then will slowly recover over the next 5 minutes. Patients may be given artificial tear drops to help with any irritation they feel afterwards. There is no restriction on activity after laser treatment, and people usually feel back to their baseline by next day or two.

Laser treatment is generally, but not always successful. It is possible that the eye disease is too severe, and vision can continue to worsen despite laser, or further treatments may be required. There is a 1-2% risk of developing scar tissue or wrinkling on the central retina after laser treatment, which can cause distortion or require surgery to fix. Extensive laser treatments referred to as “Pan-retinal photocoagulation” or PRP, which are typically used in patients with abnormal retinal blood vessels, can cause a decrease in night or peripheral vision, or swelling in the macula. Very rarely, laser treatment can cause permanent pupil dilation and glare. If a patient moves during the laser procedure, they may notice a permanent dark spot in their central or peripheral vision.

Glaucoma is a condition that can cause vision loss when the intraocular pressure (IOP) damages the optic nerve. Open angle glaucoma is the most common type of glaucoma and can be treated with Selective Laser Trabeculoplasty (SLT) – a medical office procedure that helps to lower intraocular pressure (IOP).

During the laser treatment, short pulses of low-energy light are delivered to the cells of the structure in your eye that is responsible for pressure balance (the melanocytes in the trabecular meshwork). The cells in these structures heal and rebuild, and as they rebuild, the intraocular pressure is lowered. The light is targeted so it does not affect other structures in your eyes. This laser is 90% successful in lowering the IOP and lasts for 2-3 years on average. It is safe to repeat the laser.

Narrow angles is a risk for angle-closure glaucoma, which can occur suddenly (acute angle closure glaucoma) and more gradually (chronic angle-closure glaucoma). Both acute and chronic angle closure can lead to high pressure in the eye and vision loss due to damage to the optic nerve (glaucoma).

Some people have narrow angles but no glaucoma. In in this situation, the iris is very close to the drainage angle in their eye, or the angle between the iris and the cornea is narrow. Although there may not be any damage to the nerve, (no glaucoma), having a narrow angle is a risk for angle closure glaucoma. The risk of developing glaucoma if you have a narrow angle is 10%.

Laser peripheral iridotomy is performed to create an alternative outflow pathway for the aqueous fluid in the eye. This is a medical procedure during which the laser creates a small hole in the iris, which allows aqueous (fluid at the front of the eye) to travel directly from where it is produced (beside the lens) to the anterior chamber and then the outflow angle This alternative pathway for aqueous fluid is prevents or can treat “pupillary block” in eyes with narrow angle or angle-closure glaucoma.

Selective Laser Trabeculoplasty (SLT) is 90% successful in lowering the IOP and lasts for 2-3 years on average. It is safe to repeat the laser. The risks of the procedure include inflammation, raised pressure in the eye, and cornea swelling which are rare and usually temporary. IOP is checked 30 minutes following the SLT procedure in order to ensure that the IOP is not elevated and to provide treatment if required.

Laser peripheral iridotomy is a safe and very successful procedure. In some cases, the laser peripheral iridotomy has to be repeated. Many patients will experience mild blurred vision and discomfort for 1-2 hours after the procedure. In 1-2% of cases, a transient rise in the intraocular pressure (IOP) above 21 mmHg (normal IOP is <= 21 mmHg). This is treated with drops and rarely, oral medications. The IOP is checked 1 hour after laser peripheral iridotomy in all patients in order to detect this IOP rise and treat if required. Sometimes a small bleed can occur beside the laser hole. The ophthalmologist may apply some light pressure to the eye if this is seen at the time of the laser. This minor bleed resolves by itself. We do not recommend stopping aspirin or other blood thinners before or after the laser procedure. Rarely patients can experience transient glare, halos, line,s spots and shadows after laser peripheral iridotomy. These visual symptoms are uncommon and usually resolve by 6 months.

If you experience problems after your laser, please contact your ophthalmologist.

During cataract surgery, your ophthalmologist removes the cataract (cloudy lens) ad places an acrylic intraocular lens (IOL) on the posterior capsule or thin membrane that used to envelop the natural lens. In <5% patients who have had cataract surgery, this posterior capsule can become cloudy or opacified (posterior capsule opacity) and may cause the vision to be blurred or hazy. Posterior capsulotomy is a laser procedure that makes a small opening in the cloudy posterior capsule opacity and clear the vision again. Posterior capsulotomy is preformed 4 months or longer after cataract surgery.

Laser posterior capsulotomy is safe and usually does not result in any complications. Risks are low but include retinal hole or tear, retinal detachment, mild inflammation in your eye, shift in the intraocular lens (IOL) (very rare) and minor rise in intraocular pressure.

Your ophthalmologist will carefully examine the IOL position, intraocular pressure peripheral retina 1 month after laser capsulotomy to ensure that no retinal holes, tears, detachments have occurred and that your IOL is in position.

If you experience flashes, floaters, decreased vision or a curtain in your peripheral vision after laser capsulotomy, please contact your ophthalmologist for an eye check sooner than your scheduled 1-month appointment.

Laser treatments are performed in the office or in the hospital.

No preparation is necessary at home. Please continue to use any drops prescribed by your ophthalmologist.

If you are booked for a laser treatment at St. Joseph’s Health Centre, you will be given an appointment day and time for the laser treatment at the eye clinic. Please bring your health card to the appointment.

When you arrive at the hospital a nurse will place drops into your eye. Once the drops have worked, the nurse or ophthalmologist will place freezing or numbing drops into your eye and your ophthalmologist will perform the laser treatment.

If you had a laser peripheral iridotomy performed, you will be asked to wait one hour for an intraocular pressure (IOP) measurement.

A follow-up appointment will be booked to check your eye 1 month after the laser treatment.

If you are booked for a laser treatment at the office, please arrive on the day of the appointment with your health card.

When you arrive at the office, an ophthalmic technician will place dilating drops into your eye. Once the eye is dilated, your ophthalmologist will freeze or numb your eye with drops and sometimes with a small injection just under the surface of your eye. Your ophthalmologist will then perform the laser treatment.

You will be able to go home shortly after the laser treatment.

A follow-up appointment will be booked to check your eye 1-2 months after the laser treatment.