Selective Laser Trabeculoplasty

The inside of the eye is filled with a clear fluid called aqueous humor. The fluid drains out through a tissue called the trabecular meshwork, sitting in the angle between the iris and the cornea. In open-angle glaucoma, the trabecular meshwork does not drain as well as it should, so eye pressure climbs and slowly damages the optic nerve ⁴.

Selective laser trabeculoplasty uses a low-energy, frequency-doubled Nd:YAG laser. The laser pulses are absorbed mainly by pigmented cells in the trabecular meshwork without burning the tissue. This selective laser action triggers a biological response that helps the meshwork drain fluid better and lowers eye pressure ³.

What happens during the procedure:

• Numbing. The surgeon places numbing drops in the eye.
• Pressure-lowering drop. A drop like brimonidine or apraclonidine is often given before and after to prevent a pressure spike.
• Contact lens. A small, mirrored contact lens is placed on the eye so the surgeon can see the drainage angle.
• Laser pulses. The surgeon delivers 50-100 short pulses around 180° or 360° of the trabecular meshwork.
• Done. The contact lens is removed. Most people see normally within a few minutes and go home with no eye patch.

Direct selective laser trabeculoplasty (Direct SLT or DSLT) is a newer way to deliver the laser through the cornea, without a contact lens. Randomized noninferiority trials of direct selective laser trabeculoplasty in open-angle glaucoma and ocular hypertension show similar pressure lowering to standard SLT ⁵.

Good signs you may be a candidate for SLT:

• You have primary open-angle glaucoma or ocular hypertension.
• You also have pseudoexfoliation or pigmentary glaucoma — both respond well, sometimes better than primary open-angle glaucoma.
• You have an open drainage angle on gonioscopy.
• You are not yet on drops and want to skip or delay them as a first treatment.
• You are on drops but find them hard to take regularly, expensive, or irritating.
• You are interested in cutting down on daily drops over the long term.

Reasons SLT may not be right:

• Angle-closure glaucoma — the laser needs an open angle to work safely. SLT is generally not the first choice here, although carefully selected primary angle-closure cases have been studied ⁶.
• Neovascular, uveitic, or post-traumatic glaucoma with a scarred angle.
• Active eye inflammation or infection.
• Severe corneal scarring or opacity that blocks the surgeon's view of the drainage angle.
• Advanced glaucoma with very low target pressure — SLT alone may not be enough.
• People who cannot sit still at the laser for 5-10 minutes.

Selective laser trabeculoplasty is one of the safest glaucoma treatments. Most side effects are mild and short-lived ⁷:

• Temporary pressure spike in the first hours after the laser, in about 5% of patients. Usually treated with a drop and a same-day pressure check.
• Mild eye redness, irritation, or light sensitivity for a day or two.
• Mild inflammation in the front of the eye, treated with a short course of anti-inflammatory drops.
• Headache or brow ache for a few hours.
• Blurry vision from the contact lens gel for a few hours.
• No effect or short-lived effect — about 1 in 5-1 in 4 patients does not get a meaningful pressure drop, and re-treatment may be needed.
• Rare: persistent pressure rise needing more treatment.
• Rare: cystoid macular edema, peripheral anterior synechiae, or corneal changes.

Selective laser trabeculoplasty has been shown to be safe and effective in patients previously treated with prostaglandin analogs and other glaucoma drops; you do not have to stop drops before SLT ⁸.

What it costs in the U.S.:

• Selective laser trabeculoplasty is recognized as medically necessary for open-angle glaucoma and ocular hypertension. It is covered by Medicare and most U.S. health insurance plans.
• Billed charges for one eye commonly range from $700-$1,800. Medicare reimbursement is roughly $300-$500 per eye for the laser code, paid to the physician.
• Out-of-pocket cost for a covered SLT is usually a deductible plus a small co-insurance share — frequently $0-$200 per eye after insurance.
• Many practices combine eyes on the same day or close together; check whether the deductible applies once or twice.

How SLT compares with the cost of drops:

• Generic glaucoma drops cost roughly $10-$50 per bottle per month. A typical patient on 2-3 drops per day pays $100-$600 per year out of pocket — for life, in many cases.
• Brand-name drops can cost several hundred dollars per month without insurance.
• Health economics analyses tied to the LiGHT trial suggest that selective laser trabeculoplasty as a first treatment is cost-effective compared with starting drops, in part because many patients can stay off drops for years ⁹.

HSA and FSA funds can be used for SLT copays. If you are uninsured, ask the practice for cash pricing and payment plans.