Laser therapy in Glaucoma
There are several forms of laser therapy for glaucoma.
1. Laser iridotomy (LI or PI) involves making a hole in the colored part of the eye (iris) to allow fluid to drain normally in eyes with narrow or closed angles.
2. Argon laser trabeculoplasty and selective laser trabeculoplasty (SLT) are quick, relatively painless, and safe laser procedures for lowering the intraocular pressure in open angle glaucoma. Microscopic laser burns to the angle allow fluid to better exit the drainage channels.
3.Laser cyclo-ablation (cyclophotocoagulation or CPC) is another form of laser treatment generally reserved for patients with severe forms of glaucoma with poor visual potential. This procedure involves applying laser burns to ciliary body and destroying the cells that make the fluid, thereby reducing the eye pressure.
Trabeculectomy
Trabeculectomy is the most commonly performed glaucoma surgery. If successful, it is the most effective means of lowering the eye pressure. This surgery creates a tiny drainage channel, connects the anterior chamber of the eye to subconjunctival area, (the delicate membrane covering the eyeball known as the conjunctiva), forms a small reservoir called a bleb on the surface of your eye, which is hidden under your upper eyelid. The new drainage channel allows fluid to leave the eye, enter the bleb, and then pass into the capillary blood circulation (thereby lowering the eye pressure). Locally-applied medications or injections may be used to help keep the hole open.
Non-penetrating Glaucoma surgeries
The goal of nonpenetrating filtering procedures is to reduce intraocular pressure safely by enhancing the natural aqueous outflow channels without bleb or shunt.
These procedures include Canaloplasty, viscocanalostomy and deep sclerectomy. Working in the canal space provides moderate IOP control while avoiding many of the complications of traditional filtration surgery.
Shunt procedure
Aqueous shunt devices (such as Ahmed Glaucoma valve or AGV) are artificial drainage devices used to lower the eye pressure. They’re composed of a plate(reservoir) and an attached silicon tube. The reservoir is placed outside of the eye under the conjunctiva, usually underneath the upper eyelid. The tube portion of the device is carefully inserted into the front chamber of the eye, typically just in front of the iris (colored part of the eye) to create a new pathway for fluid to exit the eye through the tube, collects around the reservoir and reabsorbed.
One cannot feel the implant and it is usually not visible unless one lifts the eyelid or opens the eye very widely. The operation usually takes 45-60 mins.
Congenital Glaucoma surgeries
The main treatment options for congenital Glaucoma are surgical and include goniotomy and trabeculotomy. Surgical planning begins with a comprehensive examination under anesthesia. As long as the cornea is clear, either procedure may be performed.
In goniotomy, an incision is made across the trabecular meshwork under direct gonioscopic visualization. In trabeculotomy, the trabecular meshwork is incised by way of an external approach through Schlemm’s canal. If the cornea is hazy or opaque, trabeculotomy is the better choice.
If IOP control is not achieved with the first surgery, at least one other angle surgery is attempted before trying another strategy. When angle surgery fails and medical therapy is inadequate, other options may be considered, such as tube implant procedures, trabeculectomy and cryoablation.
