Glaucoma is a chronic eye condition that causes gradual vision loss due to irreversible damage of optic nerve, which is caused by increased intraocular pressure. The treatment of glaucoma; be it eye drops, laser or incisional surgery aim at lowering intraocular pressure to prevent/slow optic nerve damage.
Generally, the first line of treatment for glaucoma is medications followed by laser and other surgical procedures if glaucoma is not controlled with conservative treatment. Surgery involves laser or incisional surgery and usually laser surgery is recommended prior to incisional surgery. In laser, a focused light beam is used to release intraocular pressure by treating trabecular meshwork. Various laser surgeries used to treat glaucoma are selective laser trabeculoplasty (SLT), argon laser trabeculoplasty (ALT), laser peripheral iridotomy (LPI) and laser cyclophotocoagulation.
Laser trabeculoplasty is usually performed in patients with open angle glaucoma when eye drops and medications fail to reduce the intraocular pressure. There are basically two types of laser trabeculoplasty that include argon laser trabeculoplasty (ALT) and selective laser trabeculoplasty (SLT).
- Argon Laser Trabeculoplasty (ALT): The laser beams help in opening the drainage system releasing the pressure inside the eye. In general, only half of the fluid channels are treated in the first session and if necessary then other half can be treated in the second session.
- Selective Laser Trabeculoplasty (SLT): It is usually attempted after an unsuccessful attempt with ALT. In SLT low-level laser is used to target only selective areas of the trabecular meshwork with increased pressure, therefore it can be repeated several times without causing any scarring at the angle.
- Laser Peripheral Iridotomy (LPI): This is mostly used for angle closure glaucoma, which occurs when the angle between the iris (colored portion) and cornea (clear outer layer) becomes narrow. LPI is used to relieve pressure by creating a small hole in the iris, thus leading to normal fluid drainage.
Laser Cyclophotocoagulation: This laser treatment is usually reserved for severe glaucoma patients who have severe vision loss. It is used to destroy ciliary bodies that produce aqueous humor, which will lead to decreased intraocular pressure.
In incisional surgery (filtering surgery), an artificial drainage hole is created in sclera with procedures such as trabeculectomy or sclerostomy to release intraocular pressure. Aqueous shunt devices, which are used as artificial drainage devices are also becoming popular at reducing intraocular pressure. The examples of shunts used are Ahmed shunts (valved) or Baerveldt shunts (non-valved). There are also newer procedures known as minimally invasive glaucoma surgery (MIGS) that hold promise at treating glaucoma. These include Trabectome, iStent and CyPass Micro-Stent.
Trabeculectomy involves partial removal of clogged trabecular meshwork with the help of incisions to release the intraocular pressure (IOP). Hence, a new drainage pathway for aqueous humor is created and this fluid collects under the upper conjunctiva in a bleb entering capillary blood circulation, thus lowering the intraocular pressure.
Trabeculectomy is performed when other treatment options such as medications, eye drops or laser surgery are not effective at lowering intraocular pressure. The surgery aims at decreasing intraocular pressure in open angle glaucoma by opening trabecular meshwork. In closed angle glaucoma, the intraocular pressure is reduced by creating small holes in the iris.
How Long Does It Take To Recover From Glaucoma Surgery?
The recovery of a glaucoma patient from laser is quick and the patient can resume his daily activity immediately the next day after laser treatment, but doctor advises to avoid eye straining, heavy lifting, bending for a few weeks as a precautionary measure for both laser and conventional surgery. Glaucoma symptoms are relieved within a few days after laser surgery with minimal post-surgical symptoms of mild irritation, redness and tearing.
The recovery time in incisional surgery is usually longer extending from 2 to 4 weeks and it may even take up to 2 months for vision to stabilize. The rare side effects of glaucoma surgery include loss of vision, infection, sensitivity to light, long term irritation of the eye, bleeding, low eye pressure, scarring, cataract and/or need for more surgery.
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