Glaucoma is typically characterized as a group of optic neuropathies which develop optic nerve damage secondary to varying levels of intraocular pressure (IOP).
If untreated, glaucoma can lead to permanent vision loss. The visual loss can start with unnoticeable edges of the field of vision and progress to tunnel vision, and in some cases, blindness. It is estimated that as many as 2.2 million Americans have glaucoma, and a similar number may have the disease without knowing it.
5 Most Common Types of Glaucoma:
Primary Open Angle: In open-angle glaucoma, the drain of the eye is normal in configuration, but becomes impermeable over time, causing an increase in intraocular pressure (IOP) and subsequent damage to the optic nerve. It is the most common type of glaucoma. Most people have no symptoms and no early warning signs. If open-angle glaucoma is not diagnosed and treated, it can cause a gradual loss of vision. This type of glaucoma typically develops slowly and sometimes without noticeable loss of sight. It often responds well to medication, if caught early and properly treated.
Angle Closure: This type of glaucoma is also known as acute glaucoma or narrow angle glaucoma. It is much rarer and is very different from open-angle glaucoma in that the eye pressure usually rises very quickly. This happens when the drainage canals get blocked acutely. Symptoms of angle-closure glaucoma may include headaches, eye pain, nausea, rainbows around lights at night, and very blurred vision.
Low-Tension or Normal-Tension: With this type of glaucoma, damage occurs to the optic nerve without eye pressure exceeding the normal range. In general, a “normal” pressure range is less than 20 mm Hg. The causes of LTG are still unknown. For some reason, the optic nerve is susceptible to damage from eye pressure, which for most people is in the normal range. Approximately 10-15% of all glaucoma are of the low-pressure variety.
Secondary Glaucoma: This type refers to cases in which another ocular or systemic disease causes or contributes to increased eye pressure, resulting in optic nerve damage and vision loss. Secondary glaucoma can occur as the result of an eye injury, inflammation, tumor, or in advanced cases of cataract or diabetes. It can also be caused by certain drugs such as steroids. This form of glaucoma may be mild or severe.
Glaucoma Suspect: This describes a person with one or more risk factors that may ultimately lead to glaucoma, but this individual does not have definite optic nerve damage or visual field loss. The goal of identifying and treating patients who are glaucoma suspects is to preserve visual function by monitoring them for the earliest signs of damage.
During an exam, in addition to checking your eye pressure, your eye doctor may use drops to dilate the pupil to examine your optic nerve. Your doctor may also use diagnostic machines such as OCT (Ocular Coherence Tomography), HRT (Heidelberg Retinal Tomography), Pachymetry, and Stereo Disc Photographs to visualize, assess, and archive damage to the optic nerve. This can sometimes show damage in eyes before it is suspected by the doctor’s examination.
If damage is severe enough, vision changes can be detected on a peripheral vision test known as a Visual Field Test. Often the patient won’t notice peripheral vision changes until there is significant vision loss. Once the glaucoma diagnosis is made either by optic nerve examination or visual field testing, treatment is initiated.
Treatment of Glaucoma
Depending on the type of glaucoma you have, different treatment options may be considered. Treatment options include topical (prescription eye drops), laser therapy, and conventional glaucoma surgery. Many cases of glaucoma can be controlled with one or more drops, but some people may require surgery to reduce their IOP further to a safe level by improving the outflow or drainage of fluids. Occasionally, surgery can eliminate the need for glaucoma eye drops.
Laser Procedures and Surgery
An in-office laser treatment may be used to treat glaucoma. An iridotomy is a laser procedure used to treat narrow/closed angle glaucoma. Another type of laser treatment, trabeculoplasty, is used to treat open angle glaucoma, especially when drops are unsuccessful. Types of laser trabeculoplasty include Argon Laser Trabeculoplasty (ALT) and Selective Laser Trabeculoplasty (SLT). During a trabeculoplasty, a laser is directed into the trabecular meshwork, the drain of your eye. The effect of this laser treatment develops over several weeks, and can last up to several years. When its effectiveness lessens, it can often be repeated.
Micro Invasive Glaucoma Surgeries (MIGS)
ABiC: Ab Interno Canaloplasty (ABiC), a minimally invasive glaucoma surgery that can effectively reduce the elevated eye pressure associated with glaucoma. ABiC is based on the same principles as angioplasty, a procedure that opens blocked arteries and restores normal blood flow to your heart muscle. It uses breakthrough micro catheter technology to enlarge your eye’s natural drainage system, improving outflow and lowering eye pressure. With this single-handed instrument, your surgeon is able to lower the intraocular pressure of the eye by surgically opening the eye’s natural drainage system without permanently implanting a device within the conjunctiva or sclera. The surgery begins by accessing the area using a single self-sealing, clear corneal incision, an ab-interno approach. A cannula is inserted through the incision that contains a microcatheter which can be advanced 360 degrees around the eye. Your surgeon is able to deliver controlled amounts of viscoelastic fluid directly into Schlemm’s canal, where the drainage takes place, as the microcatheter is retracted. This jelly-like fluid will stretch and widen the canal which is designed to increase the outflow of fluid from the eye, thereby lowering the pressure of the eye. This can be done as a stand-alone procedure or combined with cataract surgery.
Trabeculectomy 360: With this single-handed instrument, your surgeon is able to lower the intraocular pressure of the eye by surgically opening the eye’s natural drainage system without permanently implanting a device within the conjunctiva or sclera. The surgery begins by accessing the area using a single self-sealing, clear corneal incision. A cannula is inserted through the incision that contains a microcatheter which can be advanced 360 degrees around the eye. The drain of the eye is manually opened while retracting the microcatheter. By doing so, the surgeon removes any blockage which allows a smooth output of the fluid directly through the canal. This lowers the buildup of fluid causing excessive pressure within the eye. This can be done as a stand-alone procedure or combined with cataract surgery.
iStent Trabecular Micro-Bypass: A newer surgical therapy for glaucoma that is designed to improve aqueous outflow to safely lower IOP may reduce the need for glaucoma eye drops – this is at the discretion of the doctor. iStent is the smallest medical device ever approved by the FDA. It is placed in the eye during cataract surgery. iStent is so small that a patient isn’t able to see it or feel it after surgery, but it will work continuously to help reduce eye pressure.
XEN®45 Gel Stent: Dr. Nairn was one of the first surgeons in Pennsylvania to perform this innovative glaucoma implant. The XEN® Glaucoma Treatment System is designed to reduce intraocular pressure in eyes suffering from refractory glaucoma, including cases where previous surgical treatment has failed, cases of primary open-angle glaucoma, and pseudoexfoliative or pigmentary glaucoma with open angles that are unresponsive to maximum tolerated medical therapy. The device creates a permanent channel through the sclera allowing flow of aqueous humor from the anterior chamber (AC) into the subconjunctival space. Clinical trials support the efficiency of the Xen® Gel Stent in those patients who have failed prior in multiple surgical procedures.
Kahook Dual Blade: This device allows the surgeon to reduce intraocular pressure (IOP) by removing a section of trabecular meshwork and the inner wall of Schlemm’s canal. The Kahook Dual Blade procedure is quick and painless, requiring no sutures and providing rapid postoperative visual recovery. The Kahook Dual Blade procedure can be performed as a standalone procedure, or in combination with cataract surgery. Topical medications are normally used to manage postoperative recovery.
Endoscopic Cyclophotocoagulation (ECP)
A laser procedure that is often performed at the same time as cataract surgery for patients who suffer from both cataracts and glaucoma. Recent studies show that patients who undergo the combined ECP/cataract surgery need fewer glaucoma medications over the long term.
Trabeculectomy (filtration surgery)
Performed to reduce eye pressure in patients with open-angle glaucoma, trabeculectomy is usually done when other treatments for glaucoma have failed to adequately lower eye pressure. The goal of this surgery is to lower eye pressure to prevent further loss of vision from glaucoma. During trabeculectomy surgery, a new drainage passage is created to filter fluid from the eye. This new opening allows the fluid inside the eye to drain out of the eye, bypassing the trabecular meshwork, the clogged drainage passages present in people with glaucoma.
Ex-PRESS® Mini Shunt
A type of trabeculectomy in which the fluid in your eye is diverted through an extremely small tube to the outside of the eye. Although the device is as small as a grain of rice, it acts just like a heart stent keeping a pathway open so blood (or fluid) can successfully go around the blockage. The Ex-PRESS provides precise control of the amount of fluid that is allowed to flow out helping the eye maintain a healthy level of internal pressure.
Seton Tubes or Glaucoma Tube Shunts
These devices that are implanted in the eye to provide an artificial alternative drainage site for fluid to exit the eye. These devices lower eye pressure. A tiny tube extends from the body of the device into the anterior chamber, which is the front part of the eye that usually drains fluid from the eye. The device allows excess fluid to drain out through the tube and be absorbed in surrounding tissues. These implants fall into two categories: non-valved (free flow implants; i.e. Baerveldt) and valved (resisted-flow implants; i.e. Ahmed)