Glaucoma is a complex anterior segment eye disease which most commonly causes damage to the optic nerves, blind spots, and loss of vision when fluid called aqueous humor builds up in the front (anterior segment) of the eye and causes increased intraocular pressure (IOP), which is transmitted to the optic nerve. It affects millions of people worldwide and is the second leading cause of blindness. Dr. Shin manages glaucoma medically but refers patients requiring laser or surgical intervention of glaucoma to fellowship-trained glaucoma specialists.
MOST COMMON TYPES OF GLAUCOMA
- Primary Open-Angle Glaucoma (POAG) is the most common type of glaucoma and results from increased intraocular pressure caused by inadequate drainage of the aqueous fluid from the eye. Since there is rarely pain associated with this type of glaucoma, most people do not notice any change in their vision until the damage is quite severe.
- Closed- or Narrow-Angle Glaucoma (ACG) is less common and occurs when the peripheral iris is too close to and ultimately blocks the drainage angle, which prevents fluid in the eye from reaching the drainage canal and egressing from the eye. When complete blockage of the drainage angle occurs over a short time, intraocular pressure rapidly rises and is referred to an acute angle-closure attack. Symptoms of an acute angle-closure attack include severe eye pain, sudden onset of blurry vision, headaches, nausea, vomiting, or visual disturbances such as rainbows or halos around lights. Acute angle closure can cause blindness if not treated immediately. Patients with this type of glaucoma should vigilantly avoid taking over-the-counter medications with warnings that they may trigger acute angle closure. Angle closure can evolve slowly, and then patients may not appreciate symptoms until optic nerve and visual field damage are advanced.
- Low or Normal Tension Glaucoma (LTG) results in optic nerve damage and vision loss despite consistently low or normal intraocular pressures (less than 21mmHg). Even with single-digit IOP readings, approximately 15% of patients still progress possibly due to low blood pressure at night, low ocular perfusion pressure, low intracranial pressure, and/or sleep apnea.
- Glaucoma Suspect is a term used for patients with one or more risk factors/clinical indications of glaucoma, such as increased intraocular pressure (ocular hypertension), which may lead to glaucoma but do not definitively demonstrate optic nerve damage or vision loss due to glaucoma.
GLAUCOMA RISK FACTORS
Glaucoma can be inherited or result from congenital eye malformations, eye trauma, inflammation, or develop secondarily to certain systemic condition such as rheumatoid arthritis. Other risk factors include:
- age over 40
- family members with glaucoma
- African and Hispanic (POAG)/ Japanese, American Indian, and Alaskan (LTG)/ Chinese, Pakistani, and Vietnamese (ACG)
- high eye pressure
- myopia or hyperopia
- have corneas that are thin in the center
- have thinning of the optic nerve
- have diabetes, migraines, poor blood circulation or other health problems affecting the whole body
Glaucoma is most often treated with prescription eye drops which lower intraocular pressure either by reducing the amount of aqueous humor produced or by facilitating the drainage of the fluid drain. There are many different eye drops for glaucoma and sometimes more than one eye drop is needed to adequately control intraocular pressure. Combination eye drops, which combine two different classes of glaucoma medications, are available. The drops must be instilled daily, sometimes more than once per day, and many have side effects including redness, irritation, dry mouth, eyelash growth, blurry vision, altered breathing, and changes in pulse, heartbeat, or energy level. Some eye drops can interfere with systemic medications, so it is important to provide a list of your current medications to Dr. Shin. New drug delivery systems, such as a combination of a traditional glaucoma drug with nitric oxide to more effectively lower pressure in the eye and continuous therapeutic delivery devices (punctual plug, vitamin E- or nanodiamond-embedded contact lenses, soft ring with glaucoma medication on the eye under the highest and lowest part of the eyelids, and intraocular slow-release device) to rid the patient of daily eye drops are being developed.
Depending on the type and severity of your glaucoma, a laser trabeculoplasty [(argon laser trabeculoplasty (ALT) and selective laser trabeculoplasty (SLT)] or laser iridotomy may be recommended. While the treatment mechanisms are different, both of these procedures facilitate better aqueous fluid drainage through the drainage canal and can be performed in the office or at an outpatient surgical center.
If conservative treatments have not been successful or other personal circumstances warrant more aggressive treatment, a trabeculectomy (filtration surgery) or implantation of a glaucoma drainage (tube shunt) device, both of which are performed from the outside the eye, have traditionally been considered. Since 2004 upon FDA approval of the Trabectome, but more predominantly since 2012 with the FDA approval and advent of the iStent, minimally invasive/micro-invasive/microincisional (MIGS) procedures, which use an inside-the-eye approach, have been added to the surgical options for glaucoma patients. In general, MIGS procedures are safer, less invasive, and shorter but produce more modest results than traditional glaucoma surgery.