Glaucoma

Glaucoma is a condition when the pressure inside the eye is sufficiently elevated to result in visual loss.  Glaucoma is very common; it is the second leading cause of blindness in the United States, with over one million Americans unaware that they have this progressive condition.  Glaucoma screening is an important part of a comprehensive eye examination.

Medical Background

The most common instrument used for measuring eye pressure is an applanation tonometer.  The tonometer is mounted on a slit lamp and pressure of the eye is safely tested after the application of anesthetic eyedrops.  Normal eye pressure is generally considered to be less than 21 mm Hg.  However, patients may develop glaucoma even with so-called “normal” pressure readings.  Findings besides pressure that indicate the presence of glaucoma include pathologic changes in the optic nerve, thinning of the retinal nerve fiber layer, and specific patterns of visual field loss.  Optic nerve photography, optical coherence topography, and visual field testing by perimetry are instruments used to detect and manage patients with glaucoma.

Treatment of Glaucoma

Treatment of glaucoma can be in the form of medication that lower eye pressure, laser surgery that opens microscopic pores that allows enhanced drainage of fluid inside the eye, or conventional surgery that facilitates the release of fluid from within the eye to exit outside the eye.

More than ten types of eyedrops are currently available for the treatment of glaucoma.  In addition, there are several types of oral medications that may be used to treat elevated eye pressure.  Each type of medication has potential complications that must be weighed against the benefits for use in a specific patient. Patients with glaucoma often use more than one type of medication at a time.

Laser surgery for glaucoma is usually non-invasive and consists of either SLT (selective laser trabeculoplasty) or ALT (argon laser trabeculoplasty).  These laser procedures are usually well tolerated and are administered as outpatient procedures. The limitation of these procedures is that they are not permanent and often need to be repeated, and that the amount of pressure reduction is unpredictable and typically modest.

Conventional surgery consists of procedures that permit the safe exit of fluid from within the eye to the outside of the eye.  Trabeculectomy, a well-established surgical procedure, involves the removal of a microscopic portion of the eye.  This creates a channel for fluid inside the eye to escape into a bubble-like space in the outside of the eye.  In many patients the bubble-like space or channel scars down and closes over time, negating the effect of surgery.  Various types of valves, most notably the Ahmed valve, provide a tube extension that drains fluid from within the eye into a chamber located outside the eye.  Drainage valves can be very effective and may function trouble-free for many years.

Legal Issues in Glaucoma

Glaucoma claims for glaucoma usually assert failure or delay of proper diagnosis, failure of proper treatment, failure of informed consent when prescribing medication that can induce glaucoma, and failure to properly monitor for progression of disease. Since glaucoma can result in permanent and significant loss of vision, the level of damages may be appreciable.

Elevated eye pressure

The diagnosis of glaucoma is based on elevated pressure sufficient to cause corresponding damage.  May patient fit into a category referred to as “pre-glaucoma” or “glaucoma suspect” when they may have elevated eye pressure or have a family history of glaucoma and not suffer damage and visual loss.  Under these circumstances it is not uncommon for an ophthalmologist to discuss suspicious findings, such as elevated intraocular pressures, and communicate elevated risk for glaucoma to the patient as required by the doctrine of informed consent.  An ophthalmologist may defer treatment for patients with pre-glaucoma because of questionable necessity or because the potential for adverse reaction to medication outweighs the benefit of treatment.

Iatrogenic induction of glaucoma

Certain medications, even when properly used, can cause elevated eye pressure and glaucoma.  Most notable among these medications are steroids either taken orally, as a nasal inhaler, or as eyedrops.  Package inserts for these medications commonly caution patients of steroid side effects, but a physician may reinforce this information on discussion with the patient and advise the patient to have periodic monitoring for glaucoma when taking steroids for a prolonged period of time.

Monitoring

Proper monitoring on a regular basis is often needed for patients who are predisposed to glaucoma or who already have glaucoma.  Early diagnosis and adjustments to treatment are needed to help prevent visual loss.  The frequency of monitoring is influenced by factors that include level of control, patient compliance, and stability of vision.

Managing glaucoma requires keen vigilance and state-of-the art technology

  • Optical Coherence Tomography: Measurements of optic nerve and retinal for accurate diagnosis and treatment.
  • Perimetry: Visual field analysis for monitoring and assessing peripheral vision.
  • Pachymetry: Measurement of corneal thickness.

Cases in Point

Dr. Reynard was retained as an expert to determine causation and damages in a patient who developed glaucoma following a foreign body injury to the eye.

Dr. Reynard was retained as an expert to assess standard of care for a patient who suffered loss of vision while undergoing treatment for glaucoma.

Dr. Reynard was the first ophthalmologist to use special glaucoma valves at St. John’s Hospital and Health Center to reduce elevated intraocular pressure.

Copyright © 2011, OcularExpert

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