GLAUCOMA SUSPECT AND TRAUMATIC EYE INJURYOphthalmologist Carolina Valdivia, MD discusses what it means to be a glaucoma suspect and how it can relate to traumatic eye injury.  A 44 year-old man from New Jersey, USA writes:Last December I suffered a 3.5mm full-thickness laceration in my right eye, just off center of the pupil. The injury was caused by a piece of metal flying into my eye, while I was attempting to break open a padlock. I was treated by an ophthamologist and fortunately there was no loss of vision. I do not wear glasses and I never had any eye problems prior to this injury. During the course of my treatment, my intraocular pressure was a consistent 10-12. I just went for a 6-month follow-up visit and I was informed that my pressure is 22. I shared with the doctor that I was having a feeling of heaviness in my right eye and some slight blurriness. The doctor now is working me up for glaucoma and told me to schedule an appointment in 4 weeks for a visual field exam. I've been concerned about my pressure reading, as I have been feeling pressure in my right eye. I called for an earlier appointment because I'm concerned that putting off the visual field exam for 4 weeks might not be a good idea, given my elevated intraocular pressure. My question is how dangerous is this and should I be worried? Thank you for your time.
The American Academy of Ophthalmology defines a normal intraocular pressure as one that falls between 10-21 mmHg. I prefer to use the more strict range of 10-20 mmHg, as I have found that a consistent pressure of 21 mmHg still can cause optic nerve damage. Either way, the intraocular pressure reading of 22 mmHg in your right eye places you slightly outside the normal range. It is important to keep in mind that the established normal range actually is an average population statistic. A more specific definition of a normal range is one that does not cause damage to YOUR optic nerve. For example, in normal tension glaucoma, intraocular pressure readings that are within the statistically normal range still cause optic nerve damage. Additionally, an optic nerve that has experienced previous damage can be damaged further by intraocular pressures at the upper end of the normal range (17-20 mmHg).Your ophthalmologist has found high intraocular pressure in your right eye after several months of following you for a corneal injury. This places you in the category of a glaucoma suspect, meaning that you have risk factors for glaucoma (e.g. ocular hypertension ) but do not yet exhibit other evidence of the disease. Ocular hypertension is caused by a number of factors and can be transient (lasts for a short time), intermittent (comes and goes), or chronic (lasts for a long time). From your description, your ophthalmologist has not yet determined which of these three categories you fall into. Trauma to the eye often involves transient ocular hypertension, as inflammation alone can cause intraocular pressure to elevate. Usually once the inflammation is controlled, the eye pressure returns to a normal range. This apparently was not a problem in your case. However, sometimes ocular trauma can result in problems that are not immediately apparent at the time of the injury, such as deterioration of the trabecular meshwork architecture, corneal neovascularization, release of pigment granules from the iris, or uveitis. All of these can raise intraocular pressure and make you a glaucoma suspect. The fact that you have ocular hypertension should not be confused with a diagnosis of glaucoma. Some persons with ocular hypertension remain glaucoma suspects for life and never develop glaucoma. Glaucoma involves irreversible damage to the optic nerve. The injury can be mild or severe and is diagnosed by visualization of the optic nerve, the use of diagnostic imaging such as optical coherence tomography, the detection of abnormalities in optic nerve function determined through a visual field examination, and in most cases the presence of elevated intraocular pressure.From your description, examination of your optic nerve either has shown no evidence of damage or produced inconclusive results. This is good news for you. Even if you are in the process of developing glaucoma in your right eye, it has been caught early and steps can be taken to control progression of the disease. Alternatively, if there is no optic nerve damage at this time, then you will be followed as a glaucoma suspect. However, ophthalmologists never rely on just one line of evidence. For this reason, your doctor has arranged for you to undergo a visual field examination, which can revel deterioration of the visual field due to glaucoma-related damage before it is detectable through a visual examination of the optic nerve. Depending on the results of the visual field examination, other tests may be required as well. I have had several patients with intraocular pressures that fall between 18-22 mmHg. Some of are in the process of observation and diagnosis of glaucoma, while others I am following as glaucoma suspects. My decision to initiate treatment depends on several factors. Among these are a family history of glaucoma, trauma to the eye (as in your case), the patient's race/ethnicity, and the presence of anatomical abnormalities in the eyes. Your doctor is following the standard protocol recommended by the American Academy of Ophthalmology for glaucoma suspects. It is important that she or he is able to determine if you have existing optic nerve damage. Even if there is no evidence of damage at this time, it is equally important to obtain baseline measurements against which future tests can be compared to determine if there is a progression to glaucoma. This is what your visual field examination will help to accomplish. Given that you are a glaucoma suspect, the four-week waiting period should not be a problem. Carolina Valdivia, MD
REFERENCE:Warren KS and Contractor M. Glaucoma Suspects. In: Zimmerman TJ and Kooner KS. Clinical Pathways in Glaucoma. New York: Thieme, 2001:57-70.
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