Alamo Optometry Blog

March 11, 2013

Broken Blood Vessel

Filed under: Uncategorized — gkblog @ 9:00 pm

(As appeared in Alamo Today, March 2013)         

When patients call into the office with a concern of a broken blood vessel (subconjunctival hemorrhage) in the eye, they are usually pretty scared about what is happening to their eye.  In a very high percentage of times, this is a completely benign condition; it just looks a lot worse than it actually is.

            For patients who have never had this happen to them before, it can be a scary situation to see your eye extremely red.  We have found that patients generally think the worst when something goes wrong with their eyes and/or vision.  As I tell everyone, thankfully most of the time the condition is treatable and will not lead to permanent vision loss.  However, that is not the case all the time; therefore a visit to the eye doctor is prudent to come up with the correct diagnosis and treatment plan.

            A subconjunctival hemorrhage occurs when a very small blood vessel (capillary) bursts within the layers of the front part of the eye.  This bleeding will usually obscure the eye so you can’t see through to the white part of the eye and it can happen anywhere on the surface of the eye.  These small bleeds generally get larger after the initial incident because the outside layer of the eye has a cellophane look and feel to it; this tends to push down and spread out the blood.  I will tell patients that the eye will look a little worse in the initial 24-48 hours before the blood starts to get reabsorbed.  With a hemorrhage of this kind, the patient should have no other symptoms besides the red eye.  There should be no pain, discomfort, vision loss, or discharge.  Patients often do not even notice it until they look in the mirror or are asked by someone else, “What is wrong with your eye?”  It is at this point that a call is then made for an office visit. 

            The most common cause of this condition is “it just happens.”  Most of the time, a patient will go to bed fine and wake up with the hemorrhage.  Other typical causes are trauma to the eye, heavy lifting, coughing, high blood pressure, and secondary to some medications.  I have found that blood pressure is usually not the cause as it would require extremely high blood pressure to have an effect.  Some medications including aspirin, prescription blood thinners, and some OTC medications such as ginkgo biloba in some people can cause the blood to thin too much and be a reason for the hemorrhage.  However, these medications are usually prescribed for a heart condition and some blood disorders and are therefore necessary for the health of the patient.  I will always instruct the patient to not change their current medications, but that it might lengthen the time for full recovery. 

            Once the diagnosis is made, there is no treatment necessary.  The blood will reabsorb within 1-2 weeks depending on the size of the initial hemorrhage.  As the blood breaks down on the surface of the eye, it might start to change colors, similar to a “black and blue bruise”.  If the cause of the hemorrhage was a foreign body to the eye, then I will prescribe a mild antibiotic to cover against an infection.  Cool compresses will not hasten recovery, but I would avoid warm compresses as heat dilates your blood vessels, thus bringing more blood to the area.  I find most patients just need to understand what happened and reassurance that it is nothing to worry about and that it is not contagious.  Even though this condition is completely benign, it can be confused with other issues that require treatment.  You should have your eyes checked at the office to ensure that the eyes are healthy and that there is no need for treatment or referral.

Visual Fields

Filed under: Uncategorized — gkblog @ 8:59 pm

(As appeared in Alamo Today, February 2013)         

Since we now have a new automated visual field machine in the office, I thought it would be a good time to discuss this important topic.  I think most if not all patients have had their visual fields tested when they have visited the optometrist.  Most patients just assume it is something done during the visit, but few are probably aware of the many indications to assess visual fields and what possible visual field deficits can tell about your eyes and overall health.

            To understand visual fields, we must first discuss how peripheral vision is created and processed by the brain.  It is important to note that each area of the retina corresponds to the opposite area in the visual field, i.e. the superior area of the retina corresponds to your inferior visual field, and the temporal retina (area closer to your ears) corresponds to the nasal visual field.   The photoreceptors throughout the retina all send their signals to one area in the back part of the eye that comes together and then exits the retina as the optic nerve.  Part of each optic nerve crosses to the other side of the brain at a place called the optic chiasm located very close to the pituitary gland.  Then these fibers travel through different parts of the brain until they reach the occipital lobe, which is in the back of the head.  By knowing the type and location of the peripheral vision defect, your optometrist can have a good idea where the potential issue is.  For example, a pituitary gland tumor will cause a temporal field loss in both eyes.  Since the nerve fibers of the nasal optic nerve cross over by the pituitary gland, those fibers are therefore damaged and will cause a visual field deficit. 

            As a visual field defect can occur anywhere along the optic nerve trail, a condition of the optic nerve itself will cause a specific kind of field loss.  As most people are aware, the location of your optic nerve is your blind spot because there are no photoreceptors on the nerve itself, just the fibers from the photoreceptors.  Therefore an enlarged blind spot will show up when there is an infection, inflammation, or trauma of the nerve; the area immediately surrounding the nerve head will be swollen and therefore will not function properly.  Most types of optic nerve diseases will also show specific patterns of field loss like glaucoma.  Glaucoma is one of the more well-known diseases that are monitored by visual fields.  Since glaucoma slowly kills the optic nerve, there will be a corresponding field loss associated with the dead and dying section of the nerve.

            One of the other main reasons to assess visual fields is to make sure there are no effects on the macula from certain medications.  Early detection can very often help to prevent vision loss.  It is common that visual field loss will precede actual vision loss, so it is not sufficient to follow these patients by routine vision assessment alone.  Some common medications that warrant this are tamoxifen (for breast cancer), and plaquenil (a drug commonly used to treat some autoimmune diseases such as lupus).  There are certain types of visual tests that should be done on these patients to monitor them.  Communication with the prescribing doctor is also paramount to inform him/her of any visual effects so any modifications in their treatment plan can be made. 

            Unfortunately, doing this test does require a patient to have relatively good vision.  So for conditions such as advanced macular degeneration or other conditions with severe vision loss, a visual field assessment is not very useful because the patient does not have the acuity necessary to do the test.  A visual field test is a valuable tool in assessing the eyes, visual system, and the body as a whole as certain medications and diseases such as diabetes and hypertension can cause conditions in the eye and brain that would show up in an eye exam and/or a visual field test.

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