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History is vital part of TVO evaluation
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Taking an extensive history is key to diagnosing and treating patients with transient visual obscurations (TVOs), according to several clinicians who spoke to Primary Care Optometry News.
“In any event where the patient states that he or she has vision loss, the most important part of the evaluation becomes the history,” Daryl F. Mann, OD, told PCON.
Dr. Mann, who is president of the SouthEast Eye Specialists in Chattanooga, Tenn., said a good history can help a clinician get a better understanding of the type of vision loss a patient may have and the length of time the problem persists.
John A. McCall Jr., OD, a PCON Editorial Board member who practices in Crockett, Texas, said it is important for clinicians to establish whether this vision loss is occurring in one eye or both.
“If it is in both eyes, it’s usually less severe, because it’s more than likely an ocular migraine, which is a vascular constriction,” Dr. McCall said in an interview. “That usually lasts 15 to 25 minutes, and then when it’s gone it’s as if nothing ever happened.”
Monocular transient vision loss, on the other hand, could point to something more sinister such as several types of optic neuropathy, optic neuritis, retinal detachment, transient ischemic attacks, stroke or brain tumor.
“The history becomes very important in determining what level of suspicion you have for something that could have a higher potential of morbidity vs. something you need not be as concerned about,” Dr. Mann added.
Questions to ask
TVOs, although sometimes harmless, can decrease a patient’s quality of life, Leonid Skorin Jr., OD, DO, FAAO, FAOCO, who practices in Albert Lea, Minn., told PCON in an interview.
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“In most instances these can be so common during the day that some patients actually become functionally blind,” he said. “It affects their ability to drive a car or get around because their vision is constantly fading in and out.”
Dr. Mann said certain points should be determined when taking the history of a patient with TVOs:
- Establishing which eye is involved and to what extent. For example, is there a loss of peripheral or central vision?
- Finding out what the patient sees during the episode.
- Determining how long the vision was obstructed.
These types of questions can help a practitioner get a better understanding of the type of vision loss a patient has and the length of time the problem has persisted, Dr. Mann advised.
Monocular disease tends to be either embolic or inflammatory. Binocular events usually point to a cortical or vascular cause.
An ischemic attack lasts for a few moments while a migraine may last more than 20 minutes. An amaurosis fugax, or a dimming of the vision that may lead to stroke, can last for several hours.
Dr. Skorin said to ask the patient if his or her sudden loss of vision is worsened by a Valsalva’s maneuver such as sneezing, coughing or straining.
“If they bend over or stand up really fast and these transient visual obscurations occur, that’s also classic for something caused by intracranial pressure,” he said.
Causes for TVOs
Dr. Skorin said a true TVO that lasts for only a few seconds may be cause for concern about possible elevated intracranial pressure.
In that case, a complete fundus examination is in order to check the optic nerve for papilledema.
“You can check the blood vessels that come out of the nerve to see if there is spontaneous venous pulsation,” Dr. Skorin said.
“Basically, depending on the mitigating factors, most of these patients are going to need an MRI scan of the brain with and without contrast dye to rule out either real tumor or pseudotumor cerebri,” he continued.
Conducting evaluations
A comprehensive eye examination is standard. Depending on the level of vision loss, a practitioner also may consider some form of visual field assessment such as a visual field test.
Dr. McCall said the 120-point visual field is standard for him on all of these types of patients. “You want to differentiate this from a true ischemic or neurologic event taking place that needs immediate intervention,” he said. “The No. 1 thing is to look at their optic nerves to see if there is any swelling of either or both. That could be a papilledema that could indicate a rise in intracranial pressure or an optic neuritis.”
Dr. McCall said he also has the patient move their eyeballs as far to each side as possible to test for pain upon excursion. Such pain, as well as afferent pupillary defect and central scotoma, may indicate optic neuritis.
If a patient has an amaurosis fugax, Dr. McCall said he orders a carotid Doppler test right away. An amaurosis fugax may be the sign of an impending stroke.
“Amaurosis fugax is a visual disturbance due to insufficient blood flow to the eye, generally coming from a blockage or stenosis of the internal carotid artery on that side,” Dr. McCall said. He added that an amaurosis fugax event might last several hours.
“That patient needs to go straight to the hospital and have a carotid Doppler done and find out if there’s some kind of an interrupted flow to the carotid artery,” he said.
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Patients might describe their vision loss as “sparkles” or “looking through cracked glass” to complete obscuration of vision, said Leo P. Semes, OD, a professor of optometry at the University of Alabama at Birmingham and PCON Editorial Board member.
“Those that I’d want to focus on would be secondary to ischemia or carotid insufficiency,” Dr. Semes told PCON in an interview. “Typically those are unilateral. They last up to 20 minutes and they may or may not be accompanied by other physical signs such as weakness, numbness and inability to move limbs.”
If the patient has a pale nerve, the first thing to consider is temporal or giant cell arteritis, which can be ruled out with an ESR, Dr. Semes said. An immediate treatment would be a course of oral steroids, he added.
Age a factor
Age plays a role in determining what kind of evaluation to proceed with, according to J. James Thimons, OD, a PCON Editorial Board member who practices in Fairfield, Conn.
“It really is an age-dependent phenomenon,” Dr. Thimons said in an interview. “In a younger patient it is unusual to have significant underlying systemic disease. Those people get looked at from more of a perspective of migraine headaches or some form of atypical migraines that might have caused the event.”
Dr. Thimons said a patient on medical therapy such as birth control pills may require a full neuroophthalmic evaluation, including possible visual fields, cranial nerve evaluations and lab testing due to the established risk of vascular occlusive disease associated with that therapy.
“With an elderly patient, you pursue a different course,” Dr. Thimons said. “There you are looking more towards cardiac function, carotid capabilities and the potential for temporal artery disease. You need to make sure carotid vessels are normal and that there wasn’t some sort of embolic event. Additionally it is important to evaluate cardiac function for conditions such as atrial fibrillation or other malfunctions of the vascular supply that can create a short-term insufficiency of perfusion to the cortex, optic nerve or associated tissue. A large part of TVOs have to do with the age of the patient.”
In this case, Dr. Thimons orders several laboratory tests and assesses the patient’s pulse for pace and irregularity and evaluates the blood pressure in the office.
“It’s actually one of the larger workups I do in an initial examination because of the potential threat of morbidity and mortality to the patient,” he said. “If there’s something to discover, you need to find it as soon as possible.”
For more information
- Daryl F. Mann, OD, is president of SouthEast Eye Specialists LLC in Chattanooga, Tenn., and a former president of the Tennessee Optometric Association. He can be reached at 1949 Gunbarrel Rd., Ste. 220, Chattanooga, TN, 37421; (423) 508-7337.
- John A. McCall Jr., OD, is a Primary Care Optometry News Editorial Board member, a private practitioner and senior vice president of vendor relations for Vision Source. He can be reached at 711 East Goliad Ave., Crockett, TX 75835; (936) 544-3763; fax: (936) 544-7894; e-mail: jmccall@visionsource.com.
- Leonid Skorin Jr., OD, DO, FAAO, FAOCO, practices in Albert Lea, Minn., and writes and lectures on ocular disease and neuro-ophthalmic disorders. He may be contacted at the Albert Lea Eye Clinic, Mayo Health System, 1206 W. Front St., Albert Lea, MN 56007; (507) 373-8214; fax: (507) 373-2819; e-mail: skorin.leonid@mayo.edu.
- Leo P. Semes, OD, is a professor of optometry, University of Alabama at Birmingham and a member of the Primary Care Optometry News Editorial Board. He may be contacted at 1716 University Blvd., Birmingham, AL 35294-0010; (205) 934-6773; fax: (205) 934-6758; e-mail: lsemes@uab.edu.
- J. James Thimons, OD, is a Primary Care Optometry News Editorial Board member. He can be reached at Ophthalmic Consultants of Connecticut, 75 Kings Highway Cutoff, Fairfield, CT 06430; (203) 257-7336; fax: (203) 330-4958; e-mail: jthimon@sbcglobal.net.
See Dr. Leo P. Semes present at PCON’s 2-credit course held during SECO 2009! Click here for details