Optometrists are able to address the visual needs of stroke survivors, an underserved population.
When it comes to optometric care, stroke survivors are often an under-served population-especially when most of them have visual or ocular deficits. Stroke survivors with visual problems are often dead-ended in neuro-ophthalmology offices because the internists and cardiologists who refer them to neuro-ophthalmology don’t know that ODs can treat stroke-related visual/ocular challenges. Plus, many optometrists are unfamiliar with how they can help stroke survivors.
Although a background in behavioral optometry, vision therapy, and/or neuro-optometric rehabilitation is helpful, primary-care ODs can easily learn the basics necessary to treat the most common visual problems of those who have had a stroke.
Almost 800,000 people suffer a stroke every year, and it is the most common disability among American adults.1 A stroke occurs when there is an interruption of the blood flow to an area of the brain. There are two types of strokes: an ischemic stroke, occurring when a blood clot blocks a blood vessel, and a hemorrhagic stroke, occurring when a blood vessel in the brain ruptures and causes damage. Some strokes are preceded by brief episodes of stroke symptoms known as transient ischemic attacks (TIA), which are temporary interruptions of blood supply to the brain.
Because a TIA can occur hours, days, or weeks before a full stroke, it behooves us to be aware of the symptoms and signs-temporary episodes of weakness, numbness, paralysis of the face, arm or leg (especially on one side of the body), difficulty speaking or understanding simple statements, and loss of balance or coordination.2 These symptoms can occur on only one side of the body. To that list should be added any report of even momentary diplopia, transient loss of visual field, or a passing episode of blurry vision.
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Every primary-care optometrist can-and should-as a minimum perform the following work-up on a patient presenting with any signs:
• History of stroke-related signs and symptoms
• Best-corrected visual acuity
• Pupil reflexes
• Cover test, phorias, ocular range of motion
• Threshold visual field testing
• Dilated fundus examination
• Stethoscope auscultation of the carotid arteries for bruits
Whether a clinical ocular deficit is discovered, any transient visual episode should trigger a call to the patient’s internist or cardiologist to urge the physician to schedule the patient for a physical. In addition, I proactively write the patient an Rx for carotid Doppler testing and/or a CT scan-this starts the ball rolling.
When a patient presents with a known, previously documented stroke, pay attention to current complaints of persisting hemianopsia, diplopia, or eyelid dysfunction. These conditions can often be treated by the primary-care optometrist.
Diplopia from a recent stroke is confusing to the patient because adaptation by a head turn or suppression has not yet occurred. Diplopia also causes symptoms of dizziness, poor balance, trouble reading, psychological stress, asthenopia, and headaches. Patients with double vision may mention those complaints but not say “double vision” unless asked.
Most stroke survivor with a known cerebrovascular accident (CVA)-related diplopia has been instructed to patch the deviating eye. This makes the patient happy because the patch resolves the diplopia. Unfortunately, patching the deviating eye for too many weeks can embed the binocular dysfunction, reducing the possibility of gaining binocular vision.
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Therefore, as a minimum, ensure that the eye patch is alternated daily from the right eye to left eye. To keep the schedule simple, I tell patients to patch the right eye on even-numbered calendar days and to patch the left eye on odd-numbered calendar days.
Keep in mind that when patching to compensate for diplopia, the patient may be annoyed or uncomfortable because of the reduced peripheral vision caused by the patch. In those cases, selective occlusion can be used by cutting a piece of Transpore surgical tape into a small rectangle to block central vision in front of the pupil of the deviating eye. The tape blocks double vision and allows the patient to retain an awareness of periphery in the occluded eye, which feels more comfortable and is safer than a traditional eye patch.
Some patients with obvious large angles of paretic strabismus do not complain of diplopia. That is because the angle of strabismus is so large that the patient can concentrate on the image straight ahead of the non-strabismic eye while ignoring (but not necessarily suppressing) the diplopic image located way off center. Although patients may not complain of diplopia, they may still have behavioral symptoms of confusion, poor balance, or poor ambulation due to visual confusion induced by the ambient diplopic image. This problem requires consultation with an OD skilled in treating binocular vision dysfunction.
Stroke-related binocular dysfunctions with mild-to-moderate paretic angles of strabismus often are capable of gaining a wider range of motion of the effected eye. This can be achieved by having the patient monocularly track a moving target (pursuits) in the direction of the restrictions several times per day for a few weeks.
Many patients are told by non-optometric doctors that double vision may resolve on its own within a vague timeline of months without mentioning vision therapy or prism. It is dismaying that people with stroke-related hemiplegia are recommended to have physical and occupational therapy, but patients with diplopia are given only an eye patch and not afforded a chance for binocular rehabilitation. I suggest prescribing prism glasses as a stopgap measure to help the patient feel more comfortable.
Simple vision therapy procedures using a Brock string or red-green tranaglyphs may help until vision therapy is initiated. Never prescribe a ground prism into glasses until a two- to three-month trial with a Fresnel prism has shown the angle of deviation to be steady and that the double vision has been resolved.
It is important to prescribe the total amount of Fresnel prism with the prismatic compensation broken up between the two eyes to allow the Fresnel-induced reduction in contrast to be distributed evenly between both eyes.
For example, if an esotropia-related diplopia is resolved with 20 D base-out prism, it may seem simple to prescribe a single 20 D base-out Fresnel prism before the deviating eye. However, the patient will usually complain of blur in the eye with the Fresnel prism. Two 10 D base-out prisms are a better choice because they equalize the 20 D Fresnel-induced poor contrast, which reduces patient complaints.
Furthermore, splitting the prism power between two eyes allows the freedom to fine tune the prism power when, or if, the patient’s angle of deviation changes. Peel off one of the Fresnel prisms and replace it with another power as is clinically indicated. Keep in mind that the angle of the paresis measured when viewing at distance may be very different than at near, so separate prismatic distance glasses and reading glasses are often required.
When prescribing compensating prism for vertical diplopias, remember that the angle of deviation usually varies depending on head position. Be sure to prescribe the vertical prism with the patient’s head in a straight-ahead position and warn the patient that a chin-up or chin-down head position will likely cause him to see double in spite of the prism.
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A patient whose diplopia is resolved with prism may begin to complain again of diplopia in a few months. Never assume that a renewed complaint of diplopia implies a worsening of the condition. It may mean that the strabismic angle is decreasing.
Do not be disheartened if a rare patient can’t fuse binocularly with any amount of prism. A prism bar may seem to neutralize the diplopia while the patient is in the chair, but you may find that when you prescribe Fresnel prisms, the patient still complains of double vision. At times despite re-measuring, fine tuning, and changing prism power, the patient continues to not fuse the diplopic images.
Some neuro-related diplopias are difficult to resolve because of damage in the brain pathways responsible for the binocular vision reflex, and horror fusionalis, when it occurs, is difficult or impossible to resolve-an alternating eye patch may be the only treatment available.
Stroke-related hemianopsia is reasonably common. The field defect is obvious on a 24-2 threshold visual field test.
However, some stroke survivors have hemi-spatial inattention (also known as “neglect”), which is an inattention to or lack of sensory awareness of visual space to one side. It may or may not be associated with a hemianopsia.
Patients with hemi-spatial inattention will usually be unaware of their inability to perceive space on the affected side, may not be able to follow a moving target in the direction of the neglect, and may say that their physician or occupational therapist “said” that they have visual concerns to the side (although the patient is not cognitively aware of the hemianopic like loss of visual field). That is a difficult concern to address and should be referred to an optometrist skilled in neuro-optometric rehabilitation.
Hemianopsia usually leaves a person disoriented and struggling to make it through daily living. People with hemianopsia are often afraid to leave their homes and are concerned about their safety. They are confused in a busy visual environment-such as the mall where they may bump into people-or have the fear of falling off a curb.
Hemianopsia can cause a sense of loss of independence due to discontinuing driving. Others find that ambulatory activities are more difficult. People with hemianopsia (but without hemi-spatial inattention) can often be helped by an optometrist.
As a minimum, recommend two separate pairs of glasses: one for distance and one for near. Separate pairs are needed because with hemianopsia, bifocals or progressive lenses limit the width of the seeing area through the glasses. In my experience, hemianopsia patients usually have fewer field-related complaints with full-field single-vision glasses.
I have designed and prescribed specially-designed eyeglasses over the past 20 years to help those with hemianopsia. The optical care of hemianopsia is based on using prism to expand side vision awareness. Available hemianopsia-related glasses I worked with were difficult to prescribe, difficult for the patient to use, or had optical design flaws.
I learned what worked and what didn’t work. I designed a prism technology called SVAG (Side Vision Awareness Glasses) that can be prescribed by any trained optometrist (See Figures 1 and 2).
Prior to developing SVAG, hemianopsia-related eyeglasses afforded only a limited circular viewing area. This limited the patients’ appreciation of the expanded field awareness or required a highly-cognitive patient who could adjust to simultaneously viewing straight ahead while noticing out-of-focus peripheral images caused by Fresnel prism.
I developed SVAG with a high Abbe value because patients with older hemianopsia glasses complained of distracting color aberrations. SVAG also have a higher index of refraction, making them thinner and more cosmetically acceptable. There is also no prism button or Fresnel lens strip on the front of the lens. SVAG provides clear side vision with a wide viewing area when looking through the prism lens.
Some stroke patients develop blepharoparesis, while others develop ptosis.
If there is ptosis, avoid disuse of the ptotic eye by taping it open about a centimeter for five minutes a few times per day using Transpore surgical tape. Be sure to allow enough slack in the tape for blinking. Patients should instill an artificial tear every minute to prevent discomfort and drying during the interval the eye is taped open.
If there is a blepharoparesis and the eye won’t close, be sure to use Transpore surgical tape to keep the eye closed to prevent corneal staining and discomfort.
After years of watching physical therapists work use massage with stroke patients, I decided to try a similar massage technique on the eyelids. I found that some patients with stroke-related ptosis or blepharoparesis responded to an eyelid massage.
The massage is conducted with your finger, using a brisk moderate stroking of the affected lid in a lateral and radial fan shape. An alternating warm or cool pack applied before lid massages may increase sensory stimulation to the lids, enhancing the effect. Massage for a few minutes four times per day for three weeks. Discontinue if no change in ptosis or belpharoparesis.
Some ptosis patients have what I call diplopic pseudo-ptosis or DPP. Stroke survivors with a stroke-related esotropia or exotropia subconsciously learn to close the offending eye to avoid diplopia. Although they will appear to have ptosis, it is not ptosis. Cover the non-ptotic eye; if the patient is capable of opening the apparently ptotic eye, you have discovered a DPP.
For blepharoparesis, I sometimes use commercially available lid weights to pull the lid down. The lid weights come in a fitting set of graded weights with an adhesive backing. These test weights are used to determine the weight of a gold lid implant used by oculoplastic surgeons. Optometrists can use the test set weights to treat blepharoparesis noninvasively until surgery is indicated.
Specialty optometric consultation is available through colleagues associated with Neuro-Optometric Rehabilitation Association (NORA) and the College of Optometrists in Vision Development (COVD).
1. National Stroke Association. What is stroke? Available at http://www.stroke.org/understand-stroke/what-stroke. Accessed 3/22/16.
2. National Stroke Association. Transient Ischemic Attack. 1999. Print.