How to Care For Stroke Patient at Optometrist Level

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When it comes to optometrist 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.

Stroke basics

A stroke most common disability among adults. 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. 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.

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

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, neurasthenia, 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.



 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.

Using prism

Many patients are told by non-optometrist doctors that double vision may resolve on its own within a vague timeline of months without mentioning vision therapy or prism or prism bar. 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.

Fresnel prism
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.

Prism Bar Therapy
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.

These are the basic care given by ODs and many more therapy are give by the during Stroke By ODs to maintain there Binocular vision.


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