Understanding Ptosis and the Superior 36 Visual Field Test

Ptosis is a relatively common condition, although the exact prevalence is not known. When surgical correction is indicated, understanding ptosis and the Superior 36 Visual Field Test can help provide needed documentation. This article briefly explains what ptosis is, the different types of ptosis, the ptosis visual field-testing process, and how newer technologies using the Virtual Field headset can help with management.

What is Ptosis?

Ptosis, or blepharoptosis, is a drooping of the upper eyelid or eyelids when looking straight ahead. This condition often causes a loss of the ability to see a standard visual field; it can indicate a more serious underlying condition or, more commonly, can be related to aging. Ptosis is sometimes considered a cosmetic issue, but even mild cases can cause some visual field loss. The condition can also worsen over time, depending on the cause. 

Types of Ptosis

Ptosis can be present since birth or acquired, affecting one eye or both. The acquired form is more common and caused by various underlying conditions. Here is a list of the different types of acquired ptosis:

1. Aponeurotic ptosis is the stretching or thinning of the tendon of the levator muscle, the muscle responsible for lifting the upper eyelid. This type is the most common form of acquired ptosis.
2. Myogenic ptosis is related to weakness of the levator muscle, caused by conditions such as myasthenia gravis or ocular myopathy.
3. Neurogenic ptosis is related to nerves that control the eye. It is not as common but can be more serious. Examples include third nerve palsy, Horner syndrome, stroke-related symptoms, and multiple sclerosis.
4. Mechanical ptosis is caused by a mass, swelling, or another process that alters the eyelid's position. A common example is the ptosis induced by a heavy brow.  Chalazia (styes) and orbital tumors are other examples.  
5. Traumatic ptosis results from injury to the eye socket that damages the structures of the tendons and nerves that operate eyelid movement.
6. Pseudoptosis occurs if the edge of the eyelid is in the correct position, but the skin is overhanging to such an extent that it creates a similar visual obstruction to true ptosis. This condition may still require correction depending on the degree of visual field loss.

Why Run the Superior 36 Visual Field Test?

To demonstrate the need for surgery, a provider must show that surgical correction is necessary and that the repair will improve the client's vision. Documentation often includes the following:

1. Photographs of the patient prior to surgery to document the position of the eyelid visually
2. Ptosis visual field tests to demonstrate loss of peripheral vision
3. A description of the impact on the patient’s activities of daily living and quality of life.
4. Testing with phenylephrine, a medication that contracts the muscle, may be used to predict patient response to surgery, if internal approaches to ptosis surgery are used.

While healthcare professionals can perform several ptosis tests, the Superior 36 test is the visual field test most often required by insurers to demonstrate the necessity for surgical correction of ptosis or pseudoptosis. It is an abbreviated visual field test that demonstrates superior visual field loss in a way that is not fatiguing to most patients.  The exam is usually done twice. The first exam is completed with both eyelids taped and the second with both un-taped. Light stimuli are shown up to 52 degrees superiorly or above the eye, with a 6 decibel (dB) stimulus at each position. The stimulus is retried if it is missed the first time.

Finally, visual field testing, such as Virtual Field, can help assess the deficits caused by ptosis and establish a functional need for surgical intervention. 

Interpreting the Test Results

Ophthalmologists use visual field tests to document the degree of peripheral vision loss due to ptosis. The tests determine how well a patient can see above, below, and to either side while looking straight ahead. The results are interpreted to not only determine loss of peripheral vision,measured in dB, but also percent of visual field improvement, which is required by most insurance providers. Recommendations for surgery, medication such as the newly approved oxymetazoline 0.1% drop, or the need for further evaluation can be made in tandem with other exam findings, depending on these results.

Ptosis visual field tests can be difficult to administer due to several factors, including a patient's inability to hold their gaze on a single point, being able to push the button to indicate when the stimulus occurred, difficulty understanding direction from the technician, or variations in pupil size. Because this can lead to errors, the test may be repeated more than once in a single visit. When results are not accurate, the functional impact on the patient may not be evident.

Treatment Decisions

Once the ophthalmologist gathers the information from the Superior 36 visual field test and other field tests, they can determine the degree of vision field loss related to ptosis, as well as the potential visual field improvement surgery could provide. The ptosis visual field test results, photographic evidence, exam findings, and patient symptoms allow the provider to demonstrate medical necessity. For example, the patient must have difficulty reading, significant loss of peripheral vision, or loss of their field of vision related to seeing eyelashes or upper eyelid skin to qualify for surgery. Providers can follow these parameters over time in conditions likely to progress if the threshold for surgery is not met.

Virtual Field is a fast, easy way to administer ptosis visual field tests. The Virtual Field headset has the potential to help more patients with visual field loss without the need for bulky equipment. For more information, see Virtual Field for a free 30-day trial.

References

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