bubble_chart Overview

Hyperphoria is a tendency for the eye position to deviate upward. Normally, both eyes can use corrective fusion reflexes to control it, preventing the occurrence of strabismus and maintaining binocular single vision. Generally, symptoms may appear when hyperphoria exceeds 2^△. Among patients with heterophoria, hyperphoria accounts for 15–30%.

bubble_chart Etiology

1. Grade I paralysis of one or more vertical muscles is considered by White to account for 98%.

2. Higher insertion points of the medial or lateral rectus muscles in one or both eyes.

3. Anatomical abnormalities or abnormal insertions of the superior/inferior rectus or oblique muscles.

4. Other causes, such as orbital asymmetry, trauma, or intraorbital masses, are less common and show no clear correlation with refractive errors.

bubble_chart Clinical Manifestations

1～2^△hyperphoria can generally be controlled by fusion reflexes, but the vertical muscles have very little fusion reserve. Symptoms may appear when the deviation exceeds 2.5^△. Therefore, hyperphoria is more likely to cause eye muscle fatigue than esophoria or exophoria. Patients with hyperphoria experience visual fatigue both at distance and near, especially when focusing on near objects. If the degree of hyperphoria is significant, the patient may suppress the image from one eye, which over time can lead to amblyopia. If the hyperphoria is mild, the vertical diplopia is relatively close and difficult to suppress, making moderate hyperphoria more symptomatic than severe cases. Hyperphoria can cause blurred vision, headache, eye pain, and nausea. In more severe cases, stereoscopic vision may be impaired. Patients often adopt a grade I upward head tilt posture to lower the eye position below the horizontal plane, partially compensating for the hyperphoria.

bubble_chart Diagnosis

Clinical practice has proven that using a phoropter to check for hyperphoria is the best method, as even a deviation of 0.5^△ can be detected.

1. Since the rectus muscles play a larger role in distance vision, a greater degree of hyperphoria during distance viewing compared to near viewing indicates rectus muscle involvement.

2. Since the oblique muscles play a larger role in near vision, a greater degree of hyperphoria during near viewing compared to distance viewing indicates oblique muscle involvement.

3. If the degree of hyperphoria is greater when one eye is fixating compared to the other, then according to the principle that the secondary deviation is larger than the primary deviation, the fixating eye with the greater hyperphoria is the affected eye. Based on these three principles, the affected eye and muscle can be analyzed.

bubble_chart Treatment Measures

1.10^△ or less of hyperphoria can be effectively treated with base-down prism glasses. When prescribing prisms, the involvement of either the elevators or depressors should be considered. If the elevators are affected, since upward gaze is less frequent in daily activities, two-thirds of the hyperphoria measurement can be prescribed. If the depressors are involved, generally the full hyperphoria measurement should be corrected to alleviate asthenopia caused by near work.

2. For hyperphoria greater than 10^△, or if the patient cannot tolerate prism glasses, surgical treatment may be considered. Surgery is typically performed on the non-fixating eye. Preoperative analysis is necessary to determine the affected eye and involved muscles, followed by weakening the antagonist of the involved muscle, shortening the involved muscle, or weakening the yoke muscle in the contralateral eye. During surgery, weakening of the depressors should be avoided whenever possible to preserve downward gaze function.