Eye discomfort, eye fatigue, blurred vision at near, headaches, or diplopia. Most common in young adults but may be seen in older people. Symptoms are usually associated with periods of prolonged near work.

Critical

An exophoria at near in the presence of poor near-fusional convergence amplitudes, a low accommodative convergence/accommodation (AC/A) ratio, and a remote near point of convergence.

• Uncorrected refractive error: Hyperopia or over-minused myopia.

• Accommodative insufficiency (AI): Often in prepresbyopia age range from uncorrected low hyperopia or over-minused myopia. While reading, a 4-diopter base-in prism placed in front of the eye blurs the print in AI but improves clarity in convergence insufficiency (CI). Rarely, adolescents may develop transient paresis of accommodation, requiring reading glasses or bifocals. This idiopathic condition resolves in several years.

• Convergence paralysis: Acute onset of exotropia and diplopia on near fixation only; normal adduction and accommodation. Usually results from a lesion in the corpora quadrigemina or the third cranial nerve nucleus and may be associated with Parinaud syndrome. 

NOTE A diagnosis of convergence paralysis should prompt neuroimaging to rule out an intracranial lesion.

• Primary or idiopathic CI.

• Fatigue or illness.

• Drugs (parasympatholytics).

• Uveitis.

• Glasses inducing a base-out prism effect.

• Postviral encephalitis.

• Traumatic brain injury.

• Parkinson disease.

1. Manifest (without cycloplegia) refraction.

2. Determine the near point of convergence: Ask patient to focus on an accommodative target (e.g., a pencil eraser) and to state when double vision develops as you bring the target toward them. In general, a normal near point of convergence is <8 cm. A near point of convergence exceeding 6 cm from the bridge of the nose in prepresbyopic patients or 10 cm in presbyopic patients is regarded as increased and abnormal.

3. Check for exodeviations or esodeviations at distance and near using the cover tests (see Appendix 3, Cover/Uncover and Alternate Cover Tests) or the Maddox rod test.

4. Measure the patient’s fusional ability at near. Have patient focus on an accommodative target at their reading distance. With a prism bar, slowly increase the amount of base-out prism in front of one eye until patient notes double vision (the breakpoint), and then slowly reduce the amount of base-out prism until a single image is again noted (the recovery point). A low breakpoint (10 to 15 prism diopters) or a low recovery point or both are consistent with CI.

5. Place a 4-diopter base-in prism in front of one eye while patient is reading. Determine whether the print becomes clearer or more blurred to rule out AI.

6. Perform cycloplegic refraction after the previous tests.

NOTE These tests are performed with the patient’s spectacle correction in place (if glasses are worn for near work).

1. Correct any refractive error. Slightly undercorrect hyperopia and fully correct myopia.

2. Encourage good lighting and relaxation time between periods of close work.

3. Near-point exercises (e.g., pencil push-ups): The patient focuses on a pencil eraser while slowly moving it from arm’s length toward the face. Concentrate on maintaining one image of the eraser, repeating the maneuver when diplopia manifests. Try to bring the pencil in closer each time while maintaining single vision. Repeat the exercise 15 times, five times per day.

4. Near-point exercises with base-out prisms (for patients whose near point of convergence is satisfactory or for those who have mastered pencil push-ups without a prism): The patient performs pencil push-ups as described previously, while holding a 6-diopter base-out prism in front of one eye.

5. For older patients, or those whose condition shows no improvement despite near-point exercises, reading glasses with base-in prism can be useful.

6. Consider referral to an orthoptist for vision therapy (including computer-based orthoptic programs), which has been shown to be more effective in reducing symptoms and signs of CI in children than pencil push-ups.

7. Surgery may be necessary for severe cases of CI. Indications for surgery include exotropia present more than half the time, declining exotropia control with reduced stereoacuity and increased exodeviation size, rapid loss of exotropia control in younger patients, and persistent double vision.

8. Botulinum toxin has shown potential as a therapy for patients who have not benefited from previous nonsurgical or surgical treatments.

Nonurgent. Patients are reexamined in 1 month.