The 2008 CITT study published in the Archives of Ophthalmology clearly supports the superiority of office-based vision therapy to home-based vision therapy alone for convergence insufficiency. As noted in the AOA’s Clinical Practice Guideline (CPG) on Care of the Patient with Accommodative and Vergence Dysfunction home-based vision therapy may be less effective than in-office therapy because no therapist is available to correct inappropriate procedures or to motivate the patient. The preferred clinical management therefore consists of in-office vision therapy supplemented with home therapy.
The AOA CPG on this subject presents three general phases of vision therapy:
- Normalizing accommodative and vergence amplitudes. Most clinicians use large targets in which convergence and divergence demand is slowly changed. The patient is encouraged to exert maximum effort to increase his or her vergence amplitudes, and accommodative facility exercises are performed concurrently.
Sample procedures include loose lens accommodative rock, monocular near-far Hart Charts, Brock String, and Vectograms.
- Increasing the speed of response to accommodative and vergence stimuli. During this phase, it is beneficial to use targets that gradually become smaller and to use different stimuli to obtain generalization. After the amplitudes reach normal levels, the patient is encouraged to repeat the
task enough times to make the response become automatic and effortless. Once monocular accommodative facility has improved, binocular accommodative facility procedures can be performed. Suppression controls may be needed with the binocular accommodative techniques. In general, the power of the binocular accommodative flippers is increased until the patient can successfully clear +/-2.50 D, and vergence ranges are increased until the patient meets performance criteria such as PFV break of >30^ with recovery no less than 15^, without compromising normal NFV ranges.
Sample procedures include detailed vectograms, computerized binocular stimuli, stereoscope, and aperture rule.
- The third phase of vision therapy uses jump or step vergence stimuli. Instead of responding to incrementally increasing stimuli, the patient is required to make large-jump accommodative and vergence movements. Accommodation and vergence are integrated through techniques that stimulate accommodation while holding vergence stable and vice versa. This final phase of vision therapy is designed to automate both accommodative and vergence reflexes, and to enhance the flexibility between accommodation and vergence. The goal of vision therapy is to re-establish automated, effortless accommodative and vergence responses under any stimulus condition. Improvement of ranges alone is not sufficient. The patient should now be able to meet the criteria for passing the Convergence Insufficiency Symptom Survey (CISS) on the printable card above.
Sample procedures include loose prism jumps, eccentric circles and life savers.