- Measure stereopsis
- Measure fusional amplitudes with a haploscope or in free space. You can measure amplitudes in free space by introducing base in and then base out prism while asking the patient to keep an object single. You can find more details in "Binocular Vision and Ocular Motility" found on E-Resources.
- Measure near point of convergence
- Measure alignment with the cover-uncover test and the alternate cover test using an accommodative target at distance and near.
- Measure accommodative amplitude of accommodation
When you have done all of this, you will have an idea of: 1) binocular ability with stereopsis, 2) latent deviation with the cover test, and 3) ability to overcome any latent or intermittent misalignment. Then the cycloplegic refraction will tell you about the possibility of more hyperopia.
With all of this information you can go about trying to help depending on the findings. This could include near point of convergence (NPC) exercises if the NPC is remote; fusional range exercises working "against" prism if amplitudes are low (not an easy thing to accomplish); prism for an intermittent deviation, usually base in; more plus correction if refraction justifies and the patient can tolerate. Provide bifocal add if accommodative amplitudes are diminished. If there is a big intermittent XT, evaluate it carefully including after prolonged monocular occlusion and possibly, just possibly consider surgery but this is not likely.
If none of this is appropriate or treatable, advise the patient about better light, better posture, shorter periods of study and any other aspect of visual hygiene you can devise.
|Eugene M. Helveston, M.D.