A number of vision devices (particularly those for low vision) make use of high power prismatic corrections. In these situations, the standard ophthalmic prisms become too thick, heavy, and impractical. Fresnel prisms are used as alternatives, but they suffer from a number of problems, including poor optical quality. New composite prisms were designed and tested in phase I of this project. They have resulted in a significant reduction in thickness as compared to standard ophthalmic prisms. For high power prisms, their optical performance is better than equivalent refractive prisms and far better than Fresnel prisms. As a result, they could prove useful for a number of vision applications: high magnification reading spectacles, correction of diplopia, visual field remediation of hemianopic patients, diagnostics, etc.
The aim of phase II is to establish a process to produce these composite prisms in a cost effective and reproducible manner, use them to make spectacles and have them tested in extensive clinical trials by patients suffering from conditions mentioned above. Briefly put, the aim is to have these devices ready for commercialization at the conclusion of phase II.
Composite prisms have the potential to be useful for a number of vision applications where moderate to high prism powers are needed. Patients suffering from diplopia (double vision), hemianopia, strabismus, convergence insufficiency and anomalous correspondence could benefit from these devices. They may also be helpful for patients with restricted visual fields resulting from strokes or other conditions such as glaucoma and retinitis pigmentosa. Low vision patients who need high magnification reading spectacles could benefit from composite prisms as well. For such patients, composite prisms can be used to reduce eye strain and improve the chances of attaining binocular vision. They could also be useful for conditions such as torticollis and synostosis where visual image relocation may be needed.
| Katz, Milton (2004) Visual acuity through fresnel, refractive, and hybrid diffractive/refractive prisms. Optometry 75:503-8 |
| Katz, Milton (2004) Contrast sensitivity through hybrid diffractive, Fresnel, and refractive prisms. Optometry 75:509-16 |
