2018 Prisms
5 likes746 views
The document discusses the principles and applications of prisms in pediatric ophthalmology, focusing on prism diopter measurements and factors affecting them. It covers various types of prisms, methods for measuring and inserting them into spectacles, and tests for assessing eye misalignment. Additionally, it provides a skills checklist for differentiating between glass and plastic prisms and executing specific cover tests.
2018 Prisms
- 3. Factors Affecting Measurement • Prism placement: – plastic prisms: frontal plane – glass prisms: prentice position • Stacking prisms • Splitting prisms From Rosenbaum & Santiago, Clinical Strabismus Management
- 4. Glass Prisms • One face perpendicular to light rays • Back face parallel to iris • Prisms in spectacles • Measure back surface of spectacles flat against nose cone of lensmeter
- 6. Inserting Prisms in Glasses • 1D lens, decentered 1 cm = 1 PD • Effectively only about 4 cm/4PD can be done by displacing center (beyond 5 cm already beyond edge) • Grind in beyond 4PD each lens(?)
- 10. Cover Tests and Endpoints • Cover Uncover Test • Simultaneous prism cover test • Prism under cover test • Alternate prism cover tests • Phorias, fixation preference • Monofixation • DVD • Gold standard for any misalignment
- 11. Skills Checklist • Differentiate between glass and plastic prisms • Prentice vs Frontal plane • Direction of prisms for ET, XT, HT/HoT • Stacking prisms • Splitting prisms • True vertical vs DVD • End point of prism testing • Neutralizing combined deviations: – XT w HoT in 3rd nerve – ET with DVD – XT with HT