Strabismus & Prism
Horizontal Prism Value Lookup
Combined prism power when one horizontal prism is held over each eye.
Combined Prism Power
Prism 1 + Prism 2Choose the two prisms that are being held in front of each eye.
Prism 1 (prism diopters)
Prism 2 (prism diopters)
Resultant Prism Power
—Δ
- One prism held over each eye
- Prisms are assumed to be in the opposite directions over each eye (e.g. both base in or base out)
- Prisms are in the frontal plane position
Adapted From: Thompson & Guyton. Ophthalmic Prisms: Measurement Errors and How to Minimize Them. Ophthalmology 1983;90:204-2010