LB 15 Large Horizontal Prism Bar
plastic ophthalmic prism bars have been re-engineered to solve the problem of birefringence which can hinder their use in certain clinical applications. Our exclusive manufacturing process greatly reduces optical strain, producing prisms that virtually eliminate clinical birefringent effects.
Prism birefringence can adversely affect your vectographic testing by degrading target contrast ("image washout”), or in extreme cases, by reversing the eye that sees the target (“vectographic reversal”). Birefringence occurs in ordinary prisms because of optical strain which is due to minute molecular misalignments that occur in plastic manufacturing.
Our prism bars are made of extremely high quality plastic, which are optically clear with an index of refraction of 1.49 and a light transmission value of 92%.
The prism bars are available in various horizontal or vertical configurations, in diopter or degree ranges and sizes.
Horizontal - Calibrated in Frontal Postion