Ads
related to: base vs out prisms glasses- Take Our Color Blind Test
Discover If You Have A Red-Green
Color Deficiency With Our Test!
- About Our Company
Our Technology Is Recognized
Worldwide & Worn By Millions!
- Our Most Popular Pair
Stylish Glasses For Strong To
Severe Red-Green Color Blindness!
- Have Vision Insurance?
Get Pilestone Glasses For Free With
Vision Insurance In The US!
- Witness The Gift Of Color
Browse Through Our Pilestone Video
Reactions And Testimonials Online!
- Shop Color Blind Glasses
Find The Right Style & Type For
Your Color Blind Deficiency!
- Take Our Color Blind Test
Search results
Results from the WOW.Com Content Network
The base is the thickest part of the lens and is opposite from the apex. Light will be bent towards the base and the image will be shifted towards the apex. In an eyeglass prescription, the base is typically specified as up, down, in, or out, but left and right are also used sometimes.
The Four Prism Dioptre Reflex Test (also known as the 4 PRT, or 4 Prism Dioptre Base-out Test) is an objective, non-dissociative test used to prove the alignment of both eyes (i.e. the presence of binocular single vision) by assessing motor fusion.
An optical prism is a transparent optical element with flat, polished surfaces that are designed to refract light. At least one surface must be angled — elements with two parallel surfaces are not prisms. The most familiar type of optical prism is the triangular prism, which has a triangular base and rectangular sides.
When measuring horizontal fusion ranges, base in prisms assess fusional divergence while base out prisms assess fusional convergence. The vertical fusional vergence amplitude can also be measured with base up and base down prisms although the horizontal PFR is typically the main focus when testing.
Prism and Base Prism refers to a displacement of the image through the lens, often used to treat strabismus and other binocular vision disorders. The prism value is measured in prism diopters, and Base refers to the direction of displacement. PL is an abbreviation for plano or plain, meaning no prescription
Crown glasses such as BK7 have a relatively small dispersion (and can be used roughly between 330 and 2500 nm), while flint glasses have a much stronger dispersion for visible light and hence are more suitable for use as dispersive prisms, but their absorption sets on already around 390 nm.