Optical Marketplace

Unlike the oft-encountered sets made for orthoptists, this rare vintage American offering is made specifically for optoms


The idea is that the set only covers ophthalmic prisms (those of a small enough magnitude to be glazed into spectacles) in very fine increments. Although the uses are almost endless, it finds special utility in your refraction routine for patients requiring prisms or children for the 10PD BO test.


Having determined the prism apparently required, the optom offers the prism (or extra prism) to the patient over their current specs.


There are no distractions from the rim/aperture of the trial lens and no narrowing of the binocular field of vision, which render the patients judgement pretty equivocal as these factors frustrate sensory fusion (one of the things we are often trying to improve with the prism).


Presenting the prism in this way, I found the patient’s subjective judgement is a much better predictor of tolerance in the new spectacles, thus saving unnecessary retests.


As for the 10PD Base Out test, it’s just so much easier to see the movement in the challenging cases. In the simple cases a trial lens 10PD will suffice instead.


The prisms are made in glass (for durability and optical quality [lower chromatic aberration than plastic]) with great accuracy. They are thin and easy to handle, with the power in PD engraved on.


Small enough to fit in the central well of the trial lens case, this set can be there when you need it…not every patient, but at some point each day you work.


Box measures 20 x 5.5 x 7cm. 2 x prisms in 0.5,1,1.5,2,2.5,3,3.5,4PD and a single prism in powers of 5, 10,15 & 20PD. By presenting the prism either monocularly or binocularly (where necessary) all total prism values between 0 and 24 PD can be obtained in 0.5PD increments.


Lenses in excellent condition (essentially perfect)