The Politzer Telescopic Lens Series
The Politzer bioptic telescope is a new and very interesting approach to telescope design. It has changed the way that we think about designing a low vision telescope. It involves making the “exit pupil” of the telescope larger. The exit pupil id the view of the objective (front) lens through the telescope.
Traditional the eyepiece lens (back side) size is made smaller than the objective or front end of the telescope. Since making the eyepiece lens larger was not believed to make the field of view of the telescope larger or brighter, it was thought that a larger eyepiece was not beneficial.
The images above compare the Politzer 2.2X to a standard Designs for Vision 2.2X bioptic telescope. In each picture the left is a standard 2.2X while the right image is the Politzer 2.2X. The left set demonstrates the much wider eyepiece lens on the Politzer. The right set shows the the front or objective lenses are the same size. The standard bioptic requires the patient to stay carefully aligned with the small eyepiece while the Politzer allows the patient more freedom to "swim" around within the exit pupil.
Above we see the wide eyepiece and thus wide exit pupil of the Politzer Bioptic
Above the overhead view of the Politzer Bioptic System shows that the eyepiece and the objective lens are the same size. This creates a wider exit pupil and thus more ease and comfort in use.
Additionally, most optical designers developed telescopes for the static (non-moving) eye. Low vision patients often have central scotomas, areas of decreased vision. They must often shift their eyes view to focus the view of an object away from the scotoma or blind spot. These movements are confined in traditional telescopes making it more difficult to use and causing more eyestrain in use.
"Design of low powered telescopes to maximize the ease of use regarding less long term strain on the eye requires that the eye swim in an enlarged device exit pupil".
"While the classical optical design calls for a static eye pupil with an iris diameter set by ambient lighting, the philosophical impact of the device exit pupil being close to the iris diameter of the eye is a tunnel appearance of the field. This leads to long term eyestrain and a physiological reduction in the apparent view through the system".
Marvin Hutt, Ph.D., Senior Adjunct Associate Professor of Optical Engineering at the Stevens Institute of Technology, New Jersey
The Politzer Telescopic Lens Series (PTS) has created a new set of spectacle telescopes that are easier and more effective for the patient to use. These new telescopes were developed by Dr. Politzer through Design’s for Vision’s laboratory. They incorporate a large exit pupil by creating a larger eyepiece equal in size to the objective or front lens of the telescope.
Now rather than being forced in a fixed position to view through the telescope, the eye is free to swim about in exit pupil without losing the view through the telescope. The Politzer telescopes create a much more comfortable and natural feel to use.
The Politzer Telescopes are available in 1.7X and 2.2X non-focusable Galilean systems and in 2.2X, 3.3X and 4.0X Micro-spiral versions. These telescopes may benefit many bioptic drivers but also many for whom driving is not a consideration. The ease of use of the Politzer telescopes may make prescribing bioptics easier for many patients who experienced difficulty in using other bioptics.