Lightweight Distometer With Conversion Disc                                        View Shopping Cart

                   

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Distometer (or Vertex Distance) gauge is designed to accurately measure the vertex distance between the cornea and trial lens, or cornea and rear surface of the spectacle Rx lens. The Conversion Disc is used to convert any combination of lens power and vertex distance into an equivalent lens power for a different distance.

Normally a trial lens is placed 5mm to 20mm from the cornea. Spectacle Rx, when fitted correctly, should be between 8mm and 12mm from the cornea. Any difference, however, in vertex distance between the trial lenses and the resultant spectacle Rx produces an error in the effective power of the correction.

The combination of these two devices permits the examiner to measure and then move between any combinations of cornea distance and lens power.

For example, a +12.00D trial lens at 19mm from the cornea must be increased to a +13.00D if placed 11mm from the cornea. As a second example, a -15.00D lens at 15mm vertex distance must be decreased to a -13.00D if placed at 6mm.

The conversion disc supports conversion from a particular combination employed with a trial lens set-up to an equivalent combination in a spectacle Rx. The outer ring shows the lens power (D) and the inner scale shows the + and - lens power, as indicated on each side respectively.

Example:

+15.00D at 12mm = +16.50 D at 6 mm

Includes instructions and conversion calculator. Measures distance between cornea and inside of glasses

5183R   Lightweight Distometer .......... $98.00

Metal Distometer

Distometer Technical Bulletin (pdf)

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