Determining subjective refraction using dual-wavelength speckle phenomena

Session Details

Session Title: Vision & Accommodation Assessment

Session Date/Time: Monday 24/09/2018 | 14:00-16:00

Paper Time: 14:06

Venue: Room A3, Podium 2

First Author: : U.Oberheide GERMANY

Co Author(s): :    G. Wiel   P. Thiee   O. Kermani   G. Gerten           

Abstract Details

Purpose:

Subjective Refraction is typically obtained by using probe glasses in a trial frame or a phoropter and letter charts. Speckle pattern occur when a coherent light (e.g. from a laser) ist reflected or transmitted through a rough surface. Since this is an interference phenomenum they always appear sharp independent of the actual refraction. When moving the eye the speckles appear to move. As in sciascopy in the same direction for hyperopia, in inverse direction for myopia. Due to chromatic dispersion of the eye there is a focal shift of approx. 0.25 D between red and green light.

Setting:

TH Koeln (Cologne university of applied sciences, institute of applied optics and electronics) and Augenklinik am Neumarkt, Cologne (private eye hospital)

Methods:

A novel system consisting of a dual speckle pattern at two different wavelengths was developped. The subjective refraction of 10 eyes of 5 patients was determined by adding glasses in a trial frame until the two pattern moved in different directions. The determined refraction was compared to autorefractor and phoropter measurements.

Results:

The refraction of all patients could easily be determined. The speed of speckle movement determined the iniatal amount of needed correction which could be more and more refined. The finally achieved subjective refraction was within +-0.25 D in sphere and cylinder for all eyes compared to phoropter and autorefractor measurements.

Conclusions:

Using dual wavelength speckle pattern allows a fast and precise determination of patients subjective refraction without the need of large distances or optotype charts.

Financial Disclosure:

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