Ophthalmic Surgery and Lasers

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Volume 30 (4) * April 1999 * Experimental Science (abstract)

Biconcave Contact Lenses: A Critical Analysis of Their Optical Properties

Pascal Rol, PhD; Franz Fankhauser II, MD; Peter Niederer, PhD

BACKGROUND AND OBJECTIVE

The purpose of this experiment was to compare biconcave contact lenses with other contact lenses already used for observation and irradiation of the retina and choroid.

MATERIALS AND METHODS

The optical performance of different biconcave lenses is described in terms of magnification, resolution, and field of view. The optical properties of the eye were taken into account using the Gullstrand’s model of the human eye.

RESULTS

The performance of biconcave contact lenses represents a compromise between that of Goldmann’s and wide angle indirect contact lenses. An upright image, with good peripheral image quality and an intermediate field of view is characteristic of such design. In addition, laser irradiation with large spot sizes is less hazardous when using such negative contact lenses compared to positive lenses of the same absolute refractive power.

CONCLUSION

Biconcave contact lenses qualify as a complement to planoconcave lenses for chorioretinal observation and irradiation tasks. For the same magnification factor, the field of view is smaller than that obtained with indirect contact lenses but the image degradation in the periphery of the retina is reduced.


[Ophthalmic Surg Lasers 1999;30:299-304.]

AUTHORS

From the Department of Ophthalmology, University of Zurich, Switzerland (Drs Rol amd Fankhauser), and the Institute of Biomedical Engineering, Swiss Federal Institute of Technology and University of Zurich, Switzerland (Dr. Niederer).

Accepted for publication November 30, 1998.

Supported in part by the Swiss Commission for Technology and Innovation, Bern, Switzerland, grant 2743.2 (Dr. F. Fankhauser II). Address reprint requests to: Dr. P. Rol, Dept. of Ophthalmology, University of Zurich, Frauenklinikstrasse 24, CH-8091 Zurich, Switzerland.

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