Measurement of bifocal intraocular lens modulation transfer function using a charge-coupled device

William J. Neubert; Jim L. McGarvey; George F. Green

doi:10.1117/12.176830

26 May 1994 Measurement of bifocal intraocular lens modulation transfer function using a charge-coupled device

William J. Neubert, Jim L. McGarvey, George F. Green

Proceedings Volume 2127, Ophthalmic Lens Design and Fabrication II; (1994) https://doi.org/10.1117/12.176830
Event: OE/LASE '94, 1994, Los Angeles, CA, United States

Abstract

The special equipment requirements and limitations for bifocal intraocular lens MTF measurement using a CCD detector are discussed. Proper MTF measurement requires that at least 90% of the energy passing through the lens aperture be imaged within the sampled area of the sensor. Spectral filtering of optical density greater than 2.5 sufficiently eliminates out-of-band radiance. Well-corrected relay optics of numerical aperture at least twice that of the lens under test and a calibrated image scale are important for accurate results. Significant modulation losses at spatial frequencies well below the Nyquist sampling occur due to pixel geometry, blooming, and charge transfer inefficiency. for a bifocal intraocular lens, where the overall blur pattern may be as large as 0.5 mm, these factors can limit the ability to accurately compute modulation at spatial frequencies greater than 100 cycles/mm. Correction of equipment-induced modulation losses can be realized through improved data processing. Use of MTF measurement for quality control of the Storz TRUE VISTA ^TM bifocal intraocular lens is discussed. Results agree with theoretical expectations to within 10% modulation. Sensitivity to defects such as astigmatism and zone defects are demonstrated at low spatial frequencies.

Citation Download Citation

William J. Neubert, Jim L. McGarvey, and George F. Green "Measurement of bifocal intraocular lens modulation transfer function using a charge-coupled device", Proc. SPIE 2127, Ophthalmic Lens Design and Fabrication II, (26 May 1994); https://doi.org/10.1117/12.176830

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