Ophthalmic Instruments

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Ophthalmic Instruments Ex Vivo Retinal Pigment
Epithelium Autofluorescence

• By Andrew Williams
• University of Rochester
• Primary Investigator Dr. David Williams, PhD
• Mentor Dr. Jennifer Hunter, PhD
• Home Institution Xavier University of Louisiana

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Autofluorescence

• The Retinal Pigment Epithelium nourishes the rods
  and cones.
• It develops a substance called lipofuscin.
• It is the lipofuscin in the cells causing the
  light emitted onto the retina to autofluoresce.

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RPE Pre-exposure image
Courtesy Jessica Morgan
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150 uW Exposure for 15 minutes
Courtesy Jessica Morgan
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RPE immediately Post-exposure Image

• Dimming is a phenomenon that occurs in vivo and
  ex vivo for light intensities of 18.8 mW/cm2 on
  the retina.
• These light intensities were expected to be safe.

Courtesy Jessica Morgan
150 uW Exposure Location
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Goals

• What are the light exposures of ophthalmic
  devices currently used in retinal surgery?
• Do they cause dimming ex vivo?

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Methods Dimming Ex Vivo
Exposure
Imaging
1º Field of View
1º Field of View

• Power levels of the imaging light source were
  recorded to ensure safe light exposures would be
  used to image the retina.
• Images of the retina were taken at a 1º field.
  Block half of the image and expose area for 15
  min. Then take a post image of the full 1º field.

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RPE Pre-Exposure Image
20 Gauge B L Millennium Exposure Location
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Fluorescence Half Blocked Exposure Image
20 Gauge B L Millennium Exposure Location
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RPE Post-Exposure Image
20 Gauge B L Millennium Exposure Location
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Conclusions

• For the Bausch Lomb Millennium, dimming does
  not occur in retinal pigment epithelium ex vivo
  at the exposure time of 15 minutes.
• More trials are necessary to confirm that dimming
  occurs for the Photon light source.
• There is a continued quest for light intensities
  and light exposure durations that are safe for
  the human retina in vivo.

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Acknowledgements

• I would like to thank
• Dr. Jennifer Hunter, PhD
• Dr. David Williams, PhD
• Jessica Morgan
• Dr. Mina Chung, MD
• Ben Masella
• Bob Wolfe
• Lana Nagy
• Dr. William Fischer
• Funding Provided through the Center for Adaptive
  Optics, a National Science Foundation Science
  and Technology Center (STC) AST-987683
• And rest of the Center for Visual Science and
  Center for Adaptive Optics family that helped to
  make my research in Rochester, NY successful!

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References

• Bennett, Arthur G. Clinical Visual Optics.
  Butterworths Inc. Second Ed. 1989. pp. 9-22, pp.
  359-390
• Rodieck, R. W. The Vertebrate Retina
  Principles of Structure and Function. W. H.
  Freeman and Company. 1973. pp. 288-295
• Delori, Francois C. Maximum permissible
  exposures for ocular safety (ANSI 2000), with
  emphasis on ophthalmic devices. Optical Society
  of America. Vol. 24, No. 5. May 2007. pp
  1250-1265
• Inoue, Y. A2e mediated phototoxic effects of
  endoilluminators. Br. J. Ophthalmol. Vol. 90.
  February 2006. pp. 229-232
• Lamb, Laura E. A2e A Component of Ocular
  Lipofuscin. Photochemistry and Photobiology.
  Vol. 79. 2004. pp. 127-136.
• Endoilluminator. http//www.retinalphysician.com
  /article.aspx?article100050
• Endoilluminator. http//www.vision-surgery.com/t
  echnology-millennium.html
• Mathematics. http//en.wikipedia.org/wiki/Mathem
  atics/