Analysis of an adjustable slit design for correcting astigmatism

Terrance N. Clapham, John D'Arcy, Lorne Bechtel, Hermann Glockler, Charles R. Munnerlyn, Peter J. McDonnell, Jenny Garbus

Research output: Contribution to journalConference articlepeer-review

3 Scopus citations


Using 193 nm Excimer Laser light to reshape the cornea has been shown to be an effective way to correct myopia in humans. One way to achieve the controlled shape is to create a large diameter Excimer beam, and pass it through a computer controlled iris diaphragm. As the diaphragm closes, progressively less laser pulses reach the outer portions of the treatment area, while all the pulses reach the center region, effectively flattening the cornea. The resultant correction is spherical, and does not correct astigmatism. This paper discusses the use of a motor controlled slit to correct astigmatism in a similar manner to myopia. The mechanism described combines an iris diaphragm and adjustable slit for correcting myopia, astigmatism, or a combination of the two. The slit mechanism also rotates so the slit axis can be aligned with the patient's astigmatic axis. Initial test medium was PMMA, which has ablation characteristics similar to human stromal tissue.

Original languageEnglish (US)
Pages (from-to)2-7
Number of pages6
JournalProceedings of SPIE - The International Society for Optical Engineering
StatePublished - Jan 1 1991
Externally publishedYes
EventProceedings of Ophthalmic Technologies - Los Angeles, CA, USA
Duration: Jan 21 1991Jan 22 1991

ASJC Scopus subject areas

  • Electronic, Optical and Magnetic Materials
  • Condensed Matter Physics
  • Computer Science Applications
  • Applied Mathematics
  • Electrical and Electronic Engineering


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