Intraoperative raster photogrammetry—the PAR Corneal Topography System

Michael W. Belin

Research output: Contribution to journalArticlepeer-review

29 Scopus citations


The PAR Corneal Topography System (CTS) is a computer-driven corneal imaging system that uses close-range raster photogrammetry to measure and produce a topographic map of the corneal surface. The CTS determines distortion in a projected two-dimensional grid. Unlike Placido-disc-based videokeratoscopes, the PAR CTS produces a true topographic map (elevation map) and requires neither a smooth reflective surface nor precise spatial alignment for accurate imaging. Because the system uses two noncoaxial optical paths, it can be integrated into other optical devices. A modified CTS was integrated into an experimental erbium: YAG photoablatioe laser. The CTS successfully imaged corneas before, after, and during laser photoablation. Its ability to image nonreflective surfaces and to be integrated into other optical systems may make it suitable for intraoperative refractive monitoring.

Original languageEnglish (US)
Pages (from-to)188-192
Number of pages5
JournalJournal of cataract and refractive surgery
StatePublished - 1993


  • erbium:YAG laser
  • photoablation
  • photogrammetry
  • photorefraction
  • rasterstereography
  • topography
  • videokeratoscope

ASJC Scopus subject areas

  • Surgery
  • Ophthalmology
  • Sensory Systems


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