Noncontact laser photothermal keratoplasty I: Biophysical principles and laser beam delivery system

Jean-Marie A Parel, Q. Ren, G. Simon

Research output: Contribution to journalArticle

20 Citations (Scopus)

Abstract

BACKGROUND: Thermal shrinkage of stromal collagen is known to produce changes in the corneal curvature. We designed a novel, noncontact laser beam delivery system to perform laser photothermal keratoplasty. MATERIALS AND METHODS: The instrument consistent of a pulsed holmium:YAG laser (2.10- micrometer wavelength, 250-microsecond pulse width, 5-hertz repetition rate) coupled via a monofilament fiber to a common slit-lamp microscope equipped with a polyprism, an adjustable mask, and a projection lens. The system projected an 8-spot annular pattern of infrared laser energy on the cornea to achieve a thermal profile within the stroma and to attain controlled, predictable collagen shrinkage. The system produced treatment patterns of 8 to 32 spots of 150 to 600 μm diameter in concentric rings, continuously adjustable between 3 and 7 mm. The versatility of the system in creating different treatment patterns was tested on thermal paper and human cadaver eyes. RESULTS: A uniform beam profile and different treatment patterns for myopia, hyperopia, and astigmatism were obtained. Myopic correction of 6.00 diopters was demonstrated on cadaver eyes. Corneal topography documented corneal flattening (> 6.00 D) with the following treatment parameters: each spot size on the cornea = 300 μm, radiant exposure of each spot = 18.0 J/cm2, number of pulses = 1, diameter of the treatment ring = 3 mm. CONCLUSIONS: Noncontact slit-lamp microscope laser delivery system for laser photothermal keratoplasty provides flexible and precise selection of laser treatment parameters. It may improve the efficacy of the procedure.

Original languageEnglish
Pages (from-to)511-518
Number of pages8
JournalJournal of Refractive and Corneal Surgery
Volume10
Issue number5
StatePublished - Jan 1 1994
Externally publishedYes

Fingerprint

Corneal Transplantation
Lasers
Hot Temperature
Cadaver
Cornea
Collagen
Therapeutics
Corneal Topography
Hyperopia
Astigmatism
Myopia
Solid-State Lasers
Masks
Lenses

ASJC Scopus subject areas

  • Ophthalmology

Cite this

Noncontact laser photothermal keratoplasty I : Biophysical principles and laser beam delivery system. / Parel, Jean-Marie A; Ren, Q.; Simon, G.

In: Journal of Refractive and Corneal Surgery, Vol. 10, No. 5, 01.01.1994, p. 511-518.

Research output: Contribution to journalArticle

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