Laser thermokeratoplasty: analysis of in-vitro results and refractive changes achieved in a first clinical study

Ralf Brinkmann; Gerd Geerling; Juergen Kampmeier; Norbert Koop; Benno Radt; Reginald Birngruber

doi:10.1117/12.297840

22 December 1997 Laser thermokeratoplasty: analysis of in-vitro results and refractive changes achieved in a first clinical study

Ralf Brinkmann, Gerd Geerling, Juergen Kampmeier, Norbert Koop, Benno Radt, Reginald Birngruber

Author Affiliations +

Proceedings Volume 3192, Medical Applications of Lasers in Dermatology, Ophthalmology, Dentistry, and Endoscopy; (1997) https://doi.org/10.1117/12.297840
Event: BiOS Europe '97, 1997, San Remo, Italy

Abstract

Laser thermokeratoplasty (LTK) is a minimally invasive method to correct hyperopia and astigmatism. A cw mid-IR laser diode emitting at wavelengths around 1.86 micrometers was used to perform LTK on a first clinical trial. The coagulations were applied to the cornea by means of a specially designed focusing handpiece which was introduced into a corneal application mask fixed by a suction ring. Coagulation patterns consisting of 8 spots per ring were performed with a laser power between 100 - 150 mW and an irradiation time of 10 seconds both on single and on double rings. Significant refractive changes up to 19 D could initially be achieved followed by a strong regression within the first month. Three months post LTK, refractive changes achieved with the single and double ring have stabilized, yielding 1.2 and 1.8 D on the average, respectively. The method reveals only little adverse effects limited to the first days post-op. Force measurements were performed on corneal stripes, which were submerged for 10 s into an oil bath of constant temperature in order to investigate the absolute temperatures required for corneal collagen contraction. Only temperatures exceeding 90 degree(s)C induced a significant force. Analyzing the clinically used LTK parameters by temperature calculations revealed that only a small part of the heated stromal volume experienced sufficient high temperatures to induce significant collagen shrinkage.

Citation Download Citation

Ralf Brinkmann, Gerd Geerling, Juergen Kampmeier, Norbert Koop, Benno Radt, and Reginald Birngruber "Laser thermokeratoplasty: analysis of in-vitro results and refractive changes achieved in a first clinical study", Proc. SPIE 3192, Medical Applications of Lasers in Dermatology, Ophthalmology, Dentistry, and Endoscopy, (22 December 1997); https://doi.org/10.1117/12.297840

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