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J Optom. 2018 Jul 20. pii: S1888-4296(18)30047-5. doi: 10.1016/j.optom.2018.05.002. [Epub ahead of print]

High-speed recording of thermal load during laser trans-epithelial corneal refractive surgery using a 750Hz ablation system.

Author information

1
AureliosAugenzentrumRecklinghausen, Recklinghausen, Germany. Electronic address: diego.de.Ortueta@augenzentrum.org.
2
SCHWIND eye-tech-solutions, Kleinostheim, Germany.

Abstract

PURPOSE:

To evaluate the temperature rise of human cornea during trans-epithelial photorefractive keratectomy (trans-PRK) with a 750Hz excimer laser employing Intelligent Thermal Effect Control (ITEC) software.

METHODS:

In this observational case series, trans-PRK ablation was performed on 5 eyes of 3 patients using an aspheric profile of a 750Hz excimer laser system. A high-resolution infrared camera with a frame-rate of 350 images per second was used to determine the corneal surface temperature. Images were taken sequentially, starting a few seconds prior to and ending a few seconds after the ablation. The maximum temperature of any pixel of a given image were recorded and graphed against time.

RESULTS:

The baseline ocular surface temperature, immediately prior to the beginning of excimer laser, ranged from 32 to 34.9°C. The maximum ocular surface temperature until the epithelium was ablated ranged from 35.2 to 39.7°C. The maximum ocular surface temperature during stromal ablation with high and low fluence laser ranged from 32.9 to 36.5 and from 34.4 to 37.7°C respectively.

CONCLUSION:

The ITEC software is effective in controlling the maximum temperature rise during laser ablation in the extremely challenging situation of trans-PRK involving high ablation volumes of almost 6000nl, potentially improving the outcomes. The ITEC system limited the maximum temperature to 39.7°C in the epithelium, and 37.7°C in the stroma. The epithelial temperature was always higher than stromal temperature (regardless of high or low fluence irradiation). Safety limit of 40°C found in the literature was never reached.

KEYWORDS:

Carga térmica; Control inteligente del efecto térmico; High speed excimer laser; ITEC; Intelligent Thermal Effect Control; Láser excimer de alta velocidad; Ocular surface temperature; Temperatura de la superficie ocular; Thermal load

PMID:
30037645
DOI:
10.1016/j.optom.2018.05.002
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