Initial Surface Temperature of PMMA Plates Used for Daily Laser Calibration Affects the Predictability of Corneal Refractive Surgery

Wernli, Jeremy; Schumacher, Silvia; Wuellner, Christian; Donitzky, Christof; Mrochen, Michael

doi:10.3928/1081597x-20120823-02

Cited by 11 publications

(6 citation statements)

References 19 publications

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“…It is important to observe that, in the current study, the ocular surface temperature was measured using a high speed infra-red camera with a frame-rate of 350 images per second and a 750 Hz excimer laser, i.e., the camera was capable of capturing almost every second pulse. This is important as the highest frame rate of the camera reportedly used in similar experiments till date was 50 frames per second 6, 7, 18, 19. Despite the high speed, high resolution and high accuracy of the infrared camera, errors in the measurements and inferences may appear from the errors in the estimation of the emissivity factor of human cornea (∼0.9), estimation of the change of the emissivity factor of human corneas with the corneal curvature, viewing angle of the camera, precise position of the eye as the eye moves during measurement, etc.…”

Section: Discussionmentioning

confidence: 99%

“…To the best of our knowledge, this is the first paper to clinically document ocular surface temperature changes at high repetition rate of 750 Hz (Previous clinical studies have documented temperature changes up to 500 Hz) 7, 10. In addition, this is the first study to use a high resolution infrared thermal camera with a high frame-rate of 350 images per second allowing capture of thermal images after almost every other laser spot (previous studies have used much lower frame rates of up to 50 frames per second) 6, 7, 18, 19…”

Section: Introductionmentioning

confidence: 92%

See 1 more Smart Citation

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

Ortueta¹,

Arba-Mosquera

Magnago

2019

Journal of Optometry

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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.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 92%

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

Ortueta¹,

Arba-Mosquera

Magnago

2019

Journal of Optometry

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“…Es importante efectuar una calibración diaria del láser, la cual consiste en realizar una ablación en un plato de prueba de plástico de material PMMA. Estudios científicos indican que la temperatura ideal de las placas de PMMA debe estar comprendida entre ±5 ºC para evitar fallos de refracción visualmente significativos debido al error en la calibración (Wernli, Schumacher, Wuellner, Donitzky y Mrochen, 2012).…”

Section: Mantenimientounclassified

Variables y parámetros influyentes en los perfiles de ablación del láser de excímeros

Tomás-Juan¹

2014

Cienc. Tecnol. Salud Vis. Ocul.

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<p>El láser de excímeros permite corregir los errores refractivos miópicos, astigmáticos e hipermetrópicos mediante la ablación de la superficie corneal. Para conseguir el mejor tratamiento y la mejor corrección visual postoperatoria es necesario un buen mantenimiento y calibración de todos los parámetros del láser y de los factores ambientales de la sala de quirófano. Después de la cirugía en algunas situaciones se produce un incremento de las aberraciones, las cuales afectan en gran medida a la calidad visual del paciente. En la actualidad nuevos dispositivos basados en la ablación guiada por frente de onda y la ablación topográfica se han introducido con el objetivo de disminuir las aberraciones postoperatorias. En el presente trabajo se realiza un análisis de los principales parámetros del láser de excímeros que influyen en la ablación, como los diferentes perfiles de ablaciones corneales, que muestran cómo se relacionan directamente con la calidad visual posquirúrgica.</p><p> </p>

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“…Vetrugno et al 24 reported that "high-repetition-rate excimer laser systems require spot sequences with optimized temporal and spatial spot distribution to minimize the increase in OST." Wernli et al 25 evaluated the effects of initial surface temperature of poly-methyl-methacrylate (PMMA) plates used for daily laser calibration. They found that the ablation depth increased linearly from 73.9 to 96.3 μm within a temperature increase from 10.1°C to 75.7°C (increase rate of 0.3192 μm∕K).…”

Section: Introductionmentioning

confidence: 99%

Analysis of the change in peak corneal temperature during excimer laser ablation in porcine eyes

Arba-Mosquera

Verma

2015

J. Biomed. Opt.

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The objective is to characterize the impact of different ablation parameters on the thermal load during corneal refractive surgery by means of excimer laser ablation on porcine eyes. One hundred eleven ablations were performed in 105 porcine eyes. Each ablation was recorded using infrared thermography and analyzed mainly based on the two tested local frequencies (40 Hz, clinical local frequency; 1000 Hz, no local frequency). The change in peak corneal temperature was analyzed with respect to varying ablation parameters [local frequency, system repetition rate, pulse energy, optical zone (OZ) size, and refractive correction]. Transepithelial ablations were also compared to intrastromal ablations. The average of the baseline temperature across all eyes was 20.5°C±1.1 (17.7°C to 22.2°C). Average of the change in peak corneal temperature for all clinical local frequency ablations was 5.8°C±0.8 (p=3.3E-53 to baseline), whereas the average was 9.0°C±1.5 for all no local frequency ablations (p=1.8E-35 to baseline, 1.6E-16 to clinical local frequency ablations). A logarithmic relationship was observed between the changes in peak corneal temperature with increasing local frequency. For clinical local frequency, change in peak corneal temperature was comparatively flat (r 2 =0.68 with a range of 1.5°C) with increasing system repetition rate and increased linearly with increasing OZ size (r 2 =0.95 with a range of 2.4°C). Local frequency controls help maintain safe corneal temperature increase during excimer laser ablations. Transepithelial ablations induce higher thermal load compared to intrastromal ablations, indicating a need for stronger thermal controls in transepithelial refractive procedures.

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Initial Surface Temperature of PMMA Plates Used for Daily Laser Calibration Affects the Predictability of Corneal Refractive Surgery

Cited by 11 publications

References 19 publications

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

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

Variables y parámetros influyentes en los perfiles de ablación del láser de excímeros

Analysis of the change in peak corneal temperature during excimer laser ablation in porcine eyes

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