Three-Month Clinical Outcomes to Correct Myopia or Myopic Astigmatism Using a Femtosecond Laser for Lenticule Creation With Automated Centration and Cyclotorsion Compensation.

PURPOSE: To individually evaluate the clinical outcomes for right and left eyes in the first 3 months after laser-assisted lenticule extraction for myopia and myopic astigmatism with the use of the new ATOS femtosecond laser system (Smart-Sight; SCHWIND eye-tech-solutions). METHODS: A total of 331 eyes from 168 patients (166 right eyes and 165 left eyes) consecutively treated with SmartSight lenticule extraction were retrospective analyzed after a 3-month follow-up period. Patients' mean age was 26 ± 6 years (range: 18 to 47 years) and mean preoperative spherical equivalent (SEQ) was -5.07 ± 1.92 diopters [D] (range: -1.50 to -11.25 D) with a mean astigmatism of -1.04 ± 0.85 D (range: 0.00 to -4.00 D). At 3 months of follow-up, visual acuity, SEQ and cylinder, safety index, efficacy index, corneal higher order aberrations, and intraocular pressure (IOP) were analyzed. Furthermore, refractive and visual outcomes were also analyzed for the right and left eyes individually. All lenticule extraction treatments were performed with the SmartSight treatment method of the SCHWIND ATOS femtosecond laser. RESULTS: At 3 months after surgery, mean SEQ was -0.12 ± 0.19 D and 98% of eyes were within ±0.50 D of the SEQ. All eyes were within ±1.00 D of the SEQ. Astigmatism of 0.50 D or less was achieved in 99% of eyes. The change in Snellen lines (difference between preoperative corrected distance visual acuity and postoperative uncorrected distance visual acuity) showed a gain of one or more lines in 13% and in 85% of the eyes the same was achieved. There was a loss of one or more lines at 3 months of follow-up in 1.6%. The safety index was 1.03 and efficacy index was 1.02. No significant difference between the right and left eyes was found. CONCLUSIONS: The 3-month follow-up data show that SmartSight treatment for correction of myopia and myopic astigmatism with the SCHWIND ATOS is a safe, efficient, and accurate procedure. It provided excellent results in terms of visual recovery, predictability, and higher order aberrations. [J Refract Surg. 2024;40(1):e30-e41.].

High-speed recording of thermal load during laser trans-epithelial corneal refractive surgery using a 750Hz ablation system / Registro de alta velocidad de la carga térmica durante la cirugía refractiva corneal transepitelial con láser utilizando un 750Sistema de ablación Hz

Purpose: To evaluate the temperature rise of human cornea during trans-epithelial photorefractive keratectomy (trans-PRK) with a 750 Hz 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 750 Hz 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 6000 nl, 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

Objetivo: Evaluar el aumento de temperatura de la córnea humana durante la queratectomía transepitelial fotorrefractiva (trans-PRK) con láser excimer de 750 Hz, utilizando software para el control inteligente del efecto térmico (ITEC). Métodos: En esta serie de casos observacional, se practicó ablación Trans-PRK en 5 ojos de 3 pacientes, utilizando un perfil asférico de un sistema láser excimer de 750 Hz. Se utilizó una cámara de infrarrojos de alta resolución con 350 fotogramas por segundo para determinar la temperatura de la superficie corneal. Las imágenes se tomaron de forma secuencial, iniciándose unos pocos segundos antes de la ablación y finalizando unos pocos segundos tras la misma. Se registró la temperatura máxima de cada pixel de una imagen dada, realizándose un gráfico con respecto al tiempo. Resultados: La temperatura basal de la superficie ocular, inmediatamente antes del comienzo de la aplicación del láser excimer, osciló entre 32 °C y 34,9 °C. La temperatura máxima de la superficie ocular, hasta la ablación del epitelio, osciló entre 35,2 °C y 39,7 °C. La temperatura máxima de la superficie ocular durante la ablación del estroma con láser de alta y baja fluencia osciló entre 32,9 °C y 36,5 °C y entre 34,4 °C y 37,7 °C, respectivamente. Conclusión: El software ITEC es efectivo para controlar el aumento de la temperatura máxima durante la ablación por láser en la compleja situación que acontece durante el procedimiento de trans-PRK, implicando volúmenes de alta ablación de cerca de 6000 nl, y mejorando potencialmente los resultados. El sistema ITEC limitó la temperatura máxima a 39,7°C en el epitelio, y a 37,7°C en el estroma. La temperatura epitelial fue siempre superior a la temperatura estromal (independientemente de la irradiación de alta o baja fluencia). No se alcanzó nunca el límite de de seguridad de 40 °C descrito en la literatura

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

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.

Transepithelial Photorefractive Keratectomy in Moderate to High Astigmatism With a Non-wavefront-Guided Aberration-Neutral Ablation Profile.

PURPOSE: To evaluate the outcomes of transepithelial photorefractive keratectomy (PRK) in moderate to high astigmatism with a non-wavefront-guided aberration-neutral ablation profile using SmartPulse allocation. METHODS: In this retrospective study, myopic patients with a preoperative cylinder of 2.00 diopters (D) or greater were analyzed at 3 months of follow-up. Transepithelial PRK treatments were performed in each patient with the Amaris 1050RS laser (SCHWIND eye-tech-solutions, Kleinostheim, Germany) creating aspheric ablation profiles by applying a SmartPulse allocation. Standard examinations and wavefront analyses were included for low and high ocular residual astigmatism subgroups. RESULTS: Fifty-eight eyes (44 patients) were included in the cohort. The eyes were divided into separate ocular residual astigmatism subgroups: 17 eyes presented with less than 0.50 D (low ocular residual astigmatism) and 24 eyes with greater than 0.75 D (high ocular residual astigmatism). The mean refractive cylinder in the entire cohort was 2.84 ± 0.86 D preoperatively and 0.40 ± 0.39 D postoperatively, with 81% of the eyes within 0.75 D of the target astigmatism. At 3 months of follow-up, significant improvement (P < .05) was seen in terms of sphere, cylinder, spherical equivalent, and uncorrected (UDVA) and corrected (CDVA) distance visual acuity. CDVA improved in 40% of eyes and 3% of eyes lost one line of CDVA. No clinically relevant changes were seen in higher order aberrations. The refractive changes showed an excellent match with the keratometric changes. The difference between the low and high ocular residual astigmatism subgroups was not significant except for the change of Snellen lines of CDVA (P < .05). CONCLUSIONS: Transepithelial PRK using a non-wavefront-guided aberration-neutral ablation profile performed by applying SmartPulse allocation yielded excellent visual outcomes. The preoperative astigmatism was reduced to subclinical values. Both subgroups were effective in terms of UDVA, CDVA, spherical and astigmatic correction, and preserving higher order aberrations. However, the low ocular residual astigmatism subgroup was slightly more prone to gain lines of CDVA. [J Refract Surg. 2018;34(7):466-474.].

Thermodynamic measurement after cooling the cornea with intact epithelium and lid manipulation / Monitorización termodinámica tras el enfriamiento de la córnea con el epitelio intacto y manipulación del párpado

Purpose: To characterize the rate of change of ocular surface temperature (OST) under lid manipulation after cooling the intact cornea with balanced salt solution (BSS). Methods: In a patientfor refractive surgery, priorto the ablation,the temperature ofthe cornea was continuously recorded with a high speed infrared (350 Hz) camera. Two millilitre of chilled BSS with a temperature of 8.6 ◦Celsius (◦C) was instilled for about 3 s. Using exponential functions, the three contributions have been determined, subjacent corneal layers, environment, and chilled BSS. Results: The mean temperature of the cornea preoperatively was 34.5 ◦C. After applying the chilled BSS the temperature decreased about 14 ◦C down to an OST of 20 ◦C and the time needed afterwards to get the normal (OST) temperature of about 30 ◦C was 40 s. Due to the inserted speculum and missing blink, OST did not reach the original OST of 34.5 ◦C and faded at about 32.5 ◦C. According to our best fitted model, absolute value of each contributing component was 31.4 ◦C (subjacent corneal layers), 26.8 ◦C (environment) and 8.6 ◦C (BSS). Conclusions: Applying chilled BSS to the cornea quickly reduces the temperature of the cornea with a thermal relaxation time of 3 s and a amplitude decrease of 8.6 ◦C. This together with a relaxation time of 7s for subjacent corneal layers, and 184 s for environment after instillation of BSS combined with a well-controlled environment provides a period of 40 s of corneal temperature below baseline, which may be of clinical benefit when applying chilled BSS immediately before or immediately after ablation (AU)

Objetivo: Describir el índice de cambio de la temperatura de la superficie ocular (OST) con manipulación del párpado tras el enfriamiento de la córnea intacta con solución salina balanceada (BSS). Métodos: En un paciente sometido a cirugía refractiva, con anterioridad a la ablación, registramos continuamente la temperatura de la córnea con una cámara de infrarrojos de alta velocidad (350 Hz). Instilamos durante alrededor de 3 s dos mililitros de BSS a una temperatura de 8,6◦ Celsius (◦C). Utilizando funciones exponenciales, se determinaron los valores de las tres contribuciones: capas corneales subyacentes, ambiente, y BSS fría). Resultados: Preoperatoriamente, la temperatura media de la córnea fue de 34,5 ◦C. Tras aplicar la BSS fría, la temperatura descendió alrededor de 14 ◦C hasta alcanzar una OST de 20 ◦C, precisándose un tiempo posterior de 40 segundos para alcanzar la OST normal de unos 30 ◦C. Debido a la inserción del espéculo y a la ausencia de parpadeo, la OST no alcanzó el valor original de 34,5 ◦C, permaneciendo en unos 32,5 ◦C. De acuerdo a nuestro modelo de mejor ajuste, el valor absoluto de cada componente participante fue de 31,4 ◦C (capas corneales subyacentes), 26,8 ◦C (ambiente) y 8,6 ◦C (BSS). Conclusiones: La aplicación de BSS fría a la córnea reduce rápidamente la temperatura de la misma, con un tiempo de relajación térmica de 3 s y un descenso de amplitud de 8,6 ◦C. Estos hallazgos, junto con tiempos de relajación de 7 s para las capas corneales subyacentes, y de 184 s para el ambiente tras la instilación de BSS, junto con un entorno bien controlado, proporciona unos 40 s de temperatura corneal inferior a la basal, lo que puede suponer un beneficio clínico cuando se aplica BSS fría inmediatamente antes o inmediatamente después de la ablación (AU)

Thermodynamic measurement after cooling the cornea with intact epithelium and lid manipulation.

PURPOSE: To characterize the rate of change of ocular surface temperature (OST) under lid manipulation after cooling the intact cornea with balanced salt solution (BSS). METHODS: In a patient for refractive surgery, prior to the ablation, the temperature of the cornea was continuously recorded with a high speed infrared (350Hz) camera. Two millilitre of chilled BSS with a temperature of 8.6°Celsius (°C) was instilled for about 3s. Using exponential functions, the three contributions have been determined, subjacent corneal layers, environment, and chilled BSS. RESULTS: The mean temperature of the cornea preoperatively was 34.5°C. After applying the chilled BSS the temperature decreased about 14°C down to an OST of 20°C and the time needed afterwards to get the normal (OST) temperature of about 30°C was 40s. Due to the inserted speculum and missing blink, OST did not reach the original OST of 34.5°C and faded at about 32.5°C. According to our best fitted model, absolute value of each contributing component was 31.4°C (subjacent corneal layers), 26.8°C (environment) and 8.6°C (BSS). CONCLUSIONS: Applying chilled BSS to the cornea quickly reduces the temperature of the cornea with a thermal relaxation time of 3s and a amplitude decrease of 8.6°C. This together with a relaxation time of 7s for subjacent corneal layers, and 184s for environment after instillation of BSS combined with a well-controlled environment provides a period of 40s of corneal temperature below baseline, which may be of clinical benefit when applying chilled BSS immediately before or immediately after ablation.

Determination of the excimer laser ablation rate in previously cross-linked corneas.

PURPOSE: To evaluate the need for and quantify the extent of nomogram adjustments to compensate for potential changes in the amount of effective corneal stroma ablated in previously cross-linked corneas. METHODS: Ex vivo porcine corneas were divided into two groups (the corneal cross-linking [CXL] group, n = 30; and the control group, n = 3): these experimental corneas underwent CXL including deepithelialization, instillation of riboflavin solution for 25 minutes, and ultraviolet-A irradiation at 9 mW/cm2 for 10 minutes. The control group was deepithelialized only. Four consecutive excimer laser ablations of 50 pm each were performed (AMARIS 750S; SCHWIND eye-tech-solutions, Kleinostheim Germany), and stromal bed thickness was measured with a built-in optical coherence pachymeter. To determine the potential influence of riboflavin, a third group (the riboflavin group, n = 12) underwent deepithelialization and instillation of riboflavin, but no ultraviolet-A irradiation. RESULTS: The mean individual ablation depth across the four ablations was significantly smaller in cross-linked corneas (-17%) when compared to untreated control corneas (P < .001). A consistent reduction of 12% was observed via a cumulative analysis when assessing the relative isolated effect of CXL on the ablation rate. There was no significant effect from riboflavin in the deeper ablations, except for the first ablation (68.6 + 1.1 mm [range: 1 to 50 pm]). This may be due to a measurement error in pachymetric readings due to the thin film of riboflavin on the surface that resists even extensive rinsing. CONCLUSIONS: CXL reduces the corneal ablation depth of excimer lasers in the anterior 200 pm of the porcine cornea by approximately 12%. Further clinical studies are needed to validate these findings in human corneas.

Safety, efficacy, and predictability of laser in situ keratomileusis to correct myopia or myopic astigmatism with a 750 Hz scanning-spot laser system.

PURPOSE: To evaluate the clinical outcomes of laser in situ keratomileusis (LASIK) to correct myopia or myopic astigmatism using the Amaris 750S 750 Hz excimer laser. SETTING: Private LASIK center, Tokyo, Japan. DESIGN: Case series. METHODS: Patients with myopia or myopic astigmatism (spherical equivalent -0.50 to -11.63 diopters [D]), a corrected distance visual acuity (CDVA) of 20/20 or better, and an estimated residual bed thickness of 300 µm or more had LASIK using the aspheric aberration-free ablation profile of the 750 Hz scanning-spot laser and the Femto LDV Crystal Line femtosecond laser for flap creation. Study parameters included uncorrected distance visual acuity (UDVA), CDVA, manifest refraction, astigmatism, and higher-order aberrations (HOAs). RESULTS: The study included 1280 eyes (685 patients). At 3 months, 96.6% of eyes had a UDVA of 20/20 or better and 99.1% had 20/32 or better; 94.1% of eyes were within ± 0.50 D of the intended correction and 98.9% were within ± 1.00 D; 89.7% of eyes had no residual cylinder and 96.0% had a postoperative astigmatism of less than 0.50 D. All eyes had a postoperative CDVA of 20/20 or better. The HOAs increased postoperatively (P<.001), with mean total postoperative corneal and ocular HOAs of 0.66 µm ± 0.20 (SD) and 0.56 ± 0.23 µm, respectively. The efficacy index and safety index were 1.02 and 1.06, respectively. CONCLUSION: Laser in situ keratomileusis with the 750 Hz scanning-spot laser was safe, effective, and predictable. No specific clinical side effects that might be associated with a high repetition rate occurred. FINANCIAL DISCLOSURE: Mr. Magnago is an employee of Schwind eye-tech-solutions GmbH. No other author has a financial or proprietary interest in any material or method mentioned.

Influence of stromal refractive index and hydration on corneal laser refractive surgery.

PURPOSE: To evaluate the influence of the stromal refractive index and hydration on postoperative outcomes in eyes that had corneal laser refractive surgery using the Amaris laser system. SETTING: Augenzentrum Recklinghausen, Recklinghausen, Germany. DESIGN: Comparative case series. METHODS: At the 6-month follow-up, right eyes were retrospectively analyzed. The effect of the stromal refractive index and hydration on refractive outcomes was assessed using univariate linear and multilinear correlations. RESULTS: Sixty eyes were analyzed. Univariate linear analyses showed that the stromal refractive index and hydration were correlated with the thickness of the preoperative exposed stroma and was statistically different for laser in situ keratomileusis and laser-assisted subepithelial keratectomy treatments. Univariate multilinear analyses showed that the spherical equivalent (SE) was correlated with the attempted SE and stromal refractive index (or hydration). Analyses suggest overcorrections for higher stromal refractive index values and for lower hydration values. CONCLUSIONS: The stromal refractive index and hydration affected postoperative outcomes in a subtle, yet significant manner. An adjustment toward greater attempted correction in highly hydrated corneas and less intended correction in low hydrated corneas might help optimize refractive outcomes. FINANCIAL DISCLOSURE: Mr. Magnago and Dr. Arba-Mosquera are employees of and Dr. Diego de Ortueta is a consultant to Schwind eye-tech-solutions GmbH & Co. KG. Mr. Rüden has no financial or proprietary interest in any material or method mentioned.

Clinical results of using a high-repetition-rate excimer laser with an optimized ablation profile for myopic correction in 10 235 eyes.

PURPOSE: To evaluate the visual outcomes, safety, stability, efficacy, and predictability of laser in situ keratomileusis (LASIK) to correct myopia using a high-repetition-rate excimer laser with an optimized ablation profile. SETTING: Private clinic, Tokyo, Japan. DESIGN: Retrospective noncomparative study. METHODS: In this study, patients had LASIK using the Schwind Amaris excimer laser for myopic correction. RESULTS: The study comprised 10 235 eyes of 5191 patients. The patients' mean age was 33.9 years ± 7.84 (SD) (range 18 to 56 years). The mean preoperative manifest refraction spherical equivalent (MRSE) was -5.02 ± 2.17 diopters (D) (range -2.75 to -11.50 D). Three months postoperatively, 82.0% of patients achieved an uncorrected distance visual acuity of -0.18 logMAR or better and 96.9% achieved 0.00 logMAR or better. The MRSE was within ±0.50 D of the intended refractive target in 88.4% of eyes and within ±1.00 D in 98.8%. Despite using the profile designed to minimize postoperative aberrations, the postoperative corneal and ocular higher-order aberrations increased. CONCLUSION: Laser in situ keratomileusis using a high-repetition-rate excimer laser was a safe and effective procedure, yielding predictable results for a wide range of myopic patients. FINANCIAL DISCLOSURE: Mr. Magnago is an employee of Schwind Eye-Tech Solutions GmbH & Co. KG. No other author has a financial or proprietary interest in any material or method mentioned.

Supplementary effect of static cyclotorsion compensation with dynamic cyclotorsion compensation on the refractive and visual outcomes of laser in situ keratomileusis for myopic astigmatism.

PURPOSE: To evaluate the add-on effect of static cyclotorsion compensation (SCC) over dynamic cyclotorsion compensation (DCC) on the refractive and visual outcomes in patients having laser in situ keratomileusis (LASIK) for myopic astigmatism. SETTING: Private center, Tokyo, Japan. DESIGN: Comparative study. METHODS: Consecutive patients had LASIK with a target of emmetropia between August 2009 and June 2010. Patients had preoperative myopic astigmatism of 2.0 diopters (D) or greater and more than 3 months of follow-up. Patients had SCC plus DCC treatment (study group) or DCC treatment only (control group). RESULTS: The 2 groups were similar preoperatively in refraction, visual acuity, and higher-order aberrations (HOAs). After treatment, the refractive outcome in the study group was significantly better than in the control group, with a mean sphere of 0.13 D ± 0.29 (SD) versus 0.17 ± 0.30 D (P=.009), a mean cylinder of -0.11 ± 0.29 D versus -0.19 ± 0.36 D (P<.001), and a mean spherical equivalent of 0.07 ± 0.29 D versus 0.08 ± 0.32 D (P=.020). Astigmatism vector analysis also yielded better outcomes in the study group. However, the 2 groups were statistically similar in postoperative uncorrected and corrected visual acuities and induced HOAs. The mean static cyclotorsion value in the study group was 2.29 ± 1.74 degrees (range 0 to 11.1 degrees). CONCLUSION: The combination of SCC and DCC using an aberration-free aspheric ablation profile produced a statistically significant improvement in astigmatism outcomes.

In vivo measurements of thermal load during ablation in high-speed laser corneal refractive surgery.

PURPOSE: To evaluate the thermal load of ablation in high-speed laser corneal refractive surgery with the AMARIS excimer laser (SCHWIND eye-tech-solutions). METHODS: Thermal load from refractive corrections on human corneas using a 500-Hz laser system with a fluence of 500 mJ/cm(2) and aspheric ablation profiles was recorded with an infrared thermography camera. Each single in vivo measurement was analyzed and temperature values were evaluated. RESULTS: Overall, the maximum temperature change of the ocular surface induced by the refractive ablations was ≤4°C. The increase in the peak temperature of the ocular surface never exceeded 35°C in any case. This low thermal load was independent of the amount of correction the eye achieved. CONCLUSIONS: The thermal load of the ablation in high-speed laser corneal refractive surgery was minimized using a computer algorithm to control the peak temperature to avoid corneal collagen denaturation with minimal compromise on treatment duration.