In Vivo Measurements of Thermal Load During Ablation in High-speed Laser Corneal Refractive Surgery

Ortueta, Diego de; Magnago, Thomas; Triefenbach, Nico; Arba-Mosquera, Samuel; Sauer, Udo; Brunsmann, U.

doi:10.3928/1081597x-20110906-01

Cited by 35 publications

(36 citation statements)

References 21 publications

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“…Aspherical ablation profiles have been employed to reduce spherical aberration associated with myopic corrections, so most LASIK procedures are performed currently as “wavefront optimized” 8. Further customization of the ablation pattern has been practiced by pairing wavefront eye data to the refractive data chosen to be corrected, as wavefront-guided treatments in pursue of improving visual function in aberrated eyes, or pre-empting wavefront aberrations created by the standard procedures 9,10.…”

Section: Introductionmentioning

confidence: 99%

Topography-modified refraction (TMR): adjustment of treated cylinder amount and axis to the topography versus standard clinical refraction in myopic topography-guided LASIK

Kanellopoulos¹

2016

OPTH

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PurposeTo evaluate the safety, efficacy, and contralateral eye comparison of topography-guided myopic LASIK with two different refraction treatment strategies.SettingPrivate clinical ophthalmology practice.Patients and methodsA total of 100 eyes (50 patients) in consecutive cases of myopic topography-guided LASIK procedures with the same refractive platform (FS200 femtosecond and EX500 excimer lasers) were randomized for treatment as follows: one eye with the standard clinical refraction (group A) and the contralateral eye with the topographic astigmatic power and axis (topography-modified treatment refraction; group B). All cases were evaluated pre- and post-operatively for the following parameters: refractive error, best corrected distance visual acuity (CDVA), uncorrected distance visual acuity (UDVA), topography (Placido-disk based) and tomography (Scheimpflug-image based), wavefront analysis, pupillometry, and contrast sensitivity. Follow-up visits were conducted for at least 12 months.ResultsMean refractive error was −5.5 D of myopia and −1.75 D of astigmatism. In group A versus group B, respectively, the average UDVA improved from 20/200 to 20/20 versus 20/16; post-operative CDVA was 20/20 and 20/13.5; 1 line of vision gained was 27.8% and 55.6%; and 2 lines of vision gained was 5.6% and 11.1%. In group A, 27.8% of eyes had over −0.50 diopters of residual refractive astigmatism, in comparison to 11.7% in group B (P<0.01). The residual percentages in both groups were measured with refractive astigmatism of more than −0.5 diopters.ConclusionTopography-modified refraction (TMR): topographic adjustment of the amount and axis of astigmatism treated, when different from the clinical refraction, may offer superior outcomes in topography-guided myopic LASIK. These findings may change the current clinical paradigm of the optimal subjective refraction utilized in laser vision correction.

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Section: Introductionmentioning

confidence: 99%

Topography-modified refraction (TMR): adjustment of treated cylinder amount and axis to the topography versus standard clinical refraction in myopic topography-guided LASIK

Kanellopoulos¹

2016

OPTH

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“…Therefore, any change that affects the heat loss or gain may affect the corneal temperature. 1,3,4 The normal corneal surface temperature has been reported to range from 32.9 to 36 • C. 5 Under LASIK settings, when lid speculum has been applied, the dynamic heat balance shifts towards heat loss from the cornea to the surrounding cooler air and baseline corneal temperature (prior to initiating surgery) decreases to approximately 31 • C. When excimer laser is initiated, every single pulse adds heat to the cornea and contributes to the marginal increase in the local corneal temperature. 6 Laser refractive surgery is based on the sequential delivery of multiple laser pulses, with each pulse ablating a small amount of corneal tissue and in the process causing a marginal increase in the local corneal temperature around the laser spot.…”

Section: Palabras Clavementioning

confidence: 98%

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

Ortueta

Magnago

Arba-Mosquera

2015

Journal of Optometry

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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.

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“…Más tanulmányok szerint a lézer ismétlési frekvenciája nem bír befolyással a PRK hosszú távú kimenetelére [19]. A repülőpont-technológiával működő lézerek ablatiós algoritmusok segít-ségével csökkentik a szaruhártyán mérhető csúcshőmér-sékletet [10].…”

Section: Megbeszélésunclassified

“…A szaruhártya felszínéről az ablatiókor megjelenő hő-mennyiség a környezet felé hősugárzással és kondukció-val, a szem belseje felé kondukcióval és konvekcióval adódik át [9,10]. A légáramlás sebessége ezért a hűtőha-tást is befolyásolhatja, így a vizsgálat tárgyát képezte a felszíni légáramlási viszonyok megmérése.…”

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A szaruhártya felszíni hőmérséklete és légáramlási viszonyainak alakulása refraktív célú lézeres beavatkozás közben három különböző típusú és ismétlési frekvenciájú excimer lézerberendezésnél

et al. 2016

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Bevezetés: A cornea törőerejének excimer lézerrel történő módosítása közben a termikus viszonyok alakulása fontos tényező lehet a sebgyógyulás és a hosszú távú eredmények szempontjából. Célkitűzés: A tanulmány célja a refraktív műtét során a szaruhártya felszíni hőmérsékletének vizsgálata három különböző lézerplatformnál Módszer: A vizsgá-latot 90 beteg egyik kezelt szemén végezték, amelyeken Carl Zeiss MEL 70 és MEL 80, illetve Wavelight Allegretto típusú lézerrel történt photorefractiv keratectomia kezelés. EBRO TLC 730 infravörös hőmérővel végeztek mérést közvetlenül a hámeltávolítás előtt, valamint közvetlenül a kezelés előtt és után. A betegek átlagéletkora 25,5 ± 3 év volt. Minden fénytörési hiba myopiás vagy myop astigmiás volt, átlaguk -3,2 ± 0,8 Dpt volt. Eredmények: A felszíni cornea hőmérsékletének alakulásában statisztikailag szignifikáns különbség volt a MEL 80 és a másik két típusú lézer között. Következtetések: A lézerkészülékek szöveti gőzök eltávolítására szolgáló elszívórendszere által okozott külön-böző mértékű légáramlási viszonyok befolyásolhatják a hőmérsékleti viszonyainak alakulását. Ez a refraktív eredmé-nyeket nem befolyásolta. Orv. Hetil., 2016, 157(43), 1717-1721. Kulcsszavak: refraktív sebészet, PRK, szaruhártya felszíni hőmérséklete, sebgyógyulásRelationship between corneal surface temperature and air flow conditions during refractive laser eye surgery using three different excimer lasers Introduction: Thermal conditions during photorefractive keratectomy might be an important issue related to the corneal wound healing and long-term outcomes. Aim: Authors tried to find out the importance of temperature conditions during the treatment. Method: One eye of 90 patients has been included into the study. Photorefractive keratoctomy was applied with Carl Zeiss MEL 70, MEL 80 and Wavelight Allegretto excimer lasers. EBRO TLC 730 infrared thermometer was used for the measurement of surface temperature of the cornea before epithelial removal, as well as before and after the treatment. Average age of the patients was 25.5 ± 3 yr. Average myopic correction was -3.2 ± 0.8 Dpt. Results: Statistically significant difference was found in temperature change between MEL 80 and the other two types of excimer laser devices. Conclusions: Different air flow conditions of the smoke removal system might have an influence on changes of the corneal temperature during treatment, but the refractive results were not influenced by this issue.

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In Vivo Measurements of Thermal Load During Ablation in High-speed Laser Corneal Refractive Surgery

Abstract: 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.

Cited by 35 publications

References 21 publications

Topography-modified refraction (TMR): adjustment of treated cylinder amount and axis to the topography versus standard clinical refraction in myopic topography-guided LASIK

Topography-modified refraction (TMR): adjustment of treated cylinder amount and axis to the topography versus standard clinical refraction in myopic topography-guided LASIK

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

A szaruhártya felszíni hőmérséklete és légáramlási viszonyainak alakulása refraktív célú lézeres beavatkozás közben három különböző típusú és ismétlési frekvenciájú excimer lézerberendezésnél

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