Spot-size dependence of laser retinal dosimetry

Courant, D.

doi:10.1117/12.2283594

Cited by 3 publications

(3 citation statements)

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“…7,8 The physical reason for this is quite simple: if a small spot is irradiated, the heat can diffuse into surrounding tissue and cool the spot. For some time, it has also been rec-ognized that the retinal damage threshold varies directly as the retinal irradiance and inversely proportional to the retinal image size given constant irradiance.…”

Section: Discussion Of Ocular Riskmentioning

confidence: 99%

Ray tracing of optical aids: Implications for ocular risk

Ritter¹,

Trewhella²

1998

Journal of Laser Applications

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How do ocular aids impact retinal risk when viewing divergent sources? We present ray tracing calculations for ocular aids used in several common configurations and compare risk relative to an unaided eye. Retinal irradiance values for sources of different subtence and divergence were calculated for ocular aids of different magnifying power. The data show the stark difference between point sources, like lasers, and extended sources, such as light emitting diodes ͑LEDs͒ and lamps. Arguing from fundamental physiological phenomena we compare the relative ocular risks of various sources under a range of viewing conditions and compare these calculations with standards proposed to classify such different sources. We conclude that, if point sources are correctly classified, then extended sources, such as LEDs, are overclassified by the IEC 825-1/CENELEC.

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Section: Discussion Of Ocular Riskmentioning

confidence: 99%

Ray tracing of optical aids: Implications for ocular risk

Ritter¹,

Trewhella²

1998

Journal of Laser Applications

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“…Les limites d'exposition les plus faibles correspondent au risque rétinien, défini pour la plage spectrale de 400 à 1400 nm. Dans cette gamme de longueur d'onde, l'influence de la dimension de l'image sur le seuil de lésion introduit des limites différentes pour les sources ponctuelles et étendues (Beatrice et Frisch, 1973 ;Courant et al, 1989b;Zuclich et al, 1999).…”

Section: Les Valeurs Limites D'expositionunclassified

“…Dans le cas de vision d'une source étendue, le danger varie en fonction de la distance entre l'oeil et la source car la diffusion thermique de l'énergie, à l'intérieur des images rétiniennes, devient moins efficace à mesure que leur dimension s'accroît (Sliney et Wolbarsht, 1980;Sliney, 1996;Courant et al, 1989b;Cain et al, 1998). Cette influence du diamètre de l'image rétinienne sur le seuil de lésion n'existe pas dans le cas des lésions photochimiques induites par les rayonnements de 400 à 600 nm.…”

Section: Les Valeurs Limites D'expositionunclassified

Rayonnement laser : risques oculaires et normes de protection

et al. 2000

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RÉSUMÉLes propriétés optiques des tissus biologiques conditionnent de manière importante le risque d'atteinte par le faisceau laser. Les rayonnementii, émis dans I'ultraviolet mais aussi l'infrarouge B et C, représentent un danger pour le segment anté-rieur de l'oeil. Selon la longueur d'onde, le rayonnement est absorbé préférentiel-lement ou exclusivement par la cornée ou le cristallin. The risk for biological tissues to be damaged by a laser beam is mainly determined by their optical properties. Laser radiations emitted in ultraviolet and infrared B and C represent a hazard for the anterior segment of the eye. Depending the wavelength, laser radiation is absorbed by the cornea, the lem or hotb. The lower damage thresholds are reported at the retinal level, in the spectral range of 400 to 1400 nm. The exposure limit values, recommended by laser safety standards, are evaluated with wavelength, exposure duration, puise repetition frequency and the size of the visual angle subtending the source. The fast evolution of laser producîs induces a continuous revision of guidelines.

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Ray tracing of optical aids: Implications for ocular risk

Ritter¹,

Trewhella²

1997

International Laser Safety Conference

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Spot-size dependence of laser retinal dosimetry

Cited by 3 publications

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Ray tracing of optical aids: Implications for ocular risk

Ray tracing of optical aids: Implications for ocular risk

Rayonnement laser : risques oculaires et normes de protection

Ray tracing of optical aids: Implications for ocular risk

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