June 2013
Volume 54, Issue 15
Free
ARVO Annual Meeting Abstract  |   June 2013
Selective retina treatment (SRT) automatically controlled by a real-time reflectometry in a rabbit model
Author Affiliations & Notes
  • Young Jung Roh
    Ophthalmology, St Mary's Hospital, Seoul, Republic of Korea
  • Eric Seifert
    Biomedical Optics, University of Lubeck, Lubeck, Germany
  • Theisen-Kunde Dirk
    Biomedical Optics, University of Lubeck, Lubeck, Germany
  • Young Gun Park
    Ophthalmology, St Mary's Hospital, Seoul, Republic of Korea
  • Seungbum Kang
    Ophthalmology, St Mary's Hospital, Seoul, Republic of Korea
  • Ralf Brinkmann
    Biomedical Optics, University of Lubeck, Lubeck, Germany
Investigative Ophthalmology & Visual Science June 2013, Vol.54, 4136. doi:
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      Young Jung Roh, Eric Seifert, Theisen-Kunde Dirk, Young Gun Park, Seungbum Kang, Ralf Brinkmann; Selective retina treatment (SRT) automatically controlled by a real-time reflectometry in a rabbit model. Invest. Ophthalmol. Vis. Sci. 2013;54(15):4136.

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      © ARVO (1962-2015); The Authors (2016-present)

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Abstract
 
Purpose
 

Selective retina therapy (SRT) targets the retinal pigment epithelium (RPE) with repetitive microsecond laser pulses, while causing no thermal damage to the adjacent photoreceptors. Our purpose was to evaluate the safety, selectivity and healing of the retinal lesions by using an automatic dosimetry technique for SRT basing on the evaluation of reflected light during irradiation.

 
Methods
 

Ten eyes of Chinchilla Bastard rabbits were treated with SRT (wavelength: 527 nm, pulse duration: 1.7 µs, repetition rate: 100Hz, max. number of pulses in a burst : 30, pulse energy : 88 µJ, retinal spot diameter : 200 µm) using a Q-switched Nd-YLF laser controlled by real-time reflectometric dosimetry. The technique ramps up the pulse energy within in a burst until microbubble formation is detected and then ceases laser irradiation. After treatment, fundus photography, optical coherence tomography (OCT) and fluorescein angiography (FA) were performed at 3 time points from 1 hour to 3 weeks. Histological analysis was done after 3 weeks.

 
Results
 

Typical fundus photographs obtained 1 hour after irradiation showed that all lesions produced by SRT were not visible ophthalmoscopically at all energy levels used. The lesions could be detected only by angiography. No sign of disruptive effects, such as hemorrhage, was observed. Fundus examination showed focal pigmented speckle due to healing status and no fluorescein leakage after 7 days. OCT images revealed the structure of photoreceptor was preserved, but a disrupted RPE layer as expected. By 3 weeks, histology showed selective RPE damage sparing photoreceptor continuity without inner retinal effects and focally proliferated.

 
Conclusions
 

SRT achieves selective targeting of the RPE without permanent scarring or inner retinal damage. Reflectometry is a reliable noncontact technique to monitor RPE disintegration and may serve as real-time dosimetry control during SRT.

 
 
(A) Fundus image 1 hr after SRT showed invisible laser scar. (B) FA 1 hr after SRT showed significant leakage. (C) OCT showed preservation of the photoreceptor and the inner retina continuity. (D) Histology before SRT. (E) Histology after 3weeks after SRT. The photoreceptor layer was relatively preserved, but the RPE layer focally proliferated (arrow).
 
(A) Fundus image 1 hr after SRT showed invisible laser scar. (B) FA 1 hr after SRT showed significant leakage. (C) OCT showed preservation of the photoreceptor and the inner retina continuity. (D) Histology before SRT. (E) Histology after 3weeks after SRT. The photoreceptor layer was relatively preserved, but the RPE layer focally proliferated (arrow).
 
Keywords: 578 laser • 688 retina  
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