June 2017
Volume 58, Issue 8
Open Access
ARVO Annual Meeting Abstract  |   June 2017
Quantitative assessment of laser beam displacement during photocoagulation on patient retina using high-speed optical coherence tomography (OCT)
Author Affiliations & Notes
  • Stefan Otto Johannes Koinzer
    Ophthalmology, Kiel University, Kiel, Germany
  • Moritz C Moltmann
    Medical Laser Center Lübeck, Lübeck, Schleswig-Holstein, Germany
  • Hendrik Spahr
    Institute of Biomedical Optics, University of Luebeck, Lübeck, Germany
  • Claus von der Burchard
    Ophthalmology, Kiel University, Kiel, Germany
  • Anna Jaich
    Ophthalmology, Kiel University, Kiel, Germany
  • Konstantine Purtskhvanidze
    Ophthalmology, Kiel University, Kiel, Germany
  • Dirk Theisen-Kunde
    Medical Laser Center Lübeck, Lübeck, Schleswig-Holstein, Germany
  • Johann Roider
    Ophthalmology, Kiel University, Kiel, Germany
  • Ralf Brinkmann
    Medical Laser Center Lübeck, Lübeck, Schleswig-Holstein, Germany
  • Gereon Hüttmann
    Institute of Biomedical Optics, University of Luebeck, Lübeck, Germany
  • Footnotes
    Commercial Relationships   Stefan Koinzer, None; Moritz Moltmann, None; Hendrik Spahr, None; Claus von der Burchard, None; Anna Jaich, None; Konstantine Purtskhvanidze, None; Dirk Theisen-Kunde, None; Johann Roider, None; Ralf Brinkmann, None; Gereon Hüttmann, None
  • Footnotes
    Support  BMBF Grant No.13GW0043D
Investigative Ophthalmology & Visual Science June 2017, Vol.58, 5988. doi:
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      Stefan Otto Johannes Koinzer, Moritz C Moltmann, Hendrik Spahr, Claus von der Burchard, Anna Jaich, Konstantine Purtskhvanidze, Dirk Theisen-Kunde, Johann Roider, Ralf Brinkmann, Gereon Hüttmann; Quantitative assessment of laser beam displacement during photocoagulation on patient retina using high-speed optical coherence tomography (OCT). Invest. Ophthalmol. Vis. Sci. 2017;58(8):5988.

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

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Abstract

Purpose : Reliable doseage of retinal photocoagulation depends on exact lesion application. Precision is increasingly important in non-damaging treatments where the therapeutic window shrinks. Patient and physician unsteadiness, however, blur the laser beam image on the fundus, increasing lesion diameter and decreasing irradiance in an uncontrolled manner. In this study, we quantified such movements.

Methods : We recorded B-scan videos using a slit-lamp adapted OCT at a frame rate of 3 ms. OCT videos were acquired prospectively during photocoagulation of 220 study lesions in 5 patients (irradiation diameter 300 µm, exposure time 50 or 200 ms, moderate whitening). Image displacement within the field of view was calculated to quantify two-dimensional movements in axial and horizontal directions. We determined maximal decentrations in both axis and the total distance covered in the plane.

Results : OCT recording started about 30 ms prior to photocoagulation and was continued for about 2 s. Sufficient video quality was achieved in 20 lesions with 50 ms exposure time and 25 lesions with 200 ms. Lateral/axial decentration amplitudes and total distances were [mean±SD] 46±22/26±21/75±66 µm during 50 ms irradiations and 70±30/68±49/199±78 µm during 200 ms irradiations. The corresponding values assessed during the total OCT recording time of 2157±151 ms were 246±142/259±189/3155±2375 µm.

Conclusions : Considering that visible changes in OCT of a moderate retinal lesion measure about twice the irradiation spot diameter, lateral and axial decentrations of 45-70 µm are well acceptable in our 300 µm study irradiations. Motion becomes more critical if lesion intensity decreases, irradiation spot diameter shrinks or exposure time increases. It will induce significant variation in small (50 µm) sub-visible macular lesions. While the image is relatively stationary during the irradiation itself, maximal decentrations before and afterwards are in the order of 250 µm and add up to a total distance of > 3mm. Study limitations include ignorance of vertical movements. While only OCT videos with good quality could be assessed, greater movement is expected in lesions with lower video quality.

This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.

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