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Presented by A. Rismanchian MD Farabi Hospital

Clinical Aspects Of OPTICAL COHERENCE TOMOGRAPHY IN GLAUCOMA. Presented by A. Rismanchian MD Farabi Hospital. Optical coherence tomography (OCT; Zeiss-Humphrey). Introduced in 1991 Provides high-resolution cross-sectional imaging of the retina and the NFL.

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Presented by A. Rismanchian MD Farabi Hospital

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  1. Clinical Aspects Of OPTICAL COHERENCE TOMOGRAPHY IN GLAUCOMA Presented by A. Rismanchian MD Farabi Hospital

  2. Optical coherence tomography (OCT; Zeiss-Humphrey) • Introduced in 1991 • Provides high-resolution cross-sectional imaging of the retina and the NFL. • Is analogous to ultrasound B-scan imaging. • A short coherence length diode source (850 nm).

  3. Resolution • Conventional ultrasound: 150 mic • UBM 20 mic (penetration depth of 4 mm) • CTS and MRI several hundred mic • OCT I, II : 12-15 mic • OCT III : 8-10 mic • Ultra- High resolution OCT : 2-3 mic

  4. The operation of OCT is based on the principle of low coherence interferometry

  5. Light is directed onto a partially reflecting mirror and is split into reference and measurement beams.

  6. The measurement beam is reflected from the eye with minutely different time delays depending on its internal microstructure..

  7. The light in the reference beam is reflected from the mirror at a variable distance that produces a variable but known time delay.

  8. The light from the eye, consisting of multiple echoes, and the light from the reference mirror, consisting of a single echo with a known delay are combined and detected.

  9. When the two light beams coincide, they produce a phenomenon known as interference, which is measured by a photodetector.

  10. Tissues with high reflectivity => white or red (RPE, NFL) Those with low reflectivity => blue or green (choroid, gang cells, photoreceptors) No reflectivity : black ( vitreous) Retina - Histology Ganglion Cell INL Nerve fiber layer ONL (PR) Retinal Pigment Epithelium (RPE) IPL- OPL- PR OS- Choroid -Chorio- capillaris -Large choroidal vessels

  11. Retina - Histology RNFL Ganglion Cell Bodies Photo Receptors RPE

  12. OCT3 Images In previous OCT images, we were able to see four layers of the retina. Now we are seeing 7, or sometimes 8.

  13. OCT3 Images We Now Believe That the Best Way to View OCT3 Images is in the B & W Mode. It Appears to Give More Details.

  14. Types of measurment in Glaucoma • NFL thickness in the peripapillary region circular (3.4mm) linear tomogram • Optic nerve head profile • Macular volume (has a reverse correlation with glaucoma damage)

  15. Other Clinical applications • Corneal thickness (Hoerauf et al. 2000) • Anterior chamber depth (Hoerauf et al. 2000) for the diagnosis of angle closure glaucoma. • Iris thickness and profile (Hoerauf et al. 2000), potentially useful for plateau iris, pigment dispersion and angle closure glaucoma.

  16. NFL thickness

  17. Retinal Nerve FiberLayer Analysis Circular scans of 3.4 mm measures RNFL in the peripapillary region

  18. Stratus OCT PrintoutRNFL Thickness Average Analysis RNFL 3.4 mm

  19. Patient information scan information

  20. Fundus Image • To verify scan placement.

  21. ضمن عرض پوزش بدلیل حجم بالای LECTUER ادامه اسلایدها امکان پذیر نمیباشد در صورت نیاز به ادامه لطفا به واحد سمعی و بصری مرکز آموزشی درمانی فیض مراجعه و یا با شماره تلفن 03114476010 داخلی 392تماس حاصل نمائید با تشکر

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