TY - JOUR
T1 - Seeing the hidden lamina
T2 - Effects of exsanguination on the optic nerve
AU - Tran, Head Huong
AU - Wallace, Jacob
AU - Zhu, Ziyi
AU - Lucy, Katie A.
AU - Voorhees, Andrew P.
AU - Schmitt, Samantha E.
AU - Bilonick, Richard A.
AU - Schuman, Joel S.
AU - Smith, Matthew A.
AU - Wollstein, Gadi
AU - Sigal, Ian A.
N1 - Funding Information:
Supported by National Institutes of Health (R01EY025011, R01EY03966, T32-EY017271, R01-EY013178, P30-EY008098, and R01EY022928), Glaucoma Research Foundation Shaffer Grant, and Eye and Ear Foundation of Pittsburgh (PA, USA).
Publisher Copyright:
© 2018 The Authors.
PY - 2018/5
Y1 - 2018/5
N2 - PURPOSE. To introduce an experimental approach for direct comparison of the primate optic nerve head (ONH) before and after death by exsanguination. METHOD. The ONHs of four eyes from three monkeys were imaged with spectral-domain optical coherence tomography (OCT) before and after exsanguination under controlled IOP. ONH structures, including the Bruch membrane (BM), BM opening, inner limiting membrane (ILM), and anterior lamina cribrosa (ALC) were delineated on 18 virtual radial sections per OCT scan. Thirteen parameters were analyzed: scleral canal at BM opening (area, planarity, and aspect ratio), ILM depth, BM depth; ALC (depth, shape index, and curvedness), and ALC visibility (globally, superior, inferior, nasal, and temporal quadrants). RESULTS. All four ALC quadrants had a statistically significant improvement in visibility after exsanguination (overall P < 0.001). ALC visibility increased by 35% globally and by 36%, 37%, 14%, and 4% in the superior, inferior, nasal, and temporal quadrants, respectively. ALC increased 4.1%, 1.9%, and 0.1% in curvedness, shape index, and depth, respectively. Scleral canals increased 7.2%, 25.2%, and 1.1% in area, planarity, and aspect ratio, respectively. ILM and BM depths averaged −7.5% and −55.2% decreases in depth, respectively. Most, but not all, changes were beyond the repeatability range. CONCLUSIONS. Exsanguination allows for improved lamina characterization, especially in regions typically blocked by shadowing in OCT. The results also demonstrate changes in ONH morphology due to the loss of blood pressure. Future research will be needed to determine whether there are differences in ONH biomechanics before and after exsanguination and what those differences would imply.
AB - PURPOSE. To introduce an experimental approach for direct comparison of the primate optic nerve head (ONH) before and after death by exsanguination. METHOD. The ONHs of four eyes from three monkeys were imaged with spectral-domain optical coherence tomography (OCT) before and after exsanguination under controlled IOP. ONH structures, including the Bruch membrane (BM), BM opening, inner limiting membrane (ILM), and anterior lamina cribrosa (ALC) were delineated on 18 virtual radial sections per OCT scan. Thirteen parameters were analyzed: scleral canal at BM opening (area, planarity, and aspect ratio), ILM depth, BM depth; ALC (depth, shape index, and curvedness), and ALC visibility (globally, superior, inferior, nasal, and temporal quadrants). RESULTS. All four ALC quadrants had a statistically significant improvement in visibility after exsanguination (overall P < 0.001). ALC visibility increased by 35% globally and by 36%, 37%, 14%, and 4% in the superior, inferior, nasal, and temporal quadrants, respectively. ALC increased 4.1%, 1.9%, and 0.1% in curvedness, shape index, and depth, respectively. Scleral canals increased 7.2%, 25.2%, and 1.1% in area, planarity, and aspect ratio, respectively. ILM and BM depths averaged −7.5% and −55.2% decreases in depth, respectively. Most, but not all, changes were beyond the repeatability range. CONCLUSIONS. Exsanguination allows for improved lamina characterization, especially in regions typically blocked by shadowing in OCT. The results also demonstrate changes in ONH morphology due to the loss of blood pressure. Future research will be needed to determine whether there are differences in ONH biomechanics before and after exsanguination and what those differences would imply.
KW - Blood vessel shadow
KW - Exsanguination
KW - Lamina cribrosa
KW - OCT
KW - Optic nerve head
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U2 - 10.1167/iovs.17-23356
DO - 10.1167/iovs.17-23356
M3 - Article
C2 - 29847664
AN - SCOPUS:85047839668
SN - 0146-0404
VL - 59
SP - 2564
EP - 2575
JO - Investigative Ophthalmology and Visual Science
JF - Investigative Ophthalmology and Visual Science
IS - 6
ER -