TY - JOUR
T1 - The Strain Response to Intraocular Pressure Decrease in the Lamina Cribrosa of Patients with Glaucoma
AU - Czerpak, Cameron A.
AU - Kashaf, Michael Saheb
AU - Zimmerman, Brandon K.
AU - Quigley, Harry A.
AU - Nguyen, Thao D.
N1 - Funding Information:
Funded in part by NIH NEI R01 02120 (H.A.Q.), P30 01765 (Wilmer Institute Core Grant), Research to Prevent Blindness , the A. Edward Maumenee Professorship (to H.A.Q.), and BrightFocus .
Funding Information:
Funded in part by NIH NEI R01 02120 (H.A.Q.), P30 01765 (Wilmer Institute Core Grant), Research to Prevent Blindness, the A. Edward Maumenee Professorship (to H.A.Q.), and BrightFocus. Obtained funding: Quigley, Nguyen; Study was performed as part of regular employment duties at Johns Hopkins University. No additional funding was provided.
Publisher Copyright:
© 2022 American Academy of Ophthalmology
PY - 2023/1/1
Y1 - 2023/1/1
N2 - Objective: To measure biomechanical strains in the lamina cribrosa (LC) of living human eyes with intraocular pressure (IOP) lowering. Design: Cohort study. Participants: Patients with glaucoma underwent imaging before and after laser suturelysis after trabeculectomy surgery (29 image pairs; 26 persons). Intervention: Noninvasive imaging of the eye. Main Outcome Measures: Strains in optic nerve head tissue and changes in depths of the anterior border of the LC. Results: Intraocular pressure decreases caused the LC to expand in thickness in the anterior-posterior strain (Ezz = 0.94 ± 1.2%; P = 0.00020) and contract in radius in the radial strain (Err = − 0.19 ± 0.33%; P = 0.0043). The mean LC depth did not significantly change with IOP lowering (1.33 ± 6.26 μm; P = 0.26). A larger IOP decrease produced a larger, more tensile Ezz (P < 0.0001), greater maximum principal strain (Emax; P < 0.0001), and greater maximum shear strain (Γmax; P < 0.0001). The average LC depth change was associated with the Γmax and radial-circumferential shear strain (Erθ; P < 0.02) but was not significantly related to tensile or compressive strains. An analysis by clock hour showed that in temporal clock hours 3 to 6, a more anterior LC movement was associated with a more positive Emax, and in clock hours 3, 5, and 6, it was associated with a more positive Γmax. At 10 o'clock, a more posterior LC movement was related to a more positive Emax (P < 0.004). Greater compliance (strain/ΔIOP) of Emax (P = 0.044), Γmax (P = 0.052), and Erθ (P = 0.018) was associated with a thinner retinal nerve fiber layer. Greater compliance of Emax (P = 0.041), Γmax (P = 0.021), Erθ (P = 0.024), and in-plane shear strain (Erz; P = 0.0069) was associated with more negative mean deviations. Greater compliance of Γmax (P = 0.055), Erθ (P = 0.040), and Erz (P = 0.015) was associated with lower visual field indices. Conclusions: With IOP lowering, the LC moves either into or out of the eye but, on average, expands in thickness and contracts in radius. Shear strains are nearly as substantial as in-plane strains. Biomechanical strains are more compliant in eyes with greater glaucoma damage. This work was registered at ClinicalTrials.gov as NCT03267849.
AB - Objective: To measure biomechanical strains in the lamina cribrosa (LC) of living human eyes with intraocular pressure (IOP) lowering. Design: Cohort study. Participants: Patients with glaucoma underwent imaging before and after laser suturelysis after trabeculectomy surgery (29 image pairs; 26 persons). Intervention: Noninvasive imaging of the eye. Main Outcome Measures: Strains in optic nerve head tissue and changes in depths of the anterior border of the LC. Results: Intraocular pressure decreases caused the LC to expand in thickness in the anterior-posterior strain (Ezz = 0.94 ± 1.2%; P = 0.00020) and contract in radius in the radial strain (Err = − 0.19 ± 0.33%; P = 0.0043). The mean LC depth did not significantly change with IOP lowering (1.33 ± 6.26 μm; P = 0.26). A larger IOP decrease produced a larger, more tensile Ezz (P < 0.0001), greater maximum principal strain (Emax; P < 0.0001), and greater maximum shear strain (Γmax; P < 0.0001). The average LC depth change was associated with the Γmax and radial-circumferential shear strain (Erθ; P < 0.02) but was not significantly related to tensile or compressive strains. An analysis by clock hour showed that in temporal clock hours 3 to 6, a more anterior LC movement was associated with a more positive Emax, and in clock hours 3, 5, and 6, it was associated with a more positive Γmax. At 10 o'clock, a more posterior LC movement was related to a more positive Emax (P < 0.004). Greater compliance (strain/ΔIOP) of Emax (P = 0.044), Γmax (P = 0.052), and Erθ (P = 0.018) was associated with a thinner retinal nerve fiber layer. Greater compliance of Emax (P = 0.041), Γmax (P = 0.021), Erθ (P = 0.024), and in-plane shear strain (Erz; P = 0.0069) was associated with more negative mean deviations. Greater compliance of Γmax (P = 0.055), Erθ (P = 0.040), and Erz (P = 0.015) was associated with lower visual field indices. Conclusions: With IOP lowering, the LC moves either into or out of the eye but, on average, expands in thickness and contracts in radius. Shear strains are nearly as substantial as in-plane strains. Biomechanical strains are more compliant in eyes with greater glaucoma damage. This work was registered at ClinicalTrials.gov as NCT03267849.
KW - Digital volume correlation
KW - Glaucoma
KW - Intraocular pressure
KW - Optic nerve head
KW - Strain
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U2 - 10.1016/j.ogla.2022.07.005
DO - 10.1016/j.ogla.2022.07.005
M3 - Article
C2 - 35863747
AN - SCOPUS:85138175208
SN - 2589-4234
VL - 6
SP - 11
EP - 22
JO - Ophthalmology. Glaucoma
JF - Ophthalmology. Glaucoma
IS - 1
ER -