Correlation Between Biomechanical Responses of Posterior Sclera and IOP Elevations During Micro Intraocular Volume Change

Morris, Hugh J.; Tang, Junhua; Perez, Benjamin Cruz; Pan, Xueliang; Hart, Richard T.; Weber, Paul A.; Liu, Jun

doi:10.1167/iovs.13-12441

Cited by 46 publications

(56 citation statements)

References 47 publications

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“…Furthermore, formalin fixation (as performed on human eye globes for pathological assessment) may influence tissue rigidity [36], which could have a direct impact on the IOP induced by externally applied forces. In contrast, several studies have shown that porcine eye globes have mechanical and geometric properties similar to human eye globes so that our results should be comparable to human eyes [29,[37][38][39][40]. Our results also affect clinical settings.…”

Section: Discussioncontrasting

confidence: 50%

Short-Term Intraocular Pressure Rise during Locally Induced Force by Ophthalmologic Surgery Applications

et al. 2018

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Purpose: Surgical or diagnostic procedures are often accompanied by a short-term increase in intraocular pressure (IOP). A short-term increase in IOP can occur during refractive procedures, vitreoretinal surgery, transillumination, photocoagulation, or cryocoagulation. A porcine eye model was chosen (n = 89) to compile comparable study data and to de termine correlations between the force induced and the resulting intraocular pressure while excluding the effect of surgeons. Methods: The IOP was measured in the anterior chamber. IOP changes were induced by applying an external force and measured when using a cannula, trocar, and cryocoagulation (n = 32), and correlations between force and resulting IOP were assessed (n = 57). Results: A correlation was noted between the force induced and the IOP increase, which showed a linear dependency. The insertion of a 29-G cannula caused a mean ΔIOP value of 49.1 ± 2.9 mm Hg and an external force of 0.76 N, and that of a 23-G trocar 344.4 ± 5.9 mm Hg and 6.09 N, respectively. The rise in IOP during a simulated cryocoagulation reached values between 57.3 ± 14.8 mm Hg (cryoprobe tip diameter: 0.9 mm) and 130.3 ± 2.9 mm Hg (cryoprobe tip diameter: 7.0 mm). Conclusion: The values of the forces applied can be converted into the resulting IOP based on the specific action. Surgical or diagnostic procedures should, therefore, be evaluated with regard to preexisting pathologies, such as glaucoma.

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Section: Discussioncontrasting

confidence: 50%

Short-Term Intraocular Pressure Rise during Locally Induced Force by Ophthalmologic Surgery Applications

et al. 2018

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“…41 Stiffening of the scleral shell leads to greater high-frequency IOP fluctuations. 18,42 A growing body of research has shown that the sclera becomes stiffer in glaucoma. 7,43,44 These latter findings would support a link between myofibroblast-mediated detrimental sclera remodeling and mechanical damage to the ONH.…”

Section: Discussionmentioning

confidence: 99%

High-Magnitude and/or High-Frequency Mechanical Strain Promotes Peripapillary Scleral Myofibroblast Differentiation

Zhu

Ambalavanan

et al. 2015

Invest. Ophthalmol. Vis. Sci.

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PURPOSE.To determine the effects of altered mechanical strain on human peripapillary scleral (ppSc) fibroblast-to-myofibroblast differentiation.METHODS. Eight human ppSc fibroblast cultures were isolated from three paired eyes and two unilateral eyes of five donors using an explant approach. Human ppSc fibroblast isolates were subjected to 1% and 4% cyclic strain at 0.05 to 5 Hz for 24 hours. Levels of a smooth muscle actin (aSMA) mRNA and protein were determined by real-time PCR and immunoblot. Incorporation of aSMA into actin stress fibers was evaluated by confocal immunofluorescent microscopy. Myofibroblast contractility was measured by fibroblast-populated three-dimensional collagen gel contraction assay and phosphorylation of myosin light chain (MLC 20 ).RESULTS. Human ppSc fibroblasts contained 6% to 47% fully differentiated myofibroblasts before strain application; 4% cyclic strain increased aSMA mRNA and protein expression in ppSc fibroblasts compared with 1% strain applied at 5 Hz, but not at lower frequencies. Seven of eight ppSc fibroblast isolates responded to high-magnitude and high-frequency strain with increased cellular contractility and increased MLC 20 phosphorylation. In addition, increasing strain frequency promoted aSMA expression in ppSc fibroblasts under both 1% and 4% strain conditions.CONCLUSIONS. High-magnitude and/or high-frequency mechanical strain promotes differentiation of human ppSc fibroblasts into contractile myofibroblasts, a fibroblast phenotypic change known to be key to tissue injury-repair responses. These findings suggest that the cellular constituent of ppSc may play an important role in the regulation of optic nerve head biomechanics in response to injurious IOP fluctuations.

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“…Several reports have suggested a link between AL, refractive error and IOP increase following injection,15–17 but others have found evidence to the contrary 18. Although injection volumes are generally small (of the order of 0.05 mL), a recent study on postmortem porcine globes demonstrated increases in IOP of approximately 15 mm Hg following 1 s 15 mL (0.015 mL) microinfusions of phosphate buffered saline 19. A clinical research application of this study could be, therefore, to examine whether ocular volume is a structural correlate for IOP change following intravitreal injections.…”

Section: Discussionmentioning

confidence: 99%

Estimation of ocular volume from axial length

2014

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Correlation Between Biomechanical Responses of Posterior Sclera and IOP Elevations During Micro Intraocular Volume Change

Cited by 46 publications

References 47 publications

Short-Term Intraocular Pressure Rise during Locally Induced Force by Ophthalmologic Surgery Applications

Short-Term Intraocular Pressure Rise during Locally Induced Force by Ophthalmologic Surgery Applications

High-Magnitude and/or High-Frequency Mechanical Strain Promotes Peripapillary Scleral Myofibroblast Differentiation

Estimation of ocular volume from axial length

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