Optimization of surgical protocol for laser iridotomy based on the numerical simulation of aqueous flow

Yibo Zhao; Bin Chen; Dong Li; Yibo Zhao; Bin Chen; Dong Li

doi:10.3934/mbe.2019370

Mathematical Biosciences and Engineering

2019, Volume 16, Issue 6: 7405-7420. doi: 10.3934/mbe.2019370

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Optimization of surgical protocol for laser iridotomy based on the numerical simulation of aqueous flow

State Key Laboratory of Multiphase Flow in Power Engineering, Xi’an Jiaotong University, Xi’an, Shanxi, China

Received: 30 April 2019 Accepted: 07 August 2019 Published: 14 August 2019

Primary angle-closure glaucoma (PACG) is a major cause of blindness worldwide, with a particularly high prevalence in Asian populations. Laser iridotomy (LI) has been the standard therapeutic modality for treating PACG to avoid blindness. However, the complex structure of the eyeball, the aqueous fluidity, and the limitation of detecting equipment will cause difficulty in surgery and the probability of complications. Numerical simulation was conducted to investigate aqueous humor (AH) flow under different physiological structures before and after laser surgery. When the anterior chamber depth decreases from 2.8 mm to 2.0 mm (caused by angle-closure glaucoma), the maximum velocity of natural convection is doubled, and the pressure difference between the posterior and anterior chambers increases by 20%. Therefore, a shallow anterior chamber depth is crucial for the accurate investigation of glaucoma. Pupil block sharply increases the intraocular pressure (IOP). When the gap between the lens and iris decreases from 10 μm to 0.5 μm, P between the posterior and anterior chambers is approximately 37 times higher than before, thereby damaging intraocular tissues. LI can effectively reduce the IOP caused by pupil block, but the velocity of AH after operation is 40 times the normal condition, and the increased corneal shear stress could lead to corneal damage, which can be solved by adjusting the incident angle of laser beam On the basis of the allowable angle range of surgical equipment and the effect of different incident angles on the cornea and iris, the optimum angle of laser drilling is 45°.
- primary angle-closure glaucoma,
- laser iridotomy,
- aqueous humor flow,
- numerical simulation,
- pupil block
Citation: Yibo Zhao, Bin Chen, Dong Li. Optimization of surgical protocol for laser iridotomy based on the numerical simulation of aqueous flow[J]. Mathematical Biosciences and Engineering, 2019, 16(6): 7405-7420. doi: 10.3934/mbe.2019370

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Abstract

Primary angle-closure glaucoma (PACG) is a major cause of blindness worldwide, with a particularly high prevalence in Asian populations. Laser iridotomy (LI) has been the standard therapeutic modality for treating PACG to avoid blindness. However, the complex structure of the eyeball, the aqueous fluidity, and the limitation of detecting equipment will cause difficulty in surgery and the probability of complications. Numerical simulation was conducted to investigate aqueous humor (AH) flow under different physiological structures before and after laser surgery. When the anterior chamber depth decreases from 2.8 mm to 2.0 mm (caused by angle-closure glaucoma), the maximum velocity of natural convection is doubled, and the pressure difference between the posterior and anterior chambers increases by 20%. Therefore, a shallow anterior chamber depth is crucial for the accurate investigation of glaucoma. Pupil block sharply increases the intraocular pressure (IOP). When the gap between the lens and iris decreases from 10 μm to 0.5 μm, P between the posterior and anterior chambers is approximately 37 times higher than before, thereby damaging intraocular tissues. LI can effectively reduce the IOP caused by pupil block, but the velocity of AH after operation is 40 times the normal condition, and the increased corneal shear stress could lead to corneal damage, which can be solved by adjusting the incident angle of laser beam On the basis of the allowable angle range of surgical equipment and the effect of different incident angles on the cornea and iris, the optimum angle of laser drilling is 45°.

References

[1]	S. Zhang, C. Wu, L. Liu, et al., Optical coherence tomography angiography of the peripapillary retina in primary angle-closure glaucoma, Am. J. Ophthalmol., 182 (2017), 194.
[2]	J. Sara, A. Rouzbeh and V. H. Barocas, Contribution of different anatomical and physiologic factors to iris contour and anterior chamber angle changes during pupil dilation: theoretical analysis, Invest. Ophth. Vis. Sci., 54 (2013), 2977–2984.
[3]	F. Zhang and H. Chen, Numerical investigation of laser iridotomy influence on shear stress exerted on corneal endothelial cells, J. Med. Biomech., (2016).
[4]	L. W. Schwartz and G. L. Spaeth, Argon laser iridotomy in primary angle-closure or pupillary block glaucoma, Laser. Surg. Med., 1 (2010), 153–164.
[5]	N. Satoru and M. Akira, Three-year outcome of Descemet stripping automated endothelial keratoplasty for bullous keratopathy after argon laser iridotomy, Cornea, 33 (2014), 780–784.
[6]	O. V. Danilenko and A. V. Bol'Shunov, Laser iridectomy and anatomical and functional parameters in primary angle-closure glaucoma, Vestnik Oftalmologii, 130 (2014), 54.
[7]	O. Abouali, A. Modareszadeh, A. Ghaffarieh, et al., Investigation of saccadic eye movement effects on the fluid dynamic in the anterior chamber, J. Biomech. Eng., 134 (2012), 021002.
[8]	E. H. Ooi and E. Y. K. Ng, Effects of natural convection within the anterior chamber on the ocular heat transfer, Int. J. Numer. Meth. Bio. Eng., 27 (2015), 408–423.
[9]	Y. Yasuaki, U. Toshihiko, J. Takeshi, et al., Effect of anterior chamber depth on shear stress exerted on corneal endothelial cells by altered aqueous flow after laser iridotomy, Invest. Ophth. Vis. Sci., 51 (2010), 1956.
[10]	R. Avtar and R. Srivastava, Aqueous outflow in Schlemm's canal, Appl. Math. Comput., 174 (2006), 316–328.
[11]	T. R. Crowder and V. J. Ervin, Numerical simulations of fluid pressure in the human eye, Appl. Math. Comput., 219 (2013), 11119–11133.
[12]	E. C. Huang and V. H. Barocas, Accommodative microfluctuations and iris contour, J. Vision, 6 (2006), 653.
[13]	W. Wang, X. Qian, H. Song, et al., Fluid and structure coupling analysis of the interaction between aqueous humor and iris, Biomed. Eng. Online, 15 (2016), 133.
[14]	Y. Yasuaki, U. Toshihiko, S. Katsumi, et al., Demonstration of aqueous streaming through a laser iridotomy window against the corneal endothelium, Arch. Ophthalmol., 124 (2006), 387.
[15]	J. J. Heys, V. H. Barocas and M. J. Taravella, Modeling passive mechanical interaction between aqueous humor and iris, J. Biomech. Eng., 123 (2001), 540.
[16]	H. Y. Jie, J. H. Heo, H. M. Kim, et al., Effects of Argon Laser Iridotomy on the Corneal Endothelium of Pigmented Rabbit Eyes, Korean J. Ophthalmol., 28 (2014), 76–82.
[17]	P. X. Wang, V. T. C. Koh and L. S. Chee, Laser iridotomy and the corneal endothelium: a systemic review, Acta Ophthalmol., 92 (2015), 604–616.
[18]	R. Y. Lee, K. Toshimitsu, N. Q. Cui, et al., Association between baseline angle width and induced angle opening following prophylactic laser peripheral iridotomy, Invest. Ophth. Vis. Sci., 54 (2013), 3763–3770.

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