Arun Narayanaswamy1, Mui Hoon Nai2, Monisha E Nongpiur1,3, Hla Myint Htoon1,3, Anoop Thomas4, Tiakumzuk Sangtam4, Chwee Teck Lim2,5,6, Tina T Wong1,3, Tin Aung1,3,7. 1. Singapore Eye Research Institute and Singapore National Eye Center, Singapore. 2. Department of Biomedical Engineering, National University of Singapore, Singapore. 3. Duke-NUS Graduate Medical School, Singapore. 4. Department of Ophthalmology & Visual Sciences Khoo Teck Puat Hospital, Singapore. 5. Mechanobiology Institute, National University of Singapore, Singapore. 6. Biomedical Institute for Global Health Research and Technology, National University of Singapore, Singapore. 7. Yong Loo Lin School of Medicine, National University of Singapore, Singapore.
Abstract
Purpose: To evaluate the biomechanical properties (Young's modulus) of normal (control) and glaucomatous human iris using atomic force microscopy (AFM). Methods: Iris tissue obtained from eighteen glaucomatous subjects (equal number of eyes with primary angle closure glaucoma (PACG) and primary open angle glaucoma (POAG) and five normal subjects who underwent elective eye surgery were subjected to the estimation of Young's modulus by AFM. Force measurements were done at room temperature using Nanowizard II BioAFM. The iris samples were immersed in the liquid media (PBS with 0.1% BSA) during force measurements. Young's modulus values were calculated for each recorded curve using JPK Data Processing Software, which uses a Hertz's contact model for spherical indenters fitted to the extend curves. Results: The iris from the normal controls had the least Young's modulus (0.85 ± 0.31 kPa) while those from PACG patients had the highest Young's modulus (2.40 ± 0.82 kPa). The Young's modulus of PACG iris was significantly higher compared to that of the normal controls (P = 0.005) and POAG iris (P = 0.001). However, there was no significant difference in the Young's modulus of POAG iris (1.13 ± 0.36 kPa) compared to that of the normal controls (P = 0.511). Conclusions: Variations in biomechanical properties of iris tissue may have a significant role in the pathogenesis of angle closure glaucoma. This study suggests the existence of fundamental biomechanical differences in eyes with angle closure versus open angle glaucoma. An understanding of this basis creates a new platform to understand disease pathology better and work on therapeutic strategies that will address the same.
Purpose: To evaluate the biomechanical properties (Young's modulus) of normal (control) and glaucomatous human iris using atomic force microscopy (AFM). Methods: Iris tissue obtained from eighteen glaucomatous subjects (equal number of eyes with primary angle closure glaucoma (PACG) and primary open angle glaucoma (POAG) and five normal subjects who underwent elective eye surgery were subjected to the estimation of Young's modulus by AFM. Force measurements were done at room temperature using Nanowizard II BioAFM. The iris samples were immersed in the liquid media (PBS with 0.1% BSA) during force measurements. Young's modulus values were calculated for each recorded curve using JPK Data Processing Software, which uses a Hertz's contact model for spherical indenters fitted to the extend curves. Results: The iris from the normal controls had the least Young's modulus (0.85 ± 0.31 kPa) while those from PACG patients had the highest Young's modulus (2.40 ± 0.82 kPa). The Young's modulus of PACG iris was significantly higher compared to that of the normal controls (P = 0.005) and POAG iris (P = 0.001). However, there was no significant difference in the Young's modulus of POAG iris (1.13 ± 0.36 kPa) compared to that of the normal controls (P = 0.511). Conclusions: Variations in biomechanical properties of iris tissue may have a significant role in the pathogenesis of angle closure glaucoma. This study suggests the existence of fundamental biomechanical differences in eyes with angle closure versus open angle glaucoma. An understanding of this basis creates a new platform to understand disease pathology better and work on therapeutic strategies that will address the same.
Authors: J K Wenderott; Carmen G Flesher; Nicki A Baker; Christopher K Neeley; Oliver A Varban; Carey N Lumeng; Lutfiyya N Muhammad; Chen Yeh; Peter F Green; Robert W O'Rourke Journal: Sci Rep Date: 2020-11-24 Impact factor: 4.379
Authors: Olivia S Huang; Li-Fong Seet; Henrietta W Ho; Stephanie W Chu; Arun Narayanaswamy; Shamira A Perera; Rahat Husain; Tin Aung; Tina T Wong Journal: Invest Ophthalmol Vis Sci Date: 2021-02-01 Impact factor: 4.799