TY - JOUR
T1 - Dynamic multi-arm radial lens stretcher
T2 - A robotic analog of the ciliary body
AU - Reilly, Matthew A.
AU - Hamilton, Paul D.
AU - Ravi, Nathan
N1 - Funding Information:
This work was supported by a merit review grant from the Department of Veterans Affairs to Dr. Nathan Ravi, awards to the Washington University Department of Ophthalmology and Visual Sciences by Research to Prevent Blindness, Inc., and the NIH (P30 EY 02687) Core grant.
PY - 2008/1
Y1 - 2008/1
N2 - We developed a dynamic lens stretching device to quantitatively determine the relationships between force, equatorial displacement, and anterior curvature. A computer-controlled four-arm lens stretcher, equipped with real-time force transducers in each arm, was designed and constructed to obtain transient force measurements during lens stretching. The force-decay spectrum was fitted with a seven-parameter viscoelastic model characterized by three time constants. A corneal topography unit was used to measure the curvature of fresh porcine lenses ex vivo and in vitro in a four-arm lens stretcher at various equatorial displacements. The lens stretcher and corneal topography unit provided detailed information regarding the behavior of the porcine lens in vitro. For all lenses, the central portion of the anterior surface flattened as zonular force increased. Force increased nonlinearly with equatorial displacement. Relaxation time constants for accommodation were 34.5 ± 12.2 ms, 310 ± 122 ms, and 12,800 ± 9490 ms. Time constants for disaccommodation were 34.9 ± 4.7 ms, 291 ± 79.1 ms, and 3400 ± 775 ms, which were not statistically different from those measured for accommodation. The lens stretcher acts as a robotic analog of the ciliary body. This device allows direct, quantitative measurement of the forces and curvature changes relevant to accommodation. However, distortions were present due to the use of only four arms.
AB - We developed a dynamic lens stretching device to quantitatively determine the relationships between force, equatorial displacement, and anterior curvature. A computer-controlled four-arm lens stretcher, equipped with real-time force transducers in each arm, was designed and constructed to obtain transient force measurements during lens stretching. The force-decay spectrum was fitted with a seven-parameter viscoelastic model characterized by three time constants. A corneal topography unit was used to measure the curvature of fresh porcine lenses ex vivo and in vitro in a four-arm lens stretcher at various equatorial displacements. The lens stretcher and corneal topography unit provided detailed information regarding the behavior of the porcine lens in vitro. For all lenses, the central portion of the anterior surface flattened as zonular force increased. Force increased nonlinearly with equatorial displacement. Relaxation time constants for accommodation were 34.5 ± 12.2 ms, 310 ± 122 ms, and 12,800 ± 9490 ms. Time constants for disaccommodation were 34.9 ± 4.7 ms, 291 ± 79.1 ms, and 3400 ± 775 ms, which were not statistically different from those measured for accommodation. The lens stretcher acts as a robotic analog of the ciliary body. This device allows direct, quantitative measurement of the forces and curvature changes relevant to accommodation. However, distortions were present due to the use of only four arms.
KW - accommodation
KW - force of accommodation
KW - lens
KW - lens curvature
KW - lens refill
KW - lens stretching
UR - http://www.scopus.com/inward/record.url?scp=36749091103&partnerID=8YFLogxK
U2 - 10.1016/j.exer.2007.10.005
DO - 10.1016/j.exer.2007.10.005
M3 - Article
C2 - 18068804
AN - SCOPUS:36749091103
SN - 0014-4835
VL - 86
SP - 157
EP - 164
JO - Experimental eye research
JF - Experimental eye research
IS - 1
ER -