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Saori Yaguchi, Hiroko Bissen-Miyajima, Keiichiro Minami, Yuka Ota, Shigeo Yaguchi; Experimental Evaluation of Lens Capsule Stability Using Capsular Tension Rings with Different Degrees of Zonular Dehiscence. Invest. Ophthalmol. Vis. Sci. 2018;59(9):2229.
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Capsular tension rings (CTRs) are used to stabilize lens capsules in cases with mild zonular instability. We evaluated the efficacy of CTRs under different degrees of zonular dehiscence in a porcine model.
We created an experimental model of zonular dehiscence using enucleated porcine eyes. To observe the ciliary body and zonule of Zinn, diathermy was performed to dissect the iris root and the iris was removed through the corneal incision. Zonular dialysis of 30°, 45°, 60°, 90°, 120°, 150°, and 180° was created by cutting the zonular fibers using diathermy. In each range of zonular dialysis, the eyes were divided into two groups, those with and without CTRs. Continuous curvilinear capsulorrhexes were created using capsular forceps, and phacoemulsification and aspiration (PEA) were performed. The CTRs were inserted into the capsular bags before PEA in the group with CTRs. We measured the anterior capsule area before zonular dehiscence was created. During PEA, we measured the area where the vitreous surface was not covered by the anterior capsule due to zonular dehiscence. We then compared the percentages of the uncovered areas, i.e., the proportion of the uncovered areas to the anterior capsules, in each range of zonular dialysis between the groups with and without CTRs. The number of eyes in which the cortex dropped into the vitreous cavity during PEA was examined.
The mean area of the anterior lens capsule was 125.3±5.8mm2. The percentages of the uncovered areas in eyes with and without CTRs were, respectively, at 30°, 0.68±0.36% and 1.12±0.34%; 45°, 2.16±0.86% and 2.70±0.89%; 60°, 2.26±0.88% and 6.62±2.56%; 90°, 4.86±1.66% and 8.74±2.54%; 120°, 8.28±5.64% and 16.84%±7.56%; 150°, 13.26±7.26% and 24.8±9.97%; and 180°, 14.41±8.01% and 31.01±13.78%. The percentages of the uncovered areas decreased significantly (p<0.05), and fluctuations in the percentages of the uncovered area decreased using CTRs in all ranges of zonular dialysis. The percentages of eyes in which the cortex drop increased from 60° among the eyes with CTRs and from 120° among the eyes without CTRs.
The lens capsules expanded with CTRs in the experimental porcine model in all degrees of zonular dialysis. The CTRs prevented the cortex from dropping between 60° and 120° of zonular dialysis.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.
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