Abstract
Abstract: :
Purpose:A variety of models have been developed to describe accommodation. One of these models is described by Lütjen-Drecoll et al. They have shown, that a decrease in flexibility of the elastic fibres located at the posterior attachment lead to a change in configuration with a shift of the vector between the zonules and the lens. In initial eye model studies we have shown that with a special designed ring placed in the sulcus cliiaris the vector will be changed. These changes should result in an increase of accommodation. The aim of this study was to proove this concept in an animal model. We have used the Yucatan minipig as an animal model because the minipigs anatomical conditions of the anterior chamber, the lens and the sulcus are very similar to the human situation. We also have found, that this species has an accommodation and the range of accommodation decreases with age. Methods:The surgery was performed in 3 Yucatan minipigs. The Anneau Presbytie was implanted through a clear cornea incision into the sulcus ciliaris. The surgery and the postop follow-up was without any complications. The distance and near refraction was determined pre- and 1, 2, and 3 months postop after pharmaceutical stimulation by retinoscopy. From these measurements we have calculated the range of accommodation. The animals were killed after 3 months and the enucleated eyes were histologically investigated. Results:In all three animals the range of accommodation was preop between 1.00 and 1.50 D. After the implantation of the Anneau Presbytie the range of accommodation increased between 3.50 and 4.50 D. The histological investigations showed that the ring was placed in the sulcus ciliaris and that no damage to the lens or the zonulae had occurred due to the surgery. Conclusion:We have shown, that the Anneau Presbytie can improve the range of accommodation.
Keywords: 304 accommodation • 544 refractive surgery • 316 animal model