1,2Lohmann C. P., 1Winkler von Mohrenfels C. W., 3Bos G., 2Marshall J.

1Universitäts-Augenklinik Regensburg; 2Dept of Ophthalmology, The Rayne Institute, ST Thomas' Hospital London; 3Societe Medicale de Precision, Genf

Background: A variety of models have been developed to describe accommodation. One of those models are described by Lütjen-Drecoll et al. They have shown, that a decrease in flexibility of the elastic fibres 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 sulcus ring the zonules will pushed backwards and subsequently both the tension of the zonules and 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 minipig the anatomical conditions of the anterior chamber, the lens and the sulcus are similar to the human situation. We also have found, that this species has an accommodation and the range of accommodation decreases with age.
Material and Methods: The surgery was performed in 3 Yucatan minipigs. The sulcusring was implanted through a clear cornea incision into the sulcus ciliaris. The surgery and the postop follow-up was without any complications (no lens damage, no increase of intraocular pressure, no iris damage). The distance and near refraction was determined pre- and after 7 days after pharmaceutical stimulation by retinoscopy and from these measurements we have calculated the range of accommodation. The animals were killed after 7 days and the enucliated eyes were histologically investigated.
Results: In all three animals the range of accommodation was preoperatively between 1.00 and 1.50 D. After the implantation of the sulcus ring the range of accommodation increased between 3.5 and 4.5 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.
Conclusions: We have shown, that the sulcus ring can improve the range of accommodation. Currently, we are performing more animal experiments, which should show that the effect is stable over a longer time period and if the sulcus ring induces cataract or glaucoma.

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