[Attempt to the measurement of the tension of zonular fibers--influence to the lens suspensory apparatus when the lens was vertically displaced by pushing posteriorly].

A new fine pressure gauge was developed to quantitate zonular tension of the albino rabbit eye. This apparatus consists of a plastic rod to press the crystalline lens, transducer, amplifier, and recorder. The diameter of this plastic rod is 8 mm. The cornea and the iris of enucleated eyes were removed by excision in the limbus. Afterwards the lens were vertically pressed by the plastic rod of the fine pressure transducer. It was necessary to disrupt a part of zonules by approximately 106 g (2.11 g/mm2). This result was equivalent to 155 mmHg. The morphological changes of the anterior part of eye globe which consists of lens, zonules, and ciliary process were investigated using scanning electron microscopy. In the control eyes, the zonular fibers mostly originated from the superior or lateral ciliary processes and inserted straight into the equatorial region of the lens. In comparison with control eyes, the zonular fibers which were pressed by the plastic rod were almost absent within 1/6 of a circle. This disruption occurred at the region adjacent to the ciliary e process, while the region of the insertion to the lens demonstrated a normal appearance. In the unaffected area zonules were well-preserved morphologically, apart from splits of the bundles of zonules. The present study indicated that zonular fibers could resist a stretching press up to approximately 8 times normal intraocular pressure.