Biomedical subjects
Publications and source records attributed to M Ayaki.
I performed an anterior capsulectomy in six eyes using an ordinary phacoemulsification (phaco) tip. The technique, which involves inserting a beveled-down phaco tip directly into the lens, created smooth and tear-free capsular openings. Although the procedure needs to be refined, I believe a phaco tip can be used effectively and easily to remove the anterior capsule.
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Using a scanning electron microscope, we studied the surface structure of 5 different central nuclei, isolated by repeated hydrodissection during extracapsular cataract extraction. Aside from the damage induced by surgical maneuvers, the surfaces were very smooth, and there was no major disruption of the lamellar structure of the lens. Our studies have shown that hydrodissection, which allows atraumatic separation of the lens fiber layers, can be used to analyze the lamellar structure of the lens. Some of the evaluated specimens showed a distinct suture line and the lens fibers were approximately at right angles to it. These observations were different from those reported previously.
We measured the diameter and central thickness of the central nucleus, isolated by repeated hydrodissection, in 100 eyes undergoing extracapsular cataract extraction. The average diameter and central thickness were 6.43 +/- 0.86 mm and 2.93 +/- 0.36 mm, respectively. The average ratio between the two measurements was 2.12, which is similar to that of an extracted crystalline lens. Statistical analysis revealed a positive correlation between central thickness and age (p < 0.05). There was a weak positive correlation between central thickness and hardness of the nucleus. Since specimens were obtained from clinical cases in this study, further evaluation should be made using cadaver eyes.
We measured the extracted central nucleus (diameter and thickness) of 88 eyes (average patient age, 72 years) undergoing extracapsular cataract extraction (ECCE). The average diameter was 6.51 +/- 0.75 mm; the average thickness, 2.96 +/- 0.33 mm. Since the average lens diameter is approximately 10 mm, a corneoscleral incision of 7 to 8 mm in chord length should be sufficient for its removal in most ECCE cases. Accumulation of these data and further analysis correlating them with age and degree and type of cataract in larger series will be useful in determining the smallest possible incision size required for individual patients.
The authors performed a histopathological study to observe the surface of IOLs placed inside the capsular bag of white rabbit eyes. While a cellular reaction to the haptics was indicated by lens epithelial cells and collagen fibers surrounding the haptics, a wound healing reaction at the anterior capsule-optic junctions was suggested by an extensive amount of spindle cells and collagen fibers. However, collagen fibers and degenerated cells on the optics could be seen only under electron microscopy. Regenerated lens fibers, lens epithelial cells, and proliferation of spindle cells were noted between the posterior side of the optics and the posterior capsules.
We performed light microscopic studies of after-cataract formation after phacoemulsification and out-of-the-bag IOL implantation in 23 rabbit eyes. One day after, epithelial cells at the equatorial area began to move to the pupillary area of the posterior capsule. A week later, we saw adhesion of the anterior capsular edge to the central posterior capsule with newly-formed lens fibers in the capsular space. These findings were similar to after-cataract formation after phacoemulsification only. We found no apparent effect of IOL on after-cataract formation when it was fixed out of the bag.
Sequential changes in the lens capsules of the rabbit eye after phacoemulsification with in-the-bag fixation of IOL were studied light microscopically. There were three types of after-cataract. Two of them, in which the anterior capsular flap contacted the posterior capsule and/or the anterior surface of the optics of IOL, were similar to that in aphakic cases. The other type, in which the anterior capsular edge contacted the IOL only, showed a number of characteristic findings. The capsular space was closed with a residual lens capsule and IOL optics, and typical Soemmerring's ring was observed there. Fibrous proliferation was observed at the anterior capsular edge, not on the posterior capsule. Lens epithelia on the posterior capsule moved beneath the IOL and reproduced new lens fibers.
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