Simple fixation and storage protocol for preserving the internal structure of intact human donor lenses and extracted human nuclear cataract specimens.
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PURPOSE: Increased use of phacoemulsification procedures for cataract surgeries has resulted in a dramatic decrease in the availability of cataractous nuclear specimens for basic research into the mechanism of human cataract formation. To overcome such difficulties, a fixation protocol was developed to provide good initial fixation of human donor lenses and extracted nuclei, when available, and is suitable for storing or shipping cataracts to laboratories where structural studies could be completed. METHODS: Cataractous lens nuclei (n=19, ages 12 to 74 years) were obtained from operating suites after extracapsular extraction. Transparent human donor lenses (n=27, ages 22 to 92 years) were obtained from the Ramayamma International Eye Bank. After the dimensions were measured with a digital caliper, samples were preserved in 10% formalin (neutral buffered) for 24 h and followed by fixation in 4% paraformaldehyde (pH 7.2) for 48 h. Samples were stored cold (4 degrees C) in buffer until shipped. Samples were photographed and measured before further processing for transmission electron microscopy. RESULTS: The dimensions of the samples varied slightly after short fixation followed by 1 to 5 months' storage before transmission electron microscopy processing. The mean change in the axial thickness of the donor lenses was 0.15+/-0.21 mm or 3.0+/-5.4%, while that of the extracted nuclei was 0.05+/-0.24 mm or 1.8+/-7.6%. Because the initial concern was whether the nuclear core was preserved, thin sections were examined from the embryonic and fetal nuclear regions. All cellular structures were preserved, including the cytoplasm, complex edge processes, membranes, and junctions. The preservation quality was excellent and nearly equivalent to preservation of fresh lenses even for the lens cortex. Cell damage characteristic of specific nuclear cataract types was easily recognized. CONCLUSIONS: The novel fixation protocol appears effective in preserving whole donor lenses and cataractous nuclei over a wide age range. Dimensions varied only 2%-3%, and fiber cell damage correlated well with standard fixation. These methods enable researchers and clinicians in remote settings to preserve donor lenses and rare examples of extracapsular extractions for detailed examination at later times. (+info)
The grave necessity to make eye bank specular microscopy mandatory in all eye banks in the subcontinent to improve utilization of scarce donor corneas.
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Effectiveness of a decontamination method for donor corneas.
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A retrospective study was made of the effectiveness of an eye bank decontamination and storage method. A comparison was made between microbial cultures taken from the limbus at enucleation and from scleral remnants recovered after surgery. Organisms were isolated from the limbus of 73% of donor eyes and from 4% of remnants. Standard eye bank procedures were found to eradicate gut and skin organisms, including candida, from donor tissue. (+info)
In vitro specular microscope perfusion of M-K- and moist chamber-stored human corneas.
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Human donor corneas were stored in McCarey-Kaufman (M-K) medium for 3 to 6 days; then they were mounted in the specular microscope, and the endothelial surface perfused with a glutathione-bicarbonate-Ringer solution. During storage, the corneal thickness increased 37% above an assumed normal of 0.520 mm. The corneas did not have sufficient active thinning to be accepted as viable when tested by the temperature-reversal phenomenon. Since comparable donor corneas have been used in successful penetrating keratoplasties, there must be a discrepancy between the cell viability as tested by the temperature-reversal phenomenon and clinical application. (+info)
Na,K-ATPase in simulated eye bank and cryoextracted rabbit lenses, and human eye bank lenses and cataracts.
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In the rabbit, cryoextraction of the lens and subsequent storage in Tyrode's solution did not alter the Na,K-ATPase activity from that determined in immediately excised rabbit lenses. Similarly, the procedures employed with the rabbit eye to simulate collection and storage of normal human eyes (eye banking) had no effect upon the Na,K-ATPase activity of the lens. These results permitted the investigation of human lenses with the knowledge that measured Na,K-ATPase activity had not been altered grossly by any manipulation procedures. Analysis of Na,K-ATPase activity in 44 eye bank lenses, 14 primary nuclear cataracts, 11 primary cortical cataracts, 18 primary posterior subcapsular cataracts, and 31 mixed cataracts revealed no significant difference in the enzyme activity between these groups. Similarly, there was no correlation between electrolyte levels and Na,K-ATPase in a further 18 mixed cataracts. It is concluded that, despite an often pronounced electrolyte imbalance, human cataract can develop without significant alteration in Na,K-ATPase activity. (+info)
Human vitreous transplantation.
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This lecture presents the experience in 200 implantations of human eye-bank vitreous through the pars plana of eyes with complicated retinal detachments. Though the success rate was modest, it shows that a large-bore instrument can be passed into the vitreous cavity of the eye with relative impunity and sets the stage for the present popular machine vitrectomy. In addition, the paper presents the author's experience with human vitreous transplantation by the 'open sky' transcorneal technique for otherwise hopeless vitreous opacities. (+info)