Biomedical subjects
Publications and source records attributed to N S Rice.
We produced experimental immune reactions by exchanging peripheral corneal transplants between rabbits. Clobetasone butyrate 0.1% and dexamethasone phosphate 0.1% eye drops were equally effective in delaying corneal allograft rejection.
Corneal graft survival in rabbits was significantly (P less than 0 . 001) prolonged by topical treatment to the recipient eye with cyclosporin A 1% in arachis oil applied five times daily for 4 weeks. No graft was rejected whilst treatment was maintained but all grafts subsequently underwent rejection by the 64th postoperative day. All animals in a simultaneous control group in this fully masked study developed allograft reactions by the 23rd day. No local or systemic side-effects attributable to cyclosporin A were observed. It is believed that this is the first report of inhibition of an allograft reaction by cyclosporin A applied topically.
One hundred thirty-two penetrating keratoplasties (91 patients) for herpetic keratoplasty were reviewed retrospectively. The overall survival rate of clear keratoplasties to two years was 64% and to five years was 62%. The significant prognostic factors were preoperative ocular inflammatory status and degree of corneal vascularization. The two-year survival rate of a clear keratoplasty was 69% where eyes were inflamed at the time of surgery, compared with 44% in actively inflamed eyes. Allograft rejection, the major cause of a clouded herpetic keratoplasty, increased in frequency with increasing corneal vascularization. Antiviral cover was not used with routine postoperative steroids or with steroid intensive therapy for rejection. Epithelial herpetic recurrences occurred in 32% of eyes undergoing allograft rejection within four months of initiation of treatment for rejection. This is compared with otherwise uncomplicated keratoplasties where the epithelial recurrence rate was 6% at four months, on high-dose postoperative corticosteroid therapy without antiviral cover.
Cyclosporin A given to rabbits intramuscularly in a dose of 25 mg/kg/day for up to 28 days after corneal transfer results in a marked prolongation in the survival of penetrating corneal grafts compared to that in an untreated control group. Cyclosporin A 1% drops did not prolong survival of the corneal graft, but this may be related to the need for skin transfer 14 days after corneal transfer to ensure rejection, and supports the idea that the drug plays an immunosuppressive role at the time and place of sensitisation.
This paper reports the occurrence of retinal detachment in 18 patients suffering from congenital glaucoma. Difficulty in establishing control of the glaucoma and the presence of high myopia were common findings. The poor results of detachment surgery were related to opacites in the media preventing evaluation of the renal details and the development of massive preretinal retraction.
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The endothelium of the normal corneas of 67 human subjects was studied in vivo with the specular microscope in order to quantify the method as a means of sampling the cell density of the tissue. It was found that (1) axial cell counts of the endothelium are reproducible in the same cornea after an interval of time; (2) the cell counts of the centre and periphery of the same cornea are similar; (3) the axial cell counts of pairs of eyes are similar; and (4) there is a gradual reduction of cell number with increasing age. The significance of these data is discussed.
The ultrasonic radiation utilised in phacoemulsification procedures for the removal of cataractous lenses results in the widespread production of discrete lesions in the corneal endothelium. The morphology of this induced damage has been examined in rabbit and man using both scanning and transmission electron microscopy. The illustrated results are related to both the duration of the ultrasonic exposure and to the mechanisms of damage.
The responses of corneal endothelium to a 2-minute exposure of ultrasound from a clinical phacoemulsification device have been studied by specular microscopy and both scanning and transmission electron microscope. Healing of lesions occurred in two ways, and these were related to lesion size. Small lesions healed by a process of rosette formation, and large lesions were repaired by a process of endothelial dedifferentiation and migration. All damaged areas were re-covered with endothelial cells within 24 hours of exposure, and at this time corneal thickness had returned to control levels. The implications are discussed in relation to the phacoemulsification procedure.
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We present our evaluation of the McCarey-Kaufman (M-K) method of corneal storage. Sixty-six rabbit corneas were stored in the M-K medium at 4 C for periods of four, eight, and 12 days. Endothelial viability was assessed, using the specular microscope, the phenomenon of temperature reversal, and known inhibitors of endothelial cell function. Our results support those of McCarey and Kaufman, who showed that rabbit corneas will remain viable when stored by this technique. We were unable to support the contention that M-K medium-stored corneas are functionally superior to those corneas stored in moist chambers in the conventional manner. An unsuccessful attempt was made to correlate the function of the endothelium with either its morphological appearance as seen through the specular microscope or changes in ultrastructure as shown by transmission electron microscopy.
The endothelial function of rabbit corneas stored in modified tissue culture medium (McCarey-Kaufman medium) for periods of 4, 8, or 12 days was studied after penetrating keratoplasty using the specular microscope and the response to temperature reversal. Our results indicate that rabbit donor corneas stored in McCarey-Kaufman (M-K) medium are suitable for penetrating keratoplasty after storage periods as long as 12 days. The limitations of using graft clarity or the morphologic appearance of the endothelium as an index of the success of a penetrating keratoplasty in the rabbit are discussed.
A case of reduplication of the lens with uveal coloboma is described. This is a rare condition and, unlike the two previously reported cases, the other ocular structures and adnexae appeared normal.
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We used the photodynamic inactivation technique with proflavine as the photoactive dye to treat herpetic epithelial keratitis in a preliminary study of patients who had idoxuridine toxicity or resistance. A comparative study with idoxuridine in treating dendritic ulcerations of the cornea showed a good therapeutic effect. But the investigation was suspended when adverse reactions, consisting of a generalized epithelial keratitis and an anterior uveitis, possibly of phototoxic origin, developed in a few patients receiving treatment. The ulcers treated by photodynamic inactivation apparently healed by a process of "debridement" followed by subsequent re-epithelialization.
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