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Biomedical subjects

M Sawa

Publications and source records attributed to M Sawa.

At least 127 records · Page 7Linked to original sources
PubMed1988

Posterior chamber lens implantation and anterior segment barrier function: a fluorophotometric study.

We used fluorophotometry and pachymetry to examine the early postoperative effects on the anterior segment of the eye after posterior chamber intraocular lens implantation combined with extracapsular cataract extraction as compared to extra-capsular cataract extraction alone. Fluorophotometry was performed by a method of intravenous injection of fluorescein solution (1 mg/kg of body weight) on the 6th postoperative day. We calculated the value of the Fa/Fp ratio, where Fa and Fp were fluorescein concentration in the aqueous and the plasma ultrafiltrate, respectively, and treated it as an index of the blood-aqueous barrier function. Also, we optically measured the corneal thickness and the anterior chamber depth. There were no significant differences between the values of the Fa/Fp ratio and corneal thickness in the two groups. The anterior chamber depth in the pseudophakic eyes (2.89 +/- 0.48 mm, mean +/- SD) differed significantly from that of the eyes undergoing extracapsular cataract extraction alone (3.10 +/- 0.51, P less than 0.001). In the cases of posterior chamber lens implantation, the postoperative value of the Fa/Fp ratio in the intact fellow eyes showed a significant increase compared to the preoperative value in the same eyes (1.2 +/- 0.8 times, P less than 0.05). We conclude that the effects on the anterior segment barrier function of extracapsular lens extraction followed by posterior chamber intraocular lens implantation are not significantly different from those of extracapsular lens extraction alone.

Aged↗
PubMed1987

A new method for obtaining biomicroscopic photographs of the vitreous.

We describe a new method for obtaining photographs of the vitreous in vivo using an automatic-exposure photo-slitlamp microscope in combination with a high-speed color-reversal film and a Goldmann-type contact lens. Using our method, we investigated the microscopic characteristics of various vitreoretinal disorders. The patients studied comprised four cases with rhegmatogenous retinal detachments and one case with the sudden onset of vitreous floaters with posterior vitreous detachment (PVD). Our technique enabled us to obtain detailed images of vitreoretinal relationships, and to obtain a clearer understanding of vitreoretinal disorders than has been provided by previous methods. We conclude that our method is useful for clinical investigations of various vitreoretinal disorders.

Adult↗
PubMed1987

Human corneal endothelial permeability to fluorescein and fluorescein glucuronide.

The corneal endothelial permeability coefficient (Pac) for fluorescein and fluorescein glucuronide was determined in ten normal young volunteers. After oral administration of fluorescein, the apparent concentrations of both dyes in the corneal stroma and the anterior chamber were measured by differential fluorometry. The apparent dye levels calculated directly from the in vivo fluorometric measurements were converted to the true ones, based on the result of a normalization experiment performed in rabbit eyes. The value of Pac averaged 5.44 +/- 1.77 X 10(-4) cm/min for fluorescein and 3.77 +/- 1.10 X 10(-4) cm/min for fluorescein glucuronide (mean +/- SD, N = 20); the former was significantly greater than the latter (paired t-test, P less than 0.001). The aqueous-cornea distribution ratio was 0.50 +/- 0.14 for fluorescein and 0.66 +/- 0.16 for fluorescein glucuronide; the latter was significantly greater than the former (paired t-test, P less than 0.001). It was suggested that the previously reported values of Pac for fluorescein in the human eye were underestimates.

Administration, Oral↗
PubMed1986

Aqueous to cornea fluorescein distribution ratio in normal and swollen cornea.

Intravitreal sodium fluorescein was used to simulate equilibrium fluorescein kinetics, thereby allowing simple measurement of the aqueous to cornea fluorescein distribution ratio. Two groups of rabbit corneas were studied: normal corneas and corneas wounded by freezing. The aqueous to cornea fluorescein distribution ratio was approximately 0.4, was not significantly different in groups of normal or wounded eyes and little variability was noted. In addition, a comparison of in vivo and in vitro measurements of corneal fluorescein concentration in wounded eyes suggests that in vivo protein-bound fluorescein in the cornea fluoresces less efficiently than free fluorescein.

Animals↗
PubMed1986

Cryopreservation of fetal rat liver tissue--a morphological investigation.

The present study was undertaken to define optimal conditions for cryopreservation of fetal rat liver tissue fragments. First, various cooling rates (1, 4, 10, 20 and 30 degrees C/min) and preserving temperatures (-20, -80 and -196 degrees C) were examined. Next, various concentrations of Me2SO (5, 10, 20 and 30 per cent vol/vol) were examined by freezing at a rate of 4 degrees C/min to -80 degrees C before transfer to -196 degrees C. All samples were preserved for at least one week. After recovery from cryopreservation, the fragments were transplanted into the spleens of syngeneic rats. Histological assessment of the grafts was made one month after transplantation. Consequently, the optimal cryopreserving conditions for fetal rat liver fragments were defined as follows: cooling rate was 1 to 10 degrees C/min, preserving temperature was at -196 degrees C, concentration of Me2SO was 20 per cent (final concentration: 10 per cent). In the long term observation, the stored liver fragments could be differentiated into adult hepatocytes and the surviving hepatocytes showed little difference from the nonfrozen controls, either histochemically or ultrastructurally. The surviving hepatocytes in the stored transplants were less numerous than in the nonfrozen ones and hepatic cell plates and sinusoids were nil.

Animals↗
PubMed1986

Treatment of superior limbic keratoconjunctivitis by thermocauterization of the superior bulbar conjunctiva.

Superior limbic keratoconjunctivitis (SLK) is a chronic and recurrent inflammatory disease of the superior tarsal, bulbar and limbal conjunctiva that often responds to topical treatment with silver nitrate. As an alternative treatment in 11 patients (13 eyes), we applied thermal cautery to the inflamed superior bulbar conjunctiva following subconjunctival injection of 2% xylocaine. The overall positive response rate to thermocautery was 73% (8 patients). Of the positive responders, 63% (5 patients) had been considered silver nitrate treatment failures. Keratitis sicca was additionally noted in 55% of the patients studied. Impression cytology of involved superior bulbar conjunctiva was nearly devoid of goblet cells during the acute stage of the disorder. Following successful cauterization, goblet cells returned. Thus, thermocauterization of the superior bulbar conjunctiva appears to be a safe and effective mode of therapy for SLK.

Adult↗
PubMed1985

Cellular migration and morphology in corneal endothelial wound repair.

After a mechanical denudation of rabbit corneal endothelial cells, the healing process was followed with wide-field specular microscopy. Individual cell migration and morphologic changes were analyzed by computer-assisted morphometry. The cells surrounding the wound migrated to cover the defect without producing intercellular gaps. The greatest cellular migration and morphologic alterations occurred close to the wound edge. As the cells migrated toward the wound, they elongated and increased their surface area in the direction of the migration. As the healing proceeded, the cells lost their original hexagonal pattern, which returned after coverage was complete. The wound was covered completely by large, irregularly shaped cells showing mitotic figures between 24 and 48 hr. During this period, cellular migration decreased and normal cellular morphology began to recover. When mitosis decreased, the normal cellular pattern rearranged towards a more hexagonal shape. During the healing process, the degree and direction of cellular migration varied from cell to cell. Additionally, changes in cell-to-cell contact (positional changes of neighboring cells) occurred in one-third of migrating cells. Such cellular migration can account for monolayered cells sliding without producing gaps between individual cells.

Animals↗
PubMed1984

Fluorophotometric study of anterior segment barrier functions after extracapsular cataract extraction and posterior chamber intraocular lens implantation.

We used fluorophotometry and pachymetry to examine the longer-term (more than three months) postoperative effects in the anterior segment of extracapsular lens extraction with and without posterior chamber intraocular lens implantation. Fluorophotometry was performed after oral administration of fluorescein solution (5 mg/kg of body weight under fasting condition). We calculated the corneal endothelial transfer coefficient, fluorescein distribution ratio, aqueous transfer coefficient in reference to chamber volume, and loss coefficient and measured corneal thickness with a modified pachymeter. There were no significant differences between the values for corneal endothelial transfer coefficient and corneal thickness in the two groups of surgically treated eyes combined vs the intact fellow eyes. The aqueous transfer coefficient and loss coefficient values were not significantly different between the two surgically treated groups. Anterior chamber depth did not differ significantly between the two surgical groups, but the value for the two groups combined (3.79 mm) did differ significantly from that of the fellow eyes (2.87 mm) (P less than .005). We concluded that endothelial function recovers three months after extracapsular lens extraction with or without posterior chamber intraocular lens implantation, and that the effects of intraocular lens implantation on anterior segment barrier functions are not significantly different from those of extracapsular lens extraction alone.

Adult↗
PubMed1984

Clinical classification of after-cataract following planned extracapsular cataract extraction.

A total of 100 eyes underwent planned extracapsular cataract extraction and were followed more than three months with a mean follow-up period of 12 +/- 8 months. After-cataract was found in 72 eyes. The after-cataract was classified by slit-lamp microscopy into two types, the remnant type and the proliferative type. The former type was due to remains of the lens materials and was present immediately after the surgery: this type was divided into veil-like and Soemmering forms. The proliferative type developed after a period following surgery and was divided into fibrous form and Elschnig form. The fibrous form was thought to be due to fibrous proliferation of the lens epithelial cells, since it was seen at or to originate from the sites of adhesion of the anterior and posterior capsules. The Elschnig form consisted of Elschnig's pearls and was divided into progressive and localized subforms. The former subform was seen more frequently in young patients than the latter subform. The incidences of the above types and forms of the after-cataract were determined. Impairment of the visual acuity due to after-cataract was seen in the proliferative type and was found in 7 eyes. A fluorophotometric study to evaluate the function of the blood-aqueous barrier was carried out in 7 patients with the presence of after-cataract and in 11 patients with no or subtle after-cataract. No difference was found in the barrier function between the two groups.

Adolescent↗