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Biomedical subjects

K Tsubota

Publications and source records attributed to K Tsubota.

At least 181 records · Page 10Linked to original sources
PubMed1995

Sodium hyaluronate eyedrops in the treatment of dry eyes.

BACKGROUND: Several studies in the past have attempted to demonstrate the efficacy of sodium hyaluronate in the treatment of dry eyes. However, results have been conflicting and a definite conclusion has not yet been reached. This study recruited a larger group of patients and has incorporated for the first time both fluorescein and rose bengal staining in the evaluation of the epithelium. METHODS: Eighteen albino rabbit corneas were used in a basic animal study to demonstrate the efficacy of sodium hyaluronate by comparing the effects on the rate of epithelial healing. The optimal concentration to be used in the clinical trial was determined from the results of the basic study. In the clinical study 104 patients with dry eye syndrome were enrolled in a double masked controlled clinical trial. Patients received sodium hyaluronate drops in one eye and control medication in the other eye for 4 weeks. Grading of subjective symptoms and clinical examinations were performed at 2 and 4 weeks. RESULTS: In the animal study sodium hyaluronate at concentrations of 0.1% and 0.5% significantly accelerated the recovery time of iodine vapour induced corneal erosions (p < 0.01). In the clinical study no statistical significance was observed in the improvement of subjective symptoms or rose bengal staining, while fluorescein scores significantly improved in eyes receiving sodium hyaluronate (p = 0.0001) at 4 weeks. CONCLUSION: Sodium hyaluronate drops applied in six daily doses could not be demonstrated to offer advantages over conventional tear supplies in the improvement of subjective symptoms, but may play a role in maintaining a healthy corneal epithelium.

Animals↗
PubMed1995

Correlation of tear clearance rate and fluorophotometric assessment of tear turnover.

BACKGROUND: The study sought to determine dynamic changes and theoretical bases of a clinical diagnostic test, the tear clearance rate. METHODS: Thirty four healthy subjects ranging in age from 22 to 84 years underwent examination of tear clearance rate, the Schirmer test with anaesthesia, as well as fluorophotometric measurement of tear turnover, tear volume, and tear flow. By applying 0.5% fluorescein into the conjunctival sac and subsequently measuring colour fades on a Schirmer strip, the tear clearance rate for assessing tear drainage was divided into nine grades. The results of the tear clearance rate were compared with those of the basal tear turnover and tear flow obtained from fluorophotometry. RESULTS: Significant relations were found between the tear clearance rate and the basal tear turnover or tear flow (r = 0.91 and 0.79, respectively, p = 0.0001). Considering the grades of progression from low to high, each grade of tear clearance rate showed a 12.5% increase in basal tear turnover (3.59%/min) and tear flow (0.38 microliter/min). There was no significant correlation between age and the basal tear turnover, tear volume, tear flow, or the tear clearance rate. CONCLUSION: The tear clearance rate is proposed as a simple and useful way to estimate basal tear turnover and tear flow, and measure tear drainage indirectly.

Adult↗
PubMed1995

Corneal epithelium following penetrating keratoplasty.

AIMS: This study was designed to observe any changes to the corneal epithelium after penetrating keratoplasty. METHODS: The corneal epithelia of 26 patients were observed by specular microscopy 1 week, 1 month, 3 months, and 6 months following penetrating keratoplasty. RESULTS: After re-epithelialisation was confirmed by biomicroscopy 1 week after surgery, specular microscopy revealed many abnormal cells, including spindle shaped cells, nucleated cells, large cells, as well as irregular cell configurations. Although these abnormal findings tended to decrease with time, they were still present in some cases as much as 6 months postoperatively. Computerised morphometric analysis yielded mean cell areas of 1121 (SD 168) microns 2, 1139 (675) microns 2, 1712 (496) microns 2, and 1400 (377) microns 2 at 1 week, 1 month, 3 months, and 6 months respectively, all significantly greater than that of age matched controls (710 (151) microns 2). The shape factor decreased with time, but was still greater than the control level at 6 months. CONCLUSIONS: This study demonstrates that epithelial abnormalities persist longer than expected after penetrating keratoplasty, and that these subtle changes can be detected by specular microscopic observation, potentially allowing for modification and enhancement of the wound healing process.

Adolescent↗
PubMed1995

A case of one eye with gelatinous drop-like corneal dystrophy and the other eye with band-shaped spheroidal corneal degeneration.

The first case of gelatinous drop-like corneal dystrophy in one eye and band-shaped spheroidal corneal degeneration in the other eye was reported. She was a member of Japanese family with gelatinous drop-like corneal dystrophy. A close association between gelatinous drop-like corneal dystrophy and band-shaped spheroidal corneal degeneration was suggested.

Adult↗
PubMed1995

Direct sub-Tenon's ocular anesthesia for strabismus surgery.

We assessed the safety and effectiveness of sub-Tenon's anesthesia, a local anesthesia, for strabismus surgery. For 15 surgeries, we used anesthesia by sub-Tenon's infusion, followed by direct infusion through a transconjunctival route with a local anesthetic agent. We found the procedure was simple, it minimized complications compared with other techniques and was effective in achieving rapid anesthesia. With the ocular movement remaining, we checked eye position by the alternative cover-uncover test at the end of surgery. We obtained good eye position for all patients. This method leads to good results for strabismus surgery.

Adolescent↗
PubMed1995

[The effects of stellate ganglion block on conjunctival oxygen tension and intraocular pressure in patients with retinal vein occlusion].

We evaluated the effects of stellate ganglion block (SGB) on conjunctival oxygen tension, ocular surface temperature (n = 7) and intraocular pressure (n = 18) in patients with retinal vein occlusion and other retinopathy. The conjunctival oxygen tension (PcjO2) increased from 45.6 +/- 5.0 mmHg to 76.3 +/- 19.9 mmHg in 45 minutes by SGB and then gradually returned to the control level. PcjO2 120 minutes following SGB remained still at a higher level compared with the control value. Ocular surface temperature increased from 35.1 +/- 0.3 degrees C to 35.9 +/- 0.3 degrees C 25 minutes following SGB. Intraocular pressure decreased below the control level from 15 minutes to 120 minutes by SGB following an initial temporary increase. In conclusion, we have found that SGB does increase oxygen tension in ocular tissue and decrease IOP.

Adult↗
PubMed1995

Corneal epithelium in keratoconus.

Specular microscopy was employed to study the corneal epithelium of 20 keratoconus patients (17 male, 3 female, average age 23.9 +/- 6.6 years). The patients were divided into three groups based on the severity of the keratoconus; early, intermediate, and advanced. Initially, epithelial changes were limited to enlargement of the superficial cells. As the disease progressed, elongated cells became prominent. Irregularly configurated and nucleated epithelial cells were observed in all cases. Morphomeric analysis showed that the mean area of the corneal epithelial cells was 906 +/- 203 microns 2 in the early stage, 1,416 +/- 521 microns 2 in the intermediate stage, and 1,641 +/- 372 microns 2 in the advanced stage. The shape factor was 0.32 +/- 0.05, 0.76 +/- 0.22, and 0.81 +/- 0.17, respectively. Controls were chronic wearers of hard contact lenses without corneal pathology. Analysis of their epithelium revealed no abnormalities. This finding suggests that the epithelial changes observed in keratoconus are not due to the wearing of contact lenses, but rather to the disease itself.

Adolescent↗
PubMed1995

Changes of corneal redox state in diabetic animal models.

Metabolic and biochemical changes of the corneal epithelium and endothelium were studied in experimental diabetic animal models. Ocular redox fluorometry was used to noninvasively determine tissue reduction-oxidation (redox) changes in organ cultured rabbit corneas incubated in high glucose concentration media, alloxan-induced diabetic rabbits, and nonobese diabetic mice. The ratio of autofluorescence from reduced pyridine nucleotide to oxidized flavoproteins (PN/Fp) was used as the indicator of the redox state. Chemical assays for NADH and NAD+ were performed on in vitro materials. Analysis of corneal endothelial morphology using specular microscopy was performed to study possible correlations with metabolic changes. Both the PN/Fp and NADH/NAD+ ratios increased in the corneal endothelium under all experimental conditions. Changes in redox state were not observed in the corneal epithelium in any of the models. Morphologic analysis of the corneal endothelium revealed no significant changes. These results indicate that redox changes occur in the diabetic corneal endothelium, but not the corneal epithelium. Ocular redox fluorometry is capable of detecting changes in the corneal endothelial redox state noninvasively.

Animals↗
PubMed1995

[Usefulness of the DNA-HLA class II typing in corneal transplantation].

DNA-HLA (human leukocyte antigen) typing was performed for ocular tissues in order to determine the usefulness of the method in corneal transplantation. Each type of ocular tissue was dissected from eye bank eyes (n = 3). DNA was extracted, and HLA-DRB1, DQB1, and DPB1 genes were amplified using PCR (polymerase chain reaction) method. DNA can be extracted and amplified from each ocular tissue except for the crystalline lens, but DNA from iris and choroid can be amplified only after diluting the samples 10 to 100 times. HLA class II antigens were successfully determined in these ocular tissues by the RFLP (restriction fragment length polymorphism) method. The method was applied to the corneal tissues of donor and recipient used for the corneal transplantation (n = 7). HLA class II antigens can be determined in both the donor and recipient corneal samples, and the results of recipients' HLA typing were the same as those determined using the blood samples. These results indicate that the DNA-HLA typing can be used for ocular tissues. Since DNA-HLA typing is more accurate than the conventional serological typing, the method is promising for the study of HLA class II typing in corneal transplantation.

Aged↗
PubMed1995

Persistent epithelial defect following penetrating keratoplasty: an adverse effect of diclofenac eyedrops.

Association between the use of diclofenac sodium (DfNa) eyedrops and the development of a postkeratoplasty persistent epithelial defect (PED) of the cornea were studied. In 100 consecutive patients undergoing penetrating keratoplasty who had no limbal or conjunctival epithelial abnormalities, 12 (12.0%) developed PED (persistence of epithelial defect for > 8 days after keratoplasty) postoperatively. The use of DfNa eyedrops correlated significantly with the development of PED (p = 0.0001, chi-square test). DfNa eyedrops were used in 19 eyes postoperatively, eight of which (42.1%) showed signs of PED. The type of preservation media, preservation time, indications for keratoplasty, or the surgical procedures performed did not correlate with the development of PED. These results indicate that DfNa eyedrops are toxic to the corneal epithelium postkeratoplasty. The eyedrops should be used with great care in patients with disorders of the corneal epithelium.

Adult↗
PubMed1995

Allergic conjunctivitis caused by sugi (Cryptomeria japonica D. Don) pollen out of season.

Allergic conjunctivitis caused by sugi pollen is considered to be strictly a "spring disease". However, a recent report indicated that sugi pollen is scattered not only in spring but in all seasons, especially in the autumn. We retrospectively determined the number of patients with allergic conjunctivitis caused by sugi pollen during each month for 3 consecutive years, and also investigated the growth of sugi male cones in November for four years. Diagnosis of allergic conjunctivitis was based on symptomatic complaints, clinical findings, and serum sugi pollen specific IgE measured by the Multiple Antigen Simultaneous Test 16. The annual incidence of allergic conjunctivitis peaked twice, once in spring and again in autumn. Scattering of sugi pollen occurred mostly in March and October, whilst the growth of sugi male cones was highest in November. Thus, allergy to sugi pollen can cause allergic conjunctivitis both in the spring and late autumn.

Adolescent↗
PubMed1994

Specular microscopic evaluation of the corneal epithelium after excimer laser photorefractive keratectomy.

Nineteen eyes underwent photorefractive keratectomy to correct myopia. Using the specular microscope, we observed the central corneal epithelium of each eye preoperatively and at one, three, and six months after surgery. A normal epithelial pattern was observed in 18 eyes (94.7%) at one and three months and in 19 eyes (100%) at six months after surgery. There was no statistically significant difference in the pre- and postoperative mean cell area and corresponding coefficient of variation. These results suggest that the destruction of Bowman's layer produced by photorefractive keratectomy does not affect the morphologic characteristics of the most superficial layer of the corneal epithelium.

Adult↗