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Biomedical subjects

S Shirato

Publications and source records attributed to S Shirato.

At least 55 records · Page 3Linked to original sources
PubMed1992

[Subjective detection of visual field defects using the noise-field on a home TV set in low-tension glaucoma].

The usefulness of the Noise-Field Test was studied in 196 normal eyes and 146 eyes of low-tension glaucoma patients (including 74 eyes of early glaucoma) who had never perceived their filed defects. The noise-field spontaneously generated on a 21-inch home television screen through a non-transmitting channel was utilized for the test. A white mark 5 mm in diameter was stuck on the center of the screen as a fixation point. At a distance of 30 cm, the subjects were asked to watch the screen, gazing at the fixation point with one eye for 3-5 seconds, checking to see whether the flickering area on the noise-field diminished or disappeared. The test was performed 3 times on each eye. In 136 glaucoma eyes, the field defects detected by static perimetry (Humphrey) were clearly identified in the Noise-Field Test. In normal eyes, a scotoma was noted on the blind spot in 6 eyes, The sensitivity and specificity was 93.2% and 96.9%, respectively. The Noise-Field Test can be an excellent method in screening for low-tension glaucoma which is easily missed by tonometric screening only.

Adult↗
PubMed1991

Subjective detection of visual field defects using home TV set.

The usefulness of the noise-field spontaneously generated on a home television screen for subjective perception of visual field defects was studied in 196 eyes of ocular hypertensive or normal subjects, 166 eyes with primary open angle glaucoma and 124 eyes with low-tension glaucoma. All subjects had never perceived their field defects. In 290 glaucoma eyes, including 71 eyes of early glaucoma, 265 eyes (91.4%) could perceive abnormality of the noise-field which corresponded to visual field defects confirmed by static perimetry. In 6 normal eyes abnormality of the noise-field was perceived at the blind spot. The sensitivity and specificity of the test was 91% and 97%, respectively. The time required for testing one eye was 3-5 seconds. The results indicate that the Noise-Field Test using a home television set can be an excellent method for subjective perception of visual field defects, and can also be used for glaucoma screening.

Fundus Oculi↗
PubMed1991

[Diurnal variation of intraocular pressure in low tension glaucoma].

Around-the clock intraocular pressure (IOP) measurement were performed in 104 eyes of 52 low tension glaucoma (LTG) cases. Subjects were all hospitalized and IOP measurements were done every 2 hours from 6:00 AM to 12:00 PM and every 3 hours from 12:00 PM to 6:00 AM. All LTG patients met the following criteria, (1) glaucomatous optic nerve head change and corresponding visual field defect, (2) normal open angle, (3) IOP less than or equal to 21mmHg at any time of IOP measurement, (4) no obvious neurological or rhinological disorders that could affect the optic nerve, (5) no history of hemodynamic crisis or cardiovascular disorders except mild hypertension. Peak IOPs were most frequently observed at 10:00 AM, but about 55% of all observed peaks were in the time period from 6:00 PM to 8:00 AM. Most troughs were observed from 2:00 PM to 10:00 PM. The mean IOP, the diurnal variation and the difference between both eyes in the same person averaged 14.1, 4.9, and 0.6mmHg, respectively. Assuming that the period of rhythm is 24 hours, the results of IOP measurements fitted a cosine curve using the least square method. In 44% of all eyes, significant correlation coefficient (r greater than or equal to 0.6, p less than 0.05) between the measured and the predicted IOPs was noted, and an equation, IOP = 14.3 + 1.7cos 2 pi (t/24-0.4 radian), was obtained. Comparing the present results with former ones, we concluded that the IOP changes in LTG patients were similar to those in normal individuals.

Circadian Rhythm↗
PubMed1991

[Internal sclerostomy with a high-powered argon laser].

A full-thickness sclerostomy from the anterior chamber to the subconjunctival space was created in 9 eyes of 7 rhesus monkeys using an argon endolaser. After the injection of sodium hyaluronate into the subconjunctival space and the anterior chamber, a 300 microns fiberoptic fiber coupled with an argon laser (HGM, model 20) was inserted to the anterior chamber and positioned at the trabecular meshwork. A patent sclerostomy was created in all 9 eyes by 1 to 3 laser pulses with an energy of 4W with a duration of 0.5 second. Preoperative intraocular pressure in treated eyes and untreated eyes, measured with a pneumatic tonometer, was the same. After one month, the intraocular pressure of the treated eyes was 4.6 +/- 0.4mmHg lower than that of the untreated eyes. Histologic study revealed that the sclerostomies with a diameter of 200-300 microns from the anterior chamber opening to the subconjunctival space were patent at one month after the treatment. Internal sclerostomy with a high powered argon endolaser may hold potential as a new filtering procedure which can easily be performed with a minimum of conjunctival damage.

Animals↗
PubMed1990

Internal sclerostomy with argon contact laser--animal experiment using 5-fluorouracil.

A full-thickness sclerostomy was carried out with an ab interno approach, using an argon endolaser, in 9 eyes of 7 rhesus monkeys. After the injection of sodium hyaluronate into the subconjunctival space and the anterior chamber, a 300 micron fiber optic probe coupled with a water-cooled argon laser was inserted into the anterior chamber through the corneal incision made by a 23-gauge needle and positioned on the trabecular meshwork opposite to the corneal incision. A patent sclerostomy was obtained in all 9 eyes by 1 to 3 laser pulses with an energy of 4 W and a pulse duration of 0.5 seconds. After the surgery, 0.1 ml of 5-fluorouracil was injected subconjunctivally every day for one week. Intraocular pressure (IOP) was determined by pneumatic tonometer for one month at appropriate intervals. Mean preoperative IOP was 22 mmHg in both operated and nonoperated eyes. After one month IOP was 4.6 +/- 0.4 mmHg lower in the operated eyes than in the nonoperated eyes. Histologic study revealed that the sclerostomies from the anterior chamber opening to the subconjunctival space with the diameter of 200-300 microns still remained patent one month after surgery. Ab interno sclerostomy with an argon endolaser would be useful as a new filtering procedure which can easily be performed with minimum conjunctival damage.

Animals↗
PubMed1990

[The influence of the intraocular pressure on the visual field of low tension glaucoma].

To study the effect of the intraocular pressure (IOP) on the visual field (VF) damage in low tension glaucoma (LTG), we compared the IOP and the VF damage in both eyes of 46 LTG patients. As an index of the VF damage, we used the mean deviation (MD) value calculated by the Humphry (30-2) STATPAC program, and for the IOP data, the mean of 24 hour IOP measurements (diurnal IOP) and the mean of the IOPs measured at each visit to our outpatient clinics (follow-up IOP). In 13 cases, the diurnal and the follow-up IOPs were 0.3 mmHg higher or more in the more damaged eye than those in the less damaged eye, and in 7 cases they were 0.3 mmHg higher or more in the less damaged eye than those in the more damaged eye. Between these two groups, no significant difference was seen in the value of MD, but the diurnal IOP and the follow-up IOP was significantly higher in the former than in the latter group. By discrimination analysis, the two groups were distinguished at the diurnal IOP of 14.1 mmHg (hit rate 77.6%) and the follow-up IOP of 15.0 mmHg (74.2%). An analysis using the whole 46 LTG cases yielded the following results: when the diurnal or follow-up IOP of the more damaged eye was higher than the above determined level, the IOP in the more damaged eye was significantly higher than that in the contralateral less damaged eye.(ABSTRACT TRUNCATED AT 250 WORDS)

Aged↗
PubMed1989

Effect of postoperative subconjunctival 5-fluorouracil injections on the surgical outcome of trabeculectomy in the Japanese.

A controlled study was carried out to evaluate the effect of postoperative subconjunctival 5-fluorouracil (5-FU) injections on the surgical outcomes of trabeculectomy in the Japanese (a total of 196 eyes in 157 patients). The eyes that had undergone trabeculectomy with postoperative 5-FU (5-FU group) included 36 eyes with primary open-angle glaucoma (POAG) and 17 with secondary glaucoma (SG) undergoing their first or second trabeculectomy. There were also 34 eyes with refractory glaucoma. The eyes that had had trabeculectomy without postoperative 5-FU (control group) included 46 POAG and 31 SG eyes undergoing their first or second trabeculectomy and 24 refractory glaucoma eyes. The surgical techniques and postoperative care were virtually identical between the two groups, except that the control group did not receive 5-FU. The results were analyzed by means of a life table method and a postoperative intraocular pressure (IOP) level equal to or less than 20 mmHg was adopted as the criterion for successful IOP control. In the 5-FU group, the success probability (%) at the 3-year follow-up was 93.9 +/- 4.2 (SE) for POAG eyes, 93.8 +/- 6.1 for SG eyes, and 86.7 +/- 5.6 for refractory glaucoma eyes. In the control group, it was 55.0 +/- 7.9, 37.2 +/- 13.5, and 16.1 +/- 7.4, respectively. The difference in success probability between the 5-FU and control groups was highly significant (P less than 0.001 or 0.01). In the POAG and SG eyes, the mean postoperative IOP was significantly lower in the 5-FU group than in the control group.(ABSTRACT TRUNCATED AT 250 WORDS)

Adolescent↗
PubMed1989

Kinetics of phagocytosis in trabecular meshwork cells. Flow cytometry and morphometry.

Confluent human trabecular meshwork (HTM) cells from three different donors and at various stages of serial passage were fed fluorescein-labeled polystyrene beads. Phagocytosis was monitored for up to 6 days using flow cytometry, fluorescence microscopy, and morphometric calculations from comprehensive electron microscopic observations at key time points. During the first 4 hr after initiation of phagocytosis, the confluent endothelial monolayer lost its cohesiveness and became segregated into separate cells. During the first 3 days the cells underwent marked and progressive changes in shape and size. After 4 days, some cells detached from the dish, as necrotic debris and degenerative changes appeared. The kinetics of phagocytosis in this stable, confluent monolayer showed that recruitment (the percentage of cells which had ingested at least one bead) proceeded semilogarithmically, with 50% of the cells recruited by 8 hr and 97% by 96 hr. The time course of phagocytosis (ie, the average number of beads phagocytosed per cell) is described by a sigmoidlike curve, reaching half-maximum at 40 hr and maximum (about 500 beads per cell) at 96 hr. The rate of uptake (ie, the first derivative of the average number of beads per cell) reached a peak (nine beads per cell per hr) at 24 hr and then decelerated slowly over the next 5 days. Cytochalasin B treatment, as a control, reduced phagocytosis by approximately 70%. Flow cytometry, when combined with electron microscopy, should provide a useful tool to examine phagocytosis in HTM cells exposed to steroids and other hormones and drugs.

Adult↗
PubMed1987

5-Fluorouracil for trabeculectomy in glaucoma.

The effect of 5-fluorouracil (5-FU) subconjunctival injection on the bleb formation and intraocular pressure (IOP) following trabeculectomy was studied in 18 glaucoma patients (20 eyes) with poor surgical prognosis. The results were analyzed by means of life tables and compared with those of 24 glaucoma eyes that had undergone trabeculectomy without postoperative administration of 5-FU after a previous repeat trabeculectomy that had failed. The surgical techniques and postoperative care were virtually identical between the eyes treated with 5-FU and eyes that had undergone repeat trabeculectomy, except that the latter group did not receive 5-FU postoperatively. At the end of 18-month follow-up, the success probability was 68.2% in the 5-FU treated eyes, and it was already as low as 10% in the nontreated eyes at the end of the 14-month follow-up. The difference was statistically highly significant (P less than 0.001). Postoperative, subconjunctival injection of 5-FU appears to improve the prognosis following trabeculectomy in patients with a poor surgical prognosis.

Cicatrix↗
PubMed1987

Factors affecting success and IOP rise after argon laser trabeculoplasty.

One hundred and seventeen eyes of 98 patients with open-angle glaucoma where maximum tolerable medication failed to control the intraocular pressure (IOP) were treated by argon laser trabeculoplasty. We applied multiple logistic regression analysis to the clinical data of these eyes to determine the factors which are related to the success rate and the immediate postoperative elevation of the IOP. The treatment was regarded as a success when the IOP was maintained at or below 20 mmHg during the postoperative follow-up. The treatment was judged as a failure when the IOP at two consecutive visits of the patient exceeded 20 mmHg or other surgical intervention was contemplated because of uncontrolled IOP. According to the above criteria, the success rate was found to be related to the pretreatment base line IOP, the type of glaucoma, the sex, the age and the history of previous ocular surgery. The computed logistic function could classify correctly 80% of eyes that had successful IOP control and 65% that did not. The immediate postoperative elevation of IOP was found to be related to the base line IOP, the laser power, the age and the type of glaucoma. The computed logistic function could classify correctly 74% of eyes with positive IOP rise by more than 5 mmHg and 75% with negative IOP rise.

Adult↗
PubMed1987

One-quadrant argon laser trabeculoplasty and its indication.

Argon laser trabeculoplasty (ALT) with 25 burn spots over the inferotemporal quadrant of the angle circumference was carried out in 71 eyes of 55 patients with open-angle glaucoma where maximum tolerable medication failed to control the intraocular pressure (IOP). Eighteen eyes underwent a second treatment, over the inferonasal quadrant. The overall success rate of the postoperative IOP control below 20 mmHg with continued medication was analyzed by means of a life-table method. It was 68 +/- 8% after 15 months. One-quadrant ALT gave approximately the same IOP control rate with less complications when compared to the results of the standard 180-degree ALT.

Adolescent↗
PubMed1986

Optic disc hemorrhage in low-tension glaucoma.

The prevalence of optic disc hemorrhage (DH) was determined in groups consisting of 192 primary open-angle glaucoma, 113 primary angle-closure glaucoma, 78 low-tension glaucoma, and 473 normal patients. The DH was mot prevalent (20.5%) among low tension glaucoma patients (chi 2; P less than 0.001). The epidemiological features of DH were studied in 58 low-tension glaucoma patients by examining them every one to four weeks from 6 to 32 months. All the DHs but one took place within a seven-month follow-up and the incidence of DH varies from 0 to 10% during the 32-month follow-up period. The overall incidence of DH was 24.8% during that period of time. Recurrences were seen in 64% of the eyes and 92% of these occurred within 28 weeks following the previous hemorrhages. Ninety-two percent of all DHs were present for at least four weeks. Low-tension glaucoma eyes seem to consist of two different groups; one which develops recurrent DH and one which is very unlikely to bleed through its entire course.

Eye Diseases↗
PubMed1986

Retinal damage threshold of ophthalmic Q-switched Nd-YAG laser in monkey eyes.

Q-Switched Nd-YAG laser was irradiated to the ocular fundus of 24 eyes of 12 monkeys (Macaca fascicularis) using MICRORUPTOR II (LASAG AG, Thun, Switzerland) through the Goldmann type three-mirror contact lens. Multimode irradiation conditions were used; the pulse duration of 12 nanoseconds, spot size of 80 micrometers, convergence angle of 16 degrees and with various energy levels from 0.05 to 2.8 mJ. After irradiation, the fundus changes were observed by ophthalmoscopy and color fundus photography at 24 hours, 48 hours, 1, 2 and 5 weeks, and by fluorescein angiography at 24 hours, 1 and 5 weeks. Immediately after the irradiation and at 2 and 5 weeks, eyeballs were enucleated and histological observations were carried out. The fundus changes were more evident at 24 hours than at the immediate period after irradiation. At 24 hours, findings by fundus photography and fluorescein angiography were compared: both findings were in agreement. Consequently the retinal damage threshold was determined from the 24-hour findings; the threshold in ED50 was 296.3 microJ with 95% confidence limits from 249.8 to 351.1 microJ. These values corresponded to the retinal energy density of 3.5 J cm-2. Histological observations revealed that the site of damage was mainly in the retinal pigment epithelium when the irradiation was below 1.4 mJ. When the energy was increased to 1.9 mJ, the tissue damage extended to the middle layer of the neuroretina and also disruption of the Bruch's membrane occurred, leading to subretinal hemorrhage. With the energy of 2.8 mJ, destruction extended over wide areas including whole layers of the choroid and retina, leading to vitreous hemorrhage. Over the period of 5 weeks, proliferation of the retinal pigment epithelial cells took place and replaced the damaged retinal tissues.

Animals↗
PubMed1985

Surgical treatment of open-angle glaucoma.

The influence of intraocular pressure (IOP) on the visual field of glaucoma patients is discussed; the criterion level for postoperative IOP control was set at 20 mmHg. When the IOP exceeded this level for two consecutive months, the IOP control was judged to be a failure, and the surgical results were analysed by a life-table method. Argon laser trabeculoplasty (ALT) with 50 shots over 180 degrees of the angle was used routinely, because of fewer complications than with 360 degrees ALT. A second session sometimes improved the final success rate, which was about 57% in primary open-angle glaucoma and 94% in capsular glaucoma after a follow-up period of two years and two months. All patients (120 eyes) required drugs, but their use could be reduced in about 35%. The IOP distribution in successful cases showed a peak at 16 to 17 mmHg, and the IOP was 15 mmHg or less in 21%. In trabeculectomy, pretreatment with topical indomethacin and steroid drip infusion was advocated, and concentrated sodium hyaluronate was used during surgery. These procedures reduced the incidence of shallow anterior chamber and associated choroidal detachment. The final success rate was about 60% after five years of follow-up. The IOP distribution after more than two years peaked at 13 to 15 mmHg, and the IOP was 15 mmHg or less in 53%.

Biomechanical Phenomena↗
PubMed1985

Laser therapy for glaucoma.

Three laser techniques for the treatment of glaucoma are described. The short-burn technique of argon laser iridotomy permitted perforation of the peripheral iris in one session without serious complications, thereby alleviating pupillary block in angle-closure glaucoma. The rates of successful intraocular pressure (IOP) control and visual acuity loss due to cataract progression were similar in laser iridotomy and surgical iridectomy. The tonographic outflow facility remained unchanged after argon laser iridotomy. Techniques of argon laser trabeculoplasty (ALT) to the anterior and posterior aspects of the trabecular band were evaluated. The anterior ALT gave fewer complications, but a lower IOP control rate than the posterior ALT. Posterior ALT over 180 degrees with about 50 burns gave fewer complications than treatment over 360 degrees with about 100 burns, yet the final effects in IOP control were better after the 180 degrees than after the 360 degrees treatment. Nd-YAG laser irradiation can separate dysgenetic iris insertion from the trabecular band in developmental glaucoma without serious complications. This Nd-YAG laser goniotomy may be useful for the treatment of juvenile primary developmental glaucoma.

Adolescent↗