Biomedical subjects

S M Hyung

Publications and source records attributed to S M Hyung.

16 recordsLinked to original sources

PubMed2001

Mid-term effects of trabeculectomy with mitomycin C in neovascular glaucoma patients.

Twenty four eyes from 23 neovascular glaucoma (NVG) patients, who underwent trabeculectomy with 0.2 or 0.4 mg/ml MMC in least the previous 6 months, were examined in order to evaluate the mid-term effects of a trabeculectomy with mitomycin C (MMC) in NVG. Success defined when an intraocular pressure (IOP) < 22 mmHg and > 5 mmHg with or without medication was observed. The mean IOP was reduced from 46.8+/-12.9 mmHg preoperatively to 18.2+/-12.0 mmHg at the last follow-up (mean = 25.8 months). The overall success rates at 1-, 3-, 6-, 9-, and 12-months after surgery were 71%, 58%, 50%, 29%, 29% respectively. The number of anti-glaucoma medications administered was significantly reduced from 2.6+/-0.7 preoperatively to 0.9+/-1.0 postoperatively (Wilcoxon signed rank test, p = 0.005). In addition both the intraoperative MMC concentration and application time had no influence on lowering the IOP (logistic regression analysis, p = 0.228, 0.910, respectively). There was a similar incidence of postoperative complications in both the success and failure group. These results suggest that a trabeculectomy with MMC is an effective surgical procedure in NVG patients and the MMC concentration is not crucial for reducing the IOP postoperatively.

Adult↗

PubMed1999

Midterm follow-up of necrotic bleb excision and advancement of the fornical conjunctiva.

Mitomycin C has improved the success rate of glaucoma filtering surgery in patients at high risk for surgical failure. However chronic hypotony is marked by decreased vision and a late-onset leaking bleb after filtration surgery using mitomycin C. Bleb excision and conjunctival advancement is the method of choice to repair bleb leakage and chronic hypotony. Five eyes from five patients were received glaucoma filtration surgery with topical mitomycin C. All of the patients' blebs were avascular and transparent. The reasons for bleb excision were two spontaneous bleb leaks, two traumatic bleb leaks and one case of severe irritation. The mean follow-up period was 18.4 +/- 8.3 months (ten to 29 months). Cataract surgery was combined in one eye. Postoperative intraocular pressure (IOP) increased from 2.3 +/- 1.5 mmHg to 9.5 +/- 3.7 mmHg at nine months postoperatively in four eyes. It went from 28 mmHg to 40 mmHg in one patient with uveitis, for whom a second trabeculectomy with mitomycin C; 0.4 mg/ml for 3 minutes, was performed. After surgery, IOP decreased to 4 mmHg in three months. Postoperative visual acuity improved four snellen lines in three eyes. A partially avascular bleb recurred in three eyes, a corneal bleb in one eye and blepharoptosis, which disappeared spontaneously at four months postoperatively, in one eye. Necrotic bleb excision and advancement of fornical conjunctiva were useful methods to increase IOP and to improve visual acuity for the patient experiencing irritation symptoms, and for leaking blebs, and hypotonic maculopathy.

Adult↗

PubMed1998

Subconjunctival silicone oil drainage through the Molteno implant.

To describe silicone oil drainage from the vitreous cavity to the subconjunctival space through a Molteno implant. A 52-year-old aphakic man with a Molteno implant inserted after lensectomy, vitrectomy and intravitreal silicone oil injection visited our hospital. The Molteno tube was located in the anterior chamber with two silicone oil drops on it. Corneal dellen, induced by marked bleb-like elevation of the conjunctiva was noted during follow-up and excision biopsy was attempted. The conjunctival elevation consisted of innumerable microdrops of silicone oil enclosed by inflammatory subconjunctival tissue. Silicone oil as well as aqueous humor had drained through the Molteno implant and glaucoma implant surgery may thus not be appropriate for the control of intraocular pressure of aphakia by intravitreal silicone oil before removal of oil.

Aphakia, Postcataract↗

PubMed1997

Management of chronic hypotony following trabeculectomy with mitomycin C.

Chronic hypotony is marked by decreased vision and late-onset leaking bleb after filtration surgery using topical mitomycin C; to manage this condition we followed a three-step approach: first, intrableb autologous blood injection; second, surgical exploration and additional suturing of the scleral flap; third, excision of the cystic bleb and advancement of a fornical conjunctival flap. For the avascular flap cystic blebs of five patients. In three of the six eyes, there was no increase of intraocular pressure (IOP); two eyes showed massive hyphema and were mildly resistant to the injection of autologous blood, and in one, a leaking hole was seen in the bleb wall two days after the injection of blood. Two eyes of three in which blood injection had failed, and another, in which the bleb had spread over more than half the eyeball, and which was the patient's only sighted eye, underwent the second step of the procedure. The remaining leaking eye, in which blood injection had been complicated, and another, in which spontaneous leakage from a thin avascular bleb had occurred, were subjected to the third step. After each of the three approaches, IOP increased on average from 1.67 to 5.67 mmHg, from 2.33 to 11.33 mmHg, and from 1.5 to 7 mmHg, respectively; each approach successfully improved vision. Intrableb autologous blood injection is a simple procedure for the management of chronic overfiltration and a way of determining whether excessive filtration is occurring through the scleral flap, in which case additional suturing is required, or in another way. Depending on the status of the bleb, additional suturing or excision of the cystic bleb and advancement of the fornical conjunctival flap are useful modalities for the treatment of late-onset leaking filtration bleb.

Adolescent↗

PubMed1996

Effects of postoperative mitomycin C eyedrop on trabeculectomy in refractory glaucoma patients.

To investigate the effects of postoperative mitomycin C (MMC) eyedrop as an adjunct to intraoperative MMC in refractory glaucomas, 15 eyes of 14 glaucoma patients (age; 47.0 +/- 15.5 years) in need of trabeculectomy were studied. Preoperative diagnoses were secondary glaucoma to uveitis in seven patients, neovascular glaucoma in four, pseudophakic glaucoma in three, and aphakic glaucoma in one. Six patients who had neovascular glaucoma or history of a failed trabeculectomy with intraoperative 0.2 mg/ml MMC received intraoperative 0.4 mg/ml MMC. The others received 0.2 mg/ml MMC for 3 minutes. During the follow-up period, postoperative MMC eyedrop was applied, depending on the condition of the filtration bleb. The eyedrop was 0.2 or 0.4 mg/ml, applied four times a day for one week. The follow-up period was 18.1 /+- 7.4 months. The success rates were 93.3%, 86.7%, and 78.0% at postoperative 1, 4, and 18 months, respectively. There was neither early hypotony nor wound leak. Corneal epithelial defects (26.7%), corneal ulcers (6.7%), and cataracts (6.7%) were, however, observed. Postoperative MMC eyedrop application was a convenient and effective adjunct to intraoperative MMC in refractory glaucomas.

Adult↗

PubMed1996

Evaluation of pupillary block component in angle-closure glaucoma.

To evaluate the amount of the pupillary block component in primary angle-closure glaucoma, the dark-room prone-position test was carried out in 30 eyes of 20 primary angle-closure glaucoma patients, before and one month after argon laser iridotomy. The pupillary block component in the prone position (5.8 +/- 5.6 mmHg), which is the amount of reduction in IOP rise in the post-laser dark-room prone-position test, composed 67.8% of the IOP rise in the pre-laser dark-room prone-position test (8.6 +/- 5.6 mmHg). The amount of the pupillary block component correlated significantly with the IOP rise in the pre-laser dark-room prone-position test (r = 0.880, P < 0.001). The amount of the non-pupillary block component was relatively constant and correlated poorly with the IOP rise in the pre-laser dark-room prone-position test (r = 0.163, P = 0.386). The pupillary block component was significantly larger than the non-pupillary block component in the eyes with an IOP rise of > or = 7 mmHg in the pre-laser dark-room prone-position test (P < 0.01). The dark-room prone-position test could be useful in evaluating the pupillary block component in angle-closure glaucoma eyes and helpful in making a decision for laser iridotomy.

Adult↗

PubMed1995

Induction of vitreolysis and vitreous detachment with hyaluronidase and perfluoropropane gas.

To simulate the posterior vitreous detachment (PVD) in the rabbit, 1 IU hyaluronidase and/or 0.2 ml of perfluoropropane gas was intravitreally injected. Ophthalmoscopic, light microscopic examination prepared by cryotechnique, electron microscopic examination, and electroretinogram were done on the 3rd and 28th postoperative days. As a result, the eyes undergone simultaneous intravitreal injection of 1 IU hyaluronidase and 0.2 ml perfluoropropane gas showed membranous structure split from the internal limiting membrane of the superior retina in 3 days after injection. The eyes also demonstrated membranous structure separated from the superior retina after 28 days, simulating vitreous detachment. On the contrary, neither agent alone induced vitreous detachment. No toxic retinal changes associated with simultaneous intravitreal injection of 1 IU hyaluronidase and 0.2 ml perfluoropropane gas were observed. Therefore, with a future support by histologic examination other than cryotechnique and by immunohistochemical analysis, the simultaneous intravitreal injection of perfluoropropane gas and hyaluronidase would be a promising method to induce vitreous detachment in non-vitrectomized eye.

Animals↗

PubMed1993

Effects of topical mitomycin C on glaucoma filtration surgery.

We studied the efficacy and safety of using topical mitomycin C (MMC) as an adjunct to glaucoma filtration surgery. Trabeculectomy was performed in 23 eyes of 19 patients with poor surgical prognosis. After the preparation of a scleral flap, 0.2 mg or 0.4 mg/ml MMC was applied to the exposed tissue for 5 minutes. The wound was then irrigated with 250ml of normal saline. The mean follow-up period was 7.8 months. Preoperative mean intraocular pressure (IOP) was 33.8mmHg, and the mean IOPs on 1, 3, 6, and 12 months after operation were 10.3, 12.5, 12.4 and 12.3mmHg, respectively. At postoperative 12 months, 74.7% achieved an IOP of less than or equal to 20mmHg without any antiglaucoma medication. There were early postoperative complications of aqueous leaking from conjunctival wounds in 3 eyes (13.0%), shallow anterior chamber in 2 eyes, and hyphema in one eye and one eye had long-term hypotony lasting more than 3 months. Although MMC is simple to use, it is a potent adjunct to glaucoma filtration surgery, more work should follow to determine the mechanism of action, indications, dosage and optimal exposure time of MMC.

Administration, Topical↗

PubMed1993

Effects of sodium hyaluronate on filtration bleb in rabbits.

Sodium hyaluronate can be used during a trabeculectomy to prevent early postoperative hypotony and shallow anterior chamber. To determine its long-term effect on the outcome of filtration surgery, fifteen rabbits underwent a posterior-lip sclerectomy in both eyes. Into their right eyes 0.2ml sodium hyaluronate, and into left eyes 0.2ml balanced salt solution were injected intracamerally. Gross and histopathological differences of bleb were observed. There was no statistically significant difference in longevity of the filtration bleb.

Animals↗

PubMed1992

Ocular dimensions with aging in normal eyes.

To quantify the dynamic changes taking place in the anterior segment, we measured the anterior chamber depth (ACD), lens thickness (LT) and their difference between sexes and age groups in normal eyes using contact ultrasonography and anterior chamber photography. There were 141 women (241 eyes) and 76 men (130 eyes) between the ages of 10 and 70 years. In normal eyes, the lens thickness was increased and the anterior chamber depth was decreased with aging in both sexes. The anterior chamber depth showed an accelerated decrease between the 4th and 5th decades in females and the ratio of anterior chamber depth to axial length was smaller in females than in males after the 5th decade. The results suggested that the prevalence of angle closure glaucoma will be increased in females after middle age.

Adolescent↗

PubMed1992

Optic disc of the myopic eye: relationship between refractive errors and morphometric characteristics.

Because the optic disc in myopic eyes is different from a normal optic disc, there are many difficulties in examining the optic discs of myopic eyes. To study optic disc change due to myopia, we performed a morphometrical study of stereophotographs of 61 men, 109 eyes, who had no glaucoma history. The range of refractive error was from +0.75 diopter to -12.75 diopter, and all subjects had intraocular pressure below or equal to 21 mmHg. According to the increase in the myopic degree, the temporal slope of the disc cup was significantly decreased, but the ratio of the vertical disc diameter (VDD) to the horizontal disc diameter and the ratio of the width of peripapillary atrophy (PPA) to the VDD were significantly increased. The above results suggests that in high myopia the optic disc was tilted and the rim-cup border was indistinct and there are some problems in the estimation of the morphometric parameters. Also in evaluation of the PPA of myopic glaucoma patients, there may be some difficulty in deciding whether it is due to myopic change or glaucomatous damage.

Adolescent↗

PubMed1992

Effects of aqueous humor on filtering bleb in rabbits.

Preoperative aqueous humor, known to inhibit the growth of fibroblasts in tissue culture assay, was used as an adjunct to filtering surgery in rabbits to determine its effect in vivo on the outcome of filtering surgery. Fifteen rabbits underwent a posterior-lip sclerectomy in both eyes. In experimental eyes 1.4 ml preoperative aqueous humor and in fellow eyes 1.4 ml balanced salt solution were injected intracamerally. Gross and histopathological differences of bleb were observed. In this animal experiment, although there was no statistical significance or late postoperative effect, the rabbit eyes refilled with preoperative aqueous humor intracamerally just after filtering surgery, had a larger bleb and less fibroconnective tissue on the bleb than the control eyes in the early postoperative period.

Animals↗

PubMed1991

Fibrous capsule surrounding silicone encircling band and Gore-Tex surgical membrane.

Since the anterior chamber tube shunt to an encircling band(ACTSEB) is not a simple procedure, an extended polytetrafluoroethylene (e-PTFE)-silicone tube (anterior chamber tube shunt to a surgical membrane; ACTSSM) was attempted as a new glaucoma drainage implant. To see whether the newly-modified, two-fold e-PTFE-silicone tube implant could prevent early hypotony and to compare the tissue response to each implant, ACTSEB and ACTSSM procedures were done in normal colored rabbit eyes. It was found the ACTSSM kept the depth of the postoperative anterior chamber normal. And in general, foreign body responses were light microscopically similar. The fibrous capsule lining the e-PTFE was composed of thicker, less dense fibroblasts, as well as less collagen than that lining the silicone encircling band. These findings seemed to be related to the difference in the pressure-lowering capacity between ACTSEB and ACTSSM.

Animals↗

PubMed1990

Optic disc and early glaucomatous visual field loss.

In the early stages of glaucoma, the disc changes prior to visual field loss, so assessment of the optic disc is very important for the evaluation of the glaucoma patient. The aim of this study is to assess the glaucomatous disc and to look for the features of the optic disc that are commonly associated with early visual field loss. Forty-three eyes of 28 patients were included in this investigation. The criteria for inclusion were a cup/disc(C/D) ratio of more than 0.4 by direct ophthalmoscopy, no visual field defect with Goldmann perimetry, and open anterior chamber angle. Each optic disc was photographed with a Canon fundus camera with Polaroid 600 Plus film. Each photographic set was then examined stereoscopically for morphologic parameters: 1) comparison of vertical versus horizontal C/D ratio; 2) presence of nasal cupping; 3) presence of overpassing vessels; 4) presence of baring of circumlinear vessels; 5) presence of peripapillary atrophy; 6) ratio of the thinnest neuroretinal rim(NRR) width in the vertical sectors of the NRR width of the temporal sector. All subject's central visual fields were examined with an automated static perimeter, Humphrey program C30-2 with STATPAC. The C/D ratio estimated by direct ophthalmoscopy consistently showed a smaller C/D ratio than that found by the stereophotographic method. The parameter with the highest probability value to differentiate between the optic disc of the early visual field loss and the optic disc of normal subjects was "Ratio of the thinnest NRR width in the vertical sectors to the NRR width of the temporal sector less than or equal to 85%". Although it has less resolving power than slide film, a stereo disc photograph with Polaroid film is a quick and simple method of recording changes, and the ratio of the thinnest NRR width in the vertical sectors to the temporal sector is a good predictive parameter for detection of early visual field loss.

Adolescent↗

PubMed1989

Visual prognosis in advanced glaucoma.

Many surgeons have noted that when the visual field is markedly constricted, immediate and permanent loss of central vision may follow otherwise successful glaucoma surgery. The present study was undertaken to assess the relative risk of surgical therapy in the loss of central vision in patients with advanced glaucoma. We reviewed the records of 44 eyes (including 8 macular split eyes) of 36 patients who had undergone trabeculectomy for intraocular pressure (IOP) control. The patients were followed for a minimum of 4 months with an average follow-up of 4.1 years. None of the patient suddenly lost visual field following surgery when central vision was spared at the time of operation. There was good preservation of preoperative visual acuity except in 3 eyes which developed lens opacity. There was no progression of visual field loss when the IOP was controlled below 21 mmHg. There was good control of IOP of 43 eyes in 44 eyes operated. However, in one of the 2 reoperated eyes, we could not control the IOP below 21 mmHg.

Adolescent↗

PubMedDate not supplied

Effects of postoperative mitomycin C on glaucoma filtration surgery in rabbits treated preoperatively with antiglaucoma medications.

In a rabbit model, we evaluated the effects of topically applied postoperative mitomycin C (MMC) on the success rate of glaucoma filtration surgery in animals treated preoperatively with pilocarpine hydrochloride 4% and levobunolol hydrochloride (Betagan) for 16 weeks. Full-thickness filtration surgery was performed with a single 5-minute intraoperative exposure to a sponge soaked with 0.4 mg/mL MMC of one eye in nine rabbits in one group (group A) and to both eyes in 13 rabbits in a second group (group B). In addition, one eye of each rabbit in group B received a daily drop of 0.4 mg/mL MMC for 13 days after the operation. All of the eyes were then followed for 80 days. The intraoperatively applied MMC enhanced the success rate of the filtration surgery in the group A eyes. However, the eyes that also received postoperative drops of MMC (group B) had longer periods of reduced intraocular pressure (IOP) (P [chi-squared = 5.94] < .025), fewer bleb failures (P [chi-squared = 8.09] < .005), and more complications than the eyes that received only intraoperative MMC.

Administration, Topical↗