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ABSTRACT: To evaluate the relationship of axial length (AXL), intraoperatively assessed posterior vitreous detachment (PVD) status, and surgical outcomes of diabetic vitrectomy.
Retrospective, consecutive case series. Clinical records were reviewed for 115 eyes (50 males, 65 females) with more than a 6-month follow-up who underwent diabetic vitrectomy from a single surgeon. Thirty-three eyes had vitreous haemorrhage, 37 had tractional retinal detachment (TRD) threatening the macula, 43 had TRD involving the macula, and two had neovascular glaucoma. AXL was measured preoperatively by ultrasonography, and PVD status was classified intraoperatively: broad vitreo-retinal adhesion as no PVD, PVD at the macular area with attachment at the disc as incomplete PVD, and complete PVD.
Forty-four eyes had no PVD, 23 had incomplete PVD, and 48 had complete PVD. A majority of the no PVD group had macula off TRD (97.7%), whereas vitreous haemorrhage (68.7%) predominated in the complete PVD group. Longer AXLs were noted in the complete PVD group compared with the no PVD and incomplete PVD groups (ANOVA in three groups P=0.0001). Univariate analysis showed that AXL had an influence on anatomical success (P=0.02). Multiple logistic regression analysis yielded that PVD status is a significant predictor of the final best corrected visual acuity (BCVA)>20/100, and BCVA>20/40 (P=0.01, P=0.02).
Intraoperatively assessed PVD status is a prognostic factor for functional outcomes of diabetic vitrectomy. Shorter AXL was associated with lesser PVD. In eyes with a lack of PVD, careful timing and decision of surgery are mandatory.
Eye (London, England) 07/2010; 24(7):1273-8. · 1.97 Impact Factor
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The British journal of ophthalmology 07/2009; 93(6):836-7. · 2.92 Impact Factor
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ABSTRACT: To investigate the progression of cataract after a high dose (25 mg) intravitreal triamcinolone acetonide injection in patients with macular oedema secondary to diabetes and retinal vein occlusion.
This prospective interventional case series study included 38 patients (76 eyes) with diabetic retinopathy or retinal vein occlusion diagnosed with clinical examination and fluorescein angiography. The patients were treated with 25 mg IVTA in their one eye with macular oedema and the fellow eyes served as a control. Patients were asked to return the next day and weekly for 1 month and monthly thereafter by 6 months post-operative. The progression of the cataract using photographic evaluation according to the Lens Opacities Classification System III was documented and statistical analysis was done using the Kaplan-Meier survival analysis and the log-rank test.
Among the 38 treated eyes, there was an increase of cataract degree by 1 grade at the end of 6 months in 10 patients. The types of progressed cataract were PSC in seven patients, cortical in six patients, and nuclear sclerosis in one patient. Six months after the injections, there was a significantly higher rate of progression of PSC (P=0.023, log-rank test) and cortical opacities (P=0.011) in the treated group while the progression of nuclear cataract was not significantly different between the treated eye and the control eye.
A high-dose (25 mg) intravitreal triamcinolone acetonide injection induces the progression of cortical and posterior subcapsular opacity in patients with diabetic macular oedema and retinal vein occlusion.
Eye 08/2008; 22(7):895-9. · 1.85 Impact Factor
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Eye 08/2004; 18(7):745-6. · 1.85 Impact Factor
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ABSTRACT: We describe a corneal limbal technique of intravitreal injection for use in cases in which it is difficult to confirm the position of the needle. Using this translimbal approach, the needle's position is easily identified and the intravitreal injection can be given using topical anesthesia. This technique is an option in eyes with a cloudy cornea or a large iridectomy.
Journal of Cataract [?] Refractive Surgery 07/2001; 27(6):811-3. · 2.26 Impact Factor
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ABSTRACT: The present study investigated the effects of transforming growth factor (TGF)-beta on retinal pigment epithelial (RPE) transformation in a simplified model and also whether or not TGF-beta exhibits similar proliferation effects on transformed RPE cells that it has on primary RPE cells. Furthermore, we examined the cell proliferation effects of RPE-conditioned medium (CM). A vertical wound measuring 2 mm in diameter was made on primary RPE monolayers. The expression of alpha-smooth muscle actin (SMA) by the cells located at the wound edges was observed using a confocal microscope under immunofluorescent staining. Cell proliferation was measured by incorporating 3H-thymidine into DNA. The presence of alpha-SMA was observed in the cells within the wound after treatment with TGF-beta2, while negative expression was observed in control cells. TGF-betas inhibited the proliferation of the primary cultures of RPE cells in a dose-dependent manner, but the spindle-shaped late-passaged RPE cells were not inhibited by these growth factors. The medium conditioned by RPE cells stimulated the proliferation of subconjunctival fibroblasts and inhibited the proliferation of primary RPE cells, in a manner similar to TGF-beta. These findings demonstrate that TGF-beta-stimulated RPE cells may evoke proliferative vitreoretinopathy through mesenchymal transformation and cell proliferation.
Yonsei Medical Journal 07/2001; 42(3):271-7. · 1.14 Impact Factor
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British Journal of Ophthalmology 12/2000; 84(11):1329-30. · 2.90 Impact Factor
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ABSTRACT: Several techniques are used to reposition dislocated intraocular lenses (IOLs). Most place a suture loop around the end of the haptic. However, in cases of a dislocated capsular bag containing the IOL, a dislocated IOL with a large haptic, or a miotic pupil, it is not easy to see the haptic ends to place the suture loop. We describe a scleral fixation technique that uses 2 corneal tunnels. A double-armed 10-0 polypropylene suture loop can be introduced through 1 corneal tunnel and placed around any accessible part of the haptic with the help of a bent 26 gauge needle. This modified technique is an easy and effective way to reposition the IOL.
Journal of Cataract [?] Refractive Surgery 11/2000; 26(10):1439-41. · 2.26 Impact Factor
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ABSTRACT: We used endoscopic laser photocoagulation to treat neovascular glaucoma in eight eyes of seven patients. New vessels of the iris and anterior chamber disappeared or stabilized after photocoagulation in seven eyes (88%), while the vision improved in four eyes (50%). The endoscopy was excellent for observing the peripheral retina and ciliary process tissue. We found the endoscopic laser was suitable for wider photocoagulation of ischemic retina against media opacity.
Yonsei Medical Journal 09/2000; 41(4):445-9. · 1.14 Impact Factor
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ABSTRACT: Suprachoroidal hemorrhage(SH) may cause the expulsion of the intraocular contents. Vitreous incarceration in the wound and retinal detachment with SH are extremely poor prognostic signs. Treatment modalities depend on the severity of eye damage. This particular patient had "kissing" hemorrhagic choroidal detachment which completely filled the vitreous cavity after cataract surgery. It seemed to be inoperable. Secondary surgery was delayed 3 days to lower IOP to normal levels. The eye underwent anterior drainage sclerotomy under constantly-maintained limbal or pars plana infusion fluid line pressure. The authors performed a pars plana vitrectomy, followed by perfluorocarbon liquid injection and a silicone oil tamponade. After this surgical approach, the patient attained an attached retina and a visual acuity of 5/200 at the 3 month follow-up.
Korean Journal of Ophthalmology 07/2000; 14(1):41-4.
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ABSTRACT: Isocyanates are part of a group of important chemicals necessary in the production of adhesives, synthetic rubbers, and a variety of plastics. They are known to have minimal toxic effects when administered locally. However, we experienced a case of damage involving the entire eyeball in a person who accidentally exposed his eye to isocyanates. The patient presented with inflamed conjunctiva, and shrunken cornea and sclera, with focal atrophic changes in the iris. The lens and vitreous were opacified. After removal of the lens and vitreous, there were large areas of atrophic retina and areas of retinal necrosis with holes. We found that locally absorbed isocyanates can cause damage to the entire eyeball. Therefore, we recommend that if there is any evidence of isocyanate penetration, early vitrectomy should be performed to help in determining the extent of retina damage and to decrease the amount of toxic substance in the vitreous.
Korean Journal of Ophthalmology 07/2000; 14(1):38-40.
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ABSTRACT: Retinal pigment epithelial (RPE) cells transdifferentiate in culture, a transition which is accompanied by a shift in biological activity. The present study investigates whether transforming growth factor (TGF)-beta has the same effects on morphologically transformed RPE cells that it has on primary RPE cells. It also evaluates the autocrine and paracrine activities of TGF-beta s synthesized by RPE cells as well as the anti-TGF-beta effect of mannose-6-phosphate (M-6-P). RPE cells were subcultured at the sixth passage to induce morphological change. The effect of second passaged RPE-conditioned medium (CM) on DNA synthesis was evaluated by the incorporation of 3H-thymidine in rabbit subconjunctival fibroblasts (SCFs) and primary RPE cells. The presence of TGF-beta in RPE-CM was determined using immunoblotting analysis. And the inhibitory effect of M-6-P on cell proliferation mediated by RPE-CM was also analyzed using 3H-thymidine incorporation into DNA. TGF-beta 1, TGF-beta 2, and TGF-beta 3 inhibited the proliferation of the primary cultures of RPE cells in a dose-dependent manner, but the spindle-shaped sixth passaged RPE cells were not inhibited by these growth factors. The medium conditioned by RPE cells stimulated the proliferation of SCFs and inhibited the proliferation of primary RPE cells, in a manner similar to TGF-beta. When this medium was precipitated with either anti-TGF-beta 1, anti-TGF-beta 2, or anti-TGF-beta 3 antibodies, all three TGF-beta s, with an apparent molecular size of 25 kDa, were detected. Mannose-6-phosphate significantly blocked the effect of RPE-CM on cell proliferation. These findings indicate that RPE cells produce biologically functional TGF-beta s and that M-6-P can block the inhibitory effect of RPE-CM on cell proliferation.
Korean Journal of Ophthalmology 07/1999; 13(1):16-24.
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ABSTRACT: The pathogenesis of diabetic retinopathy has not been fully explained. The earliest histological lesion is the loss of intramural pericytes and thickening of the basement membrane. Increased activity of the polyol pathway is a probable mechanism for these two abnormalities. Investigations have suffered from the lack of an exact animal model simulating the human condition. Examination of the retina in the spontaneously diabetic SHR/N:Mcc-cp rat demonstrated degeneration and loss of intramural pericytes, a progressive increase in basement membrane thickness, and microinfarctions with an area of non-perfusion. Therefore, this model may be used to clarify the biochemical mechanisms linking the metabolic abnormalities of diabetes and retinopathy.
Yonsei Medical Journal 11/1998; 39(5):453-62. · 1.14 Impact Factor
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ABSTRACT: We evaluated the efficacy of tissue plasminogen activator in treating experimental suprachoroidal hemorrhage. Suprachoroidal hemorrhage was created in 30 white rabbit eyes by implanting four pieces of small, exogenously formed blood coagula into the suprachoroidal space. Animals were randomized for treatment with a surgical sponge soaked in 25, 50, or 75 microg of tissue plasminogen activator (tPA) or balanced salt solution (BSS) as a control. The time when initiation and completion of clot dissolution occurred was established, and histological examination was performed to assess damage. Clot dissolution started within 30 min in the 50- and 75-microg tPA group, whereas it took 2.75 days in the control group; complete dissolution of blood clots took 4.5 h in the 75-microg tPA group and 14 days in the control group. Histological examination revealed a minimal change in photoreceptors within 6 h after treatment with 75 microg tPA. Treatment of suprachoroidal hemorrhage with tPA seems to be effective, but further investigations for determining the effective and nontoxic dose are required.
Ophthalmologica 02/1998; 212(2):120-5. · 1.42 Impact Factor
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ABSTRACT: We propose a modified hidden Markov model (MHMM) that incorporates
nonparametric state duration and state duration-dependent observation
probabilities to reflect state transitions and to have accurate temporal
structures in the HMM. In addition, to cope with the problem that
results from the use of insufficient amount of training data, we propose
to use the modified continuous density hidden Markov model (MCDHMM) with
a different number of mixtures for the probabilities of state
duration-independent and state duration-dependent observation. We show
that this proposed method yields improvement in recognition accuracy in
comparison with the conventional CDHMM
IEEE Transactions on Speech and Audio Processing 10/1996; · 2.29 Impact Factor
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ABSTRACT: We propose a new method of finding discriminative state-weights recursively using the generalized probabilistic descent method. This method is implemented with minor modification of the conventional parameter estimation and recognition algorithms by constraining the sum of the state-weights to the number of states in a recognition unit, and can be applied to continuous speech recognition as well as isolated word recognition. We confirm the validity of the method with phoneme-based and word-based state-weighting schemes for three kinds of recognition tasks.
IEEE Signal Processing Letters 10/1996; · 1.39 Impact Factor
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Speech Communication. 01/1996; 19:197-205.
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ABSTRACT: In a Korean connected digit recogniser, duration modelling is
necessary to reduce insertion and deletion errors due to monophonemic
digits, which cannot usually be corrected even by discriminative
training algorithms. Here the authors incorporate context-dependent word
duration modelling directly in a decoding algorithm to reduce those
errors. While incorporating duration information in the postprocessing
stage shows little improvement over a baseline system, the proposed
method reduces word error rates by ~10% for unknown length decoding when
both maximum likelihood estimation and generalised probabilistic descent
training are used
Electronics Letters 10/1995; · 0.96 Impact Factor
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ABSTRACT: A closed eyeball model was designed to estimate the chorioretinal adhesion of the laser-photocoagulated region. We used it to measure the duration of development of retinal detachment during vitrectomy before and after killing the test rabbits. During testing, negative pressure was applied into the vitreous cavity of the pigmented rabbits. Laser burns were produced in the posterior retina by exposure to an argon blue-green laser beam with a focus diameter of 200 microns of 0.1 to 0.2 second duration and 150 to 250 mW intensity. One hour and one, two, five, seven and fourteen days following laser photocoagulation, vitrectomy was done with a cutting rate of 500 per minute, aspiration pressure of 50 mmHg and infusion pressure of 55.2 mmHg. After core vitrectomy, the rabbit was killed with an intravenous bolus of 100 mg sodium pentobarbital solution. After killing the rabbit, the vitreous cavity was continuously aspirated under the pressure of 25 mmHg while the infusion was stopped. The changes of the fundus, especially development of retinal detachment, were observed in the laser-treated and untreated regions before and after killing the rabbit. When retinal detachment was noted anywhere before killing the rabbit, this postmortem change was not observed. One hour following laser photocoagulation, the laser-treated retina was detached during core vitrectomy before killing the rabbit, and the untreated area was not detached. One day following photocoagulation, the retina was intact before killing the rabbit. After killing the rabbit, the laser-treated retina was detached in four minutes and the untreated retina in 18 minutes postmortem.(ABSTRACT TRUNCATED AT 250 WORDS)
Yonsei Medical Journal 08/1995; 36(3):243-50. · 1.14 Impact Factor
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ABSTRACT: We compared the incidence of exposure of the hydroxyapatite implant after evisceration according to the position of scleral windows which allow rapid fibrovascularization into the implant. Three patients (10%) developed tissue breakdown and exposure of the hydroxyapatite, out of 30 patients who had external scleral windows located in a position just anterior to the insertion of each of the rectus muscles, whereas no patient developed exposure, out of 24 patients who had internal scleral windows located in a position just position just posterior to the insertion of each of the rectus muscles. Internal windows sealed with rectus muscles could prevent direct contact between implant and the overlying Tenon's capsule and conjunctiva. These findings seem to indicate that the rough spicular surface of the hydroxyapatite irritates and erodes the overlying Tenon's capsule and conjunctiva.
Ophthalmologica 02/1995; 209(6):319-22. · 1.42 Impact Factor
