Biomedical subjects

Ko-Hua Chen

Publications and source records attributed to Ko-Hua Chen.

18 recordsLinked to original sources

PubMed2006

A novel strategy for corneal endothelial reconstruction with a bioengineered cell sheet.

Cellular organization of foreign grafts constructed from cultivated cells is critical to successful graft-host integration and tissue repair. This study described a novel human corneal endothelial cell (HCEC) therapeutic method, where cultivated adult HCEC sheet with uniform orientation was prepared and transplanted to a rabbit cornea. Having a correct morphology and intact barriers, the HCEC sheet was made by the temperature-modulated detachment of monolayered HCECs from thermoresponsive poly(N-isopropylacrylamide) (PNIPAAm)-grafted surfaces and was delivered with proper polarity to the corneal posterior surface by a bioadhesive gelatin disc. Results of the in vivo studies, including the follow-up clinical observations and histological examinations, showed the laminated HCEC sheet was successfully integrated into rabbit cornea denuded with endothelial layer after the biodegradation of gelatin carrier. These data indicate the feasibility of the proposed procedure in cell therapy for corneal endothelial cell loss.

Acrylamides↗

PubMed2006

Bioengineered human corneal endothelium for transplantation.

OBJECTIVE: To investigate whether the bioengineered human corneal endothelial cell (HCEC) monolayers harvested from thermoresponsive culture supports could be used as biological tissue equivalents. METHODS: Untransformed adult HCECs derived from eye bank corneas were cultivated on a thermoresponsive poly-N-isopropylacrylamide-grafted surface for 3 weeks at 37 degrees C. Confluent cell cultures with a phenotype and cell density similar to HCECs in vivo were detached as a laminated sheet by lowering the culture temperature to 20 degrees C. In vitro characteristics of the HCEC sheets were determined evaluating their viability and by scanning electron microscopy, immunohistochemistry, and histological studies. RESULTS: After separation from culture surfaces via a thermal stimulus, the HCEC sheets remained viable. Polygonal cell morphology and multiple cellular interconnections were observed throughout the HCEC sheets. Immunolocalization of zonula occludens-1 and Na+,K+-adenosine triphosphatase (ATPase) indicated the formation of tight junctions and the distribution of ionic pumps at the cell boundary. In addition, we ascertained that cultured HCECs have a monolayered architecture that mimics native corneal endothelium. CONCLUSION: These data suggest that a well-organized and functional HCEC monolayer can feasibly be used as tissue equivalents for replacing compromised endothelium.Clinical Relevance Bioengineered human corneal endothelium fabricated from thermoresponsive supports can potentially offer a new therapeutic strategy for corneal endothelial cell loss.

Aged↗

PubMed2006

Propionibacterium acnes DNA from an explanted intraocular lens detected by polymerase chain reaction in a case of chronic pseudophakic endophthalmitis.

We report a case of Propionibacterium acnes DNA from the explanted intraocular lens (IOL) a 76-year-old man with delayed-onset chronic endophthalmitis. The detection was by polymerase chain reaction (PCR). Slitlamp microscopic examination showed cells and flare in the anterior chamber, keratic precipitates on the endothelium, and multiple white plaques on both surfaces of the IOL. Propionibacterium acnes DNA was found in both the aqueous humor and the explanted IOL by PCR. Scanning electron microscopy showed diphtheroid particles, a coating of biofilm-like deposits, as well as scattered crystals on the surface of the explanted IOL and supported the possibility of P acne colonies on the IOL.

Aged↗

PubMed2006

Effect of charge and molecular weight on the functionality of gelatin carriers for corneal endothelial cell therapy.

Cell transplantation strategies usually involve the use of supporting carrier materials because of the soft and fragile nature of these grafts. In this work, a cell-adhesive gelatin hydrogel carrier was fabricated to deliver cultivated human corneal endothelial cell (HCEC) sheets, which were harvested from thermo-responsive poly(N-isopropylacrylamide) (PNIPAAm)-grafted culture surfaces. The carrier disks, consisting of gelatins with a different isoelectric point (IEP = 5.0 and 9.0) and a molecular weight (MW) ranging from 3 to 100 kDa, were subjected to 16.6 kGy gamma irradiation for sterilization. The effect of IEP and MW of the raw gelatins (i.e., before irradiation) on the functionality of sterilized disks was studied by determinations of mechanical property, water content, dissolution degree, and cytocompatibility. Irrespective of the IEP of raw gelatin, hydrogel disks prepared with high MW (100 kDa) exhibited a greater tensile strength, lower water content, and slower dissolution rate than those made of low MW gelatin (8 and 3 kDa). From the investigation of cellular responses to the disks, the negatively charged gelatin (IEP = 5.0) groups were more cytocompatible when compared with their positively charged counterparts (IEP = 9.0) at the same MW (100 kDa). Additionally, in the negatively charged gelatin groups, only a slight increase in pro-inflammatory cytokine expression was observed with increasing MW of gelatin from 3 to 100 kDa. It is concluded that the gamma-sterilized hydrogel disks made from raw gelatins (IEP = 5.0, MW = 100 kDa) with appropriate dissolution degree and acceptable cytocompatibility are capable of providing stable mechanical support, making these carriers promising candidates for intraocular delivery of cultivated HCEC sheets.

Animals↗

PubMed2006

Siderosis oculi: visual dysfunctions even after iron removal: a role of OCT.

Four males with sidersosis oculi were reviewed. Vitreous/anterior chamber angle irons (cases 1 and 3) were misdiagnosed initially and discovered later. In case 2, the retina-incarcerated iron was long ignored. Exceptionally in case 4, the iron was encapsulated by using optical coherence tomography (OCT). Preoperatively, in cases 1 and 4, the injured eye's vision, electro-oculogram, and electroretinogram were reduced compared with the other eye. In three cases, field defects were relevant to their iron locations. Postremoval, iron-impaired retinal functions didn't obviously improve. Early iron removal seems vital. OCT identified iron encapsulation, ameliorating iron toxicity. Consistently, field defect in case 4 was nonprogressive.

Adolescent↗

PubMed2006

Corneal injury by anti-misting agent in swim goggles: a case report.

PURPOSE: To report a case of corneal injury by swim goggle anti-misting agent. METHODS: Case report. RESULTS: A 47-year-old man presented with ocular injury caused by swim goggle anti-misting agent. Two weeks previously, the patient felt sudden ocular pain and grit after pool water flooded his goggles while swimming. Before the patient's swim, a copious amount of anti-misting agent was sprayed inside his goggles. On examination, severe corneal epithelial defect and stroma edema of the right eye were noted. Best-corrected visual acuity (BCVA) was 20/40. Right eye corneal thickness was 625 microm. Topical corticosteroids, antibiotic eye drops, and oral tetracycline were started. After 1 week of treatment, the epithelial defect of his right cornea improved slightly. Stromal edema decreased mildly. Epithelial defect persisted at 1 month follow-up. Right eye BCVA remained 20/40. Three months after treatment, the right eye epithelial defect healed completely. Mild diffuse superficial stromal opacity was noted. BCVA improved to 20/20. At 1-year follow-up, right eye corneal thickness was 547 microm, which was thinner than the left eye. Right eye corneal endothelial cell density measured approximately 1500 cells/mm2, which was less than the left eye at 2300 cells/mm2. The faint, diffuse stromal opacity disappeared; however, white subepithelial plaques were noted in the cornea centers. After 1 month of treatment with topical corticosteroids, the plaques subsided completely. The corneas remained clear at 2-year follow-up. CONCLUSION: Anti-misting agent can cause severe corneal injuries, including persistent epithelial defects, stromal edema and opacity, endothelial cell loss, and subepithelial plaque.

Anti-Bacterial Agents↗

PubMed2006

Herpes simplex keratitis following excimer laser application.

PURPOSE: To report two cases of herpes simplex keratitis following excimer laser application. METHODS: Two immunocompetent patients with no history of ocular viral infection developed ulcers after LASIK and phototherapeutic keratectomy (PTK), respectively. RESULTS: Antiviral treatment was administered, and the lesions healed within 14 days. CONCLUSIONS: These two cases suggest that herpes simplex virus was associated with the use of the excimer laser.

Adult↗

PubMed2005

Corneal calcification: chemical composition of calcified deposit.

BACKGROUND: The aim of this study was to quickly and quantitatively detect the chemical composition of the calcified deposit on the surface of a surgically excised cornea by using vibrational microspectroscopy. METHODS: Both attenuated total reflection (ATR)/Fourier transform infrared (FTIR) and confocal Raman microspectroscopies were used to evaluate the chemical composition of the excised corneal calcified opaque deposit of a 50-year-old male patient. Hydroxyapatite (HA) was used as a reference. RESULTS: Microscopic observations indicated that a whitish-grayish opaque plaquelike deposit was observed. A peak at 1020 cm(-1) assigned to the stretching vibration of phosphate of the poorly crystalline, immature and nonstoichiometric HA was observed from the IR spectrum of the corneal calcified deposit, as compared with the peak at 1030 cm(-1) of the mature, crystalline and stoichiometric HA reference sample. Higher contents of two IR spectral peaks at 871 cm(-1) due to the type-B carbonated apatite and at 866 cm(-1) corresponded to a labile carbonate were also evidenced in the corneal calcified deposit. The predominate peak at 959 cm(-1) due to the stretching mode of phosphate was also found in the Raman spectrum of corneal calcified deposit. CONCLUSIONS: The corneal calcified deposit was evidenced to contain much poor crystalline and immature HA having higher content of the type-B carbonated apatite within the corneal collagen matrix. The process of corneal calcification still proceeds on the surface of this cornea.

Apatites↗

PubMed2005

Retained antibiotic ophthalmic ointment on an intraocular lens 34 months after sutureless cataract surgery.

PURPOSE: To quickly examine the long-term retained oily-like material on the intraocular lens (IOL) of a sutureless cataract surgical patient. DESIGN: Observational case report. METHODS: Fourier transform infrared (FT-IR) and confocal Raman microspectroscopies were used to identify the deposited materials on explanted IOL. RESULTS: A 70-year-old man underwent a sutureless cataract surgery for his right eye. Garamycin ophthalmic ointment was postoperatively applied on the conjunctival fornix. His vision was improved to 20/25 after surgery but declined gradually to 20/400 half a year later. An oily-like hump on the anterior surface of IOL was found and he underwent IOL exchange after approximately 3 years. The oily-like material was identified by using FT-IR and Raman microspectroscopies to be garamycin ophthalmic ointment. CONCLUSIONS: Both FT-IR and Raman microspectroscopies can easily examine the retained antibiotic ophthalmic ointment on the IOL. Direct access of ophthalmic ointment into ocular anterior chamber through the sutureless incision is a potential risk.

Aged↗

PubMed2005

Multiple elements in the deposits of opacified Hydroview intraocular lens.

PURPOSE: To report the ultrastructural and elemental features of two opacified intraocular lenses (IOLs). DESIGN: Histopathologic case series. METHODS: Two opaque hydrophilic acrylic IOLs (Hydroview H60M, Bausch & Lomb Surgical Clearwater, Florida, USA) explanted from two Chinese patients in Taiwan. The explanted IOLs were evaluated by light microscopy, scanning electron microscopy, and energy-dispersive x-ray spectroscopy. RESULTS: Brownish granular and scattered crystal-like deposits were found in case 2, whereas only fine white granular deposits were found in case 1. Using EDX spectroscopy, the elements of deposits on IOL optics were calcium and phosphorus in case 1, but in case 2, fluorine, magnesium, and sodium were demonstrated in addition to calcium and phosphorus. CONCLUSIONS: Our study indicated a difference in morphology and elements of deposits on opaque IOL optics between these two cases. It was suggested that multiple elements may contribute to the formation of deposits.

Acrylic Resins↗

PubMed2005

Laser-assisted subepithelial keratectomy for dry eye associated with soft contact lenses.

PURPOSE: To evaluate the efficacy and safety of laser-assisted subepithelial keratectomy (LASEK) in myopic patients with preoperative dry eye associated with extended soft contact lens use. SETTING: Department of Ophthalmology, Taipei Veterans General Hospital, Taipei, Taiwan. METHODS: This nonrandomized prospective interventional case series study comprised 9 patients (18 eyes) with dry eye and keratoconjunctivitis associated with long-term complicated soft contact lens use. Prior to LASEK surgery and for 1 year following surgery, measurements and comparisons were made of uncorrected visual acuity, best corrected visual acuity (BCVA), manifest refraction, symptoms, tear function, ocular surface abnormality, and corneal sensitivity. RESULTS: No significant differences (P > .05) in the mean results of the Schirmer test with anesthesia and tear breakup times before and after LASEK were evident. Corneal sensitivity recovered within 1 month after LASEK. No complications occurred during or after LASEK. Subepithelial haze and superficial punctate epithelial defects occurred in 1 eye, representing a loss of 1 Snellen line of BCVA. CONCLUSION: Laser-assisted subepithelial keratomileusis in dry eyes and keratoconjunctivitis associated with complicated soft contact lens wearing was safe and efficacious.

Adult↗

PubMed2005

Ocular hypersensitivitiy to topical vancomycin in a case of chronic endophthalmitis.

PURPOSE: To report a case of ocular allergy to topical vancomycin eye drops. METHODS: Interventional case report. RESULTS: A 76-year-old man presented with progressive itching, soreness, and burning sensations, photophobia, and tearing in his left eye 3 days after completing 2 weeks of treatment with 5% vancomycin eye drops. He had been suffering for the previous 2 years from chronic recurrent endophthalmitis and secondary glaucoma associated with cataract surgery in his left eye. He denied any history of drug or food allergy. Examination by slit-lamp microscope showed left periorbital skin erosive rash, marked hyperemia of conjunctiva, central epithelial defect, corneal stromal edema, and Descemet membrane striae. Vancomycin skin tests were positive. The patient's symptoms resolved after discontinuing vancomycin eye drops and responded well to systemic corticosteroids, antihistamines, and topical corticosteroid treatments. Teicoplanin treated his endophthalmitis successfully. CONCLUSION: A case of hypersensitivity to topical vancamycin was reported. Patients who receive topical vancomycin should be informed of this possible adverse effect and instructed to contact their ophthalmologists if allergic reactions occur.

Administration, Topical↗

PubMed2004

Evidence of octacalcium phosphate and Type-B carbonated apatites deposited on the surface of explanted acrylic hydrogel intraocular lens.

Fourier-transform infrared (FTIR) microspectroscopy combining with attenuated total reflection (ATR) microsampling technique and micro-Raman spectrophotometer were used to detect the deposited materials on the surface of acrylic hydrogel intraocular lens (IOL) with or without ocular implantation. Surface morphology and the interface of this IOL were further examined by a confocal laser scanning microscope. The brand-new IOL exhibited a very smooth, transparent and featureless surface, but the explanted IOL had an irregular cerebriform-like opaque appearance. Both FTIR/ATR and Raman microspectroscopic analyses showed the deposits on the surface of acrylic hydrogel IOL after ocular implantation to consist of octacalcium phosphate (OCP) and Type B carbonated apatites, leading to the opalescence of acrylic hydrogel IOL. Both vibrational microspectroscopic examinations also confirmed the mineralization still in progress on the surface of acrylic hydrogel IOL after ocular implantation for 2 years.

Aged↗

PubMed2004

Linear-long incisions with a small optical zone for the correction of astigmatism in older patients.

PURPOSE: To evaluate the efficacy of astigmatic keratotomy (AK) by paired linear (transverse)-long incisions within a small optical zone in older patients with 3.00 diopters (D) or more of astigmatism who are intolerant of contact lenses, spectacles, or both. DESIGN: Prospective, noncomparative case series. PARTICIPANTS: Twenty-one eyes (20 patients; age range, 58-87 years) treated at clinics of the Taipei Veterans General Hospital were included in this study. METHODS: Paired linear incisions (90 degrees in length) with a central optical zone (OZ) of 4.5 mm were made to correct high astigmatism in older patients. The incisions were 80% of the corneal thickness and parallel to the axis of the steepest cylinder. MAIN OUTCOME MEASURES: Refraction, keratometry, corneal topography, and visual acuity with and without correction were measured as the outcome indicators. RESULTS: The mean course of the stabilization of corneal curvature was 1.8 months. Significant improvement from a preoperative corneal astigmatism of 4.52+/-1.39 D to a postoperative value of 1.82+/-0.88 D (P<0.0001) was shown. Marked axis deviations of more than 30 degrees were observed in 5 cases and corneal perforation was observed in 1 case. When the corneal curvature stabilized, uncorrected visual acuity was improved by 2 lines or more in 15 eyes (71.4%). Spherical equivalents and best-corrected visual acuity did not change significantly. Postoperative glare was absent in all patients. CONCLUSIONS: We conclude that AK by linear-long incisions extending from a small OZ is effective and safe for correcting astigmatism.

Aged↗

PubMed2004

Relapsing Mooren's ulcer after amniotic membrane transplantation combined with conjunctival autografting.

PURPOSE: To report a patient with Mooren's ulcer that relapsed 2 months after amniotic membrane (AM) transplantation and conjunctival autografting and its subsequent retreatment. DESIGN: Interventional case report. METHODS: We performed multilayered AM transplantation and conjunctival autografting from the opposite healthy eye to treat a corneoscleral perforation caused by Mooren's ulcer in a 60-year-old woman. MAIN OUTCOME MEASURES: Reformation of the anterior chamber, absence of inflammation, and restoration of visual acuity. RESULTS: The perforated corneoscleral lesion was sealed successfully by the AM and conjunctiva graft and led to a stable condition for 2 months. Relapsing corneal edema, keratic precipitates, and cell infiltration occurred along the margin of the conjunctival graft with severe vessel engorgement. After removing the conjunctival graft and regrafting of additional AM, the lesion subsided for at least 1 year. CONCLUSIONS: Amniotic membrane transplants may be useful in treating corneal perforation of immunologic origin, but conjunctiva and its vessels may play a role in the process of peripheral corneal destruction of Mooren's ulcer.

Amnion↗

PubMed2004

Toxic keratopathy associated with abuse of low-dose anesthetic: a case report.

OBJECTIVE: To describe the clinical course and treatment of toxic keratopathy associated with abuse of topical anesthetic at a very low concentration, 0.05%. METHOD: Case report. RESULT: A 47-year-old female systemic lupus erythematosus (SLE) patient with blurred vision and irritated right eye was referred to the ophthalmology department of our hospital. Under slit-lamp microscope, a 5.5 x 4.5 mm central corneal epithelial defect with underlying infiltrative and opaque stroma was noted in her right eye. Two weeks before, a corneal ulcer was diagnosed, and oxybuprocaine 0.05% (Lacrimin, Santen, Osaka, Japan) eye drops were prescribed 4 times daily but used every 5 to 10 minutes because the right eye was severely irritated. She was admitted immediately under the impression of toxic corneal ulcer. Preservative-free lubricants and prophylactic topical antibiotics 4 times daily were applied. Therapeutic soft contact lens was started after no infective agents were detected. Two weeks later, the stromal infiltration subsided, and the corneal epithelium was slowly healing, but superficial punctate epithelial defects at the lesion site persisted for another 6 months. The vision of her right eye improved from finger-counting at a 30-cm distance to 20/1200 with correction. CONCLUSION: Toxic keratopathy may result from abuse of topically administered anesthetics even at a very low concentration, 0.05%. Because this SLE patient has tear problems, we suggest that topical anesthetics must be used very cautiously and never prescribed to patients with dry eyes where the integrity of ocular surface is altered.

Anesthetics, Local↗

PubMed2003

Increased interleukin-6 in aqueous humor of a patient with lung-metastatic intraocular adenocarcinoma.

PURPOSE: We report increased interleukin (IL)-6 level in aqueous humor of a case of lung adenocarcinoma with metastasis to iris and anterior chamber. DESIGN: Interventional case report. METHODS: In one case and 11 healthy cataract patients as controls, we checked the levels of IL-6, IL-2, and tumor necrosis factor (TNF)-alpha in aqueous humor and serum by enzyme-linked immunosorbent assay. RESULTS: Levels of these three cytokines in serum were almost the same as with the levels in aqueous humor in the control group. The IL-6 concentrations ranged from 12.6 to 27.0 pg/ml (mean, 23.5 pg/ml) in serum and 15.0 to 43.1 pg/ml (mean, 22.4 pg/ml) in aqueous humor. There was no statistically significant difference between them. Compared with the control, the IL-6 concentration in aqueous humor of this patient, 282.0 pg/ml, increased more than 10-fold. CONCLUSION: This is a report describing elevated IL-6 level in the aqueous humor of a patient with intraocular metastasis from lung adenocarcinoma.

Adenocarcinoma↗

PubMed2003

Transforming growth factor-beta2 inhibition of corneal endothelial proliferation mediated by prostaglandin.

PURPOSE: To determine the influence of Prostaglandin (PG) E2 on transforming growth factor (TGF)-beta2-mediated inhibitory effects on the proliferation of corneal endothelial cells (CE). METHODS: The PGE2 and cell proliferation assays were performed using cultured rabbit corneal endothelium. A PGE2-specific enzyme immunoassay was used to check PGE2 synthesis in supernatants of cells cultured with and without added TGF-beta2 and/or indomethacin. To evaluate the inhibitory effects of PGE2 and TGF-beta2 on CE proliferation, the number of cells grown with exogenous PGE2, or TGF-beta2 with or without indomethacin pretreatment was determined. RESULTS: TGF-beta2, 0.5 to 50 ng/ml, increased the PGE2 secretion of CE dose-dependently in a time-dependent manner. Indomethacin (> or =0.1 microg/ml) inhibited this PGE2 secretion to a low level (around 5-10 ng/ml) in the presence or absence of exogenous TGF-beta2. Both exogenous TGF-beta2 and PGE2 inhibited CE proliferation dose-dependently over a wide range of concentrations. Indomethacin reversed the inhibitory effects of TGF-beta2 but not those of exogenous PGE2. In the medium supplemented with indomethacin, even in the presence of 50 ng/ml of TGF-beta2, CE growth did not differ from control cultures. CONCLUSIONS: TGF-beta2 stimulates PGE2 synthesis in CE and inhibits CE proliferation in a dose-dependent manner. Indomethacin extinguishes the inhibitory effects of TGF-beta2 on CE proliferation but not the effect of exogenous PGE2. These data suggest that the antiproliferative effects of TGF-beta2 on CE may be possibly due to TGF-beta2-induced synthesis of PG, most likely PGE2. SUMMARY: Inhibition of endogenous prostaglandins synthesis by indomethacin extinguished the inhibitory effects of Transforming Growth Factor-beta2 on corneal endothelium proliferation but not exogenous prostaglandin E2. It suggesting that TGF-beta2-induced autocrine synthesis of PGs, most likely PGE2, may be responsible for the anti-proliferative effects of TGF-beta2 on corneal endothelium.

Animals↗