From stem cell niche environments to engineering of corneal epithelium tissue.

Studies on stem cells (SC) show that SC functions are determined by the extracellular microenvironment, known as the "niche", and by intrinsic genetic programs in the SCs; both are involved in regulating the delicate balance of self-renewal and differentiation. We have identified an animal model of limbal SC (LSC) deficiency and transplantation of SC-containing limbal tissue to treat the LSC deficiency, which could not only replace LSCs by providing new healthy corneal epithelial cells but also restore the lost niche of the limbal stromal layer, causing the regression of vessels and rearrangement of the corneal stromal lamellae. The purpose of the ex-vivo expansion technique is to develop a method that will enable culture of a small number of SCs which could than be expanded in a defined cultured system while preserving the original characteristics and properties of the SCs.

Changes in corneal basal epithelial phenotypes in an altered basement membrane.

Background: To examine the corneal epithelial phenotype in an altered basement membrane.

Methodology/principal Findings: Corneas from 9 patients with symptoms of continuous unstable corneal curvature (CUCC) were harvested by penetrating keratoplasty and subjected to histology examination and immunohistochemical staining with transactivating and N-terminally truncated pP63 transcript (ΔNp63), cytokeratin 3 (Krt3), ATP-binding cassette sub-family G member 2 (ABCG2), connexin 43 (CX43), p38 mitogen-activated protein kinases (p38MAPK), activating protein 2 (TFAP2), and extracellular signal-regulated kinase (Erk1/2) monoclonal antibodies. Positive immunostaining with ABCG2, p38MAPK, and TFAP2 monoclonal antibodies was observed in the basal epithelial cells of CUCC patients, and CX43 and ΔNp63 were detected in the full-thickness epithelial cells of CUCC patients.

Ex vivo expansion of corneal stem cells on amniotic membrane and their outcome.

Objectives: To identify the stem-cell property of the ex vivo expansion of limbal stem cells (LSCs) on amniotic membrane (AM) in culture system and after clinical transplantation.

Methods: Four key factors have to be performed in the defined culture system: (1) the label-retaining cells have to be identified; (2) the cells can be serially expanded and passaged in vitro; (3) the expanded cells can be labeled by tissue-specific keratin or markers, and (3) their stem cells cannot be labeled by those keratin or markers.

Results: The ex vivo-expanded LSCs on AM were positive for p63 and ABCG2 and BrdU label-retaining studies on flat mount preparation.

Effects of aging on anterior and posterior corneal astigmatism.

Purpose: To evaluate age-related changes in astigmatism of both corneal surfaces and the whole cornea.

Methods: The right eyes of 370 subjects were measured with a rotating Scheimpflug camera (Pentacam). Astigmatisms of the anterior and posterior corneal surfaces were determined.

Estimation accuracy of surgically induced astigmatism on the cornea when neglecting the posterior corneal surface measurement.

Purpose: To evaluate the accuracy of corneal surgically induced astigmatism (SIA) estimation when neglecting the posterior corneal surface measurement.

Methods: Fifty right eyes undergoing phacoemulsification were measured with a rotating Scheimpflug camera (Pentacam; Oculus Inc., Wetzlar, Germany) both before and after surgery.

Estimation of the effective lens position using a rotating Scheimpflug camera.

Purpose: To describe a no-history method of estimating the effective lens position (ELP) for double-K intraocular lens (IOL) power calculation in eyes that had previous refractive surgery.

Setting: Departments of Ophthalmology, Taipei Medical University Hospital and Taipei City Hospital, Taipei, Taiwan.

Methods: The corneal height (H(m)) and anterior chamber diameter (AG(m)) in 106 unoperated eyes were measured using a rotating Scheimpflug camera.

Intraocular lens power calculation after automated lamellar keratoplasty for high myopia.

Purpose: To report intraocular lens (IOL) power calculation in 2 eyes that were highly undercorrected by previous myopic automated lamellar keratoplasty (ALK).

Methods: A 35-year-old man underwent bilateral myopic ALK, which caused high residual myopia (-9.0 -4.

Seasonal variations in the occurrence of retinal vein occlusion: a five-year nationwide population-based study from Taiwan.

Purpose: To determine whether seasonal variation exists in the incidence of retinal vein occlusion.

Design: Retrospective, nationwide population-based administrative database study.

Methods: We collected data on outpatient and emergency visits for the period from January 1999 through December 2003 from the Taiwan National Health Insurance Research Database, a source that covers more than 96% of Taiwan's 23 million citizens.

Validity of the keratometric index: evaluation by the Pentacam rotating Scheimpflug camera.

Purpose: To determine the keratometric index based on actual measurements of the anterior and posterior corneal surfaces using a rotating Scheimpflug camera (Pentacam, Oculus) and evaluate the accuracy of this keratometric index in estimating total and posterior corneal powers.

Setting: Departments of Ophthalmology, Taipei Medical University Hospital and Taipei City Hospital, Taipei, Taiwan.

Methods: The right eye of 221 subjects was measured with the Pentacam system.

Reduction of indocyanine green-associated photosensitizing toxicity in retinal pigment epithelium by sodium elimination.

Objective: To determine if eliminating sodium affects indocyanine green (ICG) photosensitizing toxicity and uptake in cultured human retinal pigment epithelial (RPE) cells.

Methods: Cultured human RPE cells were exposed to ICG (2.5 mg/mL) in balanced salt solution and sodium-free balanced salt solution for 2 minutes.

Annual database of intraocular lens power in a Taiwanese population.

Background: To derive a unique database of intraocular lens (IOL) power for Taiwanese, an ethnic group with a strikingly high prevalence of myopia.

Methods: A retrospective series of 3068 cases visiting Chang Gung Memorial Hospital, Linkou for cataract removal and posterior chamber IOL implantation between July 1999 and June 2000 was reviewed. The distribution of IOL powers and a possible age-correspondence was analyzed by one-way analysis of variance (ANOVA) test and multiple regression.

GDNF gene therapy attenuates retinal ischemic injuries in rats.

Purpose: To examine the protective effects of glial cell line-derived neurotrophic factor (GDNF) on retinal ischemia-reperfusion injury by using gene delivery.

Methods: Gene delivery to retinal cells was achieved through intravitreal injections of recombinant adeno-associated virus expressing GDNF (rAAV-GDNF) in the right eyes and AAV expressing Escherichia coli LacZ (rAAV-LacZ) in the left eyes of Sprague-Dawley rats. Ischemic injury was introduced three weeks after gene delivery.

Ultrasound biomicroscopy in pigmented conjunctival cystic nevi.

Purpose: To report the use of ultrasound biomicroscopy in the clinical diagnosis and management of pigmented conjunctival cystic nevi.

Method: Two patients, aged 11 and 18 years, with rapidly growing raised conjunctival melanocytic lesions suspected to be inflamed juvenile conjunctival nevus underwent ultrasound biomicroscopic and histopathologic examinations.

Results: Ultrasound biomicroscopic examination of the lesions revealed multiple areas of cystic tissue, which is compatible with pathologic finding of compound nevus with epithelial inclusion cysts formation.

Cytotoxicity of indocyanine green on retinal pigment epithelium: implications for macular hole surgery.

Objective: To evaluate the potential cytotoxic effects of indocyanine green (ICG) on cultured human retinal pigment epithelium (RPE) and the resultant implications for macular hole surgery.

Methods: Human RPE cells were exposed to ICG in concentrations from 0.001 to 5 mg/mL.

Expression of tissue inhibitor of metalloproteinase-4 in normal human corneal cells and experimental corneal neovascularization.

Purpose: To study the expression of TIMP-4 in cultured corneal cells and in corneal neovascularization.

Methods: Human limbo-corneal epithelial cells, fibroblasts, and endothelial cells were cultured in serum-free, PMA- or basic fibroblast growth factor (bFGF)-treated condition. Neovascularization in rat cornea was induced by suturing.

Functional MRI of amblyopia before and after levodopa.

Functional magnetic resonance imaging (fMRI) was applied to five older amblyopes with monocular amblyopia before and after levodopa treatment. During the experiment, images were acquired in two runs with visual stimulation delivered through the sound and the amblyopic eyes, respectively. The experiment was performed on each of the subjects, before and after their oral administration of levodopa/carbidopa (0.

Gene therapy for detached retina by adeno-associated virus vector expressing glial cell line-derived neurotrophic factor.

Purpose: To examine the protective effect of glial cell line-derived neurotrophic factor (GDNF) on retinal detachment (RD)-induced photoreceptor damage by using gene delivery.

Methods: Gene delivery to photoreceptors was achieved by subretinal injection of recombinant adeno-associated virus expressing GDNF (rAAV-GDNF) in the right eyes and AAV expressing Escherichia coli LacZ (rAAV-LacZ) in the left eyes of Lewis rats. RD in bilateral eyes was induced with subretinal injection of high-density vitreous substitute in the temporal retina 3 weeks after gene delivery.

Acanthamoeba keratitis presenting as dendritic keratitis in a soft contact lens wearer.

Acanthamoeba keratitis is a rare cause of corneal infection in Taiwan, which can result in devastating visual outcomes. A 37-year-old woman, who wore soft contact lenses, suffered from severe pain in her left eye. Biomicroscopy revealed dendritic keratitis, radial keratoneuritis, and fine keratic precipitates on her cornea.

Amniotic membrane transplantation for pseudomonal keratitis with impending perforation.

Background: To determine whether amniotic membrane transplantation (AMT) can be used as adjunctive therapy to promote wound healing and prevent perforation in bacterial keratitis caused by Pseudomonas aeruginosa.

Methods: We report on 6 eyes from 6 patients with bacterial keratitis caused by Pseudomonas aeruginosa associated with prominent stromal melting and extensive stromal loss. AMT was performed after treatment with fortified antibiotics for at least 1 week.

High-density vitreous substitute in the management of advanced Coats' disease.

Advanced Coats' disease is a threat to vision. Management of advanced Coats' disease has long been a challenge to ophthalmologists. Some people have attempted to use pars plana vitrectomy and intraocular diathermy on diseased vessels followed by intraocular gas or silicone oil injection.

Amniotic membrane graft for the management of scleral melting and corneal perforation in recalcitrant infectious scleral and corneoscleral ulcers.

Purpose: To study the efficacy and safety of using cryopreserved human amniotic membrane (AM) graft as a patch graft to reduce stromal melting and promote reepithelialization in extensive infectious scleral and corneoscleral ulcers.

Methods: Four cases of infectious scleral ulcers with persistent scleral melting and no sign of reepithelialization and three cases of corneoscleral ulcers with corneal perforation were studied. All patients had previously undergone pterygium excision, and infections were caused by Pseudomonas (n = 4), fungi (n = 2), and atypical Mycobacterium (n = 1).

Inducible adeno-associated virus vector-delivered transgene expression in corneal endothelium.

Purpose: To investigate whether recombinant adeno-associated virus (rAAV) vector--mediated transgene expression is induced by inflammation in corneal endothelial cells in vivo.

Methods: The ocular anterior chamber of New Zealand White rabbits was injected with rAAV-LacZ (10(7) units of infection). Transient ocular anterior segment inflammation was induced by an intravitreal injection of lipopolysaccharide (LPS).