Showing papers in "Current Eye Research in 2008"

Branch retinal vein occlusion: pathogenesis, visual prognosis, and treatment modalities

Abstract: In branch retinal vein occlusion (BRVO), abnormal arteriovenous crossing with vein compression, degenerative changes of the vessel wall and abnormal hematological factors constitute the primary mechanism of vessel occlusion. In general, BRVO has a good prognosis: 50–60% of eyes are reported to have a final visual acuity (VA) of 20/40 or better even without treatment. One important prognostic factor for final VA appears to be the initial VA. Grid laser photocoagulation is an established treatment for macular edema in a particular group of patients with BRVO, while promising results for this condition are shown by intravitreal application of steroids or new vascular endothelial growth factor inhibitors. Vitrectomy with or without arteriovenous sheathotomy combined with removal of the internal limiting membrane may improve vision in eyes with macular edema which are unresponsive to or ineligible for laser treatment.

Understanding and Analyzing Meibomian Lipids-A Review

Abstract: Purpose: This review is intended to bring to the informed reader the current state of knowledge about meibomian lipids and the art for analyzing them. Methods: At the forefront of any endeavor, there are controversies, and these, along with future directions in the field, are brought to the reader's attention. Results: Function and anatomy of meibomian glands are briefly covered, giving insight into possible mechanisms for secretory controls. Anatomically, some anomalies in meibomian gland distribution of different species, such as whales versus dolphins, are presented, and, for the first time, the structure of the meibomian glands in a selection of marsupials is presented. In attempting to make the literature more accessible, lipid structure and nomenclature are described, and these structures are related to their possible effects on the physicochemical properties of meibomian lipids. The advantages and disadvantages of various collection and storage techniques are described, as well as how gas chromatog...

Subconjunctival bevacizumab injection for corneal neovascularization in recurrent pterygium.

Abstract: Purpose: We report on the use of subconjunctival bevacizumab on corneal vessel density in recurrent pterygia.Methods: The charts of 5 patients with recurrent pterygium, who received subconjunctival injections of bevacizumab (2.5 mg/0.1 ml) were retrospectively reviewed. Ophthalmic evaluation included Snellen visual acuity (VA), tonometry and complete examination before the injection and at 1 week and 1 and 3 months thereafter. Digital photographs of the eyes were analyzed by image analysis software to determine the area of cornea covered by new vessels as a percentage of the total corneal area. Results: No ocular or systemic adverse events were observed. No change in visual acuity was noted in any patient following the injection. The mean change in corneal vascularization after one bevacizumab injection was 0.03% ± 0.45, while after two injections the change was 0.025% ± 0.19 (both not statistically different than zero, t-test). Conclusions: Short-term results suggest that subconjunctival bevacizumab is w...

Vogt-koyanagi-harada syndrome.

Abstract: Purpose: Vogt-Koyanagi-Harada syndrome is a bilateral, chronic, diffuse granulomatous panuveitis frequently associated with neurological, auditory, and integumentary manifestations. It is also one of the most common forms of uveitis among pigmented races including Chinese patients. Methods: This article reviews the current developments of Vogt-Koyanagi-Harada syndrome, including epidemiology, etiology, clinical features, observational techniques, genetics, treatment, and prognosis. Results: Increasing reports have been published to describe the clinical features of Vogt-Koyanagi-Harada syndrome in various ethnic populations from different parts of the world. In spite of tremendous progress in laboratory and clinical research, the etiology of Vogt-Koyanagi-Harada syndrome is still not completely known. Numerous studies indicate an autoimmune nature for this disease. A recent study has shown that Th17, a new subset of T cell, plays an important role in the initiation and maintenance of this disease. Early a...

In Vitro Effects of Preservative-Free Tafluprost and Preserved Latanoprost, Travoprost, and Bimatoprost in a Conjunctival Epithelial Cell Line

Abstract: Purpose: This study compared the toxicity profiles of three antiglaucoma prostaglandin F2α analogs, latanoprost, travoprost, and bimatoprost which contain benzalkonium chloride (BAK), with tafluprost, a new preservative-free prostaglandin analog. Methods: IOBA-NHC cells were exposed to BAK-containing prostanoid solutions, their respective BAK concentrations, and preservative-free tafluprost solution for 30 min. Membrane integrity, apoptosis, oxidative stress, and cells morphology were evaluated. Results: Preservative-free tafluprost resulted in significantly higher membrane integrity and lower pro-apoptotic and pro-oxidative effects than preservative-containing prostaglandin analog preparations. Conclusions: These results suggest that tafluprost, a new preservative-free prostaglandin analog, has very low or no pro-apoptotic, pro-necrotic, or pro-oxidative effects in vitro compared to preservative-containing formulations.

Topical Tacrolimus 0.03% Ointment for Intractable Allergic Conjunctivitis: An Open-Label Pilot Study

Abstract: Purpose: To evaluate the feasibility of tacrolimus 0.03% dermatological ointment (Protopic) in the treatment of intractable allergic conjunctivitis. Methods: Twenty patients (mean age 10.8 years, r...

In vivo Confocal Microscopy for the Evaluation of Corneal Microstructure in Keratoconus

Abstract: Purpose: To evaluate the corneal microstructure in keratoconus with in vivo confocal microscopy (IVCM). Methods: Unscarred corneas of 68 patients with keratoconus and 22 controls were evaluated with slit lamp examination, corneal topography, and IVCM (Confoscan 3.0, Vigonza, Italy). One eye was randomly chosen for analysis. Keratocyte, endothelial cell and basal epithelial densities, sub-basal and stromal nerve structure, and severity of stromal haze were evaluated. Results: Compared with corneas of control subjects, patients with keratoconus had a significantly lower anterior stromal keratocyte density (1279 ± 197 cells/mm2 vs. 1132 ± 178 cells/mm2, p = 0.002), lower midstromal keratocyte density (904 ± 213 cells/mm2 vs. 770 ± 120 cells/mm2, p < 0.001), lower posterior stromal keratocyte density (935 ± 113 cells/mm2 vs. 725 ± 113 cells/mm2, p < 0.001), lower endothelial cell density (2924 ± 300 cells/mm2 vs. 2719 ± 279 cells/mm2, p = 0.004), lower basal epithelial cell density (5987 ± 699 cells/mm2 vs. 4...

Experimental Assessment of Human Corneal Hysteresis

Abstract: Purpose: Hysteresis is a viscoelastic property characterized by the difference in behavior under loading and unloading. The aim of the study was to determine corneal hysteresis using experimental means. Methods: Twenty-nine human corneas with 50–95 year age were subjected to cycles of pressure loading and unloading. Two pressure application rates were adopted to approximate static and dynamic loading conditions. Results: The behavior under both loading and unloading was found to stiffen with increased age. The unloading behavior appeared to be largely independent of the pressure level at which unloading started. The difference between the behavior patterns under loading and unloading was quantified and used as a measure of corneal hysteresis. The hysteresis area was significantly larger with faster loading and with decreased age. Conclusions: The trend for hysteresis to decrease with age is in agreement with previous clinical observations. Hysteresis was also found to increase with faster pressure applica...

Analysis of macular thickness in British population using optical coherence tomography (OCT): an emphasis on interocular symmetry.

Abstract: Purpose: To evaluate macular thickness measurements in normal subjects from British origin, to assess interocular asymmetry using optical coherence tomography (OCT) and to establish standard values for macular and foveal thickness. Methods: Two hundred eyes of 100 normal individuals underwent serial scans using fast macular thickness map protocol in the Stratus OCT version 3.51, with foveal fixation. Minimum foveal thickness (MFT), central 1 mm average foveal thickness (AFT), total foveal volume (TFV) and total macular volume (TMV at 6 mm) of both eyes were assessed. The interocular asymmetry was measured and statistically analyzed. Results: The mean ± SD (N = 200) was 173 ± 23 μm for MFT and 203 ± 24 μm for AFT. The mean difference ± SD between the two eyes was (3.5 ± 14.5 μm at p = 0.17) for MFT, (6.4 ± 14.7 μm at p = 0.06) for AFT, (0.007 mm3 ± 0.007 at p = 0.06) for TFV and (0.19 ± 0.35 at p = 0.07) for TMV. Conclusion: Our study provides a normative database for macular thickness and volume parameter...

The herpes simplex virus type 1 (HSV-1) glycoprotein K(gK) is essential for viral corneal spread and neuroinvasiveness.

Abstract: Purpose: To determine the role of herpes simplex virus-1 (HSV-1) glycoprotein K(gK) in corneal infection, neuroinvasion, and virus latency in trigeminal ganglia of mice. Methods: The recombinant virus HSV-1 (McKrae) Δ gK (MKΔ gK) carrying a deletion of the gK gene was constructed by insertional/deletion mutagenesis and replaced by a gene cassette constitutively expressing the enhanced green fluorescence protein. The gK deletion of the MKΔ gK virus was rescued to produce the wild-type-like virus MKgK. Balb/c mice were infected ocularly with either virus, and the infection pattern in the eye, clinical disease progression, and establishment of viral latency was monitored. Results: Mice infected with the MKΔ gK strain produced in a gK complementing cell line did not exhibit clinical signs when compared with mice infected with the MKgK virus. Direct visualization of infected eyes revealed that the MKΔ gK virus was unable to spread in mouse corneas, while the MKgK rescued virus spread efficiently. Nineteen of 2...

Inhibitory effect of oral doxycycline on neovascularization in a rat corneal alkali burn model of angiogenesis.

Abstract: Purpose: To examine the efficacy of oral doxycycline treatment (as compared to oral and topical dexamethasone) for inhibiting corneal neovascularization (CNV). Methods: Following corneal alkali burn, rats were treated daily with oral doxycycline, oral dexamethasone, or topical dexamethasone for 14 days. Control rats were injured but were not treated. At days 3, 7, and 14 post injury, length and area of CNV were evaluated, as well as corneal epithelial healing and ulceration. Tissues were obtained from a subset of rats from each group for histopathological analysis. Results: At days 7 and 14 post-injury, CNV length in the doxycycline group was significantly less than in the untreated control (p < 0.008). The area of CNV was significantly smaller in doxycycline as compared to control rats on days 3, 7, and 14 post-injury. Inhibition of CNV (indicated by area and length) was significantly greater in both dexamethasone groups compared to the doxycycline group (p < 0.008 for all comparisons). However, epitheli...

Weekly vaccination with Copaxone (glatiramer acetate) as a potential therapy for dry age-related macular degeneration.

Abstract: Purpose: Drusen formation in age-related macular degeneration (AMD) shares some similarities with Alzheimer's disease (AD), which is associated with amyloid deposits. Aggregated beta-amyloid induces microglia to become cytotoxic and block neurogenesis. Recent evidence showed that T cell-based vaccination with Copaxone in AD mice model resulted in modulation of microglia into neuroprotective phenotype and as a result in reduction of cognitive decline, elimination of plaque formation, and induction of neuronal survival and neurogenesis. The aim was to investigate whether the effect of Copaxone on drusen in dry AMD is similar to that on deposits of other age-related chronic neurodegenerative diseases such as Alzheimer disease (AD). Materials and Methods: Patients over 50 years of age with intermediate dry AMD in both eyes were randomized to receive Copaxone or sham injections and were weekly treated by subcutaneous injections of Copaxone (dose of 20 mg) or sham injections for 12 weeks. At baseline, 6-week, a...

Formulation and Evaluation of Ciprofloxacin Hydrochloride Soluble Ocular Drug Insert

Abstract: Purpose: An attempt has been made in the present research to formulate soluble ocular inserts of ciprofloxacin hydrochloride to increase residence time and prolong drug release. Material and Methods: Drug matrices were prepared using natural polymer. Gelatin, a biodegradable polymer, was tried for the first time in the preparation of soluble ocular drug insert matrices. The inserts were then evaluated for their physicochemical parameters. The in vitro drug release studies were carried out using a bi-chambered donor receiver compartment model. In vivo drug release was carried out using rabbits as animal models. Results: Formulations CF4 and CF8, which showed controlled and prolonged in vitro drug release, were subjected to in vivo study. In vitro and in vivo correlation was found to be strong, revealing the efficacy of the formulation. Conclusion: Formulation CF8 was found promising, as it achieved the target of the present study.

Glucose-permeable interpenetrating polymer network hydrogels for corneal implant applications: a pilot study.

Abstract: Epithelialization of a keratoprosthesis requires that the implant material be sufficiently permeable to glucose. We have developed a poly(ethylene glycol)/poly(acrylic acid) (PEG/PAA) interpenetrating polymer network (IPN) hydrogel that can provide adequate passage of glucose from the aqueous humor to the epithelium in vivo. A series of PEG/PAA IPNs with varying PEG macromonomer molecular weights were synthesized and evaluated through swelling studies to determine their water content and diffusion experiments to assess their permeability to glucose. One of the PEG/PAA hydrogels prepared in this study had a glucose diffusion coefficient nearly identical to that of the human cornea (approximately 2.5 x 10(-6) cm(2)/sec). When implanted intrastromally in rabbit corneas, this hydrogel was retained and well-tolerated in 9 out of 10 cases for a period of 14 days. The retained hydrogels stayed optically clear and the epithelium remained intact and multilayered, indicating that the material facilitated glucose transport from the aqueous humor to the anterior part of the eye. The results from these experiments indicate that PEG/PAA hydrogels are promising candidates for corneal implant applications such as keratoprostheses and intracorneal lenses, and that the PEG/PAA IPN system in general is useful for creating permeable substrates for ophthalmic and other biomedical applications.

Newer emerging pathogens of ocular non-sporulating molds (NSM) identified by polymerase chain reaction (PCR)-based DNA sequencing technique targeting internal transcribed spacer (ITS) region.

Abstract: Purpose: To apply Polymerase Chain Reaction (PCR)-based DNA sequencing targeting Internal Transcribed Spacer (ITS) region for identification of non-sporulating molds (NSM) to species level which formed 12% of ocular isolates of fungi in a tertiary eye hospital in South India. Materials and Methods:Fifty ocular filamentous fungal NSM isolates recovered from 45 patients were included in the study. PCR-based DNA sequencing technique targeting ITS region was applied to identify NSM. Results: PCR-based DNA sequencing revealed 23 established pathogens involving 8 genera (Aspergillus, Fusarium, Bipolaris, Pythium, Cochilobolus, Exserohilum, Pseudoallescheria, and Scedosporiumspecies) and 27 emerging pathogens involving 7 genera (Botryosphaeria Lasiodiplodia species, Thielavia tortuosa, Glomerulla singulata, Macrophomina phaseolina, Rhizoctonia bataticola, and Podosporaspecies) reported for the first time in literature related to ocular infections. Fifteen (30%) patients with fungal keratitis caused by NSM failed...

A randomized, prospective, placebo-controlled clinical trial of a novel zinc-monocysteine compound in age-related macular degeneration.

Abstract: Purpose: To test the hypothesis that daily use of zinc-monocysteine (ZMC) supplement will be well tolerated and result in improved macular function in persons with dry age-related macular degeneration (AMD). Methods: Eligible, consenting subjects were randomized to either ZMC 25 mg or placebo twice daily for 6 months. Both ZMC and placebo groups enrolled 40 participants, with best corrected visual acuity 20/25 to 20/70, macular drusen, and pigment changes. Masked personnel determined baseline, 3- and 6-month best-corrected visual acuity, contrast sensitivity, and light flash recovery time. Differences between ZMC and placebo were analyzed by a one-sided unpaired t-test of the paired differences between baseline and 3- and 6-month timepoints for right and left eyes separately. Results: By 6 months the ZMC group showed improved visual acuity (p < 0.0001) and contrast sensitivity (p < 0.0001). Macular light flash recovery time shortened in the ZMC group at 3 months by 2.1 sec (left eye, p = 0.0001) to 3.6 se...

Oxidative stress and antioxidant activity in orbital fibroadipose tissue in Graves' ophthalmopathy.

Abstract: Purpose: To investigate the oxidative stress and antioxidant activity in the orbit in Graves' ophthalmopathy (GO). Materials and Methods: Orbital fibroadipose tissue samples were obtained from 13 cases during orbital fat decompression surgery. All cases demonstrated features of moderate or severe GO according to the European Group on Graves' Orbitopathy classification. The disease activity was evaluated with the Clinical Activity Score, and the clinical features of GO were evaluated with the Ophthalmopathy Index. Orbital fibroadipose tissue samples of 8 patients without any thyroid or autoimmune disease were studied as controls. In the tissue samples, lipid hydroperoxide level was examined to determine the level of oxidative stress; glutathione level to determine antioxidant level; superoxide dismutase, glutathione reductase, and glutathione peroxidase activities to determine antioxidant activity. Results: Lipid hydroperoxide level and all three antioxidant enzyme activities were found to be significantly...

Analysis of Autoantibodies Against Human Retinal Antigens in Sera of Patients with Glaucoma and Ocular Hypertension

Abstract: Purpose: The aim of this study was to show that complex antibody patterns against retinal antigens in sera of patients with glaucoma, found in previous studies, are autoantibodies against human antigens. Methods: Sera of 179 patients were collected at the Department of Ophthalmology (University of Mainz, Germany): non-glaucomatous control patients (n = 45), primary open-angle glaucoma (n = 45), ocular hypertension (n = 44), and normal tension glaucoma patients (n = 45). The sera were tested against Western blots of human retinal antigens. IgG antibody patterns were analyzed by multivariate statistical techniques, and some significant antigens were identified by mass spectrometry. Results: All subjects, even healthy ones, showed different and complex banding patterns. Glaucoma groups showed up- and down-regulations of antibody reactivities compared to the control group. The multivariate analysis of discriminance found significant differences (p < 0.05) in IgG antibody profiles between glaucoma groups, ocul...

The efficacy of TonoLab in detecting physiological and pharmacological changes of mouse intraocular pressure--comparison with TonoPen and microneedle manometery.

Abstract: Purpose: The efficacy of two non-invasive tonometers, TonoLab and TonoPen XL, in detecting physiological or pharmacological changes of intraocular pressure (IOP) in mouse eyes, was assessed by comparison with a microneedle method. Material and Methods: C57BL6 mice, bred under the 12-hr light and dark cycle over 2 weeks, were used. Under systemic anesthesia, mouse eyes were cannulated by a microneedle connected to a transducer and a water reservoir. We manipulated the intracameral pressure by changing the reservoir height, and obtained tonometer readings at each pressure (n = 39) with TonoLab and TonoPen XL. The correlation between each tonometer and the manometer was analyzed. Then the diurnal variation of IOP in the light and dark phases, and the IOP-lowering effect at 2 hr after latanoprost instillation, were measured with TonoLab, TonoPen XL, and a microneedle tonometer (n = 8). Results: In mouse eyes, TonoPen XL could not show reliable scores, but TonoLab readings showed a strong correlation with mano...

Multiple cytokine analysis in human tears: an optimized procedure for cytometric bead-based assay.

Abstract: Purpose: To compare instruments and reagents used for cytometric bead-based assay (CBA) of cytokines in human tears. Methods: Two CBA instruments and reagent kits from five vendors were compared in...

Natural history and histology in a rat model of laser-induced photothrombotic retinal vein occlusion.

Abstract: Purpose: To observe temporal changes in retinal physiology and histology in a rat model of laser-induced retinal vein occlusion (RVO). Methods: Ophthalmoscopy, fundus photography, and fluorescein angiography (FA) were performed following laser-induced central retinal vein occlusion (CRVO) and branch retinal vein occlusion (BRVO) immediately after laser treatment and at 3 and 6 hr and 2, 4, 7, 14, and 21 days. Retinal histology was examined at 4, 7, 14, and 21 days. Full-field electroretinogram was recorded from both eyes simultaneously at day 4. Results: For CRVO and BRVO, reperfusion of occluded branch veins was observed 1 to 2 days after treatment. Despite complete reperfusion of branch veins, retinal edema and hemorrhages peaked on day 4, and by day 14, treated retinas appeared pale and edematous upon ophthalmoscopy. In BRVO animals, retinal hemorrhages were limited to the vein-occluded region, although edema was more widespread and, to a limited extent, involved the untreated hemi-retina. Significant ...

Hyperoxia and thyroxine treatment and the relationships between reactive oxygen species generation, mitochondrial membrane potential, and cardiolipin in human lens epithelial cell cultures.

Abstract: Thyroxine-treated human lens epithelial cells, HLE B-3, were grown in either a normoxic or hyperoxic atmosphere as a first step in iden- tifying factors related to their increased viability. Reactive oxygen species, ROS, and the apparent mitochondrial membrane potential, �� m, were measured us- ing fluorescent probes. ROS were significantly higher in HLE B-3 cells grown in a hyperoxic atmosphere for both thyroxine-treated and untreated samples. However, treatment with thyroxine produced 40% lower ROS levels than un- treated cells. A mitochondrial uncoupler concomitantly reduced ROS genera- tion. In cells that were grown in a hyperoxic atmosphere, the �� m was signif- icantly higher for samples treated with thyroxine compared to those that were untreated. ROS generation correlated inversely with the apparent �� m and the amount of cardiolipin, and correlated with the amount of lipid oxidation products. These correlations were valid whether cardiolipin and the �� m were decreased as a result of oxygen or increased as a result of thyroxine treatment. Therapies that protect mitochondria from damage and reduce damaging ROS generation may potentially ameliorate the effects of oxidation that occur in aging tissues and in diseases such as cataract.

Altered Distribution of Aquaporin 5 and its C-Terminal Binding Protein in the Lacrimal Glands of a Mouse Model for Sjögren's Syndrome

Abstract: Purpose: To investigate the distribution and expression of aquaporin 5 (AQP5) and its C-terminal binding protein in the apical membrane of the lacrimal glands (LGs) in a mouse model for Sjogren's syndrome (SS). Methods: The LGs of NOD mice (mouse model for SS) and ICR mice (normal control) were homogenized and delivered into the affinity columns bound to synthetic AQP5 C-terminal peptide. The eluates were analyzed by electrophoresis and liquid chromatography mass spectrometry/mass spectrometry (LC-MS/MS) techniques.Results: AQP5 from the NOD mice exhibited the capacity to bind a 21-kDa protein that was lacking in the ICR mice. Instead, ICR mouse expressed a 17-kDa AQP5 binding protein that was absent in LGs of SS. LC-MS/MS analysis revealed these respective proteins to be major urinary protein 4 (MUP4) and prolactin-inducible protein (PIP). The treatment of ICR mice with antisense PIP oligonucleotides decreased immunostaining of AQP5 in the apical membrane. Conclusions: These observations suggest that the...

Involvement of angiotensin II-dependent vascular endothelial growth factor gene expression via NADPH oxidase in the retina in a type 2 diabetic rat model.

Abstract: Purpose: To clarify the involvement of angiotensin II-dependent vascular endothelial growth factor (VEGF) via NADPH oxidase in the retina in spontaneously diabetic Torii (SDT) rats, a type 2 diabetic rat model. In SDT rats, the plasma glucose level and angiotensin-converting enzyme (ACE) levels were measured, and effects of angiotensin II receptor blocker (ARB) and angiotensin II were also studied. Materials and Methods: We evaluated the age-dependent changes in the peripheral and ocular angiotensin II-forming systems in SDT rats at 15 (n = 8), 20 (n = 8), 30 (n = 7), and 50 weeks of age (n = 8). We also evaluated the effect of an ARB (2.5 mg/kg/day candesartan) or angiotensin II (500 ng/kg/min) on retinal gene expressions of VEGF and p22phox, a subunit of NADPH oxidase. Results: The plasma glucose level was significantly increased from 20 weeks of age. No significant changes in ACE activities in the plasma, aorta, and eye were observed until 30 weeks of age. At 50 weeks, ACE activity in the eyes was sign...

In vivo confocal microscopy of hereditary sensory and autonomic neuropathy.

Abstract: Purpose: To observe the morphology of the corneal cells and corneal nerve fibers in patients with type IV or V hereditary sensory and autonomic neuropathy (HSAN) by in vivo confocal microscopy and elucidate the mechanism leading to the loss of corneal sensation in this disease. Methods: In vivo confocal microscopy was performed on the central cornea of the right eye in 3 patients with HSAN (ages 17, 20, and 32 years), and their corneal morphology was compared with that of 3 healthy subjects (ages 28, 30, and 36 years). Corneal sensation was tested with a Cochet-Bonnet esthesiometer. Results: The superficial epithelial cell density was lower in the HSAN patients compared with the healthy subjects (1525, 1225, and 1250/mm2 vs. 2225, 1750, and 2500/mm2), but the basal epithelial cell density of the patients was similar to that of the healthy subjects. Nerve bundles were clearly observed in the sub-basal nerve plexus layer of the cornea in the healthy subjects, but were undetectable at the central cornea in t...

Transcorneal iontophoresis for delivery of ciprofloxacin hydrochloride.

Abstract: Purpose: To investigate the feasibility of utilizing iontophoresis for delivery of ciprofloxacin hydrochloride to the anterior chamber of the eye and to carry out systematic studies to investigate the effect of electrical protocol on the transcorneal drug delivery. Materials and Methods: Effect of current density (0.75 mA/cm2 to 6.25 mA/cm2 applied for 5 minutes) on drug permeation across the cornea and drug load in the cornea were investigated in vitro as well as ex vivo studies in porcine cornea model. Tolerability studies were carried out in rabbits. Cytotoxicity studies were conducted in cultured corneal tissue. Results: The drug loaded in the cornea increased with increasing current density. After 5 minutes of iontophoresis, the drug concentration in the receiver compartment fluid (in vitro) or in aqueous humor (ex vivo) was not significantly higher than control (in which electric current was not applied). However, waiting for 6–12 hours after iontophoresis for 5 minutes, the concentrations of drug i...

The Effect of Caffeine on Retrobulbar Hemodynamics

Abstract: Background: To investigate the acute effect of caffeine on intraocular pressure and retrobulbar blood flow velocity. Methods: In this randomized, double-masked, placebo-controlled, prospective study, we examined the effects of single 300-mg oral administration of caffeine on retrobulbar arteries' hemodynamics by using color Doppler ultrasonography imaging in healthy human volunteers. The subjects were divided into two groups; group 1 received a 300-mg caffeine tablet and group 2 received placebo. Measurements were obtained in two eyes at baseline, and 1 hr after acute ingestion of caffeine. Blood pressure, pulse rate, and intraocular pressure were monitored. Results: When compared with placebo, no significant change in mean blood pressure or intraocular pressure was observed after administration of caffeine. No significant differences were detected in the peak systolic and end diastolic velocities of retrobulbar arteries, compared with baseline values. Resistive index of ophthalmic, central retinal, and s...

Is there a relationship between blood pressure and intraocular pressure? An experimental study in hypertensive rats.

Abstract: Purpose: Evaluation of relation between blood pressure (BP) and intraocular pressure (IOP) in two hypertensive rat strains: spontaneously hypertensive rats (SHR) and double transgenic (dTGR) (harboring human renin and angiotensinogen genes) rats, and in their normotensive control Wistar Kyoto and Sprague Dawley rats, respectively. Methods: Each rat strain was divided into medicated and non-medicated groups. Medicated rats were treated orally with an angiotensin II receptor type 1 blocker. IOP was measured using a specific rebound tonometer and BP by a tail-cuff method. Both parameters were determined in conscious animals every second week. For comparison, at the end of the study, IOP was measured in conscious and anesthetized rats. Results: The baseline IOP was higher in hypertensive rats vs their normotensive controls. Eight weeks of treatment with an angiotensin type 1 receptor blocker did not prevent a slight increase in IOP, although it abolished the development of hypertension in SHR. The markedly el...

Carboxymethyl cellulose stimulates rabbit corneal epithelial wound healing.

Abstract: Purpose: Previously, we reported carboxymethyl cellulose (CMC) binding to human corneal epithelial cells and promoting corneal epithelial wound closure in vitro. Using an animal model, the efficacy of CMC in promoting corneal wound healing was examined. Materials and Methods: Following corneal epithelial wounding of NZ white rabbits, CMC (0.2% or 1.0%) or control vehicle (PBS) was administered topically (4 times daily for 3 days) to wounded and unwounded eyes with or without contact lens wear. Wound healing in response to the treatments was measured as percentage reduction of fluorescein-stained wound area 0 to 72 hr post-wounding. Corneas were examined histologically and expression of zonula occludens-1 (ZO-1) tight-junction was detected by immunohistochemistry. Results: Percentage wound reduction in CMC-treated groups was significantly greater than controls (p < 0.05) at 24 and 32 hr. Complete wound closure was observed by 48 hr in 100% of CMC-treated eyes compared to 45% of vehicle-treated eyes. CMC al...