Concurrence of retinitis pigmentosa and central serous retinopathy.

We describe a patient with concurrent retinitis pigmentosa and central serous chorioretinopathy. Both conditions involve dysfunction of the retinal pigment epithelium and evince distinct clinical, angiographic, and electrophysiologic features. Potential pathophysiologic connections are explored.

Vigabatrin-associated reversible MRI signal changes in patients with infantile spasms.

PURPOSE: To evaluate the magnetic resonance imaging (MRI) of pediatric patients with infantile spasms (IS) treated with vigabatrin (VGB) in order to investigate whether VGB affects the brain. METHODS: One hundred seven pediatric patients diagnosed with IS and treated with (n = 95) >or=120 mg/kg/day VGB or without (n = 12) VGB were included. MRI and diffusion-weighted imaging (DWI) were retrospectively analyzed. RESULTS: Of the patients who had MRI scans during, but not before, VGB treatment (n = 81), 25 (30.9%) exhibited abnormal MRI signal intensity and/or restricted DWI in the deep gray nuclei and brainstem. Follow-up scans (performed in 15 of the 25 patients) revealed that these changes were reversible upon withdrawal of the medication. Analysis of patients undergoing scans before, during, and after VGB treatment (n = 14) revealed that four patients had abnormal MRI signal during treatment with VBG, two of whom reversed with cessation of VGB, one reversed without cessation of VGB, and another had persistent abnormal signal while being weaned from the VGB. Patients who had not received VGB treatment (n = 12) displayed normal imaging. Younger infants (

Limiting factors to the OCT axial resolution for in-vivo imaging of human and rodent retina in the 1060 nm wavelength range.

A computational model was developed to evaluate the limitations to the highest axial resolution, achievable with ultrahigh resolution optical coherence tomography (UHROCT) in the 1060 nm wavelength region for in-vivo imaging of the human and rodent retina. The model considers parameters such as the wavelength dependent water absorption, the average length of the human and rodent eyes, and the power limitations for the imaging beam as defined in the ANSI standard. A custom-built light source with re-shaped spectrum was used to verify experimentally the results from the computational model. Axial OCT resolution of 4.2 microm and 7.7 microm was measured from a mirror reflection with the custom light source by propagating the imaging beam through water cells with 5 mm and 25 mm thickness, corresponding to the average axial length of the rodent and human eye respectively. Assuming an average refractive index of 1.38 for retinal tissue, the expected axial OCT resolution in the rodent and human retina is 3 microm and 5.7 microm respectively. Retinal tomograms acquired in-vivo from the rat eye with the modified light source show clear visualization of all intraretinal layers, as well as a network of capillaries (approximately 10 microm in diameter) in the inner- and outer plexiform layers of the retina.

In vitro assessment of medical device toxicity: interactions of benzalkonium chloride with silicone-containing and p-hema-containing hydrogel contact lens materials.

PURPOSE: To analyze the interactions of benzalkonium chloride (BAK) with silicone-containing (lotrafilcon A and galyfilcon A) and p-HEMA-containing (etafilcon A and vifilcon A) hydrogel contact lenses and to examine the possibility of using sodium fluorescein permeability assay (SFPA), 3-(4,5-dimethylthiazol- 2-yl)-2,5-diphenyltetrazolium bromide (MTT) assay and the bovine lens assay in conjunction with confocal laser scanning microscopy (CLSM) as a battery of in vitro alternatives to evaluate the potential toxicity of soft contact lenses. METHODS: Four soft contact lens types (Focus Monthly [vifilcon A], Focus NIGHT & DAY [lotrafilcon A], ACUVUE Advance With Hydraclear [galyfilcon A], and SUREVUE [etafilcon A]) were soaked for 24 hours in various concentrations of BAK (1%, 0.1%, 0.01%, and 0.001%) in 20-mL glass vials. After 24 hours, the lenses were gently washed in Hanks' Balanced Salt Solution (HBSS), placed in 5 mL of HBSS, and incubated for a total of 7 days at 37 degrees C, 5% CO2. BAK released into HBSS (i.e., the extract) was recovered from the vials and used as the test chemical in the SFPA (epithelium integrity), MTT assay (cellular viability), and the bovine lens assay with CLSM (mitochondrial metabolism and optical properties). The amount of BAK extracted from the various contact lenses was measured using an Abbe refractometer. Negative controls consisted of HBSS and contact lenses subjected to the same conditions as the treated contact lenses, but without BAK. RESULTS: Extracts obtained from soaking Focus Monthly lenses in BAK caused the most damage to the epithelium and mitochondrial metabolism. However, at 0.1% BAK extraction, all lens extracts showed increased levels of back vertex distance variability of the cultured bovine lens. CONCLUSIONS: Unexpectedly, lenses extracted with HBSS showed SFPA and MTT assay responses and an observed effect on the bovine lens epithelium visualized by CLSM, indicating that unknown chemical agents may be leached from contact lens polymers.