Plasma polymer surface modified expanded polytetrafluoroethylene promotes epithelial monolayer formation in vitro and can be transplanted into the dystrophic rat subretinal space.

The aim of this study was to evaluate whether the surface modification of expanded polytetrafluoroethylene (ePTFE) using an n-heptylamine (HA) plasma polymer would allow for functional epithelial monolayer formation suitable for subretinal transplant into a non-dystrophic rat model. Freshly isolated iris pigment epithelial (IPE) cells from two rat strains (Long Evans [LE] and Dark Agouti [DA]) were seeded onto HA, fibronectin-coated n-heptylamine modified (F-HA) and unmodified ePFTE and fibronectin-coated tissue culture (F-TCPS) substrates. Both F-HA ePTFE and F-TCPS substrates enabled functional monolayer formation with both strains of rat. Without fibronectin coating, only LE IPE formed a monolayer on HA-treated ePTFE. Functional assessment of both IPE strains on F-HA ePTFE demonstrated uptake of POS that increased significantly with time that was greater than control F-TCPS. Surgical optimization using Healon GV and mixtures of Healon GV: phosphate buffered saline (PBS) to induce retinal detachment demonstrated that only Healon GV:PBS allowed F-HA ePTFE substrates to be successfully transplanted into the subretinal space of Royal College of Surgeons rats, where they remained flat beneath the neural retina for up to 4 weeks. No apparent substrate-induced inflammatory response was observed by fundus microscopy or immunohistochemical analysis, indicating the potential of this substrate for future clinical applications.

The incidental findings of age-related macular degeneration during diabetic retinopathy screening.

BACKGROUND: The purpose of this study was to determine the reliability of detecting age-related macular degeneration (AMD) during screening for diabetic retinopathy (DR). METHODS: This prospective study included 2,003 subjects with diabetes mellitus who underwent photographic screening for DR. The reliability of detecting AMD lesions was tested by interobserver and intraobserver agreement, and the sensitivity and specificity of diagnosing AMD at different grades of severity were tested using the consensus grading of a group as the reference standard. RESULTS: DR affected 24.7% of the subjects. The age-standardized prevalence of early AMD was 17.9%, and late AMD was 0.1%. The interobserver and intraobserver agreement for grading AMD was substantial (k = 0.72 and 0.71 respectively, p < 0.001). It was equally good in those with different severities of DR. There was also no difference in sensitivity and specificity of detecting AMD in those with different levels of DR (sensitivity 62-68% and specificity 97-98%). CONCLUSION: Intermediate- and high-risk AMD that warrant treatment with zinc and anti-oxidant supplements could be reliably detected during screening for diabetic retinopathy.

Screening for diabetic retinopathy with or without a copayment in a randomized controlled trial: influence of the inverse care law.

OBJECTIVE: To examine whether the inverse care law operates in a screening program for diabetic retinopathy (DR) based on fee for service in Hong Kong. DESIGN: Randomized controlled trial. PARTICIPANTS: All those with type 1 or 2 diabetes from 2 clinics were recruited. INTERVENTION: Diabetic retinopathy screening with a small copayment versus free access in a publicly funded family medicine service. MAIN OUTCOME MEASURES: Uptake of screening and severity of DR detected. Association between these outcome variables and independent variables were determined using multivariate logistic regression models and reported as odds ratios (ORs). RESULTS: After randomization, 1387 subjects in the free group and 1379 subjects in the pay group were eligible for screening, and 94.9% (1316/1387) and 92.6% (1277/1379), respectively, agreed to participate in the study. The offer of screening was accepted by 94.8% (1247/1316) in the free group and 91.2% (1164/1277) in the pay group, and the final uptake ratios were 88.5% (1165/1316) and 82.4% (1052/1277), respectively (Pearson chi = 19.74, P<0.001). Being in the pay group was associated with a lower uptake of screening than being in the free group (OR, 0.59; confidence interval [CI], 0.47-0.74) and a lower detection rate of DR (OR, 0.73; CI, 0.60-0.90) after adjustment for potential confounding factors. Subjects with higher socioeconomic status were more likely to attend screening and had a lower prevalence of DR detected. CONCLUSIONS: The inverse care law seems to operate in a preventive intervention when a relatively small copayment is applied. There is a case for making effective preventive services free of charge. FINANCIAL DISCLOSURE(S): The author(s) have no proprietary or commercial interest in any materials discussed in this article.

Neuroprotective effects of lutein in a rat model of retinal detachment.

BACKGROUND: Retinal detachment (RD) is a leading cause of blindness, and although final surgical re-attachment rate has greatly improved, visual outcome in many macula-off detachments is disappointing, mainly because of photoreceptor cell death. We previously showed that lutein is anti-apoptotic in rodent models of ischemia/reperfusion injury. The objective of this study is to investigate lutein as a possible pharmacological adjunct to surgery. METHODS: Subretinal injections of 1.4 % sodium hyaluronate were used to induce RD in Sprague-Dawley rats until their retinae were approximately 70 % detached. Daily injections of corn oil (control group) or 0.5 mg/kg lutein in corn oil (treatment group) were given intraperitoneally starting 4 h after RD induction. Animals were euthanized 3 days and 30 days after RD and their retinae were analyzed for photoreceptor apoptosis and cell survival at the outer nuclear layer (ONL) using TUNEL staining and cell counting on retinal sections. Glial fibrillary acidic protein (GFAP) and rhodopsin (RHO) expression were evaluated with immunohistochemistry. Western blotting was done with antibodies against cleaved caspase-3, cleaved caspase-8 and cleaved caspase-9 to delineate lutein's mechanism of action in the apoptotic cascade. To seek a possible therapeutic time window, the same set of experiments was repeated with treatment commencing 36 h after RD. RESULTS: When lutein was given 4 h after RD, there were significantly fewer TUNEL-positive cells in ONL 3 days after RD when compared with the vehicle group. Cell counting showed that there were significantly more nuclei in ONL in lutein-treated retinae by day 30. Treatment groups also showed significantly reduced GFAP immunoreactivity and preserved RHO expression. At day 3 after RD, Western blotting showed reduced expression of cleaved caspase-3 and cleaved caspase-8 in the treatment group. No difference was found for cleaved caspase-9. When lutein was given 36 h after RD similar results were observed. CONCLUSIONS: Our results suggest that lutein is a potent neuroprotective agent that can salvage photoreceptors in rats with RD, with a therapeutic window of at least 36 h. The use of lutein in patients with RD may serve as an adjunct to surgery to improve visual outcomes.

Choroidal thickness in relation to hypercholesterolemia on enhanced depth imaging optical coherence tomography.

PURPOSE: To investigate the relationship of hypercholesterolemia and choroidal thickness in normal healthy volunteers. METHOD: This was a cross-sectional observational study. Volunteers with no ocular abnormalities were examined using enhanced depth imaging optical coherence tomography. Choroidal and retinal thicknesses were measured at the fovea, and at 4 different locations 1 mm superior, inferior, temporal, and nasal to the fovea. Subjects were further divided into those with hypercholesterolemia (Group 1) and normal control subjects (Group 2) for subgroup analysis regarding the effect of hypercholesterolemia on choroidal thickness. Subjects with hypertension and diabetes were excluded. RESULTS: A total of 322 eyes of 161 subjects were studied. Mean age was 59.9 years (range, 24-84 years). The mean subfoveal choroidal thickness was 261 ± 98.7 µm. Mean subfoveal choroidal thickness negatively correlated with age (r = -0.326; P = 0.001). The mean serum total cholesterol was 5.02 ± 0.98 mmol/L. In Group 1, it was 5.65 ± 1.15 mmol/L, while in Group 2, it was 4.72 ± 0.73 mmol/L. The difference was statistically significant (P = 0.003). Subjects in Group 1 tended to be older and have worse vision, although the difference did not reach statistical significance. The mean subfoveal choroidal thickness in Group 1 was 306 ± 111 µm, while that in Group 2 was 258 ± 97 µm. The difference was statistically significant (P = 0.041). The same difference was also found at the 1 mm nasal (P = 0.041) and 1 mm superior (P = 0.040). CONCLUSION: The subfoveal choroidal thickness was found to be significantly higher in subjects with hypercholesterolemia. This has to be taken into account when analyzing choroidal thickness.

Lectin from Agaricus bisporus inhibited S phase cell population and Akt phosphorylation in human RPE cells.

PURPOSE: Lectin from the edible mushroom Agaricus bisporus (ABL) was found to inhibit cell proliferation of some ocular and cancer cell lines. To elucidate how ABL inhibited RPE cell proliferation, we investigated the changes in cell cycle distribution and cell proliferation-related signaling pathways after ABL treatment. METHODS: Primary human RPE cells were isolated and grown in DMEM/F12 with or without the ABL (20 or 90 µg/mL) for 3 days. Analysis of cell cycle was performed by flow cytometry. Phosphorylation status of Erk, Jnk, p38, and Akt as well as p53 expression levels were investigated by Western blotting. The role of phosphorylated-Akt in RPE cell proliferation was further evaluated using LY294002. RESULTS: After ABL treatment (90 µg/mL), the amount of cells present in the S phase was found to be reduced. These changes were not apparent in cells treated with 20 µg/mL ABL. In addition, Erk and Akt were found to be hyperphosphorylated and hypophosphorylated, respectively. The expression levels of phosphorylated-Jnk, phosphorylated-p38, and p53 were not altered when compared with those of the control cells. When RPE cells were treated with LY294002 and deprived from phosphorylated-Akt expression, cell proliferation rate was reduced. Reduction in the amount of cells present in S phase was also observed. CONCLUSIONS: Our results showed that ABL hypophosphorylated Akt and this observation is in line with the fact that ABL attenuates cell proliferation. As the level of p53 was not significantly altered by ABL, this indicated that ABL-arrested cell cycle progression was independent of p53 activation.

The inner segment/outer segment junction: what have we learnt so far?

PURPOSE OF REVIEW: The advancement of optical coherence tomography has improved the resolution of in-vivo images of the retina. This has led to a wealth of novel knowledge regarding the microstructures of the photoreceptor layer and its relationship with visual functions under different pathological diseases. RECENT FINDINGS: Identification of the hyperreflective lines in the photoreceptor layer has been made possible by spectral domain optical coherence tomography. The inner segment/outer segment junction, external limiting membrane, cone outer segment tips, and the retinal pigment epithelium were thought to be the origins of the four hyperreflective lines seen in the photoreceptor layer. Integrity of these lines has been linked with visual functions in various retinopathies, and has been suggested to carry prognostic implications. Recovery of initially interrupted lines has been documented following successful treatment. SUMMARY: Identification of these hyperreflective lines may have clinical implications as visual function was found to correlate closely with their integrity. Restoration of these lines may indicate treatment response and potential visual recovery.

Tissue tropism of swine influenza viruses and reassortants in ex vivo cultures of the human respiratory tract and conjunctiva.

The 2009 pandemic influenza H1N1 (H1N1pdm) virus was generated by reassortment of swine influenza viruses of different lineages. This was the first influenza pandemic to emerge in over 4 decades and the first to occur after the realization that influenza pandemics arise from influenza viruses of animals. In order to understand the biological determinants of pandemic emergence, it is relevant to compare the tropism of different lineages of swine influenza viruses and reassortants derived from them with that of 2009 pandemic H1N1 (H1N1pdm) and seasonal influenza H1N1 viruses in ex vivo cultures of the human nasopharynx, bronchus, alveoli, and conjunctiva. We hypothesized that virus which can transmit efficiently between humans replicated well in the human upper airways. As previously reported, H1N1pdm and seasonal H1N1 viruses replicated efficiently in the nasopharyngeal, bronchial, and alveolar epithelium. In contrast, representative viruses from the classical swine (CS) (H1N1) lineage could not infect human respiratory epithelium; Eurasian avian-like swine (EA) (H1N1) viruses only infected alveolar epithelium and North American triple-reassortant (TRIG) viruses only infected the bronchial epithelium albeit inefficiently. Interestingly, a naturally occurring triple-reassortant swine virus, A/SW/HK/915/04 (H1N2), with a matrix gene segment of EA swine derivation (i.e., differing from H1N1pdm only in lacking a neuraminidase [NA] gene of EA derivation) readily infected and replicated in human nasopharyngeal and bronchial epithelia but not in the lung. A recombinant sw915 with the NA from H1N1pdm retained its tropism for the bronchus and acquired additional replication competence for alveolar epithelium. In contrast to H1N1pdm, none of the swine viruses tested nor seasonal H1N1 had tropism in human conjunctiva. Recombinant viruses generated by swapping the surface proteins (hemagglutinin and NA) of H1N1pdm and seasonal H1N1 virus demonstrated that these two gene segments together are key determinants of conjunctival tropism. Overall, these findings suggest that ex vivo cultures of the human respiratory tract provide a useful biological model for assessing the human health risk of swine influenza viruses.

Enhanced depth imaging optical coherence tomography.

Imaging the choroid with conventional commercial spectral-domain optical coherence tomography (SD-OCT) has been difficult, mainly because of difficulty in signal transmission beyond the retinal pigment epithelium. A recent modification to the standard technique, termed enhanced depth imaging optical coherence tomography (EDI-OCT), was able to image the choroid with reasonable clarity using commercial SD-OCTs. The aim of this article was to review the technique, principle, recent findings, and possible future developments regarding EDI-OCT. A MEDLINE search on all published articles on EDI-OCT was performed up to December 2010. The principle behind EDI-OCT was discussed. Modification to the conventional technique in image acquisition was described and illustrated with figures. EDI-OCT findings in various retinal and choroidal diseases were discussed. Advantages and disadvantages were also discussed. EDI-OCT has proved to be a promising novel technique in imaging the choroid.

Tropism and innate host responses of the 2009 pandemic H1N1 influenza virus in ex vivo and in vitro cultures of human conjunctiva and respiratory tract.

The novel pandemic influenza H1N1 (H1N1pdm) virus of swine origin causes mild disease but occasionally leads to acute respiratory distress syndrome and death. It is important to understand the pathogenesis of this new disease in humans. We compared the virus tropism and host-responses elicited by pandemic H1N1pdm and seasonal H1N1 influenza viruses in ex vivo cultures of human conjunctiva, nasopharynx, bronchus, and lung, as well as in vitro cultures of human nasopharyngeal, bronchial, and alveolar epithelial cells. We found comparable replication and host-responses in seasonal and pandemic H1N1 viruses. However, pandemic H1N1pdm virus differs from seasonal H1N1 influenza virus in its ability to replicate in human conjunctiva, suggesting subtle differences in its receptor-binding profile and highlighting the potential role of the conjunctiva as an additional route of infection with H1N1pdm. A greater viral replication competence in bronchial epithelium at 33 degrees C may also contribute to the slight increase in virulence of the pandemic influenza virus. In contrast with highly pathogenic influenza H5N1 virus, pandemic H1N1pdm does not differ from seasonal influenza virus in its intrinsic capacity for cytokine dysregulation. Collectively, these results suggest that pandemic H1N1pdm virus differs in modest but subtle ways from seasonal H1N1 virus in its intrinsic virulence for humans, which is in accord with the epidemiology of the pandemic to date. These findings are therefore relevant for understanding transmission and therapy.

Simultaneous spectral domain OCT and fundus autofluorescence imaging of the macula and microperimetric correspondence after successful repair of rhegmatogenous retinal detachment.

BACKGROUND/AIMS: To evaluate the ultrastructural changes in the macula after successful repair of rhegmatogenous retinal detachment (RRD) using simultaneous spectral domain optical coherence tomography (sdOCT) and fundus autofluorescence (FAF) imaging and to perform functional correlations with microperimetry. METHODS: Simultaneous sdOCT and FAF imaging were performed using a combined sdOCT-confocal scanning laser ophthalmoscope (cSLO) system. Microperimetry was performed in a subgroup of these patients. RESULTS: 17 patients with macular-on RRD and 20 with macular-off RRD were recruited. sdOCT images revealed disruption of the external limiting membrane, inner segment/outer segment junction or the Verhoeff membrane in 16 eyes (43.2%). The presence of any or more of these disruptions was significantly associated with a poor postoperative best-corrected visual acuity (BCVA) (p<0.001). Patients with abnormal FAF were also associated with poor postoperative BCVA (p<0.001). However, there was a generally poor correspondence between the localisation of ultrastructural abnormalities as detected by sdOCT and FAF changes. Areas of decreased microperimetric sensitivity corresponded well with the ultrastructural changes and abnormal FAF. CONCLUSIONS: FAF changes may lag behind ultrastructural changes in the OCT, some of which may reverse with the passage of time. The present study demonstrates the ultrastructural changes assessed with simultaneous FAF and sdOCT and their relation with visual outcome.

Correlation between microaneurysms and retinal thickness in diabetic macular edema.

PURPOSE: Microaneurysms commonly are believed to be related causally to retinal thickening in diabetic retinopathy, especially by leaking. The hypothesis that thicker areas of retina in diabetic retinopathy have more microaneurysms per unit area than areas that are not as thick was tested. METHODS: Retinal thickness analysis was performed with a prototype instrument for 27 eyes of 27 diabetic patients and 22 normal eyes of 22 healthy subjects. Maps of retinal thickness were created, and microaneurysms were counted in zones having four levels of retinal thickness. RESULTS: There was no increase in either total microaneurysms or apparent leaking microaneurysms per unit area with increasing levels of retinal thickness (P = 0.77 and 0.87, respectively). CONCLUSION: Some microaneurysms may not cause thickening, or other factors may contribute to retinal thickening in diabetic retinopathy. The results may have implications on the pathogenesis of diabetic macular edema.

Emulsification and inverted hypopyon formation of oxane HD in the anterior chamber.

BACKGROUND: Oxane HD(R) is a "heavier-than-water" silicone oil which has a specific gravity of 1.02 g/cm(3). When dispersed into droplets, one expects them to sink. We report a case of emulsification of Oxane HD in an eye that unexpectedly manifested as an "inverted hypopyon". METHODS: The clinical findings of a 45-year-old man who underwent pars plana vitrectomy and Oxane HD endotamponade for a phakic inferior rhegmatogenous retinal detachment are described. RESULTS: A large silicone oil globule was noted to be floating in the anterior chamber on postoperative day 1. Emulsification of the globule and inverted hypopyon formation were subsequently observed at 2 months postoperatively. CONCLUSIONS: Emulsification and inverted hypopyon formation in the anterior chamber may occur with Oxane HD. One explanation might be that the Oxane HD has separated out into its constituent components of silicone and RMN3, which raises questions as to the basis for its claim to be a heavier-than-water tamponade.

Retinal redetachment after silicone oil removal in proliferative vitreoretinopathy: a prognostic factor analysis.

PURPOSE: To determine the prognostic factors associated with retinal redetachment after 1300-centistokes silicone oil removal in rhegmatogenous retinal detachments (RDs) associated with grade C proliferative vitreoretinopathy (PVR). DESIGN: Nonrandomized, retrospective, comparative interventional trial. METHODS: One hundred and forty-seven eyes with RD and grade C PVR treated with silicone oil tamponade, with subsequent silicone oil removal, in an institutional setting. Main outcome measures included anatomic success, defined as complete retinal attachment after silicone oil removal, and best-corrected visual acuity (BCVA) after silicone oil removal. RESULTS: Silicone oil was removed after a mean tamponade period of 12.4+/-9.8 months. The mean follow-up after silicone oil removal was 22.1+/-18.7 months (range, 6.0 to 71.0 months). The retina remained attached in 120 eyes after oil removal. The overall anatomic success rate was 81.6%+/-3.2%. Logistic regression showed that an increased number of previous unsuccessful RD surgeries (odds ratio [OR], 0.39; 95% confidence interval [CI], 0.19 to 0.80; P=.010) and longer axial lengths (OR, 0.42; 95% CI, 0.15 to 0.87; P=.032) were associated with a lower anatomic success rate. Previous vitrectomy, previous scleral buckling procedure, 12% perfluoropropane-air exchange immediately after silicone oil removal, and duration of silicone oil tamponade were not statistically associated with the anatomic success rate. Anatomic success was associated with a significantly better BCVA (1.169+/-0.475 vs 1.520+/-0.381 logarithm of the minimum angle of resolution; P<.001). CONCLUSIONS: The number of previous surgeries and axial length, rather than the nature of the previous surgical procedures, were significant prognostic factors for anatomic success after silicone oil removal.

Differential aqueous and vitreous concentrations of moxifloxacin and ofloxacin after topical administration one hour before vitrectomy.

PURPOSE: To investigate the penetration of ofloxacin and moxifloxacin into the aqueous and vitreous after topical administration one hour before vitrectomy surgery. DESIGN: Prospective, randomized, double-blind case series study. METHODS: Twenty-seven patients undergoing vitrectomy were randomized to receive either topical ofloxacin 0.3% or moxifloxacin 0.5% every 10 minutes for one hour before surgery. Aqueous and vitreous samples were obtained and analyzed using high-performance liquidation chromatography. RESULTS: The moxifloxacin aqueous (1.576 +/- 0.745 microg/ml) and vitreous (0.225 +/- 0.013 microg/ml) levels were significantly higher than the ofloxacin aqueous (0.816 +/- 0.504 microg/ml) (P = .0009) and vitreous (0.225 +/- 0.013 microg/ml) [P = .0054] levels, respectively. The mean moxifloxacin aqueous and vitreous levels exceeded the minimum inhibitory concentration for 90% of isolates (MIC(90)) for a wide variety of bacteria implicated in endophthalmitis. In contrast, the aqueous level of ofloxacin exceeded the MIC(90) of only a few organisms. CONCLUSIONS: Moxifloxacin applied every 10 minutes during the hour before vitrectomy penetrated the eye significantly better than ofloxacin.