The Relationship between Corvis ST Tonometry Measured Corneal Parameters and Intraocular Pressure, Corneal Thickness and Corneal Curvature.

The purpose of the study was to investigate the correlation between Corneal Visualization Scheimpflug Technology (Corvis ST tonometry: CST) parameters and various other ocular parameters, including intraocular pressure (IOP) with Goldmann applanation tonometry. IOP with Goldmann applanation tonometry (IOP-G), central corneal thickness (CCT), axial length (AL), corneal curvature, and CST parameters were measured in 94 eyes of 94 normal subjects. The relationship between ten CST parameters against age, gender, IOP-G, AL, CST-determined CCT and average corneal curvature was investigated using linear modeling. In addition, the relationship between IOP-G versus CST-determined CCT, AL, and other CST parameters was also investigated using linear modeling. Linear modeling showed that the CST measurement 'A time-1' is dependent on IOP-G, age, AL, and average corneal curvature; 'A length-1' depends on age and average corneal curvature; 'A velocity-1' depends on IOP-G and AL; 'A time-2' depends on IOP-G, age, and AL; 'A length-2' depends on CCT; 'A velocity-2' depends on IOP-G, age, AL, CCT, and average corneal curvature; 'peak distance' depends on gender; 'maximum deformation amplitude' depends on IOP-G, age, and AL. In the optimal model for IOP-G, A time-1, A velocity-1, and highest concavity curvature, but not CCT, were selected as the most important explanatory variables. In conclusion, many CST parameters were not significantly related to CCT, but IOP usually was a significant predictor, suggesting that an adjustment should be made to improve their usefulness for clinical investigations. It was also suggested CST parameters were more influential for IOP-G than CCT and average corneal curvature.

Intraocular pressure readings obtained through soft contact lenses using four types of tonometer.

PURPOSE: To compare the reliability and accuracy of intraocular pressure (IOP) measured while wearing soft contact lenses (SCLs) using a non-contact tonometer (NCT), Goldmann applanation tonometer (GAT), iCare rebound tonometer (RBT) and the Tono-Pen XL. METHODS: Twenty-six healthy subjects were examined. The IOP was measured using NCT, GAT, RBT, and the Tono-Pen XL, while the subjects wore SCLs -5.00 D, -0.50 D and +5.00 D. Bland-Altman plots and a regression analysis were used to compare the IOPs obtained with those instruments and the IOPs of the naked eyes measured using GAT (the standard IOPs in this study). RESULTS: The IOPs obtained by the Tono-Pen XL while the subjects were wearing -5.00 D, -0.50 D, and +5.00 D SCLs were significantly higher than those of the naked eyes obtained using GAT. RBT showed that the IOPs were similar to the GAT standard IOPs under all conditions. The IOPs measured with NCT and GAT while the subjects were wearing -5.00 D and -0.50 D SCLs were similar to the GAT standard IOPs. The IOPs obtained with RBT and NCT while the subjects were wearing -5.00 D and -0.50 D SCLs exhibited a good correlation with the standard IOPs. CONCLUSION: The NCT and RBT are best when measuring IOP through hydrogel SCLs.

Comparison of the toxicity profile of benzalkonium chloride-preserved tafluprost and SofZia-preserved travoprost applied to the ocular surface.

PURPOSE: To evaluate some clinically important features of benzalkonium chloride (BAK) toxicity by comparing tafluprost with 0.001% BAK and travoprost preserved with SofZia applied to the ocular surface of the eyes with glaucoma. METHODS: This was a prospective, randomized, observer unmasked, multicenter crossover trial. A total of 195 patients were randomized and 174 patients completed the study at 19 clinics between November 2011 and August 2012. Topical BAK-preserved tafluprost or SofZia-preserved travoprost was newly administered or continued. Superficial punctate keratopathy (SPK), tear break-up time (BUT), the conjunctival hyperemia score, and intraocular pressure (IOP) were compared at the baseline visit, 4, and 12 weeks after the start of therapy. The eye drops were switched to another eye drop after 12 weeks of observation. RESULTS: The total SPK and conjunctival hyperemia scores were significantly lower in the tafluprost compared with those in the travoprost phase (both P=0.038). There were no significant differences in the SPK scores of the superior area (P=0.679), central area (P=0.089), inferior area (P=0.090), and tear BUT (P=0.271). The IOP-lowering effects were similar (P=0.155). CONCLUSIONS: SPK, hyperemia score, and tear BUT while using tafluprost with 0.001% BAK were not inferior compared with those caused by travoprost with SofZia.

Ocular surface displacement with and without contact lenses during non-contact tonometry.

PURPOSE: To evaluate the displacement of the central ocular surface during non-contact tonometry with and without soft contact lenses and determine the factors associated with the displacement of the central ocular surface and intraocular pressure (IOP) reading changes caused by wearing soft contact lenses (CLs). METHODS: One eye each in 21 subjects was studied. The cornea was photographed using a high-speed camera at 5,000 frames/sec during non-contact tonometry without contact lenses (NCL), with -5.0 diopters (D), -0.5 D and +5.0 D CL. The displacement of the ocular surface and the factors affecting displacement at the IOP reading and maximum displacement time were investigated. RESULTS: The IOP readings while wearing +5 D CL were significantly higher than those obtained while wearing -5 D CL. The ocular surface displacement between +5 D CL and other groups were significantly different. A significant positive correlation was found between the ocular surface displacement of subjects at the IOP reading time and the IOP obtained with the non-contact tonometer. A significant negative correlation was found between the ocular surface curvature and the IOP obtained using the non-contact tonometer. The radius of curvature of the ocular surface affected the displacement during the IOP reading and maximum displacement time. CONCLUSIONS: Our results indicate that soft contact lens use changes the ocular surface behavior and IOP readings during non-contact tonometry. The radius of curvature of the eye affects the ocular surface displacement and IOP readings in this situation.

Width of abnormal ganglion cell complex area determined using optical coherence tomography to predict glaucoma.

PURPOSES: We examined the relationships of ganglion cell complex (GCC) parameters determined on spectral-domain optical coherence tomography (SD-OCT), especially the width of abnormal areas, and its ability to detect various stages of glaucoma. METHODS: OCT parameters of glaucomatous and normal eyes were determined with the RTVue SD-OCT. Widths of abnormal GCC areas marked by either red or yellow on the OCT significance map were quantified with image J software. The relationships between the abnormal GCC area and other GCC parameters [thickness, focal loss volume (FLV), and global loss volume (GLV)] and the peripapillary retinal nerve fiber layer (RNFL) thickness were determined using regression analyses. The potential of using the GCC and RNFL parameters to discriminate between glaucomatous and normal eyes was examined using the area under the curve (AUC) of receiver operating characteristics (ROC). RESULTS: One hundred and eighteen glaucomatous eyes and 45 normal control eyes were studied. Nonlinear models best described the relationships between abnormal GCC area and other GCC parameters. Scatter plots showed changes in the average thickness of the GCC and RNFL, and the average sizes of the GLV preceded changes of abnormal areas of the GCC. The width of the abnormal areas on the GCC thickness map was comparable with other parameters for diagnosing glaucoma. CONCLUSIONS: OCT thickness parameters appeared to decrease faster than the area parameter at the initial stage of glaucoma. The sizes of abnormal areas of the GCC were the most pertinent parameters for detecting glaucoma.

Inner retinal layer comparisons of eyes with exudative age-related macular degeneration and eyes with age-related macular degeneration and glaucoma.

BACKGROUND: The incidence of glaucoma increases with age, as does age-related macular degeneration (AMD), with the reported incidence of glaucoma among AMD subjects being 5.4 %. Optical coherence tomography (OCT) can detect glaucomatous changes in the inner retina with high sensitivity. The purpose of this study was to compare ganglion cell complex (GCC) parameters and the thickness of the peripapillary retinal nerve fiber layer (RNFL) in normal eyes to that observed in eyes with age-related macular degeneration (AMD) and eyes with both AMD and glaucoma. METHODS: The GCC components [GCC thickness, focal loss volume (FLV), and global loss volume (GLV)] and peripapillary RNFL thickness were measured using RTVue spectral-domain OCT (SD-OCT). The GCC and RNFL parameters of normal eyes, AMD eyes treated with different types of therapy, and AMD eyes with and without glaucoma were evaluated using nonparametric tests. Univariate and multivariate analyses were used to determine whether the GCC and RNFL parameters could be used to differentiate AMD eyes with glaucoma from those without glaucoma. RESULTS: Seventy-one normal eyes, 120 eyes with AMD, and 23 eyes with AMD and glaucoma were studied. The values of all GCC components were significantly different in the normal eyes from those observed in the eyes with AMD, except for the RNFL thicknesses. The GCC and RNFL parameters were not significantly different between the eyes receiving different types of therapy among the AMD groups. The RNFL thickness was significantly correlated with glaucoma diagnosis in AMD eyes. CONCLUSIONS: These findings indicate that there is damage to the inner retinal layers in eyes with AMD. The RNFL thickness can be a useful parameter for differentiating eyes with AMD from eyes with both AMD and glaucoma.

Platelet-derived growth factor receptor alpha is associated with oxidative stress-induced retinal cell death.

PURPOSE: The purpose of this study was to investigate the role played by platelet-derived growth factor-α (PDGFRα) in oxidative stress-induced retinal cell death. A previous proteomic study from our laboratory showed that expression of PDGFRα is elevated considerably in the retinas of an animal model of glaucoma-the excitatory amino acid carrier (EAAC) 1-deficient (EAAC1-/-) mouse. METHODS: Retinal sites and expression patterns of PDGFRα were determined by immunohistochemistry in the retinas of EAAC1-/- and control CRL:CD1(ICR) mice. A retinal cell line was exposed to hydrogen peroxide, and expression PDGFRα determined by Western blot analysis. Effects of PDGF-AA and PDGFRα-siRNA on hydrogen peroxide-induced retinal cell death were examined. RESULTS: PDGFRα was detected in the retinal ganglion cell layer (RGL) of both EAAC1-/- and ICR mice, and was also localized in the internal nuclear layer (INL) of EAAC1-/- mice. While treatment with excess PDGF-AA had no additional effect on retinal cell death, expression of PDGFRα increased with exposure to hydrogen peroxide. Hydrogen peroxide-induced retinal cell death was inhibited by exposure to PDGF-AA via phosphatidylinositol 3 kinase (PI3K); cell death was promoted by PDGFRα-siRNA. CONCLUSIONS: PDGFRα is expressed in mouse retina, where it is essential for retinal cell survival under conditions of oxidative stress.

Cullin5 reduces retinal cell death induced by glutamate toxicity.

PURPOSE: To investigate the expression in the mouse retina and the function in a retinal cell of cullin5 that is known as a protein that is associated with ubiquitilation. METHODS: The retinal sites of expressing cullin5 were determined by immunohistochemistry with a specific antibody for cullin5. Retinal cells were transfected with HA-tagged cullin5 using an adenovirus system, and retinal cells were exposed to L-glutamate with or without an over-expression of cullin5. RESULTS: Cullin5 was expressed in the retina of C57BL/6N mice and the retinal ganglion cell layer (RGL) of retina was strongly immunostained. Further, cullin5 was localized in the retinal ganglion cell (RGC). An over-expression of cullin5 reduced the percentage of retinal cell deaths induced by L-glutamate. CONCLUSIONS: The expression of cullin5 on retinal cells and reduction in the percentage of dead retinal cells induced by L-glutamate suggest that cullin5 has neuroprotective properties in retinal cells.