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To determine the discriminant function of optical coherence tomography angiography (OCTA) by disease severity in glaucoma.In this prospective, observational cross-sectional study, all subjects underwent visual fields, retinal nerve fiber layer (RNFL) measurements, and OCTA imaging. Local fractal analysis was applied to OCTA images (radial peripapillary capillaries [RPC] layer). Vessel density en face and inside the disc and spacing between large and small vessels were quantified. Stepwise logistic regression was performed and a glaucoma severity score (range, 0-1: 0, normal; 1, severe glaucoma) was developed by using global and regional (superotemporal [ST], inferotemporal [IT], temporal, superonasal [SN], inferonasal, and nasal) vascular parameters. Glaucoma severity score was compared with visual field and RNFL indices.One hundred ninety-nine eyes (112 subjects) with glaucoma (28 eyes preperimetric; 83 early, 43 moderate, and 45 severe glaucoma) and 74 normal (54 subjects) eyes were enrolled. Preperimetric and glaucomatous eyes had significantly altered (P0.001) global vascular parameters as compared to normal; regionally, ST, then SN and IT sectors (in that order) showed more change in glaucomatous eyes. Vascular parameters showed better discriminant ability (area under the curve [AUC], sensitivity, and specificity of 0.70, 69.2%, and 72.9%, respectively) than structural parameters between normal and preperimetric glaucomatous eyes. Vascular parameters had comparable AUC (P0.05) to visual fields for perimetric glaucoma. Glaucoma severity score identified preperimetric glaucoma and early glaucoma better than did visual fields.Vascular parameters could be a useful adjunct tool to evaluate/diagnose glaucoma. Longitudinal studies are needed to determine their use in early detection and prognostication.

Purpose To quantitatively evaluate microdistortions in Bowman's layer and change in corneal stiffness after small incision lenticule extraction (SMILE). Methods This was a prospective, longitudinal, and interventional study. Thirty eyes of 30 patients were screened preoperatively and underwent SMILE for treatment of myopia with astigmatism. Visual acuity, refraction, optical coherence tomography (OCT; Bioptigen, Inc., Morrisville, NC) imaging of the layer and air-puff applanation (Corvis-ST, OCULUS Optikgeräte Gmbh, Germany) was performed before and after surgery (1 day, 1 week, and 1 month). The Bowman's Roughness Index (BRI) was defined as the enclosed area between the actual and an ideal smooth layer to quantify the microdistortions. A viscoelastic model was used to quantify the change in corneal stiffness using applanation. Results Uncorrected distance visual acuity improved (P < 0.001) and refractive error decreased (P < 0.0001) after SMILE. BRI increased from preoperative levels (1.81 × 10−3 mm2) to 1 week (3.14 × 10−3 mm2) after SMILE (P < 0.05) and then decreased up to a month (2.43 × 10−3 mm2; P < 0.05). Increase in the magnitude of the index correlated positively with refractive error (P = 0.02). However, corneal stiffness reduced after SMILE (105.86 ± 1.4 N/m versus 97.97 ± 1.21 N/m at 1 month, P = 0.001). The decrease in corneal stiffness did not correlate with refractive error (P = 0.61). Conclusions BRI correlated positively the magnitude of refractive error. However, decrease in corneal stiffness, assessed by air-puff applanation, may not be related to microdistortions after SMILE. Translational Relevance An objective method of quantification of Bowman's layer microdistortions using OCT was developed to monitor corneal wound healing and improve lenticule extraction methods.

Purpose To evaluate corneal air-puff deformation responses and ocular geometry as predictors of Marfan syndrome. Design Prospective observational clinical study. Methods Sixteen investigator-derived, 4 standard Ocular Response Analyzer (ORA), and geometric variables from corneal tomography and optical biometry using Oculus Pentacam and IOL Master were assessed for discriminative value in Marfan syndrome, measuring right eyes of 24 control and 13 Marfan syndrome subjects. Area under the receiver operating characteristic (AUROC) curve was assessed in univariate and multivariate analyses. Results Six investigator-derived ORA variables successfully discriminated Marfan syndrome. The best lone disease predictor was Concavity Min (Marfan syndrome 47.5 ± 20, control 69 ± 14, P = .003; AUROC = 0.80). Corneal hysteresis (CH) and corneal resistance factor (CRF) were decreased (Marfan syndrome CH 9.45 ± 1.62, control CH 11.24 ± 1.21, P = .01; Marfan syndrome CRF 9.77 ± 1.65, control CRF 11.03 ± 1.72, P = .01) and corneas were flatter in Marfan syndrome (Marfan syndrome K mean 41.25 ± 2.09 diopter, control K mean 42.70 ± 1.81 diopter, P = .046). No significant differences were observed in central corneal thickness, axial eye length, or intraocular pressure. A multivariate regression model incorporating corneal curvature and hysteresis loop area (HLA) provided the best predictive value for Marfan syndrome (AUROC = 0.85). Conclusions This study describes novel biodynamic features of corneal deformation responses in Marfan syndrome, including increased deformation, decreased bending resistance, and decreased energy dissipation capacity. A predictive model incorporating HLA and corneal curvature shows greatest potential for noninvasive clinical diagnosis of Marfan syndrome.

Poverty is one of the main issues in India, attracting the attention of sociologists, economists and political class equally. Government of India has been running many poverty-alleviation programmes and some success also achieved in this endeavour over the years. However, even today Governments struggle with mass level of poverty and related problems. Amidst great hype and hope, Indian parliament passed a revolutionary novel and unique Act i.e. National Rural Employment Guarantee Act (NREGA) in 2005. Various institutions and individuals have documented the processes of revival and resurgence largely driven by the MGNREGA as an axis of struggle by the rural poor. It has neither been claimed nor was envisaged that that MGNREGA is the key to successful rej uvenation of rural areas of the country that have remained marginalized in the growth process of the country. Study on MGNREGA in Meghalaya is lacking, so therefore the present study was taken with the two objectives. 1. To evaluate the impact of MGNREGA on assets of the beneficiaries. 2. To evaluate the impact of MGNREGA on house construction of the beneficiaries. The primary data was collected from East Khasi Hills district of Meghalaya with pre-structured interview schedule. The study revealed that there was an increase in the number of households acquiring cell phones by 31.67 per cent after MGNREGA due to the increase in income. The number of households having television sets have increased by 8.33 per cent after working in MGNREGA and the number of households having radio sets have decreased by 1.67 per cent. On the basis of equality of income pertaining to both the beneficiaries and non-beneficiaries, the possession of assets like farm implements, television sets, radio, cell phones, poultry and pig is seen to have its advantage for the beneficiaries. With the introduction of the scheme the beneficiaries also have the advantage of house construction, repairing and extension which has increased by 50 per cent in the number of households after the scheme as compared prior to the scheme. It was evident from the findings that the rural households in the East Khasi Hills district of Meghalaya have been benefited from MGNREGA in many ways as it has increased their purchasing power resulting in multiple impacts in their social and economic life; however there is still a long way to fulfill the purpose and objectives of MGNREGA and ensure the livelihood security of the rural and tribal households.

PURPOSE. Corneal collagen cross-linking (CXL) is a method for modifying the natural history of keratoconus and other corneal ectatic diseases. The authors evaluated the use of collagenase for generating an experimental model of ectasia to evaluate the topographic effects of CXL interventions. METHODS. Nine human corneoscleral specimens unsuitable for transplantation were used. After epithelial debridement, mounting, and pressurization on an artificial anterior chamber, a solution of 10 mg/mL collagenase type II with 15% dextran was applied to five corneas for three hours. Three of these corneas subsequently underwent riboflavin/UV-A CXL. Scheimpflug-based tomography was performed before collagenase exposure, after collagenase exposure, and after CXL to evaluate changes in maximum axial curvature of the anterior surface (Kmax) at three IOP levels. Results were compared to four control eyes exposed to dextran alone. RESULTS. A statistically significant increase in Kmax was seen across all IOP levels in the collagenase group compared to the control group (þ6.6 6 1.1 diopters [D] and þ0.3 6 0.8 D, respectively, at physiological IOP). After CXL, Kmax decreased (� 7.6 6 2.0 D at physiological IOP). Anterior corneal aberrations increased after collagenase exposure and decreased after CXL. Light microscopy showed loss of normal stromal collagen architecture and localized edema after collagenase exposure. CONCLUSIONS. A method for generating topographic features of corneal ectasia in human tissue is demonstrated. No significant sensitivity of Kmax to IOP was observed. CXL caused regression of steepening and induced aberrations in this model, consistent with clinical trends. The model may be useful for testing modifications to standard CXL techniques. (Invest Ophthalmol

Keratoconus (KC) is a disease that is characterized clinically by a region of abnormally high curvature, reduced corneal thickness, and progressive corneal topographic irregularity.1,2 Tensile testing of corneal strips cut from KC keratoplasty buttons has also demonstrated 50% to 60% reductions in the strain-dependent corneal elastic modulus relative to normal cadaveric tissue.3,4 These findings, taken with some of the classic clinical signs of KC, such as corneal stress lines (Vogt striae) and rupture of Descemet's membrane (hydrops), support the concept of biomechanical failure as a central pathologic feature of the disease. Although the interactions of genetic,5,6 biochemical,7,8 and ultrastructural9,10 abnormalities that ultimately contribute to material instability and corneal deformation under the ocular loading forces are complex, we propose that differential biomechanical weakening in the area of the cone is a common pathway through which these biological factors influence corneal shape. By corollary, we propose that topographic progression of KC can be simulated as a progressive focal reduction in material elastic modulus without an absolute requirement for specific knowledge of the genetic, biochemical, and ultrastructural processes that contribute to ongoing material failure. Corneal collagen cross-linking (CXL) is a relatively new tissue-sparing technique for the treatment of KC.11–16 In this technique, a photosensitizing agent containing riboflavin is applied to the corneal surface at regular time intervals for a total time of 30 minutes followed by continuous application of a broad ultraviolet (UV-A) beam for another 30 minutes.11,13,15 Before riboflavin is applied, the epithelium is typically removed from the central 5- to 9-mm-diameter zone of the cornea to facilitate penetration of riboflavin into the stroma.11,13,15 Wollensak et al.16 reported a nearly 3.5 fold increase in Young's modulus of human corneas after CXL ex vivo. Histology and optical coherence tomography (OCT) suggest that the morphologic and optical changes associated with CXL are typically restricted to a depth of 200 to 300 μm from the anterior surface with an irradiance of 3 mW/cm2.14,16,17 In addition to the intended curvature-stabilizing effects of CXL, unexpected reductions in steep corneal curvature and improvements in uncorrected and corrected distance visual acuity have been reported.11,13 A recent clinical study has also suggested that optical outcomes in the central cornea can differ significantly after CXL, depending on the location of the cone (defined as the locus of maximum tangential curvature) relative to the optic axis.15 The finite element model (FEM) can be a useful tool for providing insight into the effects of such material property alterations on the geometry and optical performance of the cornea. A small number of studies have explored the effect of corneal thinning and elastic modulus reduction in KC.18–20 However, these studies have not accounted for major clinical features of KC such as astigmatism and higher order aberrations, nor have they incorporated patient-specific clinical tomography. No previous study has attempted to model the effects of CXL on KC. We recently analyzed the effect of variations in overall corneal elastic modulus in a two-dimensional whole-eye model of myopic laser in situ keratomileusis (LASIK) and demonstrated a greater tendency toward biomechanical steepening of the central cornea (and residual myopia) in a model with weaker hyperelastic corneal properties.21 Conversely, an otherwise identical model with a stiffer cornea demonstrated a greater tendency toward central corneal flattening due to a redistribution of strain from the central to the peripheral cornea. Although the model assumed a uniform stiffening of the entire cornea, the results suggested a potential biomechanical mechanism for the reduction of corneal steepening observed in many patients treated with CXL.21 The purposes of this study were (1) to develop a method for three-dimensional modeling of KC progression and for modeling the effects of corneal collagen stiffening, (2) to evaluate changes in curvature and optical aberrations of the anterior surface of the KC cornea as a function of magnitude and depth of corneal stiffening, and (3) to compare model results to clinical topographic observations of curvature reduction. Finally, the study also evaluated novel CXL approaches employing reduced treatment diameters centered on the steepest topographic point. During the course of these studies, we hypothesized that a smaller, focal treatment centered on the topographic cone might provide enhanced flattening effects and more favorable changes in higher order aberrations. A smaller treatment zone may expose the patient to less treatment risk by virtue of a smaller epithelial defect with less chance of persistence, associated haze,22,23 and UV exposure of the corneal endothelium, limbal stem cells, and intraocular tissues. We also modeled the effect of introducing a spatially graded treatment (which is feasible clinically with a modified ultraviolet intensity profile) incorporating a less abrupt radial transition of elastic properties than might be expected from a more uniform ultraviolet exposure. As a substrate for the model, this study uses data from four clinical corneal tomography scans: (1) two eyes from an asymmetric KC patient whose less-affected eye is progressed to a state resembling the more severely affected eye via simulated changes in elastic properties and corneal thickness and (2) two KC eyes with different cone loci to assess differences in the response to CXL as a function of cone location and depth of CXL.

The purpose of this study is to develop a 3D patient-specific finite element model (FEM) of the cornea and sclera to compare predicted and in vivo refractive outcomes and to estimate the corneal elastic property changes associated with each procedure. Both eyes of a patient who underwent laser-assisted in situ keratomileusis (LASIK) for myopic astigmatism were modeled. Pre- and postoperative Scheimpflug anterior and posterior corneal elevation maps were imported into a 3D corneo-scleral FEM with an unrestrained limbus. Preoperative corneal hyperelastic properties were chosen to account for meridional anisotropy. Inverse FEM was used to determine the undeformed corneal state that produced

PURPOSE—To compare changes in corneal hysteresis (CH) and the corneal resistance factor (CRF) in myopic and hyperopic laser in situ keratomileusis (LASIK) and evaluate their relationship with the number of photoablative pulses delivered, a surrogate for ablation volume. SETTING—Cleveland Clinic Cole Eye Institute, Cleveland, Ohio, USA. METHODS—Preoperative and 1-week postoperative Ocular Response Analyzer measurements in eyes that had femtosecond-assisted LASIK were studied retrospectively. Changes in CH and CRF were compared and tested for correlation with the number of excimer laser pulses. RESULTS—Thirteen myopic eyes and 11 hyperopic eyes were evaluated. Preoperative corneal thickness, CH, CRF, programmed correction magnitude, flap thickness, and total number of fixed spot-size photoablative pulses were similar in the 2 groups (P>.1). Decreases in CH and CRF were greater after myopic LASIK than after hyperopic LASIK (P

Summary India is considered to have a low incidence of HIV infection so far. Nevertheless, an epidemic of HIV infection has been reported recently among intra-venous drug users (IVDUs) in Manipur, a north-eastern state of India, bordering Myanmar (Burma). This report describes the epidemiology of intravenous drug abuse in the state of Manipur. Four hundred and fifty IVDUs were interviewed. Their age (median 24 years) and sex patterns (95 % male) differ from those reported from western countries. It is estimated that there may be approximately 15000 such addicts in a population of 1·8 million and 50% of them could be positive for HIV. Knowledge of AIDS and its transmission is significantly higher among the addicts than non-addict controls. Free availability of heroin was found to be the major factor responsible for the high rate of addiction. It is presumed that two other neighbouring States which are well-connected to Manipur and also have a common border with Myanmar (part of the ‘Golden Triangle’) may have a similar problem with HIV infection.

Venous stenosis is a significant problem in arteriovenous fistulae, likely due to anatomical configuration and wall shear stress profiles. To identify linkages between wall shear stress and the magnitude and pattern of vascular stenosis, we produced curved and straight fistulae in a pig model. A complete wall stress profile was calculated for the curved configuration and correlated with luminal stenosis. Computer modeling techniques were then used to derive a wall shear stress profile for the straight arteriovenous fistula. Differences in the wall shear stress profile of the curved and straight fistula were then related to histological findings. There was a marked inverse correlation between the magnitude of wall shear stress within different regions of the curved arteriovenous fistula and luminal stenosis in these same regions. There were also significantly greater differences in wall shear stress between the outer and inner walls of the straight as compared to curved arteriovenous fistula, which translated into a more eccentric histological pattern of intima-media thickening. Our results suggest a clear linkage between anatomical configuration, wall shear stress profiles, and the pattern of luminal stenosis and intima-media thickening in a pig model of arteriovenous fistula stenosis. These results suggest that fistula failure could be reduced by using computer modeling prior to surgical placement to alter the anatomical and, consequently, the wall shear stress profiles in an arteriovenous fistula.

Purpose: To investigate the impact of corneal elasticity on corneal shape changes before and after simulated LASIK with and without consideration of whole-eye biomechanics. Methods: A finite element whole-eye model of a human eye was constructed. The cornea was modeled as hyper-elastic and incompressible using experimental data representing a range of corneal stiffness. The corneal response to intraocular pressure loading and LASIK for 2.00, 4.00, and 6.00 diopters of spherical myopia was analyzed as a function of corneal stiffness and limbal boundary conditions. Results: Myopic LASIK produced different degrees of central flattening and postoperative ametropia in low-stiffness and high-stiffness corneas. Although a cornea-only model demonstrated maximum stresses and displacements in the central cornea and predicted residual myopia, a whole-eye model with equivalent corneal stiffness predicted greater paracentral displacements and less myopic undercorrection. In a whole-eye model with a stiffer cornea, maximum displacements shifted further toward the limbus, favoring additional mechanically mediated central flattening and refractive overcorrection (hyperopia). In postoperative LASIK models thinned by high myopic corrections, corneal stiffening caused central cornea flattening. Conclusions: Differences in the corneoscleral stiffness relationship affect simulated refractive outcomes after LASIK and may be a source of individual variation in refractive surgery outcomes. A whole-eye model allowing limbal motion illustrates a stiffness-dependent biomechanical balance between central corneal flattening and pre-ectatic weakening of the corneal apex not demonstrated in previous computational models and provides insight into under- and overcorrection in myopic LASIK and the previously unexplained phenomenon of corneal flattening after therapeutic collagen cross-linking for keratoconus. [ J Refract Surg . 2009;25:875–887.]

Coronary circulation is mainly regulated by two serial resistances, namely, epicardial stenosis and microvascular impairments, both causing abnormal coronary blood circulation [1]. Delineation of the true severities of these diseases is important to guide clinical decision-making processes for the selection of appropriate treatment procedures [2]. The presently used diagnostic parameters: FFR (fractional flow reserve defined as the ratio of distal to proximal hyperemic pressure) and CFR (coronary flow reserve defined as ratio of basal to hyperemic flow) [1], for the evaluation of severity of epicardial coronary stenosis are well established in clinical practice. On the other hand, current methods to evaluate the microcirculatory status are limited [3].

To evaluate a novel Zernike algorithm to differentiate 3-dimensional (3-D) corneal thickness distribution of corneas with keratoconus (KC) from normal corneas.A retrospective development and evaluation of a diagnostic approach.Corneal tomography with Scheimpflug imaging was performed in normal (43 eyes) and KC (85 eyes) corneas. Axial and tangential cone location magnitude index (axial CLMI and tangential CLMI, respectively) of the anterior and posterior surface were calculated. The aberrations of the anterior corneal surface were analyzed with Zernike polynomials. Pachymetric Zernike analyses (PZA) were used to map the 3-D thickness distribution of the cornea. Logistic regression was performed to develop a diagnostic procedure for KC using CLMI, PZA, and aberrations. A receiver operating characteristic curve was constructed for each regression model. Corneal volume was also compared between normal and KC corneas. Only the central 5 mm zone was used for all analyses.Among the PZA coefficients, second- and third-order root mean squares of PZA coefficients were the best predictors of KC corneas (P.0001). Among the CLMI variables, axial CLMI of anterior and tangential CLMI of posterior surface were the best predictors of KC (P.0001). Among the Zernike corneal aberration coefficients, second- and third-order root mean squares of coefficients were the best predictors of KC (P.0001). Sensitivity and specificity of Zernike corneal aberrations, CLMI, and PZA logistic regression model were similar (P.05).The entire 3-D corneal thickness was mapped with Zernike. The PZA method was comparable to CLMI and anterior corneal wavefront aberrations in detecting KC.

Objective: To study the correlation and effect of sequential measurement of intraocular pressure (IOP) with Goldmann applanation tonometer (GAT), ocular response analyzer (ORA), dynamic contour tonometer (DCT), and Corvis ST. Setting and Design: Observational cross-sectional series from the comprehensive clinic of a tertiary eye care center seen during December 2012. Methods: One hundred and twenty-five study eyes of 125 patients with normal IOP and biomechanical properties underwent IOP measurement on GAT, DCT, ORA, and Corvis ST; in four different sequences. Patients with high refractive errors, recent surgeries, glaucoma, and corneal disorders were excluded so as to rule out patients with evident altered corneal biomechanics. Statistical Analysis: Linear regression and Bland-Altman using MedCalc software. Results: Multivariate analysis of variance with repeated measures showed no influence of sequence of device use on IOP (P = 0.85). Linear regression r 2 between GAT and Corvis ST, Corvis ST and Goldmann-correlated IOP (IOPg), and DCT and Corvis ST were 0.37 (P = 0.675), 0.63 (P = 0.607), and 0.19 (P = 0.708), respectively. The Bland-Altman agreement of Corvis ST with GAT, corneal compensated IOP, and IOPg was 2 mmHg (−5.0 to + 10.3), −0.5 mmHg (−8.1 to 7.1), and 0.5 mmHg (−6.2 to 7.1), respectively. Intraclass correlation coefficient for repeatability ranged from 0.81 to 0.96. Conclusions: Correlation between Corvis ST and ORA was found to be good and not so with GAT. However, agreement between the devices was statistically insignificant, and no influence of sequence was observed.

Percutaneous coronary transluminal angioplasty (PTCA) is an interventional procedure most widely used to revascularize diseased coronary vessels. Since its inception in 1964, modern-day PTCA involves the use of cutting edge devices that have vastly improved the usefulness of this procedure, with minimal damage to coronary vessels such as left anterior descending, left circumflex, and right coronary arteries. In this article, the authors give an overview of key devices and instruments that have become synonymous with coronary angioplasty. Additionally, the authors present a summary of their past work on coronary diagnostics using customized guidewires, a key component of coronary angioplasty. Guidewires are commonly used to measure two hemodynamic indices, myocardial fractional flow reserve and coronary flow reserve, to evaluate the degree of success achieved in opening up a diseased (or blocked) coronary vessel. However, the presence of guidewire introduces an additional flow obstruction effect, which necessitates that some correction be applied to myocardial fractional flow reserve and coronary flow reserve. This process would enable estimation of true severity of coronary lesion, and its possible treatment using PTCA. This article provides these corrections through simple correlations that could be useful for diagnosis of focal coronary lesions under clinical settings. Keywords: PTCA; guidewire; guiding catheter; balloon catheter; vessel closure device

Simultaneous measurement of pressure and flow rate has been found to be helpful in evaluating the physiologic significance of obstructive coronary artery disease and in the diagnosis of microvascular disease. This experimental study seeks to find important pressure-flow relationship in an in-vitro model of significant coronary artery stenoses using a non-Newtonian liquid, similar to blood showing a shear thinning behavior, using significant stenotic in-vitro model (minimal area stenosis = 90%). The geometry for the stenotic model is based on data provided in an in vivo study by Wilson et al., (1988). For 90% area stenosis, the maximum recorded pressure drop for steady flow rate of 55, 79 and 89 are 14, ~24 and ~32 mmHg respectively. The maximum pressure drop at flow rate of 115 ml/min (the physiological limit) is 50.3 mmHg respectively. Using a power law curve fit, the maximum pressure drop (in mmHg) related with flow rate (in ml/min) provided a power law index of 1.72. Shorter distal length than required in the in-vitro model did not allow the recording of complete pressure recovery. This preliminary data provides reference values for further experimentation both in vitro with pulsatile flow as in physiological conditions, and in vivo.Copyright © 2004 by ASME

It is important to know the drug distribution following administration of drug in order to properly treat with adequate dosage and thus, avoid damage to tissues due to excessive high concentrations. A computer model was developed to determine drug distribution by convective-diffusive transport processes in a rabbit eye. When compared with pure diffusion within vitreous, the ratio of the amount of a model compound, fluorescein, reaching the retina to that cleared by aqueous outflow increased by 93% and 84% for intravitreal injection and implant, respectively, with maximum vitreous outflow (glaucomatous eye). The result shows that the combined “convective” effect due to the vitreous outflow and “wash out” effect by aqueous outflow has significant impact on drug distribution for both intravitreal injection and implant. These two effects should be considered in the design of drug delivery strategies.Copyright © 2004 by ASME

Keratoconus (KC) is progressive disease of corneal thinning, steepening and collagen degradation. Biomechanics of the cornea is maintained by the intricate collagen network, which is responsible for its unique shape and function. With the disruption of this collagen network, the cornea loses its shape and function, resulting in progressive visual degradation. While KC is essentially a stromal disease, there is evidence that the epithelium undergoes significant thinning similar to the stroma. Several topographical approaches have been developed to detect KC early. However, it is now hypothesized that biomechanical destabilization of the cornea may precede topographic evidence of KC. Biomechanics of KC has been investigated only to a limited extent due to lack of in vivo measurement techniques and/or devices. In this review, we focus on recent work performed to characterize the biomechanical characteristics of KC.

The material properties of the cornea are important determinants of corneal shape and refractive power. Corneal ectatic diseases, such as keratoconus, are characterized by material property abnormalities, are associated with progressive thinning and distortion of the cornea, and represent a leading indication for corneal transplantation. We describe a corneal elastography technique based on optical coherence tomography (OCT) imaging, in which displacement of intracorneal optical features is tracked with a 2-D cross-correlation algorithm as a step toward nondestructive estimation of local and directional corneal material properties. Phantom experiments are performed to measure the effects of image noise and out-of-plane displacement on effectiveness of displacement tracking and demonstrated accuracy within the tolerance of a micromechanical translation stage. Tissue experiments demonstrate the ability to produce 2-D maps of heterogeneous intracorneal displacement with OCT. The ability of a nondestructive optical method to assess tissue under in situ mechanical conditions with physiologic-range stress levels provides a framework for in vivo quantification of 3-D corneal elastic and viscoelastic resistance, including analogs of shear deformation and Poisson’s ratio that may be relevant in the early diagnosis of corneal ectatic disease.

In most cases of Pediatric practice, medicine is prescribed to the child without taking into consideration his likes and dislikes. The medicines are usually thrust upon them. Though our foremost aim is to cure the patient, we should give due importance to make the process of cure as comfortable as possible. Keeping this in mind, opinion poll of around nine hundred school students from rural and urban population of age ranging from 11 years to 16 years was taken. The result is analysed and suggestion is given to rationalise the treatment for better compliance.

Purpose To evaluate the biomechanical effect of intraocular pressure (IOP) elevation on the optic nerve/lamina cribrosa complex (ON/LC) and peripapillary sclera (PS) of porcine eyes before and after localized collagen cross-linking. Methods Eighteen porcine globes were divided evenly into three groups. The optic nerves were transected to expose the ON/LC, and each globe was infused through an in-line pressure transducer for direct IOP control. Surface wave velocity, a nondestructive measure of tissue stiffness, was measured across the ON/LC and PS before and after collagen cross-linking at IOPs of 10 and 30 mm Hg (groups 1 and 2) and at each globe's preinflation IOP and 80 mm Hg (group 3). In group 3, papillary strain was measured by analyzing the displacement of fiducial marks immediately adjacent to the ON/LC by using digital photography. Cross-linking in group 1 was achieved with riboflavin-ultraviolet A (UVA) delivery to the entire ON/LC and PS and, in groups 2 and 3, with an annular sponge soaked in glutaraldehyde (GTA) and applied only to the PS. Results Native PS was significantly stiffer than the ON/LC across all experiments. Before cross-linking, IOP elevation caused significant stiffening of both the ON/LC and PS. After cross-linking with either technique, IOP elevation stiffened the PS but not the ON/LC region. In group 3, papillary strain during IOP elevation was significantly reduced after PS cross-linking. Conclusions Stiffening of the peripapillary scleral ring reduces the biomechanical sensitivity of the ON/LC complex to IOP elevation and may represent a novel mechanism for neuroprotection in glaucoma.

Most of the commonly used antitubercular drugs are reported to be safe during pregnancy. There is very little risk of teratogenecity against isoniazid, rifampicin and ethambuto!. Streptomycin is known to cause VIII nerve and vestibular damage in the growing embryo. A case of ophthalmic foetal abnormality while the mother Was on ethambutol, rifampicin and isoniazid therapy during the first trimester of pregnancy is reported here.