Characteristics of Astigmatism after MyoRing Implantation

Considering the rising number of MyoRing implantation procedures in keratoconic corneas and the refractive outcomes associated with this treatment modality, this study aimed to evaluate and compare the magnitude and axis orientation of total and corneal astigmatism between before and after MyoRing implantation in 34 eyes of 28 patients with keratoconus (KCN) (mean age: 29.41 ± 7.0 years). The inclusion criterion was a reliable diagnosis of clinical KCN based on corneal biomicroscopic and tomographic findings. The mean total astigmatism of ocular refraction decreased significantly from -4.27 ± 3.15 D (before MyoRing implantation) to -2.18 ± 1.63 D (after MyoRing implantation) (P < 0.001). The mean astigmatism in the anterior and posterior surface of the cornea decreased significantly by 1.16 D (P = 0.001) and 0.24 D (P = 0.009), respectively, after MyoRing implantation. Before MyoRing implantation, the axis orientation of total ocular astigmatism for with-the-rule, oblique, and against-the-rule astigmatism was 21%, 42%, and 37%, respectively; at 6 months after MyoRing implantation, it was 18%, 24%, and 58%, respectively. Before MyoRing implantation, the axis orientation for with-the-rule, against-the-rule, and oblique astigmatism of the anterior surface of the cornea was 59%, 24%, and 17%, respectively; at 6 months after MyoRing implantation, it was 52%, 24%, and 24%, respectively. Before MyoRing implantation, the axis orientation of with-the-rule, oblique, and against-the-rule astigmatism of the posterior surface of the cornea was 68%, 29%, and 3%, respectively; at 6 months after MyoRing implantation, it was 67%, 12%, and 12%, respectively. MyoRing implantation significantly decreased the amount of total, anterior, and posterior corneal astigmatism

A Contralateral Eye Study Comparing Corneal Biomechanics in Subjects with Bilateral Keratoconus with Unilateral Vogt’s Striae

The aim of this study was to analyze and compare corneal biomechanics in patients with bilateral keratoconus (KCN) with unilateral Vogt’s striae. In this prospective contralateral study, visual acuity, refraction, and corneal biomechanical parameters were evaluated in patients with bilateral KCN with unilateral Vogt’s striae using the Ocular Response Analyzer (ORA) (Reichert Inc., Buffalo, NY) and Corvis ST (Oculus Optikgeräte GmbH, Wetzlar, Germany). All patients underwent a comprehensive ophthalmic examination, including uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), refraction (calculated by vectorial analysis), slit-lamp biomicroscopy, and Scheimpflug-based tomography. The patients enrolled in this study had a reliable diagnosis of bilateral clinical KCN with unilateral Vogt’s striae based on slit-lamp signs as well as corneal topographic/tomographic maps.  Fifty patients aged 18 to 40 years were included in this study. There was a significant difference in all clinical (distance visual acuity and refraction) and corneal biomechanical parameters between KCN eyes with and without unilateral Vogt’s striae (all P < 0.05). However, there were no significant differences in peak distance (P = 0.291), corneal compensated intraocular pressure (IOPCC) (P = 0.08), and J45 (P = 0.131) between the two groups. Most corneal biomechanical parameters, except for peak distance, IOPCC, and J45, showed a significant difference between KCN eyes with and without unilateral Vogt’s striae. Vogt’s striae may cause corneal biomechanical deterioration. This information could be used in clinical practice.Â

The Relationship of Body Mass Index and Blood Pressure with Corneal Biomechanical Parameters in Healthy Subjects

This study aimed to assess the possible relationship of body mass index (BMI) and blood pressure (BP) with corneal biomechanical parameters in healthy subjects. The study included 88 eyes of 88 healthy subjects aged 20–40 years. After a thorough medical history, a digital sphygmomanometer was used to measure the systolic blood pressure (SBP) and diastolic blood pressure (DBP). In addition, several hematological and biochemical parameters were determined to assess general health. Before the ophthalmic examination, the body height and weight were measured; then, the BMI was calculated. Finally, after comprehensive ophthalmic examination, all cases were evaluated with Pentacam (Oculus) in order to rule out corneal ectasia; then, the corneal biomechanical parameters of all individuals were measured using the Scheimpflug-based Corvis ST (Oculus Optikgeräte GmbH, Wetzlar, Germany). If the measurements of the hematological and biochemical parameters were within normal range, the results of the Corvis ST, BMI, and BP were included in the analysis carried out with SPSS software. The mean (± standard deviation [SD]) BMI, SBP, DBP, intraocular pressure (IOP), central corneal thickness (CCT), deformation amplitude, radius, and peak distance was 27.24 ± 4.80 kg/m2, 116.47 ± 11.21 mmHg, 80.51 ± 5.68 mmHg, 15.10 ± 1.70 mmHg, 533.10 ± 30.97 ï­m, 1.03 ± 0.11 mm, 7.51 ± 0.86 mm, and 5.03 ± 0.30 mm, respectively. According to the World Health Organization’s classification of BMI, the results showed no significant difference in IOP, CCT, peak distance, radius, and deformation amplitude between different BMI subcategories (all P > 0.05). The results of the Corvis ST showed that corneal biomechanical parameters had no significant correlation with BMI, SBP, and DBP in three subgroups of BMI and all participants (all P > 0.05) but the results showed a positive correlation between CCT and IOP (P < 0.001, r = 0.504) in all participants. CCT and IOP had no correlation with BMI, SBP, and DBP (all P > 0.05). This study showed that BMI and BP had no correlation with corneal biomechanical parameters in healthy subjects using the Corvis ST. Our results can be used in clinical practice.Â

A Contralateral Eye Study Comparing Corneal Biomechanics in Subjects with Bilateral Keratoconus with Unilateral Vogt’s Striae

The aim of this study was to analyze and compare corneal biomechanics in patients with bilateral keratoconus (KCN) with unilateral Vogt’s striae. In this prospective contralateral study, visual acuity, refraction, and corneal biomechanical parameters were evaluated in patients with bilateral KCN with unilateral Vogt’s striae using the Ocular Response Analyzer (ORA) (Reichert Inc., Buffalo, NY) and Corvis ST (Oculus Optikgeräte GmbH, Wetzlar, Germany). All patients underwent a comprehensive ophthalmic examination, including uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), refraction (calculated by vectorial analysis), slit-lamp biomicroscopy, and Scheimpflug-based tomography. The patients enrolled in this study had a reliable diagnosis of bilateral clinical KCN with unilateral Vogt’s striae based on slit-lamp signs as well as corneal topographic/tomographic maps.  Fifty patients aged 18 to 40 years were included in this study. There was a significant difference in all clinical (distance visual acuity and refraction) and corneal biomechanical parameters between KCN eyes with and without unilateral Vogt’s striae (all P < 0.05). However, there were no significant differences in peak distance (P = 0.291), corneal compensated intraocular pressure (IOPCC) (P = 0.08), and J45 (P = 0.131) between the two groups. Most corneal biomechanical parameters, except for peak distance, IOPCC, and J45, showed a significant difference between KCN eyes with and without unilateral Vogt’s striae. Vogt’s striae may cause corneal biomechanical deterioration. This information could be used in clinical practice.

Corneal topography and higher-order aberrations in patients with type 2 diabetes mellitus

Background: Changes in blood sugar levels cause alterations in the anterior segment and retina of the eye. This study was aimed at evaluating corneal topography, aberrometry, and corneal asphericity in patients with treatment-naive type 2 diabetes mellitus (T2DM). Methods: Participants with treatment-naive T2DM were enrolled in this cross-sectional study. The inclusion criteria were glycated hemoglobin A1c (Hb A1c) greater than or equal to 7.5% and absence of other ocular or systemic diseases. Patients who refused to participate or had a history of topical or systemic steroid use, hyperlipidemia, hypertension, anemia, prior ocular disorder or surgery, diabetic retinopathy, glaucoma, cataract, active ocular inflammatory or infectious disease, or contact lens use were excluded. All participants underwent a comprehensive ophthalmic examination. The Pentacam HR Scheimpflug tomography system (Pentacam High Resolution; Oculus, Wetzlar, Germany) was used to measure the anterior-segment parameters. Results: Sixty eyes of 30 patients with a male-to-female ratio of 1:1 were included; the mean (standard deviation [SD]) age and Hb A1c were 51.63 (6.73) years and 8.82% (1.31%), respectively. The mean (SD) values of central corneal thickness, root mean square (RMS) of total aberration, RMS of lower-order aberrations, RMS of higher-order aberrations, spherical aberration, 0° coma, 90° coma, flat anterior keratometry (K), steep anterior K, mean anterior K, anterior topographic astigmatism, flat posterior K, steep posterior K, mean posterior K, posterior topographic astigmatism, anterior corneal asphericity, and posterior corneal asphericity were 540.22 (24.47) µm, 1.72 (0.73) µm, 1.63 (0.73) µm, 0.51 (0.17) µm, + 0.31 (0.09) µm, - 0.06 (0.15) diopters (D), 0.003 (0.21) D, 43.87 (1.49) D, 44.69 (1.50) D, 44.28 (1.44) D, + 0.82 (0.83) D, - 6.25 (0.27) D, - 6.55 (0.31) D, - 6.40 (0.28) D, - 0.30 (0.15) D, - 0.32 (0.12) Q-value, and - 0.47 (0.17) Q-value, respectively. Conclusions: We presented the mean values of Pentacam parameters for aberrometry, keratometry, and corneal asphericity in patients with treatment-naive T2DM. These values could serve as a baseline for prospective monitoring of the ocular health status of this cohort and for comparison with future cohorts of patients with well-controlled T2DM. Further studies are required to assess the presence and applicability of ocular changes following intensive blood glucose control in T2DM and further understand the related pathophysiology

The Relationship of Body Mass Index and Blood Pressure with Corneal Biomechanical Parameters in Healthy Subjects

This study aimed to assess the possible relationship of body mass index (BMI) and blood pressure (BP) with corneal biomechanical parameters in healthy subjects. The study included 88 eyes of 88 healthy subjects aged 20–40 years. After a thorough medical history, a digital sphygmomanometer was used to measure the systolic blood pressure (SBP) and diastolic blood pressure (DBP). In addition, several hematological and biochemical parameters were determined to assess general health. Before the ophthalmic examination, the body height and weight were measured; then, the BMI was calculated. Finally, after comprehensive ophthalmic examination, all cases were evaluated with Pentacam (Oculus) in order to rule out corneal ectasia; then, the corneal biomechanical parameters of all individuals were measured using the Scheimpflug-based Corvis ST (Oculus Optikgeräte GmbH, Wetzlar, Germany). If the measurements of the hematological and biochemical parameters were within normal range, the results of the Corvis ST, BMI, and BP were included in the analysis carried out with SPSS software. The mean (± standard deviation [SD]) BMI, SBP, DBP, intraocular pressure (IOP), central corneal thickness (CCT), deformation amplitude, radius, and peak distance was 27.24 ± 4.80 kg/m2, 116.47 ± 11.21 mmHg, 80.51 ± 5.68 mmHg, 15.10 ± 1.70 mmHg, 533.10 ± 30.97 m, 1.03 ± 0.11 mm, 7.51 ± 0.86 mm, and 5.03 ± 0.30 mm, respectively. According to the World Health Organization’s classification of BMI, the results showed no significant difference in IOP, CCT, peak distance, radius, and deformation amplitude between different BMI subcategories (all P > 0.05). The results of the Corvis ST showed that corneal biomechanical parameters had no significant correlation with BMI, SBP, and DBP in three subgroups of BMI and all participants (all P > 0.05) but the results showed a positive correlation between CCT and IOP (P < 0.001, r = 0.504) in all participants. CCT and IOP had no correlation with BMI, SBP, and DBP (all P > 0.05). This study showed that BMI and BP had no correlation with corneal biomechanical parameters in healthy subjects using the Corvis ST. Our results can be used in clinical practice.

Regionalization by fuzzy expert system based approach optimized by genetic algorithm.

In recent years soft computing methods are being increasingly used to model complex hydrologic processes. These methods can simulate the real life processes without prior knowledge of the exact relationship between their components. The principal aim of this paper is perform hydrological regionalization based on soft computing concepts in the southern strip of the Caspian Sea basin, north of Iran. The basin with an area of 42,400 sq. km has been affected by severe floods in recent years that caused damages to human life and properties. Although some 61 hydrometric stations and 31 weather stations with 44 years of observed data (1961–2005) are operated in the study area, previous flood studies in this region have been hampered by insufficient and/or reliable observed rainfall-runoff records. In order to investigate the homogeneity (h) of catchments and overcome incompatibility that may occur on boundaries of cluster groups, a fuzzy expert system (FES) approach is used which incorporates physical and climatic characteristics, as well as flood seasonality and geographic location. Genetic algorithm (GA) was employed to adjust parameters of FES and optimize the system. In order to achieve the objective, a MATLAB programming code was developed which considers the heterogeneity criteria of less than 1 (H < 1) as the satisfying criteria. The adopted approach was found superior to the conventional hydrologic regionalization methods in the region because it employs greater number of homogeneity parameters and produces lower values of heterogeneity criteria

A contralateral eye study comparing characteristics of corneal endothelial cells in bilateral keratoconus patients with unilateral corneal Vogt's striae

Purpose: The aim of this study was to analyze and compare corneal endothelial cell morphology and characteristics in bilateral keratoconus (KCN) patients with unilateral Vogt's striae. Methods: Fifty patients aged 20–38 years were recruited in this cross-sectional contralateral eye study. In this study, corneal endothelial cell parameters were evaluated in patients with bilateral KCN and unilateral Vogt's striae using the Topcon SP2000P specular microscope (Topcon, Tokyo, Japan). Results: In the current study, there were no significant differences in corneal endothelial cell parameters including endothelial cell density (ECD), hexagonal cell ratio (HEX), and coefficient of variance of cell size (CV) between the KCN groups with and without Vogt's striae, [(2968.34 ± 276.65 vs. 2980.05 ± 253.30, P = 0.618), (51.88 ± 13.57 vs. 53.24 ± 9.31, P = 0.658), and (32.50 ± 5.40 vs. 32.97 ± 4.07, P = 0.467), respectively]. Also, among study groups with and without Vogt's striae, ECD did not correlate with anterior chamber depth (ACD) [(P = 0.564, r = 0.09), (P = 0.219, r = −0.18), respectively], maximum keratometry (Kmax) [(P = 0.215, r = 0.18), (P = 0.898, r = 0.02), respectively], and central corneal thickness (CCT) [(P = 0.989, r = −0.02), (P = 0.643, r = −0.07), respectively].Our results showed significant differences in corrected and uncorrected distance visual acuity (UDVA), cycloplegic refractive error components (calculated by vectorial analysis), CCT, and Kmax between two study groups (all P < 0.05) except for J45 (Jackson cross cylinder, axes at 45 and 135°) (P = 0.131). Conclusions: We were not able to find the statistically significant differences in ECD, HEX, and CV between KCN eyes with and without Vogt's striae. Despite clinical and tomographic results, it seems that Vogt's striae cannot cause deterioration in the corneal endothelial morphology. Keywords: Keratoconus, Corneal endothelial cell, Vogt's striae, Endothelial cell density, Contralateral eye stud

Refractive Error and Ocular Biometric Changes in the Treatment of Diabetes Mellitus

Background and Objectives: Evaluation of changes in refractive errors and biometric parameters in the process of glycemic control in people with type 2 diabetes during three-month treatment. Methods: Patients with the first diagnosis of type 2 diabetes or a history of poor glycemic control (hemoglobin glycate more than 7.5%) and without any systemic disease other than diabetes were included. Hemoglobin glycate, refractive error, and biometric parameters were evaluated before treatment and one and a half and three months after treatment, and their changes were examined by generalized estimating equation (GEE) analysis. Results: A total of 60 eyes of 30 patients with a mean age of 51.63±6.79 years were evaluated. Hemoglobin glycate decreased by an average of 1.028% compared to the baseline measurement in the third month (P<0.001). Mean spherical (P=0.554), spherical equivalent (P=0.340), axial length (P=0.147), and anterior chamber depth (P=0.336) did not show a significant difference between the three examinations. In contrast, the lens thickness showed a significant decrease during treatment (P=0.001). Finally, generalized estimating equation (GEE) analysis showed that a 1% decrease in hemoglobin glycate increased by 0.226 mm. (P=0.002) in the axial length. It should be mentioned in tables FU1means Follow-up 1.5 months and FU2 means Follow-up 3 months. Conclusion: The present study shows that refractive errors and most ocular biometric parameters do not change significantly compared to the baseline levels in the period of one and a half and three months after the start of glycemic control

The effect of Ramadan fasting on micronutrients and their relationship with the ocular axial length and anterior chamber depth

Introduction: The present study aimed to assess the effects of Ramadan fasting on micronutrients and their correlations with ocular biometry. Methods: This prospective study was conducted on 89 healthy volunteers (51 males and 38 females) with the mean of 34.98±9.10 years in Mashhad, Iran. Participants received complete ophthalmic and systemic examinations one week before and one week after the holy month of Ramadan in 2015. Subjects with no history of systemic and ophthalmic diseases were enrolled in the study. Blood samples were obtained from all the participants in the morning in both phases of the study. Levels of micronutrients were measured in the blood samples using the Hitachi 717 analyzer (Hitachi, Japan). In addition, IOLMaster (Carl Zeiss Meditec AG, Germany) was applied to determine the ocular axial length (AL) and anterior chamber depth (ACD). Results: No significant differences were observed in the AL and ACD of the subjects before and after Ramadan fasting (P>0.05). Fasting was found to decrease the levels of uric acid, selenium, sodium, and potassium (P0.05). Moreover, no significant association was observed between the AL and ACD with the concentrations of the micronutrients during Ramadan (P>0.05). Conclusion: According to the results, fasting had no significant effects on the overall health and ocular biometry of the fasting individuals during Ramadan. Therefore, it seems that Ramadan fasting is a safe for healthy adults