Sort by
Evaluation of corneal power from an AS-OCT thick lens model and ray tracing: reliability of the keratometer index

Purpose: To investigate and compare different strategies of corneal power calculations using keratometry, paraxial thick lens calculations and ray tracing. Setting: Tertiary care center. Design: Retrospective single-center consecutive case series. Methods: Using a dataset with 9780 eyes of 9780 patients from a cataractous population the corneal front (Ra/Qa) and back (Rp/Qp) surface radius/asphericity, central corneal thickness (CCT), and entrance pupil size (PUP) were recorded using the Casia 2 tomographer. Beside keratometry with the Zeiss (PKZ) and Javal (PKJ) keratometer index, a thick lens paraxial formula (PG) and ray tracing (PR) was implemented to extract corneal power for pupil sizes from 2 mm to 5 mm in steps of 1 mm and PUP. Results: With PUP PKZ/PKJ overestimates the paraxial corneal power PG in around 97%/99% of cases and PR in around 80% to 85%/99%. PR is around 1/6 or 5/6 diopters (D) lower compared with PKZ or PKJ. For a 2 mm pupil PR is around 0.20/0.91 D lower compared with PKZ/PKJ and for a 5 mm pupil PR is comparable with PKZ (around 0.03 D lower) but around 0.70 to 0.75 D lower than PKJ. Conclusions: “True” values of corneal power are mostly required in lens power calculations before cataract surgery, and overestimation of corneal power could induce trend errors in refractive outcome with axial length and lens power if compensated with the effective lens position.

Just Published
Relevant
Evaluation of statistical correction strategies for corneal back surface astigmatism with toric lenses: a vector analysis.

To compare actual and formula-predicted postoperative refractive astigmatism using measured posterior corneal power measurements and 4 different empiric posterior corneal astigmatism correction models. Tertiary care center. Single-center retrospective consecutive case series. Using a dataset of 211 eyes before and after tIOL implantation (Hoya Vivinex), IOLMaster 700 (IOLM) or Casia2 (CASIA) keratometric and front/back surface corneal power measurements were converted to power vector components C0 (0/90 degrees) and C45 (45/135 degrees). Differences between postoperative and Castrop formula predicted refraction at the corneal plane using the labeled parameters of the tIOL and the keratometric or front/back surface corneal powers were recorded as the effect of corneal back surface astigmatism (BSA). Generally, the centroid of the difference shifted toward negative C0 values indicating that BSA adds some against the rule corneal astigmatism (ATR). From IOLM/CASIA keratometry, the average difference in C0 was 0.39/0.32 diopter (D). After correction with the Abulafia-Koch, Goggin, La Hood, and Castrop nomograms, it was -0.18/-0.24 D, 0.27/0.18 D, 0.13/0.08 D, and 0.17/0.10 D. Using corneal front/back surface data from IOLM/CASIA, the difference was 0.18/0.12 D. The Abulafia-Koch method overcorrected the ATR, while the Goggin, La Hood, and Castrop models slightly undercorrected ATR, and using measurements from the CASIA tomographer seemed to produce slightly less prediction error than IOLM.

Just Published
Relevant
Limitations of constant optimization with disclosed intraocular lens power formulae.

To investigate the effect of formula constants on predicted refraction and limitations of constant optimization for classical and modern intraocular lens (IOL) power calculation formulae. Tertiary care center. Retrospective single-center consecutive case series. This analysis is based on a dataset of 888 eyes before and after cataract surgery with IOL implantation (Hoya Vivinex). Spherical equivalent refraction predSEQ was predicted using IOLMaster 700 data, IOL power, and formula constants from IOLCon ( https://iolcon.org ). The formula prediction error (PE) was derived as predSEQ minus achieved spherical equivalent refraction for the SRKT, Hoffer Q, Holladay, Haigis, and Castrop formulae. The gradient of predSEQ (gradSEQ) as a measure for the effect of the constants on refraction was calculated and used for constant optimization. Using initial formula constants, the mean PE was -0.1782 ± 0.4450, -0.1814 ± 0.4159, -0.1702 ± 0.4207, -0.1211 ± 0.3740, and -0.1912 ± 0.3449 diopters (D) for the SRKT, Hoffer Q, Holladay, Haigis, and Castrop formulas, respectively. gradSEQ for all formula constants (except gradSEQ for the Castrop R) decay with axial length because of interaction with the effective lens position (ELP). Constant optimization for a zero mean PE (SD: 0.4410, 0.4307, 0.4272, 0.3742, 0.3436 D) results in a change in the PE trend over axial length in all formulae where the constant acts directly on the ELP. With IOL power calculation formulae where the constant(s) act directly on the ELP, a change in constant(s) always changes the trend of the PE according to gradSEQ. Formulae where at least 1 constant does not act on the ELP have more flexibility to zero the mean or median PE without coupling with a PE trend error over axial length.

Relevant
Accuracy comparison of tomography devices for ray tracing-based intraocular lens calculation.

To evaluate the interchangeability of different tomography devices used for ray tracing-based intraocular lens (IOL) calculation. Eye clinic, Castrop-Rauxel, Germany. Retrospective analysis. Measurements from 3 Placido-Scheimpflug devices and 3 optical coherence tomography (OCT) devices were compared in 83 and 161 other eyes after cataract surgery, respectively. 2-dimensional matrices of anterior local corneal curvature and local corneal thickness are transferred to the ray-tracing software OKULIX. Calculations are performed with the same IOL in the same position of an eye with the same axial length. Differences in spherical equivalent (SE), astigmatism, and spherical aberration are evaluated. Furthermore, the influence of the size of the matrices (optical zone) on the accuracy is quantified. For the Placido-Scheimpflug devices, the deviations from the average of three measurements taken for each eye in SE (mean ± SD) were 0.17 ± 0.24 diopters (D), -0.26 ± 0.29 D, and 0.08 ± 0.39 D ( P < .001, analysis of variance [ANOVA]), for the centroids of the astigmatic differences 0.04 D/173 degrees, 0.14 D/93 degrees, and 0.10 D/7 degrees, and for the median of the absolute values of the vector differences 0.31 D, 0.33 D, and 0.29 D. For OCT devices, the corresponding results were 0.01 ± 0.21 D, -0.03 ± 0.21 D, and 0.02 ± 0.20 D ( P = .005, ANOVA); 0.18 D/120 degrees, 0.07 D/70 degrees, and 0.22 D/4 degrees; and 0.26 D, 0.30 D, and 0.33 D. The accuracy of the calculated spherical aberrations allows for an individual selection of the best fitting IOL model in most cases. The differences are small enough to make the devices interchangeable regarding astigmatism and spherical aberration. Although there are significant differences in SE between Scheimpflug and OCT devices, the differences between OCT devices are also small enough to make them interchangeable, but the differences between Placido-Scheimpflug devices are too large to make these devices interchangeable.

Relevant
The overlap of chronic obstructive pulmonary disease and obstructive sleep apnea in hospitalizations for acute exacerbation of COPD.

This study examined in-hospital outcomes for patients with both chronic obstructive pulmonary disease (COPD) and obstructive sleep apnea (OSA), also known as COPD-OSA overlap syndrome, during hospitalizations for acute exacerbation of COPD (AECOPD). The National Inpatient Sample was used to examine in-hospital mortality, length of stay, costs, and utilization of supportive ventilation in patients with COPD-OSA overlap during AECOPD hospitalizations. A one-to-one matched case-control design was utilized to match patients with and without OSA. Multivariate logistic regression modeling was used to examine mortality and ventilatory support, while controlling for potentially confounding diagnoses. COPD-OSA overlap was associated with longer median length of stay (4 days OSA, 3 days non-OSA; P<0.001), higher mean costs ($32,197 OSA, $29,011 non-OSA; P<0.001), increased utilization of non-invasive positive pressure ventilation (NIPPV) (13.92% OSA, 6.78% non-OSA; P<0.001), and when required for greater than 96 hours, earlier initiation of mechanical ventilation (2.53 days OSA, 3.35 days non-OSA; P=0.001). However, COPD-OSA overlap was associated with reduced mortality (0.81% OSA, 1.05% non-OSA; P<0.001). These differences in mortality (adjusted OR: 0.650; 95% CI 0.624 - 0.678) and NIPPV usage (adjusted OR: 1.998; 95% CI 1.970 - 2.026) remained when adjusted for confounders. Patients with COPD-OSA overlap have higher utilization of supportive ventilation and longer length of stay during AECOPD hospitalizations, contributing to higher costs. The diagnosis of OSA is associated with reduced mortality in these hospitalizations, which may be related to greater utilization of supportive ventilation when OSA is recognized.

Relevant
Trends of Hepatocellular Carcinoma (HCC) Inpatients Mortality and Financial Burden From 2011 to 2017: A Nationwide Analysis.

Liver cancer, including Hepatocellular carcinoma (HCC) is the seventh most common tumor worldwide. Previously, the financial burden of HCC in the United States between 2002 and 2011 was noted to be continuously increasing. This study aims to evaluate temporal trends of hospitalizations due to HCC. This is a retrospective analysis utilizing the National Inpatient Sample (NIS) database. All subjects admitted between 2011 and 2017 with a diagnosis of HCC were identified. The primary trend characteristics were in-hospital mortality, hospital charges, and length of stay. An increase in hospitalization from 67,779 (0.18%) admissions in 2011 to 84,580 (0.23%) admissions in 2017(P<0.05) was noted. Most patients were 45 to 64 years old (median 50%), predominantly men (median 68%) (P<0.05). The primary health care payer was Medicare (Median 49%) and Medicaid (Median 18%) (P<0.05). The most common geographical location was the south (Median 36%) (P<0.05). Most patients were admitted to large hospitals (Median 62%) in urban areas (P<0.05). The median inpatient mortality was estimated to be 9% in 2017 (P<0.05), which has decreased from 10%(P<0.05) in 2011. The total charges per admission have increased steadily from $58,406 in 2011 to $78,791 in 2017 (P<0.05). The median length of stay has increased from 5.79 (SD 6.93) in 2011 to 6.07 (SD 8.3) in 2017(P<0.05). The most common mortality risk factor was sepsis, Acute renal failure, and GI hemorrhage. HCC-related admissions continue to be on the rise. HCC mortality has decreased across the years with earlier diagnoses and advances in therapy. However, we observed a significant increase in financial burden on health care with increasing in-hospital costs, a finding that needs to be verified in prospective trials.

Relevant
Stress and Infant Media Exposure During COVID-19: A Study Among Latino Families.

The COVID-19 pandemic disproportionately harmed Latino families; however, its effects on their stress and media routines remain understudied. We examined economic and parenting stress patterns during the COVID-19 pandemic and estimated associations between these forms of stress and nonadherence to American Academy of Pediatrics (AAP) infant media exposure recommendations among Latino families. We also explored how nonadherence with AAP recommendations varied with COVID-19 cases. We analyzed baseline data from an ongoing clinical trial recruiting low-income Latino parent-infant dyads. Nonadherence with AAP media exposure recommendations (ScreenQ) and economic and parent stress were measured using parent reports. Additional variables included epidemiological data on COVID-19 cases. Linear models examined associations between the pandemic and both stress variables as well as between stress and ScreenQ. Using locally weighted scatterplot smoothing curve fitting, the rise and fall of NJ COVID-19 cases were overlayed with ScreenQ scores over time to visualize and explore trends. All parents identified as Latino (62.6% unemployed, 91.5% limited English proficiency). Mean infant age was 8.2 months. Parent stress increased over time during the COVID-19 pandemic (r = 0.13, p = 0.0369). After covariate adjustment, economic and parent stress were associated with increased nonadherence with AAP recommendations (standardized beta = 0.16, 95% confidence interval [CI], 0.03-0.29; standardized beta = 0.18, 95% CI, 0.04-0.31, respectively). Nonadherence to media exposure recommendations seemed to track with rises in the number of COVID-19 cases with a lag of 7 days. Parent and economic stress were associated with nonadherence to infant media exposure recommendations among Latino families. These findings highlight the need for practitioners to support families from under-resourced communities and to promote healthy media routines.

Relevant