Lara Borrego-Sanz

Agreement between Central Corneal Thickness Measured Using Pentacam, Ultrasound Pachymetry, Specular Microscopy and Optic Biometer Lenstar LS 900 and the Influence of Intraocular Pressure

Purpose: To compare central corneal thickness (CCT) values obtained by Lenstar (LE), Pentacam (PC), specular microscopy (SM) and ultrasound pachymetry (UP) in healthy corneas and study their influence on intraocular pressure (IOP) readings determined by Goldmann applanation tonometry (GAT). Methods: CCT was measured in 76 healthy subjects by LE, PC, SM and UP. We established Lins concordance correlation coefficient (ρ-C) between different techniques. The influence of CCT on GAT was established through univariate linear regression models, IOP being the dependent variable. Results: The highest ρ-C was found between LE and SM at 0.94 (95% CI: 0.91-0.96) and between LE and UP at 0.95 (95% CI: 0.94-0.97). IOP readings showed less variability when CCT was determined using LE (7.7%, B = 0.16; 95% CI: 0.004-0.28). Conclusions: Although CCT values obtained with UP, PC, SM and LE show good correlation, these methods are not completely interchangeable. The amount of IOP variation differs when CCT is determined using LE or SM.

Comparing Corneal Variables in Healthy Subjects and Patients with Primary Open-Angle Glaucoma

PURPOSE This study was designed to identify possible differences between healthy subjects and patients with primary open-angle glaucoma (POAG) in keratometry, central corneal thickness, overall corneal thickness, mean thickness of a circular zone centered at the corneal apex of 1-mm radius (zone I), and mean thickness of several concentric rings also centered at the apex of 1-mm width (zones II to VI, respectively). METHODS These variables were recorded in 126 healthy subjects and 130 patients with POAG. Corneal thicknesses and the power of the flattest and steepest axes were compared between the two populations using a t-test and the position of the flattest axis using a Mann-Whitney U test. A binary logistic regression procedure was used to determine the diagnostic capacity of the corneal variables using the area under the receiver operator characteristic curve (AUC) to select the best regression equation. RESULTS Significant differences between subjects and patients were detected in mean corneal thickness and in mean thicknesses of zones I to VI. The logistic regression model included as predictors the mean corneal thickness and the mean thicknesses of zones IV and VI; for this model, the AUC was 0.711, sensitivity was 67.7%, and specificity was 65.5%. CONCLUSIONS Healthy subjects and glaucoma patients differ significantly in terms of mean overall corneal thickness and thicknesses of the corneal zones I to VI defined here. The variables mean corneal thickness and mean thicknesses of zones IV and VI are able to discriminate between subjects with or without glaucoma.

Correlations between corneal and optic nerve head variables in healthy subjects and patients with primary open angle glaucoma.

AIM To correlate corneal variables (determined using the Pentacam) with optic nerve head (ONH) variables determined using the Heidelberg retina tomograph (HRT) in healthy subjects and patients diagnosed with primary open angle glaucoma (POAG). METHODS Measurements were made in 75 healthy eyes and 73 eyes with POAG and correlations examined through Pearson correlation coefficients between the two sets of variables in the two subject groups. The corneal variables determined were corneal volume (CVol), central corneal thickness (CCT), overall corneal thickness (OvCT), the mean thickness of a circular zone centered at the corneal apex of 1 mm radius (zone I) and the mean thickness of several concentric rings, also centered at the apex until the limbus, each of 1 mm width (zones II to VI respectively). The ONH variables were determined using the HRT. RESULTS The following pairs of variables were correlated in the control group: CCT-disc area (DAr) (-0.48; P<0.0001), Zone I-DAr (-0.503; P<0.0001) and Zone II-DAr (-0.443; P<0.0001); and in the POAG group: CCT-cup-to-disc area ratio (CDRa) (-0.402; P<0.0001), Zone I-CDRa (-0.418; P<0.0001), Zone II-CDRa (-0.405; P=0.006), Zone I-cup shape measure (CSM) (-0.415; P=0.002), Zone II-CSM (-0.405; P=0.001), Zone IV-height variation contour (HVC) (0.378; P=0.002); Zone V-HVC (0.388, P<0.0001). CONCLUSIONS In the healthy subjects, significant negative correlation was detected between central and paracentral corneal thickness and optic disc area. In contrast, the POAG patients showed significant negative correlation between central and paracentral corneal thickness and the cup-disc ratio and CSM, and positive correlation between peripheral corneal thickness and HVC.

Anatomical characterization of central, apical and minimal corneal thickness.

AIM To anatomically locate the points of minimum corneal thickness and central corneal thickness (pupil center) in relation to the corneal apex. METHODS Observational, cross-sectional study, 299 healthy volunteers. Thickness at the corneal apex (AT), minimum corneal thickness (MT) and corneal thickness at the pupil center (PT) were determined using the pentacam. Distances from the corneal apex to MT (MD) and PT (PD) were calculated and their quadrant position (taking the corneal apex as the reference) determined: point of minimum thickness (MC) and point of central thickness (PC) depending on the quadrant position. Two multivariate linear regression models were constructed to examine the influence of age, gender, power of the flattest and steepest corneal axes, position of the flattest axis, corneal volume (determined using the Pentacam) and PT on MD and PD. The effects of these variables on MC and PC were also determined in two multinomial regression models. RESULTS MT was located at a mean distance of 0.909 mm from the apex (79.4% in the inferior-temporal quadrant). PT was located at a mean distance of 0.156 mm from the apex. The linear regression model for MD indicated it was significantly influenced by corneal volume (B=-0.024; 95%CI: -0.043 to -0.004). No significant relations were identified in the linear regression model for PD or the multinomial logistic regressions for MC and PC. CONCLUSION MT was typically located at the inferior-temporal quadrant of the cornea and its distance to the corneal apex tended to decrease with the increment of corneal volume.

Effect of corneal morphometry on dynamic contour and Goldmann applanation tonometry.

Objectives:To determine the effects on dynamic contour tonometry (DCT) and Goldmann applanation tonometry (GAT) of the power of the flattest and steepest corneal meridians, their orientation, central corneal thickness (CCT), mean overall corneal thickness, and the mean thickness of a circular zone centered at the corneal apex of 1 mm radius (zone I) and the mean thicknesses of several concentric rings also centered at the apex of width 1 mm (zones II to VI, respectively). Methods:A total of 136 consecutive healthy eyes were examined. Two multivariate linear regression models were constructed, 1 for each tonometry system. In both models, the predictive variables were: keratometric power of the flattest and steepest axes, flattest axis (as one of the categories 0 to 30, 30 to 60, 60 to 90, 90 to 120, 120 to 150, and 150 to 180 degrees), CCT, mean overall corneal thickness (determined using the Pentacam), and mean thicknesses of corneal zones I, II, III, IV, V, and VI (determined using the Pentacam). Results:The multivariate regression analysis (adjusted R2=0.11; P=0.04) revealed that GAT was influenced by CCT [B=0.042; 95% confidence interval (CI), 0.002-0.085] and the mean thicknesses of zones I (B=0.996; 95% CI, 0.105-1.729), II (B=−1.688; 95% CI, −3.171 to −0.204), and III (B=0.718; 95% CI, 0.028-1.407), whereas DCT was solely affected by the mean thickness of zone II (B=−0.372; 95% CI, −0.728 to −0.016) (adjusted R2=0.13; P=0.02). Conclusions:Although DCT is only affected by the mean thickness of zone II, GAT is influenced by CCT and the mean thickness of zones I, II, and III.

Interferon-associated retinopathy in a patient with metastatic melanoma

We present the unusual case of a 35 year-old woman with stage IV melanoma and widespread metastases, who was undergoing treatment with interferon alpha-2b and who presented with interferon-associated retinopathy. The patient, who had been taking interferon treatment for three months, complained of a sudden loss of visual acuity in the left eye. An ocular examination revealed multiple cotton wool spots along the retina and macular involvement. Interferon treatment was suspended. Although rare, retinopathy represents a potentially serious adverse effect of interferon treatment. Although normally patients are asymptomatic, complications derived of its use may arise, which can lead to significant visual impairment. We therefore suggest that before initiating treatment with this drug, patients should be informed of its potential ocular risks, and that regular eye examinations are conducted along with the treatment.

Characterization of the thickness of different corneal zones in glaucoma: effect on dynamic contour, Goldmann and rebound tonometries

Purpose:  To characterize five models of corneal thickness circular zoning in a sample of healthy controls and a sample of patients with primary open‐angle glaucoma (POAG) and to determine their effect on Goldmann (GAT), dynamic contour (DCT) and rebound tonometers (RT).

Disease Remission in Children and Adolescents with Intermediate Uveitis: A Survival Analysis

Purpose: To report the incidence rate (IR) of remission in pediatric noninfectious intermediate uveitis (IU). Methods: Longitudinal retrospective cohort study, including 19 patients (32 eyes) between 1985 and 2014, followed-up until loss or January 2016. Remission was defined following the Standardization of Uveitis Nomenclature workshop criteria, prolonged remission as a remission spanning 12 months and until the end of follow-up, and relapse as recurrence of inflammatory activity in an eye in remission. Results: Median follow-up time was 6.3 years. IRs (95% confidence interval) for remission, relapse, and prolonged remission were 18.6 (13.1–26.5), 32.3 (20.6–50.7), and 6.7 (3.8–11.9) episodes per 100 eye-years, respectively. 48% of eyes relapsed in the first year following remission. 25 and 50% of eyes achieved prolonged remission after 5 and 10 years of follow-up, respectively. Conclusions: Inflammatory relapses may be frequent in noninfectious IU affecting children and adolescents, appearing early after remission. Also, prolonged remission seems infrequent, being achieved late during follow-up.

Comparison of corneal biomechanical properties of patients with dry eye secondary to Sjögren's syndrome and healthy subjects

PURPOSE The goal of this study is to determine whether any difference in corneal biomechanical properties exists between Sjögrens syndrome dry eye patients and healthy subjects. METHODS Thirty-one patients diagnosed with Sjögrens syndrome and associated dry eye manifestations and 44 healthy individuals were included in the study. Ultrasonic pachymetry (UP) was used to measure central corneal thickness (CCT). Corneal biomechanical parameters were obtained using ocular response analyzer (ORA). The main parameters assessed were corneal hysteresis (CH), corneal resistance factor (CRF), Goldmann correlated intraocular pressure (IOPg) and corneal compensated IOP (IOPcc). A Students t-test for independent groups was performed to compare the mean of these variables between both groups. RESULTS Mean CH values in Sjögrens syndrome and healthy subject eyes were 10.1mmHg and 11.18mmHg respectively, representing a statistically significant difference (P=0.003). No other variable measured differed between cases and controls (P>0.05). Mean CRF values were 9.51mmHg and 10.37mmHg respectively, and mean CCT measured by UP in cases and controls was 527.41μm and 552.51μm respectively. CONCLUSIONS Sjögrens syndrome can influence corneal biomechanical properties, specifically CH. ORA measurements should be considered of interest in the evaluation of Sjögren syndrome subjects.