Tear meniscus height agreement and reproducibility between two corneal topographers and spectral-domain optical coherence tomography.

CLINICAL RELEVANCE: Tear meniscus height (TMH) is an important clinical marker in dry eye diagnosis and management. PURPOSE: To evaluate the reproducibility and agreement of TMH measurements in non-clinical participants using the Oculus Keratograph 5 M, Medmont Meridia, and Spectral-domain optical coherence tomography (Spectralis SD-OCT). METHODS: Fifty-six participants (mean 43.8 ± 22.4 years) were recruited for this cross-sectional study. Image acquisitions were performed on the three devices, sequentially and randomized. The repeatability and reproducibility of inter-observer and inter-device analysis were performed. Repeated measures ANOVA and Bland-Altman Plots were used to evaluate the agreement between devices. RESULTS: The mean TMH with the Oculus Keratograph 5 M, Medmont Meridia and Spectralis SD-OCT were 0.29 ± 0.16 mm, 0.24 ± 0.09 mm and 0.27 ± 0.16 mm, respectively. There were no significant inter-observer differences (paired t-tests, p < 0.001). All the devices exhibited good inter-observer reliability (ICC ≥ 0.877), and good repeatability (CV ≤ 16.53%). Inter-device reliability is moderate (ICC = 0.621, p < 0.001). Repeated measures ANOVA revealed that TMH measurements given by the Spectralis SD-OCT are not significantly different from the Oculus Keratograph 5 M (p = 0.19) and the Medmont Meridia (p = 0.38). TMH measurements from Oculus Keratograph 5 M were significantly higher than those from Medmont Meridia (p = 0.02). Correlations between the mean TMH and the difference in the TMH measurements were positive for Oculus Keratograph 5 M and Medmont Meridia (r2 = 0.62, p < 0.001), negative for Medmont Meridia and Spectralis SD-OCT (r2 = -0.59, p < 0.001), and not significant for Oculus Keratograph 5 M and Spectralis SD-OCT (r2 = 0.05, p = 0.74). A strong correlation was found for TMH measured with all devices (r2 = 0.55 to 0.81, p < 0.001). CONCLUSIONS: The Oculus Keratograph 5 M, Medmont Meridia, and Spectralis SD-OCT provide reliable and reproducible inter-observer TMH measurements. Inter-device reliability is moderate, with a close correlation between Spectralis SD-OCT and the Oculus Keratograph 5 M. Oculus Keratograph 5 M and Medmont Meridia are repeatable devices appropriate for the measurement of TMH, but they are not interchangeable in clinical practice.

Comparison of different measuring methods in the assessment of the ISNT rule and its variants in a normal population: A cross-sectional study.

PURPOSE: The aim of this study was to compare five different neuroretinal rim (NRR) measurement methods, based on quadrants and NRR widths, in the assessment of the ISNT (inferior (I) > superior (S) > nasal (N) > temporal (T)) rule, and its variants IST (inferior (I) > superior (S) > temporal (S)) rule, IS (inferior (I) > superior (S)) rule and T (temporal is the thinnest) rule in a normal population. Factors influencing compliance with this rule and its variants were also evaluated. METHODS: Stereoscopic fundus images were analysed through a dichoptic viewing system. Two graders labelled the optic disc and cup, as well as the fovea. Custom-made software automatically determined the limits of the optic disc and cup and examined the ISNT rule and its variants using several NRR measurement methods. RESULTS: Sixty-nine subjects with normal eyes were enrolled. For the various NRR measuring methods, the percentage of eyes following the rules, that is, validity ranges were 0.0%-15.9% for the ISNT rule, 31.9%-59.4% for the IST rule, 46.4%-59.4% for the IS rule and 50.7%-100.0% for the T rule. Significant intra-measurement agreement ranges were IST (κ = 0.50-0.85), IS (κ = 0.68-1.00) and T (κ = 0.24-0.77). Only the IST and IS rules achieved significant inter-measurement agreement (κ = 0.47-1.00). After multivariate and receiver operating characteristic (ROC) curve analyses, the vertical cup position cupy (area under the ROC curve (AUROC) = 0.60-0.96; cut-off = |0.005|) was the most important predictor for virtually all NRR measurement agreements for the ISNT, IST and IS rules. The horizontal cup position (AUROC = 0.50-0.92; cut-off = -0.028 to 0.05) was the most important predictive factor for the majority of the NRR measurement agreements for the T rule. CONCLUSIONS: Only the IST and IS rules are valid for the same normal subjects. The most important factor affecting the validity of the ISNT rule and its variants was the anatomical cup position. NRR measurement agreements based on NRR quadrants exhibited larger validity and better agreement. The IST and IS rules can be combined with the alternative SIT (superior (S) > inferior (I) > temporal (T)) and SI (superior (S) > inferior (I)) rules to detect almost all normal subjects.

Optic Disc Localization in Retinal Images Based on Cumulative Sum Fields.

This paper describes an automatic method for the optic disc localization in retinal images, which is effective and reliable with multiple datasets. Particularly, the described method reveals very effective dealing with retinal images with large pathological signs. The algorithm begins with a new vessel enhancement method based on a modified corner detector. Subsequently, a weighted version of the vessel enhancement is combined with morphological operators, to detect the four main vessels orientations {0(°), 45(°), 90(°), 135(°) }. These four image functions have all the necessary information to determine an initial optic disc localization, resulting in two images that are respectively divided along the vertical or horizontal orientations with different division sizes. Each division is averaged creating a 2-D step function, and a cumulative sum of the different sizes step functions is calculated in the vertical and horizontal orientations, resulting in an initial optic disc position. The final optic disc localization is determined by a vessel convergence algorithm using its two most relevant features; high vasculature convergence and high intensity values. The proposed method was evaluated in eight publicly available datasets, including the STARE and DRIVE datasets. The optic disc was localized correctly in 1752 out of the 1767 retinal images (99.15%) with an average computation time of 18.34 s.

Prevalência de anticorpos anti-HIV-I em pacientes em tratamento com hemodiálise / Prevalence of ant-HIV-I antibodies in patients on hemodialysis treatment

Os autores avaliaram, em dois estudos transversais prospectivos, a prevalência de anticorpos antiHIV-I, em pacientes com insuficiência renal crônica em tratamento com hemodiálise. Em 1985, foram estudados 134 pacientes, hemodialisados pelo tempo médio de 20,8 ñ 19,5 meses, e em 1989, 148 pacientes, tratados pelo período de 26,0 ñ 22,8 meses. A prevalência de anticorpos anti-HIV-I foi de 0,74% em 1985 e de 0,67% em 1989. A incidência de anticorpos anti-HIV-I, determinada em 58% dos pacientes inicialmente estudados em 1985, e acompanhados por quatro anos, foi de 0%. Estes resultados, somados aos publicados na literatura, confirmam a irrelevância do problema da SIDA em unidades de hemodiálise e enfatizam a importância da rigorosa triagem do sangue e seus derivados na prevençäo da transmissäo do HIV-I para pacientes sob tratamento hemodialítico