294 research outputs found
Systematic review of the association between Alzheimer’s disease and chronic glaucoma
No full textSarah F Janssen,1 Nomdo M Jansonius,2 Femke Bouwman,3 Frank D Verbraak,1,4 Arthur A Bergen51Department of Ophthalmology, VU Medical Center, Amsterdam; 2Department of Ophthalmology, University of Groningen, University Medical Center Groningen, Groningen; 3Alzheimer Center, VU Medical Center, 4Department of Ophthalmology, 5Department of Clinical Genetics, Academic Medical Center, Amsterdam, the NetherlandsWe read with great interest the paper by Tsilis et al entitled "Systematic review of the association between Alzheimer’s disease and chronic glaucoma" published recently in this journal.1 The potential overlap in the pathobiological background of Alzheimer’s disease (AD) and primary open angle glaucoma (POAG) is currently a topic of intense discussion and could provide further insight into both of these complex diseases.View original paper by Tsilis et al
Progression detection in glaucoma can be made more efficient by using a variable interval between successive visual field tests
No full textThis study aimed to gain insight into the optimal spacing in time for visual field tests for progression detection in glaucoma. Three perimetric strategies for progression detection were compared by means of simulation experiments in a theoretical cohort. In strategies 1 and 2, visual field testing was performed with fixed-spaced inter-test intervals, using intervals of 3 and 6 months respectively. In strategy 3, the inter-test interval was kept at 1 year as long as the fields appeared unchanged. Then, as soon as progression was suspected, confirmation or falsification were performed promptly. Follow-up fields were compared against a baseline assuming linear deterioration, using various progression criteria. Outcome measures were: (1) specificity, (2) time delay until the diagnosis of definite progression, and (3) number of required tests. Strategies 2 and 3 had a higher specificity than strategy 1. Strategies 1 and 3 detected progression earlier than strategy 2. The number of required visual field tests was lowest for strategy 3. Perimetry in glaucoma can be optimised by postponing the next test under apparently stable field conditions and bringing the next test forward once progression is suspected
A relationship between tube length and intraocular pressure after glaucoma drainage implant surgery cannot be explained by Poiseuille's law
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Tool to estimate optical metrics from summary wave-front analysis data in the human eye
No full text<p>Purpose Studies in the field of cataract and refractive surgery often report only summary wave-front analysis data data that are too condensed to allow for a retrospective calculation of metrics relevant to visual perception. The aim of this study was to develop a tool that can be used to estimate these metrics from summary wave-front analysis data. Methods The core of the tool is a two-parameter (primary spherical aberration and an overall measure of all other higher-order aberrations) model for the statistical description of the optical aberrations of the human eye. Modulation transfer through-focus curves were calculated for realistic ranges of spherical aberration, other higher-order aberrations and pupil diameters, for both white and monochromatic light. A series of commonly used metrics (modulation transfer, Strehl ratio, visual Strehl ratio and width of line spread function) was derived from these through-focus curves, with corresponding location of optimal focus and depth-of-focus. Results Published wave-front analysis data from healthy subjects served as input for the tool. The output was compared to published measurements of the included metrics, performed in the same or in comparable samples. Agreement between output of the tool and measurements was within the accuracy of the data. Conclusions The tool is able to relate accurately summary wave-front analysis data from groups of patients to metrics relevant to visual perception and can thus be used to estimate these metrics in situations where their calculation from raw wave-front analysis data is not possible.</p>
Spherical aberration and other higher-order aberrations in the human eye: from summary wave-front analysis data to optical variables relevant to visual perception
No full textWave-front analysis data from the human eye are commonly presented using the aberration coefficient c(4)(0) (primary spherical aberration) together with an overall measure of all higher-order aberrations. If groups of subjects are compared, however, the relevance of an observed difference cannot easily be assessed from these summary aberration measures. A method was developed for estimating various optical variables relevant to visual perception from summary wave-front analysis data. These variables were the myopic shift (the difference in the optimal focus between high and low spatial frequencies, a threat to the simultaneous in-focus viewing of fine and coarse patterns), the depth-of-focus (at 8 cpd), and the modulation transfer at high (16 cpd; reading small print) and low (4 cpd; edge detection) spatial frequencies. The depth-of-focus was defined in two ways: using a relative measure (the full width at half-height of the through-focus curve) and an absolute measure (the range where the through-focus curve exceeds a predefined modulation transfer value). The method was shown to be accurate by using previously published contrast sensitivity data and wave-front analysis data. The applicability of the method was illustrated by applying the method to wave-front analysis measurements performed in pseudophakic patients with aspheric and spherical intraocular lenses. (C) 2010 Optical Society of Americ
Labelled Dataset of Retinal Images for Glaucoma detection
No full textFundus photography is a viable option for glaucoma population screening. In order to facilitate the development of computer-aided glaucoma detection systems, we publish this annotation dataset that contains manual annotations of glaucoma features for seven public fundus image data sets. All manual annotations are made by a specialised ophthalmologist. For each of the fundus images in the seven fundus datasets, the upper, the bottom, the left and the right boundary coordinates of the optic disc and the cup are stored in a .mat file with the corresponding fundus image name.
The seven public fundus image data sets are:
CHASEDB (https://blogs.kingston.ac.uk/retinal/chasedb1/),
Diaretdb1_v_1_1 (https://www.it.lut.fi/project/imageret/diaretdb1/),
DRINSHTI (http://cvit.iiit.ac.in/projects/mip/drishti-gs/mip-dataset2/Home.php),
DRIONS-DB (http://www.ia.uned.es/~ejcarmona/DRIONS-DB.html),
DRIVE (https://www.isi.uu.nl/Research/Databases/DRIVE/),
HRF (https://www5.cs.fau.de/research/data/fundus-images/), and
Messidor (http://www.adcis.net/en/Download-Third-Party/Messidor.html).
Researchers are encouraged to use this set to train or validate their systems for automatic glaucoma detection. When you use this set, please cite our published paper:
J. Guo, G. Azzopardi, C. Shi, N. M. Jansonius and N. Petkov, "Automatic Determination of Vertical Cup-to-Disc Ratio in Retinal Fundus Images for Glaucoma Screening," in IEEE Access, vol. 7, pp. 8527-8541, 2019, doi: 10.1109/ACCESS.2018.2890544.
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Glaucoma progression detection with frequency doubling technology (FDT) compared to standard automated perimetry (SAP) in the Groningen Longitudinal Glaucoma Study
Full text linkPurpose: To determine the usefulness of frequency doubling perimetry (FDT) for progression detection in glaucoma, compared to standard automated perimetry (SAP). Methods: Data were used from 150 eyes of 150 glaucoma patients from the Groningen Longitudinal Glaucoma Study. After baseline, SAP was performed approximately yearly; FDT every other year. First and last visit had to contain both tests. Using linear regression, progression velocities were calculated for SAP (Humphrey Field Analyzer) mean deviation (MD) and FDT MD and the number of test locations with a total deviation probability below p Results: Mean (SD) follow-up was 6.4 (1.7) years; median (interquartile range [IQR]) baseline SAP MD -6.6 (-14.2 to -3.6) dB. On average 8.2 and 4.5 tests were performed for SAP and FDT, respectively. Median (IQR) MD slope was -0.16 (-0.46 to +0.02) dB/year for SAP and -0.05 (-0.39 to +0.17) dB/year for FDT. Mantel Haenszel chi-squares of SAP MD vs FDT MD and TD were 12.5 (p Conclusions: FDT may be a useful technique for monitoring glaucoma progression in patients who cannot perform SAP reliably
The Groningen Longitudinal Glaucoma Study. II. A prospective comparison of frequency doubling perimetry, the GDx nerve fibre analyser and standard automated perimetry in glaucoma suspect patients
No full textWe aimed to determine prospectively the incidence of abnormal test results on frequency doubling perimetry (FDT), the nerve fibre analyser (GDx) and standard automated perimetry (SAP) in a cohort of glaucoma suspect patients with normal findings for all these tests at baseline. Seventy glaucoma suspect patients were followed prospectively for 4 years with SAP (Humphrey field analyser 30-2 SITA Fast), FDT (C-20 full-threshold) and GDx (Version 2.010) in a clinical setting. All patients had normal baseline test results on SAP, FDT and GDx. After the follow-up period, the number of patients who converted (whose test results changed from normal at baseline to reproducibly abnormal during follow-up) were counted for each technique and then compared. The cut-off point for FDT was > 1 depressed test-point p 29. Of the 70 glaucoma suspect patients, three converted on FDT, 14 on GDx and six on SAP. These proportions are significantly different for GDx versus SAP (p = 0.033) and GDx versus FDT (p = 0.002), but not for FDT versus SAP (p = 0.256). The most frequent finding after a 4-year follow-up was conversion on GDx
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