Josine van der Schoot

Het Oogziekenhuis Rotterdam, Rotterdam, South Holland, Netherlands

Are you Josine van der Schoot?

Claim your profile

Publications (10)24.6 Total impact

  • [Show abstract] [Hide abstract]
    ABSTRACT: To determine the ability of ophthalmologists across Europe to match stereoscopic optic disc photographs to visual fields of varying severity. Evaluation and comparison of 2 diagnostic tests. A total of 109 of 260 invited ophthalmologists in 11 European countries. These had participated in the previous European Optic Disc Assessment Trial (EODAT), a trial on glaucoma diagnostic accuracy based on optic discs only. Each participant matched stereo optic disc photographs of 40 healthy and 48 glaucomatous eyes to a visual field chosen from 4 options per disc. The 4 presented visual fields included the corresponding one and 3 other visual fields, varying in severity. The matching accuracy and any inaccuracy per disease severity were calculated. Classification accuracy (as glaucomatous or healthy) was compared with EODAT data. Duplicate slides allowed for the assessment of intraobserver agreement. Accuracy of matching optic discs with their corresponding visual field and of classifying them as healthy or glaucomatous; intraobserver agreement (κ). The overall accuracy of ophthalmologists for correctly matching stereoscopic optic disc photographs to their visual fields was 58.7%. When incorrectly matched, the observers generally overestimated the visual field severity (P < 0.001), notably in eyes with early glaucoma. The intraobserver agreement was, on average, moderate (0.52). European ophthalmologists correctly matched stereoscopic optic disc photographs to their corresponding visual field in only approximately 59% of cases. In most mismatches, the clinicians overestimated the visual field damage. Proprietary or commercial disclosure may be found after the references.
    Ophthalmology 06/2013; · 5.56 Impact Factor
  • K. A. Vermeer, J. van der Schoot, H. G. Lemij, J. F. de Boer
    [Show abstract] [Hide abstract]
    ABSTRACT: Recently, a method to determine the retinal nerve fiber layer (RNFL) attenuation coefficient, based on normalization on the retinal pigment epithelium, was introduced. In contrast to conventional RNFL thickness measures, this novel measure represents a scattering property of the RNFL tissue. In this paper, we compare the RNFL thickness and the RNFL attenuation coefficient on 10 normal and 8 glaucomatous eyes by analyzing the correlation coefficient and the receiver operator curves (ROCs). The thickness and attenuation coefficient showed moderate correlation (r=0.82). Smaller correlation coefficients were found within normal (r=0.55) and glaucomatous (r=0.48) eyes. The full separation between normal and glaucomatous eyes based on the RNFL attenuation coefficient yielded an area under the ROC (AROC) of 1.0. The AROC for the RNFL thickness was 0.9875. No statistically significant difference between the two measures was found by comparing the AROC. RNFL attenuation coefficients may thus replace current RNFL thickness measurements or be combined with it to improve glaucoma diagnosis.
    Proc SPIE 03/2013;
  • [Show abstract] [Hide abstract]
    ABSTRACT: Purpose. We present spatial retinal nerve fiber layer (RNFL) attenuation coefficient maps for healthy and glaucomatous eyes based on optical coherence tomography (OCT) measurements. Quantitative analyses of differences between healthy and glaucomatous eyes were performed. Methods. Peripapillary volumetric images of 10 healthy and 8 glaucomatous eyes were acquired by a Spectralis OCT system. Per A-line, the attenuation coefficient of the RNFL was determined based on a method that uses the retinal pigment epithelium as a reference layer. The attenuation coefficient describes the attenuation of light in tissue due to scattering and absorption. En-face maps were constructed and visually inspected. Differences between healthy and glaucomatous eyes were analyzed (Mann-Whitney U test), both globally (average values) and spatially (concentric and per segment). Results. RNFL attenuation coefficient maps of healthy eyes showed relatively high and uniform values. For glaucomatous eyes, the attenuation coefficients were much lower and showed local defects. Normal and glaucomatous average RNFL attenuation coefficients were highly significantly different (P < 0.0001) and fully separable. The RNFL attenuation coefficient decreased with increasing optic nerve head distance for both groups, with highly significant differences for all distances (P < 0.001). The angular dependency showed high superio- and inferiotemporal and low nasal values, with most significant differences superio- and inferiotemporally. Conclusions. Maps of RNFL attenuation coefficients provide a novel way of assessing the health of the RNFL and are relatively insensitive to imaging artifacts affecting signal intensity. The highly significant difference between normal and glaucomatous eyes suggests using RNFL attenuation coefficient maps as a new clinical tool for diagnosing and monitoring glaucoma.
    Investigative ophthalmology & visual science 08/2012; 53(10):6102-8. · 3.43 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: To determine effective and efficient monitoring criteria for ocular hypertension [raised intraocular pressure (IOP)] through (i) identification and validation of glaucoma risk prediction models; and (ii) development of models to determine optimal surveillance pathways. A discrete event simulation economic modelling evaluation. Data from systematic reviews of risk prediction models and agreement between tonometers, secondary analyses of existing datasets (to validate identified risk models and determine optimal monitoring criteria) and public preferences were used to structure and populate the economic model. Primary and secondary care. Adults with ocular hypertension (IOP > 21 mmHg) and the public (surveillance preferences). We compared five pathways: two based on National Institute for Health and Clinical Excellence (NICE) guidelines with monitoring interval and treatment depending on initial risk stratification, 'NICE intensive' (4-monthly to annual monitoring) and 'NICE conservative' (6-monthly to biennial monitoring); two pathways, differing in location (hospital and community), with monitoring biennially and treatment initiated for a ≥ 6% 5-year glaucoma risk; and a 'treat all' pathway involving treatment with a prostaglandin analogue if IOP > 21 mmHg and IOP measured annually in the community. Glaucoma cases detected; tonometer agreement; public preferences; costs; willingness to pay and quality-adjusted life-years (QALYs). The best available glaucoma risk prediction model estimated the 5-year risk based on age and ocular predictors (IOP, central corneal thickness, optic nerve damage and index of visual field status). Taking the average of two IOP readings, by tonometry, true change was detected at two years. Sizeable measurement variability was noted between tonometers. There was a general public preference for monitoring; good communication and understanding of the process predicted service value. 'Treat all' was the least costly and 'NICE intensive' the most costly pathway. Biennial monitoring reduced the number of cases of glaucoma conversion compared with a 'treat all' pathway and provided more QALYs, but the incremental cost-effectiveness ratio (ICER) was considerably more than £30,000. The 'NICE intensive' pathway also avoided glaucoma conversion, but NICE-based pathways were either dominated (more costly and less effective) by biennial hospital monitoring or had a ICERs > £30,000. Results were not sensitive to the risk threshold for initiating surveillance but were sensitive to the risk threshold for initiating treatment, NHS costs and treatment adherence. Optimal monitoring intervals were based on IOP data. There were insufficient data to determine the optimal frequency of measurement of the visual field or optic nerve head for identification of glaucoma. The economic modelling took a 20-year time horizon which may be insufficient to capture long-term benefits. Sensitivity analyses may not fully capture the uncertainty surrounding parameter estimates. For confirmed ocular hypertension, findings suggest that there is no clear benefit from intensive monitoring. Consideration of the patient experience is important. A cohort study is recommended to provide data to refine the glaucoma risk prediction model, determine the optimum type and frequency of serial glaucoma tests and estimate costs and patient preferences for monitoring and treatment. The National Institute for Health Research Health Technology Assessment Programme.
    Health technology assessment (Winchester, England). 06/2012; 16(29):1-271, iii-iv.
  • [Show abstract] [Hide abstract]
    ABSTRACT: To demonstrate the effect of glaucoma on the optical attenuation coefficient of the retinal nerve fiber layer (RNFL) in Spectral Domain Optical Coherence Tomography (SD-OCT) images. We analyzed images of the peripapillary areas in 10 healthy and 30 glaucomatous eyes (mild, moderate, and advanced glaucoma, 10 eyes each), scanned with the Spectralis OCT (Heidelberg Engineering GmbH, Dossenheim, Germany). To calculate the RNFL attenuation coefficient (μ(att)), determined by the scattering properties of the RNFL, we used a model that normalized the reflectivity of the RNFL by the retinal pigment epithelium. The analysis was performed at four preset locations at 1.3 and 1.7 mm from the center of the optic nerve head (ONH) (i.e., temporally, superiorly, nasally, and inferiorly) and on averages per eye. To assess the structure-function relationship, we correlated the μ(att) to the mean deviation (MD) in standard automated perimetry. The μ(att) of the RNFL decreased up to 40% with increasing disease severity, on average as well as in each location around the ONH (Jonckheere-Terpstra test, P < 0.019 in all tests). The μ(att) of the RNFL depended significantly on the location around the ONH in all eyes (Kruskal-Wallis test, P < 0.014) and was lowest nasally from the ONH. The μ(att) correlated significantly with the MD in SAP (R(2) = 0.337). The measurements clearly demonstrated that the μ(att) of the RNFL decreased with increasing disease severity. The RNFL attenuation coefficient may serve as a new method to quantify glaucoma in SD-OCT images.
    Investigative ophthalmology & visual science 03/2012; 53(4):2424-30. · 3.43 Impact Factor
  • K. A. Vermeer, J. van der Schoot, H. G. Lemij, J. F. de Boer
    [Show abstract] [Hide abstract]
    ABSTRACT: We demonstrate significantly different scattering coefficients of the retinal nerve fiber layer (RNFL) between normal and glaucoma subjects. In clinical care, SD-OCT is routinely used to assess the RNFL thickness for glaucoma management. In this way, the full OCT data set is conveniently reduced to an easy to interpret output, matching results from older (non- OCT) instruments. However, OCT provides more data, such as the signal strength itself, which is due to backscattering in the retinal layers. For quantitative analysis, this signal should be normalized to adjust for local differences in the intensity of the beam that reaches the retina. In this paper, we introduce a model that relates the OCT signal to the attenuation coefficient of the tissue. The average RNFL signal (within an A-line) was then normalized based on the observed RPE signal, resulting in normalized RNFL attenuation coefficient maps. These maps showed local defects matching those found in thickness data. The average (normalized) RNFL attenuation coefficient of a fixed band around the optic nerve head was significantly lower in glaucomatous eyes than in normal eyes (3.0mm-1 vs. 4.9mm-1, P<0.01, Mann-Whitney test).
    Proc SPIE 02/2012;
  • [Show abstract] [Hide abstract]
    ABSTRACT: To study early flow and revascularization in a free, autologous, retinal pigment epithelium (RPE)-choroid graft. This prospective cohort study used spectral domain-optical coherence tomography (SD-OCT) after RPE-choroid graft surgery in 12 patients. This SD-OCT was combined with fluorescein angiography (FA) and indocyanine green angiography (ICGA) in 5 patients. SD-OCT revealed that vessel diameter, number of vessels, and graft thickness increased in 10 of 12 patients, starting between 3 and 10 days after surgery. A subsequent decrease in thickness was found in all 10 patients, beginning as early as 8 days after surgery. Initially, the graft vessels were optically clearer than the underlying choroidal recipient vessels. Between 8 and 30 days after surgery, the optically clear vessels became gray, similar to the recipient choroid. FA and ICGA revealed perfusion in 4 of 5 patients between postoperative days 6 and 15. Between postoperative days 12 and 60, the entire choroidal structure of the graft was visible on ICGA. CONCLUSIONS; These data suggest that enlargement of vessel diameter, increase in the number of choroidal vessels, and graft thickening visualized by SD-OCT correspond with the ingrowth of afferent vessels, as demonstrated by ICGA. The subsequent establishment of efferent vessels results in flow, imaged as a change in color of the graft's vessels from optically clear to gray, graft thinning on SD-OCT, and complete revascularization on ICGA. SD-OCT, a noninvasive examination, can be used to demonstrate early graft perfusion in patients (trialregister.nl/trialreg/admin/rctview.asp number, NTR1768).
    Investigative ophthalmology & visual science 06/2011; 52(8):5881-6. · 3.43 Impact Factor
  • Source
    K A Vermeer, J van der Schoot, H G Lemij, J F de Boer
    [Show abstract] [Hide abstract]
    ABSTRACT: Current OCT devices provide three-dimensional (3D) in-vivo images of the human retina. The resulting very large data sets are difficult to manually assess. Automated segmentation is required to automatically process the data and produce images that are clinically useful and easy to interpret. In this paper, we present a method to segment the retinal layers in these images. Instead of using complex heuristics to define each layer, simple features are defined and machine learning classifiers are trained based on manually labeled examples. When applied to new data, these classifiers produce labels for every pixel. After regularization of the 3D labeled volume to produce a surface, this results in consistent, three-dimensionally segmented layers that match known retinal morphology. Six labels were defined, corresponding to the following layers: Vitreous, retinal nerve fiber layer (RNFL), ganglion cell layer & inner plexiform layer, inner nuclear layer & outer plexiform layer, photoreceptors & retinal pigment epithelium and choroid. For both normal and glaucomatous eyes that were imaged with a Spectralis (Heidelberg Engineering) OCT system, the five resulting interfaces were compared between automatic and manual segmentation. RMS errors for the top and bottom of the retina were between 4 and 6 μm, while the errors for intra-retinal interfaces were between 6 and 15 μm. The resulting total retinal thickness maps corresponded with known retinal morphology. RNFL thickness maps were compared to GDx (Carl Zeiss Meditec) thickness maps. Both maps were mostly consistent but local defects were better visualized in OCT-derived thickness maps.
    Biomedical Optics Express 06/2011; 2(6):1743-56. · 3.18 Impact Factor
  • K. A. Vermeer, J. van der Schoot, H. G. Lemij, J. F. de Boer
    [Show abstract] [Hide abstract]
    ABSTRACT: Volumetric scans of current SD-OCT devices can contain on the order of 50 million pixels. Due to this size and because quantitative measurements in these scans are often needed, automatic segmentation of these scans is required. In this paper, a fully automatic retinal layer segmentation algorithm is presented, based on pixel-classification. First, each pixel is augmented by intensity and gradient data from a local neighborhood, thereby producing a feature vector. These feature vectors are used as inputs for a support vector machine, which classifies each pixel as above or below each interface. Finally, a level set method regularizes the result, producing a smooth surface within the three-dimensional space. Volumetric scans of 10 healthy and 8 glaucomatous subjects were acquired with a Spectralis OCT. Each scan consisted of 193 B-scans, 512 A-lines per B-scan (5 times averaging) and 496 pixels per A-line. Two B-scans of each healthy subject were manually segmented and used to train the support vector machine. One B-scan of each glaucomatous subjects was manually segmented and used only for performance assessment of the algorithm. The root-mean-square errors for the normal eyes were 3.7, 15.4, 15.0 and 5.5 mum for the vitreous/retinal nerve fiber layer (RNFL), RNFL/ganglion cell layer, inner plexiform layer/inner nuclear layer and retinal pigment epithelium/choroid interfaces, respectively, and 5.5, 11.5, 9.5 and 6.2 mum for the glaucomatous eyes. Based on the segmentation, retinal and RNFL thickness maps and blood vessel masks were produced.
    Proc SPIE 02/2011;
  • Josine van der Schoot, Nicolaas J Reus, Thomas P Colen, Hans G Lemij
    [Show abstract] [Hide abstract]
    ABSTRACT: Short-wavelength automated perimetry (SWAP) has been claimed to predict conversion to glaucoma 3 to 4 years before standard automated perimetry (SAP) defects occur. This study compared the moment of glaucomatous conversion between SWAP and SAP. Prospective, longitudinal follow-up study. Four hundred sixteen subjects with ocular hypertension (intraocular pressure >/=22 and </=32 mmHg and normal visual fields). A Humphrey Field Analyzer (24-2 program; Carl Zeiss Meditec, Dublin, CA) was used to perform both SWAP and SAP. All participants were tested once every half year during 7 to 10 years or until the onset of conversion (study end point). The conversion to glaucoma was defined as a reproducible glaucomatous visual field defect in SAP. The moment of onset of a reproducible defect in SAP was compared with that in SWAP. Of the 416 initial participants, 24 eyes of 21 subjects showed conversion in SAP. Of these eyes, 22 did not show earlier conversion in SWAP than in SAP. Standard automated perimetry even showed earlier conversion than SWAP in 15 cases. In only 2 eyes did SWAP show earlier conversion by up to 18 months. These results do not support the notion that SWAP generally predicts conversion to glaucoma in SAP. Instead, SAP appears to be at least as sensitive to conversion as SWAP in a large majority of eyes. The author(s) have no proprietary or commercial interest in any materials discussed in this article.
    Ophthalmology 11/2009; 117(1):30-4. · 5.56 Impact Factor