Biomedical subjects

Nomdo M Jansonius

Publications and source records attributed to Nomdo M Jansonius.

14 recordsLinked to original sources

PubMed2006

Is diabetes mellitus a risk factor for open-angle glaucoma? The Rotterdam Study.

PURPOSE: To investigate whether diabetes mellitus is a risk factor for open-angle glaucoma (OAG). DESIGN: Prospective population-based cohort study. PARTICIPANTS: Participants ages > or =55 years from the Rotterdam Study, The Netherlands. METHODS: Participants at risk for incident OAG (iOAG) underwent at baseline (1990-1993) and follow-up (1997-1999) the same ophthalmic examination including intraocular pressure (IOP) measurement, visual field testing, and simultaneous stereo optic disc photography. At baseline, diabetes mellitus was defined as the use of antidiabetic medication and/or a random or postload glucose value > or =11.1 mmol/l. The diagnosis of OAG was made with an algorithm based on optic disc measures and visual fields, independent of the IOP. MAIN OUTCOME MEASURE: Incident OAG. RESULTS: In total, 3837 participants without OAG at baseline were reexamined. After a mean follow-up time of 6.5 years, iOAG developed in 87 persons. The relative risk of iOAG associated with baseline diabetes was 0.82 (0.33-2.05). After adjustment for age, gender, follow-up time, IOP, IOP-lowering treatment, body mass index, and systemic hypertension, the relative risk of iOAG was 0.65 (0.25-1.64). CONCLUSIONS: In this prospective population-based study, diabetes mellitus was not a risk factor for OAG.

Aged↗

PubMed2006

Influence of test reliability on the screening performance of frequency-doubling perimetry.

PURPOSE: To investigate the influence of test reliability on the screening performance of frequency-doubling perimetry (FDT). DESIGN: Cross-sectional study. METHODS: FDT sensitivity and specificity were calculated three times using three different strategies for handling unreliable (that is, >0 reliability indices outside normal limits) and unfeasible (that is, could not be completed) tests in 452 glaucoma patients from our outpatient department and 237 healthy subjects recruited outside the hospital. RESULTS: Unreliable (P = .01) and unfeasible (P < .001) tests occurred more frequently in glaucoma patients when compared with healthy subjects. Best screening performance was obtained by interpreting unreliable tests as if they were reliable and considering unfeasible tests as positive. With this strategy, sensitivity was 0.90 (95% confidence interval 0.87-0.93) and specificity 0.81 (95% confidence interval 0.76-0.86). CONCLUSIONS: Unreliable and unfeasible FDT tests appear to contain useful information.

Cross-Sectional Studies↗

PubMed2006

Atherosclerosis, C-reactive protein, and risk for open-angle glaucoma: the Rotterdam study.

PURPOSE: To test the hypotheses that atherosclerosis and elevated serum C-reactive protein (CRP) levels are risk factors for open-angle glaucoma (OAG). METHODS: In a prospective, population-based cohort study, all participants 55 years and older and at risk for incident OAG underwent, at baseline (1990-1993) and at follow-up (1997-1999), the same ophthalmic examination, including visual field testing and optic disc photography. Baseline atherosclerosis was assessed by means of echography of the carotid arteries, abdominal x-ray examination, and ankle-arm index; baseline serum CRP levels were used in the analyses. The diagnosis of OAG was based on an algorithm using optic disc measures and visual field loss. Odds ratios of OAG were computed with logistic regression analyses. Risk factors were categorized in tertiles and according to standard deviation. RESULTS: After a mean follow-up of 6.5 years, incident OAG was diagnosed in 87 of 3842 (2.3%) participants at risk for OAG. Carotid artery plaques, carotid intima-media thickness, aortic calcifications, ankle-arm index, and CRP levels were not significant risk factors for OAG. The odds ratio, given for the highest and lowest tertiles, for carotid plaques was 1.43 (95% confidence interval [CI], 0.68-2.99), for carotid intima-media thickness 0.86 (95% CI, 0.47-1.57), for aortic calcifications 1.02 (95% CI, 0.60-1.75), for ankle-arm index 0.69 (95% CI, 0.38-1.25), and for CRP 1.19 (95% CI, 0.68-2.07). CONCLUSIONS: In this prospective, population-based study, neither atherosclerosis nor serum CRP level was an important risk factor for OAG.

Aged↗

PubMed2005

Towards an optimal perimetric strategy for progression detection in glaucoma: from fixed-space to adaptive inter-test intervals.

BACKGROUND: The aim was to compare two perimetric strategies for progression detection in glaucoma. METHODS: Two perimetric strategies for progression detection were compared by means of a thought experiment in a theoretical cohort. In strategy I, visual field testing is performed with fixed-space inter-test intervals at a frequency of two tests per year. In strategy II, the frequency of visual field testing is set to one test per year as long as the fields are apparently unchanged, whereas as soon as progression is suspected, confirmation or falsification is performed within a short time span. Outcome measures were the time delay between the progression event and the diagnosis of definite progression, and the number of visual field tests performed per patient per year. RESULTS: Average time delay between the actual progression event and the final diagnosis of definite progression was 15 months in the case of strategy I and 6 months in the case of strategy II. Maximum time delays were 18 and 12 months respectively. The frequency of visual field testing was 2 tests per patient per year for strategy I and 1.45 tests per patient per year for strategy II. CONCLUSIONS: Perimetry in glaucoma can be optimised by postponing the next test in the case of an apparently stable field and accelerating the next test in the case of a suspected progression. This results in an earlier diagnosis, a lower perimetric frequency and a shorter period of uncertainty for the patient.

Bayes Theorem↗

PubMed2005

Incidence of open-angle glaucoma in a general elderly population: the Rotterdam Study.

PURPOSE: To determine the incidence of open-angle glaucoma (OAG) in a general elderly white population. DESIGN: Population-based cohort study. PARTICIPANTS: Participants 55 years and older from the Rotterdam Study, The Netherlands. METHODS: Participants at risk for incident OAG underwent at baseline (1990-1993) and follow-up (1997-1999) the same ophthalmic examination, including measurement of intraocular pressure, visual field testing, and stereo optic disc photography. The diagnosis of probable or definite OAG was made with an algorithm based on optic disc parameters and on visual field testing, independent of the intraocular pressure. MAIN OUTCOME MEASURES: Five-year risk and incidence rates of OAG. RESULTS: In total, 3842 participants were examined (participation rate at follow-up, 78%). After a mean follow-up time of 6.5 years, probable (n = 58) or definite OAG (n = 29) developed in 87 persons. The 5-year risk of probable OAG was 1.2% and that of definite OAG 0.6%, and the rate rose for both together from 1% at age 60 years to approximately 3% at age 80 years. Bilateral OAG occurred 5 times more often after than before age 75 years. In participants with prevalent OAG in 1 eye, the 5-year risk of OAG in the fellow eye was 5 times higher than in fellow eyes of non-OAG eyes. Only 37% of the incident cases received treatment for OAG at the time of the reexamination. CONCLUSIONS: The incidence of OAG rose significantly with age. Most of the patients with incident OAG were unaware of having OAG.

Aged↗

PubMed2005

Three portable tonometers, the TGDc-01, the ICARE and the Tonopen XL, compared with each other and with Goldmann applanation tonometry*.

Three portable tonometers, the TGDc-01, the ICARE and the Tonopen XL, were compared with each other and to Goldmann applanation tonometry in a large group of healthy subjects and patients with ocular hypertension or glaucoma (n = 103). Measurements performed with the ICARE and the Tonopen XL were in good agreement with that of the Goldmann tonometer. Intraocular pressure (IOP) values measured with the TGDc-01 were significantly lower and showed more variability. The 95% limits of agreement (portable tonometer - Goldmann) were -17 to +10 mmHg for the TGDc-01, -6 to +7 mmHg for the ICARE and -6 to +8 mmHg for the Tonopen. Corneal thickness could not explain the differences between an IOP measured with the portable tonometers and an IOP measured with the Goldmann tonometer. Patient comfort was slightly higher for ICARE when compared with the Tonopen.

Adult↗

PubMed2005

The Groningen Longitudinal Glaucoma Study. I. Baseline sensitivity and specificity of the frequency doubling perimeter and the GDx nerve fibre analyser.

PURPOSE: To describe the baseline data of a large cohort of patients included for follow-up with perimetry using the frequency doubling technique (FDT) and with quantification of the retinal nerve fibre layer as assessed by GDx, and to calculate the sensitivity and specificity of both devices from these baseline data. METHODS: Regular visitors to our glaucoma service were included. All subjects were followed for at least 4 years with FDT in full-threshold mode, GDx and conventional perimetry. Patients were classified as having either glaucoma or suspect glaucoma, according to baseline perimetry results. In addition, a group of healthy subjects was recruited outside the hospital. RESULTS: A total of 452 glaucoma patients, 423 glaucoma suspects and 237 healthy subjects were incorporated into the analyses. Sensitivities for both FDT and GDx were fixed at 0.90. For the group as a whole, the specificity was 0.81 for FDT, using number of depressed test-points p < 0.01 in the total deviation probability plot with a cut-off point > 1, and 0.78 for GDx, using the Number, with a cut-off point > 29. The area under the receiver operating characteristic (ROC) curve was 0.92 for FDT and 0.94 for GDx. Of the subjects with suspect glaucoma, 75% showed normal FDT test results and 52% showed normal GDx results. Unlike FDT, GDx failed to detect some moderate/severe glaucoma cases. CONCLUSIONS: The performances of FDT and GDx are approximately equivalent in terms of sensitivity, specificity and area under the ROC curve. In glaucoma suspects, GDx in particular yielded a rather high percentage of positive test results. The majority of these positive test results are presumably false-positive results rather than results indicating preperimetric glaucoma.

Adolescent↗

PubMed2005

Strategies for improving the diagnostic specificity of the frequency doubling perimeter.

PURPOSE: To evaluate various strategies designed to improve the specificity of the interpretation of results obtained with the frequency doubling technology perimeter (FDT) used in the full-threshold mode. METHODS: Three different strategies were compared using data from 452 glaucoma patients and 237 healthy subjects: combining several FDT parameters from a single test, combining the FDT test with a GDx test, and confirming an abnormal FDT test result with a repeat test. RESULTS: Confirming an abnormal FDT test result with a repeat test yielded a specificity increase of 0.10, from 0.80 to 0.90, at the expense of some loss of sensitivity for early but not for moderate or severe glaucoma. Combining several FDT parameters from a single test and combining FDT with GDx did not yield any noticeable increase in diagnostic performance. CONCLUSIONS: A modest increase in FDT diagnostic performance can be obtained by the confirmation of an abnormal test result with a repeat test.

Cohort Studies↗

PubMed2004

Bayes' theorem applied to perimetric progression detection in glaucoma: from specificity to positive predictive value.

PURPOSE: To estimate the specificity of a clinical evaluation of a series of visual fields and to calculate the positive predictive value of progression. METHODS: The specificity of a clinical evaluation of a series of visual fields was estimated using nonparametric ranking and probability calculus. The positive predictive value of progression was calculated using Bayes' theorem. The literature suggests a prior probability of progression of typically 0.10 in the case of one visual field per year. Three different prior probability values were used: 0.05, 0.10, and 0.20. Calculations were performed for a sensitivity of 0.50, 0.80, and 1.00. RESULTS: Specificity of a clinical evaluation of a series of visual fields was calculated as 0.83 for four fields (two baseline fields, one follow-up field with suspected progression, and one confirmation of the suspected progression), 0.90 for five fields, and 0.95 for six fields. Positive predictive values ranged from 0.14 to 0.83. Positive predictive value was approximately 0.5 for a prior probability of 0.10, a sensitivity of 0.80, and a specificity of 0.90. CONCLUSIONS: Realistic series of visual fields that are apparently progressive have a positive predictive value of typically 0.5, i.e., half of them are stable. In the case of a high prior probability (uncontrolled glaucoma or long interval between successive fields), four fields may suffice to diagnose progression, whereas at least six fields are required if the prior probability is low.

Bayes Theorem↗

PubMed2004

Frequency doubling perimetry screening mode compared to the full-threshold mode.

The diagnostic performance of the frequency doubling perimetry (FDT) C20-1 screening mode was compared to that of the C20 full-threshold mode. For the number of defects p < 1% in the total deviation plot, both modes appeared to perform similarly in terms of sensitivity, specificity, and area under the receiver-operating characteristic (ROC) curve. Different cut-off points should be applied for both modes to obtain equal sensitivity and specificity values, and - related to that - for most subjects more defects were found in full-threshold mode than in screening mode. For the screening mode, we found a sensitivity of 0.91 and a specificity of 0.88 at a cut-off point of >0 defects, and an area under the ROC curve of 0.93.

Adult↗

PubMed2004

An evaluation of algorithms designed to classify the results from frequency doubling perimetry.

All previously published algorithms for the interpretation of frequency doubling perimetry test results were compared in full-threshold mode in a large group of glaucoma patients (n = 452) and normal subjects (n = 237). Areas under the receiver-operating characteristic (ROC) curve ranged from 0.86 to 0.92. None of the algorithms performed substantially better than simply counting the number of defects p < 1% in the total deviation plot. For this algorithm, we found a sensitivity of 0.90 and a specificity of 0.81 at a cut-off point of >1 defect, and an area under the ROC curve of 0.92.

Aged↗

PubMed2003

Effect of intraocular lens implantation on visual acuity, contrast sensitivity, and depth of focus.

PURPOSE: To determine the role of spherical and irregular aberrations in the optics of the natural eye and after intraocular lens (IOL) implantation in terms of visual acuity, contrast sensitivity, and depth of focus. SETTING: Laboratory of Experimental Ophthalmology, University of Groningen, Groningen, The Netherlands. METHODS: Visual acuity and defocus-specific contrast sensitivity in 11 pseudophakic patients (IOL group) and 27 age-matched phakic subjects were compared. The results were obtained psychophysically. Spherical and irregular aberrations were subsequently estimated by comparing the measured myopic shift (optimum focus of contrast sensitivity at 4 cycles per degree [cpd] compared to that at 16 cpd) and depth of focus with those of theoretical eye models with varying amounts of irregular and spherical aberrations. RESULTS: The best corrected visual acuity and best corrected contrast sensitivity in the IOL group did not significantly differ from that in the phakic group. The depth of focus was larger in the IOL group at a pupil diameter of 6.0 mm (P<.05). Comparison with theoretical eye models suggested a higher amount of spherical aberration in the IOL group; irregular aberration was almost the same in both groups. CONCLUSIONS: There was a higher amount of spherical aberration in the IOL group, related to a larger depth of focus, without loss of contrast sensitivity at optimum focus or loss of visual acuity. This might contribute to better quality of vision in pseudophakic subjects than in presbyopic phakic subjects.

Contrast Sensitivity↗

PubMed2003

Effect of methods of myopia correction on visual acuity, contrast sensitivity, and depth of focus.

PURPOSE: To psychophysically measure spherical and irregular aberrations in patients with various types of myopia correction. SETTING: Laboratory of Experimental Ophthalmology, University of Groningen, Groningen, The Netherlands. METHODS: Three groups of patients with low myopia correction (spectacles, soft contact lens, and Intacs) and 4 groups with high myopia correction (spectacles, rigid contact lens, Artisan claw lens, and laser in situ keratomileusis [LASIK]) had through-focus contrast sensitivity measurements to establish the myopic shift and depth of focus. From these 2 parameters, spherical and irregular aberrations were determined using theoretical eye models and geometric optics. Visual acuity, stray light, and predictability were also studied. RESULTS: There were no differences in best corrected visual acuity (BCVA) or best corrected contrast sensitivity between the low myopia groups. The Intacs group had a significantly larger depth of focus (P<.05). The results in the soft contact lens group were comparable to those in a human eye model with an average amount of spherical and irregular aberrations. The LASIK group had worse uncorrected visual acuity (UCVA) and best corrected contrast sensitivity than the spectacles, rigid contact lens, and Artisan claw lens groups (P<.05) due to the amount of spherical and irregular aberrations present after LASIK. The low and high myopia spectacles groups had average amounts of spherical and irregular aberrations. CONCLUSIONS: Neither surgical techniques nor contact lenses resulted in BCVA or best corrected contrast sensitivity that surpassed the values measured in the best corrected spectacles groups. The Artisan claw lens performed better than LASIK in UCVA, predictability, and best corrected contrast sensitivity.

Adult↗

PubMed2003

Learning effect, normal range, and test-retest variability of Frequency Doubling Perimetry as a function of age, perimetric experience, and the presence or absence of glaucoma.

The learning effect for several different Frequency Doubling Perimetry parameters was studied in full threshold mode in a large group of patients (n = 342) of various ages, with and without perimetric experience, and with and without glaucoma. A significant learning effect was only found for the mean deviation (MD) in aged normals without perimetric experience. The median of MD increased for both OD (from +0.2 to +1.0 dB) and for OS (from +0.5 to +1.3 dB). The effect disappeared largely during a third visit (median OD +1.2 dB, OS +1.3 dB). The normal range and the test-retest variability were measured in the same dataset. The learning effect for MD (1 dB or less) appeared to be small as compared with both the normal range (about 12 dB) and the test-retest variability (about 3 dB).

Adult↗