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Konrad Pesudovs is Foundation Professor and Chair of Discipline of Optometry and Vision Science at Flinders University. His main research interest is ophthalmology outcomes research; incorporating optical, visual and patient-centred measurement into the holistic measurement of outcomes in ophthalmology.
Browsing Konrad Pesudovs by Subject "Cataract"
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ItemA Critical Flicker Fusion (CFF) test of potential vision [Post print](Elsevier, 2007-02) Shankar, Hema ; Pesudovs, KonradPurpose: To continue developing a potential vision test based on the critical flicker fusion (CFF) phenomenon by using a brighter stimulus and optimizing its size. Setting: The Flinders Eye Centre of the Flinders Medical Centre, Flinders University, South Australia. Methods: A prospective, non-randomized study with 225 participants (134 females, 59.8%; mean age 71.4!13.2 yrs) assigned to four groups: normal (n=41), media opacity only (n=61), retinal/neural disease only (n=61), and cataract plus retinal/neural disease (n=61). Participants were recruited into these groups if aged over 20 years, but were excluded if they had any neurological disorder or medication known to affect CFF. CFF thresholds were measured for three stimulus sizes (0.5°, 1.0°, 1.5°). Discrimination between groups was tested with ANOVA and Receiver Operating Characteristic (ROC) analysis. The relationship between visual acuity (VA) and CFF in eyes without media opacity was determined with linear regression and used to predict visual outcome of 23 eyes undergoing cataract surgery. Results: CFF thresholds were reduced in retinal/neural disease but resistant to image degradation from media opacity. The 1.5° stimulus had 88% sensitivity and 90% specificity for discriminating groups. Post-cataract surgery VA was accurately predicted within ±1 line in 43%, ±2 lines in 83% and ±3 lines in 100% of eyes All eyes with poor VA (>0.50 logMAR) or dense cataract (>4.0 LOCSIII) were predicted within ±2 lines. Conclusion: CFF effectively discriminates between subjects with and without retinal/neural disease and accurately predicts visual outcome after cataract surgery. The use of a brighter stimulus enhanced performance in dense media opacity.
ItemAn instrument for assessment of subjective visual disability in cataract patients(BMJ Publishing Group - http://bjo.bmjjournals.com/, 1998) Pesudovs, Konrad ; Coster, Douglas JohnThe construction and validation of an instrument for the assessment of subjective visual disability in the cataract patient is described. This instrument is specifically designed for measuring the outcome of cataract surgery with respect to visual disability. METHODS: Visually related activities thought to be affected by cataract were considered for the questionnaire. These were reduced by pilot study and principal components analysis to 18 items. A patient's assessment of his/her ability to perform each task was scored on a four point scale. Scores were averaged to create an overall index of visual disability, as well as subscale indices for mobility related disability, distance/lighting/reading related disability, and near and related tasks visual disability. The questionnaire, administered verbally is entitled "The Visual Disability Assessment (VDA)". Reliability testing included test-retest reliability, interobserver reliability (p, the intraclass correlation coefficient), and internal consistency reliability (Cronbach's alpha). Construct validation, the process for proving that a test measures what it is supposed to measure, included consideration of content validity, comparison with the established Activities of Daily Vision Scale (ADVS) and empirical support with factor analysis. RESULTS: For the four indices, interobserver reliability varied from 0.92 to 0.94, test-retest reliability varied from 0.96 to 0.98, and internal consistency reliability varied from 0.80 to 0.93. The VDA compared favourably with the ADVS by correlation, but Bland-Altman analysis demonstrated that the two instruments were not clinically interchangeable. Factor analysis suggests that all test items measure a common theme, and the subgroupings reflect common themes. CONCLUSIONS: The VDA is easy to administer because it has a short test time and scoring is straightforward. It has excellent interobserver, test-retest, and internal consistency reliability, and compares favourably with the ADVS, another test of visual disability. Factor analysis demonstrated that the 18 items measure a related theme, which can be assumed to be visual disability. The VDA is a valid instrument which provides a comprehensive assessment of visual disability in cataract patients and is designed to detect changes within a patient over time.
ItemRefractive error changes in cortical, nuclear, and posterior subcapsular cataracts(BMJ Publishing Group - http://bjo.bmjjournals.com/, 2003-08) Pesudovs, Konrad ; Elliott, David BAIMS: To determine the effect of the three main morphological types of cataract on refractive error. METHODS: Data were prospectively collected from 77 subjects (age 67 (SD 8) years) with one morphological type of cataract. 34 had cortical, 21 had nuclear, and 21 had posterior subcapsular cataract. 22 subjects with clear lenses (60 (7) years) were recruited as controls. The spherical equivalent and astigmatic vector change between spectacle correction and optimal refraction were calculated. RESULTS: The cortical cataract group showed a significant astigmatic change of 0.71 (0.67) D (mean (1 SD)) compared to the control group (0.24 (0.20) D), with 24% outside the 95% confidence limit (0.63 D). The nuclear cataract group showed a significant myopic shift of -0.38 (0.60) D compared to the control group (+0.02 (0.21) D), with 52% beyond the minus 95% confidence limit (-0.39 D). CONCLUSION: A quarter of subjects with cortical cataract showed larger changes in astigmatism than subjects with clear lenses. This is probably because of the localised refractive index changes along cortical spoke opacities within the pupillary area. The well known myopic shift of nuclear cataract was also demonstrated.
ItemThe usefulness of Vistech and FACT contrast sensitivity charts for cataract and refractive surgery outcomes research(BMJ Publishing Group - http://bjo.bmjjournals.com/, 2004-01) Pesudovs, Konrad ; Hazel, Charlotte A ; Doran, Robert M L ; Elliott, David BAIM: To investigate the repeatability and sensitivity of two commonly used sine wave patch charts for contrast sensitivity (CS) measurement in cataract and refractive surgery outcomes. METHODS: The Vistech CS chart and its descendant, the Functional Acuity Contrast Test (FACT), were administered in three experiments: (1) Post-LASIK and age matched normal subjects; (2) Preoperative cataract surgery and age matched normal subjects; (3) Test-retest repeatability data in normal subjects. RESULTS: Contrast sensitivity was similar between post-LASIK and control groups and between the Vistech and FACT charts. The percentage of subjects one month post-LASIK achieving the maximum score across spatial frequencies (1.5, 3, 6, 12, 18 cycles per degree) were (50, 33, 13, 13, 0 respectively) for FACT, but only (0, 0, 13, 4, 0 respectively) for Vistech. A small number of cataract patients also registered the maximum score on the FACT, but up to 60% did not achieve the minimum score. Test-retest intraclass correlation coefficients varied from 0.28 to 0.64 for Vistech and 0.18 to 0.45 for FACT. Bland-Altman limits of agreement across spatial frequencies were between +/-0.30 and +/-0.85 logCS for Vistech, and +/-0.30 to +/-0.75 logCS for FACT. DISCUSSION: The Vistech was confirmed as providing poorly repeatable data. The FACT chart, likely because of a smaller step size, showed slightly better retest agreement. However, the reduced range of scores on the chart due to the smaller step size led to ceiling (post-LASIK) and floor (cataract) effects. These problems could mask subtle differences between groups of patients with near normal visual function as found post-refractive or cataract surgery. The Vistech and FACT CS charts are ill suited for refractive or cataract surgery outcomes research.