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Konrad Pesudovs

Publications and source records attributed to Konrad Pesudovs.

At least 19 recordsLinked to original sources
PubMed2006

Patient-centred measurement in ophthalmology--a paradigm shift.

Ophthalmologists and researchers in ophthalmology understand what a rapidly evolving field ophthalmology is, and that to conduct good research it is essential to use the latest and best methods. In outcomes research, one modern initiative has been to conduct holistic measurement of outcomes inclusive of the patient's point of view; patient-centred outcome. This, of course, means including a questionnaire. However, the irony of trying to improve outcomes research by being inclusive of many measures is that the researcher may not be expert in all measures used. Certainly, few people conducting outcomes research in ophthalmology would claim to be questionnaire experts. Most tend to be experts in their ophthalmic subspecialty and probably simply choose a popular questionnaire that appears to fit their needs and think little more about it. Perhaps, unlike our own field, we assume that the field of questionnaire research is relatively stable. This is far from the case. The measurement of patient-centred outcomes with questionnaires is a rapidly evolving field. Indeed, over the last few years a paradigm shift has occurred in patient-centred measurement.

Humans↗
PubMed2006

The efficacy of a nurse-led preoperative cataract assessment and postoperative care clinic.

OBJECTIVE: To describe the implementation of a nurse-led preoperative cataract assessment and postoperative care clinic and to assess the safety, efficacy and outcomes. DESIGN, SETTING AND PARTICIPANTS: A prospective study involving 185 public patients (221 eyes) referred to the Department of Ophthalmology at Flinders Medical Centre for cataract surgery. The study was conducted between February 2003 and August 2004. INTERVENTIONS: Patients were assessed in the nurse-led preoperative assessment clinic. Those deemed suitable for cataract surgery were also assessed by an ophthalmologist and underwent cataract surgery if appropriate. The nurse managed postoperative care. MAIN OUTCOME MEASURES: Concordance between nurse practitioner and ophthalmologist assessments; waiting times for first clinic appointment and surgery; visual acuity and degree of visual disability; patient satisfaction. RESULTS: 114 patients (61.6%) were assigned to see the ophthalmologist for cataract surgery. Median waiting times fell from 115 days (range, 23-268 days) to 21 days (range, 9-43 days) for initial clinic appointment, and from 44 days (range, 5-148 days) to 29 days (range, 14-154 days) for surgery. All 114 patients were listed for cataract surgery, and surgery had been performed on 121 eyes by the end of the study. After surgery, visual acuity improved by a mean of 0.45 logMAR (logarithm of the minimal angle of resolution) (SD, 0.24; range, 0.08-1.32). All patients had improved visual ability and high levels of satisfaction. Three quality assurance evaluations demonstrated full concordance between nurse and ophthalmologist assessments. CONCLUSIONS: Implementing a nurse-led cataract assessment clinic improved access to care for public patients with cataracts. The safety and efficacy of the program and its excellent visual and patient-centred outcomes commend its adaptation and implementation to other ophthalmology departments.

Aged↗
PubMed2006

Influence of photodynamic therapy for age related macular degeneration upon subjective vision related quality of life.

BACKGROUND: Photodynamic therapy (PDT) has been used in the treatment of choroidal neovascularisation secondary to age-related macular degeneration (AMD). This study prospectively investigated patients' subjective change in visual function following PDT as treatment for AMD. METHODS: Eighty-two consecutive patients receiving PDT in Tasmania, Australia, between May and November 2003 were recruited. In conjunction with a comprehensive clinical examination, the Visual Function-14 (VF-14) questionnaire was administered. Final follow-up occurred between February and March 2005. The VF-14 was scored by traditional summary scoring and by Rasch analysis. RESULTS: Five of the 82 (6.1%) subjects recruited were excluded from analysis. PDT was performed on average 5.7+/-2.6 times per patient. Raw VF-14 scores tended towards being significantly lower at follow-up than at baseline (67.6+/-27.2 against 64.5+/-27.7; P=0.052), and did significantly deteriorate using a collapsed Rasch analysis (P=0.0102). Following treatment, 38 (47.5%) eyes had lost three or more Snellen lines of best-corrected visual acuity. CONCLUSION: Patients undergoing PDT typically report reasonable visual function. In parallel with visual acuity, self-reported visual function may deteriorate slightly after PDT for AMD, but not as much as reported in untreated AMD.

Aged↗
PubMed2006

Sarcoidosis: case report and review.

Sarcoidosis is a granulomatous disorder of uncertain aetiology that can affect almost any organ. Anterior uveitis is a feature of the condition in about 30 per cent of those affected. We describe a patient with sarcoidosis presenting with anterior uveitis and describe a diagnostic approach. Sarcoidosis is a condition that must be considered in patients presenting with symptomatic uveitis, as the underlying disease is serious and usually treatable. The diagnosis of sarcoidosis is aided by an understanding of the pattern of organ involvement and may ultimately require tissue confirmation through biopsy of granulomata, including those found in the ocular adnexa.

Adult↗
PubMed2006

The Contact Lens Impact on Quality of Life (CLIQ) Questionnaire: development and validation.

PURPOSE: To develop and validate a questionnaire for the measurement of the impact of contact lenses on quality of life (QoL): The Contact Lens Impact on Quality of Life (CLIQ) Questionnaire. METHODS: The questionnaire was developed and validated using conventional methods and Rasch analysis to assure content validity, repeatability, construct validity, and low respondent burden. Item identification and selection (647 items) were performed with an extensive literature review, professional advice, and lay focus groups. Item reduction used focus groups and data obtained from 161 subjects completing a 90-item pilot questionnaire. Validity and reliability, from data of 128 additional subjects, were assessed using Rasch analysis, intraclass correlation coefficient, and Bland-Altman limits of agreement. RESULTS: A 28-item CLIQ Questionnaire was developed and shown to have good validity and reliability by Rasch analysis statistics: real person separation, 2.02; model person separation, 2.17; reliability, 0.80; root mean square measurement error, 2.73; mean square+/-SD infit, 1.01+/-0.18; outfit, 1.01+/-0.19. The items (mean score, 49.8+/-4.9) were well targeted to the subjects (mean score, 51.2+/-6.2) with a mean difference of 1.35 (scale range, 0-100) units. Test-retest intraclass correlation coefficient (0.86) and coefficient of repeatability (+/-8.00 units) demonstrated good repeatability. CONCLUSIONS: Rasch analysis and standard psychometric analyses demonstrated that the 28-item CLIQ Questionnaire is a valid and reliable measure of QoL in contact lens wearers. A scoring algorithm is provided for CLIQ Questionnaire users to convert raw scores into the Rasch analysis-derived linear person measures.

Adolescent↗
PubMed2006

The Impact of Vision Impairment Questionnaire: an evaluation of its measurement properties using Rasch analysis.

PURPOSE: To explore the psychometric properties of the Impact of Vision Impairment scale (IVI) by using Rasch analysis. METHODS: Three hundred fourteen first-time referrals to low-vision clinics completed the 32-item IVI. The data were Rasch-analyzed with a partial credit model using RUMM2020 software (RUMM Laboratory, Perth, WA, Australia). The overall fit of the model, response scale, individual item fit, differential item functioning, unidimensionality, and person-separation reliability were assessed. RESULTS: Initially, 26 items displayed disordered thresholds. However, collapsing the response scale to three categories (4 items) and four categories (28 items) produced ordered response thresholds for all items. Four items with high proportions of missing responses, poor spread, high skewness, and deviation between observed and expected model curves were then removed. This adjustment produced overall fit to the Rasch model (item-trait interaction chi(2) = 118.3; P = 0.32). The final mean (SD) person and item fit residuals ere 0.06 (0.85) and -0.20 (1.45), respectively. The person-separation reliability was 0.9, indicating that the scale was able to discriminate between several different groups of participants. The revised scale was well targeted to the participants, with similar mean locations for items (0.00) and persons (0.16). A significant difference between participants of mild, moderate, and severe visual impairment (ANOVA; P 0.001) supported the criterion validity of the Rasch-scaled IVI. CONCLUSIONS: The results provide support for the measurement properties of the Rasch-scaled 28-item version of the IVI and of its potential for assessing outcomes of low-vision rehabilitation. A raw score-to-Rasch person measure conversion is supplied.

Adult↗
PubMed2006

Impact of Zernike-fit error on simulated high- and low-contrast acuity in keratoconus: implications for using Zernike-based corrections.

This study examines the extent to which a Zernike-based optical correction can restore acuity in keratoconus as a function of disease severity and contrast level. Increasingly complete Zernike corrections in the presence of Zernike-fit error were simulated. Acuity for keratoconic eyes with <60 D maximum corneal power reached 20/13 with a fifth-order Zernike correction under high-contrast conditions and exhibited a loss of 0.1 logMAR (minimum angle of resolution) (from 20/32 to 20/40) for low-contrast conditions. Acuity for keratoconic eyes with >60 D maximum corneal power approached 20/13 with sixth-tenth-order corrections under high-contrast conditions but did not return to similar levels with a tenth-order correction for low-contrast conditions. The results suggest that fit error affects visual performance for more difficult tasks and that restoring high-contrast acuity (20/16 or better) using a fifth-order Zernike correction is not limited by Zernike=fit error for over 88% of keratoconus cases.

Computer Simulation↗
PubMed2006

Corneal first surface wavefront aberrations before and after pterygium surgery.

PURPOSE: To determine the higher order aberrations at the corneal first surface before and after surgery for pterygium. METHODS: Data were drawn from a longitudinal study of patients undergoing pterygium excision at Royal Victoria Infirmary, Newcastle upon Tyne, England between September 1998 and May 2004. Corneal topography was taken with the TMS-2 Topographic Modeling System (Computed Anatomy Corp) prior to and 6 months after surgery, exported to VOLPro software v7.08 (Sarver & Associates), and wavefront aberrations were derived for a 5.0-mm pupil using a 10th order Zernike polynomial expansion. Pre- to postoperative changes were assessed for significance using analyses of variance, and the relative risk of significant postoperative aberrations by pterygium size was determined. RESULTS: Satisfactory corneal topography was available on 67 eyes (mean age 53.8 +/- 16.7 years [range: 25-86 years]). The root-mean-square (RMS) fit error in preoperative eyes was 0.15 +/- 0.10 microm. Preoperatively, the total higher order RMS wavefront aberration was 0.94 +/- 0.83 microm. All Zernike modes were elevated, with trefoil being the major contributor 0.52 +/- 0.50 microm. Pterygium excision significantly reduced wavefront aberrations across all modes and orders (F(1, 129) = 6.7 to 22.6, P < .01): total higher order RMSpostop 0.45 +/- 0.35 microm. Cases with visually significant postoperative aberrations occurred and were more likely with larger pterygia: relative risk compared to pterygia 1.0 to 1.9 mm was 1.3 for 2.0 to 2.9 mm, 8.5 for 3.0 to 3.9 mm, 13.3 for 4.0 to 4.9 mm, and 10.2 for 5.0 to 5.9 mm. CONCLUSIONS: Zernike polynomial fitting well describes wavefront aberrations in eyes with pterygia. Pterygia are associated with wavefront aberrations, especially trefoil, but these were largely eliminated by surgery. Earlier excision of pterygia reduces the likelihood of significant residual aberrations.

Adult↗
PubMed2006

Penetrating keratoplasty for keratoconus: the nexus between corneal wavefront aberrations and visual performance.

PURPOSE: To compare the visual and optical performance after penetrating keratoplasty (PK) for keratoconus to normal patients and to examine the relationship between corneal wavefront aberrations and visual performance in patients with PK. METHODS: Visual performance testing, with optimal refractive correction, included low contrast visual acuity (LCVA) and Pelli-Robson contrast sensitivity with and without glare, and high contrast visual acuity. Corneal first surface wavefront aberrations were calculated from EyeSys topography data using VOL-Pro software v7.00 for a 4.0-mm pupil as a 10th order Zernike expansion and converted into single value metrics. Normal patients were compared to patients with PK using analysis of variance, and linear regression was used to compare wavefront aberration metrics to visual performance. RESULTS: Patients with PK (n=14, age 41.6 +/- 7.0 years) and normal patients (n=14, age 36.7-9.0 years) were of similar age (F(1, 26) = 2.54, P = .12). Normal patients saw significantly better on all visual performance measures and had better optical performance for total higher order root-mean-square corneal wavefront aberration (mean-SD): PK, 0.67 +/- 0.41 microm; normal, 0.09 +/- 0.02 microm (F(1,26) = 28.41, P < .001) and across all Zernike orders and modes. Wavefront aberrations in PK eyes were dominated by trefoil 0.35 +/- 0.27 microm, coma 0.47 +/- 0.37 microm, spherical aberration 0.17 +/- 0.10 microm, and tetrafoil 0.12 +/- 0.07 microm. The relationships between corneal wavefront aberration and visual performance metrics were strongest for LCVA = 0.30-0.98 Pupil fraction for wavefront (tessellation) -0.04 Half width at half height, R2=0.75. CONCLUSIONS: In this series, patients with PK had poorer visual performance compared to normal patients, which is due to increased corneal wavefront aberrations. Outcomes research in corneal transplantation should include measurement of wavefront aberrations and visual performance in the contrast domain.

Adult↗
PubMed2006

Recall from informed consent counselling for cataract surgery.

The authors investigated the effect of giving written material on information recall from informed consent counselling for cataract surgery. Fifty English-speaking patients who underwent non-urgent cataract extraction at Flinders Medical Centre, South Australia, were prospectively enrolled. Systematic counselling for cataract surgery was provided, with a written copy of the content given to a randomly selected group of patients (n = 24). All subjects completed a questionnaire after counselling and again at two weeks after surgery to test their satisfaction with, and recall of, information provided. Patients were found to be satisfied with the amount of information they received and most were able to recall details about the cataract surgery procedure. However, many could not recall success rates or complication rates and only a minority could list any complication. The provision of written information did not significantly alter recall (p>0.05). Recall was significantly better immediately after counselling than two weeks after surgery (p<0.05). Younger patients also had significantly better recall (p<0.05). Patients were happy with the information they had been given but did not remember enough from the informed consent process to satisfy legal requirements.

Aged↗
PubMed2005

The Refractive Status and Vision Profile: evaluation of psychometric properties and comparison of Rasch and summated Likert-scaling.

The psychometric properties of the Refractive Status and Vision Profile (RSVP) questionnaire were evaluated using Rasch analysis. Ninety-one myopic patients from a refractive surgery clinic and general optometric practice completed the RSVP. Rasch analysis of the RSVP ordinal data was performed to examine for unidimensionality and item reduction. The traditional Likert-scoring system was compared with a Rasch-scored RSVP and a reduced item Rasch-scored RSVP. Rasch analysis of the original RSVP showed poor targeting of item difficulty to patient quality of life, items with a ceiling effect and underutilized response categories. Combining the underutilized response scales and removal of redundant and misfitting items improved the internal consistency and targeting of the RSVP, and the reduced 20-item Rasch scored RSVP showed greater relative precision over standard Likert scoring in discriminating between the two subject groups. A Rasch scaled quality of life questionnaire is recommended for use in refractive outcomes research.

Adult↗
PubMed2005

Effect of cataract surgery incision location and intraocular lens type on ocular aberrations.

PURPOSE: To determine whether Hartmann-Shack wavefront sensing detects differences in optical performance in vivo between poly(methyl methacrylate) (PMMA) and foldable acrylic intraocular lenses (IOLs) and between clear corneal and scleral tunnel incisions and whether optical differences are manifested as differences in visual performance. SETTING: Department of Optometry, University of Bradford, West Yorkshire, United Kingdom. METHODS: This study comprised 74 subjects; 17 were phakic with no ocular pathology, 20 had implantation of a Pharmacia 722C PMMA IOL through a scleral tunnel, 21 had implantation of an Alcon AcrySof IOL through a scleral tunnel, and 16 had implantation of an AcrySof IOL through a corneal incision. Visual acuity and contrast sensitivity testing, ocular optical quality measurement using Hartmann-Shack wavefront sensing, and corneal surface measurement with a videokeratoscope were performed in all cases. RESULTS: There were significant differences between groups in the total root-mean-square (RMS) wavefront aberration over a 6.0 mm pupil (F=3.91; degrees of freedom=3,70; P<.05) mediated at the 4th-order RMS, specifically spherical and tetrafoil aberrations. The PMMA-scleral group had the least aberrations and the AcrySof-corneal group the most. For a 3.5 mm diameter pupil, the total higher-order RMS wavefront aberration was not significantly different between the groups (P>.05). There were no differences between groups in corneal shape, visual acuity, or contrast sensitivity. CONCLUSIONS: Implantation of the spherical PMMA IOL led to a slight reduction in total wavefront aberration compared to phakic eyes. AcrySof IOLs induced more aberrations, especially spherical aberration. Corneal-based incisions for IOL implantation compounded this increase. Studies of the optical performance of IOLs in vivo should use wavefront sensing as the main outcome measure rather than visual measures, which are readily confounded by multiple factors.

Acrylic Resins↗
PubMed2005

Changes in quality of life after laser in situ keratomileusis for myopia.

PURPOSE: To measure quality of life (QoL) outcome in prepresbyopic myopic patients having laser in situ keratomileusis (LASIK) refractive surgery using the Quality of Life Impact of Refractive Correction (QIRC) questionnaire and to compare the QoL of preoperative patients with a sample of spectacle and contact lens wearers not considering refractive surgery. SETTING: Department of Optometry, University of Bradford, Bradford, and Ultralase, Leeds, West Yorkshire, United Kingdom. METHODS: The validated QIRC questionnaire was prospectively completed by 66 patients before and 3 months after LASIK. Patients had myopia greater than 0.50 diopters (D) (range --0.75 to --10.50 D) and were aged 16 to 39 years. Patients were also directly asked to evaluate their QoL after surgery. RESULTS: Overall QIRC scores improved after LASIK from a mean of 40.07+/- 4.30 (SD) to 53.09+/- 5.25 (F(1,130)=172.65, P<.001). Greater improvements occurred in women (53.83+/- 5.46) than in men (49.39+/- 5.94; F(1,64)=9.37, P<.005). Overall, 15 of the 20 questions (especially convenience, health concerns, and well-being questions) showed significantly improved scores (P<.05). Patients who "strongly agreed" (53.96+/- 4.91, n=33) or "agreed" (51.78+/- 6.19, n=23) had improved QoL and had significantly higher QIRC scores than those who "neither agreed nor disagreed" (44.36+/- 4.97, n=5) or "strongly disagreed" (42.82, n=1) (F(1,60)=11.24, P<.001). The matched group not contemplating LASIK scored 42.41 +/- 3.89 on QIRC overall. CONCLUSIONS: Large improvements in QIRC QoL scores were found after LASIK for myopia in the majority of patients, with greater improvements in women. A small number of patients (4.5%) had decreased QIRC QoL scores, and these were associated with complications. People presenting for LASIK scored measurably poorer than matched patients not contemplating refractive surgery.

Adult↗
PubMed2005

Improving subjective scaling of pain using Rasch analysis.

UNLABELLED: Pain management outcomes assessment depends on valid measurement of pain. However, the validity of single-item scales, such as numeric or faces scales, with the assignment of ordinal numerical values to response scale categories, is questionable. The universal assumption that equal distances between response choices represent equal distances on the dimension being measured is essentially erroneous. Herein we demonstrate that Rasch analysis can be used to expose and repair scale inequity and reengineer scale structure. Thirty-one subjects with severe ocular surface disease repeatedly completed a 7-category faces pain scale. Rasch analysis demonstrated that response category 5 was underutilized, leading to disordering of the response scale. Collapsing category 5 into either category 4 or 6 produced an ordered 6-category faces scale that could be recalibrated with average Rasch person measures to create linear measurement on a continuous latent variable. The value of further alterations to the scale was explored, and the implication for scale redesign discussed. Rasch analysis could be applied to any subjective pain measure post-hoc to create linear measurement or applied during instrument development to optimize design. PERSPECTIVE: Single-item scales like the faces scale or a 1-10 numerical rating scale are commonly used for the subjective assessment of pain. However, scores applied to response categories are arbitrary, so do not represent equidistant steps in the underlying latent variable (pain). Scale inequities are easily demonstrable and repairable with Rasch analysis.

Adult↗