Biomedical subjects

Michaela Velikay-Parel

Publications and source records attributed to Michaela Velikay-Parel.

11 recordsLinked to original sources

PubMed2005

Biometry and refractive outcome of eyes filled with silicone oil by standardized echography and partial coherence interferometry.

BACKGROUND: We evaluated the validity of calculations for refractive outcome in cataract surgery in silicone oil-filled eyes. The retrosilicone space (RSS) was included in these calculations. METHODS: In a prospective study the axial length (AL) of silicone oil-filled eyes was measured. with standardized A-scan echography (SAE) and partial coherence interferometry (PCI). Meldrum's formula was used to transform the velocity of ultrasound within the vitreous cavity. To investigate whether refractive outcome can be calculated accurately, we assessed the difference between precalculated and final refractive outcome. Furthermore, we determined the advantages and disadvantages of SAE and PCI. A minor aim was to assess whether the AL of the two eyes differed significantly. RESULTS: In 85% of 117 eyes the difference between precalculated and postsurgical refraction was smaller than 1 diopter spherical and statistically not significant (p>0.2). The mean AL was 24.1 mm (range 20.0-31.4 mm). The difference in outcome between the two methods was without statistical significance: the AL difference was 0.4 (+/-2.6) mm on measurement with SAE and 0.04 (+/-0.46) mm with PCI. PCI has the advantage that it can be performed more easily, without contact, while echography is advantageous in the presence of advanced cataracts. In supine position an oil-free fluid space behind the silicone oil was detected with echography. The mean dimension of this space was 1.9 (+/-0.67) mm and it was taken into consideration for IOL calculation. The mean AL difference between the two eyes was 0.4 mm, but the difference was greater than 1 mm in 26% of the patients. CONCLUSION: The AL of eyes filled with silicone oil can be measured reliably with SAE and PCI. In supine position the RSS has to be considered to obtain more accurate IOL calculations.

Adolescent↗

PubMed2005

A method and technical equipment for an acute human trial to evaluate retinal implant technology.

This paper reports on methods and technical equipment to investigate the epiretinal stimulation of the retina in blind human subjects in acute trials. Current is applied to the retina through a thin, flexible microcontact film (microelectrode array) with electrode diameters ranging from 50 to 360 microm. The film is mounted in a custom-designed surgical tool that is hand-held by the surgeon during stimulation. The eventual goal of the work is the development of a chronically implantable retinal prosthesis to restore a useful level of vision to patients who are blind with outer retinal degenerations, specifically retinitis pigmentosa and macular degeneration.

Blindness↗

PubMed2005

Influence of laser in situ keratomileusis and laser epithelial keratectomy on patients' reading performance.

PURPOSE: To evaluate the influence of laser in situ keratomileusis (LASIK) and laser-assisted subepithelial keratectomy (LASEK) on reading performance regarding reading acuity, reading speed based on print size, maximum reading speed, and critical print size. SETTING: Department of Ophthalmology, University of Vienna, Vienna, and Auge-und-Laser, Medicent Baden, Austria. METHODS: Fifty-two eyes of 34 patients (26 eyes per group) were studied. Best corrected LogMAR visual acuity (Early Treatment Diabetic Retinopathy Study charts), reading acuity, and reading speed were tested monocularly before LASIK or LASEK and 3 weeks after surgery. Reading acuity (LogRAD) and reading speed were determined with the standardized Radner reading charts. RESULTS: Preoperatively, the distance visual acuity and reading acuity were comparable between the LASIK and LASEK patients. Reading speed measurements also showed no statistical difference. Three weeks after refractive surgery, no statistically significant differences in the preoperative measures and between the 2 surgical procedures could be found in any tested parameters. The mean distance visual acuity was LogMAR -0.02 +/- 0.06 (SD) (LASIK) and LogMAR -0.05 +/- 0.07 (LASEK). The mean reading acuity was LogRAD 0.00 +/- 0.12 (97.7% of LogMAR) (LASIK) and LogRAD 0.04 +/- 0.16 (93.7% of LogMAR) (LASEK). The mean maximum reading speed was 235 +/- 35 words per minute (LASIK) and 240 +/- 37 words per minute (LASEK), and the mean critical print size was at LogRAD 0.48 +/- 0.19 (LASIK) and 0.49 +/- 0.17 (LASEK). CONCLUSIONS: In a standardized reading test setting, no significant effects of LASIK and LASEK on individual reading performance could be evaluated. This indicates that patients can expect to retain their normal visual function after refractive surgery with these 2 procedures under full light conditions.

Adult↗

PubMed2004

The effect of specific gravity of perfluorocarbon liquid on the retina after experimental vitreous substitution.

PURPOSE: To evaluate the histological changes in the retina after experimental vitreous substitution with various amounts of perfluorophenanthrene (PFPH). METHODS: Thirty-two rabbit eyes were mechanically vitrectomized and filled up with 0.8 cc or 0.2 cc highly purified PFPH. The substance remained for 1 week (4 eyes), 2 weeks (8 eyes), 4 weeks (10 eyes) or 8 weeks (10 eyes). Eight eyes underwent the same surgical procedure without PFPH exchange to serve as a control group. A histological comparison of corresponding areas in the center and in the periphery of the inferior retina ensued. RESULTS: After 2 weeks, nuclear drop-downs and irregularities of the outer plexiform layer and of both nuclear layers were observed centrally in the eyes with a 0.8 cc substitution. The changes proceeded to irregularities and cell loss of all retinal layers with focal areas of complete destruction of the retinal architecture after 8 weeks. In contrast, single nuclear drop-downs, wrinkling of the outer nuclear layer and cell loss in the photoreceptor layer were observed in the peripheral retina at the end of the observation period. In those eyes where 0.2 cc PFPH was exchanged nuclear drop-downs were found after 2 weeks, leading to focal thinning of the outer plexiform layer and irregularities of the outer nuclear layer after 4 weeks with an insignificant increase after 8 weeks. At this time these histological alterations were comparable with those that we observed after 2 weeks in the eyes with a 0.8 cc tamponade in a corresponding area. CONCLUSIONS: Even high purification of PFPH does not prevent retinal damage. The different results in different areas after vitreous substitution with 0.2 cc and with 0.8 cc demonstrate that the high specific gravity of the substance may also play a role in the development of histological changes after extended tamponade.

Animals↗

PubMed2004

Proliferative vitreoretinopathy--at what risk is the fellow eye?

PURPOSE: To find out if patients with proliferative vitreoretinopathy (PVR) due to complicated retinal detachment are at risk to acquire the same disease or other vision-threatening retinal abnormalities in the fellow eye. To furthermore assess in what time-period they appear and if subgroups of patients have special risks. METHODS: 100 consecutive PVR-patients were studied retrospectively. 21 patients with PVR graded lower than C3, traumatic PVR, diabetic retinopathy or congenital vitreoretinal diseases were excluded. Age, gender, best-corrected visual acuity at the first and last visit, refraction, ocular disease in both eyes and observation-time were recorded. RESULTS: After a mean follow-up of 8.5 years, 42 of 79 patients (53.4%) showed vision-threatening abnormalities in their fellow eyes: among them, 9 patients (11.4%) had PVR, 13 (16%) simple retinal detachments and 14 (17.3%) retinal breaks. Abnormalities in the fellow eye did not develop after a certain time following surgery of the primary eye; 71.4% appeared within 5 years. Aphakic and pseudophakic patients had retinal breaks significantly more often (p = 0.011) than phakic patients. Myopia did not increase the risk for any abnormality. Men developed retinal detachment (p = 0.037) and PVR (p = 0.025) significantly more often than women. CONCLUSION: Patients with PVR have a greater than 50% risk of developing vision-threatening retinal abnormalities in their fellow eye. Because of this increased risk, these patients need regularly-scheduled long-term follow-up. SUMMARY STATEMENT: Patients with PVR have a greater than 50% risk of developing vision-threatening retinal abnormalities in their fellow eye and a 37% risk to develop PVR from rhegmatogenous retinal detachment. More than two thirds of abnormalities in the fellow eye developed within five years of surgery of the primary eye.

Adult↗

PubMed2004

Informed consent and decision making by cataract patients.

OBJECTIVES: To investigate decision making by patients on the day before cataract surgery and to evaluate to what extent the informed consent process influences the patients' decision regarding consent. METHODS: On the day before surgery, 70 patients (mean +/- SD age, 70.3 +/- 10.3 years) underwent a standardized informed consent procedure. They were also invited to answer 15 questions established in interdisciplinary cooperation among clinical psychologists, lawyers, and ophthalmologists. MAIN OUTCOME MEASURES: We assessed presurgical information and personal estimation of risks in cataract surgery; the patient-physician relationship regarding surgery-related decisions; and evaluations of the informed consent procedure and the patients' decision. RESULTS: Questionnaire answers indicated that 28 (40%) of the 70 participating patients arrived for surgery without any information; 16 (23%) believed that there were surgical procedures without risks; and 53 (76%) estimated that there were no risks for their cataract surgery. A physician-dominated decision for surgery was preferred by 31 patients (44%); 16 (26%) wanted to decide together with their ophthalmologist. Possible risks of a sight-threatening complication did not influence 54 patients' (77%) decisions, and 55 patients (78%) said the informed consent process did not influence their decision. The remaining 15 (22%) stated that the informed consent process positively confirmed their decision. CONCLUSIONS: Informed consent 1 day preoperatively does not seem to influence the decision for cataract surgery. Cognitive dissonance as part of a decision-making process makes changes in an already chosen option unlikely. The resulting limited decisive potential is very important for credibility in a trial and has to be considered in ophthalmologic surgery.

Aged↗

PubMed2004

Reading performance depending on the type of cataract and its predictability on the visual outcome.

PURPOSE: To investigate the influence of various types of cataract on reading performance in a standardized reading test setting. SETTING: Department of Ophthalmology, University of Vienna, Vienna, Austria. METHODS: The reading performance of 94 eyes with age-related cataract and normal macular function was evaluated with the Radner Reading Charts preoperatively and 4 weeks after cataract surgery. Distance visual acuity was tested with the ETDRS charts. Cataracts were graded using the Lens Opacities Classification System (LOCS) III, on which NO is nuclear opalescence and NC is nuclear color. RESULTS: Patients with pure nuclear cataracts (LOCS III: NO/NC 2.1-5) achieved a normally high MRS (99.84% +/- 7.65% of their postoperative MRS): preoperative MRS(1): 190.6 +/- 30.74 words per minute (wpm); postoperative MRS(2): 191.21 +/- 29.36 wpm. Patients with mixed nuclear-cortical cataracts (LOCS III: NO/NC 2.1-5; C>2) preoperatively achieved 96.96% +/- 5.6% of their postoperative MRS (MRS(1): 175.77 +/- 31.54 wpm; MRS(2): 181.34 +/- 30.56 wpm). In dense nuclear cataracts (LOCS III: NO/NC>5), the MRS was significantly reduced, achieving only 72.64 +/- 19.19% of the postoperative MRS (MRS(1): 133.06 +/- 39.43 wpm; MRS(2): 185.76 +/- 40.18 wpm). In posterior subcapsular cataracts, the preoperative MRS (134.1 +/- 33.72 wpm) was significantly lower than postoperatively (191.14 +/- 27.08 wpm). CONCLUSIONS: In contrast to dense nuclear cataracts and posterior subcapsular cataracts, the preoperative reading speed of patients with pure nuclear or nuclear-cortical cataracts was normal at large print sizes. The preoperative evaluation of reading acuity and speed with standardized reading tests can therefore be used to estimate the postoperative reading performance in the latter 2 types of cataract.

Aged↗

PubMed2004

Influence of uveal melanoma therapy on patients' quality of life: a psychological study.

PURPOSE: The objective of this study ws to describe the quality of life of 98 patients treated with brachytherapy or stereotactic external beam irradiation, either with the Leksell Gamma Knife or a 6-MV LINAC. METHODS: The EORTC QLQ-C30 and the EORTC QLQ-OPT37 psychological questionnaires and the HADS-D scale were used. Two visual analogue scales (VASs) were applied to compare overall quality of life before and after treatment. RESULTS: The results revealed no significant differences in quality of life (p=0.215) among treatments with different methods of radiotherapy. Comparison of quality of life before and after therapy did, however, indicate a decrease in quality of following radiotherapy. The average binocular visual acuity (VA) was 0.8 (range 0.3-1). Complication arising from the treatment included a reduction in VA in the affected eye, keratitis, cataract, scleral and corneal necrosis, radiation retinopathy, radiation optic neuropathy, retinal detachment and glaucoma. CONCLUSIONS: Due to the diagnosis revealed and the subsequent radiotherapy, patients with uveal melanoma experienced a reduced quality of life. However, compared to patients with other types of cancer, they seemed to feel relatively well and showed fewer signs of deterioration.

Adult↗

PubMed2003

Reliability of a standardized reading chart system: variance component analysis, test-retest and inter-chart reliability.

BACKGROUND: The purpose of this study was to analyze statistically the test-retest and inter-chart reliability of three standardized Radner Reading Charts with respect to reading acuity, maximum reading speed, critical print size and LogRAD/LogMAR ratio and to quantitatively identify the sources of variability. METHODS: At two testing sessions (3 to 4 weeks apart), 36 volunteers read monocularly all three Radner Reading Charts in randomized order (orthogonal Latin square design). The subjects were grouped according to their distance LogMAR visual acuity (group 1, 0.1 or better; group 2, 0.12-0.4; group 3, 0.42-0.8). Based on these 216 reading tests, crude correlations were calculated between the two testing sessions and between the three charts, and "variance component analyses" were performed for all variables. RESULTS: For all visual acuity groups and variables, the test-retest and the inter-chart reliability was high. The variance component analyses showed that the differences between individuals predominantly influenced the variance, whereas the effect of the test replication was low. The three charts caused minimal variability, indicating equality for clinical examinations. CONCLUSION: The standardized Radner Reading Charts provide clinically reliable and reproducible results for individuals with normal eyesight and for patients with visual impairment. These findings indicate that reading test systems, which consider the current international standards for visual acuity measurements (EN ISO 8596, NAS-NRC) and the psychophysical requirements for controlling optical item interactions, can provide reliable measures for clinical and scientific analyses of reading performance.

Aged↗

PubMed2002

The validity and reliability of short German sentences for measuring reading speed.

PURPOSE: To investigate whether short German sentences that have been developed to be highly comparable in number and length of words, as well as in difficulty and construction, are reliable and valid test items for measuring reading speed in order to use them for measuring simultaneously reading acuity and speed with the "Radner Reading Charts". METHODS: Tests were performed in 198 persons: 99 university students (average age 23.6+/-2.8 years) and blue-collar apprentices (average age 18.4+/-2.5 years). Reading speed and the number of errors were determined first with 24 sentences for our recently developed German reading charts (14 words equal in difficulty, length and construction) and secondly with long paragraphs of the "Zuercher Reading Test" (ZRT; paragraphs 3-5, 261 words). RESULTS: The overall mean reading speed obtained with short sentences was 209.6+/-41.0 words per minute (wpm), compared with 169.2+/-35.0 wpm for the ZRT ( P<0.001). The correlation between the short sentences and the ZRT was high ( r=0.9). Students read faster and made fewer errors than did the apprentices. Reliability analyses yielded an overall Cronbach's alpha coefficient of 0.98. The coefficient of selectivity of the 24 sentences (test items) varied from 0.75 to 0.88. CONCLUSION: The present study indicates that the 24 short single sentences we have tested are highly comparable in terms of both lexical difficulty and reading length, and it has demonstrated the validity and reliability of such sentences as test items for determining reading speed.

Adolescent↗

PubMed2002

Reading performance with a refractive multifocal and a diffractive bifocal intraocular lens.

PURPOSE: To evaluate the reading performance of a diffractive bifocal (811E, Pharmacia) and a refractive multifocal (SA40N, Allergan) intraocular lens (IOL) and compare it with that of a monofocal IOL (811C, Pharmacia) with respect to reading acuity, reading speed based on print size, maximum reading speed, reading distance, and critical print size. SETTING: Department of Ophthalmology, University of Vienna, Vienna, Austria. METHODS: This study comprised 120 pseudophakic eyes of 70 patients; each IOL group had 40 eyes. The patients' age, sex, and best corrected logMAR visual acuity were recorded. Reading acuity and speed were tested monocularly. Reading acuity was determined in logRAD (ie, the reading equivalent of logMAR). Patients with bifocal and multifocal IOLs read with best distance correction and patients with a monofocal IOL, with an addition of +3.0 diopters. RESULTS: The age, mean spherical equivalent, cylinder, and best corrected distance visual acuity were comparable among the 3 groups. The mean logRAD reading acuity was 0.17 +/- 0.18 (SD) in the 811E group (94.0% of logMAR), 0.31 +/- 0.13 in the SA40N group (73.2% of logMAR), and 0.24 +/- 0.22 in the 811C group (94.1% of logMAR). The reading acuity in the SA40N group was statistically significantly lower than in the 811E and 811C groups. The best reading distance was 30 cm in the 811E group and 40 cm in the SA40N group. The mean maximum reading speeds in words per minute were comparable: 187.5 +/- 26.1 (811E), 171.0 +/- 21.1 (SA40N), and 179.4 +/- 21.6 (811C). The reading speed, which ranged from logRAD 0.7 to 0.3, and the critical print size in the SA40N group were significantly worse than in the 811E and 811C groups. The mean critical print size in the 811E group was significantly worse than in the 811C group. CONCLUSIONS: Reading performance was acceptable in the bifocal and multifocal IOL patients, with the diffractive bifocal IOL performing best in a standardized reading test setting.

Aged↗