Michaela Velikay-Parel

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

Abstract.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 Cronbachs 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.

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

BackgroundThe 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.MethodsAt two testing sessions (3 to 4xa0weeks 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.ResultsFor 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.ConclusionThe 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.

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.

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. Conclusion: Reading performance was acceptable in the bifocal and multifocal IOL patients, with the diffractive bifocal IOL performing best in a standardized reading test setting.

The IMI Retinal Implant System

Ralf Hornig, Thomas Zehnder, Michaela Velikay-Parel, Thomas Laube, Matthias Feucht and Gisbert Richard 1IMI Intelligent Medical Implants GmbH, Bonn, Germany 2IMI Intelligent Medical Implants AG, Zug, Switzerland 3Division of Ophthalmology, University Hospital Graz 4Division of Ophthalmology, University Hospital Essen, Essen, Germany 5Division of Ophthalmology, University Medical Center Hamburg-Eppendorf, Hamburg, Germany

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 MRS1: 190.6 ± 30.74 words per minute (wpm); postoperative MRS2: 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 (MRS1: 175.77 ± 31.54 wpm; MRS2: 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 (MRS1: 133.06 ± 39.43 wpm; MRS2: 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.

Acute electrical stimulation of the human retina with an epiretinal electrode array

Purpose:u2002 To determine the threshold charges needed for eliciting visual perceptions through acute electrical stimulation of the human retina in patients suffering from retinitis pigmentosa, using an epiretinal microelectrode array.

Influence of sex, visual acuity, and systemic disease on delayed presentation for cataract surgery in Austria.

Purpose: To determine the influence of sex, age, preoperative visual acuity, and systemic disease on the delay in presentation for first‐eye cataract surgery. Setting: University Eye Clinic, Vienna, Austria. Methods: This retrospective study comprised 200 consecutive patients with age‐related cataract who were referred to the Ophthalmology Department of the University of Vienna and who had cataract surgery in the first eye. Patients with additional intraocular procedures or with other ocular comorbidity were excluded. Age, sex, preoperative best corrected Snellen visual acuity in both eyes, ocular and systemic comorbidity, and the duration of preoperative visual deterioration were recorded. The patients were divided into groups depending on systemic comorbidity. The severity of disease was categorized as no therapy necessary or nonexistent, nonsevere, or severe. Results: The mean age of women and men was 74.9 years and 70.7 years, respectively, and the mean preoperative visual acuity, 0.31 and 0.24. The duration of preoperative visual deterioration was 8.6 months and 12.2 months, respectively. All differences were statistically significant (P < .05). The visual acuity in the better eye was not significantly different between men and women. Neither the presence nor the type of systemic disease influenced preoperative visual acuity or the duration of preoperative visual deterioration. Conclusions: Although the visual acuity in the better eye was not different between men and women, men had cataract surgery after a longer duration of visual deterioration and with a worse visual acuity. More public information about cataract surgery is required to keep visual deterioration secondary to cataract to a minimum.

Development of an epiretinal prosthesis for stimulation of the human retina

Degenerations of the outer retina in retinal diseases such as retinitis pigmentosa lead to blindness due to photoreceptor loss. A therapeutic option for visual rehabilitation is presently not available. Over the last few years, a retinal prosthesis has been developed and its use has been tested in animal experiments as well as in humans. With the epiretinal implant images of the environment are taken by a camera, these data are transmitted to an intraocular encoder, and the retina is electrically stimulated by a retinal stimulator placed epiretinally. The stimulation electrodes are placed as flexible microcontact electrodes by pars plana vitrectomy in an epimacular position. The threshold is determined by stimulations of increasing amplitudes. Initial results of acute epiretinal stimulation using an epiretinal implant in legally blind patients demonstrate that acute epiretinal stimulation of the human retina is feasible and safe.ZusammenfassungDegenerationen der äußeren Retina bei Erkrankungen wie Retinitis pigmentosa können über den Verlust der Photorezeptoren zu Erblindung führen. Eine Therapieoption zur visuellen Rehabilitierung besteht derzeit nicht.In den letzten Jahren wurde eine Retinaprothese entwickelt und die Möglichkeit des Einsatzes in Tierexperimenten und auch beim Menschen getestet.Beim epiretinalen Implantat werden Bilder der Umwelt von einer Kamera aufgenommen, diese Informationen an einen intraokularen Retinaencoder weitergeleitet und über elektrische Stimulation eines epiretinal platzierten Retinastimulators die Netzhaut gereizt.Mittels Pars-plana-Vitrektomie werden die Stimulationselektroden als flexible Mikrokontaktfolien epiretinal platziert. Der Schwellwert der Stimulation wird durch Stimulationsereignisse von steigender Amplitude bestimmt. Ferner werden die visuellen Wahrnehmungen des Probanden festgehalten.Erste Ergebnisse der akuten elektrischen Stimulation mit einem epiretinalen Implantat bei (im Sinne des Gesetzes) blinden Patienten zeigen, dass eine akute epiretinale Stimulation der menschlichen Netzhaut möglich und sicher ist.AbstractDegenerations of the outer retina in retinal diseases such as retinitis pigmentosa lead to blindness due to photoreceptor loss. A therapeutic option for visual rehabilitation is presently not available.Over the last few years, a retinal prosthesis has been developed and its use has been tested in animal experiments as well as in humans.With the epiretinal implant images of the environment are taken by a camera, these data are transmitted to an intraocular encoder, and the retina is electrically stimulated by a retinal stimulator placed epiretinally.The stimulation electrodes are placed as flexible microcontact electrodes by pars plana vitrectomy in an epimacular position. The threshold is determined by stimulations of increasing amplitudes.Initial results of acute epiretinal stimulation using an epiretinal implant in legally blind patients demonstrate that acute epiretinal stimulation of the human retina is feasible and safe.

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

PurposeTo evaluate the histological changes in the retina after experimental vitreous substitution with various amounts of perfluorophenanthrene (PFPH).MethodsThirty-two rabbit eyes were mechanically vitrectomized and filled up with 0.8xa0cc or 0.2xa0cc 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.ResultsAfter 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 0.8xa0cc 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 0.2xa0cc 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 0.8xa0cc tamponade in a corresponding area.ConclusionsEven high purification of PFPH does not prevent retinal damage. The different results in different areas after vitreous substitution with 0.2xa0cc and with 0.8xa0cc demonstrate that the high specific gravity of the substance may also play a role in the development of histological changes after extended tamponade.