Eccentric viewing training and its effect on the reading rates of individuals with absolute central scotomas: a meta-analysis.
Between 70 to 80% of what people with typical full vision learn comes through information gathered through vision (Li, 2004). The central part of the retina is the area through which information about details in the environment is typically acquired (Riordan-Eva & Whitcher, 2004). These details can be objects in the distance such as signs, people, and obstacles in one's path or objects more proximal such as food on a plate, faces of people in conversation, or information on the printed page. There are a number of diseases, however, that can damage the central part of the retina, leaving the affected person without vision in this area and the ability to discern detail (Bishop, 1996; Riordan-Eva & Whitcher, 2004). Before the 1960s, a popular belief was that individuals with low vision should refrain from using their vision because overuse could result in individuals using up or wearing out their vision. Subsequent research helped people understand that this was not the case (Hatlen, 2000). As a result, practitioners in the field of low vision began to investigate systematic methods to help individuals with low vision to maximize the effectiveness of the vision that they had.
Eccentric viewing is one of the strategies that has been implemented over the years to help individuals who have a loss of central vision (Cheong, Lovie-Kitchen, & Bowers, 2005; Graessley & Kirby, 1996). Eccentric viewing training helps individuals learn to move their eyes in such a way that they focus the incoming light on parts of the retina located away from the central area that has been damaged (Holcomb & Goodrich, 1976).
A number of studies have shown that this type of training can be associated with improved reading rates (Cheong et al., 2005; Crossland, Culham, Kabanarou, & Rubin, 2005; Frenesson, Jakobsson, & Nilsson, 1995; Deruaz et al., 2006). Many of these studies describe intervention protocols that include three basic steps: prescribing appropriate magnification, helping the individual identify effective eccentric viewing locations on their retina, followed by practice and often some type of follow-up support. There were, however, notable differences from study to study in the particulars of each of these steps. Methods used to identify the proper eccentric viewing location, the type of training used after the viewing location has been identified, equipment employed, and the intensity and length of support after the initial training--all varied from study to study. The overall purpose of this meta-analysis was to determine if there were differences in outcomes related to reading rate between studies and the associated particulars of the training methods employed.
Loss of vision in the foveal, or central part of the retina, can be a result of a number of pathologies (Bishop, 1996; Riordan-Eva & Whitcher, 2004), the most prevalent pathology being age-related macular degeneration (AMD) (Retina International, 2010). This condition affects 1.75 million people in the United States alone, 1.47% of the population over 40 and 15% of women over 80 (National Eye Institute, 2010). For younger individuals, Stargardt's disease, Best's disease, diabetic retinopothy, and optic nerve atrophy can also result in central scotomas (Nilsson, 1989). Stargardt's disease is hereditary, affects 1 in 8,000 to 10,000 individuals, and often first begins to manifest itself in childhood. The significant impact it has on vision usually does not occur until an individual is in their 40s (Altaweel, 2010). Best's disease, or vitelliform macular dystrophy, is an eye condition that usually begins to appear as a lesion in the macula during childhood (Altaweel, 2010). Diabetic retinopathy is damage to the retina due to diabetes. When these conditions result in the loss of the central field of vision, they can have significant impact on an individual's ability to conduct many common activities such as preparing food, foot travel, driving, recognizing faces, watching TV, and reading (Bullimore, Bailey, & Wacker, 1991; Vukicevic & Fitzmaurice, 2005a; 2005b; 2009). Optic nerve atrophy is caused by damage to the optic nerve (Blind Babies Foundation, 1999).
If the ability to perceive detail through the central field is lost, however, individuals can be trained to use another part of the retina to take over the task of acquiring detailed visual information (Goodrich, 1986). The use of this alternate area of the retina is called eccentric viewing (Holcomb & Goodrich, 1976). Because the density of receptor cells that detect detail decreases farther away from the fovea, eccentric viewing is often combined with magnification and illumination to achieve increased functionality (Fuller & Schmiedecke, 2006; Goodrich, 1986).
Both accuracy of word and letter recognition (Deruaz et al., 2006; Holcomb & Goodrich, 1976; Nilsson & Nilsson, 1986; Nilsson, 1990; Nilsson, Frennesson, & Nilsson, 2003), and reading rate (Cheong et al., 2005; Crossland et al., 2005; Frennesson et al., 1995; Gustafsson & Inde, 2004; Logan, 2005; Palmer, Logan, Dutton, & Nabili, 2009; Nilsson, 1990; Nilsson et al., 2003) have been shown to increase significantly after a program of both eccentric viewing training and optimization of optical devices has been implemented. In addition, other important skills have been restored for people who have had eccentric viewing training, including skills related to employment (Nilsson et al., 2003) and skills related to the activities of daily living such as cooking, traveling on foot, and watching television (Vukicevic & Fitzmaurice, 2005a; 2005b; 2009).
Although training in the area of eccentric viewing is common, widespread, and considered standard practice, a great deal of variation exists in the procedures for evaluation, time spent in training, and the techniques used for both evaluation and training (Stelmack, Massof, & Stelmack, 2004). An important first step in the rehabilitation process to build skill in eccentric viewing is helping the individual identify the most useful part of the retina on which to aim the incoming light and image. Because scotomas have a wide variety of shapes and sizes (Sunness, Applegate, Haselwood, & Rubin, 1996), the selection of the best location may differ greatly from one individual to another. The accurate selection of the most appropriate location may be complicated by the fact that one area of the retina may provide a better image but focusing on the image in that area may be more difficult for the individual to sustain for extended viewing periods (Altpeter, Mackeben, & Trauzettel-Klosinski, 2000).
Often, individuals can identify a preferred retinal location on their own (Cummings, Whittaker, Watson, & Budd, 1985), and results have been mixed from formal studies that have tried to find a single area of the retina that can provide the most functionality for everyone. Fletcher and Schuchard (1997) suggested that individuals prefer not to use areas on the retina above or to the right of the scotoma. In a subsequent study, however, Fletcher, Schuchard, and Watson (1999) found that for participants who had no training, 33% of variance in reading rate was due to scotoma location relative to their chosen preferred reading location, and 42% was due to visual acuity. Watson, Schuchard, De l'Aune, and Watkins (2006) found that individuals who used a preferred retinal location to the left of or above their scotoma had more difficulty navigating through text. Timberlake, Peli, Essock, and Augliere (1987) found increased reading speeds for individuals who focused below left or above fight of the scotoma.
Similarly, Messias et al. (2007) showed that individuals with Stargardt's disease often choose an area below the scotoma. Sunness et al. (1996), however, found that for patients with geographic atrophy, 65% placed
the scotoma to the right of their preferred location, 15% to the left, and 22% above the preferred fixation area. Those with Stargardt's disease tended to place the scotoma far above the fixation site. Reading rates were also found to be faster when the scotoma was above the fixation area and slower when the scotoma was to the left.
Further complicating matters, multiple studies have found evidence that individuals may commonly use multiple locations on the retina at different times when viewing something, and that this skill has been associated with improved perception (Duret, Issenhuth, & Safran, 1999; Deruaz et al., 2004; Messias et al., 2007; Goldschmidt, Deruaz, Lorincz, & Whatham, 2010; Raasch, 2004). In fact, the use of multiple locations has been found to be more likely in individuals who have larger scotomas (Whittaker, 1988). It has been hypothesized that the use of multiple locations may be to compensate for Troxler's phenomenon, or the natural fading of image clarity as viewing time increases (Raasch, 2004; Duret et al., 1999). High resolution is not always required for every task, and patients with Stargardt's disease were found to vary the location they use on the retina depending on the task being performed and the distance from which important information was being viewed (Sullivan, Jovancevic, Hayhoe, & Sterns, 2005). For participants with visual acuities between 20/80 and 20/200, Sunness et al. (1996) also found that their reading rate was not associated with visual acuity in the eccentric viewing area or with the age of the patient, but was associated with the size of the scotoma. Some researchers have studied different training protocols to identify ones that might be most effective. Some differences between techniques were found but participants in these studies were individuals with normal vision where scotomas were simulated (Fornos, Sommerhalder, Rappaz, Pelizzone, & Safran, 2006; Yu, Cheung, Legge, & Chung, 2010; Yu, 2010). Some studies were designed to evaluate the effectiveness of particular eccentric viewing training software such as EccVue software (Fitzmaurice & Clarke, 2000; Vukicevic & Fitzmaurice, 2005a; 2005b) and Movitext (Gustafsson & Inde, 2004). Other studies were designed to evaluate the effectiveness of biofeedback (Vingolo, Salvatore, & Cavarretta, 2009), ocular-motor training (Seiple, Grant, & Szlyk, 2011), sensomotoric training (Nhung, Nguyen, Stockum, Hahn, & Trauzettel-Klosinski, 2011; Seiple, Szlyk, McMahon, Pulido, & Fishman, 2005), and reading practice (Palmer et al., 2009; Seiple et al., 2011). There has been evidence that training to access information that has certain visual characteristics does not necessarily transfer to objects with other illumination characteristics (Chung, Levi, & Li, 2006), so that the transfer of skills learned in one context may not necessarily transfer to another--especially with electronically generated visual targets.
In addition, more extensive training may not necessarily bring additional benefits. A study by Zeevi, Peli, and Stark (1979) suggested that eccentric fixation within the near periphery, plus or minus 8 degrees, can be achieved within a short period of time (10-40 seconds), even in individuals who are new to the task. Furthermore, effects may fade without sustained practice (Deruaz et al., 2006). Yet, as individuals gain experience, their ability to immediately fixate eccentrically improves, as demonstrated by smoother eye movements to achieve effective eye positioning (Zeevi et al., 1979).
The purpose of this study was to conduct a meta-analysis of the data generated and presented from published studies in which researchers have detailed training protocols, and to find if any particular intervention protocol or particular factors, such as participant age and acuity, were associated with significantly different outcomes in terms of reading speed.
Identification of key words
The initial key words for this project were provided by the American Printing House for the Blind (APH): visual efficiency, visual plasticity, functional visual development, visual skills, visual utilization, Barraga, program to develop functional visual efficiency (PDFVE), Randy Jose, Anne Corn, sensory processing, visual efficiency, low vision, low vision training, low vision skill development, visual perceptual skills, object skills recognition, visual discrimination, visual recognition, visual identification, visual spatial relationship, visual memory, figure ground relationship, visual skills acquisition, visual closure, learning to see and visual training. Additional key words were added as the search progressed and reviewers provided feedback: peripheral vision, eccentric viewing, video training, central scotoma, macular degeneration, AMD, Stargardt's disease, vision rehabilitation, eccentric fixation, and preferred retinal locus (PRL).
Collection of literature
An initial computer-based search using the University of Arizona Central Search through Social Science and Life and Health Sciences data bases was undertaken. Similar, more focused searches using the initial results from the central search were conducted using PubMed, ERIC, and Web of Knowledge, and reviewing articles identified by an "articles cited by" link when available. A similar search was conducted using Google Scholar as well.
Sorting the literature
The abstracts of the articles, obtained through the process outlined above, were reviewed and those articles that related to eccentric viewing training were sorted into a separate list. Copies of relevant articles were obtained and their lists of references reviewed for relevant articles not yet identified. Those articles that were relevant were collected and their lists of references were reviewed for additional articles. The newly identified articles were then obtained and their references were reviewed. This process was repeated until no new and relevant articles were identified.
The collected articles were then more closely reviewed to determine if they had been published and peer reviewed, if the participants in the studies were identified as individuals with visual impairment, and if they reported on research-related interventions associated with improving eccentric viewing skills and reading rate for individuals.
DATA EXTRACTION AND ANALYSIS
Dependent or outcome variables. Reading rate: All measures for reading rates given in the studies were converted to words per minute. Percent change in reading rate and final reading rate in words per minute were used as outcome variables. Effect sizes were determined by calculating the appropriate Cohen's d for each study. The significance in the differences between pre- and post-treatment results (or control and treatment results) was reported based on information provided in the individual studies. In those cases where significance was not reported, significance was calculated based on data provided in that study, if possible.
Independent variables and factors. The independent variables used in this analysis were overall treatment hours and treatment duration. Age of participants and visual acuity were incorporated as additional factors.
Bivariate correlation was used to determine if there were simple correlations among the following variables: final reading rate in words per minute, change in reading speed (percentage and words per minute), effect size (Cohen's d), length of training period, amount of training, average age of participants in each study, and average visual acuity of participants in each study. An independent samples t test was used to determine if there were significant differences between the final reading rates reported in the different studies. Although conducting a one-way analysis of variance, ANOVA and F-test would normally be appropriate for this type of analysis in order to reduce the chance of a false rejection of a true null hypothesis (type 1 error), in this instance only summary data was available. If individual data points were available for each study, an ANOVA could have been run instead of multiple t tests. Regression analysis was conducted to determine if a predictive model could be developed for final reading rate or improvement in reading rate-based number of training hours, with age of participants and visual acuity of participants included as additional factors.
Microsoft Excel software was used to calculate means and standard deviations from data extracted from individual studies (see Table 1) and to calculate values of the t statistic for comparisons between studies (see Table 2). Results for correlations were considered significant at p < 0.05. For the multiple t tests, individual results were considered significant at p < 0.0007 in order to reduce the probability of a false positive to 0.05 using a Bernoulli correction (Glantz, 2002). SPSS software was used to conduct the correlation analysis (Table 3) and regression analysis.
Fifty-three articles were found to be related directly to the development of eccentric viewing skills. Of these, eight were eliminated because they described the biological and optical foundations of eccentric viewing. Eighteen more were eliminated because they did not describe a treatment; six were eliminated because they were articles that did not have individuals with visual impairments as subjects, but simulated visual impairment through some form of occlusion. Of the remaining articles, four were not available in English and nine did not describe outcomes related to reading or included information on reading accuracy and comprehension but not reading rates. After review, the term preferred retinal locus was added to the search, using the same criteria, and additional articles were located. This left sixteen articles that contained information on training protocols and effects on the reading rate of participants. Summaries of these articles and the relevant data they included are contained in Table 1.
Almost all eccentric viewing training methodologies were found to be associated with comparable final reading speeds, but no significant differences in final reading speed were found between eccentric viewing training methodologies with comparably aged participants (see Table 2). There were significant differences, however, between the comparable age groups that were not provided with eccentric viewing training (see Nilsson, 1990) and those that were provided with eccentric viewing training. Studies in which there were younger participants and no training (see Crossland et al., 2005; Crossland, Culham, & Rubin, 2004) achieved results similar to those studies with older participants with training. The study with younger participants and training (Nhung et al., 2011) generally showed the highest final reading speeds. The negative relationship between age and final reading speed was further confirmed through correlation analysis, shown in Table 3. A correlation was also found between visual acuity and the percent change in reading speed.
Regression models were built using different combinations of three independent variables: age, acuity, and treatement hours (for example, age, acuity, and treatment hours; age and treatment hours; acuity and treatment hours; and age and acuity). In these models, age, acuity, and treatment hours were not found to predictive of Cohen's d, or change in reading rate. Using the data from these studies, regression models built using combinations of age, acuity, and treatment hours were not significantly predictive of Cohen's d, or the change in reading rate. The final reading rate, however, could be predicted with age and number of training hours using linear regression (p = 0.002). Number of training hours was positively predictive (beta = 0.386, p = 0.046) and age was negatively predictive (beta = -0.671, p = 0.002). This suggested that the more hours spent in training, the faster the final reading speed would be for trainees; however, the older the trainees were, the lower the final reading rate was.
Detailed information on the comparisons and correlations were provided despite the lack of significant differences found, because potential trends could be identified and the lack of significance may have been more a function of the small data set rather than a lack of actual association. Further studies that use greater sample sizes might resolve some of the differences suggested by the comparisons and correlations found here.
This analysis provided no statistical basis to determine if one of the treatment protocols described in these studies was more effective in improving reading rate than another, and there was quite a bit of variability in the protocols described. For example: (1) two studies described an intervention that did not include training (Crossland et al., 2005; Nilsson, 1990), and another had up to nine weeks of training (Gustafsson & Inde, 2004); (2) one intervention involved simply describing what eccentric viewing was to the participants (Crossland et al., 2005), and others followed up with training some with formal practice (Frennesson et al., 1995; Nilsson, 1990; Nilsson et al., 2003; Palmer et al., 2009); or training with self-guided practice (Cheong et al., 2005); (3) still other studies described using high technology training systems with computer software (Gustafsson & Inde, 2004) and displays (Nilsson et al., 1998), and (4) finally, another had intensive initial instruction with subsequent coaching by a vision specialist (Frennesson et al., 1995). In addition, other groups of researchers employed biofeedback (Vingolo et al., 2009) or sensomotoric training (Nhung et al., 2011). The fact that no difference was found between any of the protocols except in one case (Nilsson, 1990) where there was no treatment may suggest a certain flexibility in the learning process or alternately an upper limit on reading speed using eccentric viewing. Indeed, Crossland et al. (2005) described a minimal intervention and the results were not significantly different from the intervention studies but were significantly different from the nonintervention group in Nilsson (1990).
Although many of the correlations were not found to be significant, the strength of the correlations is suggestive and offers guidance for further investigation. For example, final reading rate may be negatively correlated with age. Because the participants in these studies tended to be older, there may be an upper limit on reading speed related to age. In fact, Crossland et al. (2004; 2005) showed that younger participants adapted to and learned eccentric viewing techniques more quickly than older participants did.
Data on the effect of training on final reading rate was mixed. In the regression model, more training was predictive of higher final reading rate and yet the correlation was not strong in the bivariate correlation analysis. The regression analysis accounted for the confounding factor of age and may strengthen the case for longer training periods. At the same time, Gustafsson and Inde's (2004) findings suggested that individuals may be able to identify an effective eccentric viewing location without assistance and then selftrain. Additionally, individuals tended to adjust and change their preferred viewing location spontaneously (Duret et al., 1999; Deruaz et al., 2004; Messias et al., 2007; Goldschmidt et al., 2010; Raasch, 2004). It may be that interventions in which methods are prescribed by a trainer are interfering with the natural monitoring and adjusting process of the trainees. Training that is less prescriptive and more collaborative might be more effective.
Further research could be conducted that establishes the relative importance of various components of eccentric viewing intervention on reading outcomes. For example, understanding the relative importance of magnification, identification of a preferred viewing locus, and training could help guide intervention protocols. Because outcomes between the various treatment protocols were not significantly different, evidence from this analysis may suggest that perhaps prescribing proper magnification is associated with the most significant contribution to improved outcomes.
The implications for practice are simply that eccentric viewing is an effective way for individuals with central scotomas to improve the use of the vision that they have. Because there did not appear to be one process for training that was associated with higher final reading rates, there is evidence that a wide range of training protocols would be effective, and that the personal preferences of the instructor and consumer should be given significant consideration during program planning.
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Jon Howe, M.A., doctoral candidate, Department of Disability and Psychoeducational Studies, College of Education. University of Arizona, 1430 East Second Street, P.O. Box 210069, Tucson, AZ 85721; e-mail: <firstname.lastname@example.org>.
Table 1 Summary of Studies Used in Meta-Analysis. Acuity mean Study # Age mean (std) Condition logMAR Cheong et 25 80.3 AMD .628# al., 2005 Crossland 25 16 Various Not given et al., ACS 2005 Crossland, 18 Not given AMD Not given et al., JMD 2004 Frennesson 10 80.1 (+/-5.6 years) AMD 1.46# et al., ACS 1995 Gustafsson 9 45.8 ACS 1.1-1.54# & Inde, 2004 Logan, 20 70 ACS Not given 2005 Nilsson et 18 77.4 AMD 1.398# al., 2003 Nilsson et 6 71 AMD 1.22# al., 1998 Nilsson, 20 76.8 AMD 1.1# 1990 Nilsson, 20 77.0 AMD 1.1# 1990 Nilsson R 120 72 (9.9) SMD .957# Nilsson, DMD 1986 HMD Seiple et 16 77 AMD .75 al., 2005 Nhung et 20 30 Juv. Mac 1.0 al., 2011 dystr 16 31 1.0# Palmer et 242 75.4 AMD Not given al., 2009 Seiple et 30 79 AMD .823# al., 2011 30 79 AMD .823# 30 79 AMD .823# 6 78.4 AMD .900 Vingolo et 5 53.8 Var. w .546 al., 2009 ACS Watson et 7 75.7 .91 al., 2006 Length of Study Intervention Design interv Cheong et In office prac In Pre/post With In office al., office+ Control 2 week 2005 at home In training office + home+ frame Crossland None Pre/post < 1yr et al., Self-discovery 2005 of PRL and Monitor Crossland, No training Pre/post 12 mo. et al., 2004 Frennesson 1/2 hr on training Pre/post Not given et al., program and 1995 1 hr. work with vision spec. Gustafsson MoviText Pre/post 6 to 9 & Inde, method weeks 2004 3--1hr sessions Logan, Determination Pre/post Ave 6.5 2005 of PRL Mixed hrs Optimal method refraction Train (6.5 hr sessions) Independent practice Nilsson et Determination Pre/post Not given al., 2003 of PRL Refraction Train (5.2 hr sessions) Independent practice Nilsson et Computer video Pre/post 4 weeks al., 1998 display training in TRL Nilsson, Optical Aids Pre/post 4 weeks 1990 Instruction in approx use of aids Eccentric viewing training Nilsson, Optical Aids Pre/post 1990 Instruction in use of aids Nilsson R Weekly Pre/post variable Nilsson, rehabilitation 1986 sessions as needed Seiple et Eye-movement Pre/post 8 weeks al., 2005 training Nhung et Rapid serial Pre/post 4 weeks al., 2011 visual presentation sensomotoric training Pre/post 4 weeks Palmer et Determination Pre/Post Retro Retrospective al., 2009 of PRL Analysis Optimal Paired t refraction Optimal lighting Train (3-4 1hr sessions) Supervised practice Seiple et Visual Random 6 weeks al., 2011 awareness repeat, and eccentric measure, viewing counter balance, crossover Reading eye 6 weeks movement Reading 6 weeks practice Control (no 18 weeks training) Vingolo et MP-1 Pre/post 10 weeks al., 2009 Biofeedback examination Watson et Trained to use Pre/post n/a al., 2006 reinal locus below scotoma Ave # of 1 hr. WPM B: Before % Study sessions A: After change Cheong et Not given B: 66.00 (12.16) 19.2% al., A: 78.67 2005 (10.263)# Crossland 5 B: 58(33) 53.4%# et al., A: 89 (35) 2005 Crossland, n/a B: 85 (37) A:73 -14.1 et al., (38) 2004 Frennesson 2.6 (+/-0.69) B: 11.5 (4.5) 412%# et al., A: 58.9 (19.7) 1995 Gustafsson 3 B: 45.4 (37.87) 57.2% & Inde, A: 80.4 (41.65)# 2004 Logan, 5 B: 44.1 A: 68.7 24.6%# 2005 Nilsson et 5.2 B: 9.0 (5.8) 659% al., 2003 A: 68.3 (19.4) Nilsson et 4 Inns median B: 0 -12 -- al., 1998 A: (71) 62-76 Nilsson, 4.8(1.0) B: 0 n/a 1990 A: 75.5 (31.1) Nilsson, 0 B: 0 n/a 1990 A: 22.6 (22.2) Nilsson R Not reported B: 0 n/a Nilsson, A: 84.3 (43.9) 1986 Seiple et Not reported B: 91 27.1% al., 2005 A: 115.7 Nhung et 20 1/2 hr B: 83 (23) 25.3% al., 2011 A: 104 (31.9) B: 102 (46.7)# 20 1/2 hr A: 122 (25.9)# 19.6% Palmer et 3.8 (1.6) B: 48 (35) A: 71.9 49.8%# al., 2009 (30.5) Seiple et 2hr/wk B: 64.8 (36.5) A: -13% al., 2011 56.4 2hr/wk B: 64.8 (36.5) 42.1% A: 92.1# 2hr/wk B: 64.8 (36.5) -15% A: 55.2# n/a Not given Not given Vingolo et 20 min/wk B: 64.3 (68) 42.7% al., 2009 A: 91.8 (86.3) Watson et 15 im total B: 7.4 A: 34.1 -54.1% al., 2006 Significance WPM (Stat. Effect size(r) Study change method) (Cohen's d) Cheong et 12.67 Pre/post 0.9208 (4.722) al., P=0.02 2005 (unpaired) Crossland 31 <0.05 0.4146 (0.9114) et al., (ANOVA) 2005 Crossland, -12 Not reported -.1580 (-.3200) et al., 2004 Frennesson 47.4 <0.001 (not et al., given) 1995 Gustafsson 35 <0.005 0.7181 (2.0635) & Inde, (Paired t) 2004 Logan, 24.6 Not given Insufficient 2005 information Nilsson et 59.3 <0.001 (not 0.9005 (4.1417) al., 2003 given) Nilsson et Insuff na Insufficient al., 1998 inform information Nilsson, 75.5 < 0.001 Insufficient 1990 information Nilsson, 22.6 Insufficient Insufficient 1990 information information Nilsson R 84.3 Not reported Insufficient Nilsson, information 1986 Seiple et 24.7 p = 0.001 Insufficient al., 2005 Wilcoxon information rank sum Nhung et 21 p = 0.01 .3532 (.7551) al., 2011 (paired-t) p = 0.006 20 (paired-t) .2560 (.5297) Palmer et 23.9 < 0.001 (not 0.3421 (0.7281) al., 2009 given) Seiple et -8.4 (7.2) Ns Insufficient al., 2011 information 27.3 (6.8) p = 0.0002 Insufficient (t test) information -9.6 (7.2) Ns Insufficient information .96 (1.3) ns Insufficient information Vingolo et 27.5 P = 0.04 .1743 (.3540) al., 2009 (paired-t) Watson et -40.3 Not reported Insufficient al., 2006 information Note: ACS = absolute central scotoma, PRL = Preferred reading location, AMD = Adult macular degeneration, DR = Diabetic retinopothy, Gl Glau coma, OA = Optic Atrophy, M = Myopia, EVT = eccentric viewing training. JMD = Junior Macular Degeneration. Italicized numbers calculated for this study from data provided in articles. Effect size calculator: http://www.uccs.edu/~faculty/lbecker/ Cohen's d (Gravetter & Wallnau 2005.). Cohen's d for t/test repeated measures (non/paired) = (mean difference/std deviation) and effect size r=[[([t.sup.2]/ ([t.sup.2]+df)].sup.1/2]. Small effect: 0 < d < 0.2, medium effect 0.2 < d < 0.8, large effect 0.8 < d < 1.0. Note: Numbers calculated for this study from data provided in articles were indicated with #. Table 2 Comparison of final reading rate between studies. Cheong Crossland Crossland et al. et al. et al. Frennesson (2005) (2005) (2004) et al. (1995) Cheong et al. (2005) -- Crossland (2005) -0.5010 Crossland et al. (2004) 0.2519 1.4269 Frennesson et al. (1995) 1.6368 2.5481 1.0886 Gustafsson & Inde (2004) -0.0707 0.5988 -0.4648 -1.4666 Palmer et al. (2009) 0.3819 2.6313 0.1450 -1.3349 Nilsson et al. (2003) 0.8916 2.2662 0.4674 -1.2219 Nilsson (1990) 0.2421 1.4318 -0.1037 -1.4010 Nilsson (1990) 4.2289` 7.0764 * 4.8587 * 4.3073 * Nilsson et al. (1998) -0.2211 0.5026 -1.0347 -1.8094 Nhung et al. (2011) -1.3410 -1.4852 -2.7329 -4.0783 Nhung et al. (2011) -2.8016 -3.2404 -4.3364 * -6.5866 * Vingalo et al. (2009) -0.2543 -0.1243 -0.7311 -1.1871 Palmer Gustafsson et al. Nilsson et Nilsson et al. (2004) (2009) al. (2003) (1990) Cheong et al. (2005) Crossland (2005) Crossland et al. (2004) Frennesson et al. (1995) Gustafsson & Inde (2004) Palmer et al. (2009) 0.5641 Nilsson et al. (2003) 0.7989 0.4929 Nilsson (1990) 0.3358 -0.3083 -0.6829 Nilsson (1990) 3.6330 * 6.7211 * 6.5765 * 8.0861 * Nilsson et al. (1998) -0.1788 -3.1291 -1.5204 -2.5975 Nhung et al. (2011) -1.2698 -4.5081 * -4.1099 * -4.2231 * Nhung et al. (2011) -2.3888 -6.4161 * -6.8911 * -6.6342 * Vingalo et al. (2009) -0.2937 -1.3680 -1.1198 -0.8387 Nilsson Nhung Nilsson et al. Nhung et et al. (1990) (1998) al. (2011) (2011) Cheong et al. (2005) Crossland (2005) Crossland et al. (2004) Frennesson et al. (1995) Gustafsson & Inde (2004) Palmer et al. (2009) Nilsson et al. (2003) Nilsson (1990) Nilsson (1990) Nilsson et al. (1998) -5.8387 Nhung et al. (2011) -9.0301 * -1.9215 Nhung et al. (2011) -12.0513 * -3.3513 -1.8251 Vingalo et al. (2009) -3.2108 -0.3580 0.5280 1.2870 Significant p < 0.0007. Note: Only studies that provided standard deviations for their reported final reading rate were included in this analysis. Table 3 Bivariate Pearson correlations between variables. Age Acuity WPM change Cohen's d Acuity .073 WPM change -.015 .422 Cohen's d .671 .216 .474 Sessions -.215 -.252 .003 -.229 WPM final -.573 * -.279 .274 -.392 Percent change .221 .808 ** .688 ** .563 Sessions WPM final Acuity WPM change Cohen's d Sessions WPM final .479 Percent change -.229 -.140 * Significant p < 0.05. ** Significant p < .001.
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|Title Annotation:||CEU Article|
|Publication:||Journal of Visual Impairment & Blindness|
|Article Type:||Clinical report|
|Date:||Sep 1, 2012|
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