VisionU

New Study on Saccadic Dysfunction in Poor Readers

A new study by Maureen Powers, David Grisham, and Philip Riles looks at reading eye movements in high school students with poor reading scores. It can be found in this month's issue of Optometry, the journal of the AOA. (You must be a member of the AOA to access this article.)

The study looked at 684 ninth grade students in five different San Jose high schools, all of whom had been identified by the school district as poor readers. The investigators used the DEM to test all subjects saccades. They found that the subjects had, on average, a ratio score of 1.54 [SD plus/minus 0.38], which is significantly worse than the average for normal reading eighth graders (1.09 [0.14], p<0.001). The number of errors committed by these students was also far worse than normal readers (4.86 [2.77] compared to 0.94 [1.47], p<0.001).

The study seems to have a solid design, although it would have been nice to see these students compared to peers who were identified as normal readers. (It would have been difficult to find those normal readers at these five high schools, however; less than 1% of students from these schools qualify academically for admission to the UC system.) Also, although Powers and Grisham's studies are typically well-constructed and help show how visual dysfunctions correlate with reading difficulties, they are the founders of a commercial enterprise (Gemstone). In the interest of full disclosure, I should note that I have worked with Powers on one study several years ago, and she never interfered with the design or results of the study.

The only reason I bring up the commercial aspect is the major difficulties in medical literature right now with big Pharma money paying for studies, or even authoring articles and getting them published under others' names. I would like to hear what you, the readers of this blog, think about this study and others done by businesses. It would seem to me that studies like this one advance the science of optometry without any real taint of self-interest, but what do you think?

David A. Damari, O.D., FCOVD, FAAO

New Research on Vision and Math Skills

Two articles just published in Optometry & Vision Development by renowned scientist/researcher, Dr. Burkhart Fischer and his colleagues strongly suggest that vision problems may affect how children acquire math skills. Both of these articles abstracts are noted below....free and full access to the complete texts of the articles can be obtained by clicking here....

Subitizing and Visual Counting in Children with Problems in Acquiring Basic Arithmetic Skills
Burkhart Fischer, Dipl. Phys., Christine Gebhardt, Dipl. Phys., and Klaus Hartnegg, Dipl. Phys.
Center of Neuroscience, Optomotor Laboratory, University of Freiburg, Freiburg, Federal Republic of Germany

ABSTRACT
The ability of recognizing a number of briefly presented items without actually counting is called subitizing (from lat. subito = suddenly). Adult subjects can subitize 3 to 4 items. For greater numbers the subjects begin a counting process relying on the visual memory of the test pattern, which needs increasingly more time as the number of items increases. The development of accuracy and speed of subitizing and visual counting was measured for subjects up to the age of 17 years. Furthermore, this study tests the hypothesis that children with difficulties in acquiring basic arithmetic skills exhibit developmental deficits in subitizing and/or counting. The study does not intend to investigate theories on the nature of dyscalculia even though most test children can be classified as dyscalculic.
Methods: Two-hundred-nineteen control subjects and 156 test subjects with problems in arithmetic skills in the age range of 7 to 17 years were given a visual counting task in which 1 to 9 items were presented for 100 ms. The subjects had to press a digit key on a numerical keyboard to indicate the number of items they had seen. Percentages of correct responses and response times were recorded.
Results: The analysis shows systematic differences between control and test children increasing with age. The percentage of test children performing below the 16-percentile of the age matched controls was estimated to be between 40% and 78% (increasing with age).
Conclusions: We concluded that the deficit in a basic visual capacity may contribute to the problems encountered by children with anomalies in acquiring basic arithmetic skills.

Effects of Daily Practice on Subitizing, Visual Counting,and Basic Arithmetic Skills
Burkhart Fischer, Dipl. Phys., Andrea Köngeter, Dipl. Biol., and Klaus Hartnegg, Dipl. Phys.
Center of Neuroscience, Optomotor Laboratory, University of Freiburg, Freiburg, Federal Republic of Germany

ABSTRACT
Background: The ability of subitizing and counting undergoes a long lasting development until
the age of 17 years. Large proportions of children with problems in acquiring basic arithmetic skills exhibit developmental deficits in the correctness and speed of this special visual capacity. The first study described in this paper tests the possibility that subitizing and visual counting can be improved by daily practice. The second study described in this paper shows that basic arithmetic skill were significantly improved in a trained as compared to an untrained
control group.
Methods: Altogether, 74 subjects (age 7 to 13 y) participated in the first study. They were given a special task for daily practice during a period of 21 days. Corresponding to the state of the subject under training the difficulty of the task was adapted. For the second study 21 children (aged 7.5 to 9 y), were recruited from a local school. All children had problems in basic mathematics and failed the test of subitizing. The training group (N=10) was given the
required training, while the waiting group (N=11) had to wait. A standard test of basic mathematics (DEMAT) was used to measure basic arithmetic skills before and after the training.
Results: The analysis of the pre-post training data revealed that subitizing and counting were significantly improved in about 85% of the subjects: they reached the normal range of the control subjects (N=133) of the same age. The second study shows that basic arithmetic skills were significantly improved in a trained as compared to an untrained control group.
Conclusion: Since the result of the second study of this paper shows a transfer from improvements in subitizing to improvements of basic arithmetic skills one may conclude that the basic visual capacity of subitizing and visual number counting contributes to the problem encountered by children with dyscalculia.

In the interest of full disclosure, it should be noted that I am the editor of Optometry & Vision Development, the official journal of the College of Optometrists in Vision Development. Dom Maino, O.D., FCOVD-A

Hyperopia and Literacy

 

Shankar S, Evans MA, Bobier WR. Hyperopia and emergent literacy of young children: Pilot study. Optom Vis Sci 2007; 84:1031-8.

 
This study looked at preschool and early-school-aged children to determine whether there were differences between hyperopic and emmetropic children in their emergent literacy skills. The study also considered related factors such as visual-motor integration which could influence performance on literacy tests. The hyperopic children ranged from 2.00-3.50 D of hyperopia along the most hyperopic meridian and the emmetropic children ranged from 0.25-1.75 D of hyperopia along the most hyperopic meridian. All the children had less than 1.00 D of astigmatism. The hyperopic children showed reduced performance on 3 of the 4 tests of emergent literacy skills (letter and word recognition, receptive vocabulary and emergent orthography. There were no differences in performance on tests of visual perception (Beery VMI and TVPS-R). The 3 literacy tests where significant differences were found involved mapping a visual stimulus to a spoken word and understanding that the visual stimulus “stands for something.”  The authors point out that the link between hyperopia and emergent literacy is quite complex, and that this correlation may not be causal. The next step in investigating this relationship would be testing hyperopic children who have been treated with spectacles. 

One of the aspects of this study that I find compelling is the fact that differences were found despite 1) a relatively small difference in hyperopia between the emmetropes and the hyperopes and 2) a relatively small amount of hyperopia in the hyperopic children. I can only imagine how much greater the differences might be if the uncorrected hyperopic children ranged from 3.00-5.00 D. I know I see these children everyday and more often than not, they are struggling in school.   

Welcome to the new research blog

Welcome to the new COVD home for posting and discussing interesting new research in optometry, neurology, education, and other fields related to the care of patients with visual needs.

For example, I just read an article on the threshold for pain in children while watching humorous videos. It seems that when a child watches a humorous video, her perception of the severity of pain does not change but her ability to tolerate that pain or some other uncomfortable situation for a longer period increases markedly. I believe many of us have used this principle when we let our patients watch videos during retinoscopy or ophthalmoscopy. Please see the full article at this site.

David Damari, O.D., FCOVD, FAAO
COVD Central Regional Director