Harold A. Solan

Frequency of convergence insufficiency in optometry clinic settings

Purpose. To estimate the frequency of convergence insufficiency (CI) and its related characteristics among 8- to 12-year-old children randomly selected from 2 optometry clinic populations. Methods. Clinic records of 620 children were randomly selected and reviewed according to a standard protocol, using a systematic sampling method based on the total number of 8- to 12-year-old children seen over a 1-year period at 2 optometry clinics. Records were reviewed for demographic and clinical data. Data on CI-related symptoms were obtained at one of the sites. Records that met the eligibility criteria of: good visual acuity (20/30 or better in both eyes); minimal refractive error (–0.50 to +1.00 D and ≤1.00 D of astigmatism in either eye, and ≤1.00 D of anisometropia); and no strabismus were evaluated for Cl-related characteristics. Eligible children were classified according to the direction of their near heterophoria and the number of the following clinical signs present: (1) exophoria at near ≥4δ than at far; (2) insufficient fusional convergence [i.e., failing Sheards criterion or minimum normative positive fusional vergence (PFV) of 12 A base-out (BO) blur/15 A BO break]; and (3) receded nearpoint of convergence (NPC) of ≥7.5 cm break or ≥10.5 cm recovery. Children were then classified as: no Cl (nonexophoric at near or <4 δ difference between far and near); low suspect (exophoric at near and 1 sign); high suspect (exophoric at near and 2 signs); or definite Cl (exophoric at near and 3 signs). Results. Sixty-seven percent (415/620) of the records met the eligibility criteria and had complete data on phoria, NPC, and PFV. The age (mean ±SD) of the study population was 10.2 ±1.2 years. Ethnicity data were available for 85% of those eligible; the ethnic distribution was 36% African American, 29% Caucasian, 19% Hispanic, and 1% Asian. About one-half of the 415 children were classified as either low suspect (33%); high suspect (12%); or definite Cl (6%). Clinically significant Cl (high suspect and definite categories) was identified in 17.6% of the children. The percentage of children rated as symptomatic increased with the number of Cl-related clinical signs present. Conclusions. These findings suggest a high frequency of Cl in optometry clinic populations and a potential correlation between patient symptoms and the number of Cl signs present. (Optom Vis Sci 1998;75:88-96)

Effect of Attention Therapy on Reading Comprehension

This study quantified the influence of visual attention therapy on the reading comprehension of Grade 6 children with moderate reading disabilities (RD) in the absence of specific reading remediation. Thirty students with below-average reading scores were identified using standardized reading comprehension tests. Fifteen children were placed randomly in the experimental group and 15 in the control group. The Attention Battery of the Cognitive Assessment System was administered to all participants. The experimental group received 12 one-hour sessions of individually monitored, computer-based attention therapy programs; the control group received no therapy during their 12-week period. Each group was retested on attention and reading comprehension measures. In order to stimulate selective and sustained visual attention, the vision therapy stressed various aspects of arousal, activation, and vigilance. At the completion of attention therapy, the mean standard attention and reading comprehension scores of the experimental group had improved significantly. The control group, however, showed no significant improvement in reading comprehension scores after 12 weeks. Although uncertainties still exist, this investigation supports the notion that visual attention is malleable and that attention therapy has a significant effect on reading comprehension in this often neglected population.

Role of Visual Attention in Cognitive Control of Oculomotor Readiness in Students with Reading Disabilities

This study investigated eye movement and comprehension therapy in Grade 6 children with reading disabilities (RD). Both order of therapy and type of therapy were examined. Furthermore, the implications of visual attention in ameliorating reading disability are discussed. Thirty-one students with RD were identified using standardized reading comprehension tests. Eye movements were analyzed objectively using an infra-red recording device. Reading scores of participating children were 0.5 to 1 SD below the national mean. Testing took place before the start of therapy (T1) and was repeated after 12 weeks (T2) and 24 weeks (T3) of therapy. One group of students had eye movement therapy first, followed by comprehension therapy; in the other group, the order was reversed. Data were evaluated using a repeated measures MANOVA and post hoc tests. At T1, mean reading grade was 2 years below grade level, and eye movement scores were at about Grade 2 level. Mean growth in reading comprehension for the total sample was 2.6 years (p < .01) at T3; equally significant improvement was measured in eye movements (p < .01). Learning rate in reading comprehension improved from 60% (T1) to 400% (T3). Although within-group differences were statistically significant, between-group differences were not significant for comprehension or eye movements. Order of therapy (comprehension first or eye movements first) was not significant. Improvements in within-group scores for comprehension and eye movements were consistently significant at T2 and T3. Eye movement therapy improved eye movements and also resulted in significant gains in reading comprehension. Comprehension therapy likewise produced improvement both in eye movement efficiency and in reading comprehension. The results support the notion of a cognitive link among visual attention, oculomotor readiness, and reading comprehension.

Effect of luminance on visual evoked potential amplitudes in normal and disabled readers.

Background. Considerable evidence exists that some reading-disabled children have disordered visual processing, specifically in the fast processing magnocellular (M) pathway. Methods. The extent that varying luminance and temporal frequency affect amplitude and latency of visual evoked potentials (VEPs) in normally achieving and reading-disabled children grades 4 to 6 was measured. Each group consisted of approximately 30 subjects. Monocular and binocular single channel VEPs were recorded using a sinusoidal checkerboard pattern of spatial frequency 14 min arc at 3 different temporal frequencies (1, 4, and 8 Hz), and an 8 Hz flicker fusion stimulus. Stimuli were presented under high and low luminance conditions. The peak of the major positive wave component (P1Oo) of each waveform and the trough of the previous major negative wave component were identified, and the peak to trough amplitude was measured. Results. Statistical analysis of the VEP amplitudes and latencies in response to different experimental conditions was performed using a repeated measure analysis of variance (MANOVA). VEP amplitudes were significantly higher for normal readers across all conditions. Within all subjects, significant effects were found for monocular vs. binocular viewing, temporal frequencies, and high vs. low luminance. Similar analysis of latencies revealed no significant differences. Conclusions. The presence of a weaker VEP response in reading-disabled children suggests a deficit early in visual processing. The significant difference in VEP amplitudes between the two reading groups provides an objective measure of a deficit in the M pathway that has been implicated in this condition. Whether serial VEP recordings might help to assess the effects of optometric therapy by providing an independent index of therapeutic efficiency is of special interest.

Developing visual and reading efficiency in older adults.

The authors hypothesized that adults, ages 62 to 75 years, who are in good health for their age can be trained to read more efficiently using approaches similar to those reported for younger individuals. Recruited successively from the State College of Optometrys primary care clinic, the subjects were 20 volunteers who had minimum corrected Snellen visual acuity of at least 6/9 (20/30) at distance and near, no oculomotor anomalies, and no significant ocular diseases such as diabetic retinitis. After a reading efficiency pretest using the Eye-trac, an infrared eye-movement recording device, the subjects were assigned to either a control group or a reading efficiency training group. Those in the control group were tested again after the control period. All subjects were retested after experimental intervention that consisted of rapid visual processing, oculomotor, and Guided Reading training. The results revealed a statistically significant and clinically meaningful improvement in all aspects of reading efficiency, including reduced number of fixations and regressions per 100 words, increased average span of recognition, and improved reading rate without loss of comprehension, only in those who received training. Our recommendation is that training in reading efficiency should be stressed to a greater extent in reading, educational, and vision therapy programs at all age levels.

Irlen lenses do not improve accommodative accuracy at near

The purpose of the experiment was to determine the influence of Irlen lenses on steady-state accommodation in successful users, as there is speculation that near accommodative dysfunction may be a factor in these patients. Monocular steady-state accommodation in six successful Irlen patients was assessed for near blur stimuli (2, 3, and 4 D) either with nonfiltered spectacle refractive correction or their spectrally broad-band filtered spectacle refractive correction. Accommodation was measured subjectively using a Hartinger coincidence optometer. There was no significant difference in mean level of accommodation between the two conditions. Additionally, there was a small but significant increase in accommodative variability with the filtered prescription. The use of Irlen correction did not have any positive effect on monocular steady-state accommodation at near.

Dyslexia and learning disabilities: an overview.

The concept and definition of dyslexia have been evolving for more than a century. Although it is certain that dyslexia is not a unitary syndrome, a comprehensive, testable definition has eluded us. Its characteristics have been differentially related to age; maturation of the brain and nervous system; auditory, visual, and intersensory processing; genetics; nutrition; and the environment. That we are dealing with an interdisciplinary disorder is beyond question. Optometrists do not treat dyslexia. They treat reading-disabled (RD) children who manifest some type of visual dysfunction that impairs their ability to respond to the specific instruction intended to remedy the disability. The papers in this Symposium are intended to provide a more precise understanding of the role of optometrists and other members of the interdisciplinary team in the management of dyslexic children.

Eye movement problems in achieving readers: an update.

There is extant a population of subjects who have average or better than average interpretive reading skills as measured by standardized tests but who read slowly and inefficiently. Ten cases are presented where both Iowa Silent Reading Tests (ISRT) (Level III) and eye movement recordings were completed. Three of the subjects received training to improve reading efficiency. Reducing the cognitive level of the reading selections did not result in improved reading efficiency for subjects who have good interpretive skills. Substantial improvement in reading efficiency was measured in each of the three subjects selected for training.

Optometric Management of Reading Dysfunction

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Binocular Advantage and Visual Processing in Dyslexic and Control Children as Measured by Visual Evoked Potentials

The role of visual processing in dyslexia continues to stir controversy. Previous research using early components of visual evoked potentials (VEPs) has revealed differences in visual processing between dyslexics and controls. VEPs have successfully indexed binocular advantage. Intrasensory functioning could conceivably be deficient in dyslexics. This study recorded VEPs in response to contrast-reversing checkerboards binocularly and monocularly from dyslexic and control children. The overall monocular and binocular amplitudes of the major positive peaks (P100) were greater for controls than dyslexics; however, contrary to the original hypothesis, the magnitude of binocular advantage was higher for dyslexics than for the control children. Stimulus factors had an effect, but did not interact with reading ability.