Kyle Arnoldi

Joint statement - Learning disabilities, dyslexia, and vision

Learning disabilities, including reading disabilities, are commonly diagnosed in children. Their etiologies are multifactorial, reflecting genetic influences and dysfunction of brain systems. Learning disabilities are complex problems that require complex solutions. Early recognition and referral to qualified educational professionals for evidence-based evaluations and treatments seem necessary to achieve the best possible outcome. Most experts believe that dyslexia is a language-based disorder. Vision problems can interfere with the process of learning; however, vision problems are not the cause of primary dyslexia or learning disabilities. Scientific evidence does not support the efficacy of eye exercises, behavioral vision therapy, or special tinted filters or lenses for improving the long-term educational performance in these complex pediatric neurocognitive conditions. Diagnostic and treatment approaches that lack scientific evidence of efficacy, including eye exercises, behavioral vision therapy, or special tinted filters or lenses, are not endorsed and should not be recommended.

Surgery for esotropia with a high accommodative convergence/accommodation ratio: effects on accommodative vergence and binocularity.

BACKGROUND AND OBJECTIVE To determine the effectiveness of strabismus surgery as an alternative treatment for high accommodative convergence/accommodation (AC/A) ratio (nonrefractive accommodative) esotropia. PATIENTS AND METHODS Twenty-three consecutive children with an AC/A ratio of 5:1 or greater and a distance-near disparity of 10 prism diopters (PD) or more were studied in a prospective design. Each patient was treated by recession of both medial rectus muscles for the full amount of esotropia measured at near fixation through the full distance hyperopic correction. The magnitude of eso deviation, the AC/A ratio, and the grade of binocularity were measured before and a minimum of 4 months after strabismus surgery. RESULTS Surgery reduced the mean preoperative eso deviation at near fixation by a factor of 4 (from a mean of 37 PD to a mean of 9 PD). Surgery eliminated the need for bifocals in 96 percent of the patients. The grade of binocular fusion or stereopsis improved in 70 percent of the patients, remained unchanged in 26 percent, and was degraded in 4 percent. Three (13 percent) of the children became exophoric; none of the children were exotropic. CONCLUSION These results demonstrate that strabismus surgery is an effective alternative to the long-term use of bifocals in the treatment of high AC/A ratio esotropia. Surgery may be more effective than bifocals in restoring normal stereopsis and binocular fusion.

Prevalence of Intracranial Lesions in Children Initially Diagnosed With Disconjugate Nystagmus (Spasmus Nutans)

A small number of children who develop disconjugate nystagmus, torticollis, and head titubation (spasmus nutans) have been found to have optic chiasm or third ventricle gliomas. However, the prevalence of glioma or other developmental abnormalities in this disorder is unknown because no large series of spasmus nutans cases has previously been reported. A reviewer of the records of 67 consecutive children initially diagnosed with spasmus nutans and followed for an average of 3.3 years at the St Louis Childrens Hospital revealed the following: 61% had a history of prematurity, developmental delay, or other systemic abnormality; strabismus, most commonly infantile esotropia, developed in 55%; 43% had neuroimaging studies; and 0% had evidence of a glioma or showed signs of tumor on follow-up examinations. From this consecutive patient series, we estimate the prevalence of tumor in spasmus nutans to be less than 1.4%. Without other evidence of an intracranial mass lesion, neuroimaging of infants initially diagnosed with spasmus nutans may not be immediately warranted.

Lateral incomitance in exotropia: Fact or artifact?

The prevalence of significant lateral incomitance in patients with nonparetic exotropia is reported to be 22%. We speculated that measurement artifact may be the cause for some cases of apparent lateral incomitance. We measured the effective power of plastic ophthalmic prisms using a helium-neon laser in the frontal plane position and at 10 degrees, 20 degrees, and 30 degrees of rotation from the frontal plane. The rotated prisms represented the situation in which a neutralizing prism rotates with the head during measurement of lateral gaze positions. For prisms of 35 prism diopters or more, even 10 degrees of rotation produced significant artifactual incomitance. For smaller prisms, 20 degrees or more of rotation was necessary to induce significant lateral incomitance. We prospectively measured 40 consecutive patients with exotropia. Only three patients (9%) had true incomitance greater than 5 delta, and only one had incomitance in both directions of gaze. Significant lateral incomitance could be induced in every patient examined by improperly positioning the neutralizing prism. Because the detection of lateral incomitance causes most strabismus surgeons to reduce the amount of surgery they perform, special care is necessary when measuring deviations in lateral gazes.

A Review of Convergence Insufficiency: What Are We Really Accomplishing with Exercises?

Introduction Orthoptic exercises have been the primary treatment for convergence insufficiency since this conditions first description in 1855. It is presumed that exercises work by improving fusional convergence. In recent years, research from eye movement laboratories has challenged our theories on the nature and dynamics of convergence, the effect of convergence exercises, and the etiology of primary convergence insufficiency. Methods A review of the ophthalmological, optometric, and basic science literature was done to retrieve the most recent research on vergence eye movements and convergence insufficiency. Results Convergence appears to be a bi-phasic response to a change in stimulus position in depth. The first phase, which may represent the contribution of proximal convergence, is not under visual feedback, is fast with a short latency, and is triggered by stimuli moving rapidly in depth or by large, sudden changes in fixation. This phase is followed by a slow vergence movement with a slightly longer latency, triggered by small disparity vergence errors. The second phase is under the control of visual feedback, and represents the contributions of fusional and accommodative convergence. Eye movement recordings indicate that the velocity and amplitude of the first phase of convergence are temporarily adaptable with exercises. The second phase does not appear to be amenable to training. Tonic convergence is also trainable. Conclusion Convergence exercises are effective in temporarily improving the dynamics of proximal and tonic convergence, but have little effect on fusional or accommodative convergence.

The Gradient AC/A Ratio: What's Really Normal?

The two most commonly used methods for determining the AC/A ratio are the Gradient Method and the Clinical Method. Though both methods are simple, practical, and often used interchangeably, they are really quite different. The Gradient AC/A measures the amount of convergence generated by a diopter of accommodative effort, while the Clinical Method detects the presence of a distance-near disparity of 10 or more prism diopters of esotropia. The purpose of this prospective study was to compare the Gradient and Clinical AC/A in 69 consecutive patients presenting with acquired nonparalytic esotropia. In addition, two methods of calculating the Gradient AC/A were compared: “minus” AC/A in which accommodation (and therefore accommodative convergence) is stimulated, and “plus” AC/A in which accommodation (and accommodative convergence) is relaxed. Mean Gradient AC/A for patients with a normal Clinical AC/A was 2:1, below the range traditionally thought of as normal. Mean Gradient AC/A for patients with a high Clinical AC/A was 5:1. Forty-four percent of those with a high Clinical AC/A had a normal or low Gradient AC/A, suggestive of nonaccommodative convergence excess. Mean Gradient AC/A with plus lenses was statistically identical to the AC/A with the minus lens method.

Long-Term Surgical Outcome of Partially Accommodative Esotropia

Partially accommodative esotropia is an acquired strabismus characterized by high hyperopia, a normal AC/A ratio, and a deviation that responds only partially to spectacle correction. Surgery is done for the non-accommodative portion of the deviation. Over-corrections are managed by reducing the hyperopic power of the spectacles. This retrospective study was done to determine the risk factors for a poor surgical outcome, and to evaluate the efficacy of hyperopic spectacle reduction in the long-term management of consecutive exotropia. Of the 108 patients enrolled, 19% had a residual esotropia, 37% were surgical successes, and 44% developed consecutive exotropia. Residual ET was associated with deteriorated refractive esotropia, moderate to severe amblyopia, and increasing hyperopia with age. Consecutive XT was associated with a distance-near disparity, low hyperopic refractive error, anisometropia, poor binocular vision, and undercorrection of the hyperopic refractive error prior to surgery. Intentional reduction of the hyperopic correction was not successful in the long-term management of consecutive XT. Fifty-eight percent of those managed in this manner developed a pseudo-dissociated horizontal deviation. The high rate of consecutive exotropia following standard surgery suggests that augmented surgery for partially accommodative esotropia is highly likely to result in overcorrection.

Cerebral Palsy for the Pediatric Eye Care Team Part II: Diagnosis and Treatment of Ocular Motor Deficits.

Introduction Cerebral palsy is a term used to describe a spectrum of neurological deficits resulting from damage to the developing nervous system. This paper, the second in a series of three articles, will present frequency, diagnosis, and management of the ocular motor deficits associated with CP. Topics for discussion will include the prevalence and type of strabismus, the effect of CP on eye movement systems, the efficacy of vision therapy for eye movement deficits, and strabismus surgery. Methods In 2002, a retrospective chart review of all cases of cerebral palsy referred to the St. Louis Childrens Hospital Eye Center was done. Detailed data on the sensory and motor deficits documented in these children was collected. Also recorded was the management strategy and response to treatment. Results Of the 131 cases reviewed (mean age 5.2 years at presentation), 84 (64%) had strabismus: 55% esotropia and 27% exotropia. Of those patients tested for eye movement disorders 67 (61%) had evidence of instability of fixation; 85% of the patients had a pursuit deficit; and 80% had some type of deficit in performing saccades. Vergence was affected in 45% of our patients. Of the patients who underwent strabismus surgery, 67% achieved success after a mean number of 2.1 surgeries. Surgical success was associated with mild or moderate CP (P < .0005), and a stable preoperative angle. Six percent of our patients underwent vision therapy for strabismus or eye movement anomalies under the direction of an outside optometrist. Conclusion Infantile strabismus is significantly more common in children with CP than in the general pediatric population. Disorders of eye movements are also very common. Based on our experience and review of the literature there is no convincing evidence that vision therapy significantly improves eye movements or visual functioning. Approximately 2 of every 3 cases of nonaccommodative strabismus associated with CP can be successfully managed with conventional strabismus surgery, though most children will require at least two surgeries to achieve alignment.

Assessment of Amplitude and Control of the Distance Deviation in Intermittent Exotropia

PURPOSE A period of monocular occlusion (patch test) has been recommended to determine the magnitude of the distance exotropia to target with surgery. The hypothesis tested by this study was that patients with good control at distance are more likely to demonstrate tenacious distance fusion following occlusion than those with poor control. The results will assist in determining which patients require a preoperative patch test. METHODS This was a prospective study of 33 consecutive patients with exotropia scheduled for strabismus surgery. All had a complete sensorimotor examination in addition to measurement of convergence amplitudes and remeasurement of the strabismus following a 60-minute patch test. RESULTS The mean change in distance deviation following occlusion was 0.5 +/- 0.6 prism diopters, and the median change was 0.0 prism diopters (P > .40). Eighteen percent had an increase in the distance exotropia of 5 prism diopters or more (tenacious distance fusion). Patients with poor control at distance by the cover-uncover test or convergence amplitude testing were unlikely to show tenacious distance fusion with the patch test (P < .001). CONCLUSION The patch test may be avoided if control over the distance deviation is poor.

High AC/A ET: Bifocals? Surgery? Or Nothing at All?

Introduction Bifocals have been the standard of care for pure high AC/A esotropia for over 100 years, though surgery for the near esotropia is being offered more and more frequently. There has been no long term study comparing the effects of bifocals and surgery with a control group prescribed single vision lenses for the distance hyperopia. Purpose This study compares the effects of these three treatment strategies on magnitude and control of the near angle, distance-near disparity, gradient AC/A ratio, binocular vision, and refractive error over a minimum follow-up interval of five years. Methods Patients with “pure” accommodative esotropia with a high AC/A were given the option of surgery, bifocals, or single vision hyperopic lenses. All were followed a minimum of five years with sensorimotor exams and cycloplegic refraction. Results Patients managed with bifocals or single vision lenses experienced a 5Δ reduction in the near esotropia, with no corresponding decrease in gradient AC/A. Patients in the Bifocal Group were less likely to undergo emmetropization, and tended to an increase in the gradient AC/A with time. Surgery resulted in a significant reduction of the near angle and collapse of the distance-near disparity. The surgical reduction of the AC/A ratio was not permanent. More patients lost stereoacuity in the Surgery Group than in the other two Groups combined. Approximately one-third of patients in each of the three treatment groups achieved long-term success, though success was achieved at a significantly earlier age in the Surgery Group. Conclusion Any of the three treatments can be effective if used under the right circumstances, though each has unique benefits and the potential for undesirable sequelae.