Biomedical subjects

Bruce Wick

Publications and source records attributed to Bruce Wick.

5 recordsLinked to original sources

PubMed2003

Post-traumatic pseudomyopia.

BACKGROUND: Many clinicians have noted that patients demonstrate a myopic refractive change following Traumatic Brain Injury (TBI). This apparent myopic shift disappears with cycloplegia, yet stubbornly reappears as soon as the pharmaceutical effect wears off. We propose that this shift is secondary to an irritative lesion that affects the parasympathetic innervation, resulting in ciliary body contracture. The dilemma for the clinician is whether to provide the immediate relief of clear distance vision by prescribing additional minus lenses, or to work toward attempting to re-establish the baseline refractive error. CASE REPORTS: The natural history of post-traumatic pseudomyopia in our experience involves one of the following three courses: (1) a transient condition that will occasionally resolve; (2) the typical case, a recalcitrant condition that will resolve under cycloplegic intervention, but immediately return as the cycloplegic wears off; or (3) a less-common subgroup of patients who continue to show an increase in myopia over time. Our description of these cases demonstrates management strategies (including atropinization) to relax accommodative spasm, traditional vision therapy techniques aimed at loosening the accommodative system, and refractive corrections. CONCLUSIONS: Pseudomyopia is one of many ocular and behavioral sequelae following TBI. By understanding the natural course and potential management options for post-traumatic pseudomyopia, the clinician will be better prepared to deal with these challenging cases. Flexibility is required, since options that work with one patient may prove ineffective with another. Counseling the patient as to potential outcomes given the natural history of this condition helps establish more-realistic expectations by the patients being treated.

Accommodation, Ocular↗

PubMed2003

The symptomatic patient with normal phorias at distance and near: what tests detect a binocular vision problem?

PURPOSE: Patients often manifest symptoms that appear to be related to binocular distress. Many of these patients have normal heterophoria at distance and near, making the etiology of such symptoms perplexing. We performed a visual examination of patients having normal heterophoria at distance and near in order to investigate which visual analysis tests differentiate symptomatic from asymptomatic patients. METHODS: Eighty subjects (30 symptomatic, 50 asymptomatic) with ages between 18 to 35 years of either sex and any race were pooled based on vision-symptom level determined by a 9-question standardized visual-symptoms questionnaire scored using a 100-point scale (asymptomatic: score > or = 85; symptomatic: score < or = 75). Inclusion/exclusion criteria included vision correctable to 6/6 (20/20) Snellen acuity or better in each eye, normal phorias, no latent cyclovertical heterophoria, and normal ocular health. RESULTS: Of the 30 symptomatic patients, 18 had reduced vergence facility response using 3 pd base-in/12 pd base-out loose prism at distance (n = 10; t-score = 2.41, p < 0.02, d = 76) and near (n = 15; t-score = 3.32, p < 0.01, df = 78) with a significant difference beyond the 0.02 level. No other test including measurement of accommodation, showed a significant between-group difference. However, three patients with normal vergence facility (distance and near) showed a reduced binocular accommodative facility response (+/-2.00 D at 40 cm). CONCLUSION: Given a patent with asthenopia, normal phorias, and visual acuity, a differential diagnosis may be made based primarily on using vergence facility and accommodative facility testing. From a clinical standpoint, the results expedite diagnosis of binocular vision abnormalities and direct treatment.

Accommodation, Ocular↗

PubMed2002

Clinical testing of accommodative facility: Part 1. A critical appraisal of the literature.

BACKGROUND: Accommodative facility testing is used in clinical care to assess functioning of the ocular accommodative system. The current clinical standard (binocular assessment using +/- 2.00 D lenses at 40 cm with a vectographic suppression check) was first described nearly 20 years ago as part of the last comprehensive review of the literature. The standard accommodative facility test imposes a variable requirement on patients of different ages who have a wide range of accommodative amplitudes. METHOD: In this article, we critically reviewthe present body of literature on accommodative facility testing, with emphasis on the relation between symptoms, accommodative amplitude, and the results found during accommodative facility testing. RESULT: We include discussion of the five broad categories of accommodative facility studies: (11 recommendations for testing criteria; (2) normative data investigations; (3) reliability and variability assessment; (4) relation between accommodative facility and symptoms; and (5) other relationships (e.g., effect of test parameters on accommodative facility). CONCLUSION: Given the substantial variation in demand when testing patients of different ages (amplitudes), it is not surprising that a significant variation in responses has been reported in the clinical accommodative facility literature. Future clinical investigation of accommodative facility would benefit from a systematic investigation into the relationship between age and amplitude. The presence or absence of symptoms needs to be considered so that results of testing can be analyzed in relation to the severity of binocular vision-related symptoms.

Accommodation, Ocular↗

PubMed2002

Clinical testing of accommodative facility: part III. Masked assessment of the relation between visual symptoms and binocular test results in school children and adults.

BACKGROUND: Accommodative facility is commonly assessed using +/- 2.00 lenses at 40 cm. Significant differences have been demonstrated on binocular facility testing between symptomatic and asymptomatic children; studies on adults have not replicated these results. We evaluate the relation between symptoms and binocular amplitude-scaled facility (equivalent stimulus for each subject based on individual amplitude). METHODS: Optometry students (N = 98) and school children IN= 152) participated in a vision screening. A 9-question standardized questionnaire quantified symptoms. Binocular accommodative facility was assessed using random presentation of standard and amplitude-scaled facility, without knowledge of symptom level. Subjects with abnormal binocular vision were excluded from data analysis. RESULTS: For children, both amplitude-scaled (p = 0.0004). and standard accommodative facility (p = 0.0055) significantly differentiated symptomatic from asymptomatic responses. For adults, amplitude-scaled responses were significantly different (p= 0.0228) between symptomatic and asymptomatic subjects; standard testing results were not (p = 0.2013). CONCLUSION: Binocular amplitude-scaled facility testing (test distance 45%, lens power range 30% of push-up amplitude) identifies symptomatic adults at high significance level. And both children and adults perform similarly on amplitude-scaled testing. These results suggest that amplitude-scaled binocular accommodative facility should be the test of choice for evaluation of patients between the age of 8 years and the onset of presbyopia. Patients who perform less than 10 cycles per minute are likely to be symptomatic.

Accommodation, Ocular↗

PubMed2002

Clinical testing of accommodative facility: part II. Development of an amplitude-scaled test.

BACKGROUND: Standard accommodative facility testing, using +/- 2.00 D lenses @ 40 cm, stresses a much different proportion of the available accommodation for a 10-year-old patient with a binocular accommodative amplitude of 12 D and a 35-year-old patient with a binocular amplitude of 5 D. This may explain why research using adult subjects has failed to associate reduced accommodative facility with symptoms. METHODS: For 19 adult subjects with normal age-related amplitudes of accommodation, accommodative facility was measured with the standard test (+/- 2.00 D @ 40 cm) and 36 experimental combinations of test distance demand and lens power range, based on percentages of each individual's amplitude. In a masked study. these results were compared to symptom scores, quantified by a 9-item quality of vision questionnaire. RESULTS: The strongest relation of facility with symptoms was for the 75% distance demand/30% power range (p = 0.0216), with six other combinations also significant. The standard test combination did not significantly differentiate symptomatic from asymptomatic subjects (p = 0.1 515). The combination of the 45% distance demand/30% power range was significantly related to symptom score (p = 0.0315; r = -0.47603). CONCLUSION: Amplitude scaled facility testing provides the same percentage test distance and range of amplitude stimulated for all patients. The 45%/30% test combination differentiates symptomatic from asymptomatic subjects better than the standard test (+/- 2.00 D @ 40 cm) and is the one we suggest for future clinical investigation. Care should be taken when testing symptomatic patients over a long period of time, as they may compensate by relying on a predictor operator during the highly repetitive accommodative facility test, thus achieving a more-rapid response.

Accommodation, Ocular↗