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Biomedical subjects

B Wick

Publications and source records attributed to B Wick.

18 recordsLinked to original sources
PubMed1992

Arnold-Chiari malformation.

Arnold-Chiari malformation is a congenital malformation of the skull near the foramen magnum in which the cerebellum and the medulla are caudally displaced. This herniation of the brainstem causes down-beat nystagmus and oscillopsia, the most commonly presenting sign and symptom, respectively. Differential diagnoses for the Arnold-Chiari malformation include, but are not limited to, demyelinating disease, tumor, and vascular disorders. Symptoms will generally worsen with time and may even be brought on during exercise or valsalva maneuvers. A correct diagnosis can lead to timely surgical intervention which can improve the quality of eye movements. Treatment generally involves the surgical decompression of the surrounding spinal tissue.

Adolescent↗
PubMed1992

Treatment options in intermittent exotropia: a critical appraisal.

Clinical opinions regarding treatment of intermittent exotropia (IXT) vary widely and there is controversy as to which treatment modality is most successful. This paper reviews the clinical literature related to five different treatment modalities used for IXT: overminus lens therapy, prism therapy, occlusion therapy, extraocular muscle surgery, and orthoptic vision therapy. Based upon review of 59 studies of treatment of IXT, and using each author's stated criteria for success, the following pooled success rates were revealed: over-minus lens therapy (N = 215), 28%; prism therapy (N = 201), 28%; occlusion therapy (N = 170), 37%; extraocular muscle surgery (N = 2530), 46%; and orthoptic vision therapy (N = 740), 59%. Success rates for IXT surgery differed depending upon whether a functional (43%) or cosmetic (61%) criterion was used to evaluate treatment success. These pooled success rates must be viewed carefully because nearly all the studies suffer from serious scientific flaws such as small sample sizes, selection bias, inadequately defined treatments and success criteria, absence of statistical analysis, and results reported in a manner that makes interpretation difficult. These problems indicate the need for a careful, circumscribed, and well controlled clinical trial to study the efficacy of different treatment modalities in remediating IXT.

Contact Lenses↗
PubMed1992

Binocular vision section.

The participants at the 1991 Meetings of the Section on Binocular Vision and Perception presented a substantial amount of valuable theoretical and clinical information. There was considerable and valuable interaction between the audience and panel, especially after the symposium concerned with new techniques and how to use them. The exchange of specialized knowledge through discussions at symposiums such as these represents one of the best features of Academy meetings. These symposiums reemphasize and remind us of the expertise of our Academy members in management of binocular vision anomalies.

Dyslexia↗
PubMed1992

Re-evaluation of the four prism diopter base-out test.

The four prism diopter base-out (4 delta BO) test is often recommended for use as an objective assessment of binocular visual function in patients with suspected microstrabismus or central suppression; however, many aspects of the test are unknown. In this series of investigations we evaluated: (1) inter-observer agreement between 2 examiners, using 15 subjects; (2) types of eye movements made and prevalence of the various response types demonstrated in 212 children and 116 adults with normal binocular vision, and 10 children and 4 adults with abnormal binocular vision; and (3) repeatability of test results for 22 subjects evaluated on two separate occasions. In addition, using an SRI Eye-tracker, we documented the eye movements made while testing 2 subjects with small angle strabismus and 4 subjects with normal binocular vision. We found the following results: (1) inter-observer agreement is high; (2) both children and adults exhibit many atypical responses, whether or not they have normal binocular vision; (3) diplopia awareness does not differentiate between subjects with normal and abnormal binocular vision; and (4) 4 delta BO test results are not repeatable. Due to frequent atypical and variable responses in subjects with or without normal binocular vision, we suggest the examiner use caution when making a diagnosis based solely on the 4 delta BO test.

Adult↗
PubMed1992

Anisometropic amblyopia: is the patient ever too old to treat?

Amblyopia is an example of abnormal visual development that is clinically defined as a reduction of best corrected Snellen acuity to less than 6/9 (20/30) in one eye or a two-line difference between the two eyes, with no visible signs of eye disease. We describe a sequential management program for anisometropic amblyopia that consists of four steps: (1) the full refractive correction, (2) added lenses or prism when needed to improve alignment of the visual axes, (3) 2 to 5 h/day of direct occlusion, and (4) active vision therapy to develop monocular acuity and improve binocular visual function. We examined records of 19 patients over 6 years of age who had been treated using this sequential management philosophy. After 15.2 (+/- 7.7) weeks of treatment the Amblyopia Success Index (ASI) documented an average improvement in visual acuity of 92.1% +/- 8.1 with a range from a low of 75% by a 49-year-old patient to a maximum of 100% achieved by 42.1% of the patients (8 of 19). Patients who had completed therapy 1 or more years ago (N = 4) maintained their acuity improvement. From these results we conclude that following a sequential management plan for treatment of anisometropic amblyopia can yield substantial long-lasting improvement in visual acuity and binocular function for patients of any age.

Adolescent↗
PubMed1992

Rapid- and slow-velocity vergence eye movements.

Previously we have measured rapid-velocity vergence responses to targets at different distances that provided no disparity or accommodative stimulation. To evaluate the possibility that this rapid-velocity vergence occurs during saccades, the latencies of eye movement between two long dim luminous rods were compared under two conditions. Rapid-velocity vergence with an average latency of approximately 300 ms was elicited when subjects alternately viewed horizontal rods at distances of 38 and 78 cm, and with a vertical separation of 5.2 degrees. Horizontal saccades with a comparable latency were measured when the rods were equidistant and oriented vertically. The correlation between the mean latencies of vergence and saccadic movements was 0.97, suggesting that the two movements occurred together. In a second experiment vergence responses were measured when the subject looked between a bright vertical line on a screen at 76 cm and a second pair of lines (vertically displaced between 0.15 degrees and 3 degrees) with crossed disparity to simulate a target at 38 cm. Slow-velocity vergence often occurred alone when the vertical separation between targets was small; rapid-velocity vergence intruded when the separation between the targets was larger. The results can be accounted for if proximity and disparity stimulation act through a single vergence controller, the output of which produces slow- or rapid-velocity vergence depending upon whether the saccadic system is concurrently active.

Adult↗
PubMed1979

Prevention and care of strabismus in infants and pre-school children.

Care of children at risk of developing strabismus is discussed. Recommended care consists of parental counseling combined with early and periodic examinations. Examinations should begin by age 3 weeks and continue at 3-6 month intervals until the child reaches age 5. Treatment of strabismus or amblyopia should begin as soon as these conditions exist. Using recent electrophysiological research as a background, a model care for infants with congenital strabismus is presented. Care reports are presented describing results of orthoptic treatment of non-congenital strabismus.

Age Factors↗
PubMed1977

Vision training for presbyopic nonstrabismic patients.

Home vision training was prescribed for 161 presbyopic patients (ages 45 to 89) who had vision-related symptoms and convergence insufficiency or visual skills deficiencies. Most patients required 10 weeks or less of treatment, the longest treatment period being 15 weeks. Elimination of the symptoms and improved responses on certain optometric tests was achieved by 92% of the patients. Evaluation 3 months after therapy indicated that 77 patients required additional training, the older patients requiring it more often, to retain the initial improvement.

Age Factors↗
PubMed1977

Binocular vision therapy for general practice.

Guidelines are given for selection of patients who need binocular visual therapy. These guidelines are useful for the optometrist who wishes to start binocular vision training in his practice. Treatment techniques for each type of binocular problem are discussed. Case reports are included which detail diagnosis and treatment.

Accommodation, Ocular↗
PubMed1976

A vision profile of American Indian children.

In an unselected study, Modified Clinical Technique screening plus keratometry was done on 398 American Indian grade school children. The results are compared to screening results for Caucasin grade school children.

Astigmatism↗
PubMed1976

A home pleoptic method.

A method of initiating an after-image in an amblyopic eye with eccentric fixation by using Haidinger's brush for fixation control is described. This technique makes home pleoptics possible.

Afterimage↗
PubMed1976

Comparison of vision screening by lay and professional personnel.

A previously described vision screening procedure was administered to 652 elementary school children, using lay volunteers. These students were later screened by optometrists, using the Modified Clinical Technique (MCT). Using MCT as the standard, the lay screening correctly identified 90% of the children; the incorrect identifications included 28 children (4.3%) as false negatives and 36 children (5.5%) as false positives. Analysis indicates a lower cost for the combined lay and professional screening than for professional screening alone.

Allied Health Personnel↗