Biomedical subjects
Publications and source records attributed to H J Wisnicki.
Deteriorated accommodative esotropia is a residual esotropia with treatment in previously controlled esotropia. Hypothesized etiologies include occlusion, undercorrected hyperopia, increased AC/A ratio, increased or undetected hyperopia, microtropia, delay in treatment and poor compliance.
PURPOSE: To investigate the controversial origin of the foveal granular pattern at the center of the entoptic Purkinje vessel shadows. Both phenomena may be vividly elicited by oscillating a focused spot of light across the scleral surface of the eye in a circumferential direction. METHODS: The site and pattern of oscillation of the light spot were varied and were correlated with the appearance of the foveal granular pattern. Movement of the granular pattern relative to a foveal afterimage was also observed. RESULTS: Oscillation of the light in a meridional direction abolishes the granular pattern. Oscillating illumination through the central pupil can elicit Purkinje vessel shadows but not the characteristic foveal granular pattern. With transscleral illumination, the granular pattern oscillates with an "against" motion with respect to the motion of the Purkinje vessel shadows and with a "with" motion with respect to apparent motion of an afterimage serving as a fixed anatomic reference, and it is displaced from the center of the foveal avascular zone in the visual direction away from the source of illumination. CONCLUSIONS: These observations strongly suggest that the foveal granular pattern is a random moire pattern produced by spatial aliasing as the striated light pattern cast by the parafoveal nerve fiber elements sweeps over the photoreceptors in the form of a faint, high-spatial-frequency, irregular grating. An anatomic section of the fovea reveals the necessary geometry for production of such striated patterns, and the Nyquist frequency for the foveal photoreceptor mosaic supports the spatial aliasing effect. Also, a grating moving over a stationary random dot background demonstrates the origin of the "against" motion that is characteristic of the foveal granular pattern.
The apparent optical axis of an implanted intraocular lens (IOL) can be located by alignment of the examiner's hand light with the third and fourth Purkinje images from the front and back surfaces of the IOL. Tilt of the IOL can be estimated (or measured with an arc perimeter) by the angle between the apparent optical axis and the patient's line of sight (actual tilt approximately 0.85 x apparent tilt). Decentration of the IOL is easily detected, equal to the distance of the IOL optical axis from the center of the pupil. This simple technique can be used through the natural pupil with posterior chamber IOLs, providing the optical axis of the malpositioned IOL still passes through the pupil.
With the advent of extremely rapid, powerful, compact, and inexpensive microcomputers, a revolution in data manipulation is ongoing. We have customized and used for over two years prepackaged software to track residents' operative experiences in the Department of Otolaryngology at Jefferson Medical College of Thomas Jefferson University, Philadelphia. An attempt is presently being made to develop a similar system that might be utilized by all otolaryngology teaching programs and thus enable the collection and review of residents' operative experiences nationally. A basic, relational database system is proposed for entering resident caseload data and generating reports for periodic review.
The Wilmer Information System is a computerized medical information system used for the storage and retrieval of data pertaining to patient demographics, diagnosis, and therapy. The heart of the system is an expandable, hierarchical code based on International Classification of Diseases, 9th Revision (ICD-9) diagnosis codes and Physicians' Current Procedural Terminology procedure codes. Customized coding sheets containing highly specific diagnosis and procedure codes have been designed for each subspecialty area in ophthalmology. Interactive database management software facilitates data entry and retrieval. The system can be used to search for patients who meet very specific criteria, or to produce cumulative visit reports and summary statistics.
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Adjustable suture strabismus surgery may reduce the frequency of reoperations by reducing immediate postoperative over- and undercorrections. We reviewed 290 strabismus procedures performed with an adjustable suture technique. Thirty-five patients required additional surgery, for a reoperation rate of 9.7%. Reoperation frequencies for patients undergoing non-adjustable procedures average approximately 20% in our experience and in reported series. Our low reoperation rate with adjustable strabismus surgery supports our clinical impression that more accurate results are possible with this technique in appropriate patients.
Residency training involves surgery by resident surgeons at various levels of experience and proficiency, supervised by an experienced attending physician. We reviewed the results of strabismus surgery performed at four institutions with two residency training programs. Five hundred twenty-two cases with follow up greater than 6 weeks were evaluated. These cases included 315 attending procedures and 207 resident procedures under direct attending supervision. Success was defined as a strabismic deviation of 8 prism diopters or less. Average postoperative follow-up was 57 weeks and did not differ between groups. There was no statistical difference between the resident success rate of 58% (121/207) and the attending success rate of 69% (217/315) after adjusting for population differences. The average final deviation of the patients postoperatively was 7 delta for the attending group and 10 delta for the resident group. Amblyopia was significantly more frequent in the resident cases (P < .001). Adjustable sutures were used significantly more often in attending cases (P < .0001). This study supports the premise that resident strabismus surgery is as successful as attending surgery.
In homoplastic keratomileusis, keratophakia, and epikeratophakia, the corneal tissue that provides the final refractive lenticule undergoes a conformational change when frozen. Because corneal tissue is composed primarily of water, an assumed value of 9.08% (approximate volumic percentage expansion of water when frozen) is frequently used for the increase in thickness, or freezing increment, rather than measuring it directly. We evaluated 32 cases of clinical keratophakia and found the increase in thickness to average 37 +/- 21%. In this series of 32 cases, the percentage of patients with a greater than 4 D residual refractive error was 16%. If an assumed freezing increment of 9.08% had been used, the percentage would have been 28%, with two-thirds of these 28% manifesting a marked undercorrection. Because of a lack of studies documenting the behavior of corneal tissue following cryoprotection and freezing, it is suggested that measurements be taken during homoplastic surgery to minimize the potential for significant inaccuracy in obtaining the desired optic result.