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Biomedical subjects

I M Siegel

Publications and source records attributed to I M Siegel.

At least 19 recordsLinked to original sources
PubMed2000

"On" freezing in Parkinson's disease: resistance to visual cue walking devices.

OBJECTIVE: To measure "on" freezing during unassisted walking (UW) and test if two devices, a modified inverted stick (MIS) and a visual laser beam stick (LBS) improved walking speed and number of "on" freezing episodes in patients with Parkinson's disease (PD). BACKGROUND: Multiple visual cues can overcome "off' freezing episodes and can be useful in improving gait function in parkinsonian patients. These devices have not been specifically tested in "on" freezing, which is unresponsive to pharmacologic manipulations. METHODS: Patients with PD, motor fluctuations and freezing while "on," attempted walking on a 60-ft track with each of three walking conditions in a randomized order: UW, MIS, and LBS. Total time to complete a trial, number of freezes, and the ratio of walking time to the number of freezes were compared using Friedman's test. RESULTS: Twenty-eight patients with PD, mean age 67.81 years (standard deviation [SD] 7.54), mean disease duration 13.04 years (SD 7.49), and mean motor Unified Parkinson's Disease Rating Scale score "on" 32.59 (SD 10.93), participated in the study. There was a statistically significant correlation of time needed to complete a trial and number of freezes for all three conditions (Spearman correlations: UW 0.973, LBS 0.0.930, and MIS 0.842). The median number of freezes, median time to walk in each condition, and median walking time per freeze were not significantly different in pairwise comparisons of the three conditions (Friedman's test). Of the 28 subjects, six showed improvement with the MIS and six with the LBS in at least one outcome measure. CONCLUSION: Assisting devices, specifically based on visual cues, are not consistently beneficial in overcoming "on" freezing in most patients with PD. Because this is an otherwise untreatable clinical problem and because occasional subjects do respond, cautious trials of such devices under the supervision of a health professional should be conducted to identify those patients who might benefit from their long-term use.

Aged↗
PubMed1999

Prospective analysis of changes in corneal topography after upper eyelid surgery.

PURPOSE: Some patients note a decrease in visual acuity in the operated eye after eyelid surgery. Although, the most common cause for this change is dry eye syndrome, it has been hypothesized that the symptom of blurred vision may result from a change in the corneal curvature. The study was conducted to determine if there is a change in corneal curvature after upper eyelid surgery. METHODS: Standard keratometry and corneal videokeratography (CVK) were performed 1 and 3 months after blepharoplasty (18 lids) and ptosis repair (24 lids). Pre- and postoperative images from CVK data were digitally subtracted for quantitative evaluation. RESULTS: After ptosis repair, the average dioptric change as measured by keratometry and by CVK was approximately 0.60 diopters (D); of note, nearly 30% of these patients showed transient astigmatic changes greater than 1.00 D; After blepharoplasty, the average dioptric change as measured by keratometry and by CVK was approximately 0.55 D; of note, only 11% of patients showed astigmatic changes greater than 1.00 D. CONCLUSION: Repositioning of the upper eyelid after ptosis repair or blepharoplasty may result in visually significant astigmatic changes in the central and peripheral cornea and may alter the patient's spectacle or contact lens correction.

Adolescent↗
PubMed1997

Cornea-contact lens interaction in the aquatic environment.

PURPOSE: A large population of ametropic scuba divers wear contact lenses. We discuss optics and corneal physiology, as well as the types of contact lenses that are appropriate for underwater activities. METHODS: We reviewed an extensive body of literature to formulate guidelines to aid the contact lens fitter in satisfying individual sport diver's needs. RESULTS: Optical factors such as image displacement and light wave-length shifts require that contact lenses for underwater use be suitably modified. Underwater images appear nearer and larger (requiring greater accommodation) and are made up almost exclusively of the short wavelength end of the spectrum. Correction of presbyopia, in particular, is influenced by these factors. For example, presbyopic contact lens-corrected myopes require greater near adds underwater than when viewing the same objects in air. In general, presbyopes should consider monovision correction to facilitate underwater visual tasks. Although divers wearing rigid gas permeable contact lenses run the risk of more corneal problems than soft lens wearers if conservative ascents are not adhered to, there are no compelling reasons to change lens types in patients who are already fully adapted. Soft contacts, while very stable on the eye during diving, present a greater risk of lens contamination by sea or fresh water exposure. However, the latter problems are easily overcome by using disposable soft lenses. CONCLUSION: In this paper, we present several suggestions for lens material, modifications required for underwater ametropia correction, and wearing modalities for the sport divers. An understanding of the dramatic changes that impact the properties of light, corneal physiology, and visual perception which accompany the diver below the surface will enable the contact lens fitter to design a lens appropriate to the needs of the individual patient.

Contact Lenses, Hydrophilic↗
PubMed1995

Contour resolution of the EyeSys Corneal Analysis System.

We investigated the accuracy of a conventional videokeratography instrument (Corneal Analysis System, EyeSys Laboratories) to measure contour information using specialized software developed by the manufacturer. Seven calibrated spheres were measured and the results tabulated. A contour resolution for all spheres for all reflected rings was found to be +/- 0.0047 mm, representing a 95% confidence interval. This level of resolution is high enough to obtain clinical value from using the EyeSys instrument as a contour measuring device.

Cornea↗
PubMed1993

Scapulothoracic arthrodesis in facioscapulohumeral muscular dystrophy. Review of seventeen procedures with three to twenty-one-year follow-up.

The scapula was fixed to the ribs in twelve patients who had facioscapulohumeral muscular dystrophy, in order to provide stability for activities involving the upper limbs. The duration of follow-up ranged from three to twenty-one years. Abduction, in 30 degrees of flexion, improved an average of 60 degrees, and gains in strength for carrying and lifting were reported by the patients. Complications included a brachial plexus palsy, which resolved, and a frozen shoulder. All of the patients but one were pleased with the result.

Adolescent↗
PubMed1993

Corneal contour mapping: an isomorphic approach.

Computer-assisted videokeratography holds great promise for the contact lens fitter as well as the refractive surgeon. However, conventional methods of corneal mapping, which present color-coded representations of corneal refractive power, do not provide information about corneal surface contour. We introduce a three-dimensional isomorphic corneal modeling technique that produces a freely rotatable wire-frame image that is infinitely rescalable and open to manipulation such as digital subtraction. As an illustration of this technique, we provide isomorphic representations of corneas with astigmatism induced by large pterygia.

Astigmatism↗
PubMed1992

Compartmental syndrome in Duchenne muscular dystrophy: early evaluation of an epiphenomenon leading to wasting, weakness and contracture.

Elevation of intracompartmental calf pressure in Duchenne Muscular Dystrophy can cause compartmental syndrome which accelerates mechanical muscle damage. Relief of increased pressure by fasciotomy inhibits this process. Intermittent pressure monitoring may prove of value in the routine orthopaedic management of patients with this disease. A historically controlled study to determine long term clinical benefit is in progress.

Child↗
PubMed1991

"Nintendonitis".

Explore the source record for details and available documents.

Adolescent↗
PubMed1990

Autosomal dominant congenital stationary night blindness and normal fundus with an electronegative electroretinogram.

We studied three members of three successive generations of a family with autosomal dominant congenital stationary night blindness and normal fundi. Psychophysical studies on two members showed normal final cone thresholds and mildly increased rod thresholds. Full-field electroretinograms on all three members showed normal photopic b-wave amplitudes and implicit times. Under scotopic conditions, the rod response was absent, and with a bright flash stimulus, there was a normal a-wave with no b-wave. This electronegative dark-adapted electroretinogram resembled the Schubert-Bornschein type seen in congenital stationary blindness, which has been seen only in autosomal and X-linked recessive pedigrees.

Adult↗