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Biomedical subjects

R F Walters

Publications and source records attributed to R F Walters.

11 recordsLinked to original sources
PubMed1991

Long-term endothelial cell loss and breakdown of the blood-aqueous barrier in cataract surgery.

Progressive endothelial cell loss and endothelial cell loss induced at the time of surgery occurs in all eyes with rigid anterior chamber intraocular lenses (IOLs). Eyes with surgical tuck or late ovaling of the pupil following surgery have greater yearly rates of cell loss than eyes that have no complications. This progressive loss may be related to chronic uveitis from iris chafing by the implant or to direct mechanical damage to the corneal endothelium. We have demonstrated that fluorophotometry shows chronic damage to the blood-aqueous barrier in all eyes with rigid anterior chamber IOLs, but this does not correlate with the degree of endothelial cell loss. Our results suggest there is damage to the blood-aqueous barrier and to the corneal endothelium, but the damage to the latter influences progressive endothelial cell loss.

Aged↗
PubMed1990

Central retinal vein occlusion in people aged 40 years or less: a review of 17 patients.

Seventeen patients with central retinal vein occlusion aged 40 or under were reviewed. Ocular involvement was characteristically unilateral, with moderate degrees of retinal haemorrhage, little retinal ischaemia, and a tendency to optic disc swelling. Visual prognosis was good. Follow-up showed that most patients have good general health and no involvement of the fellow eye. There was little evidence to support an inflammatory aetiology or underlying vascular disease in most of the patients. An alternative explanation for the development of CRVO in young patients might be a congenital anomaly of the central retinal vein.

Adolescent↗
PubMed1989

Complications of anterior chamber lens implants and their effects on the endothelium.

A five-year follow-up study of 186 eyes which were subject to intracapsular cataract extraction and rigid anterior chamber lens implantation is reported. Ninety-two per cent of cases achieved a visual acuity of 6/12 or better. Serial corneal endothelial cell counts were performed. In 37 pairs of eyes the median difference in operative endothelial cell loss between the operated and un-operated eyes was -7.3% (95% Confidence Interval from -8.7 to -6.1%). Iris tuck occurred in 22.0% and late 'iris ovalling' developed in a further 15.6% of eyes. The median operative endothelial cell loss for those eyes with iris tuck was -9.7% and this was significantly higher than that of eyes with no long-term complications (median loss = -7.3%). The median operative endothelial cell loss for those eyes which developed late ovalling was -8.0% and this was not significantly greater than that of the eyes with no long-term complications (p = 0.745). There was a progressive median endothelial cell loss for all operated eyes and this progressive cell loss was significantly greater for those eyes with iris tuck when compared with those with no complications (p = 0.045).

Aged↗
PubMed1987

Diphtheria presenting in the accident and emergency department.

A case of diphtheria encountered in the accident and emergency department is described. In addition, 38 cases of diphtheria have been analysed, and demonstrate that, although now rare in this country, the disease still exists and its clinical features remain unchanged. It presents almost as often in the accident and emergency department as it does to the general practitioner and remains overwhelmingly a disease of children. Diphtheria is still a notifiable disease. The diagnosis must be made clinically and appropriate action taken before the bacteriological confirmation is received. This prevents unnecessary delay in treatment and makes contact tracing less arduous.

Corynebacterium diphtheriae↗
PubMed1975

Modeling static and dynamic human cardiovascular responses to exercise.

A human performance model has been developed and described [9] which portrays the human circulatory, thermo regulatory and energy-exchange systems as an intercoupled set. In this model, steady state or static relationships are used to describe oxygen consumption and blood flow. For example, heart rate (HTRT) is calculated as a function of the oxygen and the thermo-regulatory requirements of each body compartment, using the steady state work values of cardiac output (CO, sum of all compartment blood flows) and stroke volume (SV, assumed maximal after 40% maximal oxygen consumption): HTRT=CO/SV. The steady state model has proven to be an acceptable first approximation, but the inclusion of transient characteristics are essential in describing the overall systems' adjustment to exercise stress. In the present study, the dynamic transient characteristics of heart rate, stroke volume and cardiac output were obtained from experiments utilizing step and sinusoidal forcing of work. The gain and phase relationships reveal a probable first order system with a six minute time constant, and are utilized to model the transient characteristics of these parameters. This approach leads to a more complex model but a more accurate representation of the physiology involved. The instrumentation and programming essential to these experiments are described.

Analog-Digital Conversion↗
PubMedDate not supplied

Clinical ophthalmology instruction for medical students.

A ten-day ophthalmology clerkship for third-year medical students is described. The curriculum, detailed in a day-by-day syllabus, sets specific student goals, evaluates attainment of the goals by a pre-post test, utilizes a student-oriented study guide keyed to major textbrooks as core material with slide-tape and videotape supplements, and emphasizes daily supervised patient examinations. Constant modification of the clerkship on the basis of student assessment has sustained it as a popular workable clinical experience.

Audiovisual Aids↗
PubMedDate not supplied

Microprocessors as intelligent front-end devices for medical-information systems.

Computer technology has produced increasingly powerful systems whose miniaturization has spawned the term microprocessor. The role of microcomputers is optimal if they are linked to larger systems in a distributed, hierarchical network with each element performing those functions for which it is best suited. Obstacles to the development of such a network include incompatibilities in operating systems, application languages, file structures, and communication protocols. Some attempts to address these problems are briefly reviewed. Given the availability on an effective distributed hierarchy of computers, the microprocessor can be useful in a number of functions requiring rapid response and limited access to large, central data files. Examples of such activities in the medical-information environment included program development and testing, forms entry, and text-management systems. With adequate attention to the systems support as well as the development of effective application techniques, the role of microprocessor-based intelligent terminals will inevitably expand rapidly in coming years.

Computers↗