Biomedical subjects
Publications and source records attributed to J D Trobe.
The past 50 years have seen the development of ophthalmology as a sophisticated specialty with improved training programs, increased output of ophthalmologists and growth of knowledge and technology. In spite of this progress, serious problems and conflicts impair the delivery of eye care. One solution may be found in a cooperative Screening Consultation Team system, such as the one currently being evaluated at the University of Florida.
Recertification, like taxes, will never draw many supporters from the targeted group. Why should physicians who have had to survive the stiffest of scholastic labors in order to obtain the privilege of a medical education again be asked to prove their continuing worth long after graduation? Apparently because health consumers feel that physicians occupy a critical role and want more tangible evidence that they are keeping up with the explosion of medical knowledge. Dr. Trobe has sought the opinion of Dr. Melvin Rubin, who challenges the assumption that a recertification test will offer a sufficient guarantee of clinical excellence to warrant the expense to the public and the "mental anguish" to physicians, and the opinion of Dr. Sidney Wolfe, who argues that examination is a necessary (though perhaps not sufficient) protection against flagging knowledge and skill.
The authors present an algorithm, or sequential strategy, for the performance and interpretation of visual fields. Based on the principle that particular areas of the visual field are relatively vulnerable and that particular defect configurations are relatively more diagnostic, the strategy proposes certain "core maneuvers" for all initial examinations, followed by selective exploration of the vertical meridian "rectangle" and central "keyhole." This constitutes the "qualitative" portion of perimetry and combines threshold kinetic and suprathreshold static techniques. If time and patience permit, qualitative perimetry is followed by quantiative definition of defect size, depth and slope, using the requisite number of stimuli. This approach may be adapted to all visual field instruments. The interpretation of the field defects is based on assessing their localizing features.
At the present rate of training, physician extenders will shortly make up a substantial fraction of eye care providers. However, there have not yet been any published studies on the impact of this group on the delivery of services. It is the purpose of this article to outline the training categories and requirements now available for physician extenders in ophthalmology and to obtain direct feedback from ophthalmologists regarding current utilization and potential need for such personnel. Readers are asked to complete a questionnaire, which will serve as the basis for a future report on this subject.
Cost-effectiveness analysis (CEA) and cost-benefit analysis (CBA) are accounting techniques that have been applied to medical decision-making. These techniques are applied here to two alternative diagnostic strategies in the work-up of patients with "unexplained visual loss." The first uses the results of visual field examination to decide if patients should have a CT scan ("visual field strategy"), the second bypasses visual fields and orders a CT scan on all patients ("CT strategy"). The analysis reveals that the visual field strategy is cost-effective only if perimetrists are able to identify hemianopic field defects in more than 80% of cases. It is doubtful that perimetrists are presently as accurate as that. These conclusions must be considered tentative since the epidemiologic data that support them are often weak. Another drawback in applying such an analysis to medical problem-solving is that costs may not accurately reflect patient valuations and choices. Nevertheless, in forcing a more comprehensive consideration of the effects of medical decisions, CEA/CBA is likely to promote increased cost-consciousness and epidemiologic research.
Forecasts of ophthalmology manpower depend on assumptions about future supply and requirements. The two factors that influence supply are the number of residents trained and the attrition of ophthalmologists in practice. The factors that influence requirements are the estimated amount of future ophthalmic services the public will demand and the productivity of ophthalmologists. Previous forecasts have produced widely differing results because of an inadequate data base and varying theoretical assumptions. A conservative approach is to use past ophthalmologist to population ratios as a guide, and to tailor the output of ophthalmologists accordingly. A yearly reduction from 1982 to 1990 between 5% and 10% in the number of residency positions will be necessary to bring supply in line with requirements within the next thirty years.
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Several childhood multisystem disorders with prominent ophthalmological manifestations have been ascribed to the malfunction of the peroxisome, a subcellular organelle. The peroxisomal disorders have been divided into three groups: 1) those that result from defective biogenesis of the peroxisome (Zellweger syndrome, neonatal adrenoleukodystrophy, and infantile Refsum's disease); 2) those that result from multiple enzyme deficiencies (rhizomelic chondrodysplasia punctata); and 3) those that result from a single enzyme deficiency (X-linked adrenoleukodystrophy, primary hyperoxaluria type 1). Zellweger syndrome, the most lethal of the three peroxisomal biogenesis disorders, causes infantile hypotonia, seizures, and death within the first year. Ophthalmic manifestations include corneal opacification, cataract, glaucoma, pigmentary retinopathy and optic atrophy. Neonatal adrenoleukodystrophy and infantile Refsum's disease appear to be genetically distinct, but clinically, biochemically, and pathologically similar to Zellweger syndrome, although milder. Rhizomelic chondrodysplasia punctata, a peroxisomal disorder which results from at least two peroxisomal enzyme deficiencies, presents at birth with skeletal abnormalities and patients rarely survive past one year of age. The most prominent ocular manifestation consists of bilateral cataracts. X-linked (childhood) adrenoleukodystrophy, results from a deficiency of a single peroxisomal enzyme, presents in the latter part of the first decade with behavioral, cognitive and visual deterioration. The vision loss results from demyelination of the entire visual pathway, but the outer retina is spared. Primary hyperoxaluria type 1 manifests parafoveal subretinal pigment proliferation. Classical Refsum's disease may also be a peroxisomal disorder, but definitive evidence is lacking. Early identification of these disorders, which may depend on recognizing the ophthalmological findings, is critical for prenatal diagnosis, treatment, and genetic counselling.
The optimal utilization of magnetic resonance imaging in neuro-ophthalmic diagnosis is limited by errors in prescribing and interpreting scans. In a review of case material, we discovered four common prescriptive errors: 1) failure to apply a dedicated study, 2) inappropriate use of a dedicated study, 3) omission of intravenous contrast, and 4) omission of specialized sequences. The four common interpretive errors were the following: 1) failure to detect the lesion because of misleading clinical information, 2) rejection of a clinical diagnosis because an expected imaging abnormality was absent, 3) assumption that a striking imaging abnormality accounted for the clinical abnormality, and 4) failure to consider the lack of clinical specificity of imaging abnormalities. Many of these errors could be avoided by improved communication between clinicians and radiologists.
In the case presented, bilateral optic canal meningiomas produced binocular visual loss. Correct diagnosis was delayed because of inadequate and misinterpreted radiological studies. Careful radiological and surgical examination of the planum sphenoidale later suggested this as the source of both canalicular masses. The pertinent aspects of this case are reviewed in relation to information from similar cases reported previously. In the future, increased clinical suspicion and more accurate neuroradiological studies should improve the detection and afford earlier surgical treatment of meningiomas of the optic canal.
The authors report a patient presenting with a 1-week history of paresis of upward gaze as his initial manifestation of demyelinating disease. They stress that: 1) multiple sclerosis can present as Parinaud syndrome (paralysis of upward gaze); and 2) it is important to rule out a non-contour-deforming intraaxial midbrain lesion if a posterior third ventricle or pineal region mass is not identified on screening studies in these patients.