The incidence of corpora amylacea (CA) in the optic nerve of patients with Alzheimer's disease

Corpora amylacea (CA) are spherical or ovoid bodies 50-50 microns in diameter. They have been described in normal elderly brain as well as in a number of neurodegenerative disorders. In this study, the incidence of CA in the optic nerves of Alzheimer's disease (AD) patients was compared with normal elderly controls. Samples of optic nerves (MRC Brain Bank, Institute of Psychiatry) were taken from 12 AD patients (age range 69-94 years) and 18 controls (43-82 years). Optic nerves were fixed in 2% buffered glutaraldehyde, post-fixed in osmium tetroxide, embedded in epoxy resin and then sectioned to a thickness of 2 microns. Sections were stained with toluidine blue. CA were present in all of the optic nerves examined. In addition, a number of similarly stained but more irregularly shaped bodies were present. Fewer CA were found in the optic nerves of AD patients compared with controls. By contrast, the number or irregularly shaped bodies was increased in AD. In AD, there may be a preferential decline in the large diameter fibres which may mediate the M-cell pathway. Hence, the decline in the incidence of CA in AD may be associated with a reduction in these fibres. It is also possible that the irregualrly shaped bodies are a degeneration product of the CA.

The retinopathy of prematurity: a study of incidence and the identification of those babies at risk: myopia associated with prematurity

The ocular problems associated with premature birth have been with us ever since it was discovered that the application of high levels of inspired oxygen provided a reduction in mortality. The consequence of this reduction in mortality has been a rise in morbidity; these mortality and morbidity rates have oscillated during the attempt to find a reasonable balance. The use of contemporary technology during the attempt both to understand the premature baby's delicate physiology and to maintain life to younger and lighter babies has not yet produced stability. The incidence of typical retinal maldevelopment, retinopathy of prematurity (RCP), was analysed by serial weekly ophthalmoscopy examinations in a regional special care baby unit, 579 examinations being made on 138 babies. The best instrument for this examination was found to be a compact indirect ophthalmoscope incorporating an inverting eyepiece - the Reichert Jung monocular indirect ophthalmoscope. The optimum time for ocular examination to discover potential ocular morbidity was at 33 weeks post-conceptual age (PCA) with continued examinations to the age of 37 weeks PCA. The babies that were found to be at risk of a significant grade of RCP were found to be of a birth weight of less than 1251 grams or had an estimated gestational age at birth of 30 weeks or less. A refractive state of myopia was found to be the norm. The myopia reduced as life progressed to attain emmetropia around the age of 50 weeks PCA or 22 weeks survival. The reduction of the myopic state was found to be dependent on birth weight and gestational age at birth, the youngest and therefore the lightest being more predictable in attaining emmetropia. Refractive variations were found to be coincident with the timings of certain medical treatment regimes and a hypothesis is postulated as to the mechanism of this association.