Open angle glaucoma, ocular hypertension, low-tension glaucoma, and refraction.

An analysis of the refractions of patients with primary open angle glaucoma, ocular hypertension (OH), and low-tension glaucoma showed that myopia occurred more frequently in each group than would be expected in a normal population of similar age. One in three of the myopes with OH had glaucomatous field defects on follow-up examination, whereas the defects developed in only one in 20 of the emmetropes and in one in 40 of the hypermetropes. These results suggest that myopic eyes are more susceptible to the effects of raised intraocular pressure than are nonmyopic eyes and that myopes with OH have a particularly high risk of the development of field defects.

Cataract: refractive error, diabetes, and morphology.

A retrospective analysis of 388 records of patients undergoing surgery for cataract between the years 1968 and 1978 showed that more women than men were admitted. About 13.7% of the patients were diabetic, and there was a striking excess of women over men with diabetes and cataract. The diabetic patients required surgery at an earlier age than the non-diabetics. Patients who had been refracted at least 5 years before surgery showed an incidence of myopia of -1.00 D or more of 25.4%. In 34% of the whole series the aphakic refraction was less than +11.00 D, again suggesting that myopes are more likely to develop a cataract than non-myopes. Posterior subcapsular lens changes alone or in combination with nuclear or cortical opacities were present in over 40% of all patients and the mean age of patients with this type of change alone was significantly lower than patients with predominantly nuclear or cortical changes. Posterior subcapsular opacities seem to be more common in Iowa than in England or India. The morphological similarity of this type of lens change with known types of secondary cataract suggests that it is not entirely a senile change but may be due to environmental or dietetic factors.

Lens thickness in early cataract.

The search for environmental factors associated with cataract has produced conflicting evidence and one possible reason may be that environmental influences are initiating events occurring perhaps for short periods many years before loss of sight from cataract. It is important, therefore, to be able to detect the earliest changes of cataract formation so that epidemiological studies have a better chance of detecting environmental factors. Two possible indicators of early cataract are delayed growth of the lens and abnormalities of the anterior subcapsular clear zone of the lens as observed on slit-lamp microscopy. A series of patients with early lens changes was compared with control subjects in respect to these two factors. Lens thickness was measured by a simple optical method. The mean thicknesses of the lens in patients with early cortical or posterior subcapsular lens changes were significantly less than that of age matched controls. 60% of lenses with early cataract of all types were found to have a deficient or absent anterior subcapsular clear zone. Lens thickness and the appearance of the anterior subcapsular clear zone are easy to measure and observe through an undilated pupil. Although the prognostic value of the results is uncertain in individual cases owing to the rather wide scatter of results in normal eyes, such observations could be of value in comparative studies of populations.

Depth measurement with the slit-lamp microscope.

The sagittal distance of ocular structures can be obtained with a slit-lamp microscope providing the movement of the slit-lamp can be measured. A simple device consisting of a pointer attached by a spring clip to the axle of a Haag-Streit 900 slit-lamp is described. The pointer rides over a scale which slides with the slit-lamp. Comparisons of anterior chamber depth and lens thickness showed a high correlation between this optical method and ultrasound measurements.

The ocular pulse and intraocular pressure as a screening test for carotid artery stenosis.

The ocular pulse and applanation tension were measured with a recording applanation tonometer in 38 patients suspected of having internal carotid artery stenosis. Abnormalities of the ocular pulse amplitude, intraocular pressure, or combinations of these two measurements were found in 23 (82%) of 28 patients who were subsequently found to have angiographic evidence of 50% or more stenosis of one or both internal carotid arteries. Of 10 patients without angiographic evidence of carotid stenosis the ocular pulse amplitude, intraocular pressure, or both were abnormal in five, but two patients had an ocular cause for abnormality and two of the remaining three had evidence of carotid disease in the form of atheromatous plaques. These results suggest that measurement of the amplitude of the ocular pulse in addition to the intraocular pressure can predict the presence of carotid artery stenosis and indicate the need for further investigation. If a tonometer capable of measuring the pulse amplitude was used routinely in ophthalmic examinations, it would provide a useful screening test for the early diagnosis and treatment of carotid artery disease and might thereby reduce the frequency of strokes.

Family studies in glaucoma.

Two groups of patients with a family history of chronic open-angle glaucoma were compared with a normal population of 5919 individuals studied during the Bedford Glaucoma Survey. The mean screening intraocular pressure was significantly raised in both groups with a family history of chronic open-angle glaucoma. The prevalence rate of a raised intraocular pressure was 3.81 times that found in the normal population. This relationship was maintained when age-dependent prevalence rates were evaluated. No correlation between raised intraocular pressure and type of familial involvement could be determined. A 10- to 12-year follow-up of one group with a family history for open-angle glaucoma (101 patients) showed that 3% developed confirmed glaucoma, while an additional 5.9% were diagnosed as suspected chronic open-angle glaucoma. A letter survey of this group showed that 9 out of 63 respondents knew of additional family members who developed glaucoma over this 10-12-year period.

Simple method of determining the axial length of the eye.

By photographing the corneal reflex in two positions of gaze and measuring the radius of curvature of the cornea it is possible to calculate the radius of rotation of the eye. The measurements obtained in this way showed a high correlation with refraction in a series of 80 eyes. The axial length obtained by this method was about 3 mm greater than that obtained by ultrasonographic or x-ray methods, and the reasons for the discrepancy are discussed.

Survey of ophthalmic conditions in a Labrador community. I. Refractive errors.

Of the 745 available members of the population of Nain in Labrador 650 (87%) were screened for refractive errors and ocular disease. Refraction by retinoscopy was done in 553 and axial length measured by an optical method in 514. The results showed that the incidence of low degrees of myopia was higher in Inuit (Eskimos) and those of Mixed Inuit-Caucasian blood in the age groups 10 to 40 than in those over 40. 75% of the myopes came from 20 families in which myopia was present in 2 or more generations. Although there was no significant correlation between the refraction of parents and offspring, there were significant correlations between them for axial length. The axial lenths of the myopic eyes of the Inuit and Mixed populations were significantly longer than emmetropic and hypermetropic eyes. The younger memebers of the population were taller than their parents, and except in female Caucasians axial length showed a significant positive correlation with height. More myopes than emmetropes and hypermetropes achieved grade 8 or more in school. It is suggested that the increased incidence of myopia in the younger age groups might be due to environmental factors interfering with the process of emmetropisation in eyes with a genetic predisposition to myopia by virtue of inheriting a slightlt longer eye. Better nutrition resulting in an increase in stature may also have had some influence.

Comparison of ultrasonic and photographic methods of axial length measurements of the eye.

The axial length of 25 eyes was measured by the photographic method and by ultrasonography. The photographic measurements were consistently larger than the ultrasonic, but analysis gave a correlation coefficient of r = 0-8483. The results suggest that the centre of rotation of the eye lies posterior to the anatomical centre of the globe. Using an empirical method of calculation and allowing for an error of +/-0-3 mm in the ultrasonic measurement, the photographic results were within +/-0-5 mm in 13 eyes and +/-1-0 mm in 7 eyes. The photographic method may be helpful as a guide to the power of intraocular lens implants and for comparing axial lengths in population studies.

Plasma vitamin A and beta-carotene in retinitis pigmentosa.

Plasma levels of vitamin A and beta-carotene were measured by spectrophotometry in 39 patients with genetically determined retinitis pigmentosa, No difference was found between the levels in these patients and the levels in a control group.

Single treatment laser iridotomy.

A technique is described for producing an iridotomy in the treatment of closed-angle and secondary glaucoma using a single pulse from a dye laser. It was successful in 28 out of 32 eyes treated, and no significant complications were encountered.

The ocular pulse.

A recording applanation tonometer was used to examine the ocular pulse in normal subjects and patients with ocular hypertension, open angle glaucoma and low tension glaucoma. The mean pulse amplitude of right eyes of normal subjects was 2.84 mm Hg +/- 1.16 and 2.83 mm Hg +/- 1.18 for left eyes. Only 2% of subjects showed an interocular difference in pulse amplitude of more than 0.5 mm Hg. There were significant differences in pulse amplitude with refractive errors. Hypermetropic eyes had the largest pulse amplitude and myopic eyes the smallest. There was no significant correlation between pulse amplitude and intraocular pressure or age in normal subjects. The mean pulse amplitude of eyes with open angle glaucoma was significantly higher than that of normals. The mean pulse amplitude of a small number of eyes with ocular hypertension was significantly higher and eyes with low tension glaucoma had significantly lower pulse amplitudes than normal subjects.

Survey of ophthalmic conditions in a Labrador community: II. Ocular disease.

An ophthalmic examination of 87% of the resident population of Nain, Labrador (latitude 56 degrees 33'N) was carried out, and the findings in 330 Inuit, 236 persons of mixed racial ancestry (Inuit-Caucasian) and 80 Caucasians were analysed. Legal blindness was present in 1.2% of the survey population, compared with 1.6% of the study population of the Arctic Ophthalmological Survey of 1970-71. Of the age group 52 to 85 years, 10.8% were legally blind, compared with 0.6% of the same age group surveyed in the Framingham (Massachusetts) Eye Study. The leading causes of unilateral or bilateral blindness in Nain were trauma, especially in the Inuit, and spheroidal degeneration (Labrador keratopathy); neither senile macular degeneration nor diabetic retinopathy had caused legal blindness. External diseases, particularly spheroidal degeneration (which affected 19% of the population), phlyctenular keratoconjunctivitis and epiblepharon, were the commonest diagnoses in Nain. No diabetic retinopathy was detected, but evidence of toxoplasmosis was encountered. Compared with the study population of the Arctic Ophthalmological Survey, the Nain population had a higher prevalence of spheroidal degeneration and other corneal diseases.

Intraocular inflammatory disorders: uveitis.

Emphasis on the association between intraocular inflammatory disorders and systemic disease guides the clinical descriptions of acute and chronic uveitis in this article. Practical information on establishing the diagnosis and treating the condition is provided.

Cross reactivity between Klebsiella pneumoniae and ocular tissue.

Klebsiella pneumoniae has been implicated as a possible aetiological agent in ankylosing spondylitis and acute anterior uveitis. Cross-reactivity between antigens of klebsiella and bovine vitreous has been reported. In the present study sera from rabbits immunised with Klebsiella pneumoniae was tested against fresh guinea pig and human ocular tissues using immunodiffusion and immunofluorescent methods. No cross-reactivity between klebsiella and the ocular tissues used could be demonstrated by these techniques.

Older men's experiences of community-based health checks in Knowsley, UK.

A study using both qualitative and quantitative methods was undertaken to examine the impact of community-based health checks on men in Knowsley, UK. The main objective was to understand whether community-based health checks targeted at specific geographical and age groups were an effective way of improving health in men. Interviews were conducted with 50 service users, and a completed postal questionnaire was received from 178 men who had attended during the service's pilot period. Results indicated that men were generally satisfied with both the content and structure of the health checks. Men spoke favourably of the service they had received, particularly in comparison to their previous experiences of primary care. They reported enjoying using a service that allowed them to examine their own health in a comfortable environment. Knowledge was provided to a group whose awareness of health matters was often poor, and the vast majority of men reported making a variety of positive lifestyle changes as a result of attending. Reported improvements to health included giving up smoking, reducing alcohol consumption, increasing exercise and eating more healthily. The study suggests that services of this nature deserve careful consideration by health care professionals and policy-makers.