Retrospective study of optometric referrals.

We undertook a retrospective study of the referral patterns of optometrists. During the study period 13,107 patients had been seen, of whom 2.86% had been referred. Of the referred patients, 66.67% were referred to an ophthalmologist via the general practitioner, 25.87% to their general practitioner alone, and 7.47% directly to an ophthalmologist. The conditions for which patients were referred are given along with information on any supplementary tests used. The effect of practitioner age and seasonal variations on referrals was also determined. The role of the optometrist in screening for ocular disease is discussed.

The topography of the P1 component of the flash visual evoked response.

The scalp topography of the P1 component of the human flash visual evoked response was investigated by means of the biologic brain mapping system. Thirty subjects, ranging in age from 21 to 84 years, had flash visual evoked responses recorded using the standard 10-20 electrode positions referred to a balanced noncephalic reference. The subjects were divided by age into three groups: young, middle and old. A P2 component was recorded over the occipital region for all three groups and a frontal negative component was found to occur concurrently with the P2 occipital component. Neither the young or the middle age groups showed an identifiable P1 component. However this component was clearly present in the older group at 76 msec. The distribution of this component was more widespread anteriorly than the P2 component. In both the middle and the older age groups an earlier frontal negative component was present at around 75 msec; no such component was recordable in the young. This work suggests that the development of the P1 component during middle age is preceded by the development of a frontal negative component of around the same latency.

Referral patterns to an ophthalmic outpatient clinic by general practitioners and ophthalmic opticians and the role of these professionals in screening for ocular disease.

Case notes of 1113 consecutive new patients referred to a consultant ophthalmologist at a district general hospital were reviewed to determine the source and efficacy of referrals and the current screening practices of general practitioners and ophthalmic opticians. General practitioners initiated referral in 546 cases (49%) and ophthalmic opticians referral in 439 (39%). Visual loss or visual disturbance was the most important single reason for referral (345 cases; 31%), followed by suspected glaucoma (145 cases; 13%), abnormalities of binocular vision (140; 12.5%), disorders of eyelids or ocular adnexa (127; 11%), and red eye (86; 8%). General practitioners referred many more patients with disorders of the eyelids and adnexa and ophthalmic opticians many more patients with suspected glaucoma. Ophthalmic opticians were far more likely than general practitioners to refer patients with suspected glaucoma correctly. A total of 180 patients (16%) were referred from ocular screening, in 149 cases by ophthalmic opticians and in 10 by general practitioners. Seventy patients had glaucoma or incomplete features of glaucoma, all of them referred by ophthalmic opticians. Of eight diabetic patients referred by ophthalmic opticians, three had asymptomatic disease and in two diabetes was diagnosed as a result of ocular screening. No patient was referred for asymptomatic diabetic retinopathy from screening by general practitioners. Ophthalmic opticians were more likely than general practitioners to diagnose retinopathy requiring photocoagulation. Use of a community based service to screen for glaucoma could save unnecessary consultant outpatient appointments. A similar service could facilitate detection of diabetic retinopathy at a stage when treatment is most effective.

Cluster analysis in visual field quantification.

The central visual fields of 2165 normal and 106 glaucoma eyes were measured using a threshold related suprathreshold strategy. The effects of altering the cluster radius in normals and glaucoma eyes sheds light on the nature of defects in these two groups. It is estimated that approximately 13% of normals have clusters; the great majority of these individuals have one cluster of two defects. Most clusters in normals are formed artefactually due to angioscotoma and/or physiological variations in the blind spot position. Clusters due to other factors occur rarely. Clusters are found with equal frequencies in the superior and inferior fields in normal eyes, but with a greater frequency in the superior field in glaucoma eyes. The use of clusters in quantification is both sensitive and specific. Using results from this large sample and looking at other visual field properties, it is possible to devise weighted probability indices to score visual fields.

A comparative evaluation of timolol maleate and pilocarpine in the treatment of chronic open angle glaucoma.

Ninety-two eyes with newly-diagnosed chronic open angle glaucoma (COAG) were treated in a randomised prospective trial with either timolol or pilocarpine. Their visual field survival was monitored on a 3-monthly basis over 2 years using both Goldmann and Friedmann perimetry. Concomitant tonometric data was derived by applanation. Fields were assessed and quantified using algorithms designed to give the greatest sensitivity for glaucomatous field loss. Microcomputer programmes specifically designed for this purpose were used in the data collection and subsequent analysis.

Frequency distribution of early glaucomatous visual field defects.

The optimization of visual field screening programs for glaucoma requires precise knowledge of where glaucoma defects occur and whether any relation exists between the size of defects and the associated retinal disease. The visual field results from 109 eyes of patients with early glaucomatous damage were investigated with a Friedmann Mark II Visual Field Analyser. The frequency distribution of scotomas as a function of location demonstrated that the tested field could be divided into four zones, one where scotomas occur frequently, one where scotomas occur a reasonable number of times, one where scotomas occur rarely, and one which corresponds to the blind spot (BS) region. The distribution of scotoma size in the first three zones was found to be about the same. Differences among the distributions of defects measured in this study and those of previous studies are attributed to different examination techniques.

Glaucoma assessment by microcomputer.

An automated system for comprehensively monitoring glaucoma patients is described. This economic and practical microcomputer data system has been designed to be thoroughly 'clinician oriented' through the collaborative efforts of ophthalmological and computer specialists. It incorporates novel and efficient methods for transferring both automated and manually recorded perimetry data into analysable digital form. The system is inexpensive, simple to use, maintains safe records, allows thorough analysis of patient data, and can considerably reduce the administrative load on ophthalmological clinics.