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The purpose of this study was to establish the extent of variability in the visual fields of patients with glaucoma using a suprathreshold perimetric test strategy. The visual fields of 104 patients (126 eyes) were measured twice, on separate days, with a Henson CFA3000 central visual field analyser. All eyes had a diagnosis of glaucoma and had a minimum of three stimuli missed at 12 dB above their threshold estimate derived at the beginning of the first suprathreshold examination. The perimeter tested 132 locations within the central 25 degrees with a multiple stimulus suprathreshold strategy. Data were analysed on the basis of the difference in the number of recorded missed stimuli between the two visits. Large amounts of variability were found in the visual field results. Variability was largest when all levels of defect were included (> = 5 dB) and was found to be independent of the overall extent of loss. Results from the superior hemifield were found to be more variable than those from the inferior hemifield. The results highlight the problem of differentiating real change in visual field status from the enhanced variability seen in patients with glaucomatous visual field loss. The results from this study can be used to establish return-referral criteria for shared care schemes. The advantages of duplicate measures of the visual field are highlighted.

The purpose of this study was the evaluation of community based optometric monitoring of stable glaucoma patients and glaucoma suspects compared to the routine Hospital Eye Services (HES) monitoring. Four hundred and five subjects were recruited from routine outpatient clinics at the Bristol Eye Hospital. All eligible participants were seen in the routine hospital clinic and then within two months were given a 'Gold Standard Assessment' (GSA) by an independent research team. Participants then visited one of 12 glaucoma-trained optometrists, for a standard battery of tests. Randomisation resulted in 204 subjects being allocated to community care, with reviews on a six monthly basis, with 201 who remained a control group within the hospital. Referral criteria were established to enable optometric detection of apparent glaucomatous progression. A questionnaire was used to assess patient satisfaction with both care types. Additionally a cost analysis exercise was performed.

Glaucoma patients are currently undergoing monitoring by community based optometrists as part of a randomised controlled trial of shared care. As part of this trial, the costs of monitoring these patients by community optometrists are being calculated. Data were obtained from eight practices for the 1993-1994 financial year. The average 'full' cost of a 40 min appointment was calculated as epsilon 31.56 pounds. The average number of unbooked appointments for the month of October 1994 was 16 per practice, which equated to 12, 40 min appointments. Once the number of unbooked appointments was surpassed for each practice, an average opportunity cost of epsilon 54.00 pounds was experienced per appointment. The participating optometrists were willing to accept a minimum fee of epsilon 26.03 pounds for a small number of patient assessments but this rose to epsilon 43.16 pounds for up to 100 glaucoma patients seen per annum.

Measurement of human lens biometry directly from Scheimpflug images of the anterior ocular segment may be impossible when pupil size precludes an adequate Scheimpflug view of the posterior lens surface. The authors describe a simple and accurate geometric method of overcoming this problem by estimating the true lens thickness from pairs of on-axis and off-axis Scheimpflug images. The method is validated and the variability of the estimate is quantified. This new method has utility in the study of lens biometry in subjects with large lenses whose pupils cannot be adequately dilated.