Glaucoma detection in the community: does ongoing training of optometrists have a lasting effect?

PURPOSE: To establish whether the effect of improved glaucoma detection in the community suggested by an intervention study is maintained when intervention is extended to include all optometrists in the area. METHODS: Optometrists' in the Ealing, Hammersmith, and Hounslow area were invited to ongoing training sessions following completion of an intervention study. The number of optometrist initiated referrals to Ealing Hospital Eye Clinic (EHEC) for suspect glaucoma was assessed over a 12-month period. The positive predictive value (PPV) of those referrals was calculated and a historical comparison made with the results of the original study. RESULTS: A total of 376 new referrals for suspected glaucoma were assessed at EHEC during the 12-month period of data collection. This represents an increase in the number of referrals of 58% compared with an equivalent 12-month period during the initial intervention trial (376 vs. 238). The PPV was maintained at 0.45 (95% CI 0.41-0.51). CONCLUSION: The rising number of new referrals for glaucoma together with maintenance of the PPV suggests an impact on the number of new cases of glaucoma detected in the community. The increase in referral numbers was limited to glaucoma when compared with new referrals for cataract. This implies a targeted effect of the intervention in terms of glaucoma detection. We believe the next step is to perform the study in an alternative location to see if the effect is repeatable elsewhere. If proven to be the case, there is a coherent argument for widespread adoption of this strategy to improve glaucoma case finding.

Glaucoma case finding: a cluster-randomised intervention trial.

PURPOSE: To assess the effect of an intervention comprising training in optic disc assessment, explicit referral criteria and ophthalmologist feedback on referred patients, on the number of optometrist referrals for suspected glaucoma seen at a referral site and the positive predictive value of those referrals. METHODS: Optometric practices routinely referring to the Ealing Hospital Eye Clinic were randomly divided into two groups taking into consideration those practices, which shared an optometrist (a cluster) and the number of optometrist days worked per week. One group of practices acted as controls, while the other practices were invited to receive the intervention. Data on 397 new patients referred and presenting to Ealing Hospital with suspected glaucoma were collected over a 20-month period. The data on patients who had failed to attend their appointment were collected over 7 months of this period. The number of referrals seen, the positive predictive value of those referrals, and the attendance rate were calculated. Optometrist's opinions of the intervention were assessed qualitatively. Data relating to optometrist compliance with the intervention were also collected. RESULTS: The number of glaucoma referrals presenting to Ealing Hospital from the intervention practices was almost double that from the control practices (210 vs 119). When cluster randomisation, the number of optometrist days per cluster and the number of assessed referrals in the preintervention period are taken into consideration, it is estimated that the intervention is associated with a 52% increase in the number of referrals reaching Ealing Hospital. However, the design effect resulting from the cluster randomisation was unexpectedly high (of the order of 13-14)and so the confidence intervals around the estimate of 52% are very wide (95% c.i. 35% decrease to 253% increase, P = 0.34). There was no evidence of an association between optometrist compliance with the intervention and the number of referrals seen at Ealing Hospital. The positive predictive value (PPV)of referrals was similar for the intervention(0.49 (95% c.i. 0.42, 0.55)) and control groups(0.46 (95% c.i. 0.33, 0.60)). Optometrist opinions of the intervention were largely favourable. All expressed a willingness to participate in future programmes. CONCLUSION: A large difference in the number of referrals between the practice groups was observed. Since the PPV of referral was unchanged, the potential impact of the intervention in terms of numbers of new cases of glaucoma detected in the community is substantial. However, because of its large design effect, this trial does not provide conclusive evidence of an impact of the intervention on referral numbers. A considerably larger trial will be required to produce conclusive evidence of an effect.

Sensitivity and specificity of two glaucoma case-finding strategies for optometrists.

Current best practice for primary open-angle glaucoma case-finding comprises history-taking, disc examination, intraocular pressure measurement and suprathreshold visual field analysis (SVFA). An alternative case-finding technique was formulated replacing SVFA with computerised quantitative disc assessment, using the Heidelberg retinal tomograph II (HRT II). Each approach was adopted by four optometrists who screened 29 POAG and 37 normal patients. Average sensitivities and specificities were similar in the two groups [sensitivity 71% (SVFA) vs 69% (HRT II); specificity 94% both groups]. Our inclusion of pre-perimetric glaucoma cases limited the sensitivity of the optometrists in this study. There was evidence to suggest that the optometrists tended to miss early changes at the optic disc such as disc haemorrhage, nerve fibre layer defects and subtle neuroretinal thinning.

What optic disc parameters are most accurately assessed using the direct ophthalmoscope?

PURPOSE: It has been suggested that over-reliance on the cup-to-disc ratio is a major factor in the misinterpretation of the optic disc. In spite of this optometrist assessment of the optic disc tends to be restricted to measurement of the cup-to-disc ratio and cup depth only. Would interpretation of the disc improve if optometrists were to evaluate other parameters? The aim of this study was to evaluate the accuracy of optometrist assessment of nine parameters of the optic nerve head using direct ophthalmoscopy. METHODS: Eight optometrists evaluated nine parameters of the optic nerve head (vertical disc diameter, vertical cup-to-disc ratio, neuroretinal rim configuration, cup shape, neuroretinal rim colour, vessel path, presence/ absence of haemorrhage, extent and location of peripapillary atrophy and classification of health status of the disc) in 50 eyes of 50 patients using direct ophthalmoscopy. Intensive training in optic nerve head assessment was given prior to assessing the patients. Criteria for evaluation were discussed. The 'gold standard' reference was the classification of the parameters by a consultant ophthalmologist with a special interest in glaucoma. RESULTS: Interobserver agreement for vertical cup-to-disc ratio was almost perfect (mean weighted kappa 0.84). Agreement for neuroretinal rim configuration, cup shape, haemorrhage and final classification of the disc was good (mean kappa 0.62-0.67). There was moderate agreement for vessel configuration (mean kappa 0.53). For assessment of peripapillary atrophy, disc size and neuroretinal rim colour, agreement was fair (mean kappa 0.22-0.34). CONCLUSIONS: Accuracy of assessment was greatest for vertical cup-to-disc ratio, neuroretinal rim configuration and cup shape. Improved agreement has been demonstrated for the final classification of the disc compared with previous reports. The combination of training and assessment of additional disc parameters appears to improve interpretation of the optic nerve head by optometrists.

Positive predictive value of optometrist-initiated referrals for glaucoma.

A study was conducted at the Moorfields Community Eye Clinic at Ealing Hospital to determine the positive predictive value (ppv) of optometric referrals for suspected glaucoma. The information reported in the referrals and the reasons given for referral were also assessed and evaluated in relation to the ppv. Information was gathered through prospective analysis of patient clinic notes. Ninety patients were referred over a six-month period of which 87 fulfilled the inclusion criteria. The optometrist referral letters for 79 of these patients were supplied by the GP. Results indicate a ppv of 0.43. The reason for referral in the majority of cases (48%) was raised IOP alone. However the most frequently reported mode of practice was a combination of disc and IOP assessment (57%). In line with other research our study demonstrates that referral accuracy improves as the number of suspicious findings increases. In addition those referrals reporting all three tests (IOP measurement, optic disc assessment and perimetry) are shown to have the highest ppv.