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Glaucoma screening by optometrists: positive predictive value of visual field testing.
D K Newman1, S Anwar, K Jordan
1Department of Ophthalmology, West Suffolk Hospital, UK.
Eye (London, England)
|May 18, 1999
Summary
Visual field testing by optometrists for glaucoma detection has a low positive predictive value (PPV), leading to unnecessary referrals. Adhering to validated screening methods is crucial for accurate glaucoma diagnosis.
Area of Science:
- Ophthalmology
- Optometry
- Diagnostic Accuracy
Background:
- Glaucoma detection is a key area for optometrists.
- Visual field testing is a common tool used in practice.
Purpose of the Study:
- To evaluate the positive predictive value (PPV) of visual field testing as performed by optometrists for glaucoma detection.
- To determine if current practices improve the accuracy of glaucoma suspect referrals.
Main Methods:
- Retrospective analysis of 86 referrals for suspected glaucoma to an ophthalmology department.
- PPV calculation based on referral reasons and subsequent glaucoma diagnosis.
Main Results:
- Isolated visual field loss referrals (12%) showed no glaucoma detection (PPV 0%).
- PPV was significantly lower for isolated field loss compared to referrals with additional abnormalities (0% vs. 60%).
- No significant PPV difference for referrals with raised intraocular pressure or suspicious discs.
Conclusions:
- Current visual field testing practices by optometrists result in unnecessary referrals.
- There is no detectable improvement in the accuracy of glaucoma suspect referrals.
- Optometrists should adopt validated screening methodologies for visual field testing.