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Aims: To establish the sensitivity and reliability of objective image analysis in direct comparison with subjective grading of bulbar hyperaemia. Methods: Images of the same eyes were captured with a range of bulbar hyperaemia caused by vasodilation. The progression was recorded and 45 images extracted. The images were objectively analysed on 14 occasions using previously validated edge-detection and colour-extraction techniques. They were also graded by 14 eye-care practitioners (ECPs) and 14 non-clinicians (NCLs) using the Efron scale. Six ECPs repeated the grading on three separate occasions Results: Subjective grading was only able to differentiate images with differences in grade of 0.70-1.03 Efron units (sensitivity of 0.30-0.53), compared to 0.02-0.09 Efron units with objective techniques (sensitivity of 0.94-0.99). Significant differences were found between ECPs and individual repeats were also inconsistent (p,0.001). Objective analysis was 166 more reliable than subjective analysis. The NCLs used wider ranges of the scale but were more variable than ECPs, implying that training may have an effect on grading. Conclusions: Objective analysis may offer a new gold standard in anterior ocular examination, and should be developed further as a clinical research tool to allow more highly powered analysis, and to enhance the clinical monitoring of anterior eye disease.A ssessment of conjunctival hyperaemia is a vital part of any ophthalmic evaluation. The onset of hyperaemia can indicate not only ocular but also certain systemic conditions 1-3 and hence it is vital that the subtle variations in this surface are evaluated and monitored by clinicians as accurately as possible. The current best practice for such assessment is in the form of subjective grading scales that were introduced to reduce inconsistencies between examiners and to encourage uniform grading of the anterior eye.4-6 The level on the scale (commonly 4-5 predetermined images) that best matches the characteristic of the eye under observation is recorded, ideally to 1dp to improve discrimination. 7 However, these scales remain (by their nature) subjective and lead to inherently variable assessments, with a wide range of the scale utilised by different practitioners to describe the same image.5 8Practitioners also demonstrate a reluctance to interpolate between the grading images displayed, even if training has been undertaken. 9 This is compounded by the design of the scales themselves which are not linear in nature, instead having increased sensitivity at the lower end, although this is not always consistent. 8To improve this situation various studies have investigated computer-based objective grading of ocular surfaces. With respect to vascular changes, several parameters have been the focus of objective analysis software.10 11 Edge detection and colour extraction have been shown to be the most repeatable and discriminatory of those techniques, and have been found to be approximately 76 more reliable than that reported for subjective grading, 11 h...

The results indicate that clinicians may use a combination of vessel areas and overall hue in their judgment of clinical severity for certain conditions. Objective grading can take these aspects into account, and be used to predict an average "objective grade" to be used by a clinician in describing the anterior eye. These measures are more sensitive and reliable than subjective grading while still utilizing familiar terminology, and can be applied in research or practice to improve the detection, and monitoring of ocular surface changes.

Magnification can be provided to assist those with visual impairment to make the best use of remaining vision. Electronic transverse magnification of an object was first conceived for use in low vision in the late 1950s, but has developed slowly and is not extensively prescribed because of its relatively high cost and lack of portability. Electronic devices providing transverse magnification have been termed closed-circuit televisions (CCTVs) because of the direct cable link between the camera imaging system and monitor viewing system, but this description generally refers to surveillance devices and does not indicate the provision of features such as magnification and contrast enhancement. Therefore, the term Electronic Vision Enhancement Systems (EVES) is proposed to better distinguish and describe such devices. This paper reviews current knowledge on EVES for the visually impaired in terms of: classification; hardware and software (development of technology, magnification and field-of-view, contrast and image enhancement); user aspects (users and usage, reading speed and duration, and training); and potential future development of EVES.Keywords: closed-circuit television, electronic vision enhancement system, low vision, visual impairment Electronic Vision Enhancement SystemsThis paper reviews current knowledge on Electronic Vision Enhancement Systems (EVES) for the visually impaired. The initial section classifies EVES in terms of their camera, display and power supply characteristics. The second section examines Ôhardware and softwareÕ issues in terms of the development of EVES technology over the past three decades, magnification and field-ofview, contrast and image enhancement. The subsequent section investigates research conducted into ÔuserÕ aspects of EVES in the form of users and usage, reading speed and duration, and training. Finally, the last section discusses potential future development of EVES. EVES classificationThe broad range of EVES currently on the market has resulted from general consumer demand for the individual components (video cameras and display screens) and the simplicity of connecting them together. As a result, many of the companies selling EVES do not have a strong interest or background in low vision rehabilitation. Although attempts have been made to classify EVES in terms of performance attributes, such as portability, ease of operation and aesthetic appearance (Strong and Byard, 1992), these are difficult to quantify objectively. Uslan et al. (1996) described a classification for EVES available at that time in the USA, in the form of two main types: those in which the camera and/or display are mounted on a stand and those that use a handheld camera. The stand-mounted systems were further subdivided into Ôin-lineÕ or Ôside-by-sideÕ configurations and the features of representative systems were listed (such as the provision of colour and magnification range). A similar classification of handheld systems was recorded, with system configuration divided into