Glaucoma detection: the content of optometric eye examinations for a presbyopic patient of African racial descent.

AIMS: Standardised patient (SP) methodology is the gold standard for evaluating clinical practice. We investigated the content of optometric eyecare for an early presbyopic SP of African racial descent, an "at-risk" patient group for primary open-angle glaucoma (POAG). METHODS: A trained actor presented unannounced as a 44-year-old patient of African racial descent, complaining of recent near vision difficulties, to 100 community optometrists for an audio-recorded eye examination. The eye examinations were subsequently assessed via a checklist based on evidence-based POAG reviews, clinical guidelines and expert panel opinion. RESULTS: Ninety-five per cent of optometrists carried out optic disc assessment and tonometry, which conforms to the UK College of Optometrists' advice that those patients aged >40 years should receive at least two of the following tests: tonometry, optic disc assessment, visual field testing. Thirty-five per cent of optometrists carried out all of these tests and 6% advised the SP of increased POAG risk in those of African racial descent. CONCLUSION: SP encounters are an effective measure of optometric clinical practice. As in other healthcare disciplines, there are substantial differences between optometrists in the depth of their clinical investigations, challenging the concept of a "standard sight test". There is a need for continuing professional development (CPD) in glaucoma screening, in which the increased risk of POAG in those of African racial descent should be emphasised.

The Pattern Glare Test: a review and determination of normative values.

Pattern glare is characterised by symptoms of visual perceptual distortions and visual stress on viewing striped patterns. People with migraine or Meares-Irlen syndrome (visual stress) are especially prone to pattern glare. The literature on pattern glare is reviewed, and the goal of this study was to develop clinical norms for the Wilkins and Evans Pattern Glare Test. This comprises three test plates of square wave patterns of spatial frequency 0.5, 3 and 12 cycles per degree (cpd). Patients are shown the 0.5 cpd grating and the number of distortions that are reported in response to a list of questions is recorded. This is repeated for the other patterns. People who are prone to pattern glare experience visual perceptual distortions on viewing the 3 cpd grating, and pattern glare can be quantified as either the sum of distortions reported with the 3 cpd pattern or as the difference between the number of distortions with the 3 and 12 cpd gratings, the '3-12 cpd difference'. In study 1, 100 patients consulting an optometrist performed the Pattern Glare Test and the 95th percentile of responses was calculated as the limit of the normal range. The normal range for the number of distortions was found to be <4 on the 3 cpd grating and <2 for the 3-12 cpd difference. Pattern glare was similar in both genders but decreased with age. In study 2, 30 additional participants were given the test in the reverse of the usual testing order and were compared with a sub-group from study 1, matched for age and gender. Participants experienced more distortions with the 12 cpd grating if it was presented after the 3 cpd grating. However, the order did not influence the two key measures of pattern glare. In study 3, 30 further participants who reported a medical diagnosis of migraine were compared with a sub-group of the participants in study 1 who did not report migraine or frequent headaches, matched for age and gender. The migraine group reported more symptoms on viewing all gratings, particularly the 3 cpd grating. The only variable to be significantly different between the groups was the 3-12 cpd difference. In conclusion, people have an abnormal degree of pattern glare if they have a Pattern Glare Test score of >3 on the 3 cpd grating or a score of >1 on the 3-12 cpd difference. The literature suggests that these people are likely to have visual stress in everyday life and may therefore benefit from interventions designed to alleviate visual stress, such as precision tinted lenses.

Tinted spectacles and visually sensitive migraine.

A double-masked randomized controlled study with cross-over design compared the effectiveness of precision ophthalmic tints in the prevention of headache in migraine sufferers. Seventeen patients chose the colour of light that optimally reduced perceptual distortion of text and maximized clarity and comfort. They were later given glasses with spectral filters providing optimal colour under conventional white lighting ('optimal' tint) or glasses that provided a slightly different colour ('control' tint). The tints were supplied in random order, each for 6 weeks, separated by an interval of at least 2 weeks with no tints. Headache diaries showed that the frequency of headaches was marginally lower when the 'optimal' tint was worn, compared with the 'control'. The trial extends to adults with migraine, the results of a previous double-masked study demonstrating, in children with reading difficulty, beneficial effects of precision tints in reducing symptom frequency. In the present study, however, the effects are suggestive rather than conclusive.

Optometric function in visually sensitive migraine before and after treatment with tinted spectacles.

Optometrists frequently encounter patients with migraine and patients and practitioners sometimes suspect that visual stimuli or visual anomalies trigger headaches. There is a lack of evidence-based research on the issue, however. Some patients with migraine may be hypersensitive to visual stimuli, and it has been suggested that individually prescribed coloured filters might be an effective treatment to reduce symptoms from such stimuli. A recent randomised controlled trial showed such a treatment to be effective and the present paper reports on the optometric characteristics of the patients in this study. Twenty-one patients with neurologically diagnosed migraine were compared with 11 controls. No significant differences were found between the two groups with respect to refractive error, ocular pathology, colour vision, contrast sensitivity, accommodative function, strabismus and hyperphoria. The migraine group tended to be a little more exophoric, but by most criteria they were able to compensate for their exophoria as well as the control group. The migraine group were more prone to pattern glare than the controls (p = 0.004). The effects of precision tinted and control tinted lenses were investigated. The only variable to show a consistent and marked improvement with tinted lenses was pattern glare. The most likely mechanism for the benefit from individually prescribed coloured filters in migraine is the alleviation of cortical hyperexcitability (Wilkins et al. 1994) and associated pattern glare.