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Glaucoma Dialogue IGR 15-2

Response

Comment by Davin Johnson & Delan Jinapriya & Hussein Hollands on:

53737 Do findings on routine examination identify patients at risk for primary open-angle glaucoma? The rational clinical examination systematic review, Hollands H; Johnson D; Hollands S et al., JAMA (Journal of the American Medical Association), 2013; 309: 2035-2042

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We thank our colleagues for their comments and insights in regards to our recent meta-analysis of glaucoma risk factors. The diversity of opinions reflects the complexity associated with population-based screening for glaucoma. As our article was written in the Rational Clinical Exam Series, the target audience was generalist physicians. However, all studies used in the meta-analysis occurred in an ophthalmologic setting, and the results of our study can be accurately applied in the ophthalmologic setting.

As commentator 2 noted, we grouped all cases of glaucoma together in our meta-analysis rather than sub-dividing by disease severity. This was partially to simplify the study for our target audience, but also due to the fact that studies rarely reported data sub-divided by disease severity. It is an interesting point as to what effect separating statistics by disease severity would have on likelihood ratios for glaucoma risk factors. As noted, it is perhaps less important for generalist physicians to identify early cases of glaucoma as it is to identify advanced cases where prompt therapy may delay or even prevent the progression to blindness. A study evaluating whether generalist physicians can identify patients with moderate or advanced glaucoma would be interesting and have important implications given that glaucoma remains a leading cause of blindness worldwide.

As commentator 3 noted, it is important to stress to all generalist physicians (and optometrists) that the absence of risk factors or certain examination findings does not rule out glaucoma. This is especially important for readers that do not know how to interpret likelihood ratios, and further strengthens recommendations by the AAO that all patients should have periodic eye examinations to monitor for ocular disease including glaucoma.

We hope that quantifying likelihood ratios of glaucoma risk factors based on a large meta-analysis of population based studies will provide assistance to both ophthalmologists and generalist physicians alike. While our overall data shows that isolated findings or risk factors are either not sensitive or not specific enough on their own to effectively screen for glaucoma, single findings (ex. cup-to-disc 0.9 or high IOP) still significantly increase the likelihood of glaucoma. We also recognize that screening for glaucoma is a complex process, given the significant diversity worldwide in terms of access to eye care, severity of disease, and other factors. While our recommendation is generally that patients be followed by an ophthalmologist rather than generalist physician to screen for disease, there are many circumstances where this is not practical.

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