In conclusion, the available evidence suggests that patients with glaucoma often have an abnormal pupil response to illumination. The measurement of pupil response to light provides an objective test of visual function, which identifies a substantial portion of those with glaucoma in some studies. However, there is insufficient evidence from population-based research assessing pupil response under controlled conditions to support wider use of this approach. Also, an RAPD is relatively nonspecific and may be caused by a number of conditions other than glaucoma. Future studies investigating conditions and confounders affecting pupil responses and methods improving the accuracy of glaucoma detection would be useful.
The results reported should be interpreted in the context of study limitations. First, there are many factors other than glaucoma that may affect pupil response. Systemic or topical medications, previous ocular surgery, or the presence of an irregular pupil shape may limit the accuracy of the device. We tested the device in a controlled population and excluded subjects taking medications that were likely to affect the pupil response and those with significant comorbidities such as nonglaucomatous optic neuropathies and retinal disease. In clinical practice, the performance of the pupillograph therefore may be different. If the device were to be used in a setting such as community screening, it is likely that the specificity for detecting glaucoma would be lower because many conditions can affect pupil response. Further testing also would be needed to determine the cause of pupil response abnormality.
Although the relationship between disease severity and diagnostic ability of the best-performing full-field pupil response parameters did not reach statistical significance, it is possible that other pupil response parameters may be more affected by disease severity. We did not evaluate the effect of disease severity on the performance of every pupil response parameter because many had poor AUCs.
In conclusion, the pupil response parameters evaluated in this study had moderate ability to distinguish healthy subjects from those with glaucoma. The performance of the pupillograph depended on the characteristics of the population being tested and was significantly worse in those with more symmetric disease.