April 29, 2022
1 min read
Disclosures: The authors reported no relevant financial disclosures.
Functional and structural glaucoma severity was associated with impairment intrinsically photosensitive retinal ganglion cell function, according to a study published in Investigative Ophthalmology and Visual Science.
“The significant association between PIPR [postillumination pupil response] and glaucoma incision shown in our study was consistent with the findings of four previous clinical studies that revealed associations between impaired ipRGC [intrinsically photosensitive retinal ganglion cell] function and glaucomatous damage, such as RNFL [retinal nerve fiber layer] thinning and visual field defects,” Tadanobu Yoshikawa, MD, PhD, of Nara Medical University and Yoshikawa Eye Clinic in Japan, and colleagues wrote.
Yoshikawa and colleagues conducted a cross-sectional analysis of the LIGHT study, which included 148 patients with glaucoma, and assessed ipRGC function by PIPR using pupil diameter after exposure to blue and red light.
After adjusting for multiple variables, investigators determined that worsening in visual field mean deviation (MD) was associated with higher blue six-second PIPR amplitude, while thinner RNFL thickness was associated with higher blue six-second PIPR amplitude, lower net PIPR change and lower net PIPR.
Comparison of 35 patients with nonsevere glaucoma (mean age, 68 years; 37% men) and 113 patients with severe glaucoma (mean age, 71 years; 50% men) revealed that the severe glaucoma group had a significantly higher prevalence of oral medication use (antihistamines and dopaminergic drugs) and history of cataract surgery vs. the nonsevere group (P = .036 and .004, respectively). Initial pupil size during blue light stimulus in the severe glaucoma group also was larger than the nonsevere group (P = .015).
Further, analyzes of the visual field MD were inversely correlated with blue 6-second PIPR amplitude (P < .001) and positively correlated with net PIPR change (P = .044), while RNFL thickness was inversely correlated with blue 6-second PIPR amplitude (P < .001) and positively correlated with net PIPR change (P = .004) and net PIPR (P = .012).
“Our results indicate a possible circadian misalignment in patients with glaucoma through impairment ipRGC function,” the authors concluded.