Evaluation of Patterns and Correlations of the Degree of Conjunctival Hyperemia Induced by Omidenepag Isopropyl 0.002% and Ripasudil 0.4%

Purpose: To evaluate the pattern of conjunctival hyperemia induced by omidenepag isopropyl 0.002% and ripasudil 0.4%, and its correlation with the degree of hyperemia. Subjects and Methods: We previously reported the time course of conjunctival hyperemia induced by administering one drop of omidenepag isopropyl to one eye and one drop of ripasudil to the other eye in 34 healthy subjects (mean age: 29.7 years; 22 females, 12 males). We assessed the degree of hyperemia by slit-lamp photography of the frontal and temporal conjunctiva 0, 15, 30, 60, 120, 180, and 360 min after the administration of one drop of omidenepag isopropyl and ripasudil. The data were used to compare the frontal photographs before and at the peak of hyperemia according to the clinical hyperemia score (0-3) and classify the pattern of developing hyperemia due to both drugs. We also examined the correlation between the degree of hyperemia by comparing the images captured at the peak of hyperemia in both groups, using clinical hyperemia score and “percent coverage” of conjunctival hyperemia by using an automated hyperemia analysis software program; this program provides the pixel coverage of the conjunctival vessels in the region of interest. Results: There were significant differences in the developmental pattern of hyperemia between omidenepag isopropyl-administered and ripasudil-administered eyes (P<0.001, χ(2) test), with dilation of large blood vessels only (N=2 vs. 1, respectively), small blood vessels only (N=17 vs. 5), both large and small blood vessels (N=8 vs. 27), and no change (N=6 vs. 0). The degree of hyperemia between the two groups was positively correlated with the hyperemia score (rs=0.344, P=0.055) in the frontal conjunctival photographs and the percent coverage of conjunctival blood vessels (r=0.510, P=0.003) in the temporal conjunctival photographs. Conclusions: The pattern of conjunctival hyperemia induced by omidenepag isopropyl predominantly involved small blood vessels, whereas that of ripasudil involved both large and small blood vessels. The eyes that were hyperemic with omidenepag isopropyl also tended to be hyperemic with ripasudil.