Comparison of pupil size in patients of migraine with photophobia versus normal subjects and correlation of the pupil size to severity of headache

Abstract

Purpose: To compare the pupil size of patients having migraine with photophobia versus normal subjects and to correlate the pupil size to the severity of headache. Methods: This was a prospective case–control study. One hundred eyes of 50 patients who had migraine with photophobia were compared with same number of control subjects who had no history of headache. Pupil size was measured using the IOL Master 700 in all cases. Severity of headache was evaluated by the Migraine Disability Assessment (MIDAS) test questionnaire, and MIDAS grades from 1 to 4 ranging from minimal disability to severe disability were obtained in all cases. The pupil sizes in all grades were compared. Results: The mean pupil size was 4.89 ± 0.9 mm (95% confidence interval [CI]) in patients of migraine with photophobia compared to 3.8 ± 0.49 mm (95% CI) in normal subjects, with a P value of <0.0001, which was statistically significant. Among the 50 patients with migraine, according to MIDAS grades, 20 had Grade 4 or severe disability, 15 had Grade 3 or moderate disability, 10 had Grade 2 or mild disability, and five had Grade 1 or minimal disability. Pupil size in Grade 4 category was the largest with a mean value of 5.6 ± 0.79 mm (95% CI). Conclusion: The pupil size in patients of migraine with photophobia is larger than in normal subjects and could be a trigger for the migraine attacks. The larger the pupil size, the more severe is the migraine disability.