Sambandet mellan okorrigerad vertikal heterofori och huvudvärkssjukdomar: Ett kliniskt perspektiv

Background: Vertical heterophoria is a form of binocular vision dysfunction associated with symptoms of headache and asthenopia. Headache disorders, including migraine, are highly prevalent worldwide. Although vertical heterophoria and migraine present with overlapping symptoms, such as headache, visual strain and dizziness, vertical heterophoria is not routinely screened in patients presenting with headache disorders in optometry clinics. Despite the clinical overlap, research exploring the association between these conditions remains limited. Aim: The aim of this thesis was to investigate whether subtle vertical heterophoria is underdiagnosed among individuals with headache disorders. To that end, we estimated the frequency, magnitude, and associated symptoms of vertical heterophoria in individuals with headache disorders compared to a headache-free control group. Method: In this case-control study, individuals with migraine and/or frequent headache (N = 32) were examined for vertical heterophoria and compared with a control group (N = 17). All participants underwent assessments of vertical dissociated and vertical associated phoria using standard clinical procedures. Symptoms profiles were evaluated using the Binocular Vision Dysfunction Questionnaire (BVDQ) and Symptom Severity Index (SSI). Results: The case group demonstrated a higher proportion (p < 0.001) and larger median value (p < 0.001) of vertical associated phoria (i.e. fixation disparity) compared with control group. However, no statistically significant differences were found between the groups regarding dissociated phoria tests. The case group also had significantly higher median scores on the BVDQ (p < 0.001) and the SSI (p < 0.001) compared with controls. Multiple regression analysis revealed a clear association between group affiliation and symptom severity for both BVDQ (p = 0.002) and SSI (p < 0.001) but no significant relationship with presence of vertical associated heterophoria. Conclusion: The findings suggest that vertical associated heterophoria is more prevalent among individuals with headache disorders and highlights the importance of including screening for vertical heterophoria in the evaluation of patients with headache and migraine.