Severity of reduced near point of convergence in patients with Parkinson’s disease: a cross-sectional study
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Abstract
Objective: To assess the severity of reduced near point of convergence (NPC), indicative of convergence insufficiency (CI), in patients with Parkinson's disease (PD).
Methods: This cross-sectional study was conducted on 80 patients with PD at Services Hospital, and Lahore General Hospital, Lahore, Pakistan from March to September 2024. Patients aged 40–70 years with a confirmed diagnosis based on the UK Parkinson's Disease Society Brain Bank criteria were included. Demographic and clinical data were collected using a structured investigator administered questionnaire. NPC was measured with a Royal Air Force ruler under standardized conditions. Patients with refractive errors of ≥5.00 DS and those with coexisting neurological or ocular disorders were excluded. Data were analyzed using SPSS version-25.0.
Results: The study included 42 males (52.5%) and 38 females (47.5%). Mean age was 55.90±8.33 years in males and 51.39±5.47 years in females. Mean disease duration was 2.33±1.44 years, while the mean NPC value was 19.94±3.97 cm. Based on NPC measurements, 35 patients (43.8%) had mild CI (10–18 cm), 35 (43.8%) had moderate CI (19–26 cm), and 10 (12.5%) had severe CI (27–34 cm). A statistically significant positive correlation was observed between disease duration and NPC values (r = 0.628, p < 0.001), indicating greater convergence impairment with longer disease duration.
Conclusion: Reduced NPC, consistent with convergence insufficiency, was universally present among patients with Parkinson's disease, with severity predominantly in the mild-to-moderate range. These findings highlight the importance of routine neuro-ophthalmic screening.
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