Background/Objectives: This study investigated the frequency and timing of optic neuritis (ON) episodes in relation to the onset of multiple sclerosis (MS) and examined the occurrence of Uhthoff’s phenomenon and Lhermitte’s sign to understand their roles in early diagnosis and disease progression. Methods: A longitudinal study was conducted with 127 MS patients. Clinical data, including ophthalmological examinations for ON, were collected and questionnaires assessed the presence of Uhthoff’s phenomenon and Lhermitte’s sign. Results: Results showed that 37% of patients experienced demyelinating retrobulbar ON, with 25.53% having ON as the initial symptom of MS. Residual visual acuity impairment (below 20/40) and dyschromatopsia were reported by 25.53% and 17.02% of patients, respectively. Uhthoff’s phenomenon and Lhermitte’s sign were present in 26.77% and 36.22% of patients, respectively. The findings underscore the importance of early ophthalmological assessments in diagnosing MS, as ON can be an initial indicator of the disease. Conclusions: The study highlights the need for precise diagnostic tools and personalized therapeutic strategies focused on specific biomarkers and pathways involved in neuroinflammation and demyelination. Early diagnosis through vigilant ophthalmologic evaluation can lead to interventions that significantly alter disease progression, improving patient outcomes and quality of life.
