Evaluation of contrast sensitivity function and optic nerve head in patients diagnosed with graves without orbitopathy

Purpose: The aim is to prevent irreversible vision loss in Graves' patients by enabling early diagnosis and appropriate follow-up methods during the subclinical stage before functional eye damage occurs. Material and Method: The study included 30 patients diagnosed with Graves' orbitopathy, 30 patients diagnosed with Graves' disease who did not develop orbitopathy, and 30 healthy volunteers. Comprehensive ophthalmological examinations were conducted for all three groups. Clinical activity was assessed using the clinical activity score, while disease severity was evaluated according to the European Group on Graves Orbitopathy classification. The spatial contrast sensitivity function of the participants was measured using the Functional Acuity Contrast Test (FACT) panel. Additionally, measurements were obtained from all participants using Spectral Domain Optical Coherence Tomography (SD-OCT), focusing on peripapillary retinal nerve fiber layer (RNFL) thickness and macular thickness across nine areas of the Early Treatment Diabetic Retinopathy Study (ETDRS) grid. OCT images were analyzed using the ImageJ software to calculate the choroidal vascular index (CVI). Results: No significant difference was observed when RNFL thickness, choroidal thickness, and CVI were compared between the groups (p>0.05). In the orbitopathy group, a decrease was noted in the spatial frequencies of 3 cpd, 6cpd, 12 cpd and 18 cpd (P<0.05). In the group without clinical orbitopathy, a decrease was noted in 12 cpd and 18 cpd spatial frequencies. This decrease was statistically significant (P<0.05). Starting from 6 cpd spatial frequency, contrast sensitivity values of the group with clinical orbitopathy and the group without orbitopathy became closer. However, the decrease in contrast sensitivity values was found to be more pronounced in the group with orbitopathy (P=0.011). At 12 cpd and 18 cpd spatial frequencies, contrast sensitivity values of the group with orbitopathy and the group without orbitopathy were similar, but both groups showed significantly lower values compared to the healthy population (P=0.005, P=0.001, respectively). vii Conclusion: Contrast sensitivity is diminished in patients with Graves' disease, both with and without orbitopathy. Notably, in patients without orbitopathy, contrast sensitivity testing may offer valuable supplementary information beyond standard visual acuity assessments, aiding in early diagnosis and monitoring. Keywords: Graves' disease, contrast sensitivity, choroidal vascular index, retina, thyroid orbitopathy