OCT Findings and Ocular Changes in Subclinical Hypothyroidism

Objective: To evaluate the changes in intraocular pressure (IOP), central corneal thickness (CCT), retinal nerve fiber layer thickness (RNFLT), foveal thickness (FT) and choroid thickness (ChT) in patients with subclinical hypothyroidism.
Methods: Sixty eyes of 30 patients with subclinical hypothyroidism (study group) and 60 eyes of 30 healthy subjects (control group) were included in the study. A complete ocular examination including best corrected visual acuity (BCVA), IOP, anterior and posterior segment examination together with CCT, RNFLT, FT and ChT measurements were performed in each group. p<0.05 was accepted statistically significant.
Results: Global (G) RNFLT, nasal (N) RNFLT, nasal inferior (NI) RNFLT and ChT (p=0.008, p=0.006, p=0.046 and p=<0.001 respectively) values of the study group were statistically higher than the control group. There was a weak negative correlation between ChT and RNFLT temporal inferior (TI) and nasal (N) and global (G) quadrants in the study group (r=-0.426; p=0.024, r=-0.403; p=0.034 & r=-0.410; p=0.030 respectively). FT values of the control group were statistically higher than the study group (p=0.026).
Conclusions: Glucosaminoglycan accumulation in subclinical hypothyroid group may cause increase in RNFLT(G) and ChT. According to the SD-OCT (Spectral Domain - Optical Coherence Tomography) measurements of subclinical hypothyroid patients, negative correlation between ChT and RNFLT may be a guide in terms of progression to glaucoma. Besides, FT measurement follow-up, which may be inversely proportional with the level of hypothyroidism, may lead off about the level of visual acuity (VA). In addition to all these, the ChT may be a guide in following the treatment process. The results of our study should be supported by further studies.