Comparative Clinicopathological Evaluation of the Ocular Surface in Newly Diagnosed Patients of Hyperthyroidism and Hypothyroidism Compared to Healthy Subjects.

Introduction Thyroid eye disease is a multifactorial disorder affecting the tear film and ocular surface, which leads to dry eye. The aim of the study is to evaluate the tear function test and ocular surface changes clinically and to correlate pathologically using impression cytology in recently diagnosed cases of thyroid dysfunction, including both hyperthyroid and hypothyroid patients, and to compare the results with healthy subjects. Methods This was a cross-sectional analytical study. Thirty diagnosed patients with hyperthyroidism and hypothyroidism, each within three months, and 30 healthy age-matched controls were included. All patients and controls underwent an assessment of proptosis, palpebral fissure height (PFH), tear function test, Ocular Surface Disease Index (OSDI) questionnaire, Schirmer's test, tear break-up time (TBUT), and impression cytology for ocular surface assessment. These parameters were compared between cases and controls. Standard statistical analysis was used. Results Mean proptosis and PFH showed no significant difference among groups (P-value = .071). The mean value of OSDI was 42.33+22.67, 41.15+16.03, and 29.33+6.84 in the hyperthyroid, hypothyroid, and controls groups, respectively; the difference being statistically significant (p=0.001). Mean TBUT was 7.13+3.28 sec, 6.38+2.46 sec, and 11.15+2.39 sec in hyperthyroidism, hypothyroidism, and controls, respectively (p=0.001). The mean value of the Schirmer tear test was 12.93+5.81 mm, 13.30+4.44 mm, and 17.55+7.35 mm in hyperthyroidism, hypothyroidism, and controls, respectively (p=0.001). Eighty percent (80%) of patients in the hyperthyroidism group had grade 2-3 squamous metaplasia as compared to 70% in hypothyroidism patients and 24.4% in controls, signifying ocular surface damage (p<0.05). Conclusions The mean PFH and proptosis did not differ between the three groups. However, increased OSDI score, decreased Schirmer's test value, decreased TBUT, and grades 2-3 squamous metaplasia in patients with thyroid dysfunction suggest the presence of dry eyes. Despite no clinically visible signs of thyroid ophthalmopathy, there is ocular surface damage right from the early stages of thyroid dysfunction, possibly attributable to the evaporative mechanism as well as ocular surface inflammation and instability of the tear film.