Thyroid function, diabetes, and common age-related eye diseases – a Mendelian randomization study

Previous Mendelian randomization (MR) studies showed an association between hypothyroidism and cataract and between high-normal free thyroxine (FT4) and late age-related macular degeneration (AMD), but not between FT4, thyroid stimulating hormone (TSH), or hyperthyroidism and diabetic retinopathy or cataract. These studies included a limited number of genetic variants for thyroid function and did not: investigate autoimmune thyroid disease (AITD) or glaucoma, include bidirectional and multivariable MR, examine sex differences or potential mediation effects of diabetes. We aimed to address this knowledge gap.