Evaluation of the Corneal Endothelial Cell Layer by Specular Microscopy in Patients With Thyroid Eye Disease

Thyroid eye disease is a common periorbital autoimmune inflammatory disease .It significantly impairs quality of the life ,causes cosmetic defects ,and could be sight-threatening ,especially when optic nerve or the cornea is affected.Classic manifestations of thyroid eye disease include proptosis ,lid retraction ,lagophthalmos,optic neuropathy and restrictive extraocular myopathy.In addition to the affection of the orbital and lacrimal glands ,the corneal endothelium has showen morphological changes in patients with thyroid eye disease .corneal endothelium is the innermost corneal layer facing the anterior chamber and is known for maintaining corneal transparency by its pump-leak function .corneal transparency is crucial for optimal vision . severe damage to corneal endothelium can induce corneal opacification .resulting in corneal edema and subsequently vision loss. That is because there are thyroxine receptors in all layers of the conea. And the autoantibodies to TSH receptors usually attach to them causing damage to the cornea.Specular microscopy is one of the best investigative procedure used to assess changes in the corneal endothelium due to thyroid eye disease.Specular microscopy is a noninvasive photographic technique that analyze the corneal endothelium. Using computer-assisted morphometry, modern specular microscopes analyze the characteristics of the endothelial cells. The instrument projects light onto the cornea and captures the image that is reflected from the optical interface between the corneal endothelium and the aqueous humor. The reflected image is analyzed by the instrument and displayed as a specular photomicrograph