Stem Cell Deficiency in Patients with Chronic and Delayed-Onset Mustard Gas Keratopathy

To evaluate stem cell deficiency using impression cytology (IC) in patients with chronic and delayed-onset mustard gas keratopathy (MGK). A consecutive series of patients with MGK underwent IC. Thirty-five eyes of 18 patients (all male) with mustard gas keratopathy were included in this observational case series. Presence of goblet cells on the corneal side of specimens was considered to indicate stem cell deficiency. Corneal involvement was graded as mild, moderate and severe. Relation between IC findings and clinical grading was evaluated. There was limbal stem cell deficiency in at least one quadrant of the cornea in all 35 eyes (100% of cases). No differences was found between impression cytology findings (positive versus negative for corneal goblet cells) among different quadrants (p= 0.378). Clinical grading was the same between nasal and temporal quadrants (P=0.266) and between superior and inferior quadrants (P= 0.263). Combining the superior and inferior quadrants (vertical zone) and also the nasal and temporal quadrants (horizontal zone) together, clinical grading was more severe in horizontal versus vertical zones (p< 0.001). There was no correlation between stem cell deficiency and clinical corneal severity (p=0.893). Varying degrees of stem cell deficiency was demonstrated in all patients with chronic or delayed-onset MGK using IC. Clinical corneal manifestations are more severe in nasal and temporal quadrants. We found no correlation between stem cell deficiency and clinical manifestations. Other factors such as perilimbal conjunctival ischemia might play a role.