To compare the degrees of conjunctival injection and corneal toxicity between preservative and preservative-free topical 0.1% fluorometholone after strabismus surgery.

A randomized, prospective clinical study was performed to compare the degrees of conjunctival injection and corneal toxicity between preservative and preservative-free topical 0.1% fluorometholone after strabismus surgery. Sixty-one patients with intermittent exotropia were included in this study. They were told to apply antibiotic eye drops (ED) and either preservative or preservative-free topical 0.1% fluorometholone (F1) three times a day. Measurements of the degrees of conjunctival injection and corneal toxicity were performed at postoperative 1 week and 3 weeks each.

Seventeen patients (34 eyes) were included in group 1 (preservative F1) and twenty patients (40 eyes) were included in group 2 (preservative-free F1). The average pixel value (measured via the Image J software) representing the degree of conjunctival injection was 31,732 ± 9,946 in group 1 and 38,347 ± 12,189 in group 2 at postoperative 1 week, while the average pixel value was 10,150 ± 4,493 in group 1 and 11,836 ± 4,290 in group 2 at postoperative 3 weeks. There was a significant difference between the decrease in pixel value for the two groups ( p = 0.040). There was no significant difference in the mean value of the Oxford stain score between the two groups at postoperative 3 weeks, however the mean questionnaire scores in group 2 were significantly lower than in group 1 ( p = 0.001).

Preservative-free 0.1% fluorometholone ED demonstrated a larger decrease in the degree of conjunctival injection than for preservative ED after strabismus surgery. Therefore, the use of preservative-free steroid ED may be beneficial for decreasing both conjunctival injection and postoperative discomfort following strabismus surgery.