In this case series, 19, 21, and 33 years old male patients who complain of blurred vision presented with corneal edema after using insulation material in the workplace. Isocyanate is a raw material used in the production of all polyurethane materials and is used as a basic material in construction and industrial products. We aimed to emphasize that corneal toxicity may be developed due to exposure to diphenylmethane diisocyanate and polymethy-lene polyphenyl isocyanate, which are used as insulation materials, and that both employees and ophthalmologists should take caution about this rare situation.