Scanning electron microscopy of deposits remaining in soft contact lens polishing marks after cleaning

Deposits are a complication of contact lens wear that have been associated with ocular diseases, including keratitis and giant papillary conjunctivitis. The purpose of this morphologic study was to describe the deposits on soft contact lenses fabricated by different surface manufacturing methods and to evaluate the ease of removal of deposits by surfactant cleaning. We studied the anterior surfaces of 30 soft contact lenses (10 lathe cut [polished]; 10 spin cast [unpolished], and 10 cast molded [unpolished]) of the same polymer and water content. All lenses were worn for 8 hours by two asymptomatic persons who did not routinely wear contact lenses. Lenses from one eye were immersed in glutaraldehyde, while lenses from the other eye were cleaned before immersion in glutaraldehyde. All lenses were then dehydrated in graded alcohols, critical-point-dried, and observed by scanning electron microscopy. The amount of deposit on the lens surface was judged by an individual who did not know the identity of the lens. All lenses showed similar types of deposits. At the end of 8 hours wear, all types of lens surfaces were covered with deposits. Cleaning removed some but not all deposits. The lens surfaces manufactured in such a way as to leave polishing or lathe marks showed deposits "heaped-up" on the marks before cleaning and remaining in the mark after cleaning. Polishing marks from lens fabrication may represent an increased risk for conjunctival insult from deposits remaining in the marks after cleaning.