Optimized Method for Obtaining DNA from Used Contact Lenses – NEAFS Abstract

In many cases, DNA samples are collected from areas where a donor contacted an object in their environment and transferred biological material. One such object would be a person’s contact lenses, which could provide a clean singular sample of the contacts’ owner’s DNA. The purpose of this experiment therefore is to optimize extraction of nuclear DNA from used contact lenses taking into consideration different collection methods, various periods of time between collection and extraction, and incubation in different solutions. A volunteer wore contact lenses for approximately 12-14 hours, then placed the lenses in a mock crime scene for 24 hours. The lenses were then collected in a sterile manner and processed in various solutions and incubation times, followed by analysis of DNA quantity, quality and STR profiles. The results showed that DNA extraction was optimal from contact lenses stored in centrifuge tubes for 24 hours when the buffers used for incubation prior to extraction were either ATL or ATL/TE. These samples produced sufficient DNA yields to generate full STR profiles. However, samples that had long storage time and/or were stored in paper envelopes produced less DNA quantity, impacting the downstream analysis of STRs. This data provides guidance as to optimal extraction methods for contact lens material that have been left in storage or at a scene, adding this type of sample to the list of evidence that can be collected from crime scenes and provide suitable DNA profiles for the investigation.