A lens assembly of a viewing element for an endoscope has lenses and a barrel containing the lenses. The internal surface of the barrel is shaped in accordance with the relative position and size of the lenses and a lens holder encompassing at least a portion of the barrel. The barrel and/or the lens holder are injection-molded and can be variably positioned relative to each other. An optional adhesive layer that reduces or eliminates small particles from the viewing element is positioned on an inner surface of the barrel and/or lens holder and used to remove any internal particulate matter that may otherwise obstruct the field of view.