How can you determine if a soft contact lens is inverted?

Determining if a soft contact lens is inverted can be reliably achieved by viewing the shape of the lens edge on your index finger. When the lens is placed on your finger and you look at the edge, an inverted lens will have a rounded edge that appears more convex, while a correctly oriented lens will have a flatter edge. This visual method allows for a quick and effective assessment of the lens orientation.

Other methods, while useful in different contexts, may not provide as definitive or clear an answer as checking the shape of the lens edge. For instance, inspecting the color of the lens may not be reliable, as the color can remain consistent regardless of orientation. Checking the thickness of the edges might also be misleading, since both inverted and correctly oriented lenses could present similar thickness characteristics. Additionally, holding the lens against a bright light may offer some visibility regarding any foreign particles or features but does not provide clear evidence of whether the lens is inverted. Thus, examining the lens's shape when viewed from the side is the most effective way to determine its orientation.