Astigmatism
A flat piece of glass. Also, any lens where the shape of the convex part matches the shape of the concave part. An example would be a flat piece of glass bent over a sphere.
irregularities
of Irregularity
Any polygon must have at least three sides. So a shape with only one pair of adjacent sides must be lenticular (shaped like a lens) else it is some very odd shape.
I do not think there is any shape that you would come across normally. One shape that I can think of is a bi-convex lens with a partial ridge. I am not entirely sure that the ridge counts as an edge, but that's my best offer.
a shape of a lens is curved outwards and concave one are curved in wards
A converging lens is also known as a magnifying lens. The shape of the lens is a double convex shape.
The testes should be free from lumps, pain, irregularities and swelling.
the lens of our eyes is different to the lens of a magnifying glass-it can change its shape from thick to thin
The role of a lens is to converge and or diverge light depending on the shape of the lens.
A lenticular shape: the shape of a lens.
NO
A concave circle
Rectangle
Your are mixing properties. Converging lens is always thicker in the centre and thinner at the edges. The other cathegory is the geometry of shape of the surfaces of the lens. Convex means that the shape is similar to the outer surbace of a sphere, concave means that the shape is similar to the iner surface of a sphere (or: convex = lower side of a spoon as we use it for sampling a soup; concave: upper (inner) shape of the spoon). A double convex lens is always a converging lens. A plano-concave lens is always a diverging (not converging) lens. A convexo-concave lens is the most usual shape of a lense used in spectacles. It can be either converging or diverging, depending on the radii of the surfaces.
The lens of the eye also called the crystalline lens.
it is lens in shape