Table 1.

Comparison of chronological aging and photoaging

Ageing types	Identification characteristics
	Epidermis	Dermis	Clinical
Chronological aging	Thinner than normal with lower cell growth, minor abnormalities in keratinocyte regularity Normal stratum corneum There is loss of rete pegs here as well	Elastin fibers appear irregular in their arrangement, whereas collagen fibers begin to lower in number and thickness	Skin is smooth, unblemished, but shows saggy appearance
Photoaging	Thick skin, with acanthosis followed by atrophy of the cells High basal keratinocyte irregularity Stratum corneum appears compact There is loss of rete pegs here as well	Excessive production of elastin fibers in an improper orientation, collagen fibres appear to thicken and then wear out soon Appearance of grenzzone	Smooth, leathery, reddened appearance with initially light wrinkles, which later deepen, thus showing loss of collagen fibers