Skin Ageing and Sun: What happens in Photoaging?

The skin is affected by intrinsic and extrinsic factors, which causes it to lose its structural integrity and its normal physiological function, becoming older. Older skin is characterised by thinness, laxity, wrinkles and dyspigmentation. At Clinica London our consultant dermatologist Dr Jennifer Crawley will be pleased to advise you on how you can reduce the environmental influences on your skin ageing.
The external factors or extrinsic factors that cause extrinsic ageing include

• sunlight exposure
• cigarette smoking
• air pollution
• sleep deprivation

Most literature up to now has focused on UV light exposure and cigarette smoking as constant extrinsic causes that accelerated skin ageing and has focused our action on pharmacological prevention and treatment of such changes.
Sun exposure causes photoaging, which is a histological and clinical consequence of chronic ultraviolet light exposure. Kligman and Kligman devised the term photoaging in 1986 to distinguish this particular type of skin ageing from the intrinsic or chronological skin ageing that comes with time and genetic predisposition. Photoaging causes disorganisation of collagen fibrils in the connective skin tissue and the accumulation of abnormal amorphous elastin containing material making a condition called actinic elastosis. Actinic elastosis can occur on the surface of the eye as pinguecula and pterygium and in the skin as part of photoaging.
In photoaged skin, mature collagen fibres are replaced with collagen with a different appearance called basophilic degeneration. Unfortunately, the changes induced by chronic sun exposure occur deep within the skin well before they are seen visibly and clinically and before the signs of intrinsic or genetic skin ageing is seen. The typical clinical features of photoaging include deep wrinkles on the forehead and static frown lines even without facial motion. Furthermore, little red vascular spots called telangiectasia across the nose, cheeks and chin and a leathery skin which is quite lax with solar lentigines which are large blotchy freckles and actinic keratoses which can be dry, scaly patches. The most prominent clinical features of photoaging in the epidermis are the pigmentary changes with hyperpigmentation which are essentially irreversible, but can be visibly reduced and eliminated, but will recur once the treatment to reduce them and sunscreen block is stopped.
In my next blog, I shall talk about the environmental influences of smoking on the skin.