Intrinsic aging affects both sun-exposed and non-sun-exposed
skin and is characterized by dryness, laxity, skin atrophy,
and fine wrinkles.

Histologically, one may see a thin epidermis with an intact
stratum corneum, resulting in prominence of vasculature
leading to transparency of the skin. Others are flattening
of dermoepidermal junction, a decrease in dermal thickness,
diminished dermal vascularity, and a decreased ability
of dermal fibroblasts to produce collagen, manifested
as increased time for wound healing.

Intrinsic aging is genetically mediated predominantly.
Other factors which contributed may be the natural effects
of gravity, expression lines, sleep lines, and hormonal
changes.

Histologically, photodamage can cause an increase or a
decrease in epidermal thickness corresponding to areas
of irregular contour and atypia of keratinocytes corresponding
to rough solar keratoses. UV light causes degeneration
of collagen and deposition of altered elastic tissue predominant
as wrinkles and yellow discoloration of skin in the dermis
and on microcirculation is manifested in telangiectasias.

Collagen breakdown which is due to induction of metalloproteinases
mediates the damaging effect of UV exposure. This pathway
can be inhibited with pretreatment by retinoids .Photodamaged
skin leads to reduction in precursors of both collagen1
and 3 types. Solar elastosis, a blue colored staining
material which histologically mimics elastin is seen in
severely photodamaged skin.

Collagen and elastin fibre is mainly due to edema of endothelial
cells and connective tissue, recruitment of inflammatory
cells, which release cytokines and other growth factors
leading to collagen remodeling. Formation of collagen
in dermis is histologically confirmed following the laser
treatment. Collagen remodeling continues for a period
of 6-12 months.

Nonablative photo rejuvenation(improvement in sun damage
and aging skin) uses two main targets, discrete chromophores(oxyhemoglobin
and melanin) in the dermis(intense pulse light laser IPL)
or the dermo-epidermal junction and mid infra red wave
lengths to target tissue water(neodymium:yttrium-aluminium-garnet
ND:YAG). Deep penetration and scattering of light is achieved
with relative long wave length, mild water absorption
and poor oxyhemoglobin and melanin absorption. Results
are gradual and progressive and multiple treatment sessions
are required with both approaches.

1540nm Er:Glass laser is also used in periorbital and
perioral wrinkles. There is an increase in thickness in
dermis by 17%.

Fractional photothermolysis (reliant lasers) is a new
technology and new treatment protocol that targets only
a small fraction of skin surface like the pixel in a digital
photograph and treats photo damaged skin. It is mainly
used in dyschromias including melasma, acne and other
scars, and photo-damaged skin of chest, face, neck and
hands.

Retinol and Retinoids

A common ingredient found in antiaging creams.Retinol
represents the main dietary source transport and storage
form of vit A .Retinoids consists vit A and belongs to
a family of structurally and functionally related compounds.It
is (vit A) obtained through dietary meat and cannot be
synthesized in body.It is converted in body to its biological
active form all trans-retinoic acid(tretinoin) through
an intermediate product retinaldehyde.Tretinoin is 24
times more effective than retinol and the cutaneous concentration
of tretinoin is 1000 fold less with topically applied
retinoid than with tretinoin. Interaction with specific
nuclear receptors is controlled at the cellular level
by trans-retinoic acid.UV radiation causes significant
reduction in collagen formation due to upregulation of
metalloproteinases such as collagenases and gellatinases,
decrease in precollagen synthesis and due to intrinsic
aging process.Pretreatment with tretinoin reduces all
these. Tretinoin use leads to both clinical and histological
improvement of photodamaged skin. Use of tretinoin shows
a dose dependent improvement in fine wrinkling, mottled
pigmentation and laxity.

Increase in epidermal thickness (granular layer), compaction
of stratum corneum, increase in epidermal and dermal mucin,
decrease in melanin content, improvement in the structure
of the dermo-epidermal junction and improvement in keratinocytes
ultra structure has been noted histologically. Tazarotene
(newer topical retinoids) is also as effective as tretinoin
in reducing moderate pigmentation and fine winkling of
photoaging skin.

They cause smooth appearance of skin as a result of their
keratolytic activity, resulting in reduces adhesion of
keratinocytes and increased turnover of stratum corneum.

They include glycolic, lactic, citric, pyruvic, malic
and tartaric acid.

Use of these agents for antiaging purpose has been a boom
recently. Lactic and Glycolic acid are commonly used.

They increased epidermal thickness; glycosaminoglycans
increase epidermal skin firmness as measured by ultrasonography
without any accompanying dermal change.

Increased acid mucopolysaccharides, improved quality of
elastic fibers and increased density of collagen were
also noted Histologically.

According to some studies TGF-beta can increase collagen
synthesis, promote granulation tissue formation, increase
the size of regenerated dermis, and stabilize the dermoepidermal
junction. There is an improvement in skin texture ,wrinkle
depth and texture as measured by optical profilometry.
Increase in epidermal thickness and grenz collagen was
demonstrated histologically.

In general, when using those agents that each have a mild
to modest efficacy, expectations need to be realistic.

However, it is our impression that far greater success
is achieved by the use of a program that not only combines
multiple cosmeceutical agents but also takes advantage
of the distinct benefits of the nonablative lasers and
ablative procedures.