Anatomy - Eyelid
Our eyes are probably the most important vital structures we have in our body. They discovered on the surface by a thin layer of skin and soft tissue called the eyelids. The eyelids serve multiple purposes including protecting the eyeball from injury, controlling the amount of light that enters the eye and also constantly lubricating the eyeball with tears secreted by the lacrimal gland during blinking. All these functions together help maintain the structural integrity of the eyeball and protect them from external influences.
From an anatomical point of view, the eyelid consists primarily of skin, underlying soft tissue also called a subcutaneous tissue and a thin layer of muscle called the orbicularis oculi. Under this muscle are other issues that divide the area into different planes. These are called septum and include the fibrous orbital septum and tarsi. In adds to to this, in order for the eyelids to open are lid retractors that help assist blinking. Finally, there also exists a small amount of fat tissue as well. The eyeball is covered by a thin layer of tissue called the conjunctiva.
Anatomy of the eyelid
The description above only offers a superficial overview of the anatomy of the eyelid. If one were to look at the eyelid in a more detailed manner, a sagittal section taken across the eyelid will offer a clear view of the various structures that form it. Of course, it must be borne in mind that the structures that are visualised depend on the plane at which the sections are taken.
As mentioned above, the tissues can be divided into planes by structures called the septum. The orbital septum differentiates the orbital tissue from the lid. Behind the septum are a number of different other structures, a knowledge of which is essential if surgery is to be performed. In particular, it is essential to identify the anterior and posterior lamellae. In essence, the anterior lamella consists of the skin and the orbicularis oculi muscle while the posterior lamella consists of the conjunctiva and the tarsus.
Let's take a look at the structures of the eyelid in a bit more detail.
|Skin categories||Skin color in unexposed area||Tanning history||Skin Sensitivity Value|
|never tans, always burns||pale or milky, white alabaster||develops red sunburn, painful swelling, skin peels||4-10|
|frequently tans, usually burns||very little brown, frequently freckles||usually burns, pink or red coloring appears, can gradually develop light brown tan||10-12|
|usually tans, frequently burns||light tan, brown or olive, distinctly pigmented||rarely burns, moderately rapid tanning response||11-14|
|always tans, rarely burns||brown, dark brown or black||rarely burns, very rapid tanning response||12-16|
Skin Lotion Facts / Skin Cancer Facts
- What should you consider when you are looking for sun screen protection?The definition of radiation is "The process in which energy is emitted from molecules and atoms owing to internal change." (from Webster's Dictionary)UVB cause "burn appearance" UVB is most prevalent on sunny days from 10:00 am to 2:00 p.m.
- The frequency range should cover 280 to 400 nanometers. The greatest concern lies between 290 and 360 nanometers. DNA damage does occur in the UVB spectrum.
- The sun protection factor (SPF) addresses the time it takes for your skin to burn. The number signifies, in general, period of time (minutes) that it takes the average Caucasian skin to burn with sun screen versus not wearing one.
- There are several shortcomings of the "SPF System".A suntan lotion can offer 99% UVB protection and minimal UVA absorbency, yet it is classified as "broad spectrum" in the United States.
- There is a significant variance between products using "similar SPF"
- SPF only relates UVB and has nothing to do with UVA radiation; UVA radiation causes "aging appearance." UVA exists in rain or shine from sunrise to sunset 365 days a year.
- UVA causes long term damage that could not appear for years
- UVB and UVA radiation are both know to cause skin cancer.
- Because SPF rating does not acknowledge the specific amount of absorption in the UVB range and the FDA does not have a monograph for UVA production. There is no definitive measure in the United States to assess the efficacy of a suntan product for UVA and UVB production
- Did you know that several sunscreens break down within hours and must be reapplied often?
- Recent medical studies have proven that products utilizing Avobenzone (Parsol 1789) degrade and lose their ability to block further radiation. This degradation occurs upon exposure to sunlight! Other studies have demonstrated that a chemical reaction can occur with the active Methoxycinnamate ingredient destroying it and leaving users susceptible to large UVB exposure.