Contact lenses also known as contact lenses, not only in terms of appearance and ease of connection to the myopia and hyperopia and astigmatism, and other refractive errors brought in a lot of improvement, and broad vision, depending on realism, in addition to control young people myopia and astigmatism Development, the special treatment of eye disease, and other aspects have also played a special effect.
First, the classification of contact lenses
1, in accordance with the contact lens materials can be divided into rigid contact lenses and soft contact lenses (SCL). We normally have access to SCL.
2, according to wear contact lenses may be the time, can be divided into long-wearing type and discards (on the left-month-throwing, quarter-throwing, throwing six months of the year parabolic-type, etc.) contact lenses.
3, according to the role of contact lenses can be divided into therapeutic, beauty and so on.
Second, the types of contact lenses
Contact lenses now roughly divided into categories: high oxygen permeability rigid gas-permeable contact lenses (RGP) and the soft contact lens (SCL).
1, the soft contact lens (SCL)
Soft contact lenses can absorb moisture and oxygen penetration, soft and curved, to stimulate the cornea less, in line with the requirements of corneal respiratory metabolism and can be used for general myopia, hyperopia and astigmatism treatment, contact lenses are currently the mainstream products.
Benefits: The plasticity of a good, very comfortable to wear, to a short time. Since no need to repeatedly They are intermittent wear. Larger diameter, the lens, located on the edge of eyelid, the eyelid to avoid friction with the lens edge incurred by the foreign body sensation, and intraocular lenses will not swap out. Use of its soft, absorbent and the characteristics of large diameter, be used for the treatment of ocular surface diseases of use. Lens is attached to bear on the verge of corneoscleral margin, were not aware of, it looks beautiful. Tu can be stained or eye color for the beauty and orthopaedics.
Disadvantages: low-intensity material, easily damaged. Strong plastic lenses, corneal astigmatism correction less effective. - Polar surface, easy to tear absorption in the sediments, pathogenic microorganisms, and the composition of care, leading to eye complications, the cleansing, disinfection procedures require stringent, and to consider lens care products and compatibility. The vast majority of the wearer is not enough oxygen permeability of ideals, not overnight wear.
2, high oxygen permeability rigid gas-permeable contact lenses (RGP)
RGP with the SCL were all wearing the eye surface, the overall change in the eyes of refraction, to achieve the objective of refractive errors corrected.
Benefits: RGP has a good molding, not easy to deformation, high-quality optical correction, especially for a high degree of myopia and astigmatism in patients with a high degree of correction better. For various reasons the cornea irregular astigmatism (such as keratoconus, corneal refractive surgery, trauma surgery, etc.), RGP is the only effective method of improving vision correction, you can also control the disease’s development, play a role in the treatment .
RGP to wash, protein, fat little precipitation, nursing process is simple, low incidence of inflammation, high oxygen permeability, small diameter lens, the eye does not interfere with the normal metabolism, and the eyes have a better compatibility than SCL Safety, applicable to long-term wear contact lenses in patients with refractive errors.
Disadvantages: Because RGP is used without water to the special materials, texture hard, there will be initial wear mild foreign body sensation, the adaptation period than the SCL long engaged in intense sports, the stability of SCL not good to wear SCL less than comfortable, but also to be made from a variety of lens surfaces within the specifications of the bend, adapt to different eye wear, an increase of post-mortem with the technical difficulty, prices are more expensive.
3, corneal shaping mirror (Ortho-K CL, OK Mirror)
Is a special design of the RGP, through the cornea reasonable physical orthopaedics, can quickly reduce the degree of myopia, markedly improved, low myopia uncorrected visual acuity, so that patients remove glasses during the day. The most important thing is that it can effectively control myopia degree of growth, obviously, the exact effect, especially in the age of 18 following the rapid development of myopia young people with myopia, or some special professional needs.
It should be noted that, cornea-shaping of medical supplies, the need for post-mortem with high technology and a good supporting medical equipment, to be ophthalmologists or optometrists under the supervision and guidance of a doctor with a post-mortem. In addition, the wearing of the cornea after the change is irreversible, to maintain good therapeutic effect observed to be wearing a long time, in the course of the need to wear regular review.
Third, the important parameters of contact lenses
1, the water content - that contact lenses absorbent material saturated, water the percentage of the total weight.
Water content of soft lenses is an important parameter, so the lens is soft because of the aquifer, the water content of a number of decisions of the wearer. The higher the moisture content that the wearer relatively soft, but also relatively easy to deformation, because it dehydration dry sooner the contrary, the lower water content, relatively hard lenses, the deformation of small, easily dehydrated dry. Moisture can be divided into: low moisture content 38%, 42% moisture content to 60 percent, high moisture content> 60%.
High myopia lens thickness of the edge of its thick, the average oxygen permeability of the lens worse, it should be chosen high moisture content, high oxygen permeability of the lens. The dry eyes should choose to wear low water content of the lenses so that the lenses absorb only a small tear, leaving more humid corneal tear.
2,-arc - the lens surfaces within the centre-arc. - Arc longer than the wearer-Globoidal; shorter-arc, the wearer Globoidal than bend.
- Arc is the choice of law: it is not appropriate to-bear! The method can be used finger over the lens and cornea check with the degree of tightness. To wear those eyes, the check to a finger upwards push lower eyelid, that is used to promote progressive lenses under the lower eyelid margin, if the wearer in a push to fully slip from the cornea is too loose, if not the slightest move to a corner, some push from the As appropriate.
3, the center thickness - the thickness of the lens focal point.
Astigmatism with ordinary people spherical soft mirror, the thickness should be selected centres Shaohou lenses, the lenses may be too thin because of the shape of the cornea and change its shape, can not form the ideal lens.
4, oxygen permeability - contains oxygen permeability of the following parameters: Dk value (oxygen permeability coefficient Dk), Dk / L (oxygen conductivity), EOP (such as oxygen rate).
Dk values: oxygen through a certain degree of contact lenses. D-oxygen in the material in the diffusion coefficient, k-factor solution. The higher the moisture content, Dk a higher value.
Dk / L: oxygen through a certain thickness of the actual speed of a particular lens. L that thickness. , Wearing Dk / L> 24, wearing a long Dk / L> 87. Thickness of the thin, oxygen permeability of the better.
EOP: people living on the lens and cornea between the percentage of oxygen. EOP maximum 21 percent, on wearing EOP> 12%, long wearing EOP> 18%.
The oxygen permeability of different lenses larger difference. Generally speaking, the more thin lenses, the higher the water content, the higher the rate of oxygen permeability, of course, this is not absolute. In fact, the moisture content above 50% will lead to the wearer easily damaged and deformed, easy adhesion proteins, such as sediments, generally used only for the parabolic-type lenses; On the contrary, the lower the moisture content can be extended lens exchange for life And reduce sediment attachment, can be used to do six months left, the parabolic-type contact lenses.
If the cornea in the metabolic state of hypoxia, the passage of time will lead to complications, so to avoid sleep wear contact lenses.
5, refractive index - light in the air and the speed of light in the material in the speed ratio. The refractive index of the material
Fourth, wear contact lenses and maintenance of Attention
1, confirmed the wearer about the pros and cons before wearing;
2, and if so will stimulate the sense of the wearer to remove check for dust or hair Xu;
3, please do not open the lid at the same time, so as not to swap around lid;
4, wearing glasses, to make up; lenses unloaded only when the facial Xiezhuang;
5, wearing a fingertip finger can not be too much moisture, or when wearing lenses with fingers easy adhesion, hard-Ruyan;
6, fully Bakai from top to bottom eyelid so that the lenses have enough space Ruyan.
7, if in the process of wearing lenses can not Ruyan, not eager to once again wear glasses, but should be washed after wearing glasses full.
8, before the use of care depends on a certain statement.
9, wear contact lenses or won before we must clean hands;
10, a nail can not be too long or too sharp, to avoid contact lenses to other sharp things.
11, a day when we must clean the lens with their hands Cuoxi lenses;
12, different brands of contact lens care solution can not be used interchangeably;
13, the regular replacement of the preservation of boxes of contact lenses, the best time for three months;
14, contact lens care solution can not be re-opened three months after use;
15, if not often wear contact lenses, should also be separated for a day of care;
16, the lens can not be placed on saline water preservation;
17, eye irritation, redness, must bring down.
5, the first to wear contact lenses Notice
Initial wear contact lenses, eye will be more or less accompanied by some of the symptoms are not suited. Therefore, the initial wear contact lenses should be gradually extended wear time. The first day of 2-4 hours, a day after the extension of two hours, up to more than 12 hours; stopped wearing more than two weeks of wear are also early implementation of the recommendations of the Dai Dai time. Even customary wear contact lenses, also recommends wearing a day in about eight hours each week 1,2 days to switch to eyeglasses, this is conducive to the long-term eye health.
If the initial wear contact lenses to dry a bit of sense, photophobia, as nearly fuzzy short-term, foreign body sensation, depending on zoom in or out, as long as the plot is not serious, the shorter the duration, which is a normal physiological reflect. After the general after a short adjustment period, the symptoms will disappear naturally, the specific needs of adaptation period and the quality of lenses and the ability to adapt to the individual concerned, normally a few hours to several days. If wearing a week after the symptoms continue or even increase, should immediately remove the lens and went to the post-mortem with the division or detailed examination of the eye care, find out the reasons.
Initial wear contact lenses are careful not to care as Run of the use of eye drops. To use the Run-eye drops, we must first consulting a doctor or pharmacy personnel are applicable to the use of wearing contact lenses.
