Contact Lens Product

مجهول
تم تعديل 2009/09/11 في علم الأدوية

There are 3 basic types of contact lenses : soft ,hard & rigid gas permeable (RGP) contact lenses .

A) HARD CONTACT LENSES :

these are made of a rigid hydrophobic plastic material , polymethyl methacrylate (PMMA) .
they are 7-10 mm in diameter & are designed to cover only part of the cornea .
they have low water content (0.5)

Advantages of hard contact lenses :

a) durable
b) provide clear vision
c) easily handled during insertion & removal
d) not absor drug which may be concomitantly applied to the eye
f) they are less liable to microbial contaminantion



Disadvantages of hard contact lenses :

a) require a long adaptation period for wearing comfort ( may reach up to one week )
b) they are impermible to oxygen which affects corneal epithelial respiration & patients comfort
c) they must be weeted with wetting solution to prevent physical damage of the corneal epithelium
d) they may allow irritating foreign particles such as dust to lodge bebeath them



SOFT CONTACT LENSEs
These made of a flexable hydrophilic plastic material , hydroxyethyle(HEMA)
they are 13-15 mm in diameter & cover the intire cornea
they have high water content (30-80%)

soft contact lenses have 3 types
:
A) daily-wear soft lenses : must be removed at night before the wearer goes to sleep .
B) extended-wear soft lenses : are designed to be worn for more than 24 hour . however , they shouldnot be retained in the eye for longer than 4 to 7 days without removal for cleaning & disinfection to avoid eye infwction
C) disposable soft lenses : they are worn for a certain period of time after which they are discarded & replaced with a new pair they should not worn for longer than recommended to avoid eye infection
Advantage of soft contact lenses ;
a) require a shorter adaptation period
b) they are permeable to oxygen , so more comfortable to the patient
c) they donot require wetting solution before wearing
d) they donot dislodge or fall out of the eye
e) they donot allow foreign particles to lodge beneth them



Disadvantages of soft contact lenses :

they are less durable than hard lenses
they donot provide the high level of clear vision as hard lenses
they may absorb medications applied to eye
their moist porous surface provides an attractive medium for microbial growth



RIGID GAS PERMEABLE CONTACT LENSES
(
RGP
)
These are made of a rigid hydrophobic but oxygen permeable plastic material ,cellulose acetate buturate ( CAB)
They have the same diminsions as hard contact lenses
They have all the advantage of hard lenses in addition to the oxygen permeability & patient comfort of the soft lenses
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to be continued

باقى جزئيه مهمه وهى كيفيه الاعتناء بالعدسات الاصقه والمحاليل اللازمه للحفاظ عليها ,وان شاء الله هعرض ف موضوعى القادم ايه المحاليل دى وايه اهميتها

التعليقات

  • dr.joandr.joan عضو ماسي
    تم تعديل 2009/09/10
    عن جد سارة المواضيع يلي عم تضيفها عم تغني المنتدى ...بالنسبة لموضوع العدسات أرجو في الفقرات الاحقة أن تحدثينا عن دور العدسات الاصقة في نقل الجرائيم و الإلتهابات في حال عدم الإعتناء بها بشكل جيد كي نبين للزاشر الكريم أهمية العناية بها بشكل جيد ...

    شـكــ وبارك الله فيك ـــرا لك ... لك مني أجمل تحية .
  • Dr.AhmadDr.Ahmad مدير عام
    تم تعديل 2009/09/11
    شكرا دكتورة سارة على الموضوع المهم جدا جدا

    - بس عفوا شو تأثير الاوكسجين على القرنية ؟؟؟ هل هناك من تأثير ؟؟؟

    في ناحية مهمة بالنسبة للعدسات هو موضوع التعرض للحرارة قد يؤدي لفقد البصر اذا كانت العدسة موضوعة و في عدة حوادث حصلت و للأسف
  • مجهول
    تم تعديل 2009/09/11
    they are impermible to oxygen which affects corneal epithelial respiration & patients comfort

    المقصود بيها ان العدسات دى بتكون غير نافذه او عازله للاكسجين اللى هو مهم لتنفس خلايا القرنيه وكمان راحه المريض
  • Dr.AhmadDr.Ahmad مدير عام
    تم تعديل 2009/09/11
    شكرا دكتورة سارة
سجل دخولكاو سجل حسابا للتعليق.