1. C.L is placed on the cornea, which can be compared to the glass of a watch.
2. C.L. are made up of special plastic and these don't break easily unlike glasses.
3. Cornea normally takes up oxygen from the atmosphere (breathes!), which is partly interfered by C.L., which is dependent upon the permeability of the particular C.L to oxygen.
4. Conjunctival sac is a closed cavity hence C.L can not get lost after slipping from corneal surface or go inside eye.
5. For higher powers, say more than 3 D, C.L. have other advantages besides cosmetic purposes. Unlike specs, C.L. do not lead to image minification and peripheral field restriction.
6. C.L. are of 3 types – Hard , semisoft (gas permeable, G.P.) and soft depending upon stiffness of the lens. Semisoft C.L. are actually hard but behave like soft C.L. in allowing greater oxygen permeability.
7. Hard C.L. is not permeable to oxygen unlike soft & semisoft (G.P.) lenses & are no more used.
8. C.L could be either daily wear (DW) (for usage during waking period only) or extended wear (EW) for overnight usage also.
9. By definition, extended wear lenses can be worn for more than 24 hours without removal, but in Indian climate it is advisable to use them as daily wear lenses only.
10. Disposable C.L (are always soft only).- Unlike conventional C.L., these are to be discarded at a planned interval on daily/weekly/fortnightly/monthly or 3-monthly basis. With these, one can avoid deposits on C.L., infections are less likely & one gets clearer vision every time one uses a brand new lens. These are now available in cylindrical powers also.
11. Two varieties of solutions are available for use with the contact lenses
(i) Different purpose solutions (are now no more used) is set of 3 solutions
for 3 different purposes.
(a) Cleaning solution - for cleaning the lens like a soap.
(b) Rinsing solution - which is saline for soft C.L. and tap water for
semisoft C.L.
(c) Soaking Solution - for overnight storage of C.L. (also simultaneously disinfects).
(ii) Multipurpose Solution - acts as cleaning, rinsing as well as soaking agent.
12. Soft C.L. unlike semisoft don't pop out even with sudden jerky movements of head and playing etc.
13. Adaptation of eye to C.L. takes approx. 2 wks, which is longer for semisoft and shorter for soft C.L. Slight watering, irritation and redness are common during this period.
14. Before inserting C.L., always ensure that it is not everted (i.e. upside down).
15. Enzyme cleaning of C.L. is done every 2 weeks or more depending upon the quality of tears of each individual. Enzyme cleaning indirectly also prevents infection and prolongs the life of C.L.
16. Enzyme cleaning is not required with most brands of solutions now available.
17. Regular C.L. wearer should preferably keep one day off (say on Sunday) for C.L. and use glasses on that day.
18. Don't insert the C.L. while standing near wash basin as it is quite a common cause of loosing the C.L.
19. To lift the dropped C.L. use any finger wet with multipurpose solution.
20. Make-up should be applied only after insertion of C.L.
21. Soft C.L. may be used as and when required while semi-soft C.L. are to be used regularly and if restarted after gap of few days, it has to be started gradually only all over again.
22. Make it a habit to open right eye C.L. bottle first to avoid mix up of C.L. of different eyes with different powers or curvatures.
23. Soft lenses don't generally last for more than 1- 2 years after which they need to be changed. Disposable C.L. (changed every 2nd, 7th, 15th or 30th day with a new one) are also now available in India.
24. Coloured cosmetic C.L. (blue, green, grey, brown etc.) are also now available in various powers.
PRECAUTIONS WITH USE OF C.L
1. Always wash your hands and dry them before you handle the C.L.
2. Never bypass the cleaning process of C.L. every time you insert the C.L.
3. Soaking/Multipurpose (MPS) solution (i.e. solution for overnight storage of C.L.) must be changed daily.
4. Never store the soft and semisoft C.L. dry (Always keep in MPS/Soaking soln).
5. Never exceed wearing time (8-10 hrs. for daily wear C.L. and upto 24hrs. for extended wear C.L.
6. On starting C.L. wear for the first time, always increase the wearing time slowly over days (increase by 2hrs. per day to a maximum of 8-10 hrs.
7. Never touch tap water with soft C.L.
8. Never sleep with C.L. on.
9. Swimming and bathing with C.L. on is not permitted.
10. Don't rub the eyes with C.L. on.
11. Clean C.L. container every week with soap/detergent and water.
12. Avoid wearing C.L. in dusty atmosphere or windstorm.
13. Avoid facing strong winds/ air with C.L. on e.g., sitting directly before cooler, A.C./ using hair dryer, sitting near the door in a moving vehicle.
14. Don't use any eye drops with contact lenses on. Minimum period of half an hour should be there before you insert the C.L. after putting the eye drop.
15. Any undue redness, watering, irritation, pain or blurring of vision must be reported to the doctor immediately.
16. Even if having no complaint with C.L., always visit your doctor at least once in 3 months.
17. Don't forget to carry a travel kit for wearing C.L. while going out of station.
18. Always store the C.L. with concave side up.