Hydrogels and silicone hydrogels

Hydrogels and silicone hydrogels

1. HYDROGELS & SILICONE HYDROGELS WHEN AND WHY?? Churawan Lal Sahu M Optom 1 Churwan Lal Sahu M Optom

2. HYDROGELS & SILICONE HYDROGELS Hydrogels-Advantages Offers good initial comfort Less Prone to displacement Offers Good Centration Stabilize promptly after insertion Churwan Lal Sahu M Optom 2

3. HYDROGELS & SILICONE HYDROGELS Hydrogels-Disadvantages Poor oxygen transmission More dryness Greater care and maintenance Limited parameters available Churwan Lal Sahu M Optom 3

4. HYDROGELS & SILICONE HYDROGELS Hydrogels-Disadvantages Lens handling can be difficult Uptake of preservatives May discolour with topical medications Churwan Lal Sahu M Optom 4

5. HYDROGELS & SILICONE HYDROGELS Hydrogels-Indications Who rarely uses CL Who uses CL only for 6-8hours Who are concerned about Money Churwan Lal Sahu M Optom 5

6. HYDROGELS & SILICONE HYDROGELS How does the cornea get its O2 if it doesn’t have blood vessels? Cornea – Avascular Structure O2 required – Principally from the atmosphere Reduced oxygen supply can result in changes to the epithelium, stroma and endothelium Churwan Lal Sahu M Optom 6

7. HYDROGELS & SILICONE HYDROGELS What happens if the eyes don’t get enough oxygen? Red Eye Polymegathism Hypoxia Neovascularisation Corneal Edema Churwan Lal Sahu M Optom 7

8. HYDROGELS & SILICONE HYDROGELS What happens if the eyes don’t get enough oxygen? More prone to deposits Dehydration Inflammation Infections in Extended Wear Churwan Lal Sahu M Optom 8

9. HYDROGELS & SILICONE HYDROGELS Why isn’t DK/t 24 always enough? Patients experience increased oxygen need resulting from environment conditions( Altitude, dryness ) Churwan Lal Sahu M Optom 9

10. HYDROGELS & SILICONE HYDROGELS Churwan Lal Sahu M Optom 10 Long wearing days More contact lens users nap in their lenses:84% !

11. HYDROGELS & SILICONE HYDROGELS Requirements for healthy wear Oxygen transmissibility DW – Dk /t > 35 Oxygen transmissibility EW– Dk /t > 125 Low modulus Surface wettability Resistant to dehydration Biocompatibility Churwan Lal Sahu M Optom 11

12. HYDROGELS & SILICONE HYDROGELS Why silicone hydrogels ? Churwan Lal Sahu M Optom 12

13. HYDROGELS & SILICONE HYDROGELS Churwan Lal Sahu M Optom 13 Silicone Hydrogels High DK Hydrophilic Highly oxygen Permeable , wettable material

14. HYDROGELS & SILICONE HYDROGELS Silicone hydrogels : Advantages More healthier than conventional SCL Increased oxygen transmission More resistance to protein deposits Less dehydration Lower risk of infection Lower incidence of complication with EW Churwan Lal Sahu M Optom 14

15. HYDROGELS & SILICONE HYDROGELS Silicone hydrogels : Indications High prescriptions Wearers who experience end of day discomfort/dryness/redness Wearing hours>12-14hrs Whose eye requires more oxygen Who work long hours in low humidity/air conditioning Churwan Lal Sahu M Optom 15

16. HYDROGELS & SILICONE HYDROGELS Silicone Hydrogels:Properties 1.Oxygen Transmissibility Churwan Lal Sahu M Optom 16

17. HYDROGELS & SILICONE HYDROGELS 2.More Comfort Churwan Lal Sahu M Optom 17

18. HYDROGELS & SILICONE HYDROGELS 3.Increased rigidity Easily handle Corneal astigmatism is masked Churwan Lal Sahu M Optom 18

19. HYDROGELS & SILICONE HYDROGELS 4.Surface wettability Contact Angle (CA) -Ability of a fluid to spread over a contact lens surface CA more wettable the surface Higher Wettability More comfort Churwan Lal Sahu M Optom 19

20. HYDROGELS & SILICONE HYDROGELS Silicone Hydrogels:Disadvantages More expensive Attract lipid deposits Blurred vision/Discomfort Rigid material Adaptation Issues Churwan Lal Sahu M Optom 20

21. HYDROGELS & SILICONE HYDROGELS HYDROGEL Combination of polymer&water - soft with limited oxygen Redness around cornea if worn longer than recommended Limited wearing hours SILICONE HYDROGEL Combination of silicone,polymer&water - soft ,5-6 times more o2 than hydrogels Healthier ,whiter eye even if worn longer Long wearing hours Churwan Lal Sahu M Optom 21

22. HYDROGELS & SILICONE HYDROGELS More water content,more dryness at the end of the day More protein deposits-compromised comfort Difficulty during handling Less dryness (low water content Less protein deposits-More comfort Very good handling due to shape factor Churwan Lal Sahu M Optom 22 HYDROGEL SILICONE HYDROGEL

23. THANK YOU 23 Churwan Lal Sahu M Optom