医学课件：接触镜的特殊应用2

1、Special contact lens,Wenzhou medical college School of optometry,Bandage lenses,Cornea epithelial As a therapeutic modality Require overnight wear,Underlying mechanism,Mechanical protection of the disrupted or healing epithelium from the environment Structural reinforcement and promotion of healing

2、of a weakened area, such as a small perforation or a descemetocele Relief from pain, especially in cases of bullous keratopathy,PRK,LASIK,High water bandage lens,CooperVision Perfilcon A (71%) Bullous keratopathy, diffuse punctate epithelial keratopathy,Medium water bandage lens,CIBA Softcon EW Func

3、tion as splint Minimal lens movement is desired Wound dehiscence(separation of sutured wound margins) Descemetocele Small corneal perforation Large nonhealing epithelial defect,Drug carrier contact lens,Increase the time of releasing drug Keep high concentration of drug Contact lens water content Th

4、ickness of contact lens,Tint contact lens,For cosmetology For special therapy aim,Tint contact lens,amblyopia achromatopsia(color blindness) albinism ( artificial pupil ) double vision,Contact Lenses and Keratoconus,Contact Lenses and Keratoconus,Non-inflammatory, usually bilateral Onset usually dur

5、ing second decade of life Disease will progress over period of 7 to 20 years Prevalence fairly equally divided between men and women,“An ocular disorder characterized by progressive corneal thinning (ectasia) and other sequelae”,Contact Lenses and Keratoconus,Corneal tissue change Biochemical collag

6、en disorder Atopic etiology Allergy related disorders Heredity Dominant / recessive trait,“An ocular disorder characterized by progressive corneal thinning (ectasia) and other sequelae”,Contact Lenses and Keratoconus,Systemic disorders Downs syndrome / Marfans Contact lens wear (unilateral) Long tim

7、e PMMA lens wear Poorly-fitted rigid lenses Low ocular rigidity,“An ocular disorder characterized by progressive corneal thinning (ectasia) and other sequelae”,Contact Lenses and Keratoconus,Cornea assumes irregular conical shape,Etiology,Irregular astigmatism develops Progresses at variable rate Ma

8、y require surgical intervention,Contact Lenses and Keratoconus,Superior and peripheral cornea remains relatively normal,Corneal Topography,Inferior cornea steepens Central cornea steepens,Assumes oblique/ATR astig.,Contact Lenses and Keratoconus,Corneal Topography is essential to confirm diagnosis,

9、follow, and and manage the condition,Corneal Topography,Contact Lenses and Keratoconus,MildKs of 52.00D,Classification by Keratometry Readings,Contact Lenses and Keratoconus,Classification by Cone Shape,Nipple 6 mm - More diffuse, larger size,Classification by Cone Size,圆锥侧面,Fleishers Ring,Vogts str

10、iae,corneal scarring.,Munsons Sign,Placido ring,Contact Lenses and Keratoconus,VA fully corrected with spectacles Some increase in refractive astigmatism Normal keratometry readings with very little (if any) keratometry mire distortion Not easy to diagnose.topography very helpful to establish baseli

11、ne,Classification by Stage,Stage One,Contact Lenses and Keratoconus,K reading range - 45.00 to 50.00 D with 1 - 4D corneal steepening Notable increase in refractive astigmatism Definite corneal distortion,Classification by Stage,Stage Two,Fleischers Ring may be present,Complaints of “ghosting” / mon

12、ocular diplopia,Contact Lenses and Keratoconus,K reading range - 50.00 to 55.00 D (5-10D corneal steepening) Spectacle VA decreased Irregular refractive astigmatism of 2.00 to 8.00D,Classification by Stage,Stage Three,Corneal thinning evident,Keratometry mire distortion makes taking “K” readings dif

13、ficult,Contact Lenses and Keratoconus,Increased corneal surface distortion,Striae,Pronounced cone shape with corneal thinning,Contact Lenses and Keratoconus,K readings greater than range 55.00 D Stage Three signs intensify,Classification by Stage,Stage Four,Munsons Sign present,Apical scarring,Placi

14、do环,Case #1,Female 35yrs Blur with right eye for 1yr Uncorrected VA： OD：0.25 OS:1.0 Auto-Ref:-2.25/-6.25*168 -0.50/-2.50*176 Sub-Ref:-2.25 =0.8 -0.25/-0.50*40 =1.0,Auto-Ref:-2.25/-6.25*168 -0.50/-2.50*176 Sub-Ref:-2.25 =0.8 -0.25/-0.50*40 =1.0,Case #2,Male 16yrs Blur with both eyes for 8yrs monocula

15、r diplopia（OS） Auto-Ref:-6.50/-3.75*1 -6.50/-1.75*176 Sub-Ref:-5.50/-1.50*15 =0.7 -5.50/-0.75*155=0.8,Contact Lenses and Keratoconus,Large diameter, semi scleral / scleral lenses,Contact Lens Modalities,Soft contact lenses Gas permeable contact lenses “Piggyback” / combination lens fitting,Contact L

16、enses and Keratoconus,Rigid Lens Designs,Spherical Aspheric (3-point touch) Soper Cone (apical vaulting) Scleral,Rose K for Keratoconus,Maximal tear exchange under lens,Contact Lenses and Keratoconus,Systematic approach to KC fitting Fit can be adjusted as condition advances,Easy to fit Highly repro

17、ducible,Contact Lenses and Keratoconus,Start with 8.7 mm diameter (standard) Select Base Curve Ave K Achieve 3-point (feather) touch,Rose K for Keratoconus,Contact Lenses and Keratoconus,Rose K for Keratoconus,Rose K Standard fit,Standard spherical GP lens fit,Contact Lenses and Keratoconus,Rose K f

18、or Keratoconus,Standard spherical GP lens fit,Rose K Standard fit,Contact Lenses and Keratoconus,“Piggyback” or dual lens system SoftPerm Flexlens,Other Lens Design Options,Piggyback Lenses,Hybrid lens,SoftPerm: Dk 14 SoftPerm2: Dk 100,Contact Lenses and Keratoconus,Manufactured using digital CAD-CAM technology Utilize new high permeability GP materials (85 to 100 Dk) Excellent where corneal lenses cannot be worn,Scleral Lens,What is old becomes new again”,Contact Lenses and Keratoconus,Affordability