医学课件：接触镜的并发症和处理

1、1,Complications ofContact Lens Wear,School of Optometry need high mag or special instrumentation Specular microscope,95,Treatment,Change to higher Dk or RGP Monitor for further cellular changes, corneal edema,96,Complications of CL wear,Eyelids and conjunctiva Tear film Corneal epithelium Corneal st

2、roma Corneal endothelium Corneal shape change,97,Corneal shape change,Mechanical pressure on the cornea by lens or eyelids Corneal edema induced by contact lenses Mucous adherence under the rigid lens,98,Corneal shape change,Overall corneal curvature change SAI and SRI change of corneal topography C

3、orneal warpage,99,Definition of a deposit:, any lens surface coating or matrix formation which is not flushed or rinsed from a lens by tears during blinking,100,CONTACT LENS DEPOSITS,Care and maintenance procedures reduces deposits But cant eliminate them,101,Factors influencing lens deposition,Indi

4、vidual difference in tear Lens material Care system Wearing schedule Enviroment Patient hygiene,102,DEPOSIT SUSCEPTIBILITY:SCL MATERIALS,Generally Low water materials deposit less than high water materials Non-ionic materials deposit less than ionic materials,103,DEPOSIT SUSCEPTIBILITY:RGP MATERIALS

5、,Deposits form on lens surface only Reasons: No water to permeate lens Small pore size (limited polymer-free space),104,CONSEQUENCES OF DEPOSITACCUMULATION,Problems that can be caused by deposits: Decrease in: Vision Comfort Wearing time Lens wettability Lens Life Ocular reactions,105,PROTEIN DEPOSI

6、TS,A semi-opaque or translucent film Usually thin,whitish and superficial Cover lens surface partially or fully Consist of denature lysozyme Cause the lens surface to become hydrophobic Can crack and peel if thick,106,PROTEIN DEPOSITSPREDISPOSING FACTORS,Short BUT Ionic-binding capacity Inadequate c

7、leaning Intersubject susceptibility Heat disinfection Altered blinking Tear deficiency or altered tear composition Chronic allergies and GPC,107,PROTEIN DEPOSITSTREATMENT,Weekly protein removal recommended Replace lenses with excessive deposition,108,APPEARANCE OF LIPID DEPOSIT,Minute droplets loose

8、ly bound to the lens surface making it hydrophobic Best observed between blinks Varies with individual patients Appears as a thick, oily coating,109,ORIGIN OF LIPID DEPOSIT,Lipids are mainly from the Meibomian glands ( lipids reduce tear film evaporation),110,LIPID DEPOSITPREDISPOSING FACTORS,Tear f

9、ilm qualiy Slow blink patterns Poor lens care compliance (particularly surfactants) Careless use of inappropriate cosmetics/lotions,111,LIPID DEPOSIT,Problematic when: A thick, greasy coating decreases tears ability to spread over lens surface,112,JERRY BUMPSAPPEARANCE,Appear as a clump of raised tr

10、anslucent mulberry-like deposits Typically form in inferior, exposed portion of lens,113,JERRY BUMPSFORMATION,Non-wetting area, interacting with tear constituents Tear lipids, proteins and occasionally calcium salts are involved Gradually builds into multi-layer deposit,114,JERRY BUMPSPREDISPOSING F

11、ACTORS,Quality of tear film Poor blinking Lens surface contamination HWC LWC Aphakia cleaning,115,JERRY BUMPS,Problematic when: Large and numerous Located within pupil zone Vision and comfort affected,116,INORGANIC DEPOSITSAPPEARANCE,White crystalline specks Can be small or large Rough surface Penet

12、rate lens surface if severe,117,INORGANIC DEPOSITSPROBLEM,If heavily deposited: Damages lens surface Decreases comfort Decreases vision (if central) Removal leaves pits in lens surface,118,FUNGAL GROWTHAPPEARANCE,Filamentary growth on and into lens Usually white, brown or black,119,FUNGAL FORMATION,

13、Spores on lens surface from eye or environment Proliferates to large visible growth Penetrates lens matrix Contact lens good medium for fungal growth,120,PREDISPOSING FACTORS,Improper lens care, longed storage in unpreserved saline without disinfection Susceptible patient, poor hygiene,121,FU

14、NGUSPROBLEMS,Fungal infection can damage the cornea Vision may be affected if growth is large and in pupil area,122,FUNGUSMANAGMENT,Cannot be removed Lens must be replaced,123,FUNGAL GROWTHPREVENT FUTURE EPISODES,Disinfect after every use Educate and motivate patients on proper hygiene, care and maintenance of lens and lens care,124,LENS DISCOLOURATION,Natural lens ageing process Surface contamination Mercurial deposits,125,LENS DISCOLOURATION,Colour