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Contact Lenses 3 > unit 2 cont.. (quiz 3) > Flashcards

unit 2 cont.. (quiz 3) Flashcards

(63 cards)

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1
Q

what is lens surface crazing

A

-surface cracks in the GP
-appear as multple cracks or a mesh-like lattice

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2
Q

symptoms of lens surface crazing

A

poor or fluctuating vision

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3
Q

causes of lens surface crazing

A

-matierial related problems
–weakness in the structure of the lens material or surface stress induced lens manufacture
-patient use of alcohol based cleaners

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4
Q

treatment for lens surface crazing

A

-it is not possible to remove the surface cracks
-GP lenses must be replaced

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5
Q

dimple veiling

A

-trapped air bubbles underneath the GP lens -> causes pits to form in the cornea
-Not true staining
-DO NOT move with the tear film when blinking
-appear as bright green dots
-once CL is moved it goes away

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6
Q

symptoms of dimple veiling

A

sometimes reduced vision
-reduces the corneas optics

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7
Q

causes of dimple veiling

A

steep fitting GP CL

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8
Q

treatment for dimple veiling

A

flatten the lens
-flatten the BC or decrease diameter

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9
Q

why does wettability matter?

A
  • a non-wet surface allows lens depostis to attach to the lens easily
    -A non-wet surface decreases a pxs VA
    -a non-wet surface increases friction with the inner eyelid which can cause discomfort
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10
Q

how does poor surface wettability appear?

A

-appears as “beads” of liquid on the lens surface
-can also have a filmy or deposit like apperance

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11
Q

Causes of poor wettability

A

-matieral or manufacturing problem of the GP
-Lenses may have a waxy residue from the production proccess
-px related issues..
-improper cleaning
-dry eye disease
-use of lanolin-containing soap/lotion

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12
Q

treatment options for poor wettability for CL issues

A

-pre soak the lens overnight prior to dispense
-use a solvent followed by reconditioning with wetting solution
-plasma treatment to remove waxy residue
-refit to a diff lens matieral

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13
Q

treatment causes for poor wettability in respect to px cause

A

-make sure the px learns proper technique for care including rubbing lenses and using the solution properly
-avoid lanolin creams and soap prior to handling lens
-treat dry eye desease

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14
Q

5 layers of cornea

A

-epithelium
-bowmans layer
-stroma
-descemets membrane
-endothelium

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15
Q

how corneal infection develops

A
  1. corneal epithelium is damaged
  2. microbes invade cornea
  3. immune response activated
  4. cornea becomes inflamed
  5. microbes penetrate deeper and cause scaring
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16
Q

The avascular cornea

A

-the cornea is avascular (without blood vessels)
-when a px wears CLs, oxygen flow to the cornea is reduced
-can lead to cornea hypoxia (lack of oxygen to cornea)

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17
Q

corneal hypoxia

A

-primarily caused by CL wear
-causes a series of events to occur which impacts corneal health

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18
Q

how to reduce risk of corneal hypoxia

A

-using contact lens materials with high oxygen transmisibility (DK/t)
-avoid over wear of extended wear of CLs

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19
Q

corneal neovasularization

A

-happens when the cornea continues to receive limited oxygen, this can cause new blood vessels to grow from the conjunctiva into the cornea

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20
Q

symptoms of corneal neovascularization

A

-sometimes no symptoms (if mild)
-cloudy/hazy vision (if severe)
-from damage to the clear corneal tissue (loss of transparency)
-from blood veseels blocking or bending light entering the eyes

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21
Q

treatment options for neovascularization

A

-refit to a more breathable lens
-discontinue CL wear until resolved
-px education

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22
Q

Limbal vessel encroachment

A

-Precursor or ‘warning sign’ of future neovascularization
-increase in limbal vasculature and extension into the hazy zone of the limbus

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23
Q

what is corneal infiltrates

A

-inflammatory cells in the corneal tissue
-grey or white in apperance
-Indicates that white blood cells have migrated to the stroma

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24
Q

symptoms of corneal infiltrates

A

-sometimes asymptomatic
-irritated, watery eyes

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25
types of corneal infiltrates
1. Infectious -> Bacteria, viruses 2. Sterile-> means NOT infectious -CL wear is the most common cause of sterile infiltrates
26
what is a corneal ulcer
-an open sore in the outer layer of the cornea -most commonly caused by an infection -other causes .. severe dry eyes, abrasions or burns -ulcer is best visualized with fluorescein (appear green)
27
apperance of a corneal ulcer
white spot or mark on the cornea that stains with fluroscien
28
Main risk factor of corneal ulcer
CL wear is the #1 risk factor -in contact lens wearers, ulcers can cause permanent vision loss -treat quickly to avoid corneal staining -URGENT REFERRAL
29
difference between infiltrate and ulcer
-Infiltrate= white blood cells in corneal stroma, hazy/white with no fluroscein stain -ulcer= loss of stromal tissue, causing a divot, can also be hazy but ALWAYS stains with fluroscein
30
can infiltrates sometimes later turn into an ulcer?
yes, but not always
31
do infiltrates and ulcers represent a sign of another disease?
yes, they can exist as their own conditino but also represent a sign of another disease state such as -contact lens specific conditions -keratits
32
CLARE - contact lens acute red eye
-inflammation of the outer surface of the eye -only occurs in pxs wearing CLs (most common from extended wear) -inflammation results from lack of oxygen, contamination of the CL with bacteria or protein deposits NOT A TRUE CORNEAL INFECTION
33
what do you see when someone has CLARE
-corneal infiltrates -conjuctival redness
34
signs of CLARE
-360 degrees red eye, often worse near the limbus -infiltrates, often multiple -ususally unilateral -NO staining w/ fluroscein
35
symptoms of CLARE
-Typically in extended wear CL pxs who wake up with red and painful eye (after sleeping in CL) -watery -irritated
36
treatment of CLARE
-discontinue CL wear until resolved -Refer - might need medicated eye gtts like a steroid -prescribe new CLs: daily, or lenses with higher Dk/t -improve px habits
37
CLPU - contact lens peripheral ulcer
-inflammatory condition causing loss of epithelial and stromal tissue -a sterial ulcer (NOT INFECTIOUS)
38
apperance of CLPU
-infiltrate with fluroscein stain in peripheral location -small -circular -well defined
39
how to reduce bacterial sources to prevent reocurrence
-lid hygiene -increase CL replacement -chance care system/solution
40
what happens when you discontinue CL wear when you have CLPU
typically heals is 3-4 days -faint scar may persist for several months
41
what is Keratits
-inflammation of the cornea -may or may not be associated with an infection -generally affects one eye -all cases require an urgent referral to prevent permanent vision loss
42
2 types of keratits
-Non infectious keratits -infectious keratits
43
Types of noninfectious keratits
1. Toxic keratits 2. Vascularized limbal keratits -caused by an eye injury (scratch or damage to corneal surface)
44
types of infectious keratits
1. bacterial keratits 2. fungal keratitis 3. acanthamoeba keratits 4. viral keratitis
45
symptom of keratitis
- red eye -eye pain -blurry vision -watery eyes
46
Keratitis signs
-Possible infiltrate -possible ulcer
47
toxic keratitis
-direct contact of hydrogen peroxide cleaning solutions with the eye -appear as small dot-like opacities on the cornea that stain w/ fluroscein
48
treatment for toxic keratitis
-irrigate eyes -artifical tears -no CLs until resolved -px education
49
Vascularixed limbal keratitis (VLK)
-rare complication of GP lens wear -most commonly from extended wear of GP lenses which damage the limbal stem cells -chronic 3 and 9 staining can lead to the development of VLK
50
3 clinical signs associated with VLK
1. severe 3 and 9 staining 2. raised, inflamed, semi-opaque epithelial lesion 3. localized vascularization of conrea
51
symptoms of VLK
-lens awareness -localized ocular pain -red eye w/ elevated corneal mass upon self inspection in mirror
52
treatment of VLK
-ATs -evaluate lens and fit -evaluate lens diameter (consider smaller diameter to decrease mechanical irritation to limbus and cornea)
53
CL related risk factors for developing infectious keratits
-sleeping in CLs -swimming/showering in CLs -poor CL hygeine habits -improper CL solution use -not disposing of CLs as directed
54
How common is infectious keratitis
-approx 2-20 cases per 10,000 contact lens wearers each year -90% of cases were in soft CL -10% of cases were in GP
55
Bacterial keratitis
-most common form of keratitis (90% of cases) -develops rapidly (2-3 days) -In CL wearers, bacterial keratitis is most commonly caused by a bacterial called pseudomonas aeruginosa -round/oval white lesions
56
what do pseudomonas do
easily attach to the surface of CLs and survive in ocular enviroments
57
signs and symptoms of bacterial keratitis
-eye pain -blurry vision -red eye -mucopurulent discharge -eyelid swelling -hazy cornea (infiltrate) -hypopyon -anteriror chamber reaction
58
treatment of bacterial keratitis
-emergency referral -antibiotic eye drops (depending on severity. may use gtts as frequently as every 30mins) -possibly oral antibiotics -no CL wear until resolved -can use eye gtts to control pain (cycloplegic)
59
viral keratitis
-history of cold sores -dendritic ulcer (branching epithelial defect)
60
fungal keratitis
-trauma, vegetative/outdoor -infiltrate with feathery edges -grey-white lesion
61
protozoal keratitis AKA acanthamoeba
-contact lenses (poor hygeine) -ring shaped infiltrate
62
how thick is the cornea?
540um
63
corneal anatomy
-no blood vessels to supply nutrients or protect against infection -Nutrients via diffusion ~tear film/air ~aqueous humor ~closed eyelids -robust limbal blood supply -transparent ~nonvascular ~dehydrated

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