Final Flashcards
(197 cards)
1
Q
Top 3 considerations with SCL
A
wet ability, mechanical, o2 perm
2
Q
Polymer in CL
A
Bind H20 or oxygen permeability.
3
Q
How to make CL
A
Hema background, polymerize, add water.
4
Q
Ways to make SCL
A
Lathe cutting, spin casting, cast molding.
5
Q
SCL Advantages
A
comfort, large size, easy to fit, decreased flare/glare, decreased spectacle blur, eye color change.
6
Q
SCL Disadvantages
A
cost, doesn’t mask astigmatism, VA, Optics, more risks, hard to verify, increased risk, life expectancy.
7
Q
When to prescribe SCL
A
spherical, low astigmatism, sports, part time, good tear film, previous GP failure, extreme refractive errors, anisometropia.
8
Q
CI with SCL
A
compromised eye: surgery, oc dz, systemic dz, poor hygiene, atopic disease, vascularization. High astigmatism or irregular.
9
Q
Extended wear
A
6 days
10
Q
DW
A
Only during the day
11
Q
FW
A
Flexible wear. Sometimes DW and sometimes EW
12
Q
Low CL H20
A
20-40
13
Q
Medium CL H20
A
41-60
14
Q
High CL H20
A
Greater than 60
15
Q
How is water content determined
A
by weight
16
Q
High water content dehydrates ______
A
More quickly.
17
Q
Low water content
A
Has more structural integrity. Stiffer.
18
Q
High water content lens ____ quicker and _____ sooner
A
dehydrates; equilibrates.
19
Q
Hydrophilic monomers
A
HEMA, GMA, VA, MA
20
Q
Non-ionic hydrophilic
A
HEMA, GMA, VA. Interaction without a formal charge
21
Q
Ionic hydrophilic
A
MA. Needs a formal charge.
22
Q
Hydrophobic monomers
A
Mechanical strength. Silicone.
23
Q
Cross Linking agents
A
mechanical strength and thermal stability.
24
Q
Silicone Hydrogel
A
Good oxygen permeability, also referred to as SCL, similar diameters.
25
DK for overnight wear
Needs to be 125 to sonly 4% occurs. 4% is swelling that occurs in closed eye.
26
What are the only lenses that meet the ability for NW
Silicone hydrogel
27
How to optimize oxygen transmission
Silicone, H20, decreased thickness.
28
DK vs H20
Increasing DK results in decreased H20. DK does not like water.
29
Biofinity
An outlier. Somehow has high water and high DK.
30
Silicone hydrogel
High DK and low H20
31
Conventional hydrogel
Low DK and high H20
32
Limbal hypermia and lenses
Less hyperemia with silicone hydrogel.
33
SCL Optics
Tear lens does not go under the tear. Don't need to take it into account. Refractive index changes with hydration and temperature.
34
Aspheric CL
Controls spherical aberrations. Get power at center but may change as leaves center. Doesn't compensate though. All peripheral rays center in the same place.
35
Spherical CL
Power is constant. Central and peripheral rays are not focused at a single point.
36
FDA Ionic division
Ionic if >0.2% ionic material
37
FDA water content division
Low >50. High
38
FDA Group 1
Low water and non-ionic
39
FDA Group 2
High water content and non ionic
40
FDA group 3
Low water content ionic
41
FDA group 4
High water content and ionic.
42
Time for a group 5
Silicone hydrogels are unique and some think they should have their own group
43
Unique silicone hydrogel
Low protein deposits, high lipid deposits, surface wet ability varies, unique solution interactions.
44
Silicone hydrogel protein deposits
Low. Less uptake than hydrogel. Concentration near the surface. More denatured. Presents as GPC.
45
Silicone hydrogel lipid deposits
more attraction. Sometimes require surfactants.
46
Modulus
High=stiffer and longer wear time. Pro: easier handling and removal. Con: comfort and moves on eye
47
Modulus of silicone hydrogels
LOW
48
Who determines replacement schedule?
ODs
49
Does replacement schedule =wear time
NO
50
Disposable
Remove and discard. Right after taken from eye throw away.
51
Quarterly replacement
Speciality CL
52
Typical SCL parameter
13.8-14 mm. 38-60%. .06-.2 mm. Sphere +6-12. Cylinder: 0 to -2.25
53
SCL fitting
Measure patients HVID and pick one 2 mm larger. Obtain central Ks. Select a BC. Evaluate
54
Time for equilibrations
5-10 minutes
55
Ideal SCL fit
1 mm from limbus, .25-.5mm with blink, .5-1.25mm with blink on up gaze.
56
Push up test
Push up and then see force required and how long to decenter.
57
Normal BC Radius
The normal BC will fit many different corneas.
58
Flat CL
May be uncomfortable due to excessive movement. May have fluting.
59
Which lens move the most
very flexible lenses as they confirm to the eye.
60
How to fix a CL that is too flat
Steepen the base curve or increase the overall lens diameter.
61
Steeping the BC ____ the fit
tightens.
62
Steep Soft lens fit.
Will not move with blink, may be initially comfortable but become tired later. Difficult to dislodge.
63
How to fix a steep CL
Decrease lens diameter, decrease BC.
64
Labeled vs. actually BC
Different brands will label different. A 8.4 BC is flatter than an 8.7 cooper vision.
65
Lid with SCL
can decenter lens. Often overlooked
66
Tear exchange with RGP
20% per blink
67
Tear exchange with SCL
1% per blink
68
Importance of tear exchange
oxygen, nutrients, debris, eliminate waste
69
IF patient tearing with lens suspect
FB beneath lens, lens inside out, solution sensitivity, Lens damage.
70
Thin lens and water evaporation
A thin lens will take water from TF.
71
Corneal radius and sagital height
greater radius=deeper.
72
Corneal diameter and sagital height
Greater diameter=greater sagittal height.
73
A steep cornea often goes with what?
A small cornea
74
Effective K
Used to assist in the selection of BC radius. Incorporated central corneal radius and corneal diameter.
75
How to calculate effective K
For every .2 mm mean K smaller than 11.8 mm subtract 1 D. For every .2 mm mean K greater than 11.8 add 1 D.
76
Selecting a SCL
Find Mean K. Calculate Effective K. Take diameter of eye. Add from the BC chart.
77
When was the first hydrogel lens approved?
1971
78
Next way to disinfect lenses?
Use heat disinfectant but since with non sterile saline. Also tired salt tablets and distilled water.
79
When was the first chemical disinfectant for SCL invented
1977.
80
Solution sensitivity
Thimerosal and/or chlorhexidine
81
Heat disinfectants
Very effective. However can denature tear secretion on the lens and affect the lens. Could do a 90s microwave.
82
Modern SCL
Affective against many organisms. Compatible with ocular tissue, lens polymers. Continue to work under many condition. Less than 1 hour for disinfection. Easy to use and cheap.
83
MPS
Cleans, rinses, disinfects.
84
Modes of Cl disinfection
1. Rub, rinse, soak 2. Rinse soak 3. immersion only
85
Recalled lens care products
Gave fungal keratitis and acanthamoeba.
86
What makes up the TF
mucous, aqueous, inorganic, organics, proteins, lipid lay.
87
What is SCL drops out due to
51% discomfort (41% dryness) 13% vision problems (reading 6%, General vision 7%)
88
Silicone Hydrogel and TF
High oxygen transmission, dehydrate slower then HEMA, SH have less protein and more lipid. May have reduced wet ability due to silicone.
89
POLYQUAD/ALDOX
Less corneal staining
90
Best cleaning for silicone hydrogel
Hydrogen peroxide
91
Disinfection times with hydrogen peroxide
Platinum disc (longer) vs. catalase.
92
Clear Care cleaning
3% peroxide for 10 minutes. Platinum disc neutralization replace the disc every 90 cycles or 3 months. Cleaning from short 5 s rinse.
93
what cleaning regime had the greatest dryness.
Clear care.
94
When are blink rates decreased
When doing cognitive tasks.
95
What cleaning system had a higher blink rate
clear care. The more frequent blink rate=dryness.
96
Oxysept peroxide system
3% peroxide for 20 min catalase enzyme neutralization in 2 hours. For all Heme and SH lenses. no preservative. Use a catalase tablet.
97
Saffron one step
FDA approved. Only one step.
98
Purilens System
UV Generating lamp, subsonic agent, preservative free saline. Use 265 nm.
99
Private label SCL care products
Older generation FDA approved MPS lens care products.
100
Enzymatic cleaners
Use to get rid of protein. ultrazyme with H202 and enzyme with h202.
101
Rinsing salines
Rinses and hydrates. Does NOT disinfect.
102
Antimicrobial lens case
Forms an electrochemical coil or battery formed with saline. Release antimicrobial silver ions.
103
how often to replace lens case
Every 3 months.
104
How much do CL wearers make up of a practice
49%
105
Cl drop out and growth
New=29%. Drop out=16%
106
Meibomian Gland Dysfunction
Obstruction causes keratinization of office, increased meibum viscosity, long term atrophy. Gland structures change with age.
107
Meiobomian gland dysfunction and CL
High MG atrophy in CL wearers. Correlates with duration of lens wear. Upper lid affected more. No difference with lens material.
108
MG Early stage
No symptoms
109
MG moderate stage
minimal to moderate discomfort, vascularization of lid margin, plugging, meibum is thicker
110
MG severe
Ocular discomfort, irregular and vascularized lid margin, meibum in thick.
111
Tx for MG
warm compress, hygiene, AT/ointment qPM, Omega3, fish oil, flax seed oil, doxycycline, azithrocycline, lipiflow. (more studies to prove Cl causes)
112
Lid wiper epitheliopathy
Proposes that inadequate lubrication creates friction and inflammation of the upper lid. Upper and lower. Stain with NaFL and Rose Bengal. Occurs 5-6 hours after Cl wear.
113
conditions associated with lid wiper epitheliopathy
Associated with dry eye disease. Exposure keratopathy, decreased mucin production, incomplete blinking, dry eye.
114
Tx for lid wiper epitheliopathy
AT
115
Dry eye disease stats and types
40% Of US has dry eye. Can be evaporative (lipid) or aqueous (aqueous)
116
CL and TF
CL splits the CL into two different section. Pre lens and pre cornea. Pre lens TF evaporates quicker.
117
Dry eye disease TX
CL change, Warm compress, punctual plugs, AT, steroids, cyclosporine, Doxycycline, Omega 3 fish oil.
118
Mucin balls
Small particles of lipid, protein, and mucin. Tear film collapses and lid interacts with epithelium and rolls these. Will be indention in cornea following lens removal. Cause no discomfort, VA decrease, or health concerns.
119
CL and mucin balls
70% have mucin balls with silicone hydrogels. Not related to age, gender, run. Higher with steep cornea, EW, and no use of rewetting drops.
120
Limbal epithelial hypertrophy
No symptoms. Seen in some long term wear HEMA wearers. Possible precursor to corneal neovascularization.
121
How to view gimbal epithelial hypertrophy
NaFL (Cannot be viewed with white light only)
122
TX for LEH
It will resolve after stop wearing CL for 3-5 days. Decrease wear time. Suspect a steep fitting lens.
123
CL papillary conjunctivitis Signs and symptoms
See blepharitis and papillae. Same as GPC. Mucus discharge in the nasal cornea of eye when wakening, itching with lens removal, decrease wear time.
124
Stage 1 CLPC
Preclinical. Tarsal conj. is normally with only a slight velvet appearance. Some mucus discharge in the AM and itching upon lens removal
125
Stage 2 CLPC
Early clinical. Increase in size and elevation of papillae. Mild itching while wearing lens. Increased lens awareness and decrease WT.
126
Stage 3 CLPC
Moderate. Increase in papillae. Increased itching and discharge. Great decrease in wear time.
127
Stage 4 CLPC
Papillae often 1 mm or larger. Severely coated lenses and decentered. Severe itching. Almost total lens intolerance.
128
What causes GPC
Antigen on CL so body starts immune response. Can get from prosthetic eye as well.
129
CLPC Tx
Rule out mechanical GPC. Manage Cl deposits. Change to preservative free. AT. Mast cell stabilizer, topical steroids, consider GPs. Surface coat SiHy with plasma coating to make more hydrophilic.
130
Surfactants
Improve cleaning
131
Preservatives
increase disinfection efficacy
132
Viscosity
Buffer the ocular tissue from preservative disinfectants.
133
Hydra-PEG
Allows more water to bind CL. Some CL already have this.
134
what causes Contact lens acute red eye
Appears as a response to endotoxins from gram neg bacteria on cl.
135
CLARE signs/symptoms
Modesto to severe bulbar hyperemia that is circumferential or sectoral. Peripheral to mid peripheral diffuse or focal infiltrations. None to mild VA reduction. Uncommon to be bilateral, A/C run, epithelial involvement.
136
CLARE Tx
D/C cl wear, lubricants and cycloplege. Steroids with severe symptoms or infiltration. Recurrence possible.
137
Superior Limbus keratoconjuctivitis
Strong association with lens care products that have thimerosal preservative (not used today).
138
SLK signs/symptoms
Increased lens awareness, burning, itching, light sensitivity, vision loss (when there is extensive pants), injection in superior bulbar conj, infiltrates, panes, cornea and conj staining, haze (v shapes towards pupil), sub-epithelial opacities, superior gimbal edema, hypertrophy, staining, and injection. Pseudo-Dendrites.
139
If you see a contact lens red eye and it is symmetrical is is CLARE or SLK?
SLK! Bilateral with symmetry but variable onset.
140
TX for SLK
discontinue SCL. Stop thimerosal exposure. New Cl (GP has no additional benefits). Scraping affected epithelium.
141
Prognosis for SLK
3 weeks-9 months. Papillary changes take longer.
142
Theodores SLK
SLK without CL wear. Over 40, F, linked to thyroid disease.
143
Superior Epithelial Arcuate Lesion Symptoms
Pt. relatively asymptomatic with maybe a slight FB sensation. usually found during routine Cl exam.
144
SEAL Signs/Symptoms
Linear breaks seen in the superior cornea of SCL wearers. In most cases eroded down to BM. Usually unilateral. Lesion .5 mm wide and 2-5 mm in length. Little or no injection of the superior bulbar conj.
145
What causes SEAL
Stiff, thick lens and high levels of dehydration
146
SEAL treatment
D/CL Cl wear. Lubricants. Topical AB? long term change base curve. Change OAD. Change material.
147
Inferior arcuate corneal staining
Coarse punctate epithelial disruption in the inferior cornea. Seen in patient with clean, well fitted wet lenses in DW or EW. May occur during lens removal. Does not depend on water content, lens thickness.
148
Solution comfort
In longer term more comfort with hydrogen peroxide
149
Dryness of MPS vs. hydrogen peroxide
Less dryness with hydrogen peroxide
150
Fusarium infection
From Renu brand.
151
Complete moisture plus infection
Acanthomoeba. infections.
152
Rub vs. no rub
Rub is much better on cleaning lens.
153
Opta-Free perservative
Aldox/polyquad
154
Preservative associated transient hyperfluorescence
Staining is though to be binding of the Nail to preservatives on eat epithelium. Preservatives have different peaks of incidence of binding. Polyquad/aldox-30 minutes. PhMB-2 hours
155
PATH Presentation
Noted after lens application. Diffuse corneal staining. Epithelium unaffected. Generally bilateral. Asymptomatic. Non-pathological. Resolution in 6-8 hours post lens removal.
156
Micro cysts
Vision is asymptomatic but comfort is symptomatic. As you decrease wear time and DK you get more cysts.
157
Micro cysts description
Small translucent or grey irregular shaped or ovoid inter epithelial cysts. Form near the BM and move toward anterior surface. Do not stain until they break through the surface. Reversed illumination tells you it is a micro cyst. Response to high levels of hypoxia.
158
Micro cyst time course
Onset is slow usually after 2 months of lens wear. Number increase and decreases in cycles. Takes 3 months to clear.
159
Micro cyst tx
decrease wear time. Change to higher Dk/T
160
What things can be seen with reversed illumination
micro cyst and mucin balls. Micro cysts don't stain with NaFL though. Mucin much bigger too. Mucin superior too.
161
Limbal hyperemia
Increased in blood flow at the gimbal arcades resulting in dilation and distention of gimbal blood vessels. Can have dilation of blood vessels and some lipid leakage.
162
Hypoxia theory for corneal vascularization
Tissue hypoxia resulting in an increased production of lactic acid which may result in venous draining. Chronic edema results in stroll softening or loss of physical barrier to vessel penetration. Hypoxia alone cannot do this
163
Vasostimulation theory for corneal vascularization
Contact lens induced epithelial trauma results in a release of enzymes. Inflammatory cells migrate to this sit and release vasostimulating agents
164
What is minimum DK for patient sleeping in lenses
125.
165
What must you do with neovascularization
Document it. Location, depth, degree of penetration, severity
166
Corneal vascularization tx
Discontinue lens wear, treat underlying pathology, minimize physiological insult.
167
Other signs of hypoxia
Vertical striae, folds in descents.
168
Epithelial vacuoles
10% nonsense wearer. Unknown etiology. Spherical fluid or gas filled vacuoles in the periphery. Generally asymptomatic and good prognosis as big turn over
169
Epithelial bullae
Low prevalence in CL wearers. Indicates chronic epithelial edema. When it breaks through the surface the patient comes in with pain.
170
Keratitis
Involves multiple layer of the cornea
171
What is an infiltrate
A focus accumulation of cells or tissue in the anterior storm. PMN leukocytes. Can be sterile or infectious
172
When will you see infiltrate with CL
with almost any chronic irritation to the cornea
173
Infiltrative Keratitis signs/ symptoms
Inflammatory reaction of cornea. Mild to moderate irritation. Redness. Occasional discharge. Can be bilateral. Va may or may not be infected. No A/C or lid edema.
174
Infiltrative keratitis causes
FB entrapment, mechanical trauma, bacterial toxins, MPS reaction.
175
Risk forzctors for infiltrative ceratisis
CL wear
176
Infiltrative keratitis Tx
D/C Cl wear temporarily. Steroids if moderate symptoms or VA decrease. Ocular lubricants. Rarely scars. Recurrence possible.
177
Contant lens peripheral ulcer signs/symptoms
Peripheral location, Modert to severe discomfort, FB sensation, slight irritation, slight redness, tearing, infiltrate, no lid edema, unilateral, no a/c reaction.
178
CLPU cause
inflammatory reaction to G+ exotoxins. Toxins release by S. Aureus on lens surface.
179
Tx for CLPU
Anti-infective agent, cycloplegia, steroids after re-eptithelium, monitor
180
Prognosis with CLPU
will always have bull's eye scaring
181
What is Microbial keratisis
Focal defect or excavation of the sub-epethial surface. Produced by sloughing of necrotic inflammatory tissue. Not the same as a corneal ulcer.
182
What causes microbial keratitis
Bacteria, protozoan, fungal, viral. Must have an acute inflammatory infiltrate of the epithelium and stroma in the presence of infectious microorganism.
183
Symptoms with microbial keratisi
can be severe to mild. May have pain, photophobia, tearing, blepharospasm, red eye, floaters, AM lid crusting, purulent discharge.
184
Signs with microbial keratitis
Central or paracentral. Large, irregular focal. Satellite lesions. Anterior stromal to full thickness. Corneal edema. Full thickness epithelial loss. Anterior chamber reaction. Lid edema. Severe bulbar and gimbal redness. Unilateral. Hypopyon.
185
MK and CL
More likely to get more severe if you sleep in them
186
CL with least chance of MK
GP
187
Peak in age of infiltration in cl
15-25 years
188
Contact lens risk survery
15-25 year olds more likely to nap in lens, sleep in lenses, expose to water.
189
Greatest risk for CL
Napping and showering in cl
190
Water exposure with CL
Some rinse CL in water. M>F. We fear acanthamoaeba.
191
Bacterial keratitis caues
Pseudomonas. Intact epithelium (corynebacterium diphtheria, listeria, haemophilus)
192
Protozoa keratitis
Appear dendritic or patchy stromal infiltrate. Symptoms dispropriate to signs. Risk factors with CL wear.
193
Fungal Keratisis
Large white infiltrate with fluffy or branching margins. Significant edema. High risk of loss of BCVA. NO STEROIDS!
194
Viral keratitis
Simplex: Terminal end bulbs. Zoster: no terminal end bulbs on psudodendrites.
195
Principals risk factor for MK
Overnight wear.
196
Endothelial Bedewing
Endothelial deposits of unknown etiology in patient who are CL intolerant. Fine white precipitates or pigment dusting of cells. Idiopathic. 20% occur in noncl wearers
197
Endothelial blebs
Black, no reflecting ares. Occurs in 100% CL wearers. Rapid onset of 10 minutes after application and resolution 2 minutes post removal. Adaption of the endothelium.
