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YEAR 3 > CONTACT LENSES > Flashcards

CONTACT LENSES Flashcards

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1
Q

A patient wears a 9.50mm diameter lens, what type of lens is this likely to be?

A

RGP corneal lens.
Typically smaller in total diameter designed to fit within the limbus.
8.5mm to 10.5mm

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2
Q

Four advantages of RPG lenses

A

1.Oxygen permeability;
Allows more oxygen to reach the cornea directly
2.Visual acuity;
Superior VA’s due to masking of corneal irregularities
3.Deposit resistance;
Attracts fewer protein and lipid deposits making them more hygienic
4.Durability and cost efficiency;
Long lasting and more economical

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3
Q

Keratometry reading of 7.90mm. What is the likely BOZR?

A

Approximately 8.00mm

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4
Q

Advantages of single vision CL’s with reading correction

A

-Clear DV
-Useful for people who don’t want to wear glasses all day

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5
Q

Disadvantages of single vision CL’s with reading correction

A

-Reading glasses still need to be worn for near tasks
-Inconvenience for activities that require frequent focus changes

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6
Q

Advantages of Mono correction

A

-No need for additional specs
-Often more affordable than multifocal lenses

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7
Q

Disadvantages of mono correction

A

-May reduce binocular vision quality
-Reduced depth perception

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8
Q

Advantages of multifocal correction

A

-Provide simultaneous correction for both distance and near
-Offer freedom from spectacles

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9
Q

Disadvantages of multifocal correction

A

-Visual quality may be reduced
-More complex fitting
-Expensive

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10
Q

Buffering agent currently found in soft contact lens solution

A

Borac acid

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11
Q

Steps to remove RGPs

A
  1. Wash hands
  2. Stand over clean surface
  3. Keep both eyes open
  4. Pull outer canthus with index finger
  5. Position other hand palm-up under the eye
  6. Blink firmly
  7. Lens will pop out due to pressure and land in palm
  8. Alternatively use a suction remover
  9. Clean lens if reusable and store
  10. Never pinch lens directly off the eye
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12
Q

Px put RGP’s in straight from solution, describe course of action

A
  1. Reassure patient
  2. Immediately remove lens
  3. Advice px to irrigate eye
  4. Check for symptoms
  5. Observe signs without slit lamp
  6. Explain solutions not designed for direct ocular contact
  7. Do not attempt to treat
  8. Advise seek urgent medical attention
  9. Record all observations/ actions taken
  10. Ensure follow up is arranged
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13
Q

Likely behaviour/ fitting appearance of soft CL on the eye

A

-Reduced centration
-Edge lift may be visible
-Discomfort or awareness
-Reduced stability
-Dislodged more easily
-2mm larger than HVID

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14
Q

Methods to ensure CL is right way around

A
  1. Taco test; place lens of fingertips and gently squeeze lens edges together if Inside out; edges flare out or stay flat. If correct; edges roll inwards
  2. Profile test; place lens on fingertip with bowl facing up. If inside out; edges appear flared. If correct; smooth curve
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15
Q

Bullous Keratopathy and CL benefit

A

-Painful ocular condition caused by corneal endothelia decomposition
-Therapeutic bandage
-Relieves pain
-Promotes healing
-Improves visual comfort

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16
Q

Aniridia and CL benefits

A

-Part or all of the iris is missing, causing glare and reduces VAs
-Tinted or painted CLs to control light sensitivity
-Contrast sensitivity
-Visual comfort
-Cosmetic improvement

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17
Q

Trichiasis and CLs benefits

A

-Misdirection of eyelashes towards the cornea
-Bandage
-Protective layer
-Minimises friction
-Short term solution

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18
Q

Reasons for decline of PMMA as a contact lens solution

A

Zero oxygen permeability which led to;
-corneal hypoxia and discomfort
-corneal oedema
-Neovascularisation
-poor extended wear
-lower comfort

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19
Q

Contact lenses over glasses for sport;

A
  1. Improved safety; specs may break
  2. Wider field of view; move with the eyes
  3. Better visual stability; no slipping or fogging
  4. Improved self confidence; less self conscious
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20
Q

Edge lift

A

Definition; clearance between peripheral edge and corneal surface
Purpose; facilitates tear exchange

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21
Q

Multi curve

A

Definition; lens design incorporating multiple back surface curves
Purpose; improves alignment with corneal contour

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22
Q

Examples of daily disposable single vision toric lenses

A

-Acuvue Oasys 1-day for astigmatism
-AquaComfort plus toric
-MyDay toric

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23
Q

2 measures of VA which constitute the minimum eyesight standards for UK drivers

A
  1. Reading number plates at 20 meters;
    -All group 1 drivers must be able to read this
    -Tested outdoors using a physical plate
    -Legal requirement
  2. Snellen visual acuity standard;
    -DVLA requires minimum of 6/12 binocularly
    -Tested using Snellen chart
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24
Q

8 elements of a routine CL aftercare appointment

A
  1. History and symptoms
  2. Visual acuity
  3. Over-refraction (if indicated)
  4. Lens fit assessment
  5. Lens surface condition
  6. Ocular health assessment (slit lamp)
  7. Tear film assessment
  8. Education and compliance review
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25
Example of minor use which may be identified during an aftercare
-Issue; Contact lens induced conjunctival hyperaemia -Signs; redness, mild injection around limbal area -Symptoms; mild discomfort, dryness, awareness of lens -Cause; reduced oxygen transmission, poor or overwear -Outcome; lens material review, lens fit adjustment, ocular lubricant, compliance reinforcement, monitor, referral
26
27
Risks of swimming in CLs
-Microbial contamination -Lens loss or displacement -Deposits or discomfort
28
Advice with regards to swimming in CLs
1. Avoid altogether 2. If insists, wear disposables 3. Never wear underwater without goggles 4. Reinforce hygiene 5. Consider prescription goggles
29
Name a potential serious complication of swimming in CLs
Acanthamoeba keratitis; -rare but severe -result in intense pain, redness, photophobia, vision loss -often linked to water exposure in CLs
30
Acanthomoeba keratitis
Signs and symptoms; -severe ocular pain -photophobia -blurred vision -ring infiltrate -history of swimming/showering in lenses
31
Actions taken if see signs of acanthomoeba keratitis
1. Remove contact lenses immediately 2. Do not attempt treatment 3. Urgently refer to HES or A+E 4. Clearly document everything 5. Reinforce importance of early intervention
32
Entropian and CLs benefits
-Malposition of eyelid margin where lid turns inwards -lashes rub against cornea -bandage soft lens -physical barrier -prevents abrasions -allows epithelial healing -may be used temporarily before surgery
33
Nystagmus and CLs benefits
-Involuntary oscillation of eyes -often leads to blurred vision -more stable image -improved VAs -cosmetic tint reduces awareness -enhance confidence
34
Persistent corneal epithelial defect
-non healing break in corneal epithelium lasting 10-14 days -therapeutic lenses -moist healing environment -reduce mechanical trauma -promotes epithelial migration -may be combined with topical medications
35
Steps to reposition RGP CLs
1. Wash and dry hands 2. Stand in front of mirror 3. Locate dislodged CL 4. Gently manipulate lens with finger 5. If unsuccessful close eye and massage lids 6. Avoid pressure 7. If too dry take out, rinse in saline and reinsert 8. Reassure patient
36
Reason for including a chelating agent in CL solution
-Included to bind metal ions -Reduces risk of deposit formation -Maintain solution stability
37
How to identify daily disposable CLs
1. Lens packaging labels 2. Visible markings 3. Lens stability features 4. Clinical observation
38
Microorganism responsible for causing a dendritic ulcer in microbial keratitis
Herpes Simplex Virus
39
3 signs without the use of slit lamp for microbial keratitis
1. Redness; particularly around cornea 2. Watery discharge; indicates secondary infection 3.. Photophobia; sensitivity to light
40
Symptoms of microbial keratitis
1. Eye pain/ foreign body sensation; sudden onset 2. Blurred vision; due to corneal ulcer 3. Tearing
41
Course of action if suspected microbial keratitis
1. Do not attempt to treat 2. Remove contact lenses immediately 3. Advise px to seek urgent medical attention 4. Provide written documentation 5. Reassure patient 6. Document all observation and actions 7. Advise against CL wear until seen by medical practitioner
42
4 potential symptoms of CL related complications
1. Redness 2. Pain or discomfort 3. Blurred or reduced vision 4. Photophobia
43
Advantages of silicone hydrogel CLs
1. Higher oxygen permeability; greater oxygen transmission 2. Lower water dependence; don’t rely on water content to transmit oxygen
44
4 signs of poor fitting CLs without slit lamp
1. Lens decentration 2. Excessive lens movement 3. Redness 4. Excessive tearing
45
4 symptoms of poor fitting CLs without slit lamp
1. Discomfort/ foreign body sensation 2. Blurred vision 3. Dryness 4. Awareness of lens
46
2 solutions to discomfort of CLs due to poor fitting
1. Refit with flatter base curve; improve movement and reduce tightness 2. Change material or design; less stiffness reduces mechanical pressure
47
Back Optic Zone Radius (BOZR)
-Central curvature of back surface of CL that aligns with the cornea -Influences lens fit and centration
48
Total diameter (TD)
-Overall width of the CL from edge to edge -Affects stability, centration and coverage
49
Back Vertex Power (BVP)
-Effective power of the lens -Must be vertex compensated
50
Presbyopia
Age related condition characterised by progressive loss of the eyes ability to focus on near objects. Caused by reduction in lens elasticity and accommodative amplitude. Typically early to mid 40s
51
Symptoms of presbyopia
1. Difficulty reading small print 2. Needing to hold objects further away 3. Eye strain/ headaches 4. Blurry near vision
52
2 types of soft multifocal CL designs
1. Centre distance design; -distance correction in centre -progressive increase -ideal for prioritising distance -useful for active people 2. Centre near design; -near correction in centre -distance in mid periphery -prioritising near tasks -daily disposable
53
4 factors to consider when deciding on soft multifocal CLs
1. Visual needs/ lifestyle; DV, NV, IV 2. Pupil size; affects which zone receives dominant image 3. Refractive error/ ADD; different designs perform better 4. Previous CL experience; familiarity improve adaption
54
Example of multifocal CL
Dailies total1 multifocal (Alcon) Utilities centre-near aspheric design
55
KERATOCONUS
-Progressive non-inflammatory corneal ectasia where cornea becomes thinner and conical in shape. -Leads to irregular astigmatism and myopia -Typically present in adolescence -Usually bilateral
56
3 signs of keratoconus observed using slit lamp
1. Fleichers ring; iron deposits forming a brown ring 2. Corneal thinning; often inferiorly 3. Scarring especially in advanced stages
57
3 symptoms of keratoconus
1. Blurring vision; progressive overtime 2. Increased light sensitivity 3. Frequent changes in prescription; without improvement
58
CLs suitable for keratoconus
1. RGP’s; masks irregular corneal surface, custom fitted 2. Hybrid lenses; rigid centre, those who can’t tolerate RGPs 3. Scleral lenses; large diameter that vaults the cornea, comfort
59
How does fluorescein differ between rigid and soft lenses
1. Rigid; -applied whilst lens is on the eye -does not absorb into RGP -highlights tear film pattern 2. Soft lenses; -stains and discolours -lens must be removed before instillation
60
Symptoms of dry eye
1. Burning/ stinging 2. Grittiness 3. Foreign body sensation 4. Intermittent blurred vision 5. Excessive tearing 6. Redness 7. Discomfort
61
Signs of dry eye observed using slit lamp
1. Reduced tear height 2. Redness 3. Punctuate epithelia erosions on cornea 4. Rapid tear break up time 5. Music strands/ debris
62
Possible causes of dry eye
1. Aging 2. Hormonal changes 3. Systemic medications 4. Environmental factors 5. Contact lenses
63
How does dry eye effect CL wear
-reduced comfort -poor vision -insufficient tear film -lens tolerance -increased risk of complications -deposit formation -management strategies -lubricants
64
Corneal oedema
Accumulation of fluid within the corneal layers due to disruption of endothelial pump fiction. Causes loss of corneal transparency Can be temporary
65
3 possible causes of corneal oedema
1. Hypoxia 2. Surgical trauma 3. Endothelia cell dysfunction
66
3 symptoms of corneal oedema
1. Blurred/ hazy vision 2. Halos around lights 3. Eye discomfort/ mild pain
67
3 signs seen using slit lamp of corneal oedema
1. Corneal hazing 2. Epithelial micro cyst 3. Epithelial bullae
68
How might CL wear contribute to corneal oedema
-insufficient oxygen delivery due to thick material -overwear -tight lens syndrome -poor lens choice -inadequate aftercare

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