Brainscape's Knowledge GenomeTM

Browse over 1 million classes created by top students, professors, publishers, and experts.


See full index

OD3 Advanced Contact Lenses > 1. Intro to Advanced CLs > Flashcards

1. Intro to Advanced CLs Flashcards

1
Q

What are the 3 aspects that help determine whether a patient is a good candidate for CLs during history taking?

A
  1. Motivation level
  2. General or ocular health - medications (Roacutane, SSRIs, OCP), prior ocular hx (bleph, marginal keratitis…)
  3. Personal considerations - activities, occupation, working environment, visual tasks, hygiene, manual dexterity, intended wearing schedule
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
2
Q

What are the 4 common indications for CLs during ocular examination?

A
  • High refractive error
  • Anisometropia
  • Presbyopia
  • Elective paediatric
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
3
Q

What are the 5 uncommon indications for CLs during extensive ocular examination?

A
  • Corneal irregularity - PMD, KCN
  • Ocular disfigurement - aniridia, diplopia, torn iris, trauma
  • Post-keratoplasty
  • Paediatric - aphakia
  • Bandage CLs - RCE, bullous keratopathy, exposure keratitis
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
4
Q

What are the 9 indications where you should pay extra attention to with CL wear?

A
  • Cosmetically noticeable strabismus
  • Dry eye/ Tear film instability
  • Ocular allergies/ hayfever/ atopy
  • Ocular surface disease - pingueculae, ptergia
  • Eyelid disease - chalazion, anterior or posterior bleph
  • Glaucoma - topical medications
  • Hx of keratitis
  • Decreased corneal sensitivity - diabetes
  • Delayed wound healing - diabetes, immunocompromised
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
5
Q

What are the 10 general health considerations for CL wear?

A
  • Smoking
  • Poor hygiene
  • Chronic sinusitis, allergies, hayfever
  • Skin issues - acne rosacea, atopic eczema
  • Diabetes
  • Thyroid disease
  • Oral herpes simplex
  • Pregnancy/ endocrine changes
  • Systemic medications
  • Arthritis/ manual dexterity
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
6
Q

6 Baseline Examination for CL Assessment
1. Complete ...
2. ... vision
3. Refraction & VA (incl. ..., near ..., type of ...)
4. Full comprehensive examination - routine, ..., ..., slit lamp (..., NaFl, ..., tear ... & ... for presbyopes), fundus, routine ...
5. Other measurements - ..., pupil ..., ..., lid ..., ...
6. ...

A

6 Baseline Examination for CL Assessment
1. Complete Hx
2. Unaided vision
3. Refraction & VA (incl. vertex distance, near WD, type of near correction)
4. Full comprehensive examination - routine, excursion, pupils, slit lamp (lid eversion, NaFl, TBUT, tear volume & stablity for presbyopes), fundus, routine dilation
5. Other measurements - HVID, pupil diameter, palpebral aperture, lid tightness, ocular dominance
6. Corneal topography

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
7
Q

Name the 8 ISO terms for CLs parameters in order

A
  1. BOZR - Back Optic Zone Radius
  2. TD - Total Diameter
  3. BVP - Back Vertex Power
  4. Water Content
  5. Dk
  6. Material
  7. Design
  8. Thickness
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
8
Q

What does Dk stand for? What is the unit?

A

Dk is oxygen permeability, whihc is the amount of oxygen passing through a CL material over a set amount of time and pressure difference. Measured in 1 Barrer.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
9
Q

What does Dk/t stand for?

A

Dk/t is the oxygen transmissibility. It is the amount of oxygen passing through a CL of specified thickness over a set amount of time and pressure difference.

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
10
Q

What is considered average, steep and flat K readings? Which ISO term is this represented by?

A

Average: 43.0D or 7.8mm
Steep: >45.0D or <7.5mm
Flat: <41.0D or >8.2mm
Usually represented by BOZR in mm

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
11
Q

What is an ideal Total Diameter of a CL?

A

2.0mm larger than the px’s HVID

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
12
Q

What are the consequences of a large TD and small TD?

A
  • Large TD - reduced lens movement and inadequate tear exchange
  • Small TD - excessive movement, poor centration, and less comfort
How well did you know this?
1
Not at all
2
3
4
5
Perfectly
13
Q

How is spherical equivalent of a astigmatic Rx determined?

A

SE (D) = sphere + 0.5 (cylinder)

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
14
Q

When should the effectivity equation be used? State the equation.

A

For spectacle refractions ≥ ±4.00DS
F(OC) = F(S) / (1-d F(s))
d = vertex distance in m

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
15
Q

What is the preferred CL material nowadays? Why?

A

SiHy
* Less mechanical issues
* Generally thinner
* Higher Dk/t

How well did you know this?
1
Not at all
2
3
4
5
Perfectly
16
Q

What are the 5 steps of SCL fitting evaluation? What about for toric SCLs?

A

Spherical SCL: 2C MAP
Toric SCL: 2C MAP + RS
Centration
Coverage
Movement
Acuity
Push-up
Rotation
Stability

17
Q

What are the 3 important points about lens centration?

A
  • Does the centre of the lens align with the centre of the cornea?
  • Does the lens continue to align with the cornea in each position of gaze?
  • How much lens lag? (acceptable if 0.3-0.7mm)
18
Q

What should be considered when looking at lens coverage?

A

Lens should not be cover the corneal limbus to prevent compressing on limbal stem cells. Ideally ≥ 1mm coverage in all positions of gaze.

19
Q

Why is lens movement important?

A

Promotes postlens tear filim exchange and mixing.

20
Q

How is the push-up test conducted? Why is this done?

A

When px is in primary gaze, optom pushes lens superiorly by manipulating inferior eyelid margin. Well-fitting lens should be easily moved and will rapidly return to central location.
This indicates lens mobility independent of the px’s eyelid blink dynamics.

21
Q

How is good VA achieved with CL wear? (5 points)

A
  • Accurate refraction (lens effectivity)
  • Appropriate lens selection
  • Good lens centration
  • Good movement
  • Good pre-lens tear film stability
22
Q

Why should we prioritise px having the same type of CLs on both eyes e.g. both spheres instead of sphere + toric?

A

Comfort differs between toric and spherical CLs. If px’s astig is not too high or VA is acceptable with spherical equivalent, we should use same type. Px is more likely to have success using CLs.

23
Q

How is the direction of lens rotation determined?

A

Using 6 o’clock mark as reference: is the lens rotating to the right or left? How much rotation is there? (<10 degrees is acceptable).
Over-refraction can also be used.

24
Q

How is Rx compensated when there is lens rotation?

A

Using LARS: left add, right subtract
Estimate the degree and direction of rotation and calculate the new Rx should be ordered.

25
Q

How is lens stability determined?

A

Looking at whether the degree of rotation is constant between blinks.

26
Q

What should be altered when lens stability is poor?

A
  • Change stabilisation methods
  • Change BOZR (BOZR too flat)
  • Change diameter (TD too small)
27
Q

What is the preferred wearing time before a px attends their CL aftercare?

A

At least 1 hour prior to appointment

OD3 Advanced Contact Lenses (9 decks)

Brainscape helps you reach your goals faster, through stronger study habits.
© 2024 Bold Learning Solutions. Terms and Conditions