5 - CL history and exam procedures

What is an empirical fit?

ordering the patient's lens based on measurements alone

What is the advantage of an empirical fit?

good vision with first lens

What is the disadvantage of an empirical fit?

more lens orders

What is a diagnostic fit?

trying on trial lenses to determine best fit then ordering in appropriate power

What is the advantage of a diagnostic fit?

may save visits

What is the disadvantage of a diagnostic fit?

more chair time at initial visit

What is the inventory fitting method?

lens inventory at practice is dispensed at fitting

What is the advantage to the inventory fitting method?

new lens and replacement lenses can be obtained immediately

What is the disadvantage to the inventory fitting method?

1. requires large expensive investment and commitment to fitting RGPs regularly

2. no disadvantage for soft lenses except it takes up a lot of space

What are the wear schedules of RGPs?

1. Daily Wear (DW)

2. Extended Wear (EW)

3. Continuous Wear (CW)

What is daily wear (DW)?

worn when awake only → NO overnight wear

What is Extended Wear (EW)?

CL worn up to 6+ consecutive days and nights before overnight removal

What is Continuous Wear (CW)?

CL worn up to 20+ consecutive days and nights before overnight removal

what are the disposal schedules for soft CL?

1. reusable/planned replacement

2. daily disposable

what is reusable/planned replacement disposable schedule?

contact lenses worn for multiple days, with a cleaning regiment

ex: two week, monthly, quarterly, annually

what is a daily disposable schedule?

contact lenses are worn for only one day and discarded

What were the first few materials use for GP lenses?

1. glass

2. PMMA

What is the oxygen transmission of PMMA?

zero

what is keratometry?

measure of central corneal curvature using corneal topography

What is HVID?

horizontal visible iris diameter measured with a PD ruler or topography

What is the average corneal power?

43.5 ± 1.7D

what is the mean corneal astigmatism?

0.9 ± 1.1D

What is the average HVID?

11.5mm → range 10 to 13.5 mm

What are the some questions to ask during case history for cls patients?

1. what lens(es) worn? how many years?

2. wear schedule?

3. which solution?

4. how often do you sleep in your contact lenses?

5. ask about hand washing

6. tell me what you do with the case after you put your lenses in?

What is an over-refraction?

same as general refraction but while wearing a CL

what is spherical over-refraction?

performed when you do not intend to prescribe cylinder

what is sphero-cylindrical over-refraction?

performed to see if correcting astigmatism improves VAs and/or when prescribing a toric lens

what can you use to do an over-refraction?

1. loose lenses (flippers)

2. phoropter

what do you add the over-refraction to?

add the OR to the CL power

need to vertex if +/->4.00 D

is vertex required for the CL on the eye?

NO vertex is required for the CL → already on the eye

When do you need to vertex the over-refraction?

if >±4.00

What are the steps of a dispensing CL visit?

1. check habitual VA

2. inquire about Hx change

3. instill proparacaine for rigid lenses

4. insert lenses and allow to settle (10-15 mins)

5. assess VA

6. check fit

7. over-refraction

8. dispense if acuity + fit are acceptable with minimal OR → otherwise re-fit

how long does a soft CL dispense visit usually take?

20 minutes or less