CL Reviewer Flashcards
he pioneered development of continuous wear of soft CL
John de Carte
he is considered to be father of RGP
Leonardo Seidner
he conceived the concept of throwaway lenses
Orlando Battista
first commercially available disposable lens
Danalens
he developed the first commercially available disposable lens
Michael Bay
first commercially available daily disposable CL
Johnson and Johnson
RGP stands for
Rigid Gas Permeable
PPMA stands for
Polymethyl-Methacrylate
he understood that better vision could be achieved by enlarging the retinal image
Rene Descartes
he proved that cornea played no part in the accommodative process
Thomas Young
he is considered as father of CL
Sir John Herschel
he is the first person to apply therapeutic contact device on the eye
William White Cooper
he devised the first CL for keratoconus
Eugene Kalt
limitations of keratometry
- Small area measured; periphery & apex not measured
- Assumes cornea is a spherical surface: accuracy is questionable
- Irregular topography not described specifically & sometimes undetected
the color that indicates the steepest curve in a corneal videokeratography
Red
CL design where in back surface has two curvature all throughout is
CL design wherein back surface has two curvature
gradual change in curvature from center to periphery of optic zone
Aspherical design
Lens-cornea relationship wherein the CL is more curved than the cornea
The eccentricity value of the apex of the cornea is roughly
0.50
TRUE about Reverse geometry design, EXCEPT:
a. central portion of lens is steeper than periphery
b. for post-surgical “plateu” topographies
c. for myopia reduction
A
True about back vertex power exceot
a. same w px refractive error
b. combines w LL to provide total refractive correction
c. determined by diagnostic lens
d. checked emperically using K reading
A
true about base curve of SCL except
a. aka Sagittal depth
b. tends to be much steeper than K
c. Same as RGP
d. range is 8.00 to 9.2mm
B
true about lens diameter of SCL except
a. larger than RGP
b. creates greater sag
c. increase stability & comfort
d. increase tear exchange
D
wearing sched where CL is only worn when px is awake
Daily wear
wearing sched wherein CL can be worn 7 days without removal
Extended wear
true of Conventional except
a. lens is replaced when there is need for replacement
b. typically 12 months for SCL
c. px receives one pair at a time
d. less lens care required
D
true of Frequent Replacement except
a. aka Programmed replacement
b. lens is frequent replaced
c. lens is worn in DW basis only
d. fewer complications
C
true of disposable CL except
a. one time use
b. no lens care
c. more convenience
d. less costly
D
true of Handling tints except
a. does not aid in lens handling
b. almost all tints have handling tints
c. can be seen more easily
d. not meant to change eye color
A
true of Opaque tints, except
a. change irises to diff color
b. may see some iris through clear pupil
c. mask underlying iris color
d. no blur on edge
D
true of spincasting except
a. oldest form of CL manufacturing
b. very expensive
c. discovered by Witcherle
d. reproducible
B
FDA grouping of CL with low water content & ionic
Group 3
FDA grouping with high water content and non-ionic
Group 2
FDA grouping with low water content and non-ionic
Group 1
FDA grouping with high water content and ionic
Group 2
amount of astig brought by refractive surfaces especially cornea is called
Residual
According to FDA, CL can be classified as low water content if
it contains less than 50% water
purpose of inversion markers
tells if lens is inside-out
range of water content in SCL
25 to 74%
wearing sched wherein lenses are worn 30 days straight
Continuous wear
SCL worn alternately with eyeglass prescription is called
Occasional wear
which scenario is the safest
D. A CL designed for continuous wear used in daily manner
which scenario is the least safe
C. A CL designed for daily wear used in continuous manner
true about lacrimal lens in RGP except
D. using thick lens formula in solving the power
true about low water content hydrogel except
a. poor durability handling
b. fewer deposits
c. lower Dk
d. can be made thinner
A
true about high water content except
a. higher dk
b. used more often for extended wear
c. more deposits
d. can be made thinner
D
if BC of CL is steeper than K reading in HCL, the power of lacrimal lens will be
Plus
if BC of CL is flatter than K reading in HCL, the power of lacrimal lens will be
Minus
if BC of CL is on-k in HCL, the power of lacrimal lens will be
Plano
the LL in SCL is said to always be
Plano
if cornea is astigmatic, the power of LL will be
Cylindrical
the amount of astig manifested with CL on the eyes called
Residual astig
true about water content except
a. water is bound within hydrophilic polymer matrix to provide flexibility & oxygen permeability
b. amount of water determines material characteristics
c. very important in silicone hydrogels since O2 depends on it
NO EXCEPTION
advantages of SCL over HCL except
a. better initial comfort
b. easier part time wear
c. more spectacles blur
d. more frequent replacement
C
advantages of HCL over SCL except
a. sharper VA
b. better deposit resistance
c. greater durability
d. cost is higher
D
acceptable blink movement in primary gaze
0.5 to 2mm
for conventional hydrogel CL the grouping which would be best will be
Group 2
CL modality schedules by optometrist not manufacturer
CL modality most convenient
Daily disposable
CL modality that a pair can be used for 12 months
Conventional
CL modality where a CL can be worn for a month
Monthly disposable
CL modality that needs the most contact solution would be
Conventional
Cl modality where confusion will arise in usage of lens
Frequent replacement
the cheapest CL modality
Conventional
type of lens where oxygen transmissibility is so high it can be worn for 30 days straight without removal
Continuous wear
type of lens where lens may be used only when px is awake
Daily wear
type of sched where px alternates usage of CL & spectacle lens
Occasional wear
wearing sched suggests lens can be worn 7 days straight
Extended wear
wearing sched that we encourage to our px no matter what oxygen transmissibility of lens is
Daily lens (chatgpt)
lens with Dk/t of 23 will be good for
Daily wear
lens with Dk/t of 50 will be good for
Daily wear (chatgpt)
lens with Dk/t of 87 will be good for
Continuous wear
silicone hydrogel lens is the only one allowed for this modality
Continuous wear
the LL produced when BC radius of Cl is flatter than curvature of cornea
Minus
primary advantage of SCL over HCL
- clarity of vision
- comfort
- ease of wearing
a CL with Dk of 58 is prescribed to px, what will be best management for px
- Advise px to do and extended wear only limit to 2 or 3 nights of overnight wear
- Advise px to just wear the lens when px is awake - chatgpt
