Soft Toric (M1) Flashcards
Who are the best candidates for soft torics?
- poor VA with spherical soft CL
- GPs difficult to fit or not tolerated
- high sphere vs cyl (around
What is the order of choosing parameters in selecting soft toric lenses?
- cyl axis
- cyl power
- sphere power
What are the different stabilization techniques for soft torics?
- prism
- truncation
- thin zones
- peri-ballast
If the soft toric lens is rotated clockwise, does the cyl axis increase or decrease? 1. What should be done? 2
- decrease
2. add amount rotated
What are the 1 day soft toric lenses that have a periballast design?
- softlens daily disposables for astigmatism
2. clariti 1 day toric
What does the corneal toricity and lenticular astigmatism lead to?
refractive astigmatism
If poor visual acuity is found with soft torics, what should be done?
- confirm rotational stability
- compensate for stable rotation
- spherical over-refraction
- spherocyclindrical over-refraction
- recheck baseline data
- new lens
What are the disadvantages of prism ballast soft torics?
- less O2 transmissibility
- discomfort lid-lens interact
- visual problems with unilateral
What type of soft toric soft lens has thinning at the top and bottom of lens?
thin zones
What is the average cornea topography value? 1. What is the range? 2
- 7.80mm (43.25D)
2. 7.00 (48.25D) to 9.50mm (35.50D)
What are the features of “blink stabilized” lenses?
thicker zones nasal and temporal
What type of soft toric lens has a minus carrier over the entire lens an then thin superiorly with no prism in optic zone?
peri-ballast
What are the 1 day soft toric lenses that have a thin design?
- dailies aqua comfort plus for astigmatism
2. 1 day acuvue moist for astigmatism
For every 10deg of axis misalignment, how much cyl is induced?
1/3 of cyl power (in wrong meridian though)
What are the major aspects that encompass the fit assessment of a soft toric?
- centration
- movement
- orientation
- rotation
What is the first soft toric lens ordered for the patient with a vertex Rx of -3.00-3.12x180?
-3.50-2.25x180 (-2.25 is max)
If the soft toric lens is rotated counter-clockwise, does the cyl axis increase or decrease? 1. What should be done? 2
- increase
2. subtract amount rotated
How do you know the issue with the soft toric is a problem with axis based on the over-refraction?
the spherical equivalent will be plano at a random axis (cyl)
What is the amount of prism found in prism ballast? 1. What is the lens stabilized by? 2
- 0.75 to 2pd
2. thickness difference and weight (minimal)
Where does the lens marking now sit after the change in axis is made due to a rotation?
same as before change
When are soft torics most necessary?
- refractive astigmatism -0.75 or more
2. corneal toricity does NOT equal refractive astigmatism
For a truncated soft toric lens, what does the truncation line up with?
lower lid
What percentage of soft lenses are toric?
34%
If a patients spec Rx has an axis of 85, what should the axis of the soft toric be? 1. For 15deg? 2
- 90
2. 10
If the exact cylinder power is not available, what should be done?
select lower cyl power
How long should a soft toric settle before analyzing?
15min
What is the soft toric lens type that has the toricity on the back surface of the lens? 1. What type of patient is this good for? 2
- purevision for astigmatism (or ultra)
2. high corneal cyl patients
Who are not good candidates for soft torics?
- cylinder greater than sphere
2. oblique cylinders
What are the things that can lead to rotation of a soft toric?
- large diameters
- thickness differential of lens allows orientation
- blink forces
- “watermelon seed” effect
- gravity
