30 Questions
How have advancements in toric soft lens design sought to improve orientation and stability characteristics?
By increasing thickness variations
What was the main issue revealed by a recent wearer survey regarding toric lenses?
Poor lens performance in terms of comfort and vision
What percentage of the ametropic population has 0.75D or more of refractive astigmatism?
Approximately 30%
What do Rigid Gas Permeable (RGP) lenses correct?
Corneal astigmatism
Which type of lenses are now available in silicone hydrogel materials according to the text?
Custom made toric soft lenses
What percentage of prescriptions have more than 1.00DC of astigmatism based on the information provided?
Approximately 16%
What should be done if the lens rotates to the left?
Add rotation
How should the axis be adjusted if the lens rotates clockwise?
Add axis
What is the consequence of a toric soft lens being 20 degrees off-axis?
Over-refraction
Why is a spherical over-refraction carried out for a toric soft lens?
To determine cylinder power adjustment
What indicates that the lens fit is adequate?
Stability of the end-point
Why should a new trial lens be inserted after compensating for cylinder axis rotation?
To allow a meaningful spherical over-refraction
Why is maintaining the rotational stability of a soft toric lens crucial?
To allow lateral eye movements without lens displacement
What is a key difference between a rigid toric lens and a soft toric lens?
Soft lenses may rotate on the eye due to reduced modulus of elasticity
What is the purpose of empirical fitting in the context of contact lenses?
To order a diagnostic lens for the patient
Why is it important for soft toric lenses to maintain stability during lateral eye movements?
To ensure consistent optical correction for astigmatic patients
What feature of a soft toric lens allows it to fit spherical corneas effectively?
The presence of a toric back surface
In soft toric fitting, what determines the success of optical correction?
The surface toricity and alignment with the cornea
What is one of the reasons for poor vision that can occur due to axis rotation?
Difference in thickness profiles of lenses
How can the problem of axis rotation leading to poor vision be avoided?
Using trial lenses that closely match the patient's ocular prescription
What does Figure 8 in the text suggest for dealing with poor visual acuity?
Assessing rotational stability of the lens in the eye
If a lens is rotationally stable but with a mislocated axis, what action should the practitioner take according to the text?
Compensate for axis rotation and reorder the lens
What is recommended if a soft toric lens is rotationally unstable?
Using a different fit or design of soft toric lens
What role does a sphere/cyl over-refraction play in determining poor visual acuity causes according to the text?
Identifying differences between labeled and actual specifications
What type of lenses were found to be ineffective for correcting low levels of astigmatism?
Aspheric soft contact lenses
Which publication discusses a new daily wear silicone hydrogel lens for astigmatism?
Spectrum, 2007; January. 39-40
In which study was a clinical evaluation done on factors influencing toric soft contact lens fit?
Optom Vis Sci, 2002; 79:1, 11-19
Which publication provides a systematic approach to problem-solving with soft toric contact lenses?
Optician, 1989; 198:5211, 16-18
Which study involved a clinical comparison of two soft toric contact lenses?
Optician, 1996; 211:5549 20-21
Which publication introduced a new dual-thin zone disposable toric lens?
Optician, 2000; 219:5736
Explore a recent survey findings on toric lens performance, highlighting areas of improvement in comfort and vision ratings. Learn about the introduction of advanced designs and silicone hydrogel materials for both stock and custom made toric soft lenses.
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