Toric Lenses Performance Survey

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How have advancements in toric soft lens design sought to improve orientation and stability characteristics?

By reducing thickness variations

By increasing thickness variations (correct)

By decreasing oxygen availability

By introducing silicone hydrogel materials

What was the main issue revealed by a recent wearer survey regarding toric lenses?

Lack of advanced designs in the market

Inadequate oxygen availability

Low durability of toric lenses

Poor lens performance in terms of comfort and vision (correct)

What percentage of the ametropic population has 0.75D or more of refractive astigmatism?

Less than 10%

Around 5%

Nearly 50%

Approximately 30% (correct)

What do Rigid Gas Permeable (RGP) lenses correct?

Corneal astigmatism Signup and view all the answers

Which type of lenses are now available in silicone hydrogel materials according to the text?

Custom made toric soft lenses Signup and view all the answers

What percentage of prescriptions have more than 1.00DC of astigmatism based on the information provided?

Approximately 16% Signup and view all the answers

What should be done if the lens rotates to the left?

Add rotation Signup and view all the answers

How should the axis be adjusted if the lens rotates clockwise?

Add axis Signup and view all the answers

What is the consequence of a toric soft lens being 20 degrees off-axis?

Over-refraction Signup and view all the answers

Why is a spherical over-refraction carried out for a toric soft lens?

To determine cylinder power adjustment Signup and view all the answers

What indicates that the lens fit is adequate?

Stability of the end-point Signup and view all the answers

Why should a new trial lens be inserted after compensating for cylinder axis rotation?

To allow a meaningful spherical over-refraction Signup and view all the answers

Why is maintaining the rotational stability of a soft toric lens crucial?

To allow lateral eye movements without lens displacement Signup and view all the answers

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 Signup and view all the answers

What is the purpose of empirical fitting in the context of contact lenses?

To order a diagnostic lens for the patient Signup and view all the answers

Why is it important for soft toric lenses to maintain stability during lateral eye movements?

To ensure consistent optical correction for astigmatic patients Signup and view all the answers

What feature of a soft toric lens allows it to fit spherical corneas effectively?

The presence of a toric back surface Signup and view all the answers

In soft toric fitting, what determines the success of optical correction?

The surface toricity and alignment with the cornea Signup and view all the answers

What is one of the reasons for poor vision that can occur due to axis rotation?

Difference in thickness profiles of lenses Signup and view all the answers

How can the problem of axis rotation leading to poor vision be avoided?

Using trial lenses that closely match the patient's ocular prescription Signup and view all the answers

What does Figure 8 in the text suggest for dealing with poor visual acuity?

Assessing rotational stability of the lens in the eye Signup and view all the answers

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 Signup and view all the answers

What is recommended if a soft toric lens is rotationally unstable?

Using a different fit or design of soft toric lens Signup and view all the answers

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 Signup and view all the answers

What type of lenses were found to be ineffective for correcting low levels of astigmatism?

Aspheric soft contact lenses Signup and view all the answers

Which publication discusses a new daily wear silicone hydrogel lens for astigmatism?

Spectrum, 2007; January. 39-40 Signup and view all the answers

In which study was a clinical evaluation done on factors influencing toric soft contact lens fit?

Optom Vis Sci, 2002; 79:1, 11-19 Signup and view all the answers

Which publication provides a systematic approach to problem-solving with soft toric contact lenses?

Optician, 1989; 198:5211, 16-18 Signup and view all the answers

Which study involved a clinical comparison of two soft toric contact lenses?

Optician, 1996; 211:5549 20-21 Signup and view all the answers

Which publication introduced a new dual-thin zone disposable toric lens?

Optician, 2000; 219:5736 Signup and view all the answers