Assessing the Astigmatism Reducing Effect With Toric IOLs in Eyeswith Low Astigmatism

Study Overview
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Brief Summary
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Comparison of the astigmatism reducing effect of a toric IOL with a non toric IOL in eyes with low corneal astigmatism.

Detailed Description
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With increasing demands of patients concerning refractive outcome after cataract surgery, toric intraocular lenses (IOLs) that correct corneal astigmatism have been introduced more widely to cataract surgery. Originally, toric IOLs were used mainly for patients with high degrees of astigmatism. Since a couple of years, toric IOLs are available from numerous manufacturers to correct moderate amounts of astigmatism which are much more prevalent with about 8% having a corneal astigmatism of 2.0D or more in the cataract population. 5Using toric IOLs for these eyes results in less spectacle dependence of patients due to the astigmatic correction. Other astigmatism reducing techniques, such as peripheral corneal relaxing incisions and opposite clear corneal incisions were shown to be less predictable. Although the use of toric IOLs became the gold standard to correct corneal astigmatism during cataract surgery , there is still uncertainty, if low astigmatism should be corrected. Visser et al. showed that moderate astigmatism of than 1.5D should be corrected for monofocal IOLs and Hayashi showed that remaining astigmatism of 1.0D already decreases visual quality in eyes with multifocal IOLs. Although correction of low corneal astigmatism appears to be beneficial, some hurdles have to be taken into account. In eyes with low corneal astigmatism the accuracy of measuring the astigmatism meridian is relatively low. Furthermore, different corneal measurement techniques are not always comparable and it is difficult to know, which device shows the correct amount of astigmatism. Additionally, the correction of the spherical equivalent is of high importance, as a refractive surprise will also attenuate the astigmatism reducing effect of the toric IOL. Aim of this study is to assess, if toric IOLs are useful in patients with low amounts of corneal astigmatism and to quantify the sources of error in toric IOL power calculation.

Official Title
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Assessing the Astigmatism Reducing Effect With Toric IOLs in Eyeswith Low Astigmatism

Conditions
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Cataract, Astigmatism

Intervention / Treatment
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* Procedure: toric intraocular lens
* Procedure: non toric intraocular lens


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: cataract Age 21 and older Regular corneal astigmatism 0.5D up to 1.5 D and difference between eyes not more than 0.75D written informed consent prior to surgery Exclusion Criteria: relevant other ophthalmic diseases such as: pseudoexfoliation, glaucoma, traumatic cataract corneal scars, and other co-morbidity that could affect capsule bag stability ( e.g. Marfan syndrome) Irregular corneal astigmatism on corneal topography In case of pregnancy (pregnancy test will be taken preoperatively in women of reproductive age)

Ages Eligible for Study
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Minimum Age: 21 Years
Maximum Age: 100 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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No

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Treatment
Allocation: Randomized
Intervention Model: Parallel Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Active Comparator: Toric intraocular lens (IOL)<br>toric intraocular lens for low astigmatism correction | Procedure: toric intraocular lens<br>* cataract surgery with implantation of an toric intraocular lens<br>|
| Sham Comparator: Non toric intraocular lens (IOL)<br>non toric intraocular lens | Procedure: non toric intraocular lens<br>* cataract surgery with implantation of a non toric intraocular lens<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Subjective refraction to detect remaining astigmatism (in Diopters) between both groups |  | 12 months | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Biometrical measurement of axial length (in mm), anterior chamber depth (in mm), corneal astigmatism (radii and axial degrees) |  | 12 months | 
| Purkinjemeter measurement of Tilt (in degrees) and Decentration (in degrees) of the intraocular lens |  | 12 months | 
| Wavefront analysis of high order aberrations (root mean square, in microns) |  | 12 months | 
| Questionnaire to asses patients subjective satisfaction with visual outcome | In the questionnaire the patient has to choose if different tasks (e.g. reading, driving, watching TV) are easier for him/ her with the right eye, the left eye, or if there is no difference between both eyes | 12 months | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Cataract, Low Astigmatism