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Several methods have been developed to address and reduce preexisting astigmatism. The refractive results associated with the use of toric IOLs are likely to be more predictable. Other advantages of toric IOL include absence of need for any additional astigmatic correction procedure during cataract surgery, faster visual recovery as well as the reversibility of the procedure. There has not been any trial carried out to evaluate the results of toric IOL in either the investigators local population or in East Asia. Hence, the investigators set out to evaluate and compare the efficacy, safety, predictability and stability of the STAAR and Alcon toric IOL in Asian eyes.
The improvements in surgical technique as well as advances in technology employed during modern cataract surgery have made it a safe procedure in routine cases. Moving forwards, the single most pressing challenge facing cataract surgeons in the developed countries today is the ability to achieve predictable and accurate refractive outcomes. Increasingly, surgeons and patients alike have come to measure the success of their surgery by the refractive outcome.
Using partial coherence interferometry has led to more accurate biometry and consequently more predictable spherical results. This also helped paved the way for satisfactory correction of presbyopia with multifocal intraocular lenses (IOL).
Astigmatism is also an important component of the refractive equation. Estimates of the incidence of significant, naturally occurring astigmatism vary widely from 7.5% to 75%1. It is thought that 3% to 15% of eyes may have 2 or more diopters (D) of astigmatism2. Many surgeons would agree that astigmatism of greater than 0.5 D will have visual consequences such as symptoms of ghosting and shadows and they now aim for both spherical and astigmatic outcomes of +/ - 0.5 D3.
Several methods have been developed to address and reduce preexisting astigmatism. While corneal relaxing incisions for astigmatic correction can be unpredictable and highly surgeon dependent, the opposite is true for toric IOLs. The refractive results associated with the use of toric IOLs are likely to be more predictable as it is independent of corneal wound healing. The implantation of an IOL is also less surgeon dependent. Other advantages associated with toric IOLs include the absence of need for any additional astigmatic correction procedure during cataract surgery, faster visual recovery as well as the reversibility of the procedure.
Studies have been carried out to evaluate the efficacy and rotational stability of the STAAR AA4203 TF/TL toric IOL since its FDA approval in November 1998. These trials have only been carried out on Caucasian eyes and have shown a significant reduction in the pre-existing refractive astigmatism, improvement of postoperative unaided visual acuity as well as excellent refractive as well as rotational stability (latter especially so with the TL model). Ruhswurm et al.6 reviewed 37 eyes with STAAR toric IOL over a mean duration of 20.3 months and found that 78.4% of eyes had residual refractive astigmatism within +/- 1.00 D and 48.6% within +/- 0.50D. 83.4% of these eyes achieved best-corrected visual acuity of 20/40 or better. Sun et al.7 demonstrated improved unaided visual outcome between eyes with toric (130 eyes; 86.4% with visual acuity 20/40 or better) and spherical IOL (51 eyes; 76% with visual acuity 20/40 or better). Similar results have also been obtained with the Alcon toric IOL. In Horn et al.9, the clinical trial results of 250 patients with Alcon toric IOL have been described, demonstrating good unaided visual acuity of 20/25 or better at the 6-month postoperative visit (66% of patients with unilateral toric implant and 97% with bilateral implants). 97% of these toric patients achieved spectacle freedom for distance vision, compared to 50% of control patients. It is well documented that the rotational stability of these toric IOL is crucial to the efficacy of astigmatic reduction. Theoretical calculations show that an estimated 1/3 of astigmatic correction is lost if the IOL is rotated by 10 degrees off axis, as well as potential worsening of preoperative astigmatism in the presence of more than 30 degrees of off-axis rotation. Toric IOL stability is dependent on multiple factors, one of which is the capsular bag size. Vass et al.11 showed a good correlation between axial length and capsular bag diameter (CBD), especially so in eyes with axial lengths of less than 25.0mm. On the other hand, highly myopic eyes are not shown to have a greater risk of having a larger CBD than those with normal axial lengths. A formula derived to calculate a predicted CBD (CBDp) showed that values greater than 10.3mm are likely to have existing larger CBD and hence benefit from implantation of longer toric IOL due to better centration.
To date, there has not been any trial carried out to evaluate the results of toric IOL in either our local population or in East Asia. There has also not been any prospective clinical trial conducted to compare the difference (if any) between a plate-haptic and loop-haptic toric IOL. Hence, we set out to evaluate and compare the efficacy, safety, predictability and stability of the STAAR and Alcon toric IOL in Asian eyes.
Allocation: Randomized, Control: Uncontrolled, Endpoint Classification: Safety/Efficacy Study, Intervention Model: Parallel Assignment, Masking: Single Blind, Primary Purpose: Treatment
Phacoemulsification with implantation of toric IOL
Singapore National Eye Centre
Singapore National Eye Centre
Published on BioPortfolio: 2014-08-27T03:13:46-0400
The recently introduced toric V4c toric ICL (STAAR Surgical Company, Monrovia, CA, USA) has been designed with a 360-µm central hole to allow aqueous humor to flow without the need for an...
Study evaluates the visual outcomes and patient satisfaction after implantation of a toric intraocular lens (IOL).
This was a prospective, double-masked, 15-month clinical trial comparing efficacy of phacoemulsification alone to combined phacoemulsification and implantation of the iStent® trabecular m...
The aim of this study is to evaluate the visual function of patients with bilateral implantation of the IOL trifocal ZEISS AT LISA TRI TORIC by means of visual acuity tests with and withou...
The objective of this study is to evaluate the postoperative visual function of Taiwanese patients following bilateral or unilateral AcrySof Toric Intraocular Lens (IOL) implantation.
To evaluate the cost-effectiveness of toric versus monofocal intraocular lens (IOL) implantation in cataract patients with bilateral corneal astigmatism.
To evaluate the long-term changes in endothelial cell density (ECD) after the implantation of two types of foldable iris-fixated phakic intraocular lenses (pIOLs) for the treatment of myopia and astig...
To determine whether any of three keratometry devices is superior to the others in predicting the ideal toric intraocular lens (IOL) alignment meridian.
To compare the amount of phacoemulsification ultrasound energy used between eyes undergoing femtosecond laser-assisted cataract surgery (FLACS) and conventional phacoemulsification.
Research development on blastocyst implantation was reviewed in three sections: primate implantation, ungulate farm animal implantation, and the general process of blastocyst implantation in small rod...
Endometrial implantation of EMBRYO, MAMMALIAN at the BLASTOCYST stage.
Delay in the attachment and implantation of BLASTOCYST to the uterine ENDOMETRIUM. The blastocyst remains unattached beyond the normal duration thus delaying embryonic development.
Means of postcoital intervention to avoid pregnancy, such as the administration of POSTCOITAL CONTRACEPTIVES to prevent FERTILIZATION of an egg or implantation of a fertilized egg (OVUM IMPLANTATION).
Surgical insertion of an appliance for the replacement of areas of the maxilla, mandible, and face. When only portions of the mandible are replaced, it is referred to as MANDIBULAR PROSTHESIS IMPLANTATION.
The making of a continuous circular tear in the anterior capsule during cataract surgery in order to allow expression or phacoemulsification of the nucleus of the lens. (Dorland, 28th ed)
Ophthalmology is the branch of medicine that is devoted to the study and treatment of eye diseases. As well as mild visual defects correctable by lenses, ophthalmology is concerned with glaucoma, uveitis and other serious conditions affecting the eye, ...
Surgery is a technology consisting of a physical intervention on tissues. All forms of surgery are considered invasive procedures; so-called "noninvasive surgery" usually refers to an excision that does not penetrate the structure being exci...