Torische Intraokularlinse zur Korrektur eines höhergradigen Astigmatismus nach Keratoplastik bei Pseudophakie - eine Kasuistik1

Tehrani, Mehdi Hosseini; Schwenn, Oliver; Dick, Hb B.

doi:10.1055/s-2001-19690

Cited by 20 publications

(7 citation statements)

References 8 publications

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“…The site of arcuate keratotomy can be either in the donor cornea 1,2,4,7 or at the interface of the graft and the host cornea. 3,11,12 Until now, incisions in the host cornea have not been Cyl D Z astigmatic dioptric power; Sim K Z simulated keratometry recommended for the treatment of post-keratoplasty astigmatism. Refractive interventions in the recipient's cornea were reputed to be ineffective because it was believed that the scarring, which resulted at the graft-host junction, changed the biomechanical state of the cornea.…”

Section: Discussionmentioning

confidence: 99%

Correction of post-keratoplasty astigmatism with keratotomies in the host cornea

Bochmann

Schipper

2006

Journal of Cataract and Refractive Surgery

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We evaluated the effects of astigmatic keratotomy performed in the host cornea to treat astigmatism after penetrating keratoplasty. In 11 patients with high post-keratoplasty astigmatisms (mean 9.02 diopters [D]; range 5.5 to 17.4 D), an arcuate keratotomy was performed in the host cornea. The mean incision depth was 575 mum (range 500 to 600 mum). The refractive data were analyzed using the Alpins method for vector analysis. The mean keratometric cylinder decreased to 3.41 D (range 0.9 to 5.3 D). The mean surgically induced astigmatism achieved was 7.3 +/- 3.89, with a mean correction index of 0.82 +/- 0.34. No microperforations were observed, and neither graft decompensation nor rejection occurred. Astigmatic keratotomy performed in the host cornea was a safe procedure to reduce post-keratoplasty astigmatism. The procedure offers the potential for correction of the astigmatism and has satisfactory predictability.

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Section: Discussionmentioning

confidence: 99%

Correction of post-keratoplasty astigmatism with keratotomies in the host cornea

Bochmann

Schipper

2006

Journal of Cataract and Refractive Surgery

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“…Tehrani et al 10,11 describe the use of toric iris-fixated phakic IOLs in phakic or pseudophakic eyes. In our case, this was not possible as the refractive range of the iris-fixated IOLs does not include the amount of cylinder we needed.…”

Section: Discussionmentioning

confidence: 99%

“…Apart from spectacle or contact lens correction, secondary intraocular lens (IOL) implantation by transscleral fixation of a posterior chamber IOL, iris fixation of an Artisan/Verisyse (Ophtec) IOL, or implantation of an anterior chamber angle-supported IOL are currently available. [1][2][3][4][5][6][7][8][9][10][11] The situation is complicated when the aphakic patient has additional pathology, such as high postkeratoplasty astigmatism. 6,7,[10][11][12] Toric contact lenses would be the simple solution but are sometimes difficult to fit or not tolerated.…”

mentioning

confidence: 99%

Transscleral fixation of a toric intraocular lens to correct aphakic keratoplasty with high astigmatism

Borkenstein

Reuland

Limberger

et al. 2009

Journal of Cataract and Refractive Surgery

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A 71-year-old man with penetrating keratoplasty (PKP) and aphakia in the right eye and a preoperative refraction of +20.0 -11.0 x 38 and logMAR visual acuity of 20/60 presented to our hospital. The capsular support was absent because of previous complicated intracapsular cataract extraction. The implanted IOL was a custom-made Rayner 570T with +20.5 diopters (D) sphere and +11.0 D cylinder. The IOL's special haptics allowed it to be safely fixated in the sagittal plane. The postoperative refraction was +1.0 -2.0 x 5 with logMAR acuity of 20/60. Follow-up of 2 years revealed no IOL decentration. Transscleral fixation of a toric IOL requires exact outlining. Our case shows that this is possible and can result in improved visual rehabilitation.

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“…These values should be directly entered into the calculation scheme instead of the preoperative corneal shape data. Toric intraocular lenses are commonly used for correction of high or excessive postkeratoplasty astigmatism [74][75][76][77][78][79].…”

Section: Selection Of the Appropriate Toric Lensmentioning

confidence: 99%

Raytracing

2008

Mathematical Tools in Computer Graphics With C# Implementations

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Background and Purpose: Especially after corneal surgery the lateral magnification of the eye providing the retinal image size of an object is a crucial factor influencing visual acuity and binocularity. The purpose of this study is to describe a paraxial computing scheme calculating lateral magnification changes (ratio of the image sizes before and after surgery) due to variation in corneal shape and spectacle refraction. Calculation strategy: From the 4 • 4 refraction and translation matrices the system matrix representing the entire 'optical system eye' and the pupil matrix describing the subsystem from the spectacle correction to the aperture stop were defined for the state before and after surgery. As the chief ray is assumed to pass through the centre of the aperture stop, the 2 • 2 matrix of the lateral magnification ratio from preoperative to postoperative is described by the 2 • 2 sub-matrices of the respective pupil matrices. The cardinal meridians can be extracted by calculating the eigenvalues and eigenvectors. Working example: Vertex distance 14 mm, measured distance between corneal apex and aperture stop 3.6 mm, keratometry 39 D + 6 D/0°to 47 D + 3 D/30°and refraction 3.5 D À 5 À 5 D/5°to À4.0 D À 3.5 D/25°preoperatively to postoperatively. The matrix of magnification ratio from preop to postop yields (0.8960 À0.0085;0.0074 0.9371) and the eigenvalues decomposition provided a 10.7% minified image at 170.1°and a minified image of 6.1% at 78.7°, which both are clinically relevant. Conclusion: We presented a straightforward computer-based strategy for calculation of retinal image size changes using 4 • 4 matrix notation. With this model the meridional changes in lateral magnification from the preoperative to the postoperative stage or between follow-up stages can be estimated from keratometry, refraction, vertex distance and anterior chamber depth, which might be important for binocularity and vision tests in corneal surgery.

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Torische Intraokularlinse zur Korrektur eines höhergradigen Astigmatismus nach Keratoplastik bei Pseudophakie - eine Kasuistik1

Abstract: Implantation of a toric intraocular lens in pseudophakic eyes allows the correction of high astigmatism after penetrating keratoplasty. The advantage of this method compared to the keratorefractive options lies in its minor manipulation on the allograft.

Cited by 20 publications

References 8 publications

Correction of post-keratoplasty astigmatism with keratotomies in the host cornea

Correction of post-keratoplasty astigmatism with keratotomies in the host cornea

Transscleral fixation of a toric intraocular lens to correct aphakic keratoplasty with high astigmatism

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