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Toric implantable collamer lens for keratoconus.

Kummelil MK, Hemamalini MS, Bhagali R, Sargod K, Nagappa S, Shetty R, Shetty BK - Indian J Ophthalmol (2013)

Bottom Line: Keratoconus is a progressive non-inflammatory thinning of the cornea that induces myopia and irregular astigmatism and decreases the quality of vision due to monocular diplopia, halos, or ghost images.Keratoconus patients unfit for corneal procedures and intolerant to refractive correction by spectacles or contact lenses have been implanted toric posterior chamber phakic intraocular lenses (PC pIOLs) alone or combined with other surgical procedures to correct the refractive errors associated with keratoconus as an off label procedure with special informed consent from the patients.Several reports attest to the safety and efficacy of the procedure, though the associated corneal higher order aberrations would have an impact on the final visual quality.

View Article: PubMed Central - PubMed

Affiliation: Cataract and Refractive Lens Surgery Services, Narayana Nethralaya, Post-Graduate Institute of Ophthalmology, Bangalore, Karnataka, India.

ABSTRACT
Keratoconus is a progressive non-inflammatory thinning of the cornea that induces myopia and irregular astigmatism and decreases the quality of vision due to monocular diplopia, halos, or ghost images. Keratoconus patients unfit for corneal procedures and intolerant to refractive correction by spectacles or contact lenses have been implanted toric posterior chamber phakic intraocular lenses (PC pIOLs) alone or combined with other surgical procedures to correct the refractive errors associated with keratoconus as an off label procedure with special informed consent from the patients. Several reports attest to the safety and efficacy of the procedure, though the associated corneal higher order aberrations would have an impact on the final visual quality.

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(a) Vertically spread double-pass image of the PSF of a patient with dysphotopsia post-toric pIOL despite UDVA of 6/9. (b) The doublepass (OQAS) values at different levels of contrast and visual acuity chart show poor optical quality. (C) Corresponding high values for corneal aberrations, specifically vertical coma (nZ3,mZ_1), seen in the pyramidal representation of the Zernike analysis (c/deg=cycles per degree;HOA=higher-order aberration; LOA=lower-order aberration; MTF=modulation transfer function; OQAS=Optical quality Analysis System; OSI = optical scatter index; RMS = root mean square).
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Figure 5: (a) Vertically spread double-pass image of the PSF of a patient with dysphotopsia post-toric pIOL despite UDVA of 6/9. (b) The doublepass (OQAS) values at different levels of contrast and visual acuity chart show poor optical quality. (C) Corresponding high values for corneal aberrations, specifically vertical coma (nZ3,mZ_1), seen in the pyramidal representation of the Zernike analysis (c/deg=cycles per degree;HOA=higher-order aberration; LOA=lower-order aberration; MTF=modulation transfer function; OQAS=Optical quality Analysis System; OSI = optical scatter index; RMS = root mean square).

Mentions: Secondary use of TICLs have focused on the correction of the residual refractive error after progressive keratoconus was stabilized by CXL[1314] or after management of the irregular astigmatism induced by an eccentric cone with or without adjunct CXL.[681516] These results demonstrate the complementary goals of each treatment modality. Corneal ring implantation in keratoconic eyes reshapes the abnormal cornea, thus reducing the topographic abnormalities. Corneal CXL is performed 6-12 months later to stabilize the normalized corneal shape. Finally, after another delay to allow resolution of post-CXL corneal changes, correction of the residual spherocylindrical refractive error is performed with a toric pIOL. However, the visual quality metrics after correction of the refractive error by TICLs may be affected by the inherent corneal aberrations in keratoconus [Figs. 4 and 5].[7] One possible method of predicting the eyes with significant irregular corneal astigmatism and higher order aberrations that are likely to interfere with the postoperative visual quality is to evaluate the preoperative spectacle CDVA and compare it to the rigid gas permeable CDVA.[16] Eyes with significant difference between the two are likely to have poor postoperative visual quality metrics.


Toric implantable collamer lens for keratoconus.

Kummelil MK, Hemamalini MS, Bhagali R, Sargod K, Nagappa S, Shetty R, Shetty BK - Indian J Ophthalmol (2013)

(a) Vertically spread double-pass image of the PSF of a patient with dysphotopsia post-toric pIOL despite UDVA of 6/9. (b) The doublepass (OQAS) values at different levels of contrast and visual acuity chart show poor optical quality. (C) Corresponding high values for corneal aberrations, specifically vertical coma (nZ3,mZ_1), seen in the pyramidal representation of the Zernike analysis (c/deg=cycles per degree;HOA=higher-order aberration; LOA=lower-order aberration; MTF=modulation transfer function; OQAS=Optical quality Analysis System; OSI = optical scatter index; RMS = root mean square).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC3775087&req=5

Figure 5: (a) Vertically spread double-pass image of the PSF of a patient with dysphotopsia post-toric pIOL despite UDVA of 6/9. (b) The doublepass (OQAS) values at different levels of contrast and visual acuity chart show poor optical quality. (C) Corresponding high values for corneal aberrations, specifically vertical coma (nZ3,mZ_1), seen in the pyramidal representation of the Zernike analysis (c/deg=cycles per degree;HOA=higher-order aberration; LOA=lower-order aberration; MTF=modulation transfer function; OQAS=Optical quality Analysis System; OSI = optical scatter index; RMS = root mean square).
Mentions: Secondary use of TICLs have focused on the correction of the residual refractive error after progressive keratoconus was stabilized by CXL[1314] or after management of the irregular astigmatism induced by an eccentric cone with or without adjunct CXL.[681516] These results demonstrate the complementary goals of each treatment modality. Corneal ring implantation in keratoconic eyes reshapes the abnormal cornea, thus reducing the topographic abnormalities. Corneal CXL is performed 6-12 months later to stabilize the normalized corneal shape. Finally, after another delay to allow resolution of post-CXL corneal changes, correction of the residual spherocylindrical refractive error is performed with a toric pIOL. However, the visual quality metrics after correction of the refractive error by TICLs may be affected by the inherent corneal aberrations in keratoconus [Figs. 4 and 5].[7] One possible method of predicting the eyes with significant irregular corneal astigmatism and higher order aberrations that are likely to interfere with the postoperative visual quality is to evaluate the preoperative spectacle CDVA and compare it to the rigid gas permeable CDVA.[16] Eyes with significant difference between the two are likely to have poor postoperative visual quality metrics.

Bottom Line: Keratoconus is a progressive non-inflammatory thinning of the cornea that induces myopia and irregular astigmatism and decreases the quality of vision due to monocular diplopia, halos, or ghost images.Keratoconus patients unfit for corneal procedures and intolerant to refractive correction by spectacles or contact lenses have been implanted toric posterior chamber phakic intraocular lenses (PC pIOLs) alone or combined with other surgical procedures to correct the refractive errors associated with keratoconus as an off label procedure with special informed consent from the patients.Several reports attest to the safety and efficacy of the procedure, though the associated corneal higher order aberrations would have an impact on the final visual quality.

View Article: PubMed Central - PubMed

Affiliation: Cataract and Refractive Lens Surgery Services, Narayana Nethralaya, Post-Graduate Institute of Ophthalmology, Bangalore, Karnataka, India.

ABSTRACT
Keratoconus is a progressive non-inflammatory thinning of the cornea that induces myopia and irregular astigmatism and decreases the quality of vision due to monocular diplopia, halos, or ghost images. Keratoconus patients unfit for corneal procedures and intolerant to refractive correction by spectacles or contact lenses have been implanted toric posterior chamber phakic intraocular lenses (PC pIOLs) alone or combined with other surgical procedures to correct the refractive errors associated with keratoconus as an off label procedure with special informed consent from the patients. Several reports attest to the safety and efficacy of the procedure, though the associated corneal higher order aberrations would have an impact on the final visual quality.

Show MeSH
Related in: MedlinePlus