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Reply: Corneal hydrops after intrastromal corneal ring segment implantation
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Corneal hydrops after intrastromal corneal ring segment implantation Although the imaging quality in the article by G€ uell at el.1 is limited, the corneal topography shows an increase in elevation values inferiorly and superotemporally, steepening in the inferior segment in the keratometric map, and peripheral thinning in the pachymetric map; these are more prominent in the left eye. The topographic pattern may be compatible with peripheral thinning disorders rather than keratoconus.2,3 Multiple pachymetric measurements are needed to determine the minimum thickness of the planned tunnel site prior to intrastromal corneal ring segment (ICRS) implantation. G€ uell at el. planned ICRS implantation at 400 mm depth; however, they did not mention how they obtained this value. The central corneal thickness (457 mm) was reported, but pachymetric value at the tunnel site, which is crucial for the ophthalmologist to perform this procedure, is not reported. Topographic pachymetry in the left eye was below 300 mm, especially at the 6 o'clock position. Briefly, in the article there is no evidence of how the authors determined the adequate implantation depth; therefore, there is the possibility of corneal perforation. However, the authors checked whether there was perforation into the anterior chamber by injecting saline solution through the stromal tunnel, proving that there was no perforation. Considering the topographic findings, we think this case is more suggestive of a peripheral thinning disease of the cornea that increases corneal fragility than of keratoconus. Vedat Kaya, MD Pelin Kaynak, MD Berna Basarir, MD Istanbul, Turkey
REFERENCES €ell JL, Verdaguer P, Elies D, Gris O, Manero F. Acute corneal 1. Gu hydrops after intrastromal corneal ring segment implantation for keratoconus. J Cataract Refract Surg 2012; 38:2192–2195 2. Karabatsas CH, Cook SD. Topographic analysis in pellucid marginal corneal degeneration and keratoglobus. Eye 1996; 10:451– 455. Available at: http://www.nature.com/eye/journal/v10/n4/pdf/ eye199699a.pdf. Accessed February 23. 2013 3. Ku JYF, Grupcheva CN, Fisk MJ, McGhee CNJ. Keratoglobus and posterior subcapsular cataract: surgical considerations and in vivo microstructural analysis. J Cataract Refract Surg 2004; 30:237–242
Reply : Although in our experience it is sometimes difficult to be sure about the differential diagnosis of corneal thinning disorders, we think that in 816
Q 2013 ASCRS and ESCRS Published by Elsevier Inc.
this case the datadasymmetric curvature superior/ inferior in the keratometric map (I-S index) with a high mean dioptric power especially in the center, inferiorly displaced anterior and posterior elevation maps, and a characteristic thickness distribution (more significant at the inferior midperiphery than at the periphery)dstrongly satisfy the requisites for keratoconus. Our therapeutic approach of ICRS implantation in a nonprogressive clinical situation would have been the same even if the keratoconus diagnosis had not been clear. As a standard and similar to most corneal surgeons, we evaluated the focal local thickness during the surgery with the ultrasonic probe. It was thicker than 500 mm at the incision area and the sites where the segments were to be implanted. We usually work at 80% depth at the incision site, which is why we worked at 400 mm. This was the first time we confronted these complications after a significant number of years of experience with ICRS implantation in corneal thinning disorders, and we agree with Kaya et al. that at least theoretically, perforation and/or a break at the Descemet membrane level would be more common than keratoconus in peripheral thinning disorders.dJose L. G€ uell, MD, PhD, Paula Verdaguer, MD, Daniel Elies, MD, Oscar Gris, MD, PhD, Felicidad Manero, MD
Further assessment of visual results with accommodating intraocular lenses versus mini-monovision The study by Beiko1 compared near vision and quality of vision after controlling for pseudoaccommodation in patients with single-optic accommodating intraocular lenses (IOLs) or monofocal IOLs targeted for mini-monovision. The author has performed an excellent clinical study despite the fact that accommodating IOLs have been highly praised by many cataract surgeons in developed countries, even in some developing countries. The study told us that single-optic accommodating IOLs did not offer a significant advantage in near visual acuity over mini-monovision with a monofocal (nonaccommodating) IOL. In our opinion, some modifications would make the study even better. First, the study emphasized pseudoaccommodation, which Beiko claimed is seen in most postoperative patients after cataract removal and standard monofocal IOL implantation. Including a group of patients with monofocal IOLs without a monovision design added would clarify whether accommodating IOLs have clinically significant accommodation. Second, modified monovision (nondominant eye set for 0.5 to 1.0 diopter [D]) was preferred by many 0886-3350/$ - see front matter http://dx.doi.org/10.1016/j.jcrs.2013.03.011
Corneal hydrops after intrastromal corneal ring segment implantation Although the imaging quality in the article by G€ uell at el.1 is limited, the corneal topography shows an increase in elevation values inferiorly and superotemporally, steepening in the inferior segment in the keratometric map, and peripheral thinning in the pachymetric map; these are more prominent in the left eye. The topographic pattern may be compatible with peripheral thinning disorders rather than keratoconus.2,3 Multiple pachymetric measurements are needed to determine the minimum thickness of the planned tunnel site prior to intrastromal corneal ring segment (ICRS) implantation. G€ uell at el. planned ICRS implantation at 400 mm depth; however, they did not mention how they obtained this value. The central corneal thickness (457 mm) was reported, but pachymetric value at the tunnel site, which is crucial for the ophthalmologist to perform this procedure, is not reported. Topographic pachymetry in the left eye was below 300 mm, especially at the 6 o'clock position. Briefly, in the article there is no evidence of how the authors determined the adequate implantation depth; therefore, there is the possibility of corneal perforation. However, the authors checked whether there was perforation into the anterior chamber by injecting saline solution through the stromal tunnel, proving that there was no perforation. Considering the topographic findings, we think this case is more suggestive of a peripheral thinning disease of the cornea that increases corneal fragility than of keratoconus. Vedat Kaya, MD Pelin Kaynak, MD Berna Basarir, MD Istanbul, Turkey
REFERENCES €ell JL, Verdaguer P, Elies D, Gris O, Manero F. Acute corneal 1. Gu hydrops after intrastromal corneal ring segment implantation for keratoconus. J Cataract Refract Surg 2012; 38:2192–2195 2. Karabatsas CH, Cook SD. Topographic analysis in pellucid marginal corneal degeneration and keratoglobus. Eye 1996; 10:451– 455. Available at: http://www.nature.com/eye/journal/v10/n4/pdf/ eye199699a.pdf. Accessed February 23. 2013 3. Ku JYF, Grupcheva CN, Fisk MJ, McGhee CNJ. Keratoglobus and posterior subcapsular cataract: surgical considerations and in vivo microstructural analysis. J Cataract Refract Surg 2004; 30:237–242
Reply : Although in our experience it is sometimes difficult to be sure about the differential diagnosis of corneal thinning disorders, we think that in 816
Q 2013 ASCRS and ESCRS Published by Elsevier Inc.
this case the datadasymmetric curvature superior/ inferior in the keratometric map (I-S index) with a high mean dioptric power especially in the center, inferiorly displaced anterior and posterior elevation maps, and a characteristic thickness distribution (more significant at the inferior midperiphery than at the periphery)dstrongly satisfy the requisites for keratoconus. Our therapeutic approach of ICRS implantation in a nonprogressive clinical situation would have been the same even if the keratoconus diagnosis had not been clear. As a standard and similar to most corneal surgeons, we evaluated the focal local thickness during the surgery with the ultrasonic probe. It was thicker than 500 mm at the incision area and the sites where the segments were to be implanted. We usually work at 80% depth at the incision site, which is why we worked at 400 mm. This was the first time we confronted these complications after a significant number of years of experience with ICRS implantation in corneal thinning disorders, and we agree with Kaya et al. that at least theoretically, perforation and/or a break at the Descemet membrane level would be more common than keratoconus in peripheral thinning disorders.dJose L. G€ uell, MD, PhD, Paula Verdaguer, MD, Daniel Elies, MD, Oscar Gris, MD, PhD, Felicidad Manero, MD
Further assessment of visual results with accommodating intraocular lenses versus mini-monovision The study by Beiko1 compared near vision and quality of vision after controlling for pseudoaccommodation in patients with single-optic accommodating intraocular lenses (IOLs) or monofocal IOLs targeted for mini-monovision. The author has performed an excellent clinical study despite the fact that accommodating IOLs have been highly praised by many cataract surgeons in developed countries, even in some developing countries. The study told us that single-optic accommodating IOLs did not offer a significant advantage in near visual acuity over mini-monovision with a monofocal (nonaccommodating) IOL. In our opinion, some modifications would make the study even better. First, the study emphasized pseudoaccommodation, which Beiko claimed is seen in most postoperative patients after cataract removal and standard monofocal IOL implantation. Including a group of patients with monofocal IOLs without a monovision design added would clarify whether accommodating IOLs have clinically significant accommodation. Second, modified monovision (nondominant eye set for 0.5 to 1.0 diopter [D]) was preferred by many 0886-3350/$ - see front matter http://dx.doi.org/10.1016/j.jcrs.2013.03.011