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Corneal collagen crosslinking and herpetic keratitis
LETTERS
using the Camellin formula2 when the patient clinical history is unknown.1 With the Camellin formula, it is possible to calculate the radius of curvature of the posterior corneal surface based on the measurement of the curvature radius of the anterior corneal surface, corneal pachymetry, and a series of pachymetry measurements performed in a 3.0 mm circular zone.1 It then is possible to obtain the relative keratometric refractive index without knowing the surgically induced refractive change. Therefore, unless we have misunderstood this, the Camellin–Calossi formula does not always require preoperative data.d Megumi Saiki, PhD, Kazuno Negishi, MD, Naoko Kato, MD, Rika Ogino, Hiroyuki Arai, MD, Ikuko Toda, MD, Murat Dogru, MD, Kazuo Tsubota, MD REFERENCES 1. Camellin M, Calossi A. A new formula for intraocular lens power calculation after refractive corneal surgery. J Refract Surg 2006; 22:187–199 2. Camellin M. Proposed formula for the dioptric power evaluation of the posterior corneal surface. Refract Corneal Surg 1990; 6: 261–264
Corneal collagen crosslinking and herpetic keratitis In their recent case report, Ferrari et al.1 analyzed the case of a 30-year-old woman who had corneal collagen crosslinking (CXL) for the management of recurrent herpetic keratitis. The intervention was unsuccessful, and 15 days after the initial treatment, tectonic penetrating keratoplasty was required due to excessive thinning and melting. It is known that herpes simplex virus (HSV) reactivation is triggered by a variety of factors such as stress, immunosuppression, and laser surgery. Presumably, the use of ultraviolet-A light is a stimulus for the virus, as the authors mention, and therefore CXL does not always represent a treatment option for this kind of infection. Most important, there are 2 cases in the literature (Kymionis et al.2 and Yuksel et al.3) that describe the occurrence of herpetic keratitis following CXL treatment for progressive keratoconus. In both cases, there was no history of HSV and topical and oral treatments were required to control the infection. Therefore, even though CXL has been proposed as an alternative treatment for infectious keratitis,4 it should be applied in specific cases, not in every case independent of the underlying cause of the infection. To support this argument, there are no reports demonstrating treatment of herpetic keratitis with CXL.
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Careful patient selection is of extreme importance, especially when testing a relatively new technique, to minimize possible complications and provide a satisfying result. George D. Kymionis, MD, PhD Dimitra M. Portaliou, MD Heraklion, Crete, Greece REFERENCES M, Rama P. Impending corneal perfo1. Ferrari G, Iuliano L, Vigano ration after collagen crosslinking for herpetic keratitis. J Cataract Refract Surg 2013; 39:638–641 2. Kymionis GD, Portaliou DM, Bouzoukis DI, Suh LH, Pallikaris AI, Markomanolakis M, Yoo SH. Herpetic keratitis with iritis after corneal crosslinking with riboflavin and ultraviolet A for keratoconus. J Cataract Refract Surg 2007; 33:1982–1984 3. Yuksel N, Bilgihan K, Hondur AM. Herpetic keratitis after corneal collagen cross-linking with riboflavin and ultraviolet-A for progressive keratoconus. Int Ophthalmol 2011; 31:513–515 4. Iseli HP, Thiel MA, Hafezi F, Kampmeier J, Seiler T. Ultraviolet A/ riboflavin corneal cross-linking for infectious keratitis associated with corneal melts. Cornea 2008; 27:590–594
Reply : We thank Dr. Kymionis and Dr. Portaliou for their insightful comments and fully agree with what they say. Our case is different from the 2 previously described (Kymionis et al. and Yuksel et al.), since herpetic keratitis did not appear de novo after treatment, triggered as Kymionis and Portaliou suggest by UVA exposure, but was already present. We imagine that the colleague who treated our patient decided to use crosslinking in this case, based on the reported effects of this procedure. He probably aimed to kill the virus, stop melting, and strengthen the stroma, thus preventing perforation. However, we should bear in mind that CXL transitorily deprives the corneal tissue of cells and nerves, although we cannot exclude a positive effect on matrix metalloproteinase and inflammatory cells. Yet, in this case the effect of CXL on the inflammatory reaction was unbalanced and predisposed to the progression of melting and subsequent perforation, instead of preventing or treating it. Hence, we thank Dr. Kymionis and Dr. Portaliou for this opportunity to stress once again that CXL should be evaluated carefully when deciding to treat new diseases, as in our case.dGiulio Ferrari, MD, Lorenzo Iuliano, MD, Maurizia Vigano, MD, Paolo Rama, MD
Hydroimplantation of intraocular lenses We read with interest and some concern the recent article by Qazi et al.1 The authors suggest performing intraocular lens (IOL) implantation under
J CATARACT REFRACT SURG - VOL 39, AUGUST 2013
using the Camellin formula2 when the patient clinical history is unknown.1 With the Camellin formula, it is possible to calculate the radius of curvature of the posterior corneal surface based on the measurement of the curvature radius of the anterior corneal surface, corneal pachymetry, and a series of pachymetry measurements performed in a 3.0 mm circular zone.1 It then is possible to obtain the relative keratometric refractive index without knowing the surgically induced refractive change. Therefore, unless we have misunderstood this, the Camellin–Calossi formula does not always require preoperative data.d Megumi Saiki, PhD, Kazuno Negishi, MD, Naoko Kato, MD, Rika Ogino, Hiroyuki Arai, MD, Ikuko Toda, MD, Murat Dogru, MD, Kazuo Tsubota, MD REFERENCES 1. Camellin M, Calossi A. A new formula for intraocular lens power calculation after refractive corneal surgery. J Refract Surg 2006; 22:187–199 2. Camellin M. Proposed formula for the dioptric power evaluation of the posterior corneal surface. Refract Corneal Surg 1990; 6: 261–264
Corneal collagen crosslinking and herpetic keratitis In their recent case report, Ferrari et al.1 analyzed the case of a 30-year-old woman who had corneal collagen crosslinking (CXL) for the management of recurrent herpetic keratitis. The intervention was unsuccessful, and 15 days after the initial treatment, tectonic penetrating keratoplasty was required due to excessive thinning and melting. It is known that herpes simplex virus (HSV) reactivation is triggered by a variety of factors such as stress, immunosuppression, and laser surgery. Presumably, the use of ultraviolet-A light is a stimulus for the virus, as the authors mention, and therefore CXL does not always represent a treatment option for this kind of infection. Most important, there are 2 cases in the literature (Kymionis et al.2 and Yuksel et al.3) that describe the occurrence of herpetic keratitis following CXL treatment for progressive keratoconus. In both cases, there was no history of HSV and topical and oral treatments were required to control the infection. Therefore, even though CXL has been proposed as an alternative treatment for infectious keratitis,4 it should be applied in specific cases, not in every case independent of the underlying cause of the infection. To support this argument, there are no reports demonstrating treatment of herpetic keratitis with CXL.
1281
Careful patient selection is of extreme importance, especially when testing a relatively new technique, to minimize possible complications and provide a satisfying result. George D. Kymionis, MD, PhD Dimitra M. Portaliou, MD Heraklion, Crete, Greece REFERENCES M, Rama P. Impending corneal perfo1. Ferrari G, Iuliano L, Vigano ration after collagen crosslinking for herpetic keratitis. J Cataract Refract Surg 2013; 39:638–641 2. Kymionis GD, Portaliou DM, Bouzoukis DI, Suh LH, Pallikaris AI, Markomanolakis M, Yoo SH. Herpetic keratitis with iritis after corneal crosslinking with riboflavin and ultraviolet A for keratoconus. J Cataract Refract Surg 2007; 33:1982–1984 3. Yuksel N, Bilgihan K, Hondur AM. Herpetic keratitis after corneal collagen cross-linking with riboflavin and ultraviolet-A for progressive keratoconus. Int Ophthalmol 2011; 31:513–515 4. Iseli HP, Thiel MA, Hafezi F, Kampmeier J, Seiler T. Ultraviolet A/ riboflavin corneal cross-linking for infectious keratitis associated with corneal melts. Cornea 2008; 27:590–594
Reply : We thank Dr. Kymionis and Dr. Portaliou for their insightful comments and fully agree with what they say. Our case is different from the 2 previously described (Kymionis et al. and Yuksel et al.), since herpetic keratitis did not appear de novo after treatment, triggered as Kymionis and Portaliou suggest by UVA exposure, but was already present. We imagine that the colleague who treated our patient decided to use crosslinking in this case, based on the reported effects of this procedure. He probably aimed to kill the virus, stop melting, and strengthen the stroma, thus preventing perforation. However, we should bear in mind that CXL transitorily deprives the corneal tissue of cells and nerves, although we cannot exclude a positive effect on matrix metalloproteinase and inflammatory cells. Yet, in this case the effect of CXL on the inflammatory reaction was unbalanced and predisposed to the progression of melting and subsequent perforation, instead of preventing or treating it. Hence, we thank Dr. Kymionis and Dr. Portaliou for this opportunity to stress once again that CXL should be evaluated carefully when deciding to treat new diseases, as in our case.dGiulio Ferrari, MD, Lorenzo Iuliano, MD, Maurizia Vigano, MD, Paolo Rama, MD
Hydroimplantation of intraocular lenses We read with interest and some concern the recent article by Qazi et al.1 The authors suggest performing intraocular lens (IOL) implantation under
J CATARACT REFRACT SURG - VOL 39, AUGUST 2013