Correspondence Re: Arora et al.: Role of corneal collagen cross-linking in pseudophakic bullous keratopathy: a clinicopathological study (Ophthalmology 2013;120:2413-8) Dear Editor: We read with interest the paper from Arora et al1 regarding the effect of collagen cross-linking (CXL) on corneal edema from pseudophakic bullous keratopathy. It is known that changes of the corneal stroma resulting from CXL affect corneal hydration and that there is a transient effect of CXL on clinically significant edema.2 This manuscript confirms this clinical observation with thorough clinical investigation and histopathologic results. The authors conclude that CXL is a temporary solution for patients awaiting keratoplasty. Because the article, according to its title, deals with the role of CXL in pseudophakic bullous keratopathy, we believe a few more points should be discussed. The first is the effect of the stromal structural changes induced by CXL on subsequent penetrating keratoplasty, in particular, possible difficulties regarding suture placement and healing of the graftehost junction. Another aspect is the effect of the CXL on the antigenicity of the cornea. It has been reported that after CXL an immunogenic response may occur, often clinically resembling sterile infiltration of the cornea.3 This response may also affect the possibility for corneal rejection after keratoplasty. Many of these patients undergo endothelial keratoplasty rather than penetrating keratoplasty. Therefore, the clarity of the anterior stroma and the graftehost interface after the procedure should be addressed. It is not known whether the anterior stroma will restore its clarity after Descemet’s stripping automated endothelial keratoplasty, if along with the effect of the previous edema, there is an added effect of CXL on stromal structure. According to studies on patients with keratoconus, there is a possibility of haze formation after CXL.4 The effect in edematous corneas remains unknown. Regarding the operative procedure, it is unknown whether CXL affects the stripping of the host Descemet membrane during Descemet’s stripping automated endothelial keratoplasty. In addition, the long-term refractive effect of CXL in corneal stroma should be addressed.5 In our opinion, additional clinical investigation is needed to define the role of CXL in pseudophakic bullous keratopathy. 1,2

GEORGE D. KYMIONIS, MD, PHD GEORGE A. KONTADAKIS, MD, MSC1 1 2

Institute of Vision and Optics, University of Crete, Heraklion, Greece; Bascom Palmer Eye Institute, University of Miami, Miami, Florida

References 1. Arora R, Manudhane A, Saran RK, et al. Role of corneal collagen cross-linking in pseudophakic bullous keratopathy: a clinicopathological study. Ophthalmology 2013;120:2413–8.

2. Kontadakis GA, Ginis H, Karyotakis N, et al. In vitro effect of corneal collagen cross-linking on corneal hydration properties and stiffness. Graefes Arch Clin Exp Ophthalmol 2013;251:543–7. 3. Ghanem RC, Netto MV, Ghanem VC, et al. Peripheral sterile corneal ring infiltrate after riboflavin-UVA collagen crosslinking in keratoconus. Cornea 2012;31:702–5. 4. Raiskup F, Hoyer A, Spoerl E. Permanent corneal haze after riboflavin-UVA-induced cross-linking in keratoconus. J Refract Surg 2009;25:S824–8. 5. Hashemi H, Seyedian MA, Miraftab M, et al. Corneal collagen cross-linking with riboflavin and ultraviolet a irradiation for keratoconus: long-term results. Ophthalmology 2013;120:1515–20.

Author reply Dear Editor: We thank Kymionis et al for their valuable comments on our paper, “Role of corneal collagen cross-linking in pseudophakic bullous keratopathy: a clinicopathological study.”1 All patients with pseudophakic bullous keratopathy underwent “epi off” collagen crosslinking (CXL) in the central 8.0-mm zone of the affected cornea. Subsequent keratoplasty and suture placement, however, was not difficult; the average host trephination was 8 to 8.5 mm and sutures were placed in the untreated host cornea. Because the CXL-treated host corneas were trephined, removed, and further replaced with donor cornea, there was no question of altered immunogenic response and further additional risk of graft rejection. We agree that anterior stromal haze and scarring after CXL is a distinct possibility, but cannot comment because none of our cases underwent endothelial keratoplasty. The effect of CXL on Descemet membrane stripping during Descemet’s stripping automated endothelial keratoplasty needs to be explored.

RITU ARORA, MD ADITI MANUDHANE, MS RAVINDRA K. SARAN, MD JAWAHAR L. GOYAL, MD GAURAV GOYAL, MS DEEPA GUPTA, MS Guru Nanak Eye Centre, New Delhi, India

Reference 1. Arora R, Manudhane A, Saran RK, et al. Role of corneal collagen cross-linking in pseudophakic bullous keratopathy: a clinicopathological study. Ophthalmology 2013;120:2413–8.

Re: Coster et al.: A comparison of lamellar and penetrating keratoplasty outcomes (Ophthalmology 2014;121:979-87) Dear Editor: With interest our group read the article on clinical outcomes of lamellar versus penetrating keratoplasty by Coster et al,1 which states that between 1996 and 2013 in Australia, the results of penetrating

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