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Patient 7R in our series had trabeculectomy to controlelevated IOP prior to DSAEK. The subsequent DSAEKand cataract surgeries were pending prior to publica-tion. We do not believe the poor outcome is a conse-quence of the surgery but of the disease itself.

Four different surgeons were involved in explantingall the iris implants except in the patient who devel-oped the suprachoroidal hemorrhage. All removedthe implant in similar fashion. After making one ormore paracenteses, a dispersive OVD was placed be-hind and in front of the implant. A keratome measur-ing 3.0 mm was used to enter the eye. The surgeonused a Stern-Gill scissors (Katena Products, Inc.) ora Grieshaber single-use 25-gauge retinal scissors tocut the implant into 2 or more pieces and an MSTmicroholding forceps or a 25-gauge Grieshabersingle-use retinal forceps to carefully externalize theflexible iris implant segment through the woundwith minimal difficulty; 10-0 nylon sutures wereplaced across the wound.

Wehave includedavideoofone explantation surgery(Video, available at http://jcrsjournal.org). In addition,Eyetube.net has a narrated video of another iris implantremoval technique.AdDavid Carl Ritterband, MD,Richard Koplin, MD, Elaine Wu, MD, Ambika Hoguet,MD, Tal Raviv, MD, John Aljian, MD, John Seedor, MD

Online Video

REFERENCES1. Choyce DP. Complicatons of the AC implants of the early 1950’s

and the UGH or Ellingson syndrome of the late 1970’s. Am Intra-

Ocular Implant Soc J 1978; 4(2):22–29

2. Apple DJ, Mamalis N, Loftfield K, Googe JM, Novak LC, Kavka-

Van Norman K, Brady SE, Olson RJ. Complications of intraocular

lenses. A historical and histopathological review. Surv Ophthal-

mol 1984; 29:1–54

OTHER CITED MATERIALA. ElMallah M. Removal of a cosmetic iris prosthesis. Available

at: http://eyetube.net/video/removal-of-a-cosmetic-iris-prosthesis/.

Accessed July 3, 2012

Combination of corneal crosslinkingand intrastromal corneal ring segmentsfor the treatment of keratoconus

We would like to comment on the recent article byKılıc et al.1 Corneal crosslinking (CXL), introducedby Wollensak et al.,2 can stabilize the corneal biome-chanical properties and prevent progression in kerato-conus. As a crucial step in the CXL technique, thecorneal epithelium should be removed prior to ribofla-vin application and ultraviolet-A (UVA) exposure soriboflavin reaches the stroma and induces the desired

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crosslinking effect3; however, the postoperative painand delayed epithelial healing make this procedureunpleasant for patients.4 To avoid these disadvan-tages, an alternative procedure of riboflavin adminis-tration via an intrastromal pocket is proposed, aswas done in this study in which intrastromal cornealring segments (ICRS) were simultaneously implantedin the corneal pocket for an additive effect. This studyhas validated the efficacy of this combined treatment;however, there are no lines of evidence in the article tosupport that this combination is safer or more effectivethan CXL alone.

In the currently applied CXL procedure, the epithe-lium is removed within the intended treatment areaand riboflavin 0.1% is instilled on the corneal stromafor approximately 30minutes prior to UVA irradiationso the riboflavin can saturate the cornea with higherconcentration in the more anterior stroma. This differ-ence in concentration may explain why 65% to 70% ofUVA irradiation is absorbed in the anterior 200 mmand only 20% in the posterior 200 mm and thereforealso explain why the corneal stiffening occurs primar-ily in approximately 300 mm of the anterior stroma. Asthe biomechanical change in the keratoconic corneapresumably occurs in the anterior cornea rather thanin the posterior cornea,5 keratoconic patients canachieve optimal therapeutic outcomes with CXL asa result of the corneal stiffening in the anterior stroma.In the study by Kılıc et al., riboflavin was placed in thecornea at 80% depth; consequently, the posteriorcornea would imbibe most of the riboflavin with littlereaching the anterior stroma and the UVA irradiationwould have been absorbed in the posterior cornea pri-marily. To date, no reports have shown the anteriorstromal depth to which riboflavin can penetratewhen it is administered into a corneal pocket, norhave studies confirmed that this concentration of ribo-flavin is adequate to effect the anterior corneal stiffen-ing crucial for CXL to treat keratoconus. For thisreason, we think a well-matched control group inwhich patients have the CXL-only procedure (involv-ing the corneal pocket to administer riboflavin) shouldbe included in this study to further assess actions of thecombined and CXL-only procedures.

Riboflavin acts not only as a photosensitizer but alsoas a “shield” for the underlying ocular tissues, such asthe endothelium, iris, and crystalline lens; however, itmay act as a hazard if it couples with UVA light at thelevel of those structures as it will generate free radicals.When instilled in the corneal pocket and exposed toUVA, riboflavin may produce more free radicals dueto higher concentration at the level of the endotheliumand therefore may lead to damage to the endothelium.Although the patients in this study achieved goodvisual outcomes, this does not ensure that there is no

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endothelial damage, as improved visual acuity mayoccur with decreased endothelial cell count in CXL.6

Further studies are needed to evaluate the safety ofthis procedure.

Zhen-Yong Zhang, MDXing-Ru Zhang, MS

Shanghai, China

REFERENCES1. Kılıc‚ A, Kamburoglu G, Akıncı A. Riboflavin injection into the cor-

neal channel for combined collagen crosslinking and intrastromal

corneal ring segment implantation. J Cataract Refract Surg 2012;

38:878–883

2. Wollensak G, Spoerl E, Seiler T. Riboflavin/ultraviolet-A-induced

collagen crosslinking for the treatment of keratoconus. Am JOph-

thalmol 2003; 135:620–627

3. Baiocchi S, Mazzotta C, Cerretani D, Caporossi T, Caporossi A.

Corneal crosslinking: riboflavin concentration in corneal stroma

exposed with and without epithelium. J Cataract Refract Surg

2009; 35:893–899

4. Bakke EF, Stojanovic A, Chen X, Drolsum L. Penetration of ribo-

flavin and postoperative pain in corneal collagen crosslinking; ex-

cimer laser superficial versus mechanical full-thickness epithelial

removal. J Cataract Refract Surg 2009; 35:1363–1366

5. Kohlhaas M, Spoerl E, Schilde T, Unger G, Wittig C, Pillunat LE.

Biomechanical evidence of the distribution of cross-links in cor-

neas treated with riboflavin and ultraviolet A light. J Cataract

Refract Surg 2006; 32:279–283

6. Kymionis GD, Portaliou DM, Diakonis VF, Kounis GA,

Panagopoulou SI, Grentzelos MA. Corneal collagen cross-

linking with riboflavin and ultraviolet-A irradiation in patients with

thin corneas. Am J Ophthalmol 2012; 153:24–28

Figure 1. Circumferential superficial contraction lines run from theinner part of the ICRS.

Paradoxical central corneal steepeningafter collagen crosslinking in a casewith intrastromal corneal ring segments

We readwith interest the article by Kilic et al.1 aboutenhancing epithelium-off corneal collagen crosslink-ing (CXL) by injecting riboflavin into the intrastromalcorneal ring segment (ICRS) channels when perform-ing the 2 procedures simultaneously.

We would like to share one unusual experience thatmight relate to this type of practice. A 16-year-old manwith a strong family history of keratoconus presentedto our hospitalwith nonorthogonalwith-the-rule astig-matism compatible with early keratoconus in botheyes. The preoperative data were uncorrected distancevisual acuity (UDVA) of 20/50 in both eyes, and the re-fraction was C1.50 �3.50 � 13 Z 20/30 and C1.50�3.50 � 160 Z 20/25. In October 2008, shortened arc(120 degrees) ICRS (7.0 Intacs, Addition Technology)were implanted in the left eye followed by a similarprocedure in November of the same year in the righteye. The UDVA improved to 20/25 in both eyes, andthe refraction became C0.25 �1.00 � 15 Z 20/20 inthe right eye and C1.00 �2.00 � 153 Z 20/20 in the

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left eye. In March 2009, epithelium-off bilateral CXLwith 0.1% riboflavin and 20% dextran was performedusing a 3 mW/cm2 ultraviolet-A (UVA) device (Cost-ruzione Strumenti Oftalmici) and a 8.0 mm spot for30 minutes.

Two days later, the patient presented with loss ofvision in the left eye. A white superficial haze that ex-tended from the internal border of the nasal to the tem-poral ICRS was found. The epithelium closeduneventfully in both eyes, but no refractions couldbe obtained in the left eye during the first month. After1 month, the UDVA was 20/25 in the right eye and20/80 in the left eyere and the corrected distancevisual acuity was C0.25 �2.50 � 14 Z 20/20 and�3.50�2.25� 165Z 20/40, respectively. A circumfer-ential haze was noted in the left eye; it had contractionmarks that radiated from the ring segments (Figure 1)forming the equivalent of a dome of a cathedral(Figure 2, 1-year topography differential map), para-doxically increasing the central corneal curvature.The haze gradually decreased, and 2 years after thesurgery the UDVA was 20/20 in the right eye and20/40 in the left eye and the refraction was C0.75�2.50Z 20/20 and�1.00�6.00� 17Z 20/30, respec-tively, with 1C haze in the left eye.

The reason for this paradoxical response in the lefteye of a bilateral case remains unclear, but one hypoth-esis is that the additional riboflavin that went into theICRS channels enhanced the UVA-induced CXL tosuch an extent that it acted as a contraction ring steep-ening the central part of the cornea.A We are currentlysuturing the ring channels when performing simulta-neous ICRS implantation and CXL to prevent the un-even distribution of riboflavin across the cornealstroma. The collagen fibers are arranged circumferen-tially in the corneal periphery,2,3 and any CXL prefer-entially involving this part of the cornea may lead to

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