- Email: [email protected]
Paradoxical central corneal steepening after collagen crosslinking in a case with intrastromal corneal ring segments
LETTERS
endothelial damage, as improved visual acuity may occur with decreased endothelial cell count in CXL.6 Further studies are needed to evaluate the safety of this procedure. Zhen-Yong Zhang, MD Xing-Ru Zhang, MS Shanghai, China REFERENCES 1. Kılıc‚ A, Kamburoglu G, Akıncı A. Riboflavin injection into the corneal 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 J Ophthalmol 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 riboflavin and postoperative pain in corneal collagen crosslinking; excimer 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 corneas 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 crosslinking with riboflavin and ultraviolet-A irradiation in patients with thin corneas. Am J Ophthalmol 2012; 153:24–28
Paradoxical central corneal steepening after collagen crosslinking in a case with intrastromal corneal ring segments We read with interest the article by Kilic¸ et al.1 about enhancing epithelium-off corneal collagen crosslinking (CXL) by injecting riboflavin into the intrastromal corneal ring segment (ICRS) channels when performing the 2 procedures simultaneously. We would like to share one unusual experience that might relate to this type of practice. A 16-year-old man with a strong family history of keratoconus presented to our hospital with nonorthogonal with-the-rule astigmatism compatible with early keratoconus in both eyes. The preoperative data were uncorrected distance visual acuity (UDVA) of 20/50 in both eyes, and the refraction 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 similar procedure in November of the same year in the right eye. The UDVA improved to 20/25 in both eyes, and the refraction became C0.25 1.00 15 Z 20/20 in the right eye and C1.00 2.00 153 Z 20/20 in the
1879
left eye. In March 2009, epithelium-off bilateral CXL with 0.1% riboflavin and 20% dextran was performed using a 3 mW/cm2 ultraviolet-A (UVA) device (Costruzione Strumenti Oftalmici) and a 8.0 mm spot for 30 minutes. Two days later, the patient presented with loss of vision in the left eye. A white superficial haze that extended from the internal border of the nasal to the temporal ICRS was found. The epithelium closed uneventfully in both eyes, but no refractions could be obtained in the left eye during the first month. After 1 month, the UDVA was 20/25 in the right eye and 20/80 in the left eyere and the corrected distance visual acuity was C0.25 2.50 14 Z 20/20 and 3.50 2.25 165 Z 20/40, respectively. A circumferential haze was noted in the left eye; it had contraction marks that radiated from the ring segments (Figure 1) forming the equivalent of a dome of a cathedral (Figure 2, 1-year topography differential map), paradoxically increasing the central corneal curvature. The haze gradually decreased, and 2 years after the surgery the UDVA was 20/20 in the right eye and 20/40 in the left eye and the refraction was C0.75 2.50 Z 20/20 and 1.00 6.00 17 Z 20/30, respectively, with 1C haze in the left eye. The reason for this paradoxical response in the left eye of a bilateral case remains unclear, but one hypothesis is that the additional riboflavin that went into the ICRS channels enhanced the UVA-induced CXL to such an extent that it acted as a contraction ring steepening the central part of the cornea.A We are currently suturing the ring channels when performing simultaneous ICRS implantation and CXL to prevent the uneven distribution of riboflavin across the corneal stroma. The collagen fibers are arranged circumferentially in the corneal periphery,2,3 and any CXL preferentially involving this part of the cornea may lead to
Figure 1. Circumferential superficial contraction lines run from the inner part of the ICRS.
J CATARACT REFRACT SURG - VOL 38, OCTOBER 2012
1880
LETTERS
Figure 2. Bottom left: Curvature topography of the left eye after ICRS implantation but before the CXL procedure. Top left: Curvature topography of the left eye 1 year after the CXL procedure. Right: Difference map showing marked central corneal steepening in the area inside the ring segments.
central steepening. In our case, these limbal fibers were isolated somewhat from the central cornea by the ICRS. Although this is an unusual case, it illustrates that asymmetric corneal contraction could lead to unwanted focal corneal effects. Juan Carlos Abad, MD Medellin, Colombia REFERENCES 1. Kılıc‚ A, Kamburoglu G, Akıncı A. Riboflavin injection into the corneal channel for combined collagen crosslinking and intrastromal corneal ring segment implantation. J Cataract Refract Surg 2012; 38:878–883 2. Meek KM, Newton RH. Organization of collagen fibrils in the corneal stroma in relation to mechanical properties and surgical practice. J Refract Surg 1999; 15:695–699 3. Meek KM, Boote C. The organization of collagen in the corneal stroma. Exp Eye Res 2004; 78:503–512
OTHER CITED MATERIAL A. Spoerl E, personal communication, August 2, 2010
Multifocal IOLs as a low vision aid in eyes with AMD In their study of a magnification strategy for multifocal intraocular lens (IOL) implantation in
cataractous eyes with age-related macular degeneration (AMD),1 Gayton et al. used a refractive target of 2.00 diopters (D) and report improvement of uncorrected near visual acuity (UNVA) in 90% of eyes and of corrected distance visual acuity (CDVA) in 70% of eyes. Although the use of diffractive multifocal IOLs in eyes with even early signs of maculopathy is questionable, the introduction of these IOLs as a low vision aid (LVA) in advanced AMD opens a new chapter of potential applications. We would like to add to the existing experience our results using a multifocal IOL (Restor C4.0 D near add) as an LVA in eyes with AMD conducted at our institute (Ophthalmos Research and Therapeutic Institute) and at the Leipzig University Eye Clinic.A Twenty-nine eyes (24 patients) with dry AMD were divided into 3 groups based on the severity of maculopathy (quantified by fluorescein angiography). The first group (n Z 9 eyes) had early cataract, mild AMD, and a preoperative CDVA better than 20/40. The refractive target was emmetropia. Postoperatively, 66% of eyes achieved a UNVA of Jaeger (J)3 or better but no improvement compared with the preoperative CNVA. The second group (n Z 15 eyes) had a preoperative CDVA between 20/40 and 20/400, early cataract, and moderate to advanced
J CATARACT REFRACT SURG - VOL 38, OCTOBER 2012
endothelial damage, as improved visual acuity may occur with decreased endothelial cell count in CXL.6 Further studies are needed to evaluate the safety of this procedure. Zhen-Yong Zhang, MD Xing-Ru Zhang, MS Shanghai, China REFERENCES 1. Kılıc‚ A, Kamburoglu G, Akıncı A. Riboflavin injection into the corneal 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 J Ophthalmol 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 riboflavin and postoperative pain in corneal collagen crosslinking; excimer 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 corneas 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 crosslinking with riboflavin and ultraviolet-A irradiation in patients with thin corneas. Am J Ophthalmol 2012; 153:24–28
Paradoxical central corneal steepening after collagen crosslinking in a case with intrastromal corneal ring segments We read with interest the article by Kilic¸ et al.1 about enhancing epithelium-off corneal collagen crosslinking (CXL) by injecting riboflavin into the intrastromal corneal ring segment (ICRS) channels when performing the 2 procedures simultaneously. We would like to share one unusual experience that might relate to this type of practice. A 16-year-old man with a strong family history of keratoconus presented to our hospital with nonorthogonal with-the-rule astigmatism compatible with early keratoconus in both eyes. The preoperative data were uncorrected distance visual acuity (UDVA) of 20/50 in both eyes, and the refraction 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 similar procedure in November of the same year in the right eye. The UDVA improved to 20/25 in both eyes, and the refraction became C0.25 1.00 15 Z 20/20 in the right eye and C1.00 2.00 153 Z 20/20 in the
1879
left eye. In March 2009, epithelium-off bilateral CXL with 0.1% riboflavin and 20% dextran was performed using a 3 mW/cm2 ultraviolet-A (UVA) device (Costruzione Strumenti Oftalmici) and a 8.0 mm spot for 30 minutes. Two days later, the patient presented with loss of vision in the left eye. A white superficial haze that extended from the internal border of the nasal to the temporal ICRS was found. The epithelium closed uneventfully in both eyes, but no refractions could be obtained in the left eye during the first month. After 1 month, the UDVA was 20/25 in the right eye and 20/80 in the left eyere and the corrected distance visual acuity was C0.25 2.50 14 Z 20/20 and 3.50 2.25 165 Z 20/40, respectively. A circumferential haze was noted in the left eye; it had contraction marks that radiated from the ring segments (Figure 1) forming the equivalent of a dome of a cathedral (Figure 2, 1-year topography differential map), paradoxically increasing the central corneal curvature. The haze gradually decreased, and 2 years after the surgery the UDVA was 20/20 in the right eye and 20/40 in the left eye and the refraction was C0.75 2.50 Z 20/20 and 1.00 6.00 17 Z 20/30, respectively, with 1C haze in the left eye. The reason for this paradoxical response in the left eye of a bilateral case remains unclear, but one hypothesis is that the additional riboflavin that went into the ICRS channels enhanced the UVA-induced CXL to such an extent that it acted as a contraction ring steepening the central part of the cornea.A We are currently suturing the ring channels when performing simultaneous ICRS implantation and CXL to prevent the uneven distribution of riboflavin across the corneal stroma. The collagen fibers are arranged circumferentially in the corneal periphery,2,3 and any CXL preferentially involving this part of the cornea may lead to
Figure 1. Circumferential superficial contraction lines run from the inner part of the ICRS.
J CATARACT REFRACT SURG - VOL 38, OCTOBER 2012
1880
LETTERS
Figure 2. Bottom left: Curvature topography of the left eye after ICRS implantation but before the CXL procedure. Top left: Curvature topography of the left eye 1 year after the CXL procedure. Right: Difference map showing marked central corneal steepening in the area inside the ring segments.
central steepening. In our case, these limbal fibers were isolated somewhat from the central cornea by the ICRS. Although this is an unusual case, it illustrates that asymmetric corneal contraction could lead to unwanted focal corneal effects. Juan Carlos Abad, MD Medellin, Colombia REFERENCES 1. Kılıc‚ A, Kamburoglu G, Akıncı A. Riboflavin injection into the corneal channel for combined collagen crosslinking and intrastromal corneal ring segment implantation. J Cataract Refract Surg 2012; 38:878–883 2. Meek KM, Newton RH. Organization of collagen fibrils in the corneal stroma in relation to mechanical properties and surgical practice. J Refract Surg 1999; 15:695–699 3. Meek KM, Boote C. The organization of collagen in the corneal stroma. Exp Eye Res 2004; 78:503–512
OTHER CITED MATERIAL A. Spoerl E, personal communication, August 2, 2010
Multifocal IOLs as a low vision aid in eyes with AMD In their study of a magnification strategy for multifocal intraocular lens (IOL) implantation in
cataractous eyes with age-related macular degeneration (AMD),1 Gayton et al. used a refractive target of 2.00 diopters (D) and report improvement of uncorrected near visual acuity (UNVA) in 90% of eyes and of corrected distance visual acuity (CDVA) in 70% of eyes. Although the use of diffractive multifocal IOLs in eyes with even early signs of maculopathy is questionable, the introduction of these IOLs as a low vision aid (LVA) in advanced AMD opens a new chapter of potential applications. We would like to add to the existing experience our results using a multifocal IOL (Restor C4.0 D near add) as an LVA in eyes with AMD conducted at our institute (Ophthalmos Research and Therapeutic Institute) and at the Leipzig University Eye Clinic.A Twenty-nine eyes (24 patients) with dry AMD were divided into 3 groups based on the severity of maculopathy (quantified by fluorescein angiography). The first group (n Z 9 eyes) had early cataract, mild AMD, and a preoperative CDVA better than 20/40. The refractive target was emmetropia. Postoperatively, 66% of eyes achieved a UNVA of Jaeger (J)3 or better but no improvement compared with the preoperative CNVA. The second group (n Z 15 eyes) had a preoperative CDVA between 20/40 and 20/400, early cataract, and moderate to advanced
J CATARACT REFRACT SURG - VOL 38, OCTOBER 2012