1936
CONSULTATION SECTION
stop the progression of the post-LASIK ectasia but will also often result in improved corneal shape and improved uncorrected distance visual acuity (UDVA) and CDVA (with spectacles). I would advise the patient to seek treatment with CXL at a local center in the very near future because post-LASIK ectasia is progressive in most cases and the patient has already lost CDVA. If the patient opted to seek treatment with me, I would enroll her in our ongoing epi-on CXL clinical trial. Although some peer-reviewed articles suggest that epi-on CXL is not effective, those studies had major flaws in their technique for riboflavin loading of the cornea, specifically failure to confirm by slitlamp observation that sufficient riboflavin was present in the cornea before proceeding to the UV-light treatment. After CXL, the patient would be expected to have mild improvement in corneal shape over the first 1 to 2 years and typically would have a 1- to 2-line improvement in UDVA and CDVA. In the years to come, the patient could opt for a variety of technologies to further improve her vision. Although the patient was reported to be contact lens intolerant, we have found that many patients with so-called contact lens intolerant keratoconus or postLASIK ectasia become comfortable and achieve excellent vision with scleral contact lenses. In addition to scleral lenses, the typical improvement in corneal shape can allow the patient to consider corneal reshaping procedures, such as topography-guided PRK. Of note: As the corneal shape improves after epi-on CXL, the amount of reshaping of the cornea is often less if performed 1 to 2 years postoperatively than if topography-guided PRK is performed as an initial procedure. In summary, intraoperative pachymetry is an important step to identify cases in which deeper-thanexpected flaps were created during LASIK. In addition, epi-on CXL performed soon after the diagnosis of post-LASIK ectasia can help minimize the severity of the condition and allow the patient to become eligible for future corneal-reshaping procedures. William Trattler, MD Miami, Florida, USA REFERENCES 1. Reinstein DZ, Srivannaboon S, Archer TJ, Silverman RH, Sutton H, Coleman DJ. Probability model of the inaccuracy of residual stromal thickness prediction to reduce the risk of ectasia after LASIK. Part II: quantifying population risk. J Refract Surg 2006; 22:861–870 2. Reinstein DZ, Srivannaboon S, Archer TJ, Silverman RH, Sutton H, Coleman DJ. Probability model of the inaccuracy of residual stromal thickness prediction to reduce the risk of ectasia after LASIK. Part I: quantifying individual risk. J Refract Surg 2006; 22:851–860
- Ectasia is the most feared complication after excimer laser surgery and is even more disconcerting when it happens after uneventful surgery in an apparently good candidate, as in this case. There was not enough information in the preoperative evaluation about the corneal tomography and aberrometry; it is crucial to analyze these data before any corneal refractive surgery is performed. The best way to approach this case would be to remodel the irregular shape of the cornea with ICRS implantation and 3 months later, after adequate corneal healing, perform corneal CXL to stabilize the progressive ectasia. Even though refractive stability after ICRS implantation has been reported in postLASIK ectasia,1,2 in this case the increased refractive error with a high astigmatic defect suggests the need for additional treatment with corneal CXL. I would not recommend PRK because of the anterior weakness of the cornea caused by the thick flap cut and the thin pachymetry shown on OCT. In addition, CXL will not be safe in a thinner cornea. I have seen progression of ectasia in post-LASIK eyes despite ICRS implantation. That is why I would suggest early CXL after diagnosing the ectasia. Some studies of CXL in secondary ectasia, such as the one by Poli et al.,3 report good corneal stabilization and safety. When post-LASIK ectasia is suspected, a close follow-up (every 4 to 6 months) should be performed with clinical and tomography examinations. If corneal steepening is seen on the topographic and tomographic maps and a decrease in the visual acuity is found, early corneal CXL should be performed. Traditionally, I have used rules to protect the eyes from ectasia after LASIK. They are to leave more than 250 mm in the RSB or to leave, after the ablation, more than one half CCT for the RSB. Pallikaris et al.4 published a retrospective study that found no post-LASIK ectasia in patients with an RSB greater than 325 mm and with refractive corrections less than 8.0 D. Nowadays, everybody is willing to leave the greatest RSB, preferably more than 300 mm. In this case, the risk factors for corneal ectasia could have been a thick corneal flap, a deep-volume ablation per diopter, and a relative low RSB. Claudia Blanco, MD Cali, Colombia REFERENCES 1. Kymionis GD, Tsiklis NS, Pallikaris AI, Kounis G, Diakonis VF, Astyrakakis N, Siganos CS. Long-term follow-up of Intacs for post-LASIK corneal ectasia. Ophthalmology 2006; 113:1909– 1917 JL, Vega-Estrada A, Baviera J, Beltra n J, Cobo2. Brenner LF, Alio Soriano R. Indications for intrastromal corneal ring segments in
J CATARACT REFRACT SURG - VOL 39, DECEMBER 2013
CONSULTATION SECTION
ectasia after laser in situ keratomileusis. J Cataract Refract Surg 2012; 38:2117–2124 3. Poli M, Cornut P-L, Balmitgere T, Aptel F, Janin H, Burillon C. Prospective study of corneal collagen cross-linking efficacy and tolerance in the treatment of keratoconus and corneal ectasia: 3-year results. Cornea 2013; 32:583–590 4. Pallikaris IG, Kymionis GD, Astyrakakis NI. Corneal ectasia induced by laser in situ keratomileusis. J Cataract Refract Surg 2001; 27:1796–1802
- The data support the history that this patient was at low risk for ectasia, considering the preoperative parameters for the LASIK procedure. My approach to this case would be corneal CXL because I believe the progression of the ectasia may continue in the future. Unfortunately, in my experience, post-LASIK ectasia does not observe the usual “rules” of keratoconus, which usually include stabilization after the age of 40 years. We have studied thoroughly several markers that may help document progressive ectasia and have reported that surprisingly, the markers are the index of surface variance (ISV) and the index of height decentration (IHD), both of which are asymmetry indices provided by Pentacam imaging (Oculus). The ISV and IHD appear far more sensitive in monitoring corneal ectasia than traditionally evaluated acuity, average keratometry, and corneal thickness.1 I would not suggest observing this case because I believe there is significant ectasia already. I would consult the patient to determine whether there is any eye rubbing, and considering the significant corneal and refractive irregularity and the reduced CDVA, I would offer this patient not only CXL but high-fluence corneal CXL combined with “frugal” topography-guided PRK normalization of the irregularity to CDVA (with spectacles). We introduced a topography-guided platform2 to use in a therapeutic manner in these cases. We have since reported that this approach, the Athens protocol, provides excellent ectasia stabilization and relatively satisfactory results in visual rehabilitation.3–7 In our latest long-term assessment of keratoconus cases,8 we found that Scheimpflug-driven excimer laser normalization may be better than using a Placidodisk platform. This intervention may require several weeks to heal compared with simple CXL, and ectasia cases usually require additional refractive correction with spectacles and/or soft contact lenses posttreatment. The resulting refractive change is usually a myopic shift because the normalization of such inferior steepening will attempt to steepen the central cornea and flatten the inferior ectasia, normalizing the central cornea.
1937
If the residual refractive error could not be corrected after this procedure, I would wait at least 3 to 6 months to ascertain what that refraction would be, with spectacles or contact lenses as an option, as well as the possibility of phakic IOL implantation. In Europe, we can implant toric IOLs that may address this problem. Last, looking at this significant complication, one may argue whether prophylactic CXL treatment with very high fluence at the completion of the primary LASIK procedure would have prevented the ectasia. We have introduced9 and reported prophylactic CXL in LASIK with encouraging preliminary results in LASIK stability, which were confirmed by higher hyperopic LASIK stability over a long-term follow-up.10,11 A. John Kanellopoulos, MD Athens, Greece New York City, New York, USA Dr. Kanellopoulos has a financial interest in Alcon Laboratories, Inc. and Avedro. REFERENCES 1. Kanellopoulos AJ, Asimellis G. Revisiting keratoconus diagnosis and progression classification based on evaluation of corneal asymmetry indices, derived from Scheimpflug imaging in keratoconic and suspect cases. Clin Ophthalmol 2013; 7:1539–1548. Available at: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC 3735334/pdf/opth-7-1539.pdf. Accessed September 23, 2013 2. Kanellopoulos AJ, Binder PS. Collagen cross-linking (CCL) sequential topography-guided PRK; a temporizing alternative for keratoconus to penetrating keratoplasty. Cornea 2007; 26:891–895 3. Kanellopoulos AJ. Comparison of sequential vs same-day simultaneous collagen cross-linking and topography-guided PRK for treatment of keratoconus. J Refract Surg 2009; 25:S812–S818 4. Kanellopoulos AJ. Collagen cross-linking in early keratoconus with riboflavin in a femtosecond laser-created pocket: initial clinical results. J Refract Surg 2009; 25:1034–1037 5. Krueger RR, Kanellopoulos AJ. Stability of simultaneous topography-guided photorefractive keratectomy and riboflavin/ UVA cross-linking for progressive keratoconus: case reports. J Refract Surg 2010; 26:S827–S832 6. Kanellopoulos AJ, Binder PS. Management of corneal ectasia after LASIK with combined, same-day, topography-guided partial transepithelial PRK and collagen cross-linking: the Athens Protocol. J Refract Surg 2011; 27:323–331 7. Kanellopoulos AJ. Long term results of a prospective randomized bilateral eye comparison trial of higher fluence, shorter duration ultraviolet A radiation, and riboflavin collagen cross linking for progressive keratoconus. Clin Ophthalmol 2012; 6:97–101. Available at: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC 3261695/pdf/opth-6-097.pdf. Accessed September 12, 2013 8. Kanellopoulos AJ, Asimellis G. Comparison of Placido disc and Scheimpflug image-derived topography-guided excimer laser surface normalization combined with higher fluence CXL: the Athens Protocol, in progressive keratoconus. Clin Ophthalmol 2013; 7:1385–1396. Available at: http://www.ncbi.nlm.nih.gov/ pmc/articles/PMC3720663/pdf/opth-7-1385.pdf. Accessed September 23, 2013
J CATARACT REFRACT SURG - VOL 39, DECEMBER 2013
CONSULTATION SECTION
stop the progression of the post-LASIK ectasia but will also often result in improved corneal shape and improved uncorrected distance visual acuity (UDVA) and CDVA (with spectacles). I would advise the patient to seek treatment with CXL at a local center in the very near future because post-LASIK ectasia is progressive in most cases and the patient has already lost CDVA. If the patient opted to seek treatment with me, I would enroll her in our ongoing epi-on CXL clinical trial. Although some peer-reviewed articles suggest that epi-on CXL is not effective, those studies had major flaws in their technique for riboflavin loading of the cornea, specifically failure to confirm by slitlamp observation that sufficient riboflavin was present in the cornea before proceeding to the UV-light treatment. After CXL, the patient would be expected to have mild improvement in corneal shape over the first 1 to 2 years and typically would have a 1- to 2-line improvement in UDVA and CDVA. In the years to come, the patient could opt for a variety of technologies to further improve her vision. Although the patient was reported to be contact lens intolerant, we have found that many patients with so-called contact lens intolerant keratoconus or postLASIK ectasia become comfortable and achieve excellent vision with scleral contact lenses. In addition to scleral lenses, the typical improvement in corneal shape can allow the patient to consider corneal reshaping procedures, such as topography-guided PRK. Of note: As the corneal shape improves after epi-on CXL, the amount of reshaping of the cornea is often less if performed 1 to 2 years postoperatively than if topography-guided PRK is performed as an initial procedure. In summary, intraoperative pachymetry is an important step to identify cases in which deeper-thanexpected flaps were created during LASIK. In addition, epi-on CXL performed soon after the diagnosis of post-LASIK ectasia can help minimize the severity of the condition and allow the patient to become eligible for future corneal-reshaping procedures. William Trattler, MD Miami, Florida, USA REFERENCES 1. Reinstein DZ, Srivannaboon S, Archer TJ, Silverman RH, Sutton H, Coleman DJ. Probability model of the inaccuracy of residual stromal thickness prediction to reduce the risk of ectasia after LASIK. Part II: quantifying population risk. J Refract Surg 2006; 22:861–870 2. Reinstein DZ, Srivannaboon S, Archer TJ, Silverman RH, Sutton H, Coleman DJ. Probability model of the inaccuracy of residual stromal thickness prediction to reduce the risk of ectasia after LASIK. Part I: quantifying individual risk. J Refract Surg 2006; 22:851–860
- Ectasia is the most feared complication after excimer laser surgery and is even more disconcerting when it happens after uneventful surgery in an apparently good candidate, as in this case. There was not enough information in the preoperative evaluation about the corneal tomography and aberrometry; it is crucial to analyze these data before any corneal refractive surgery is performed. The best way to approach this case would be to remodel the irregular shape of the cornea with ICRS implantation and 3 months later, after adequate corneal healing, perform corneal CXL to stabilize the progressive ectasia. Even though refractive stability after ICRS implantation has been reported in postLASIK ectasia,1,2 in this case the increased refractive error with a high astigmatic defect suggests the need for additional treatment with corneal CXL. I would not recommend PRK because of the anterior weakness of the cornea caused by the thick flap cut and the thin pachymetry shown on OCT. In addition, CXL will not be safe in a thinner cornea. I have seen progression of ectasia in post-LASIK eyes despite ICRS implantation. That is why I would suggest early CXL after diagnosing the ectasia. Some studies of CXL in secondary ectasia, such as the one by Poli et al.,3 report good corneal stabilization and safety. When post-LASIK ectasia is suspected, a close follow-up (every 4 to 6 months) should be performed with clinical and tomography examinations. If corneal steepening is seen on the topographic and tomographic maps and a decrease in the visual acuity is found, early corneal CXL should be performed. Traditionally, I have used rules to protect the eyes from ectasia after LASIK. They are to leave more than 250 mm in the RSB or to leave, after the ablation, more than one half CCT for the RSB. Pallikaris et al.4 published a retrospective study that found no post-LASIK ectasia in patients with an RSB greater than 325 mm and with refractive corrections less than 8.0 D. Nowadays, everybody is willing to leave the greatest RSB, preferably more than 300 mm. In this case, the risk factors for corneal ectasia could have been a thick corneal flap, a deep-volume ablation per diopter, and a relative low RSB. Claudia Blanco, MD Cali, Colombia REFERENCES 1. Kymionis GD, Tsiklis NS, Pallikaris AI, Kounis G, Diakonis VF, Astyrakakis N, Siganos CS. Long-term follow-up of Intacs for post-LASIK corneal ectasia. Ophthalmology 2006; 113:1909– 1917 JL, Vega-Estrada A, Baviera J, Beltra n J, Cobo2. Brenner LF, Alio Soriano R. Indications for intrastromal corneal ring segments in
J CATARACT REFRACT SURG - VOL 39, DECEMBER 2013
CONSULTATION SECTION
ectasia after laser in situ keratomileusis. J Cataract Refract Surg 2012; 38:2117–2124 3. Poli M, Cornut P-L, Balmitgere T, Aptel F, Janin H, Burillon C. Prospective study of corneal collagen cross-linking efficacy and tolerance in the treatment of keratoconus and corneal ectasia: 3-year results. Cornea 2013; 32:583–590 4. Pallikaris IG, Kymionis GD, Astyrakakis NI. Corneal ectasia induced by laser in situ keratomileusis. J Cataract Refract Surg 2001; 27:1796–1802
- The data support the history that this patient was at low risk for ectasia, considering the preoperative parameters for the LASIK procedure. My approach to this case would be corneal CXL because I believe the progression of the ectasia may continue in the future. Unfortunately, in my experience, post-LASIK ectasia does not observe the usual “rules” of keratoconus, which usually include stabilization after the age of 40 years. We have studied thoroughly several markers that may help document progressive ectasia and have reported that surprisingly, the markers are the index of surface variance (ISV) and the index of height decentration (IHD), both of which are asymmetry indices provided by Pentacam imaging (Oculus). The ISV and IHD appear far more sensitive in monitoring corneal ectasia than traditionally evaluated acuity, average keratometry, and corneal thickness.1 I would not suggest observing this case because I believe there is significant ectasia already. I would consult the patient to determine whether there is any eye rubbing, and considering the significant corneal and refractive irregularity and the reduced CDVA, I would offer this patient not only CXL but high-fluence corneal CXL combined with “frugal” topography-guided PRK normalization of the irregularity to CDVA (with spectacles). We introduced a topography-guided platform2 to use in a therapeutic manner in these cases. We have since reported that this approach, the Athens protocol, provides excellent ectasia stabilization and relatively satisfactory results in visual rehabilitation.3–7 In our latest long-term assessment of keratoconus cases,8 we found that Scheimpflug-driven excimer laser normalization may be better than using a Placidodisk platform. This intervention may require several weeks to heal compared with simple CXL, and ectasia cases usually require additional refractive correction with spectacles and/or soft contact lenses posttreatment. The resulting refractive change is usually a myopic shift because the normalization of such inferior steepening will attempt to steepen the central cornea and flatten the inferior ectasia, normalizing the central cornea.
1937
If the residual refractive error could not be corrected after this procedure, I would wait at least 3 to 6 months to ascertain what that refraction would be, with spectacles or contact lenses as an option, as well as the possibility of phakic IOL implantation. In Europe, we can implant toric IOLs that may address this problem. Last, looking at this significant complication, one may argue whether prophylactic CXL treatment with very high fluence at the completion of the primary LASIK procedure would have prevented the ectasia. We have introduced9 and reported prophylactic CXL in LASIK with encouraging preliminary results in LASIK stability, which were confirmed by higher hyperopic LASIK stability over a long-term follow-up.10,11 A. John Kanellopoulos, MD Athens, Greece New York City, New York, USA Dr. Kanellopoulos has a financial interest in Alcon Laboratories, Inc. and Avedro. REFERENCES 1. Kanellopoulos AJ, Asimellis G. Revisiting keratoconus diagnosis and progression classification based on evaluation of corneal asymmetry indices, derived from Scheimpflug imaging in keratoconic and suspect cases. Clin Ophthalmol 2013; 7:1539–1548. Available at: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC 3735334/pdf/opth-7-1539.pdf. Accessed September 23, 2013 2. Kanellopoulos AJ, Binder PS. Collagen cross-linking (CCL) sequential topography-guided PRK; a temporizing alternative for keratoconus to penetrating keratoplasty. Cornea 2007; 26:891–895 3. Kanellopoulos AJ. Comparison of sequential vs same-day simultaneous collagen cross-linking and topography-guided PRK for treatment of keratoconus. J Refract Surg 2009; 25:S812–S818 4. Kanellopoulos AJ. Collagen cross-linking in early keratoconus with riboflavin in a femtosecond laser-created pocket: initial clinical results. J Refract Surg 2009; 25:1034–1037 5. Krueger RR, Kanellopoulos AJ. Stability of simultaneous topography-guided photorefractive keratectomy and riboflavin/ UVA cross-linking for progressive keratoconus: case reports. J Refract Surg 2010; 26:S827–S832 6. Kanellopoulos AJ, Binder PS. Management of corneal ectasia after LASIK with combined, same-day, topography-guided partial transepithelial PRK and collagen cross-linking: the Athens Protocol. J Refract Surg 2011; 27:323–331 7. Kanellopoulos AJ. Long term results of a prospective randomized bilateral eye comparison trial of higher fluence, shorter duration ultraviolet A radiation, and riboflavin collagen cross linking for progressive keratoconus. Clin Ophthalmol 2012; 6:97–101. Available at: http://www.ncbi.nlm.nih.gov/pmc/articles/PMC 3261695/pdf/opth-6-097.pdf. Accessed September 12, 2013 8. Kanellopoulos AJ, Asimellis G. Comparison of Placido disc and Scheimpflug image-derived topography-guided excimer laser surface normalization combined with higher fluence CXL: the Athens Protocol, in progressive keratoconus. Clin Ophthalmol 2013; 7:1385–1396. Available at: http://www.ncbi.nlm.nih.gov/ pmc/articles/PMC3720663/pdf/opth-7-1385.pdf. Accessed September 23, 2013
J CATARACT REFRACT SURG - VOL 39, DECEMBER 2013
