CONSULTATION SECTION
Refractive Surgical Problem Edited by Marcony R. Santhiago, MD, PhD
A 47-year-old woman was referred for a second opinion after a laser in situ keratomileusis (LASIK) enhancement for hyperopic regression. The patient presented with decreased visual acuity in the left eye after an enhancement. The patient had uneventful hyperopic LASIK with a mechanical microkeratome in 2003 to correct +4.50 diopters (D) in the right eye and +4.00 D in the left eye. In 2013, the patient presented to the surgeon who performed the original surgery with decreased uncorrected distance visual acuity (UDVA) and a refraction of +3.00 0.50 165 in the right eye and +2.50 0.50 170 in the left eye, showing hyperopic regression (Figure 1). Spectacle dependence was her chief complaint. The corrected visual acuity for near and distance was 20/20 in both eyes. The surgeon was not able to identify the margins of the original flap in either eye and decided to perform an enhancement, creating a new femtosecond LASIK flap (100 mm) that was theoretically thinner than the original; the diameter of the new flap was 8.5 mm. The enhancement in the right eye was uneventful. In the left eye, the surgeon found the new margin with a
Sinskey hook and approached the new flap with a blunt spatula. However, a thin sliver of tissue representing the posterior layer of the old flap was loose, creating folds between the new, thinner flap and the residual stroma. The thin posterior part of the old flap tore apart as the surgeon tried to reposition the flap after the ablation. The stroma in the left eye was therefore irregular, missing slivers of tissue. Using this approach, the surgeon had to have been aware there would be 3 virtual layers as follows: (1) the new thin flap; (2) the posterior part of the old flap; (3) the residual stroma. One month after the enhancement, the refraction was plano 0.25 65 in the right eye and 1.50 1.25 125 in the left eye. The corrected distance visual acuity (CDVA) at that time was 20/20 in the right eye and 20/40 1 in the left eye. The patient had significant complaints about her quality of vision, especially under dim light conditions. When the patient was referred approximately 6 months after the enhancement, the Scheimpflug tomographic maps showed a steep central cornea in the left eye. Examination of the maps 1 month after surgery showed that the central cornea had flattened and the
Figure 1. Scheimpflug tomographic map of left eye before enhancement.
1048
Q 2014 ASCRS and ESCRS Published by Elsevier Inc.
0886-3350/$ - see front matter http://dx.doi.org/10.1016/j.jcrs.2014.04.003
CONSULTATION SECTION
1049
Figure 2. Scheimpflug tomographic map of left eye 1 month after enhancement.
epithelium had apparently filled the areas with loss of stroma (Figures 2 and 3). In light of the possible complications of cutting a new flap in the presence of an old interface, how would you
have first approached this patient if a flap relift were not possible or in light of the potentially higher incidence of epithelial ingrowth after relifting an old flap created with a mechanical microkeratome? Would you have
Figure 3. Scheimpflug tomographic map of left eye approximately 6 moths after enhancement.
J CATARACT REFRACT SURG - VOL 40, JUNE 2014
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CONSULTATION SECTION
considered surface ablation even with its higher chances of regression? What would have been your approach if the original regression were myopic? How about refractive lens exchange (RLE)? After the unsuccessful enhancement in the left eye and considering that the curvature maps do not necessarily match the stromal curvature, how would you approach this case?
conservative approach and would give time for the cornea to remodel completely while improving visual function. Sonia H. Yoo, MD Miami, Florida, USA Dr. Yoo is a consultant to Alcon, Abbott Medical Optics, and Carl Zeiss Meditec. REFERENCES
- It has been reported that approximately 5% to 28% of patients who have LASIK require enhancements.1 Factors associated with retreatment include age greater than 40 years, high initial refractive errors, high astigmatism, and primary LASIK for hyperopia. So, it is not surprising that this patient ultimately required an enhancement. Strategies for retreatments include surface ablation, cutting a new flap, and flap relifting. Although surface ablation can be associated with postoperative haze and regression and flap relifting with epithelial ingrowth, these problems can be minimized by the application of intraoperative mitomycin-C (MMC) and use of a femtosecond laser to create a new side cut to the level of the old LASIK interface.2 Even in the case of epithelial ingrowth after LASIK retreatment, the visual acuity outcomes are generally good for patients who require flap lifting and scraping of the epithelial cells in the interface.3 My choice for retreatment of this patient would have been surface ablation with MMC or a new femtosecond laser–assisted side cut and flap lifting. I would prefer not to perform RLE in a 47 year old who still has some accommodative amplitude and who would not be an ideal multifocal intraocular lens (IOL) candidate given the previous hyperopic LASIK. This case highlights the difficulties that can arise from cutting a new flap for LASIK enhancement. Loss of slivers of tissue in the stroma can cause irregular astigmatism and loss of CDVA. At present, epithelial remodeling is helping fill in the areas of stromal tissue loss, and waiting another 6 to 12 months may lead to improved CDVA. Topography-guided surface ablation, not available in the United States, might be an option to improve the irregular astigmatism. If the stromal bed were thick enough, another therapeutic option might be to amputate the flap and then perform phototherapeutic keratectomy with MMC. It is likely, however, that the patient would require another refractive correction once the irregular astigmatism improved. Finally, use of a rigid gaspermeable (RGP) contact lens would be a more
1. Hersh PS, Fry KL, Bishop DS. Incidence and associations of retreatment after LASIK. Ophthalmology 2003; 110:748–754 2. Vaddavalli PK, Yoo SH, Diakonis VF, Canto AP, Shah NV, Haddock LJ, Feuer WJ, Culbertson WW. Femtosecond laser–assisted retreatment for residual refractive errors after laser in situ keratomileusis. J Cataract Refractive Surg 2013; 39:1241–1247 3. Henry CR, Canto AP, Galor A, Vaddavalli PK, Culbertson WW, Yoo SH. Epithelial ingrowth after LASIK: clinical characteristics, risk factors, and visual outcomes in patient requiring flap lift. J Refract Surg 2012; 28:488–492
- Surgical management of residual errors by excimer laser photoablation (enhancement) can be performed by lifting the flap, by cutting a new flap, or by surface ablation. I have successfully lifted flaps 10 years after primary LASIK. Potential problems associated with lifting flaps include the increased risks for epithelial ingrowth and diffuse lamellar keratitis. It is also possible that subepithelial fibrosis, flap tears, and striae occur at a higher rate with lifting than with recutting. The key issue is that most complications that can occur with flap lifting are generally reversible, self-limited, or treatable. Another reason lifting may be preferred over recutting is the possibility of future enhancements. I would not recommend cutting a new flap, and an 8.5 mm flap diameter is not large enough for hyperopic eyes. Although the method of relifting the old flap and treating the residual refractive errors appears to be safer than flap recutting and is the standard of care for retreatment, it has a much higher incidence of epithelial ingrowth than primary LASIK, with reported rates varying from 1.7% to 12.7%. Even with retreatments, the incidence seems to be lower in eyes with flaps created with a femtosecond laser (1.8%) than in eyes with flaps created with a microkeratome (12.7%).1 This is believed to be due to the vertical configuration of the side cut created by a femtosecond laser. Tran et al.2 propose a new method of LASIK retreatment in which a new side cut is created with a femtosecond laser, with the new cut reaching up to the old interface. Creating a new side cut in the old flap margin to facilitate flap lifting potentially reduces the incidence of epithelial ingrowth.3
J CATARACT REFRACT SURG - VOL 40, JUNE 2014
Refractive Surgical Problem Edited by Marcony R. Santhiago, MD, PhD
A 47-year-old woman was referred for a second opinion after a laser in situ keratomileusis (LASIK) enhancement for hyperopic regression. The patient presented with decreased visual acuity in the left eye after an enhancement. The patient had uneventful hyperopic LASIK with a mechanical microkeratome in 2003 to correct +4.50 diopters (D) in the right eye and +4.00 D in the left eye. In 2013, the patient presented to the surgeon who performed the original surgery with decreased uncorrected distance visual acuity (UDVA) and a refraction of +3.00 0.50 165 in the right eye and +2.50 0.50 170 in the left eye, showing hyperopic regression (Figure 1). Spectacle dependence was her chief complaint. The corrected visual acuity for near and distance was 20/20 in both eyes. The surgeon was not able to identify the margins of the original flap in either eye and decided to perform an enhancement, creating a new femtosecond LASIK flap (100 mm) that was theoretically thinner than the original; the diameter of the new flap was 8.5 mm. The enhancement in the right eye was uneventful. In the left eye, the surgeon found the new margin with a
Sinskey hook and approached the new flap with a blunt spatula. However, a thin sliver of tissue representing the posterior layer of the old flap was loose, creating folds between the new, thinner flap and the residual stroma. The thin posterior part of the old flap tore apart as the surgeon tried to reposition the flap after the ablation. The stroma in the left eye was therefore irregular, missing slivers of tissue. Using this approach, the surgeon had to have been aware there would be 3 virtual layers as follows: (1) the new thin flap; (2) the posterior part of the old flap; (3) the residual stroma. One month after the enhancement, the refraction was plano 0.25 65 in the right eye and 1.50 1.25 125 in the left eye. The corrected distance visual acuity (CDVA) at that time was 20/20 in the right eye and 20/40 1 in the left eye. The patient had significant complaints about her quality of vision, especially under dim light conditions. When the patient was referred approximately 6 months after the enhancement, the Scheimpflug tomographic maps showed a steep central cornea in the left eye. Examination of the maps 1 month after surgery showed that the central cornea had flattened and the
Figure 1. Scheimpflug tomographic map of left eye before enhancement.
1048
Q 2014 ASCRS and ESCRS Published by Elsevier Inc.
0886-3350/$ - see front matter http://dx.doi.org/10.1016/j.jcrs.2014.04.003
CONSULTATION SECTION
1049
Figure 2. Scheimpflug tomographic map of left eye 1 month after enhancement.
epithelium had apparently filled the areas with loss of stroma (Figures 2 and 3). In light of the possible complications of cutting a new flap in the presence of an old interface, how would you
have first approached this patient if a flap relift were not possible or in light of the potentially higher incidence of epithelial ingrowth after relifting an old flap created with a mechanical microkeratome? Would you have
Figure 3. Scheimpflug tomographic map of left eye approximately 6 moths after enhancement.
J CATARACT REFRACT SURG - VOL 40, JUNE 2014
1050
CONSULTATION SECTION
considered surface ablation even with its higher chances of regression? What would have been your approach if the original regression were myopic? How about refractive lens exchange (RLE)? After the unsuccessful enhancement in the left eye and considering that the curvature maps do not necessarily match the stromal curvature, how would you approach this case?
conservative approach and would give time for the cornea to remodel completely while improving visual function. Sonia H. Yoo, MD Miami, Florida, USA Dr. Yoo is a consultant to Alcon, Abbott Medical Optics, and Carl Zeiss Meditec. REFERENCES
- It has been reported that approximately 5% to 28% of patients who have LASIK require enhancements.1 Factors associated with retreatment include age greater than 40 years, high initial refractive errors, high astigmatism, and primary LASIK for hyperopia. So, it is not surprising that this patient ultimately required an enhancement. Strategies for retreatments include surface ablation, cutting a new flap, and flap relifting. Although surface ablation can be associated with postoperative haze and regression and flap relifting with epithelial ingrowth, these problems can be minimized by the application of intraoperative mitomycin-C (MMC) and use of a femtosecond laser to create a new side cut to the level of the old LASIK interface.2 Even in the case of epithelial ingrowth after LASIK retreatment, the visual acuity outcomes are generally good for patients who require flap lifting and scraping of the epithelial cells in the interface.3 My choice for retreatment of this patient would have been surface ablation with MMC or a new femtosecond laser–assisted side cut and flap lifting. I would prefer not to perform RLE in a 47 year old who still has some accommodative amplitude and who would not be an ideal multifocal intraocular lens (IOL) candidate given the previous hyperopic LASIK. This case highlights the difficulties that can arise from cutting a new flap for LASIK enhancement. Loss of slivers of tissue in the stroma can cause irregular astigmatism and loss of CDVA. At present, epithelial remodeling is helping fill in the areas of stromal tissue loss, and waiting another 6 to 12 months may lead to improved CDVA. Topography-guided surface ablation, not available in the United States, might be an option to improve the irregular astigmatism. If the stromal bed were thick enough, another therapeutic option might be to amputate the flap and then perform phototherapeutic keratectomy with MMC. It is likely, however, that the patient would require another refractive correction once the irregular astigmatism improved. Finally, use of a rigid gaspermeable (RGP) contact lens would be a more
1. Hersh PS, Fry KL, Bishop DS. Incidence and associations of retreatment after LASIK. Ophthalmology 2003; 110:748–754 2. Vaddavalli PK, Yoo SH, Diakonis VF, Canto AP, Shah NV, Haddock LJ, Feuer WJ, Culbertson WW. Femtosecond laser–assisted retreatment for residual refractive errors after laser in situ keratomileusis. J Cataract Refractive Surg 2013; 39:1241–1247 3. Henry CR, Canto AP, Galor A, Vaddavalli PK, Culbertson WW, Yoo SH. Epithelial ingrowth after LASIK: clinical characteristics, risk factors, and visual outcomes in patient requiring flap lift. J Refract Surg 2012; 28:488–492
- Surgical management of residual errors by excimer laser photoablation (enhancement) can be performed by lifting the flap, by cutting a new flap, or by surface ablation. I have successfully lifted flaps 10 years after primary LASIK. Potential problems associated with lifting flaps include the increased risks for epithelial ingrowth and diffuse lamellar keratitis. It is also possible that subepithelial fibrosis, flap tears, and striae occur at a higher rate with lifting than with recutting. The key issue is that most complications that can occur with flap lifting are generally reversible, self-limited, or treatable. Another reason lifting may be preferred over recutting is the possibility of future enhancements. I would not recommend cutting a new flap, and an 8.5 mm flap diameter is not large enough for hyperopic eyes. Although the method of relifting the old flap and treating the residual refractive errors appears to be safer than flap recutting and is the standard of care for retreatment, it has a much higher incidence of epithelial ingrowth than primary LASIK, with reported rates varying from 1.7% to 12.7%. Even with retreatments, the incidence seems to be lower in eyes with flaps created with a femtosecond laser (1.8%) than in eyes with flaps created with a microkeratome (12.7%).1 This is believed to be due to the vertical configuration of the side cut created by a femtosecond laser. Tran et al.2 propose a new method of LASIK retreatment in which a new side cut is created with a femtosecond laser, with the new cut reaching up to the old interface. Creating a new side cut in the old flap margin to facilitate flap lifting potentially reduces the incidence of epithelial ingrowth.3
J CATARACT REFRACT SURG - VOL 40, JUNE 2014
