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Consultation section: refractive surgical problem
CONSULTATION SECTION
sion. Therefore, the final refractive error is higher than preoperatively. Topical steroids may be effective in treating superficial and interface haze. However, this patient was also treated with low-dose steroids for 8 weeks, and there was no resolution of the scars. One approach is to try to eliminate the corneal scar and the refractive error with PTK. I do not recommend this treatment in this case because photoablating the anterior third of the corneal stroma induces an aggressive corneal wound-healing response and excessive haze. If there were no contraindications (eg, collagen tissue disease or systemic vascular disease), I would manage this patient by excimer-laser-assisted ALK. After the corneal scar tissue is removed, the residual refractive error correction could be treated in another step. KAMIL BILGIHAN, MD Ankara, Turkey
f The history suggests that DLK occurred in the early postoperative period and resulted in scarring. Diffuse lamellar keratitis frequently occurs in eyes with epithelial defects. Perhaps the DLK was not diagnosed or treated aggressively enough for fear of delayed epithelial healing. As scars caused by DLK resolve slowly (2 or more years), 1 option would be to wait and place the patient on steroids (eg, fluorometholone) for a couple of months. I would also discuss the surgical option of penetrating corneal graft, especially in the right eye as it has corneal thinning and a posterior keratoconus. MICHAEL C. KNORZ, MD Mannheim, Germany
f This case probably corresponds to a severe end-stage case of grade IV DLK. This complication is more frequent after mechanical corneal deepithelialization during surgery. In this case, it was unsuccessfully treated with steroids, which left a corneal scar that extends throughout the resected flap. The topographic images of both eyes show irregular astigmatism induced by the corneal scar and by a decentered ablation. I would first try a trial of inverted aspheric gaspermeable contact lens wear. I would use maximal asphericity (around 10 to 12 points), a base curve of 39.50, and a large diameter (around 10.0 mm). This avoids lens decentration and improves stability in cases
with decentered ablations from previous laser treatments. Contact lenses with smaller diameters tend to decenter and produce halos, star bursts, and even monocular diplopia. On the other hand, diameters larger than 10.2 mm are not recommended because they would compromise lachrymal exchange. If the patient is intolerant of these new contact lenses, surgical options can be considered. One is to perform homoplastic keratomileusis using a 160 m plate in the right eye and a 200 m plate in the left eye. I recommend using a donor flap with a 0.5 m smaller diameter to avoid interface epithelialization. The flap should be sutured with an 8-pass antitorque suture that is removed 1 week postoperatively. After a minimum of 6 months, refraction should be taken and the refractive error surgically treated. A topography-assisted flyingspot laser could be used to perform LASIK in which a new flap is made under the previous one. The ablation should be based on elevation topography so one can visualize the difference in height of the central and temporal cornea. The ablation should be 6.5 mm and central, with protection to the temporal side until the cornea is level. Then, the procedure should continue until the ablation is complete. To avoid a free flap, the previous flap should not be lifted. I would recommend soft contact lens use for the first day postoperatively. A second option is to perform central 6.5 mm PTK with temporal side protection using topography-assisted flying-spot ablation until the cornea is level and then continuing with a 6.5 mm ablation until the haze disappears. The refractive result will determine whether a lamellar refractive graft should be done. Before this procedure, a corneal epithelial basement membrane defect should be ruled out. Such a defect takes several weeks to heal, and the first epithelial defect took almost 2 weeks to resolve. SALOMON ESQUENAZI, MD Bogota´, Colombia
f Unfortunately, the preoperative pachymetry is not known. The Orbscan images show a posterior corneal bulge in both eyes, more evident in right. Moreover, the anterior topographies and elevation maps show prolate corneas, not oblate such as after LASIK for myopia. The clinical and topographical images suggest an iatrogenic keratectasia in both eyes. Therefore, if the patient has difficulty tolerating RGP lenses and has se-
J CATARACT REFRACT SURG—VOL 27, JANUARY 2001
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sion. Therefore, the final refractive error is higher than preoperatively. Topical steroids may be effective in treating superficial and interface haze. However, this patient was also treated with low-dose steroids for 8 weeks, and there was no resolution of the scars. One approach is to try to eliminate the corneal scar and the refractive error with PTK. I do not recommend this treatment in this case because photoablating the anterior third of the corneal stroma induces an aggressive corneal wound-healing response and excessive haze. If there were no contraindications (eg, collagen tissue disease or systemic vascular disease), I would manage this patient by excimer-laser-assisted ALK. After the corneal scar tissue is removed, the residual refractive error correction could be treated in another step. KAMIL BILGIHAN, MD Ankara, Turkey
f The history suggests that DLK occurred in the early postoperative period and resulted in scarring. Diffuse lamellar keratitis frequently occurs in eyes with epithelial defects. Perhaps the DLK was not diagnosed or treated aggressively enough for fear of delayed epithelial healing. As scars caused by DLK resolve slowly (2 or more years), 1 option would be to wait and place the patient on steroids (eg, fluorometholone) for a couple of months. I would also discuss the surgical option of penetrating corneal graft, especially in the right eye as it has corneal thinning and a posterior keratoconus. MICHAEL C. KNORZ, MD Mannheim, Germany
f This case probably corresponds to a severe end-stage case of grade IV DLK. This complication is more frequent after mechanical corneal deepithelialization during surgery. In this case, it was unsuccessfully treated with steroids, which left a corneal scar that extends throughout the resected flap. The topographic images of both eyes show irregular astigmatism induced by the corneal scar and by a decentered ablation. I would first try a trial of inverted aspheric gaspermeable contact lens wear. I would use maximal asphericity (around 10 to 12 points), a base curve of 39.50, and a large diameter (around 10.0 mm). This avoids lens decentration and improves stability in cases
with decentered ablations from previous laser treatments. Contact lenses with smaller diameters tend to decenter and produce halos, star bursts, and even monocular diplopia. On the other hand, diameters larger than 10.2 mm are not recommended because they would compromise lachrymal exchange. If the patient is intolerant of these new contact lenses, surgical options can be considered. One is to perform homoplastic keratomileusis using a 160 m plate in the right eye and a 200 m plate in the left eye. I recommend using a donor flap with a 0.5 m smaller diameter to avoid interface epithelialization. The flap should be sutured with an 8-pass antitorque suture that is removed 1 week postoperatively. After a minimum of 6 months, refraction should be taken and the refractive error surgically treated. A topography-assisted flyingspot laser could be used to perform LASIK in which a new flap is made under the previous one. The ablation should be based on elevation topography so one can visualize the difference in height of the central and temporal cornea. The ablation should be 6.5 mm and central, with protection to the temporal side until the cornea is level. Then, the procedure should continue until the ablation is complete. To avoid a free flap, the previous flap should not be lifted. I would recommend soft contact lens use for the first day postoperatively. A second option is to perform central 6.5 mm PTK with temporal side protection using topography-assisted flying-spot ablation until the cornea is level and then continuing with a 6.5 mm ablation until the haze disappears. The refractive result will determine whether a lamellar refractive graft should be done. Before this procedure, a corneal epithelial basement membrane defect should be ruled out. Such a defect takes several weeks to heal, and the first epithelial defect took almost 2 weeks to resolve. SALOMON ESQUENAZI, MD Bogota´, Colombia
f Unfortunately, the preoperative pachymetry is not known. The Orbscan images show a posterior corneal bulge in both eyes, more evident in right. Moreover, the anterior topographies and elevation maps show prolate corneas, not oblate such as after LASIK for myopia. The clinical and topographical images suggest an iatrogenic keratectasia in both eyes. Therefore, if the patient has difficulty tolerating RGP lenses and has se-
J CATARACT REFRACT SURG—VOL 27, JANUARY 2001
17