- Email: [email protected]
Repositioning free laser in situ keratomileusis flaps
TECHNIQUE
Repositioning free laser in situ keratomileusis flaps Amit Todani, MD, Khalid Al-Arfaj, MD, Samir A. Melki, MD, PhD
We describe a protocol for adequate repositioning of free laser in situ keratomileusis (LASIK) corneal flaps created by a Moria M2 microkeratome even in the absence of fiduciary marks. In an enucleated porcine globe, a free flap was created by initially placing a longitudinal incision at the proposed hinge site followed by activating the forward pass of the automated microkeratome. A protocol was devised based on placement of a positioning dot on the free flap before the flap is retrieved from the microkeratome head. Preplaced surgical landmarks were used as a guide to determine the correct alignment of the free flap. Adequate orientation of the free flap to the stromal bed was achieved in 9 porcine eyes using the positioning dot method. The technique is applicable to the Moria M2 microkeratome only and must be validated for other types of keratomes. Financial Disclosure: No author has a financial or proprietary interest in any material or method mentioned. J Cataract Refract Surg 2010; 36:200–202 Q 2010 ASCRS and ESCRS Online Video
A free flap occurs when the laser in situ keratomileusis (LASIK) flap hinge is severed during the procedure. Common causes of microkeratome-created free flaps include inadequate suction and flat corneas, typically less than 42 diopters (D).1–4 Free LASIK flaps may also occur with femtosecond laser–created flaps if the flaps are torn during manual dissection. Fiduciary marks are typically placed to span the flap surface and the surrounding peripheral cornea, allowing adequate repositioning of free flaps. The loss or absence of marks may lead to incorrect flap orientation with serious visual consequences.3,5,6 We describe a protocol to reposition free LASIK flaps that ensures adequate repositioning even in the absence of fiduciary marks. The technique is applicable to the Moria M2 microkeratome only and must be individually validated for other types of keratomes. Submitted: March 26, 2009. Final revision submitted: September 8, 2009. Accepted: September 19, 2009. From the Massachusetts Eye & Ear Infirmary (Todani, Al-Arfaj, Melki), Boston Eye Group (Todani, Melki), Boston, Massachusetts, USA. Corresponding author: Samir A. Melki, MD, PhD, Boston Eye Group, 1101 Beacon Street, 6W, Brookline, Massachusetts 02446, USA. E-mail: [email protected].
200
Q 2010 ASCRS and ESCRS Published by Elsevier Inc.
TECHNIQUE Enucleated porcine globes and a Moria M2 automated microkeratome with a disposable head were used in this experiment. The porcine globe was positioned on a vacuum cup of a globe holder (Mastel Precision Surgical Instruments) within surgical gauze for adequate support. A free flap was attempted using a ring size of 1 and a microkeratome blade intended to obtain a 130 mm thick flap. Before the keratome pass, a 4.0 mm to 5.0 mm longitudinal corneal incision was made using a No. 11 surgical scalpel blade (SwannMorton Ltd.) at the proposed hinge site at approximately one-third corneal thickness. Radial gentian violet marks were applied using an optical zone marker (Viscot Medical LLC) to serve as surgical landmarks. Suction was then activated, and the vacuum shaft was aligned so the arrow on the suction ring pointed superiorly (0-degree reference) (Figure 1, a) toward the surgeon. This was done to ensure consistency in obtaining the hinge at the routine superior position. After a minimum vacuum pressure of 80 mm Hg was verified with a pneumotonometer (Mentor O&O, Inc.), the microkeratome head was engaged and a forward pass activated. The flap was then inspected on the superior surface of the microkeratome head (Figure 1, b). Before the flap was retrieved, a dot of gentian violet was applied to the most peripheral epithelial edge of the flap on the side facing the 0886-3350/10/$dsee front matter doi:10.1016/j.jcrs.2009.09.028
TECHNIQUE: FREE LASIK FLAPS
201
Figure 1. Creation of a free LASIK flap with an automated microkeratome. a: Following placement of a longitudinal corneal incision at the proposed hinge site, the vacuum shaft is aligned so the arrow on the suction ring points superiorly (12 o’clock position). b: The free flap is inspected on the superior surface of the microkeratome head. c: A dot of gentian violet is applied to the most peripheral epithelial edge of the flap on the side facing the surgeon. d: After the flap is retrieved, it is placed on the corneal bed, epithelial side up. A Mendez degree gauge is placed on the cornea with the zero degree reference mark aligned at the 12 o’clock position (corresponding to the position of the arrow on the suction ring).
surgeon (Figure 1, C) (Video). The flap was then carefully pulled out of the microkeratome head with a jewelers forceps and placed directly on the cornea with the epithelial side up. A Mendez degree gauge (Katena Products, Inc.) was placed on the cornea with the 0-degree reference mark aligned at the 12 o’clock position (Figure 1, d). This corresponded to the location of the arrow on the suction ring. This convention was chosen to ensure proper alignment irrespective of the operative eye and to avoid confusion when operating on right or left eyes. The free flap was then rotated until the previously applied surgical marks on the flap matched the marks in the peripheral cornea. The final orientation of the dot on the flap with respect to the Mendez degree gauge was noted in each case.
Results This technique was performed in 9 enucleated porcine eyes. On alignment of the free flap via the preplaced surgical landmarks in all eyes, the final orientation of the positioning dot on the flap consistently corresponded to the arrow etched on the Moria suction ring. If the 0 degree on the Mendez degree gauge was aligned with the arrow position on the suction ring (indicating 12 o’clock on the cornea), the positioning dot consistently corresponded to the 170 degree G 10 (SD) position diametrically opposed to the arrow position (Figure 1, d).
DISCUSSION Repositioning a free flap during LASIK is relatively simple when reference ink marks are in place.7 In some situations, the marks may not have been placed or may have faded during the procedure. Similarly, if a small free flap is obtained, the marks may be too peripheral and do not straddle the flap edge. In the absence of reference marks, positioning a circular flap in the correct orientation becomes quite difficult. An incorrectly repositioned flap may lead to severe loss of vision.3 The method we describe can be used to reposition the flap in its original orientation regardless of the presence or absence of reference marks. The first step involves recognizing the complication and preserving the LASIK flap. As a general rule, the assisting staff should not discard or disassemble the microkeratome head before being given permission to do so by the operating surgeon. If a free flap is noted, it is safer to assume absence of reference marks and act accordingly before removing the flap from the keratome. The keratome head is inspected and the flap located. The flap is gently flattened if it is rolled, avoiding rotation. A gentian violet dot is then placed at the outermost edge of the flap protruding from the microkeratome head. The flap is retrieved from the keratome head using a nontoothed forceps. It is placed on the corneal bed epithelial side up with the dot matching the arrow position of the
J CATARACT REFRACT SURG - VOL 36, FEBRUARY 2010
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TECHNIQUE: FREE LASIK FLAPS
suction ring used to cut the flap. The latter typically corresponds to the 12 o’clock position. For more accurate placement, a quick review of a video recording of the procedure, if available, will indicate the exact position of the arrow in that particular case. A Mendez degree gauge (or an equivalent instrument) is placed at the limbus with the 0-degree mark aligned to the ink dot. The flap is then rotated until the dot matches the 170-degree mark diametrically opposed to the 0-degree mark of the astigmatic dial. The occurrence of a free flap does not preclude excimer laser ablation if the exposed stromal bed is of adequate diameter in relation to the ablation zone.7,8 If ablation is to be performed, it may be preferable to delay it to allow proper flap alignment first and placement of additional fiduciary marks. The flap can then be removed and placed epithelial side down in an antidesiccation chamber during the ablation.2 Alternatively, it can be kept between 2 moist methylcellulose sponges. After excimer laser ablation, the free flap is properly positioned and allowed to air dry for at least 5 minutes for adequate reattachment to the stromal bed.9 This is followed by careful biomicroscopic inspection of the flap position at least 1 hour after surgery. Use of a pressure patch, insertion of a bandage contact lens,5,8 or suturing the flap7 may be considered. Pressure patching or a poorly fitted contact lens may result in flap dislodgement.6,8 Although sutures secure the flap, they may induce flap folds, epithelial ingrowth, and irregular astigmatism.9,10 Alternatively, a loose suture can be placed at the 12 o’clock position and the eyelid gently taped until the patient is examined the next day to avoid total loss of the flap.5 A protective shield is placed to protect the lid from external trauma.7,9 In conclusion, correct repositioning of a free flap in the absence of reference marks is possible. The method
described for the Moria M2 microkeratome must be individually validated for other types of keratomes. REFERENCES 1. Melki SA, Azar DT. LASIK complications: etiology, management, and prevention. Surv Ophthalmol 2001; 46:95–116 2. Gimbel HV. Flap complications of lamellar refractive surgery [editorial]. Am J Ophthalmol 1999; 127:202–204 3. Hovanesian JA, Maloney RK. Treating astigmatism after a free laser in situ keratomileusis cap by rotating the cap. J Cataract Refract Surg 2005; 31:1870–1876 4. Geggel HS. Treatment of lost flaps and slipped flaps. Int Ophthalmol Clin 2008; 48(1):65–71 5. Utz VM, Krueger RR. Management of irregular astigmatism following rotationally disoriented free cap after LASIK. J Refract Surg 2008; 24:383–391 6. Wilson SE. LASIK: management of common complications. Cornea 1998; 17:459–467 7. Fogla R, Padmanabhan P. Interrupted sutures at the hinge site to manage a free flap during laser in situ keratomileusis. J Cataract Refract Surg 2004; 30:2235–2238 8. Gimbel HV, Anderson Penno EE, van Westenbrugge JA, Ferensowicz M, Furlong MT. Incidence and management of intraoperative and early postoperative complications in 1000 consecutive laser in situ keratomileusis cases. Ophthalmology 1998; 105:1839–1847; discussion by TE Clinch, 1847–1848 9. Eggink FAGJ, Eggink CA, Beekhuis WH. Postoperative management and follow-up after corneal flap loss following laser in situ keratomileusis. J Cataract Refract Surg 2002; 28:175–179 10. Kim EK, Choe CM, Kang SJ, Kim HB. Management of detached lenticule after in situ keratomileusis. J Refract Surg 1996; 12:175–179
J CATARACT REFRACT SURG - VOL 36, FEBRUARY 2010
First author: Amit Todani, MD Massachusetts Eye and Ear Infirmary, Cornea & Refractive Surgery, Boston, Massachusetts, USA
Repositioning free laser in situ keratomileusis flaps Amit Todani, MD, Khalid Al-Arfaj, MD, Samir A. Melki, MD, PhD
We describe a protocol for adequate repositioning of free laser in situ keratomileusis (LASIK) corneal flaps created by a Moria M2 microkeratome even in the absence of fiduciary marks. In an enucleated porcine globe, a free flap was created by initially placing a longitudinal incision at the proposed hinge site followed by activating the forward pass of the automated microkeratome. A protocol was devised based on placement of a positioning dot on the free flap before the flap is retrieved from the microkeratome head. Preplaced surgical landmarks were used as a guide to determine the correct alignment of the free flap. Adequate orientation of the free flap to the stromal bed was achieved in 9 porcine eyes using the positioning dot method. The technique is applicable to the Moria M2 microkeratome only and must be validated for other types of keratomes. Financial Disclosure: No author has a financial or proprietary interest in any material or method mentioned. J Cataract Refract Surg 2010; 36:200–202 Q 2010 ASCRS and ESCRS Online Video
A free flap occurs when the laser in situ keratomileusis (LASIK) flap hinge is severed during the procedure. Common causes of microkeratome-created free flaps include inadequate suction and flat corneas, typically less than 42 diopters (D).1–4 Free LASIK flaps may also occur with femtosecond laser–created flaps if the flaps are torn during manual dissection. Fiduciary marks are typically placed to span the flap surface and the surrounding peripheral cornea, allowing adequate repositioning of free flaps. The loss or absence of marks may lead to incorrect flap orientation with serious visual consequences.3,5,6 We describe a protocol to reposition free LASIK flaps that ensures adequate repositioning even in the absence of fiduciary marks. The technique is applicable to the Moria M2 microkeratome only and must be individually validated for other types of keratomes. Submitted: March 26, 2009. Final revision submitted: September 8, 2009. Accepted: September 19, 2009. From the Massachusetts Eye & Ear Infirmary (Todani, Al-Arfaj, Melki), Boston Eye Group (Todani, Melki), Boston, Massachusetts, USA. Corresponding author: Samir A. Melki, MD, PhD, Boston Eye Group, 1101 Beacon Street, 6W, Brookline, Massachusetts 02446, USA. E-mail: [email protected].
200
Q 2010 ASCRS and ESCRS Published by Elsevier Inc.
TECHNIQUE Enucleated porcine globes and a Moria M2 automated microkeratome with a disposable head were used in this experiment. The porcine globe was positioned on a vacuum cup of a globe holder (Mastel Precision Surgical Instruments) within surgical gauze for adequate support. A free flap was attempted using a ring size of 1 and a microkeratome blade intended to obtain a 130 mm thick flap. Before the keratome pass, a 4.0 mm to 5.0 mm longitudinal corneal incision was made using a No. 11 surgical scalpel blade (SwannMorton Ltd.) at the proposed hinge site at approximately one-third corneal thickness. Radial gentian violet marks were applied using an optical zone marker (Viscot Medical LLC) to serve as surgical landmarks. Suction was then activated, and the vacuum shaft was aligned so the arrow on the suction ring pointed superiorly (0-degree reference) (Figure 1, a) toward the surgeon. This was done to ensure consistency in obtaining the hinge at the routine superior position. After a minimum vacuum pressure of 80 mm Hg was verified with a pneumotonometer (Mentor O&O, Inc.), the microkeratome head was engaged and a forward pass activated. The flap was then inspected on the superior surface of the microkeratome head (Figure 1, b). Before the flap was retrieved, a dot of gentian violet was applied to the most peripheral epithelial edge of the flap on the side facing the 0886-3350/10/$dsee front matter doi:10.1016/j.jcrs.2009.09.028
TECHNIQUE: FREE LASIK FLAPS
201
Figure 1. Creation of a free LASIK flap with an automated microkeratome. a: Following placement of a longitudinal corneal incision at the proposed hinge site, the vacuum shaft is aligned so the arrow on the suction ring points superiorly (12 o’clock position). b: The free flap is inspected on the superior surface of the microkeratome head. c: A dot of gentian violet is applied to the most peripheral epithelial edge of the flap on the side facing the surgeon. d: After the flap is retrieved, it is placed on the corneal bed, epithelial side up. A Mendez degree gauge is placed on the cornea with the zero degree reference mark aligned at the 12 o’clock position (corresponding to the position of the arrow on the suction ring).
surgeon (Figure 1, C) (Video). The flap was then carefully pulled out of the microkeratome head with a jewelers forceps and placed directly on the cornea with the epithelial side up. A Mendez degree gauge (Katena Products, Inc.) was placed on the cornea with the 0-degree reference mark aligned at the 12 o’clock position (Figure 1, d). This corresponded to the location of the arrow on the suction ring. This convention was chosen to ensure proper alignment irrespective of the operative eye and to avoid confusion when operating on right or left eyes. The free flap was then rotated until the previously applied surgical marks on the flap matched the marks in the peripheral cornea. The final orientation of the dot on the flap with respect to the Mendez degree gauge was noted in each case.
Results This technique was performed in 9 enucleated porcine eyes. On alignment of the free flap via the preplaced surgical landmarks in all eyes, the final orientation of the positioning dot on the flap consistently corresponded to the arrow etched on the Moria suction ring. If the 0 degree on the Mendez degree gauge was aligned with the arrow position on the suction ring (indicating 12 o’clock on the cornea), the positioning dot consistently corresponded to the 170 degree G 10 (SD) position diametrically opposed to the arrow position (Figure 1, d).
DISCUSSION Repositioning a free flap during LASIK is relatively simple when reference ink marks are in place.7 In some situations, the marks may not have been placed or may have faded during the procedure. Similarly, if a small free flap is obtained, the marks may be too peripheral and do not straddle the flap edge. In the absence of reference marks, positioning a circular flap in the correct orientation becomes quite difficult. An incorrectly repositioned flap may lead to severe loss of vision.3 The method we describe can be used to reposition the flap in its original orientation regardless of the presence or absence of reference marks. The first step involves recognizing the complication and preserving the LASIK flap. As a general rule, the assisting staff should not discard or disassemble the microkeratome head before being given permission to do so by the operating surgeon. If a free flap is noted, it is safer to assume absence of reference marks and act accordingly before removing the flap from the keratome. The keratome head is inspected and the flap located. The flap is gently flattened if it is rolled, avoiding rotation. A gentian violet dot is then placed at the outermost edge of the flap protruding from the microkeratome head. The flap is retrieved from the keratome head using a nontoothed forceps. It is placed on the corneal bed epithelial side up with the dot matching the arrow position of the
J CATARACT REFRACT SURG - VOL 36, FEBRUARY 2010
202
TECHNIQUE: FREE LASIK FLAPS
suction ring used to cut the flap. The latter typically corresponds to the 12 o’clock position. For more accurate placement, a quick review of a video recording of the procedure, if available, will indicate the exact position of the arrow in that particular case. A Mendez degree gauge (or an equivalent instrument) is placed at the limbus with the 0-degree mark aligned to the ink dot. The flap is then rotated until the dot matches the 170-degree mark diametrically opposed to the 0-degree mark of the astigmatic dial. The occurrence of a free flap does not preclude excimer laser ablation if the exposed stromal bed is of adequate diameter in relation to the ablation zone.7,8 If ablation is to be performed, it may be preferable to delay it to allow proper flap alignment first and placement of additional fiduciary marks. The flap can then be removed and placed epithelial side down in an antidesiccation chamber during the ablation.2 Alternatively, it can be kept between 2 moist methylcellulose sponges. After excimer laser ablation, the free flap is properly positioned and allowed to air dry for at least 5 minutes for adequate reattachment to the stromal bed.9 This is followed by careful biomicroscopic inspection of the flap position at least 1 hour after surgery. Use of a pressure patch, insertion of a bandage contact lens,5,8 or suturing the flap7 may be considered. Pressure patching or a poorly fitted contact lens may result in flap dislodgement.6,8 Although sutures secure the flap, they may induce flap folds, epithelial ingrowth, and irregular astigmatism.9,10 Alternatively, a loose suture can be placed at the 12 o’clock position and the eyelid gently taped until the patient is examined the next day to avoid total loss of the flap.5 A protective shield is placed to protect the lid from external trauma.7,9 In conclusion, correct repositioning of a free flap in the absence of reference marks is possible. The method
described for the Moria M2 microkeratome must be individually validated for other types of keratomes. REFERENCES 1. Melki SA, Azar DT. LASIK complications: etiology, management, and prevention. Surv Ophthalmol 2001; 46:95–116 2. Gimbel HV. Flap complications of lamellar refractive surgery [editorial]. Am J Ophthalmol 1999; 127:202–204 3. Hovanesian JA, Maloney RK. Treating astigmatism after a free laser in situ keratomileusis cap by rotating the cap. J Cataract Refract Surg 2005; 31:1870–1876 4. Geggel HS. Treatment of lost flaps and slipped flaps. Int Ophthalmol Clin 2008; 48(1):65–71 5. Utz VM, Krueger RR. Management of irregular astigmatism following rotationally disoriented free cap after LASIK. J Refract Surg 2008; 24:383–391 6. Wilson SE. LASIK: management of common complications. Cornea 1998; 17:459–467 7. Fogla R, Padmanabhan P. Interrupted sutures at the hinge site to manage a free flap during laser in situ keratomileusis. J Cataract Refract Surg 2004; 30:2235–2238 8. Gimbel HV, Anderson Penno EE, van Westenbrugge JA, Ferensowicz M, Furlong MT. Incidence and management of intraoperative and early postoperative complications in 1000 consecutive laser in situ keratomileusis cases. Ophthalmology 1998; 105:1839–1847; discussion by TE Clinch, 1847–1848 9. Eggink FAGJ, Eggink CA, Beekhuis WH. Postoperative management and follow-up after corneal flap loss following laser in situ keratomileusis. J Cataract Refract Surg 2002; 28:175–179 10. Kim EK, Choe CM, Kang SJ, Kim HB. Management of detached lenticule after in situ keratomileusis. J Refract Surg 1996; 12:175–179
J CATARACT REFRACT SURG - VOL 36, FEBRUARY 2010
First author: Amit Todani, MD Massachusetts Eye and Ear Infirmary, Cornea & Refractive Surgery, Boston, Massachusetts, USA