LASIK Fundamentals, Surgical Techniques, and Complications - part 10 pps

sions, especially with LASIK, and would probably be better PRK candidates. In fact, sur- face excimer laser ablation is one of the modalities used to treat patients with recurrent ero- sion syndrome (111–115). 1. Intraoperative Management If an epithelial defect is noted intraoperatively, a higher index of suspicion for epithelial in- growth should be maintained (Figs. 32.12 and 32.13). An attempt at repositioning the loose epithelium should be performed (Table 7). Carefully piecing the loose edges together may sometimes prove to be very challenging. Alternatively, the epithelium can be gently 454 Roque et al. Table 7 Management of Epithelial Tears/Defects/Edema Long-term Types Acute intervention Follow-up management Outcomes Epithelial tear Reposition the epithelium Observe for epithelial Lubrication Good if possible ingrowth and infection Aggressive topical steroids for DLK prophylaxis Epithelial Replace all adherent and Lubrication Remove Good defect loose epithelium and Prophylaxis for BCL after place a bandage contact infection with adequate lens antibiotics lubrication Treatment of pain with BCL, topical NSAID Aggressive topical steroids for DLK prophylaxis Stromal Gentle pressure on the Aggressive topical Slight haze if Good edema flap with a microsponge steroids for DLK persistent or blunt spatula prophylaxis stromal edema Stretched Gentle replacement of Lubrication Routine Good flap epithelium and eliminate redundant epithelium is rarely required Bandage contact lens if necessary Shrinked/ Distend the flap with care Lubrication Routine Good contracted Lift and rehydrate the flap flap Suturing as needed Prevention 1. Consider PRK in patients with anterior membrane dystrophy and symptoms consistent with recurrent corneal erosion syndrome. 2. Avoid excessive use of topical anesthetic as it may loosen the epithelium; use a glycerin-based preparation such as Proparacaine. 3. Place minimal fiducial marks and avoid the central 3.0 mm of cornea. debrided and a contact lens applied (116–118). These measures help in pain control as well as improving flap adherence and preventing epithelial cell infiltration. 2. Postoperative Management Topical nonsteroidal anti-inflammatory drugs (NSAIDS) may also be useful to ease the as- sociated discomfort (119–125). A bandage contact lens may be placed in order to prevent the lids from abrading the cornea and enlarging the epithelial defect. Caution should be ex- ercised when the contact lens is removed because of the risk of flap dislocation upon its removal. 3. Prevention Candidates for LASIK surgery should be questioned for prior history or symptoms of re- current erosion syndrome. Slit lamp examination should include careful inspection of the epithelial surface for signs of ABMD. Even when the corneal surface appears clear, nega- tive or asymmetric fluorescein staining should alert the observer to an abnormality in corneal surface integrity. Some investigators recommend touching the corneal epithelium at the slit lamp with a microsponge applicator in patients with suspected loose epithelium. If movable epithelium is noted, PRK may be a more appropriate procedure. Anecdotal re- ports of delaying preoperative topical anesthesia on the cornea until just prior to the place- ment of the microkeratome may help protect the integrity of the corneal epithelium. J. EDEMATOUS FLAPS An edematous flap is sometimes associated with poor adhesion to the underlying stromal bed. Flap decentration or displacement may occur. This has been named the floating flap phenomenon (43). The main etiology is prolonged manipulation and fluid irrigation. 4. Intraoperative Management Attempting to stroke the flap gently with a moist microsponge or a blunt spatula to displace the excess fluid may help. The use of the Pineda LASIK flap iron or the Johnstone Ap- planator may be useful in flattening edematous flats. Buratto recommends using a Thorn- ton ring to stabilize the eye while fluid is being induced away from the intercellular spaces. 5. Postoperative Management Persistent LASIK flap edema in the postoperative period should alert the surgeon to the possibility of an underlying epithelial ingrowth possibly requiring surgical intervention. 6. Prevention Minimal manipulation and irrigation are the two key elements that would prevent the oc- currence of corneal flap edema. Meticulous expression of interface fluid should be per- formed whenever copious irrigation is used intraoperatively. K. SHRUNKEN FLAPS Occasionally, after an otherwise uneventful LASIK surgical procedure a groove or gutter along the incision line is seen. We believe that this phenomenon of corneal flap shrinkage is a common yet underreported complication of LASIK surgery. Management of Flap Complications in LASIK 455 It is theorized that there are corneal tension lines that exert forces on the cornea that influence its configuration. This is clearly displayed by the gap that is sometimes seen af- ter replacement of the corneal flap. A noticeable groove may be visualized despite the best efforts in replacing the corneal flap to its original location. More commonly, corneal shrinkage may be due to the corneal flap becoming edematous and subsequently thicken- ing with resultant shrinkage in its diameter and circumference. Ironically, flap dehydration will also cause flap shrinkage. Delays during surgery will cause excessive dryness of the flap, which will cause it to shrink. Corneal flap stretching, on the other hand, is mostly brought about by prolonged ma- nipulation by an overeager surgeon. Excessive smoothing and flap positioning may con- tribute to the production of an aberrantly enlarged flap. Actually, epithelial defects may also be caused by these same faulty practices. Having an enlarged flap may actually produce a redundant epithelium. Difficulty in replacing the epithelium may be encountered. There may also be the production of some striae that may affect vision, especially if it is found centrally. 1. Intraoperative Management It is rarely necessary for any intervention to be done in order to address the phenomenon of flap shrinkage (Table 7). Simple steps may be done in order to attempt to remedy the situ- ation. The flap may be gently stretched and distended. This may be done by refloating the flap and rehydrating it once more. Additional smoothing and positioning exercises may be instituted in the hope that the rehydration will contribute to flap size normalization. Strate- gies used in the management of wrinkled flaps may be used in addressing this peculiar com- plication (Table 5). Suturing of the shrunken flap is rarely necessary but is an option. A ban- dage contact lens may be necessary in some cases in order to lessen the opportunity of ocular debris incisipating in between the corneal interface. Adequate topical antibiotic cov- erage is recommended. See Table 7 for a summary of steps to undertake. Intraoperative management of a stretched flap entails gentle repositioning of the flap, approximating as natural a position as possible. In cases of stretched flaps, redundant ep- ithelium is almost always present. Gentle repositioning of epithelium should be carried out. Redundant epithelium may be subjected to amputation in some cases, although it is rarely necessary. A bandage contact lens may be placed if necessary. Caution should be taken in removing this contact lens because of the risk of displacing the epithelium or the flap. 2. Postoperative Management Shrunken and contracted flaps should be continuously exposed to generous amounts of lu- brication. The possibility of epithelial ingrowth or debris in the interface is higher in these cases. The surgeon should be vigilant in the follow-up of these patients. One should be ready to approach it as any other epithelial ingrowth case. Stretched flaps should also be given generous amounts of lubrication. There is rarely any problem with these cases in the long-term follow-up. 3. Prevention Flap shrinkage is a peculiar phenomenon. It is impossible to determine where the ocular tension lines may be found. However, in cases of previous ocular trauma and/or surgery with notable scarring, such areas may be identified. Delays in surgery should be avoided. The time between flap reflection and stromal ablation should be kept to a minimum. The time between ablation and flap repositioning should be reduced as well. Nominal manipu- 456 Roque et al. lation of the corneal flap and minimal irrigation may decrease the chances of corneal flap shrinkage. Speed is of the essence. Remember that both overhydration and dehydration may contribute to flap shrinkage. Keeping these things in check will decrease the likelihood of encountering any problem. It is interesting to note that the steps in preventing flap shrinkage also are valid in pre- venting flap stretching. We believe that following the suggestions outlined above should decrease if not eliminate the occurrence of both flap shrinkage and stretching. L. CONCLUSIONS LASIK refractive surgery is a relatively new technique with a very high success rate, in which higher standards of safety are necessary because relatively healthy eyes are placed at risk every time the procedure is performed. 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Efficacy and safety of topical diclofenac in re- ducing ocular pain after excimer photorefractive keratectomy. J Cataract Refract Surg 1996; 22:536–541. 462 Roque et al. 463 33 Management of Interlamellar Epithelium NAN WANG and DOUGLAS D. KOCH Cullen Eye Institute, Baylor College of Medicine, Houston, Texas, U.S.A. Interlamellar epithelium is a common postoperative complication of LASIK. Although treatment is generally successful, recurrences are common, and progressive forms can be sight threatening. Keys to management are prevention, early recognition, and, when indi- cated, early surgical treatment. A. INCIDENCE There is wide variation in the reported incidence of interlamellar epithelium. Farah et al. (2) reviewed all literature published between 1990 and 1997 related to LASIK and found a 4.3% cumulative incidence of interlamellar epithelium (range: 0% to 20%). Subsequent reports have noted incidences ranging from 0% (Febbraro et al. [3]) to 31% (Perez-San- tonja et al. [22]). However, the incidence is generally reported to be less than 10%, i.e., 1% by Gimbel et al. (5), 4% by Knorz et al. (13), 2.2% by Lin and Maloney (15), 7.1% by Forseto et al. (4), 3.4% by Lindstrom et al. (16), 9.1% by Stulting et al. (24), 3.3% by Lindstrom et al. (17). Indeed, three recent studies reported an incidence of less than 1%: 0.7% by Kawesch and Kezirian (11), 0.92% by Wang and Maloney (26), and 0.34% by Walker and Wilson (25). It should be noted that some of the differences among these re- ports might be attributable to the use of different criteria to define interlamellar epithe- lium. [...]... Ophthalmology 1998 ;105 :1721–1726 R Maddox, A Hatsis Shifting sands of the Sahara: interface inflammation following LASIK In: HV Gimbel, EE Anderson Penno, eds LASIK Complications: Prevention and Management Thorofare, NJ: Slack, 1999, pp 30–36 EJ Linebarger, DR Hardten, RL Lindstrom Diffuse lamellar keratitis: diagnosis and management J Cataract Refract Surg 2000;26 :107 2 107 7 SP Holland, RG Mathias, DW... (54) Pérez-Santonja et al (43) Lin and Maloney (53) Seedor et al (58) Gimbel et al (60) Kawesch and Kezirian (23) Price et al (61) Frequency of infection (cases/total) 0.15% (3/1958) 1.20% (1/83) 0.20% (1/500) 0.19% (2 /106 2) 0.12% (1/801) 0 .10% (1 /101 9) 0.02% (1/6312) (0/2142) (0/290) 0 (0/1747) 484 Khan et al Figure 34.6 Bacterial keratitis after LASIK Table 6 Microbiological Profile of Post -LASIK Infections... each by fungus and mycobacterium, and three were culture-negative Of the eight eyes with moderate visual acuity reduction, five of the infections were due to Gram-positives, one to mycobacterium, and two were culture-negative Gram-positives caused two infections in the severe acuity reduction group, three were due to fungus, three were mycobacterial, two were combined Gram-positive and mycobacterium... Refract Surg 1999;25 :100 9 101 2 H Marotta Treatment of epithelial ingrowth In L Buratto, S Brint, eds LASIK Surgical Techniques and Complications Thorofare, NJ: Slack, 2000, pp 547–553 A Marinho, MC Pinto, R Pinto, F Vaz, MC Neves LASIK for high myopia: one year experience Ophthalmic Surg Lasers 1996;27(suppl):S517–S520 J Najman-Vainer, RJ Smith, RK Maloney Interface fluid after LASIK: misleading tonometry... Eye and Ear Infirmary and Harvard Medical School, Boston, Massachusetts, U.S.A MARGARET CHANG Columbia University College of Physicians and Surgeons, New York, New York, U.S.A SANDEEP JAIN, KATHRYN COLBY, and DIMITRI T AZAR Massachusetts Eye and Ear Infirmary, Schepens Eye Research Institute, and Harvard Medical School, Boston, Massachusetts, U.S.A Over 1,000,000 laser in situ keratomileusis (LASIK) ... at the periphery and at the flap margin and may progress only mildly Visual acuity is usually Table 3 Classification of Diffuse Lamellar Keratitis (DLK) Type IA Type IB Type IIA Type IIB Center-sparing, sporadic Center-sparing, cluster Center-involved, sporadic Center-involved, cluster 480 Khan et al unaffected, and patients rarely have any complaints They tend to respond well to high-dose steroids,... (66.7%) 1/6 Fungus (16.7%) 1/6 Negative culture (16.7%) 4 /10 Gram-positive (40.0%) 4 /10 Negative culture (40.0%) 2 /10 Fungus (20.0%) No of keratoplasties Mean final Snellen VA 3/13 (23.1%) 20/42 3/6 (50.0%) 20/200 1 /10 (10. 0%) 20/55 Infectious, Inflammation, and Lamellar Keratitis 487 Table 8 Visual Outcomes of Infections by Specific Microorganisms Gram-positive No of eyes Mean final Snellen VA Fungus Mycobacterium... of 801), and Lin and Maloney (53) a frequency of 0.1% (1 of 101 9) In unpublished case series, Seedor et al (58) documented one case of microbial keratitis out of 6312 eyes (0.02%) and Miller et al (59) reported three cases of infection after LASIK in 1958 eyes (0.15%) However, several large LASIK case series have reported no infectious complications (23,60,61) (Figure 34.6) 2 Presenting Signs and Symptoms... Inflammation, and Lamellar Keratitis 485 moniae (2), Streptococcus viridans (2), Staphylococcus epidermidis (2), and Nocardia (1) Fungal infections, such as Aspergillus (2), Scedosporium (1), and Curvularia (1), were found in four (10. 3%) eyes Eight (20.5%) mycobacterial infections due to M chelonae (7) and M fortuitum (1) were found There was one combined S epidermidis and Fusarium solani infection and one... Staphylococcus and M chelonae infection Seven (17.9%) cultures were sterile 4 Risk Factors and Potential Associations of Infection Two patients were HIV-positive; both had bilateral infections after LASIK No other systemic associations were found One patient had a history of glaucoma and another had a history of blepharitis Three eyes had undergone previous radial keratotomy (RK), and one had previous RK and . recent surgical procedure by report- ing their complications and sharing their experiences with the rest of the refractive com- munity. This has allowed for continuous refinements in LASIK flap surgical. Surg 1996;12:175–179. 43. L Buratto, S Brint, eds. LASIK Surgical Techniques and Complications. 44. I Pallikaris, D Siganos. LASIK complications and management. Cornea, 2d ed. Chap. 9, pp 227–243. 45 enhancement. Re- ported rates following primary and enhancement procedures are 1.3% vs. 3.2% (Stulting et al. [24]), 8.5% vs. 31% (Perez-Santonja et al. [22]), and 0.92% vs. 1.7% (Wang and Mal- oney