Combined ethanol-assisted and blunt mechanical corneal epithelial peeling technique

Transcription

1 TECHNICAL REPORT Combined ethanol-assisted and blunt mechanical corneal epithelial peeling technique Rafael Bilbao-Calabuig, MD 1 ; Félix González-López, MD 1 ; José R. Villada-Casaponsa, MD 1 ABSTRACT: We describe a new surgical maneuver combining chemical and mechanical techniques for debridement of the corneal epithelium prior to photoablation in surface laser surgery. In this procedure, a circular cellulose cell sponge soaked with 20% ethanol solution is positioned over the central cornea for 50 seconds. The adhesions between the epithelium and the corneal stroma are loosened using another weck cell spear, and finally, the central corneal epithelium is easily lifted off with the same weck cell spear in a circular manner using epitheliorhexis technique. The maneuver has been used in 838 cases, resulting in straightforward and uniform removal of the corneal epithelium with minimal patient discomfort. No intraoperative or early postoperative complications were observed. J Emmetropia 2014; 5: Although laser in situ keratomileusis (LASIK) is the most commonly performed corneal photoablative surgical refractive procedure, over the last decade a trend has emerged favoring surface ablation techniques 1,2. These techniques are less invasive and can avoid or minimize certain problems associated with LASIK such as flap or microkeratome related complications, postoperative dry eye or secondary corneal ectasia 3. However, these techniques are associated with greater postoperative pain, slower visual recovery and corneal haze and consequently both patients and surgeons are often reluctant to use these techniques 4. Several modifications have been made to the initial photorefractive (PRK) procedure in order to minimize these complications. Most alternative methods modify the means by which the corneal epithelium is removed. Initially, the procedure involved mechanical debridement using different Submitted: 3/17/2014 Revised: 7/15/2014 Accepted: 7/15/ Clínica Baviera, Instituto Oftalmológico Europeo, Madrid, Spain Financial disclosure: The authors report no financial or proprietary interest in any material or method mentioned. Corresponding Author: Rafael Bilbao-Calabuig Clínica Baviera. Pseo Castellana, 20, Madrid 28046, Spain rbilbaocalabuig@hotmail.com Communication partially presented as a video at the 30th Congress of the ESCRS, Milan (Italy) in September types of scalpel blades or rotating brushes 5,6. However, in 1999 Camellin first described the laser-assisted subepithelial keratomileusis (LASEK) technique (Ocular Surgery News, March 1999, page 28). This procedure involves the use of a cone filled with a dilute alcohol solution placed over the cornea, creating a complete flap of the epithelium 7. In contrast, in transepithelial PRK (tprk) an excimer laser is used to remove the epithelium. Meanwhile, the epi-lasik technique uses an epithelial microkeratome to separate the corneal epithelium from the underlying anterior stroma 8. There is controversy surrounding the advantages and disadvantages of each method, particularly with respect to postoperative pain, recovery of visual acuity, subepithelial scar formation, the toxic effects of alcohol and the synergistic effects with mitomycin C (MMC) 9,10,11. In this paper we report a technique whereby the corneal epithelium is peeled off prior to photoablation in surface ablation laser surgery. This technique combines both chemical and blunt mechanical processes, minimizing patient discomfort and possibly improving the safety of the procedure while using very simple surgical instruments. SURGICAL TECHNIQUE Patients received one drop of tetracaine 0.5% and preservative-free diclofenac 0.1% preoperatively. Lashes and lids were cleaned using a swab with 2014 SECOIR Sociedad Española de Cirugía Ocular Implanto-Refractiva ISSN:

2 146 COMBINED TECHNIQUE FOR CORNEAL EPITHELIAL PEELING Figure 1. A) An 8 mm circular weck cell sponge soaked in 20% alcohol solution is positioned over the central corneal surface for 50 seconds. B) If some solution leaks towards the periphery, it is dried using another weck cell spear. povidone-iodine solution (5%). A closed-loop lid speculum was then placed and another drop of tetracaine was applied. An 8 mm circular cellulose weck cell sponge soaked in 20% ethanol solution was positioned over the central corneal surface for 50 seconds. In the case of peripheral spillage the solution was dried with another weck cell spear, thus avoiding damage to limbal stem cells and irritation of the conjunctiva caused by the alcohol solution. Once the circular sponge was discarded, the surface of the eye was flushed twice with chilled balanced salt solution in order to remove residual alcohol, and the adhesion of the corneal epithelium was loosened by applying pressure with another weck cell sponge using circular movements over the central surface of the cornea. The central corneal epithelium was then easily lifted off in a circular manner using epitheliorhexis technique with the same or another weck cell spear. The epithelial flap was then discarded, however if desired, the surgeon may replace the epithelium over the stromal surface after laser ablation as the whole epithelial flap can be lifted unspoiled. The edges of the debrided area may be extended slightly towards the corneal periphery with a blunt spatula if the required area is greater than 8 mm. In the case of hyperopia, a larger 9 mm circular sponge was used. We then proceeded with photoablation using the Technolas 217z100 excimer laser (Bausch & Lomb, Rochester, NY, USA) using our standard nomogram. Following laser ablation, 0.02% MMC was applied to the ablated stroma. MMC was applied for 12 seconds when the depth of central ablation was less than 65 microns and for 20 seconds when the depth was greater than 65 microns. Eyes were then thoroughly irrigated with 50 ml of chilled balanced salt solution and a silicon hydrogel contact lens (Acuvue Oasys, Johnson & Johnson Vision Care, Inc) was placed over the cornea until complete reepithelization was achieved. Moxifloxacin 0.5% and diclofenac 0.1% eye drops were then instilled, and the patients were discharged. Postoperatively, preservative-free dexamethasone 0.1% and moxifloxacin 0.5% were prescribed every 6 hours for the first week and preservative free diclofenac 0.1% every 6 hours for 2 days. Patients also received oral analgesia with acetaminophen 1 g every 8 hours and ibuprofen 600 mg twice daily for the first 3 days. In the second postoperative week the corticosteroid treatment was changed to fluorometholone 0.1%, which was then tapered between the second and third month. Regular use of artificial tears (0.15% sodium hyaluronidate) was recommended during the first three weeks, and later as needed in accordance with the patient s symptoms. Patients were monitored every 2 days until the epithelial defect had healed completely, and bandage contact lens was then removed. A follow-up visit was performed after one week, and further visits at one, three and six months thereafter. RESULTS The blunt combined corneal epithelial peeling technique has been used extensively by many ophthalmic surgeons in our group since it was introduced in January Since then, the authors of this work have used this technique in refractive corneal surgery prior to laser photoablation in 838 cases. No intraoperative or early postoperative complications were observed, nor were any other techniques required in order to

3 COMBINED TECHNIQUE FOR CORNEAL EPITHELIAL PEELING 147 Figure 2. A) The adhesions between the epithelium and the corneal stroma are then loosened by applying some pressure using circular movements over the central surface of the cornea. B-E) The loosened central corneal epithelium is then easily lifted off with the same weck cell spear through epitheliorhexis in a circular manner. F) The epithelial flap is discarded. complete epithelial debridement. The mean time for complete reepithelization and contact lens removal was 4.8 ± 0.4 days, and did not surpass 14 days in any case. In terms of the refractive results, we did not find any significant differences with respect to previous epithelial debridement techniques, and no modifications to our previous laser nomograms were required. No eye presented with corneal haze greater than grade 1 after three months of postoperative follow-up. DISCUSSION As described previously, there are several techniques for epithelial debridement prior to corneal surface photoablation in refractive surgery. t-prk, mechanical and alcohol-assisted epithelial debridement techniques have been found to be safe and effective. Several studies have compared these procedures in terms of visual and refractive outcomes, postoperative pain, epithelial healing and haze formation, with sometimes contradictory results. In t-prk total epithelial removal using laser is difficult and in some cases areas of Bowman s membrane can be removed unintentionally. This may lead to under or overcorrection in refractive results 12. Mechanical debridement is straightforward and effective, however this process may result in damage to Bowman s layer as well as a more irregular anterior stromal surface and remaining islands of residual epithelium. In addition, mechanical debridement is a longer process and there is usually greater discomfort to the patient. Alcohol-assisted removal is perhaps easier, quicker and more comfortable for both the patient and the surgeon 13,14. However, some pressure needs to be applied with a cone over the ocular globe for seconds, and at times the 20% ethanol solution may spill towards the periphery of the cornea, particularly after involuntary ocular movements when the patient feels the pressure of the cone. The spilled solution can damage limbal stem-cells and often produces pain and important irritation of the conjunctiva. In our technique we combine the initial chemical effect of the 20% ethanol solution which loosens the corneal epithelium, with a non-traumatic mechanical effect produced by the movement of the cellulose sponge and epithelial peeling. This procedure combines the advantages of the two initial techniques while minimizing their adverse effects. The diluted alcohol separates the epithelium and corneal stroma creating a smooth and regular surface, however, in contrast to the conventional alcohol-assisted technique, no

4 148 COMBINED TECHNIQUE FOR CORNEAL EPITHELIAL PEELING Figure 3. The edges of the debrided area can be slightly extended towards the corneal periphery with the weck cell sponge or a blunt spatula before laser photoablation. pressure needs to be applied to the ocular globe and no spillage of the solution occurs, thus minimizing patient discomfort and surgical trauma to the ocular surface. The mechanical effect in this technique is produced by a blunt sponge, thus rendering the use of sharp surgical instruments (that can damage Bowman s membrane) unnecessary. In our experience, contact with the circular cellulose sponge is required for 50 seconds in order to easily loosen the corneal epithelium. When exposure time is shorter, removal of the epithelium with the weck cell sponge is often incomplete and use of other rigid surgical instruments may be required thereafter. No clinical adverse effects have been observed with this alcohol solution exposure time, which is longer than that described in previous techniques. In addition, patient tolerance is excellent as no pressure is applied to the ocular globe. The technique also allows for complete lifting of the epithelial flap which can then be repositioned over the corneal stroma after laser ablation if the surgeon considers it appropriate. Another advantage of the technique is that it does not require the use of expensive or sophisticated surgical instruments for epithelial removal. The authors have also used this maneuver in other surgical procedures in which epithelial debridement was required, for example in corneal cross-linking and phototherapeutic keratectomy for disorders of the anterior stroma, without any adverse effects or unexpected corneal reactions. CONCLUSION This technique, which involves both chemical and mechanical processes, reduces patient discomfort and is possibly a safer procedure as it does not involve the use of pressure to the globe nor the use of sharp instruments. Postoperative inflammation is also reduced due to minimal surgical trauma to the epithelium. REFERENCES 1. Pop, M, Payette Y. Photorefractive keratectomy versus laser in situ keratomileusis: a control matched study. Ophthalmology 2000; 107: Hersh PS, Brint SF, Maloney RK et al. Photorefractive keratectomy versus laser in situ keratomileusis for moderate to high myopia. A randomized prospective study. Ophthalmology 1998; 105: Melki SA, Azar DT. LASIK complications: etiology, management and prevention. Surv Ophthalmol. 2001; 46: Alio JL, Artola A, Claramonte PJ, Ayala MJ, Sánchez SP. Complications of Photorefractive keratectomy for myopia: two year follow-up of 3000 cases. J Cataract Refract Surg. 1998; 24: Pallikaris IG, Karoutis AD, Lydataky SE, Siganos DS. Rotating brush for fast removal of corneal epithelium. J Refract Corneal Surg. 1994; 10: Campos M, Hertzog L, Wang XW, Fasano AP, McDonnell PJ. Corneal surface after deepithelization using a sharp and a dull instrument. Ophthalmic Surg. 1992; 23: Litwack S, Zadok D, García de Quevedo V, Robledo N, Chayet A. Laser-assisted subepithelial keratectomy for the correction of myopia; a prospective comparative study. J Cataract Refract Surg. 2002; 28: Johnson DG, Kezirian GM, George SP, Casebeer JC, Ashton J. Removal of corneal epithelium with phototherapeutic technique during multizone, multipass photorefractive keratectomy. J Refract Surg. 1998; 14: Shah S, Doyle SJ, Chaterjee A, Williams BE, Ilango B. Comparison of 18% ethanol and mechanical debridement for epithelial removal before photorefractive keratectomy. J Refract Surg. 1998; 14(2 Suppl):S212-S Kanitkar KD, Camp J, Humble H, Shen DJ, Wang MX. Pain after epithelial removal by ethanol-assisted mechanical versus transepithelial excimer laser debridement. J Refract Surg. 2000; 16:

5 COMBINED TECHNIQUE FOR CORNEAL EPITHELIAL PEELING Blake CR, Cervantes-Castañeda RA, Macias-Rodríguez Y, Anzoulatous G, Anderson R, Chayet A. Comparison of postoperative pain in patients following photorefractive keratectomy versus advanced surface ablation. J Cataract Refract Surg. 2005; 31: Lee HK, Lee KS, Kim JK, Kim HC, Seo KR, Kim EK. Epithelial healing and clinical outcomes in excimer laser photorefractive surgery following three epithelial removal techniques: Mechanical, alcohol and excimer laser. Am J Ophthalmol. 2005; 139: Ghoreishi M, Attarzadeh H, Tavakoli M, Moini HA, Zandi A, Masjedi A et al. Alcohol-assisted versus mechanical epithelium removal in photorefractive keratectomy. J Ophthalmic Vis Res. 2010; 5: Einollahi B, Baradaran-Rafii A, Rezaei-Kanavi M et al. Mechanical versus alcohol assisted epithelial debridement during photorefractive keratectomy: a confocal microscopic clinical trial. J Refract Surg. 2011; 27: First author: Rafael Bilbao-Calabuig, MD Clínica Baviera Madrid, Spain