|Year : 2014 | Volume
| Issue : 1 | Page : 41-44
Transepithelial photorefractive keratectomy with adjunctive mitomycin-C for correction of residual myopia after LASIK
Waleed A Ghobashy, Ahmad A Abdel Ghani
Department of Ophthalmology, Suez Canal University, Ismailia, Egypt
|Date of Submission||12-Sep-2013|
|Date of Acceptance||24-Jan-2014|
|Date of Web Publication||21-Jun-2014|
Waleed A Ghobashy
MD, 6# Ibrahim Alkhalil Street, Doctors Land, Ring Road, 41511, +2064, Ismailia
Source of Support: None, Conflict of Interest: None
The aim of the study was to evaluate the efficacy and safety of transepithelial photorefractive keratectomy (trans-PRK) with adjunctive mitomycin-C (MMC) over laser in-situ keratomileusis (LASIK) flaps for the treatment of residual myopia following LASIK.
Materials and methods
In this single-center, retrospective clinical study, 12 eyes of nine patients (mean age 32.67 ± 2.8 years) who were administered MMC (0.02%, 20 s) during trans-PRK for the treatment of residual myopic error with a mean spherical equivalent of -1.00 ± 0.69 D following myopic LASIK were evaluated. The retreatment procedures were performed after an average of 13.67 ± 1.15 months of primary LASIK using Schwind Amaris 500E excimer laser, with trans-PRK plate form. All patients underwent slit-lamp microscopy, manifest and cycloplegic refraction, Sirius 3D corneal analysis, merging Scheimpflug technology with Placido topography, pachymetry, pupillometry, and wavefront analysis preoperatively and postoperatively. All patients underwent follow-up on day 1, at 1 week, and at 1, 3, and 6 months.
Mean time between LASIK and PRK retreatment was 19.2 months (range 13-39 months). No intraoperative or postoperative complications occurred during primary LASIK or trans-PRK retreatment. Mean spherical equivalent refraction of attempted correction with PRK was -1.58 D (range -0.50 to -2.25 D). By the end of sixth postoperative month, the average uncorrected visual acuity improved from 0.48 (range 0.15-0.7) to 0.7 (range 0.3-1.0). All eyes showed improvement in uncorrected visual acuity. Four eyes had subjective improvement of glare symptoms. None of the eyes in the cohort developed postoperative haze or any complications.
Trans-PRK with adjunctive MMC is a safe and effective option for correction of residual myopia following LASIK.
Keywords: Trans-epithelial photorefractive keratectomy, LASIK, mitomycin-C, myopia
|How to cite this article:|
Ghobashy WA, Abdel Ghani AA. Transepithelial photorefractive keratectomy with adjunctive mitomycin-C for correction of residual myopia after LASIK. J Egypt Ophthalmol Soc 2014;107:41-4
|How to cite this URL:|
Ghobashy WA, Abdel Ghani AA. Transepithelial photorefractive keratectomy with adjunctive mitomycin-C for correction of residual myopia after LASIK. J Egypt Ophthalmol Soc [serial online] 2014 [cited 2020 Jul 12];107:41-4. Available from: http://www.jeos.eg.net/text.asp?2014/107/1/41/134949
| Introduction|| |
Laser in-situ keratomileusis (LASIK) is the preferred surgical technique for the correction of ametropia  as evidenced by numerous publications and the peer-reviewed literature . Myopic regression and the need for enhancement or retreating the patients for visual and refractive dissatisfaction is a true challenge when combined with limited corneal thickness available and/or high-order aberrations induced by flap-related complications ,,.
Transepithelial photorefractive keratectomy (trans-PRK) is a relatively new modification of the conventional PRK, in which the epithelial removal is achieved by an excimer laser instead of alcohol and manual scraping ,. This is supposed to create a smoother crater allowing relative rapid healing of the epithelium with a resulting faster visual recovery and less discomfort .
We have carried out this study to evaluate the efficacy and safety of trans-PRK with adjunctive mitomycin-C (MMC) over LASIK flaps for the treatment of residual myopia following LASIK.
| Materials and methods|| |
Patients with systemic or ocular disease that may interfere with the healing process of the cornea, such as rheumatoid arthritis, dry-eye syndrome, anterior or posterior uveitis, keratoconus, corneal dystrophy or degeneration, glaucoma, retinal diseases, lens opacity, history of severe ocular trauma, and previous ocular surgery, were excluded from the study.
In this retrospective clinical study, 12 eyes of nine patients (mean age 35.2 years) who were administered MMC (0.02%, 30-120 s) during trans-PRK for the treatment of residual error following myopic LASIK were evaluated. The retreatment procedures were performed using Schwind Amaris 500E excimer laser (Schwind Eye-Tech, Kleinostheim, Bavaria, Germany), with trans-PRK plate form (both epithelial removal and ametropia are performed in a single step) and 500-Hz excimer laser (spot size of 0.54 mm and active 5-D eye tracking) after standard disinfection and ocular draping with instillation of topical benoxinate hydrochloride 0.4% as a topical anesthetic. All patients underwent slit-lamp microscopy, manifest and cycloplegic refraction, Sirius 3D corneal analysis, merging Scheimpflug technology with Placido topography (Costuzioni Strumenti Oftalmiti, Scandicci Firenze, Italy), pachymetry, pupillometry, and wavefront analysis preoperatively and postoperatively. All patients underwent follow-up on day 1, at 1 week, and at 1, 3, and 6 months.
A topical application of MMC 0.02% (0.2 mg/ml) diluted in balanced salt solution was instilled in each eye with a microsponge placed over the ablated stroma for 15-30 s immediately after laser ablation . The corneal surface and the entire conjunctiva were then vigorously irrigated with 20 ml cold balanced salt solution to remove the residual MMC. At the end of the procedure, a bandage contact lens was applied followed by one drop of tobramycin-dexamethasone suspension 0.1%.
In both groups, patients were instructed to use topical prednisolone acetate suspension 1% four times daily, tapered over 4 weeks according to corneal haze and intraocular pressure, ketorolac tromethamine ophthalmic solution 0.4% three times daily for 2 weeks, moxifloxacin hydrochloride ophthalmic solution 0.5% four times daily for 1 week, and ibuprofen 400 mg tablet orally twice daily for 4 days .
Bandage contact lens was removed on the fourth to sixth postoperative day, guided by epithelial healing and the patient's comfort.
Uncorrected visual acuity (UCVA) and best-corrected visual acuity (BCVA) were measured using the Snellen chart on day 1, at week 1, 1 month, and 6 months along with manifest refraction by retinoscopy. Postoperative pain was assessed using visual analog scale . Occurrence of complications was documented.
At the first postoperative week, all patients were examined with a slit lamp, and the area of the epithelial defect was measured with its ruler to identify the time of complete healing.
For evaluation of haze, we used Hanna's grading scale from 0 (no haze) to 4+ (dense white corneal haze) .
Decimal values for UCVA and BCVA were used for statistical purposes. Preoperative central corneal thickness, preoperative and postoperative K-readings, optical zone of ablation, depth of ablation, and residual stromal thickness were documented using Sirius 3D corneal analysis, merging Scheimpflug technology with Placido topography.
Mean, SD, and correlation coefficient were calculated for variables.
| Results|| |
Twelve eyes (eight right eyes and four left eyes) of nine patients (nine male patients, 67%) who underwent trans-PRK with adjunctive use of MMC for correction of residual myopia after LASIK treatment for myopic astigmatism were enrolled in this retrospective study. Other demographic and clinical characteristics of the patients are shown in [Table 1].
Retreatment with trans-PRK with adjunctive MMC was performed in 12 eyes.
Before the primary LASIK procedure, the mean spherical equivalent (SE) was -6.33 ± 2.08 D (range -4.00 to -8.00 D); 1 day before retreatment, the mean loss of UCVA was 0.48 lines of Snellen visual acuity, with myopic change with a mean SE of -1.00 ± 0.69 D (range -0.38 to -1.75 D). The mean time to retreatment was 13.67 months (range 13-15 months).
The follow-up after retreatment was for 6 months and the final mean SE refraction was -0.58 ± 0.629 D (range 0 to -1.25 D); there was no final loss of BCVA.
[Table 2] shows the clinical data before the primary LASIK procedure, the interval between the LASIK and retreatment with trans-PRK, and the final clinical outcome after 6 months of follow-up.
|Table 2: Initial, pretreatment, and fi nal data of patients who underwent retreatment with transepithelial photorefractive keratectomy|
Click here to view
The mean amount of ablated cornea in the trans-PRK retreatment was 76.67 ± 13.2 μm.
After 1 month, the mean UCVA was 0.9 ± 0.17, which deteriorated to a mean of 0.87 ± 0.35 by the end of the third month and then to 0.77 ± 0.45 by the end of the sixth month. The mean BCVA was 1.00.
Corneal haze was between zero and grade II by the end of the first postoperative month, with a mean of 1.33 ± 1.54; this declined to a mean of 0.33 ± 0.57, with a range of zero to grade I, by the end of the sixth postoperative month.
Pain was recorded by all patients in the study, with a mean score of 3.67 ± 0.58 on the first day, declining to a mean score of 0.67 ± 0.57 by the end of the first week.
| Discussion|| |
The idea of correcting the residual refractive error after primary LASIK using different procedures such as LASIK with relifting of the flap and PRK was discussed previously in the literature ,,,.
The evolution of single-step trans-PRK suggests a new modality to achieve the desired correction with a theoretical faster visual recovery promised by the relatively minimal manipulation and the lack of use of alcohol, traditionally used with PRK. In addition, the work on the surface of the flap was appealing to preserve the residual stromal thickness to avoid the possible development of ectasia.
The aim of this retrospective, observational case series was to evaluate the efficacy and safety of trans-PRK with adjunctive MMC over LASIK flaps for the treatment of residual myopia following LASIK. In this study, retreatment with trans-PRK and adjunctive MMC was not associated with any significant complications. Similar results were documented by Jain et al. . In general, the visual outcomes for retreatment with trans-PRK were favorable, as the mean UCVA improved from a mean of 0.48 before retreatment to 0.77 by the end of the study. Comparable results were obtained by Beerthuizen and Siebelt  and many other authors ,,.
Our patients reached their best UCVA by the end of the first month after trans-PRK with a mean of 0.9 ± 0.17; this showed strong positive correlation (0.866) with the SE and no correlation with corneal haze (correlation coefficient = -0.5). By the end of the study, UCVA reached a mean of 0.77 ± 0.45 with strong positive correlation with the patients' SE (0.998) and strong negative correlation (-0.89) with corneal haze. These findings were in agreement with the results published by Muller et al. .
Pain was a part of postoperative period in almost all patients; however, this was tolerable and declined from a mean of 3.67 ± 0.58 on the first day to a mean of 0.67 ± 0.57 by the end of the first week. This is documented in many other studies ,,,.
| Conclusion|| |
The outcomes of this study suggest that trans-PRK with adjunctive MMC is safe, effective, and predictable in treatment of low to moderate residual myopia after LASIK.
| Acknowledgements|| |
Conflicts of interest
There are no conflicts of interest.
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[Table 1], [Table 2]