|Year : 2020 | Volume
| Issue : 2 | Page : 108-112
Femtosecond laser-assisted anterior lamellar keratoplasty for treatment of herpetic corneal scars
Mohamed Anis, Mohamed Hosny, Sarah Azzam
Department of Ophthalmology, Faculty of Medicine, Cairo University, Cairo, Egypt
|Date of Submission||02-Feb-2020|
|Date of Decision||14-Mar-2020|
|Date of Acceptance||29-Mar-2020|
|Date of Web Publication||26-Jun-2020|
MD, FRCS Sarah Azzam
Department of Ophthalmology, Cairo University, 50 Gezirat El Arab Street, Mohandeseen, Giza 12411
Source of Support: None, Conflict of Interest: None
Purpose The aim of this study was to report the results of femtosecond laser-assisted anterior lamellar keratoplasty (FS-ALK) for treatment of herpetic corneal scars in a small group of cases.
Patients and methods A noncomparative case series of eight eyes with postherpetic stromal corneal scars underwent FS-ALK using the Alcon WaveLight FS-200. The donor and recipient corneas were cut using the same parameters at 70% depth from the thinnest location of the recipient cornea. The donor cornea was sutured using eight interrupted sutures. The main outcome measures included preoperative and postoperative uncorrected visual acuity and best-corrected visual acuity (BCVA, LogMar). Anterior segment optical coherence tomography was done preoperatively and 1 month after suture removal. Complications were documented.
Results The procedure was uneventful in all eyes with easy separation of the precut lenticule with no intraoperative complications. The BCVA improved significantly in 7/8 (87.5%) eyes. The mean preoperative BCVA was 0.88±0.15 LogMar and improved 1 month after suture removal to 0.36±0.15 LogMar (P=0.00001).
Conclusion The FS-ALK is a safe, easy, and effective procedure for the treatment of herpetic corneal scars.
Keywords: corneal scars, femto, herpetic keratitis, lamellar keratoplasty
|How to cite this article:|
Anis M, Hosny M, Azzam S. Femtosecond laser-assisted anterior lamellar keratoplasty for treatment of herpetic corneal scars. Delta J Ophthalmol 2020;21:108-12
|How to cite this URL:|
Anis M, Hosny M, Azzam S. Femtosecond laser-assisted anterior lamellar keratoplasty for treatment of herpetic corneal scars. Delta J Ophthalmol [serial online] 2020 [cited 2020 Sep 22];21:108-12. Available from: http://www.djo.eg.net/text.asp?2020/21/2/108/287467
| Introduction|| |
Ever since the first successful allograft corneal transplant by Zirm in 1905, the possibility of replacing a layer of the cornea has been a quest . This was achieved by the work of Barraquer in the 1950s as he introduced the anterior lamellar keratoplasty (ALK) with the main aim of refractive error correction . ALK has been suggested for anterior corneal stromal opacities as it avoids the transplantation of the main antigenic load (endothelium) and thus prevents allograft rejection and minimizes the intraoperative complications. This technique has been frowned upon over the years owing to the substandard visual results ,,. The long visual rehabilitation and the unfavorable final best-corrected visual acuity (BCVA) were attributed to interface irregularities and the nonmatching of donor and recipient corneal collagen beam arrangement . This consensus was further endorsed by the introduction of deep anterior lamellar keratoplasty (DALK), a procedure that avoids the stroma-to-stroma optical interference and hence yielded good results . Over the years, in spite of good results, studies began to emerge that changed slightly how we look at DALK surgery. Reports of excellent visual outcome were associated with DALK surgery that left a thin layer of stroma ,. Other reports attributed bad visual outcomes after DALK surgeries to remnants of recipient stroma at the circumference leading to irregular interface . So, the regularity of the interface seems an important issue, even if the Descemet’s membrane is not totally bared. This regularity could not be achieved by manual dissection using sharp instruments .
Herpetic stromal keratitis is a potentially blinding disease caused by herpes simplex virus corneal infection. Most cases of herpetic stromal keratitis are due to reactivation of the virus from latency leading to recurrent bouts of corneal inflammation and scarring with progressive loss of vision .
The aim of this study was to report the results of eight cases of herpetic corneal scars treated with femtosecond laser-assisted anterior lamellar keratoplasty (FS-ALK) aiming at replacement of 70% of corneal stromal thickness. The rationale was that the femtosecond laser will create a regular interface and a perfect match. More than 70% depth would affect smoothness of the interface.
| Patients and methods|| |
Eight eyes of eight patients (one female and seven males) aged 38–42 years, with postherpetic corneal scars for whom ALK was performed, were recruited for the study. The study was approved by the Local Ethical Committee of Dar El Oyoun Specialized Eye Hospitals. Patients were informed about the procedure and the risks of the surgery and signed a written informed consent to participate in the study and for publication of data before enrollment in the study. All procedures were performed by a single surgeon (M.H.).
All treated eyes had a preoperative and postoperative examination at the clinic. The uncorrected visual acuity and BCVA were measured using Snellen’s chart. Slit lamp was used to examine the cornea and anterior segment. Eyes with active keratitis were excluded from the study. Intraocular tension was measured using the air puff tonometer (Nidek NT-510; Hiroishi, Gamagori, AICHI, Japan). Fundus examination was done by 90 D lens indirect ophthalmoscopy. Ocular ultrasound was done for eyes with hazy view to exclude cases of glaucoma and posterior segment pathology.
Anterior segment optical coherence tomography (OCT) was performed by the Heidelberg Spectralis OCT, Anterior Segment Module (Heidelberg Engineering, GmbH, Germany), to measure the corneal diameter and the depth of the scar. Eyes with endothelial pathology were excluded from the study. OCT was done preoperatively and 1 month after suture removal in all eyes.
Benoxinate hydrochloride 0.4% eye drops (Benox; Eipico Inc., Cairo, Egypt) were instilled in the recipient eye. The 200 kHz WaveLight FS-200 Femtosecond Laser machine (Alcon, Texas, USA) was used to cut the recipient cornea at 70% depth from the thinnest location. The corneal thickness was calculated as the mean average between the OCT reading and the online pachymetry. The diameter of the cut was between 7 and 8 mm according to the corneal scar measurement.
The donor cornea was examined using the slit lamp and mounted on an artificial anterior chamber and was cut by the same diameter and depth as measured for the recipient cornea.
The patient was then transferred to the operating room. Peribulbar anesthesia was given under sedation. Then the recipient corneal button was removed easily, and the donor lenticule was transferred and sutured by eight sutures ([Figure 1]a–f).
|Figure 1 (a, b, c) Removal of the precut recipient corneal button. (d, e, f) Positioning and suturing of the donor lenticule using eight interrupted sutures.|
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Postoperative treatment included topical antibiotics and steroids. The steroids were gradually withdrawn over several months.
Follow-up visits were scheduled at 1 day followed by weekly examination. Sutures were removed after 1 month on two sessions, 2 weeks apart. OCT was repeated after 1 month of suture removal.
| Results|| |
There were no intraoperative complications, and all patients had smooth and easy lamellar separation. All eyes showed uneventful postoperative course ([Figure 2]a and b).
|Figure 2 (a, b) Postoperative picture of two of the cases on the first postoperative day.|
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The BCVA improved in seven (87.5%) patients, whereas one (12.5%) patient did not improve. The mean preoperative BCVA was 0.88±0.15 LogMar. It improved 1 month after suture removal to 0.36±0.15 LogMar, with a statistically significant difference (P=0.00001, [Table 1]).
|Table 1 Best-corrected distance visual acuity preoperatively and 1 month after suture removal|
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OCT was repeated after 1 month of suture removal and showed well coaptation and a very smooth interface between the donor and recipient corneas ([Figure 3]a–c). One case showed central interface irregular opacities, which explained the nonimprovement of the BCVA in this particular case ([Figure 4]).
|Figure 3 (a) Optical coherence tomography 1 month after suture removal for patient no. 1. (b) Optical coherence tomography 1 month after suture removal for patient no. 3. (c) Optical coherence tomography 1 month after suture removal for patient no. 5.|
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|Figure 4 Optical coherence tomography 1 month after suture removal for patient no. 2, with a central dense hyperreflective opacity explaining the limited improvement of corrected distance visual acuity.|
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| Discussion|| |
Keratoplasty has always been the treatment for the postherpetic stromal scars. It started by penetrating keratoplasty with its higher risk of graft rejection. However, the ALK recently emerged as a treatment option for anterior stromal pathology being a less invasive procedure that can replace the scarred tissue ,.
In the current study, eight-sutured FS-ALK was done for eight eyes. The cut was done at a 70% depth from the thinnest location that was usually around 300 μm, as the manufacturer recommended against cutting deeper than 70%, as this would result in irregular interface. Lu et al.  in their study of FS-ALK for the treatment of stromal corneal pathology had a deeper cut at a depth up to 540 μm using 500-kHz femtosecond laser. They did not comment on the uniformity of the laser cut at that depth especially through the stromal scar. In addition, they used the conventional running suture. In the present study with a depth of 70%, eight interrupted sutures were used with the benefit of selective suture removal.
Yoo et al.  introduced the sutureless ALK with a cut ranging from 160 to 270 μm using the 500-kHz femtosecond laser, with 58.3% of cases having improved uncorrected visual acuity. However, in the current study, we reached a deeper depth with no need for adjuvant surgical steps, as they used excimer laser phototherapeutic keratectomy as an adjuvant to complete the removal of the stromal scar.In this study, there were no cases with epithelial ingrowth or graft rejection over the follow-up period of 6 months. Coster and Williams  reported that five of 20 cases were rejected and one epithelial ingrowth occurred with a mean follow-up time of 42±15 months. It is established that the incidence of rejection of grafts in postherpetic eyes is higher compared with the noninflammatory conditions.
In one case, the BCVA did not improve with stromal and interface haze, which was evident by anterior segment OCT owing to herpetic reactivation.
| Conclusion|| |
The FS-ALK is a safe, easy, and effective procedure for the treatment of herpetic corneal scars.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
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[Figure 1], [Figure 2], [Figure 3], [Figure 4]