Combined scraping, coagulation, and subconjunctival bevacizumab in Descemet’s stripping automated endothelial keratoplasty for bullous keratopathy patients
Chun-Chi Chiang, MD.1,2, Jane-Ming Lin, MD.1,Yi-Yu Tsai, MD., PhD1,2 1Department of Ophthalmology, China Medical University Hospital, Taichung, Taiwan
2School of Medicine, China Medical University, Taichung, Taiwan
Running head: scraping, coagulation, and subconjunctival bevacizumab in DSAEK
Correspondence to: Yi-Yu Tsai, MD., PhD, Department of Ophthalmology, China Medical University Hospital, Taichung, Taiwan
Telephone: 886-4-22052121 ext. 1141 Fax: 886-4-22059265
e-mail address: [email protected]
Financial Disclosures: The authors have no proprietary or commercial interests in any of the materials discussed in this article.
Keywords:
Abstract
Purpose: This study evaluated the clinical outcomes of a combined method of
scraping corneal epithelium, coagulating vessels and subconjunctival bevacizumab in Descemet’s stripping automated endothelial keratoplasty (DSAEK) for bullous keratopathy patients with corneal neovascularization (NV).
Methods: The study included bullous keratopathy patients undergoing DSAEK. Indications for DSAEK were: advanced pseudophakic bullous keratopathy with superficial and deep corneal vascularization, and failed corneal grafts. Patients were treated with scraping the corneal epithelium and lightly coagulating the corneal superficial stromal NV and the feeding vessels in the sclera, with a subconjunctival bevacizumab injection at the end of surgery. Subconjunctival and perilimbal
bevacizumab of dose of 2.5 mg/ 0.1 ml/ per affected quadrant was injected at the site of neovascularization in each patient at the end of surgery. One or two injections were applied. At each visit a full eye examination with photo documentation was
performed. Mean follow-up period was 32 (24-36) months.
Results: Eight eyes of 8 patients with high-risk corneal transplantation and corneal neovascularization were included in this non-comparative interventional case series. The original corneal NV disappeared in all patients immediately after surgery. No
patient in the series had recurrent corneal NV or rejection during at least 24 months follow up.
Conclusions: The combination of scraping, coagulating and bevacizumab injection in DSAEK is an effective method to treat corneal NV in corneal transplantation for bullous keratopathy.
Introduction:
Long-standing bullous keratopathy usually induces extensive corneal
neovascularization (NV) and corneal transplantation in bullous keratopathy patients with extensive corneal NV carries a high risk of graft rejection.1,2 There are several methods to treat corneal NV before corneal transplantation, such as argon laser photocoagulation, photodynamic therapy with different photosensitizers, and epithelial debridement.3,4 However, such therapies are associated with thermal or mechanical damage to the cornea, which activate the inflammatory cascade and lead to an upregulation of vascular endothelial growth factor (VEGF).4 Hence, those therapies have a high rate of vessel regeneration in the corneal stroma that becomes difficult to destroy.
Treatment using angiogenic inhibitors has become a novel method for the management of corneal superficial and stromal NV.5-7 Bevacizumab is a full-length, humanized, murine monoclonal antibody against all types of VEGF. It is approved to treat metastatic colorectal cancer,8 diabetic retinopathy,9,10 choroidal NV in pathologic myopia,11 and exudative age-related macular degeneration (ARMD).12–14 Recently, the effects of subconjunctival injection15–18 or topical usage 19-21 of bevacizumab on the inhibition of corneal NV have been reported. However, in humans, either in the form of drops22-24 or administered subconjunctivally,15, 25-26 the results of solitary
bevacizumab were either ineffective or led to only partial regression of corneal NV. Especially concerning the patient with a previously rejected vascularized graft, there was little change in the number and caliber of blood vessels.26 This was due to varying levels of expression of VEGF in established and actively growing vessels.26
Bevacizumab had the largest impact on newly developed or developing vessels, and was ineffective against previously established blood vessels.27
Hence, combined mechanical or thermal methods to destroy the established NV along with subconjunctival bevacizumab to stop new vessel growth is a reasonable method to treat corneal NV. Moreover, in animal models, bevacizumab significantly inhibited neovascularization when administered immediately after limbal injury but provided less significant regression of established neovascularization when
administered later.18,27 Hence, destroying NV and administration of bevacizumab injection should be performed simultaneously to achieve the optimal antineovascular effect.
The combination therapy was reported in two cases reports. Qian et al.28 scraped the corneal epithelium and subconjunctivally injected bevacizumab in a peripheral ulcerative keratitis in a patient with Tarrien marginal degeneration, and Gerten et al.4 used argon laser coagulation and bevacizumab injections in two corneal transplants. Their results showed that the therapy was effective and safe.
Because it is difficult to perform corneal epithelium scraping intraoperatively or argon laser coagulation preoperatively to destroy the corneal stromal NV and the feeding vessels in conjunctiva and sclera, we developed a method to eliminate the vessels in vascularized recipients of long-standing bullous keratopathy in corneal transplantation. We scraped the corneal epithelium in the corneal NV area, and then coagulated the corneal superficial stromal NV in the peripheral cornea and the feeding vessels of the corneal stromal NV in conjunctiva and sclera. After corneal transplant, we injected bevacizumab subconjunctivally. We evaluated the efficacy of this method in destroying and preventing corneal neovascularization in Descemet’s stripping automated endothelial keratoplasty (DSAEK).
Patients and Methods:
Fully informed patient consent was obtained, and the experimental status of the method and off-label use of bevacizumab was explained to all patients according to the Declaration of Helsinki. Study protocols were approved by the institutional review board of the China Medical University Hospital.
Indications for DSAEK included: pseudophakic bullous
keratopathy with vasculized cornea in six patients, and graft failure in two patients. All surgeries were performed by a single surgeon(YY Tsai). In each case, we routinely scraped the corneal epithelium in the central 8 to 9 mm diameter for better visualization, and performed peritomy and coagulation in the sclera near limbus at 6-o’oclock for anterior chamber maintainer. We additionally scraped the corneal epithelium in the corneal NV area and coagulated the peripheral corneal stromal vessels and the feeding vessels in the sclera after peritomy by coagulation pen. During corneal and scleral coagulation, the limbus was skipped.
Toward the end of the surgery, subconjunctival and perilimbal bevacizumab of dose of 2.5 mg/ 0.1 ml/ per affected quadrant was injected at the site of
neovascularization in each patient at the end of surgery, and a soft contact lens was placed in every patient undergoing DSAEK. The contact lens was removed when the corneal epithelium had completely healed. Postoperatively, patients received
levofloxacin ) four times a day for 2 week, and prednisolone acetate 1% (Allergan, CA, USA) four times a day for 1 month. After 1 month, the topical prednisolone was gradually tapered over 3 months and finally discontinued.
After corneal transplantation, all patients stayed in the hospital for four to five days and were followed up at the 1st, 2nd, 3rd, 4th, 6th and 8th week, and 3rd, 4th, 5th and 6th month postoperatively. After six months, they were followed up every two to three months.
At each visit, 2 digital corneal photographs were taken by using a Topcon digital camera attached to the slit-lamp microscope. The photographs were graded by 1 observers for extent, centricity, and density of corneal vascularization as Bahar et al described.15 Briefly, extent was defined according to the number of clock hours affected by neovascularization (score 1–12). Centricity was defined as the distance the new vessels extended from the limbus toward the visual axis. Density was graded 1–4 according to the density of neovascularization. The scores for each picture were given by the second investigator to determine the change in neovascularization extent, centricity, and density before and after surgery.
During follow up, if NV was invading the cornea over 1 mm, the patient underwent epithelial scraping, coagulation of NV, and another 0.3 ml bevacizumab subconjunctival injection. Efficacy of the anti-corneal NV method was evaluated as
the recurrence rate of corneal NV, and also how many times the patients required retreatment during the postoperative follow-up.
Results
There were 8 patients with bullous keratopathy included in this clinical trial. The 8 DSAEK patients consisted of six pseudophakic bullous keratopathy (PBK) and two failed PKP (Table 1). All of the original corneal NV disappeared after surgery (Figure 1) and no one had recurrent corneal NV during at least 24 months follow up. Six of eight patients (75%) had both superficial and deep corneal NV. A decrease of corneal NV was also observed in those patients, with regression of NV and fading of small vessels, and there was no need for another injection.
Two patients with vascularized failed corneal grafts, both were after PKP for PBK. Combined scraping, coagulation, and subconjunctival
bevacizumab led to marked regression of these vessels, and did not appear in the graft for the period of observation.
No adverse reactions have been detected to date in all patients. No rejection or chronic epithelial defect occurred.
Discussion:
Before the application of anti-VEGFs, several surgical and medical treatments were used to counter corneal NV. 2-4,28,29 Unfortunately, these treatments did not provide a good control of vessel progression and recurrence. Surgery often activates biological mediators in the inflammatory cascade and leads to an upregulation of VEGF,4, 30 so such therapies have an immediate effect but are associated with a high rate of vessel recanalization. Among medical treatments available, steroids remain the treatment of choice to control corneal neovascularization. However, steroids alone are not always effective and can contribute to adverse effects, including glaucoma, infection, and cataract formation.19
Bevacizumab has recently been compared to betamethasone, as bevacizumab is reported to be effective in the prevention of formation as well as regression of major vessels. 31 However, bevacizumab has the most prominent effect on newly developed or developing vessels, but is ineffective against previously established blood vessels.27 Because corneal NV is a chronic and progressive phenomenon and the vessels found at the time of diagnosis are a mixture of new and old vessels, a combination of surgery and bevacizumab therapy is a reasonable treatment. Surgery removes mature vessels while bevacizumab prevents vessels from growing.
Moreover, corneal NV is often mixed with epithelial and stromal NV, thus removing the corneal epithelial NV and destroying the corneal stromal NV and the feeding vessels in conjunctiva and sclera are necessary. Surgical treatments by only argon laser photocoagulation or epithelial scraping are not effective for corneal stromal NV and the feeding vessels in conjunctiva or sclera. For this reason, we scraped the epithelium, coagulated the superficial corneal stromal NV, and coagulated the feeding vessel in the sclera after peritomy. Besides, the epithelial defect after scraping the epithelium may allow the bevacizumab to easily penetrate the previous NV area. 27
Bevacizumab can be used subconjunctivally and topically, and both means were reported to have effect15-24; however, topical application of bevacizumab was found to cause spontaneous loss of corneal epithelial integrity and progression of stromal thinning.23 There were no corneal associated problems reported with subconjunctival bevacizumab, 15, 25,26 so subconjunctival bevacizumab maybe a safer option than topical bevacizumab, especially in corneal transplant.
In our report, all patients in the study needed subconjunctival bevacizumab injection once only. We hypothesized that there were fewer ocular surface complications after DSAEK than conventional penetrating keratoplasty. DSAEK maintains ocular surface innervation and curvature, and there are few sutures left in
the cornea after DSAEK, and thus decreased complications. Fewer ocular surface complications result in less ocular surface inflammation and neovascularization. Hence, DASEK patients did not need an additional bevacizumab injection after transplantation.
Ranibizumab (Lucentis; Genentech, Inc., South San Francisco, California, USA), also a humanized monoclonal antibody fragment targeting multiple isoforms of human VEGF-A, is intended for ocular use and has revolutionized the treatment for neovascular AMD. 32,33 However, the studies of ranibizumab application in anterior segment are insufficient. Although bevacizumab is generally off-label use in
ophthalmic practice, it has been wide use in many anterior segment diseases, 34,35 and these studies showed effective short-term response together with high patient
tolerance to local bevacizumab therapy. These studies offer encouraging results for the management of anterior segment neovascular disorders.34,35 Hence, in this study, we use bevacizumab for treating corneal NV in DSAEK instead of ranibizumab. Although limbal stem cell deficiency following multiple intravitreal injections has been reported,36 there was no report of limbal stem cell deficiency after
subconjunctival bevacizumab injections. In this cases series, there were no adverse effects noted in these 8 cases after at least 24 months follow-up. There is no limbal stem cell deficiency, no chronic epithelial defect or recurrent NV has been noted.
However, a larger prospective study to find the optimum dosage and application method and schedule in connection with bevacizumab and combinations with other treatments may be needed.
There is one limitation in this study. We did not have a control group. Theoretically, a control group for this study should be composed of bullous
keratopathy patients with corneal NV without combined scraping, coagulation, and subconjunctival bevacizumab injection. However, this is not ethical as corneal transplantation in these patients without removing corneal NV carries a high risk of graft rejection.Before the clinical trial, we actually had performed DSAEK in a failed PKP patient with corneal NV. Because we only scraped the corneal epithelium and coagulated the peripheral corneal NV without coagulating the feeding vessels in the sclera or subconjunctival bevacizumab injection, the corneal NV recurred within one month postoperatively. Hence, we started to trial combined scraping, coagulation, and subconjunctival bevacizumab.
To the best of our knowledge, there is no other report on the use of bevacizumab and combined methods in the treatment of corneal neovascularization in the DSAEK patients. However, there are few reports on the subconjunctival injection of
bevacizumab combined with different methods in variant corneal diseases with corneal NV (Table 2). Although the numbers are still small, these clinical studies
demonstrate that there is a beneficial effect of using combined methods with subconjunctival injection of bevacizumab in treating corneal NV. Although the vessels regression may be partial, and recurrence may occur after cessation of
treatment, repeat bevacizumab subconjunctival injections may be effective for treating recurrent NV.28, 38
In conclusion, combined scraping of the corneal epithelium, coagulating the superficial corneal stromal NV and the feeding vessels of corneal stromal NV in sclera after peritomy, along with subconjunctival bevacizumab injection is an effective method to treat corneal NV in corneal transplantation for bullous
keratopathy. DSAEK in early stage of PBK is suggested to avoid long-standing PBK associated with deep corneal NV and scar.
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Figure Legends:
Fig. 1. Anterior-segment photograph of patient 2 (PBK) (A) before the DSAEK and the combined procedure. (B) 3 months after DSAEK and the combined procedure. Patient 3 (PBK) (C) before the DSAEK and the combined procedure. (D) 5 months after the surgery. Patient 6 (failed PKP) (E) before the DSAEK and the combined
procedure. (F) 6 months after the surgery. Note the significant regression of blood vessels in all patients.
