Burr-Assisted Peripheral Superficial Keratectomy for the Treatment of Persistent Symptomatic Peripheral Corneal Edema

A 77-year-old female patient was referred to our institute for the management of peripheral corneal microcystic edema in her right eye following uncomplicated cataract surgery a year prior. Her past ocular history included presence of corneal guttae and cataract surgery in both eyes.

Upon presentation, the patient complained of recurrent episodes of mild redness, pain, and discomfort in her right eye that were treated with topical lubricants and hypertonic solutions. Her best corrected visual acuity (BCVA) was 1.0 and 1.2 (decimal scale) in the right and left eye, respectively, and the intraocular pressure was within normal limits. Slit lamp examination revealed microcystic edema in the temporal periphery of the cornea, associated with an epithelial erosion inferiorly in the right eye and presence of corneal guttae bilaterally. Endothelial cell count (ECC) was 849 and 1039 cells/mm² in the right and left eye, respectively. Anterior segment optical coherence tomography (AS-OCT) (Optovue, Inc., Freemont, CA) confirmed the presence of multiple intraepithelial cysts (Fig. 1a) and increased epithelial thickness (Fig. 1b). Treatment by phototherapeutic keratectomy did not achieve long-term symptomatic relief since recurrence of the microcystic edema was noted 2 months later. Anterior stromal puncture with a fine needle was then performed, a bandage contact lens was placed, and orally administered doxycycline 50 mg once daily was prescribed. Nevertheless, further increases in corneal edema and number of microcysts were observed, accompanied by deterioration of the patient’s symptoms. For this reason, a peripheral superficial keratectomy was proposed to the patient.

The procedure was performed under local anesthesia using the diamond ophthalmic burr (The Burr, Alger Company, USA), a foreign body removal instrument that includes a diamond body spud on a low speed, low torque, battery-operated hand-held drill. After the eye was prepped and draped in a sterile manner, the corneal epithelium was removed with an ophthalmic surgical sponge, and the Bowman’s layer and the anterior stroma were polished with the diamond burr (Fig. 2a, see video 1 in the online supplementary material). A bandage contact lens (Air Optix Night & Day Aqua, Alcon) and moxifloxacin (Vigamox, Alcon Laboratories, Inc.) eye drops were placed on the cornea. Postoperative treatment included moxifloxacin (Vigamox, Alcon Laboratories, Inc.) five times per day and fluoromethalone 0.1% (FML Liquifilm, Allergan, Inc.) four times per day that were gradually tapered.

Immediate postoperative examinations revealed a small number of microcysts restricted to the inferior cornea that regressed following instillation of sodium chloride 5% and sodium hyaluronate 0.15% (ODM 5, Horus Pharma, Inc.) four times daily. Six months after the operation, the patient reported no symptoms, mild inferior stromal scarring was observed on slit lamp examination (Fig. 2b) while a limited number of epithelial microcysts and decreased epithelial thickness were noted by AS-OCT (Fig. 1c, d). Preoperative ECC was 783 cells/mm² while at 6 months postoperatively it was 657 cells/mm². BCVA of the affected eye remained 1.0 during the entire postoperative follow-up period.

A 50-year-old male patient was referred to our department for further management of persistent symptomatic corneal edema in his left eye. Past medical and surgical history were significant for bilateral advanced open angle glaucoma, filtration, and cataract surgery on both eyes. Two weeks after the cataract surgery of the left eye, he suffered a blunt trauma with iris incarceration through the main port that was repaired without complication. Three months later, the patient developed peripheral persistent symptomatic corneal edema with bullae formation in the area of prior iris incarceration and was complaining of foreign body sensation and tearing.

On presentation, BCVA was 0.8 in both eyes and intraocular pressure was 12 mmHg in both eyes under anti-glaucoma treatment. Slit lamp examination revealed peripheral inferotemporal corneal edema and a clear cornea centrally (Fig. 3a). AS-OCT examination revealed stromal edema with epithelial bullae formation (Fig. 3b) and a corneal thickness of 1112 µm in the affected area. Endothelial cell count was 2415 and 1090 cell/mm² in the right and left eye respectively.

Because of the good central vision, minimal invasive treatment options were discussed and a peripheral superficial keratectomy using the diamond burr was performed on the slit lamp with local anesthesia (see video 2 in the online supplementary material). A bandage contact lens was placed on the cornea and antibiotic treatment with moxifloxacin (Bayer AG, Germany) five times per day was prescribed until the epithelium healed.

On last follow-up examination, 6 months postoperatively, the patient was asymptomatic and BCVA of the affected eye was 0.8. Slit lamp examination revealed anterior stromal scarring in the treated region (Fig. 3c) and AS-OCT confirmed the absence of epithelial cysts or bullae (Fig. 3d). Preoperative ECC was 1090 cells/mm² while at 6 months postoperatively it was 1083 cells/mm².

Written informed consent for publication of both patients’ clinical details was obtained. An ethics committee approval was not required for the completion of this study.