Man referred for progressive vision decline
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A 67-year-old man was referred to the cornea clinic with complaints of progressive vision decline, mild pain and tearing of the right eye.
He reported blurring of his vision that made it difficult to read and see a golf ball. Of note, the patient was walking his dogs in the woods 7 days before presentation when a tree branch snapped back and struck him in his right eye. He was evaluated by an outside ophthalmologist the day after the injury and was diagnosed with traumatic iritis, for which he was started on topical steroid eye drops.
His medical history was significant for colitis, currently in remission. Medications included mesalamine and prednisolone acetate ophthalmic drops. He had LASIK surgery in both eyes approximately 20 years ago, with subsequent flap lift and enhancement in his right eye 1 year after the original LASIK surgery. Additional ocular history included blepharitis and myopia. He was an everyday smoker and marijuana user but denied alcohol use. Family history was noncontributory.
Examination
Upon presentation, the patient’s uncorrected visual acuity was 20/200 in the right eye and 20/40 in the left eye. The pupils were briskly reactive bilaterally with no afferent pupillary defect. IOPs were normal at 11 mm Hg in the right eye and 14 mm Hg in the left eye.
The corneal examination revealed multiple scattered grayish-white opacities at the LASIK flap interface centrally in the right eye and peripherally at 6 o’clock in the left eye (Figure 1). There was no evidence of LASIK flap dislocation or flap edge lift. The cornea had no epithelial defects or fluorescein staining. The conjunctiva was white, and there was no anterior chamber cell or flare. Dilated examination was unremarkable.
Source: Yi Ling Dai, MD, and Naveen K. Rao, MD
What is your diagnosis?
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Decline in vision
With a recent history of eye trauma with organic/vegetative matter, it is imperative to consider infectious keratitis, especially fungal keratitis.
The patient was on steroid eye drops for traumatic iritis, and this can mask the typical inflammatory response of infectious keratitis. Patients can present clinically with a relatively white and quiet eye, as was the case in this patient. However, his corneal opacities did not appear infiltrative and were localized to the LASIK flap interface. Epithelial ingrowth is a complication after LASIK, and the corneal appearance was classic for the nests and islands of epithelial cells typically seen with epithelial ingrowth. Epithelial ingrowth may present within weeks to months after LASIK surgery, but late epithelial ingrowth may also occur, especially after eye trauma. Diffuse lamellar keratitis is another postoperative complication of LASIK and usually occurs within 24 hours of surgery. This is lower on the differential in terms of both the time course and clinical characteristics, as patients usually have a characteristic grainy or “sands of Sahara” appearance of the cornea.
Workup and management
Anterior segment OCT (AS-OCT) was performed and demonstrated hyperreflectivity at the LASIK flap interface at the areas of the corneal opacities, consistent with epithelial ingrowth (Figure 2). We expected epithelial ingrowth after trauma to the LASIK flap, but surprisingly this patient’s LASIK flap appeared completely intact and secure, with no flap edge lift or negative staining. Upon further questioning, the patient admitted that he noted slow vision decline even before the trauma. Therefore, it was unclear if the epithelial ingrowth was secondary to the tree branch injury or if it had been developing slowly even before the trauma and he became aware of the blurred vision only after the injury. Given that there were bilateral findings and that the patient sustained an injury to only his right eye, it was presumed that the patient likely had a slow and indolent epithelial ingrowth that began long before the trauma. At the initial evaluation in the cornea clinic, the patient was offered Nd:YAG treatment of the central and visually significant areas of epithelial ingrowth in his right eye. Topical prednisolone drops were discontinued at that time.
Discussion
Epithelial ingrowth describes the abnormal growth of corneal epithelium at the interface between the flap and the stromal bed following LASIK, deposited either at the time of the initial LASIK surgery or due to postoperative invasion of epithelial cells under the edge of the flap. It is not an uncommon complication of LASIK surgery, with incidence of visually significant epithelial ingrowth at 1% to 4% in primary cases and 10% to 20% in enhancement cases. The incidence may be less in femtosecond laser-assisted flap creation cases. Risk factors include any abnormality of the corneal epithelium such as anterior basement membrane dystrophy or recurrent erosion syndrome. Intraoperative epithelial defects, buttonholes and postoperative inflammation can also increase the risk. Flap relift with enhancement, which our patient underwent, has been shown to significantly increase the incidence of epithelial ingrowth.
The presentation can vary widely based on severity. Vision decline is a common complaint and can be due to either the opacities themselves or the induction of significant irregular astigmatism and refractive error. Other symptoms include glare and foreign body sensation from flap edge lift. The characteristic clinical finding is the presence of epithelial pearls or nests within the LASIK flap interface. Other findings include diffuse opaque epithelial ingrowth and/or a rolled-up flap edge with a thickened white-gray appearance. In severe cases, epithelial ingrowth can lead to flap melt, requiring amputation of the flap or keratoplasty. The Probst/Machat classification of epithelial ingrowth offers a guideline for grading and treatment. In general, epithelial ingrowth with aggressive growth in the visual axis will require more urgent treatment than thin growth at the periphery. Diagnosis is often based on clinical examination; however, AS-OCT may aid in the diagnosis by demonstrating hyperreflective opacities at the LASIK flap interface. Corneal tomography may also be useful in monitoring the severity and progression of epithelial ingrowth.
Most patients with peripheral epithelial ingrowth do not require surgical treatment as it is usually self-limited. However, Nd:YAG laser has been gaining popularity as a novel noninvasive method for treating epithelial ingrowth. First described in 2008, the Nd:YAG laser creates bubbles that, when focused at the epithelial ingrowth, can kill epithelial cells when set at an appropriate energy level (between 0.5 mJ to 0.8 mJ). It usually takes two to five treatments, but various case series have reported elimination of progression in all patients. Surgical flap lift with debridement is a more conventional treatment with variable rates of recurrence up to 36%. Due to this, various methods have been developed to facilitate a secure flap adhesion, including flap suturing, fibrin glue and ocular hydrogel sealants. Amniotic membrane grafting may also be utilized if there is evidence of flap injury or melting. Mitomycin C has been used on the scleral bed to decrease the chance of recurrent epithelial cell proliferation.
Our case is interesting in that the epithelial ingrowth occurred almost 20 years after LASIK surgery. It was unclear at the initial examination if this was secondary to the trauma. As the patient was complaining of vision decline before the injury, we presumed that the patient likely had epithelial ingrowth before the injury. This was further supported by the location of the ingrowth, which was central, without any evidence of ingrowth at the flap periphery. However, there have been several case reports demonstrating significant epithelial ingrowth induced by injury or trauma in the setting of LASIK. Such manifestations are likely due to the introduction of corneal epithelial cells into the LASIK flap interface.
Case continued
Three weeks after the initial exam, the patient returned for a scheduled Nd:YAG treatment. Upon examination, a dramatic increase of the central epithelial ingrowth in the right eye (Figure 3a) was noted despite no further vision decline. Laser treatment was deemed inadequate for the extent of the epithelial ingrowth, and the patient was scheduled for a surgical flap lift and debridement. Intraoperatively, two buttonholes were discovered in the LASIK flap following superficial keratectomy (Figure 3b), likely secondary to the stick injury. These were determined to be the point of entry for the epithelial ingrowth. The flap was lifted, debrided and sutured, and Tisseel fibrin sealant (Baxter) was used off label to cover the flap edges. A bandage contact lens was placed. At postoperative month 1, the patient was doing well without any evidence of epithelial ingrowth recurrence.
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- For more information:
- Yi Ling Dai, MD, and Naveen K. Rao, MD, can be reached at New England Eye Center, Tufts University School of Medicine, 800 Washington St., Box 450, Boston, MA 02111; website: www.neec.com.
- Edited by Allison V. Coombs, DO, MS, and Nisha S. Dhawlikar, MD, MPH. They can be reached at New England Eye Center, Tufts University School of Medicine, 800 Washington St., Box 450, Boston, MA 02111; website: www.neec.com.