BLOG: When corneal hydrops call for surgical intervention
Corneal ectasia such as keratoconus, keratoglobus and pellucid marginal degeneration are not as rare as once believed thanks to improved imaging techniques, but complications such as hydrops remain fairly rare.
Hydrops affect as little as 2% to 3% of these patients, according to Barsam and colleagues.
With the advancement of corneal crosslinking (CXL), one can hope that the incidence of hydrops and even corneal transplant for corneal ectatic disease will greatly decrease in the future.
In fact, a Canadian study has already revealed that about half of keratoconus (KCN) cases required transplantation by 2016, just 6 years after the advent of CXL in that country (Sklar et al.). Norway noted a 50% decreased rate in penetrating keratoplasty (PK) to treat keratoconus 6 years after the introduction of CXL — although these data are likely skewed by the growing rate of deep anterior lamellar keratoplasty (DALK) being performed — and the Netherlands saw a 25% drop in the number of transplants needed for KCN after just 3 years (Sklar et al.).
But what about our patients who are past the help of CXL? What about our patients with already advanced ectasia suffering sequelae such as corneal scarring or hydrops?
Case report
I recently saw a 39-year-old Caucasian man with KCN who came in for a corneal transplant evaluation, only to have acute hydrops in the right eye on presentation. I immediately informed the patient that we would need to address this and then allow the inevitable scar to stabilize for several months before returning to any discussion about corneal transplantation. I educated him about hydrops, telling him that his cornea had thinned to the point that the inner corneal layers of Descemet’s and the endothelium had broken. With this split, the aqueous fluid inside his eye was rushing into his cornea causing stromal and epithelial edema, severe light sensitivity and poor vision while the inflammation later invited neovascularization of the cornea.
While ultimately self-limiting, this can take several months, and medical management is usually called for to reduce or limit fallout such as scarring, infection, neovascularization and even corneal perforation. We immediately started him on topical treatment that included Muro-128 (sodium chloride hypertonicity ophthalmic solution 5%, Bausch + Lomb), Cyclogyl (cyclopentolate hydrochloride ophthalmic solution 2%, Alcon), brimonidine, ofloxacin, prednisolone acetate and frequent preservative-free tears, only to have him worsen over the first few weeks. The cycloplegic was used to reduce photophobia and pain; the aqueous suppressant to lessen force on the posterior cornea; the antibiotic as prophylactic; hypertonic saline to reduce corneal edema; and steroid to reduce inflammation, subsequent neovascularization and scarring.
The patient’s cornea was too steep to consider therapeutic bandage contact lens placement.
A month from onset, his cornea had swollen to the point where we could no longer image with a Pentacam (Oculus) and had to measure pachymetry with a corneal OCT.
Throughout, the patient was incredibly symptomatic and asked me if there was anything else we could try. As a working father of three who felt unsafe to drive and too uncomfortable to view the computer screen that he needed to work, he needed some relief. It was time to think outside the box.
I am lucky to work with two amazing corneal specialists at our clinic. One of these colleagues had been reading the literature and offered an option: an anterior chamber air bubble paired with corneal Avastin injection (bevacizumab, Roche). The Avastin injection was used to regress corneal neovascularization that had developed during the acute phase of inflammation and help prevent further angiogenesis. After extensive education on possible intracameral injection risks such as cataract formation, pupil block, endothelial damage or infection, our patient could not have been more excited to proceed.
We’ve discussed air bubbles before with Descemet’s stripping automated endothelial keratoplasty and Descemet’s membrane endothelial keratoplasty corneal transplants. They’re used in a similar fashion here: to put pressure on the inner cornea. But instead of attempting to adhere an endothelial graft; for this patient the tamponade would act to close the tear in his Descemet’s layer and prevent further corneal edema. This technique is known to reduce healing time but is not expected to improve visual outcome and, therefore, might be considered controversial. However, the expedited healing is significant with air injected patients’ corneal edema resolving in 20 days on average rather than 64.7 days for control patients receiving conventional therapy. Those treated with air injection are also back into gas permeable contact lens wear quicker, an average of 33.4 days from hydrops onset vs. a whopping 128.9 days (Miyata et al). And when one considers that historically recalcitrant cases were treated with PK transplantation, this remains an important and less invasive option.
Understandably, with this intracameral gas injection technique it has been touted that earlier intervention means a quicker recovery, with best outcomes when performed in the first few days. But, again, my approach to practice is offering the most conservative solution where appropriate. I treated this patient for several weeks with conventional, topical therapy until he made no progress; only then did we consider more invasive treatment options. His successful outcome may be of greater interest because our patient did not receive surgical intervention until almost 7 weeks after hydrops onset and still benefited greatly from the procedure.
After a simple fill of the anterior chamber with air (surgical gases such as C3F8 or SF6 can also be used), the patient was left lying supine for a few hours. The surgeon then “burped” the air bubble to about half of the anterior chamber and let the patient go home. Much like an endothelial transplant postop, the patient was asked to lie flat on his back for about half of the next day.
At his 1-day postop, the patient could not have been happier. His vision went from count fingers at 1 foot to 20/200 in just a week, and his photophobia was now a minor complaint rather than a debilitating one. After 3 weeks he was seeing 20/60 without correction in the right eye. and his comfort was back to normal. His historical uncorrected visual acuity in the right eye was hand motion.
This case nicely demonstrates the corneal flattening that can occur after resolved hydrops. Despite a significant corneal scar, it is mostly off the visual axis, and his post-hydrops vision was much improved from before the event.
This patient now enjoys improved vision thanks to significantly flatter and (while still highly irregular) at least more regular corneal topography. We are currently monitoring the corneal scar for stability before sending him for a scleral fitting (he might enjoy greater contact lens tolerance now), or if adequate vision cannot be achieved, revisiting corneal transplant. If transplantation is called for, some surgeons may attempt a DALK, but with known scarring from a prior hydrops a full-thickness PK is most likely to be successful.
Be aware of referral options
As optometrists we are the first-line eye care providers for our patients, and like any health care profession a vital part of our job is knowing when to refer. To do this appropriately, we have to be aware of what options are available for our patients.
This patient suffered from a condition that we have all been taught can be helped along with therapeutics but will ultimately resolve on its own. However, no case is textbook, and this patient’s hydrops called for surgical intervention in the form of an intracameral air injection.
References:
- Barsam A, et al. Eye. 2015;doi:10.1016/S0161-6420(94)31110-9.
- Miyata K, et al. Am J Ophthalmol. 2002;doi:10.1097/ICO.0000000000002085.
- Sklar JC, et al. Cornea. 2019;doi:10.1097/ICO.0000000000002085.
Collapse