Glycerol: a much-appreciated medium

Case #1

It was a Wednesday about 2 weeks ago when a 71-year-old male presented to me complaining of decreased vision in the left eye for 1 month.  His wife stated he had suffered a “stroke” about 2 months earlier.  He then developed pain and blurred vision in the left eye. 

His chart stated his vision was “NLP,” or no light perception in that eye.  However, upon rechecking his visual acuity, I determined that he did have some light perception after all.  He was unable to close his left eye at all, and his left face drooped, confirming my suspicion of a 7^th nerve palsy.  A large, ~5x5 mm desmetocele flaunted itself prominently and precariously on the inferonasal cornea.  The anterior chamber was flat, and the iris was adherent to the cornea, making a nice solid seal to the then-perforation.  He also had a typical Zambian dense cataract.  

Although the eye was not leaking now, the extremely thinned protrusion in his cornea made me quite uncomfortable, so I decided to perform a tectonic corneal graft the very next day, utilizing glycerol-preserved corneal tissue provided by Global Sight Network, a humanitarian branch of the Alabama Eye Bank.  My tissue was from a 56-year-old who died in 2009 from anoxic brain injury; the glycerol preservation method gave it a shelf life of 5 years, making it suitable for urgent situations such as these. Ideally I would have wanted a slightly smaller graft, but I chose an 8.5 mm trephine...because that's the only size I have here in Africa.

The surgery was not like a straightforward PKP.  It was a combined procedure – much like I had grown accustomed to at Massachusetts Eye & Ear Infirmary – a corneal graft, sphincterectomy to open the tiny pupil, open sky extracapsular cataract extraction, intraocular lens placement, and temporary tarsorrhaphy.  

Postoperatively, his cornea was hazy (expected for this glycerol-preserved cornea), but his eye was intact and no longer at high risk for perforation.  At least upon checking him on postoperative day #1, he was already counting fingers at 1 foot. 

Case #2

A similar situation happened just 10 days before this in which a 61-year-old female presented with a horrible corneal ulcer with perforation, flat anterior chamber, and light perception vision.  The referring ophthalmologist had attempted to provide tectonic stability with a scleral patch graft and tarsorrhaphy but sent the patient to me when this did not provide an adequate solution.  

In order to stabilize the globe, I elected to perform a tectonic corneal transplant with the glycerol-preserved corneal tissue.  I emphasized that this was not for vision, but rather for stability of the globe.  Her iris was completely scarred to the cornea and cataractous lens, making it impossible to remove the cornea without also removing the iris and lens.  I elected to leave the patient aphakic, so after a limited anterior vitrectomy I simply sewed on the cornea.  This was my very first experience with the glycerol cornea.  It was much firmer, whiter, and more edematous than normal Optisol-preserved tissue.  After struggling with the initial suture and bending the first 10-0 nylon needle, I quickly learned how to handle this thicker donor tissue. 

By postoperative week #1, I was surprised to see that the cornea was clearing a bit.  I had a hazy view into the anterior chamber and surrounding structures.  The epithelial defect was closing in with a triangular shape centrally.  And the patient was counting fingers at 1 meter!  

Case #3

Exactly one week ago while I was in the operating theatre, a clinical officer (C.O.) popped his head into the room.  “Doc, there’s a corneal laceration that might need a patch graft or something.” 

“Can’t we just put a few sutures in?  Or does it really need a graft?” 

He hesitated, “Uh, there might be too much astigmatism with just sutures.”

“Bring him in, let’s take a look,” I replied. 

Sure enough, there was a crescent-shaped area of peripheral cornea inferotemporally with about 90% thinning.  Iris was right up to the wound.  The accident had occurred almost 1 week prior, so the perforation had sealed on its own.  But the area of corneal instability was too big for primary closure.  The C.O. was right. 

We talked about the various options.  A conjunctival advancement would afford no stability for this defect.  A scleral patch graft could work, but we’d have to painstakingly harvest it from the patient’s perfectly healthy scleral tissue.  In the end, I decided to perform a patch graft with a glycerol cornea.

I eyeballed the size of the defect.  It needed to be roughly crescent shaped, maybe 5 x 1.5 mm.  I asked the nurse for some heavy scissors to cut the tissue, which she didn’t have.  I opted for the #15 blade.  These versatile, disposable, razor-sharp blades cut precisely, but my only complaint was the resultant triangular edge rather than the smooth curved shape.  Nonetheless, it worked like a charm.  A crescent blade was then used to create an anterior lamellar dissection in my triangular/crescent shaped patch graft.  Nine 10-0 nylon interrupted sutures did the trick. Finally, a small paracentesis was placed, and LR effectively inflated the anterior chamber with no leakage from the wound.  Success.

Today the patient returned for his one week visit.  He was happy!  His vision after the accident was counting fingers, but one week after his graft his vision had returned to 6/18!  The epithelial defect in the graft has resolved, and all the sutures are intact.  We’ll have to remove these sutures in the future when things are better healed. 

These glycerol corneas are pretty amazing.  Their shelf life of 5 years makes them so easy to transport and store.  I have come to appreciate these tissues greatly in my first operative month in Zambia.  Thank goodness for glycerol.  And thank you, Global Sight Network!