Eye Phase 3: the cornea

I've had two visits to the eye hospital within 7 days, not because there was anything untoward but because I had appointments with different specialisations. The first was the retinal clinic where I had various tests which showed that the swelling of the macula had 'dried out'; the oedema has gone. I don't notice much improvement because I can't see much anyway for a different reason: my compromised (it's called 'decompensated' in the jargon) cornea. So the macula appears to be normal again.

A week later, I went to see Mr Au who is the specialist in corneas and corneal transplants. The cornea is the 'front window of the eye'; the part that does most of the focusing of the image which it projects onto the retina. Mine is severely damaged from all the operations I've had and because of years of glaucoma. The endothelial cells on its inner surface, if damaged, cannot renew themselves but are vital as they pump water from the cornea. If this pump isn't working, the cornea becomes waterlogged causing the blurry vision - like looking through a ground-glass screen - that I have. The only cure is to replace the endothelial cells with a graft, a new and delicate operation called a DSEK or to replace the entire cornea (full-thickness keratopathy). In either case, the graft comes from a donor, someone who has died young and generously left their eyes to be used for helping the likes of me. I already have a piece of somebody else's eye in my eye, the result of the patch graft which Miss Fenerty placed over the tube and plate she inserted to control the glaucoma - which, I am happy to say over a year later, it does effectively. As a result of this anonymous post mortem generosity, I have registered as an organ donor; the least I could do.

I had only a short wait to see Mr Au himself. He is very brisk and efficient and pleasant with it. He did several tests on different machines to enable him to determine with precision what exactly would be the best option for my eye. For various compelling reasons to do with the geometry of my 'difficult' eye, the intra-ocular lens and pupil, he feels that the best course is for me to have a full thickness keratopathy. In this operation, he makes a circular cut - using an instrument like a cookie-cutter, though a little more refined - to actually bore out a hole in the front of my eye about 7mm in diameter. Into this, he inserts a donor 'button' - the replacement cornea - which he then sutures firmly into place using very fine radial stitches. The sutures remain in place for around 18 months and I will need steroid eye drops to prevent rejection. But the new cornea should mean that I can see clearly again. At present, the image quality is so poor that I get no image fusion, no stereoscopic vision, and can barely make out the biggest letter on the standard eye chart. If I don't have this graft, the outlook is worsening vision and pain associated with the oversaturated corneal tissue. I've already had a lot of pain with this cornea and I know how unpleasant it is. The operation is not without risk but the benefits are significant.

So the choice is easy! I'm on the waiting list for an operation in about 3 months.

Success, but what happens next?

In my latest trip to the Manchester hospital (phew, it's getting tiresome, all this travelling but at least most of it is on the train), I got to see Miss Fenerty, the senior consultant who has been so helpful to me and who has placed this drainage shunt implant in my eye. The pressure was a remarkable 10mmHg which is the lowest it's ever been since records began! It's the bottom end of the normal range now instead of way up above it. This means that the laser zapping last time to unblock the tube has worked. It also indicates fairly clearly that the pressure is properly controlled for the first time - and all without drugs. In fact in 3 weeks, I shall be completely off eye drops, the last one I'm using (an anti-inflammatory) being tailed off to zero over this period. Then I shall be drug-free for the first time since the glaucoma was originally diagnosed back in 1976. I took the opportunity to congratulate Miss Fenerty. I'm pleased to be off the drops not least because they may have affected my mental state, pushing me into depression, a known side-effect of some of them. I will now find out if this theory is correct.



But what now? At present, the vision remains very poor and I have double images too. What can be done about it? There are several options and another specialist, Mr Ho (I think), joined us to discuss what to do. Or rather, they discussed and I listened mostly. Mr Ho specialises in corneal transplants (see figure) and I shall probably need one soon. The inner lining of my cornea - called the epithelium - is damaged. This means it can't pump water out of the cornea into the anterior chamber of the eye from which it would drain through the tube. So the cornea is waterlogged which gives me vision like looking through a fog. The damage has been due to the glaucoma and also because of the intra-ocular lens implant I had done about 12 years ago which has become loose and has moved and is physically damaging the epithelium. The epithelial cells cannot regenerate themselves when they are compromised in this way. (The cornea is said to be 'decompensated'.) Hence the probably need for a donor cornea some time in the near future.



The issue is the lens, known as the ACIOL (Anterior Chamber Intra-Ocular Lens). This needs to be removed soon and replaced, but by what? Because my iris was partly removed in the original cataract operation back in 1972, there are no proper anchorage points for a lens - which is why there's trouble with the one in there now. Further damage has been done by the 10 subsequent operations. So how do they fit a new lens and anchor it? There are various possibilities, none sounding ideal, but Miss Fenerty is arranging for me to see a lens specialist at the hospital so he can take a look and see what would be the best option. The results of that consultation will be my next post in a few weeks time.