This case is interesting because there are a lot of red herrings.

Last week, a 75 year old man came to me for his first ever eye test.  He had assumed the yearly diabetic retinal screening was a full eye test so had never been to an optician before.  During history and symptoms, he described sudden vision loss in his left eye six weeks ago* (this was what prompted him to see me).

Mr C realised he couldn’t see very well out of his left eye when he accidentally covered his right while he was watching TV.  What he then described sounded like a field defect.

Mr C is diabetic (type 2, well controlled) and was screened around 6 months ago.  There were no issues reported at the screening and he was kept on yearly recall.  He is also hypertensive but that, again, is under control.  His mum had glaucoma, which left her blind in one eye at a relatively young age.  He has a very high cyl in his left eye (+4.50DC) which has never been corrected.  He was hit in the left eye by a tree branch a few years ago and, although it was painful for a few days, he didn’t seek help.

So, we have a list of possibilities:

  1. retinal detachment
  2. glaucoma
  3. CRAO or CRVO
  4. maculopathy
  5. stroke
  6. other pathology
  7. combination/all of the above

His vision was R 6/9 and L 6/60, improving to R 6/6 L 6/36 when corrected.  He was tilting his head up and down when viewing the chart with his left eye, trying to find the best angle.

Pupils were fine – equal and reactive with no RAPD.

Mr C’s pressures were R 14mmHg and L 11mmHg.  A small difference between eyes, with the left pressure lower – something I’ve seen before with retinal detachments.  He did report seeing lots of floaters in the left eye recently.  There was no trauma (that he could remember), no flashing lights and the defect didn’t move.

The pressures were low enough to rule out acute closed angle glaucoma (and I confirmed his angles were wide open on van Herrick) so I dilated him and, while the drops were working, I did a supra threshold 24-2 fields test.  What I found looked like this:


That’s a definite inferior defect in the left eye and it respects the horizontal midline.  His fixation was very poor, though.  I tried to redo it but then we couldn’t get a threshold at all in the left eye as he couldn’t see the central spot without moving his eye around.

Finally, I asked him to sit at the slit lamp.

Starting at the front of the eye, there was an opaque area inferior to fixation that had some ghost vessels growing into it from the limbus, there was a cortical cataract inferior nasal and superior temporal.  Berger’s space was clear of tobacco dust.  There were lots of floaters and a Weiss ring in the vitreous.  The C:D ratio was 0.2 in both eyes, the NRR followed the ISNT rule and there was little to no cupping.  A quick glance at the fundus and nothing looked amiss.  There were no diabetic changes, the macula was flat and intact and the blood vessels looked okay.

Until that point, I was thinking it was a detachment so I was using my super field 90D and concentrating on seeing as much of the retina as possible.  When I couldn’t see any breaks or tears, I switched to my 78D lens and started looking really carefully at the macula and disc.

And there it was.  A little round white blob in one of the retinal arteries, just as it exited the cup.  It could be mistaken for a reflection from the artery wall or a little bit of myelin if you weren’t paying attention.  It was an embolism.

Now that I was really looking at the vessels, I could see that both the arteries and veins were thinner in the top portion of the retina when compared to the bottom**.  The fundus was still pink, though, and there was no cherry red spot at the macula.  It was a very subtle CRAO but it had a devastating effect on Mr C’s vision.

Our HES endeavours to see all CRAO patients on the same day so, when I called, they booked him into the afternoon clinic.  I sent Mr C away, letter in hand, and asked him to call and let me know how he got on.  Hopefully I’ll hear from him on Monday.


*Yes, six weeks. Not a typo.

** This was so much easier to spot on the fundus photo (which I wish I’d taken after the fields test rather than right at the end of the examination).