0:00

This was a case that was sent in with

0:03

visual disturbance on the left side.

0:06

As we scroll through this case,

0:08

we note the discrepancy in the size of the

0:11

globes between the left and the right,

0:14

in that the left globe is much larger than the right.

0:18

So, we have a case of microphthalmia.

0:22

As far as the etiology of this,

0:25

one would look at the thickness of the ocular

0:30

membranes between the normal right globe

0:36

versus the left globe.

0:38

And what one sees is that more posteriorly,

0:42

there is thinning of the ocular membranes.

0:48

This is also protruding slightly

0:53

along the temporal aspect of the orbit.

0:58

So we have an enlarged globe,

1:01

we have thinning of the ocular membranes.

1:04

We would call this uveoscleral thinning, and we have some

1:08

protrusion laterally with respect to the optic nerve.

1:13

This is an entity which is known as a staphyloma.

1:18

It has nothing to do with staph aureus

1:20

or staph epidermidis infection.

1:23

It is a term which is used for an elongated

1:27

globe that has the uveoscleral thinning.

1:37

The most common cause of axial staphyloma, that is

1:42

enlargement in the anterior to posterior direction,

1:46

is from axial myopia, which is short-sightedness.

1:52

However,

1:53

there are other etiologies for staphyloma,

1:57

post-infectious etiologies,

1:59

particularly in those patients who have

2:01

chorioretinitis or after trauma.

2:06

So this may be a complication of a traumatic injury to

2:09

the globe. It may occur due to nearsightedness,

2:14

or it may be due to an infection.

2:18

The most common of the chorioretinitis categories

2:22

of disease is from CMV, cytomegalovirus.

2:27

And CMV is a known pathogen that occurs

2:33

most commonly in patients with AIDS

2:35

and accounts for the majority

2:38

of the post-infectious staphylomas.

2:42

You can see that thinning

2:46

on both sides of the optic nerve,

2:48

but the protrusion of a staphyloma generally

2:50

is towards the temporal side of the globe.

2:56

Sometimes a staphyloma must be distinguished

3:00

from a coloboma.

3:02

A coloboma is a congenital abnormality, which also occurs

3:08

with elongation of the globe and misshapen globe.

3:13

the most common form of a coloboma is a protrusion

3:18

which occurs into the optic nerve head.

3:24

So the protrusion,

3:25

as opposed to being temporally located

3:28

with most of our staphylomas,

3:30

will occur into the optic nerve head itself in the

3:34

congenital coloboma. And this is the differential diagnosis.