Monday, April 1, 2013

Up to my eyeballs...

Warning: Graphic content ahead!

As part of her biology practicals, Lesley-Anne  had to dissect an eyeball to examine the different parts. The students were told to buy a mammal's eye because it's closest in structure to the human eye.  Most kids came with pig's eyes.

First, they cut away the muscles and fats surrounding eye, making sure not to sever the optic nerve.  Among the muscle, there should be a rigid portion which is eyelid.  According to Lesley-Anne, what's gross is that some of the eyeballs still had eyelashes still attached to them, so you can't really escape the notion that it's a real eye.

Once the eyeball is clean, they take a scalpel and carefully scrape at the side of black portion until the thick transparent layer (cornea) has a small hole.  Then they gently squeeze the eye until a blackish liquid emerges.

When the liquid is removed, a pair of small scissors is inserted into the hole to widen it.  That's when they have to squeeze very hard to remove a glob of white gel (vitreous humour).  This is what keeps your eye shape.  What also comes out is the lens which is a hard, transparent ball that looks like a glass bead.

With the inside of eye now empty, they must cut a sample of cornea and then make 2 incisions on side of eye.  It can then be turned inside out for the students to see inside of eyeball.  The inside surface is black and looks like it's stained with ink.  Amidst the black, there is a white spot that is linked to the optic nerve - that is the blind spot.  Near the incision, there is a portion of the inner surface that is black but streaked with whitish lines. This is the iris, the lines are radial muscles that control pupil dilation.

You paste the different parts on a labelled grid and as Lesley-Anne says, then you wash your hands a lot.  LOL.

This is a photo of the eyeballs prior to dissection, taken by her friend.

Last year, Lesley-Anne had to dissect a pig's heart.  She says the heart isn't as disgusting cos can psych yourself into thinking you're just handling a piece of meat. The eyeball, on the other hand, seems to follow you.  Even as she was relating the process of dissection, I felt squeamish and Andre kept saying "ewwwwww!!" as he covered his eyes as if protecting them.

On the other hand, at least an eyeball has no blood.  For the heart, the students had to spend a lot of time washing the blood clots out of it.  Anyway, Lesley-Anne says she'll much rather dissect an eyeball than a cockroach.  I totally agree.

1 comment:

Anonymous said...

grotesque! i get nightmares looking at it

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