Posteior Subcapsular Cataract

Question 1

When lens fibres are formed, in psc they take a different approach, explain the approach?

Answer 1

The cells migrate towards the posterior pole where they become vacuole shaped and form a thin opaque layer between the posterior capsule and the lens fibres that terminate at the posterior sutures

Question 2

Describe a psc opacity:

Answer 2

It’s a round region at the posterior pole

Question 3

Are psc identical in all px’s?

Answer 3

No, the shape and size varies between individuals

Question 4

Why is inspection of psc difficult with a non dilated pupil?

Answer 4

Because without a dilated pupil it’s hard to see the size and shape beyond where the undilated pupil margin also the angle between the observation and the illumination would need to be very narrow which increases corneal reflections

Question 5

What is the best method to assess a psc?

Answer 5

Retroillumination in a dark room is useful because of the partial dilation and the opacities being viewed in silhouette

Question 6

In psc what factors cause the sx to vary between px’s?

Answer 6

The size,shape, density and the proximity to the visual axis

Question 7

Describe the sx for psc?

Answer 7

• blur (Abb/scatter)

- glare (opacity induced scatter)

Question 8

What influences the symptoms of psc?

Answer 8

• pupil size: brighter the light, the greater the miosis and the greater the influence of psc on light entering
• the degree of miosis: sx at near are greater than at distance due to miosis preventing the opacity to bypass light entering
• night vision is best because the pupil is dilated

Question 9

If you have a dense psc or if the psc is closer to the visual axis, what do you expect of the contrast?

Answer 9

With dense psc/close to visual axis light scatter is maximal therefore veiling luminance will also be maximal therefore psc opacities will have a disproportionate effect on contrast sensitivity (some report a reduction in CS)

Question 10

What should you do if you have a px who’s va is affected by light scatter?

Answer 10

Explain glare sx and what situations will make the glare worse eh (when the pupil constricts)

Question 11

Because it’s hard to detect psc immediately, what else can the optom do to ensure a psc isn’t missed?

Answer 11

He can explore sx in detail especially when they complain of glare rather than blur

Question 12

If you suspect a px has psc, what tests can you do?

Answer 12

Pelli robson to check CS or dilate the pupil to have a look