Lens

Question 1

Causes of subluxed lens

Answer 1

HHEWASM (bad acryonym, i know :-(

Homocystinuria - down and in.  MR.
Hyperlysinemia
Ehlers Danlos
Ectopia lentis +/- et pupilae
Weil Marchesani
Aniridia
Sulfite oxidase deficiency
Marfans - up and out

Question 2

Microspherophakia - ddx and how to treat

Answer 2

*Weil marchesani
Peters
Marfans
Alports

May cause ACG by the lens pushing forward on the pupil margin. Rx by dilating - pull the zonules, flatten the lens and pull it back

Question 3

Generations of IOL formulas and how they differ

Answer 3

ACD = anterior chamber depth

1 - ACD constant (SRK)
2 - ACD related to AL
3 - ACD related to AL & K (Holliday 1, Hoffer, SRK-T)
4 - complex formula (Holliday 2)

Question 4

Which IOL formulas are best for short, med, long eyes

Answer 4

Short - Hoffer Q, Holladay 2
Med - Holladay 1, SRK-T, Hoffer-Q, Haigis
Long - Holladay 2, SRK-T, Haigis

Question 5

4 ways of calculating IOL after LASIK

Answer 5

1. Historical K
2. Using RGP CL
4. Online calculators

Question 6

Types of hyperopia

Answer 6

Absolute = absolute minimum they need to see at distance
Manifest = most plus you can push on them during manifest refraction
Cycloplegic

Latent is the different between manifest and cycloplegic

Question 7

ASC is caused by? (histo description)

Answer 7

Secreted by irritated metaplastic anterior epithelial cells

Question 8

PSC is caused by? (histo description)

Answer 8

Bladder cells adjacent to lens capsule

Question 9

Retained lens nuclei in what conditions

Answer 9

Trisomy 13
Rubella
Lowe’s

Question 10

Silicone oil causes what types of refractive changes

Answer 10

Measurement of AL: SO slows down the wave so the eye looks longer than it is.

After you correct for the AL, add 3D to the lens power (expect the SO to cause a hyperopic shift).

If already have IOL in place, causes hyperopic shift

Question 11

Types of biometry

Answer 11

Optical (IOL master) > immersion > contact