64. Refractive Eye Problems

Question 1

Define the following:
Ametropia
Myopia
Hyperopia
Astigmatism
Presbyopia
Amblyopia

What is the synkinetic reflex?

Answer 1

Ametropia: light doesn’t focus on retina
Myopia: light focuses in front of retina (eye too long) - NEAR SIGHTED
Hyperopia: light focuses behind retina (eye too short) - FAR SIGHTED
Astigmatism: light from different angles focuses to different distances - EGG SHAPE
Presbyopia: reduced accommodation, occurs with advancing age
Amblyopia: blurred vision due to failure of visual pathways to fully develop (before 9yrs old - no clear image to retina or eyes maligned)
Synkinetic Reflex: convergence = miosis (constriction) = accommodation

Question 2

For Myopia, Hyperopia, and Astigmatism:

What is their axial length, corneal contour, lens contents, accommodation abilities that would explain the abnormality?

Answer 2

Myopia

• long length
• steep cornea
• nuclear cataract (cloudy lens)
• spasm of accommodation

Hyperopia

• short length
• flat cornea
• aphakia (loss of natural lens)

Astigmatism

• variable lens
• mixed corneal contour

Question 3

What are the ways of correcting refractive error? (Natural way and 5 tx)

Answer 3

Accommodation - natural tx for hyperopia (but synkinetic reflex causes convergens/miosis)

1. Glasses - converging/diverging lens
2. Contacts - correct ametropia and create new smooth corneal surface
3. Corneal Refractive Surgery: laser/incisional/transplant - remove abnormal shape and sharpen tissue
4. Phakic Lens implant - insert lens on top of bio lens under iris
5. Lensectomy with IOL insertion - lens exchange - can correct near/far vision and astigmatism