Ophthalmology introduction

Question 1

What is the average axial length

Answer 1

23mm

Question 2

Differentiate myopia and hypermetropia

Answer 2

myopia ‘short sight’
long eyeball
image focuses in front of retina

hypermetropia ‘long sight’
short eyeball
image focuses behind retina

Question 3

What happens if there is misalignment of the visual axes

Answer 3

misalignment of the visual axes will lead to double vision or suppression of the 2nd image

Question 4

What is proptosis?

Answer 4

Inflammation (Graves ) in a bony box

Question 5

,…

Answer 5

….

Question 6

What occurs to the eye in orbital fracture

Answer 6

Orbital fracture= Box broken = enophthalmos & eye movement restriction (trapped inferior rectus)

Question 7

Outline the facial development

Answer 7

Branchial arches form in the 4th week
1st arch - forms the face
2nd- muscles of facial expression

Question 8

Outline the embryological development of the eye

Answer 8

• The eye begins to develop as a pair of optic vesicles on each side of the forebrain at the end of the 4th week of pregnancy.
• Optic vesicles are outgrowings of the brain which make contact with the surface ectoderm and this contact induces changes necessary for further development of the eye.
• Through a groove at the bottom of the optic vesicle known as choroid fissure the blood vessels enter the eye.
• Several layers such as the neural tube, neural crest, surface ectoderm, and mesoderm contribute to the development of the eye

Question 9

What is failure of fusion of the iris called

Answer 9

Iris coloboma, can also happen with retina (retinal coloboma)

Question 10

Visual milestones at birth, and 3 months

Answer 10

do not focus on targets further than 20-30 cm away

only see high contrast eg chequerboard not colours

cannot move their eyes between the two images

at 3 months should be able to
fix & follow

Question 11

Visual milestones at 5-8 months

Answer 11

good colour vision by five months of age

8 months old start crawling
reaches for objects

Question 12

Visual milestones at 9months-1year

Answer 12

visually spot a small (2-3 mm) object nearby

watches faces and tries to imitate expressions

searches for hidden objects after observing the “hiding”;

Question 13

By 2 years

Answer 13

By 2 years complete myelinization of the optic nerve is completed; acuity is normal

Question 14

By 2-5 yeats

Answer 14

2-5 years brain functions nearly adult basic sensory processing abilities. Analyzing complex visual scenes, specific objects and faces will occur later.

Question 15

By 3 years?

Answer 15

By 3 years: Retinal tissue is mature the child can complete a simple form board correctly (based on visual memory), do simple puzzles, draw a crude circle and put 2.5 cm pegs into holes.

Question 16

By 5-7 years

Answer 16

By 5-7 years: the functional development of brain substrates for perception of complex visual scenes takes still longer.

Question 17

Definition of blindness

Answer 17

Blindness is legally defined as ‘so blind that they cannot do any work for which eyesight is essential’.

Question 18

Most common cause of blindness globally

Answer 18

Cataract

Question 19

What is most common cause of irreversible blindness in working aged people

Answer 19

Diabetic retinopathy

Question 20

Outline the disease process in trachoma

Answer 20

There is infection with chlamydia trachomatis

This causes trachomatous inflammation and then scarring

There is then trachomatous trichiasis which causes the eyelashes to be pulled in

The lashes can scratch the corneal surface, leading directly or indirectly (from secondary infections) to corneal opacity

Question 21

What are the interventions for trachoma

Answer 21

Environmental improvements

Face washing

Abx treatment

Surgery for trichiasis

(at each stage, have a look)

or

SAFE:
Surgery, antibiotics, face washing and education & environmental improvements

Question 22

Abx treatment for trachoma

Answer 22

Tetracycline or azithromycin