Pediatric Optometry: L2: Vision Development Flashcards
1
Q
Development of Vision
- Purpose is to Build what?
- Also needs to Build what System?
* She will NOT ask specific Days on the Exam. Learn them regardless for Boards, but just know that if something happens in a certain time period, what abnormalities will we expect…
A
- TRANSPARENT OPTICAL SYSTEM (forming a continually focused image of the external world)
- NEURAL SYSTEM (transmit information reliably yet recalibrate constantly as a child grows)
2
Q
Optical Components
- What 5 structures are important?
A
- Cornea
- Lens
- Aqueous
- Vitreous
- Pupil
3
Q
Embryonic Period
- Time period of Gestation?
- Abnormal events result in what?
a. What 2 major events? - First evidence of Eyes seen in how many days/weeks?
- Neural Tube completed in how many days?
a. Optic Vesicle?
b. What else is formed?
A
- First 2 months
- Major Structural Malformations
a. Infection and Trauma - 22 days or 3 wks
- 24 days
a. Day 25
b. Optic Stalk/Nerve Formation
4
Q
Fetal Period
- Time?
- Development of what?
- Disruption during this period does what?
A
- 9 wks to BIRTH
- Function of tissues
- Abnormalities of function
5
Q
Development of the Lens
- Develops from what?
a. Fully developed on what day? - What day is the Lens Placode derived from SURFACE ECTODERM?
a. If separation fails or is incomplete, it’s called what?
A
- Optic Vesicle
a. Day 25 - Day 27
a. PETER’s ANOMALY
6
Q
Peters Anomaly
- Lens is Adherent to what?
a. What defect occurs? - Central Corneal Opacity is what?
- Usually U/L or B/L?
A
- To Cornea
a. There’s a POSTERIOR CORNEAL DEFECT w/Termination of DESCEMET’s MEMBRANE where the lens is adherent to the CORNEA. - LEUKOMA (Lens stalk and “top hat” lens shape may be present)
- Typically U/L
7
Q
Development of the Lens
- Formation of what?
- Hollow vesicle lined with what cells?
- What do the Posterior Cells do?
- Up to 8 Wks of Gestation, the Lens is longer in which direction?
- When the child is born, what shape is the lens?
- The Adult Lens is longer where?
A
- of Lens Vesicle
- Epithelial Cells
- Elongate forming Fibers
- Lens longer ANTERIOR/POSTERIOR
- Spherical at BIRTH
- Longer PARALLEL to the IRIS PLANE
8
Q
Corneal Development
- Starts to develop at how many weeks?
a. How?
b. 3 Waves of Limbal Migration occur from NEURAL CREST TISSUE: What 3 things? (KNOW!) - End of 3rd Month
a. What cell layer is Adult like?
b. First evidence of what Corneal Layer? - 4th Month
a. What layer is the only layer missing?
b. When does it appear?
A
- 6 weeks
a. Epithelium Separates from Lens Vesicle
b. Enodthelium; Corneal Stroma; Iris Stroma
- a. Endothelium
b. of Descemet’s Membrane - a. Bowman’s Layer
b. 5th Month
9
Q
Cornea
- Horizontal Diameter
a. Birth
b. 1 Year? - Vertical Diameter
a. Birth? - Surface Area
a. Birth
b. 20 Months - Keratometry
a. Birth
b. 6 Months - Thickness
a. Birth
b. 6 Months
A
- a. 9-10.5 mm
b. 11-12 mm - a. 10.4 mm
- a. 102 mm^2
b. 130 mm^2 - a. 51.3 D
b. 45.2 D - a. 0.96 mm
b. 0.52 mm
10
Q
Development of Vitreous **If this doesn’t form properly, there can be some serious problems!
- 3 Stages
a. Primary Vitreous
b. Secondary Vitreous
c. Tertiary Vitreous - PPHV (Persistent Hyperplastic Primary Vitreous)
a. What is it?
b. What can it result into?
c. What can happen if the Primary VITREOUS FAILS to FORM? (4)
A
- a. 5th-6th wk
b. 6th wk to end of 3rd month
c. >12 wks - a. Hyaloid vascular system not completely regressed at birth
b. Mittendorf Dot
c. Microphthalmia; Shallow AC (Risk of Glaucoma); Lens opacities; Leukocoria or RD
11
Q
Sclera
- Sclera develops from what structure?
- Migrates b/w Axons to form what?
- Scleral Fibers thicken over time: So Infant Sclera is what?
- Easily Collapsible: so what can we NOT do until a child is over 2?
A
- from OPTIC NERVE
- LAMINA CRIBROSA
- It’s thinner and more Elastic
- IOL Placement
12
Q
Conjunctiva
- Growth of Conjunctival Fornix Mirrors Development of what?
- Sterile when?
- Bacterial Flora is adult like by when?
- Why are babies given Prophylactic Erythromycin or Silver Nitrate?
A
- of Palpebral Fissures
- at BIRTH!
- w/in 5 DAYS!
- Neonatal Opthalmia (N. Gonorrhoeae, and Chlamydia Trachomatis)
13
Q
Iris Development
- Develops from what?
a. At what Week? - Stroma is derived from what cells?
- Dilator/Sphincter and Pigment Epithelium are derived from what?
- By Wk 12, Starting to form what?
A
- Outer Pigmented Layer of the Optic Cup
a. Week 8 - Neural Crest Cells
- Neuroectoderm
- the Edge of the pupil
14
Q
Aniridia
- What exists, but all structures from neuroectoderm are absent?
- Associations? (3)
- Hereditary?
- Counsel on what?
A
- Iris Stroma Exists
- Glaucoma, Nystagmus, Low Vision
- Familial
- Sun Protection!
15
Q
Iris Development
- Unknown Eye color until what age?
a. Why? - Pupillary Aperture is what at first?
- Anisocoria of up to how much is NORMAL in 9% of INFANTS?
- Pupillary response to light is present if Gestational Age is > than how many weeks?
A
- 1-2 years
a. Due to increased pigmentation in Iris Stroma - 1.8mm -5.4 mm initially
- up to 1 mm
- > 31 WEEKS!