Embryology- development abnormalities

Question 1

Congenital Cataract

Answer 1

Lens is white or opaque due to inadequate lens fibre growth
Caused by rubella infection in mothers and dominant gene inherited
Red reflex test- ophthalmoscope shown in both eyes in dark room- 24-48 hrs nhs
Treatment- inner ocular lens or contact lenses

Question 2

Congenital Glaucoma

Answer 2

Caused by high IOP like adults
Caused by abnormal development of iridocorneal angle structures and trabecular meshwork not developing properly , rubella in mothers
Shows by elevated IOP, abnormally deep anterior chamber, globe enlargement, corneal opacification
If untreated blindness will occur
If diagnosed within first year will respond well to treatment but may have reduced VA

Question 3

Coloboma

Answer 3

Occurs when choroid fissure in optic cup does not completely close in the 7th week.
Results in defect of inferior part of iris giving pupil a key hole appearance, may effect eyelids,cornea,lens,iris, ciliary body.
May effect retina which may compromise vision
<1 :10,000 births

Question 4

Aniridia

Answer 4

Bilateral condition where iris doesn’t develop- may be partially missing or entirely absent
Caused reduced VA, light sensitivity, hystagmus
Associated with glaucoma and cataracts
Mainly hereditary mutation/deletion of Pax 6 gene
No treatment but with opthalmic management and monitoring most retain useful vision.

Question 5

Anopthalmos

Micropthalmia

Answer 5

Absence of eye - sometimes due to gene absence of SOX2
Optic vesicle growth failure or lack of closure of neural tube

Micropthalmia- one or both eyes are abnormally small and have anatomic malformations
Due to alcohol abuse during gestation, infections herpes, rubella or genetics
May cause raised IOP,catarct, poor vision, in mild versions child is long sighted- hypermetropia
Patching may strengthen weaker eye

Question 6

Peters Anomaly

Answer 6

Rare form of anterior segment dysgenesis where abnormal cleavage of anterior chamber occurs.
Corneal development normally depends on neural crest migration which occurs in 3 distinctive waves- any disruption in this can lead to anterior segment dysgensis.
Affects any part of anterior chamber, iris etc
-Charcterised by a central corneal opacity translucency of central cornea
- Abnormal red reflex test
- management full thickness penetrating keratoplasty- corneal transplant
- iridoplasty - low energy laser burns to the peripheral iris to widen anterior chamber angle

Question 7

Albinism

Answer 7

Absent reduces tissue melanin- includes ocular melanin
presents with iris pigmentation, nystagmus (rhythmic, involuntary eye movements , photophobia( sensitivity to light), strabismus
No foveal pit due to lack pf pigment in RPE needed for macula development- main cause of poor vision
Management- limit to sun exposure due to risk of squamous cells
Strabismus may benefit from eye muscle surgery
Possibly new I-DOPA for ocular problems - dopamine is intermediate product in melanin synthesis