DEVELOPMENT OF THE EYE MILESTONES

Embryonic and fetal period

Stage of growth   ::   Development

2.6 mm (3 weeks)           Optic pits appear on either side of cephalic end of forebrain.

3.5 mm (4 weeks)           Primary optic vesicleinvaginates.

5.5 to 6 mm
                    Development of embryonic fissure

10 mm (6 weeks)            Retinal layers differentiate,lens vesicle formed.

20 mm (9 weeks)            Sclera, cornea and extra ocular muscles different-tiate.

25 mm (10 weeks)           Lumen of optic nerve obliterated.

50 mm (3 months)          Optic tracts completed, pars ciliaris retina grows forwards, pars iridica  retina grows forward.

60 mm (4 months)          Hyaloid vessels atrophy, iris sphincter is formed.

230-265 mm                  Fetal nucleus of lens is complete,
(8th month)                   all layers of retina nearly developed, macula starts differentiation.

265-300mm                   Except macula, retina is fully
(9th month)                   developed, infantile nucleus of lens begins to appear,pupillary              membr-ane and  hyaloid vessels disappear.

Eye at birth

• Anteroposterior diameter of the eyeball is about
  16.5 mm (70% of adult size which is attained by
  7-8 years).
• Corneal diameter is about 10 mm. Adult size
  (11.7 mm) is attained by 2 years of age.
• Anterior chamber is shallow and angle is narrow.
• Lens is spherical at birth. Infantile nucleus is
  present.
• Retina. Apart from macular area the retina is fully
  differentiated. Macula differentiates 4-6 months
  after birth.
• Myelination of optic nerve fibres has reached
  the lamina cribrosa.
• Newborn is usually hypermetropic by +2 to +3 D.
• Orbit is more divergent (50°) as compared to
  adult (45°).
• Lacrimal gland is still underdeveloped and tears
  are not secreted.

Postnatal period

• Fixation starts developing in first month and is
  completed in 6 months.
• Macula is fully developed by 4-6 months.
• Fusional reflexes, stereopsis and accommodation
  is well developed by 4-6 months.
• Cornea attains normal adult diameter by 2 years
  of age. 
• Lens grows throughout life.