Optic Neuropathies

Question 1

Does optic nerve belong to CNS or PNS?

Answer 1

CNS

Question 2

Where does myelination of optic nerve normally happen?

Answer 2

Post lamina cribrosa

Question 3

Congential optic neuropathies

Answer 3

Size, orientation, drusen, closure defects, vascular abnormalities

Question 4

Involutional ON

Answer 4

Mitochondrial

Vascular collapse

Question 5

Sutrcture/mechanical ON

Answer 5

Due to truama

Intracranial HTN

Question 6

Circulatory ON

Answer 6

• ischemic optic neuropathy: NAION, AION, DION

- stagnant hypoxia: CRAO

Question 7

Infections/inflammatory ON

Answer 7

Infection
AI
Demyelination disease

Question 8

Congential hypoplasia of the ONH profile

Answer 8

Most common congential defect

Assocaited with a Tehran alcohols use, infection ,drug use, diabetes, pituitary and intracranial abnormalities

Question 9

Pathophysiology of congential ONH hypoplasia

Answer 9

• primary failure of the retinal ganglion cells
• DM/DD ratio >3.2 (normal 2.1-3.2)
• mutations on some genres

Question 10

DM/DD ratio

Answer 10

DM-distance from macula to temporal edge of ONH

DD: disc diameter

Ratio of the disc diameter to the distance from the center o the macula to the temporal edge of the disc

Question 11

Presentation of congential hypoplasia of ONH

Answer 11

• reduced VA, etc

- double ring sign: due to glial replacement tissue filling the gap between the scleral opening and the small nerve

Question 12

Superior segmental optic nerve hypoplasa

Answer 12

Causes inferior VF defect

- sometimes hard to see

Question 13

Septo-optic dysplasia (de Morsier sybdrome)-congential ONH hypoplasia

Answer 13

Midline dysgenic resulting in loss of septum pellucidum, pituitary abnormalities, optic disc hypoplasia
-isolated venous toruosity (no DM or microvascular disease to cause it)

Question 14

Megalopapilla-congenital neuropathies

Answer 14

• excess of non-neural glial tissue beceoms invaginated into the optic cup during development
• large scleral foramen

Question 15

Megalopapilla presnetaionts

Answer 15

• the disc may appear to have a large CD ratio

- DM/DD ratio is less than 2

Question 16

Myelination at optic disc-congenital neuropathies

Answer 16

The oligodendrolglia myelinate the optic nerve a process which usually ends at the lamina cribrosa but occasiaonly extends into the visual retina. There maybe an unmyelinated area between the disc and the myelinated fibers
-VF depression

Question 17

Disc drusen-congential neuropathies

Answer 17

• usually not clinically apparent until early adulthood
• usually bialteral
• small scleral opening is the primary cause. Nerves become crowded when passing through. The metabolic activities get affected and there will impaired axonal transport
• disc drusen are the result of axoplasmic derivatives from disintegrating nerve fibers. Extruded mitochondria and debris are prone to calcification

Question 18

Fundus exam of disc drusen

Answer 18

• elevated disc
• deflection of the vessels
• the NFL is not edemtaous and the vessels do not show the degree of congestion and stasis that would be expected with true edema
• the ILM is wrinkled due to the stretch effect assocaited with the elevation of the disc

Question 19

Typical appearance for disc drusen

Answer 19

Lumpy bumpy

Question 20

Progression of disc drusen

Answer 20

• visible disc drusen are rare in children. Most cases present with elevated discs and buried disc drusen
• there is not a consistent relationship between the VF defect and the location of visible drusen

Question 21

Disc drusen complications

Answer 21

Peripapillary hemorrhages which may extend towards the macula

In severe cases, arterial and venous shunts form and to the choroidal circulation may develop

Question 22

Diagnosis of disc drusen

Answer 22

B scan echography most reliable

Question 23

VF defect and disc drusen

Answer 23

Disc drusen May present with a variety of VF defects

Question 24

Managment of disc drusen

Answer 24

• if no VF defect: yearly routine exams including IOP and VF screening
• if VF defect, then serial IOP, VF, OCT every 6 months
• if IOP is borderline, or progressively VF defect, then consider ocular antohypertensive therapy
• treat paeripapillaryu CNVM if it occurs

Question 25

Incompletely closure of the optic disc

Answer 25

Cavitary sybdrome

• Coloboma
• Morning glory
• Optic pit

Question 26

Misaligned closure of the ONH

Answer 26

Tilted disc syndrome

Optic pit

Question 27

Cavitary syndrome: coloboma

Answer 27

Incomplete closure of the optic cup

-usually inferiorly

Question 28

Presentation of coloboma ONH

Answer 28

• poor VA
• unilateral or bilateral
• double disc appearance
• often associate with staphyloma
• maculoschisis, serous macular detachment, peripheral retinal detachment

Question 29

Morning glory disc

Answer 29

• more common in females
• unilateral more often
• associated with craniofacial disorders, pituitary defects, cerebrovacualr abnoraliesi
• variant of coloboma
• often asymptomatic: 25-75% risk fo serous macula detachment

Question 30

MGD compared to Coloboma

Answer 30

• less assocaited with systemic problems
• more common in females and more common in whites
• characterized by a funnel appearance and abnormally straightened vessels

Question 31

Intracranial abnormalities in morning glory disc

Answer 31

Problems with cerebral arteries

Question 32

Optic pits

Answer 32

• focal defects at level of lamina cribrosa

- variant of coloboma

Question 33

Presentation of optic pits

Answer 33

Visual acuity is typically normal
Serous macular detachments and/or maculoschisis occur in 30-50% of pits most often between ages 20-40
-mostly inferiortemproal with hyper pigmentation adjacent to the pit

Question 34

Tilted disc

Answer 34

• also-aligned closure of the embryonic optic fetal fissure
• abnormal axial length
• sometimes associated with astigmatism, vascular abnormalities
• complications are serous macular detachment and CNVM