Name the bones that form the medial wall of orbit. Contents of orbit.

Bones that form Medial wall of orbit:

  1. Frontal process of maxilla
  2. Lacrimal bone
  3. Orbital plate of ethmoid
  4. Body of sphenoid.

Contents of orbit:

  1. Eyeball

  2. Fascia: Orbital and bulbar

  3. Muscles: Extraocular muscles

    • 4 recti
    • 2 oblique
    • LPS

       4.Vessels:

  1. Ophthalmic artery
  2. Superior & inferior ophthalmic veins
  3. Lymphatics

     5.Nerves:

  1. Optic
  2. Oculomotor
  3. Trochlear
  4. Abducent
  5. Branches of ophthalmic nerve
  6. Parasympathetic nerves

     6. Lacrimal gland & Lacrimal sac

     7. Orbital fat.

[Ref: Basak/4th/20]

How visual field can be measured?

Measurement of Visual field:

Visual field can be measured by Perimetry.

Methods of Perimetry:

A.     Kinetic methods:(to see peripheral field)

    • Confrontation technique
    • Tangent screen (to see central field) / Bjerrum target screen
    • Lister’s perimeter
    • Goldman’s perimeter
    • Aimark’s perimeter
    • Camphimeter

Static methods: Computed visual field analyzer (to see both central and peripheral field)

  • Humphrey perimeter
  • Octopus perimeter
  • Henson perimeter
  • Fieldmaster perimeter
  • Ocuplot perimeter

Advantages of pseudophakia over aphakia.What is pseudophakia & aphakia?

Advantages of pseudophakia over aphakia/ over spectacle correction:

1)      Rapid improvement of quality & quantity of vision in IOL implantation.

2)      No spherical aberration & prismatic effect in IOL.

3)      IOL is cosmetically well accepted.

4)      Image magnification in IOL is only 0-2%

5)      No alteration of visual field in IOL.

6)      Binocular vision is possible.

[Extra answer:

Aphakia:

Optically, aphakia means absence of the crystalline lens from its normal anatomical position in the pupillary area. {Literally, aphakia means absence of the crystalline lens from the eyeball}

Pseudophakia/Atriphakia:

Pseudophakia means replacement of human opaque lens by artificial transparent intr-ocular lens. ]

What are the parts of an Intra ocular lens? What are the materials they are made of?

Parts of intra ocular lens(Artificial lens):

1)      Optic part

2)      Two plastic haptics (that are shaped like curved wires)

Materials IOLs are made of

1)      Polymethylmethacrylate (PMMA) was the first material to be used successfully in intraocular lenses.

2)      Advances in technology have brought about the use of silicone and acrylic, both of which are soft foldable inert materials.

[Ref:wiki]

What is ciliary body? Functions of ciliary body.

Ciliary body:

It is the middle part of the uveal tract, which is directly continuous with the choroid behind and with the iris in front.

Functions of ciliary body:

1)      Suspension of lens.

2)      Accommodation.

3)      Secretion of acqeous humour (by non-pigmented cells)

4)      Secretion of some of the glycosaminoglycans of the vitreous body.

[Extra answer: Uveal tract: It is the middle vascular coat of the eyeball, which consists of the choroid, ciliary body and iris, forming a continuous structure]

[Ref: Gray’s Anatomy/38th/1326-1331]

What is optic Atrophy? What are the types of optic Atrophy?

Optic atrophy:

Optic atrophy is the degeneration of optic nerve fibres with loss of their myelin sheaths and characterized by the pallor of the optic disc.

Types of optic atrophy/ Classification of optic atrophy:

  1. Aetiological classification:

1)      Primary

2)      Secondary

3)      Consecutive

  1. Anatomical Classification:

1)      Ascending optic atrophy

2)      Descending optic atrophy

What is optic atrophy, optic neuritis?

Optic atrophy:

Optic atrophy is the degeneration of optic nerve fibres with loss of their myelin sheaths and characterized by the pallor of the optic disc.

Optic neuritis:

Optic neuritis is an inflammation or demyelinating disorder of the optic nerve.

[Ref: Basak/4th/340]

Classification of optic neuritis:

1)      Papillitis

2)      Neuroretinitis

3)      Retrobulbar neuritis

What are the parts of optic nerve? Function optic nerve.

Parts of Optic nerve:       

1)      Intraocular – 1 mm

2)      Intraorbital – 24 mm

3)      Intracanalicular – 9 mm

4)      Intracranial – 16 mm

 

Total length 5.0 cm/ 50 mm

 

[Ref: Basak:4th/333]

Function of optic nerve:

            It transmits visual impulse from retina to the visual cortex.

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