THE VITREOUS

Abdelmonem Hamed, M.D.Professor of OphthalmologyBenha College of MedicineFellow of Baylor College of Medicine, USA

The vitreous is an inert, avascular, transparent,

jelly – like structure which serves only optical functions.

It consists of a delicate framework of collagen and hyaluronic acid.

Wight: 4gmVolume: 4ml

Attachments: It is attached

anteriorly to the lens and ciliary epithelium.

It is known as the "vitreous base".

Attachments: It is attached posteriorly to the edge

of the optic disc and macula lutea.

Function: The vitreous forms one of the

refractive media of the eye. (RI 1.33)

RI of H2o = 1.369 RI of air = 1 .00 RI=Measure of the

refraction of a beam of light on entering a denser medium Nutrition :

It derives nutrition from the surrounding structures like choroids, ciliary body.

OPACITIES IN THE VITROUS

Etiology: Development causes: The

opacities are usually located in the Cloquet's canal.

Degenerative causes.

OPACITIES IN THE VITROUS

Vitreous: is optically clear

structure Pseudo membranes

and pseudo fibers appearing as moving folds (Vit. floaters, or Muscae volitantes)

Weiss’ ring

Asteroid hyalosis:

Spherical, white bodies of calcium soaps resembling snowball.

It is asymptomatic therefore no treatment is required.

A pars plana vitrectomy may be considered if vision is markedly reduced.

Synchysis scintillans:

deposition of highly refractive cholesterol crystals in the vitreous.

Golden shower is seen during the movements of the eye.

No treatment is indicated.

Other causes of vit. opacities: High myopia. Retrolental fibroplasia. Wagner's disease. Ehlers- Danlos syndrome Marfan's syndrome Chronic cyclitis. Diabetes and Eale's disease Neoplasm. Amyliodosis

Q: Can vitreous

degeneration be treated?A: Molecular bonds of the clear vitreous cannot be restored after vitreous

collapse = no medical ttt

VITAMINS

Antioxidants may retard the denaturation of protein

Treatment of vitreous opacitiec1. YAG laser2. Vitrectomy

NEODYMIUM-YAG LASER infrared spectrum focused beam energy 4 - 6 milli

joules 200 - 600 shots total 1 - 3 treatments Photodisruption

LASER SURGERY

COMPLICATIONS

elevated intraocular pressure chroidal micro hemorhage retinal detachment cataract

VITREOUS BANDS AND MEMBRANES

They consist of hyalocytes, fibrocytes and endothelial cells of the capillaries.

They cause oedema, haemorrhage and hole formation in the retina. Why?

This is may be followed by RD. TTT: PP vitrectomy.

PERSISTENT HYPERPLASTIC PRIMARY VITREOUS

Etiology: failure of primary vitreous

structure to regress after birth.

Symptoms: White reflex is seen in the

papillary area. it may be associated

cataract, glaucoma, microphthalmos, intraocular haemorrhage.

PERSISTENT HYPERPLASTIC PRIMARY VITREOUS

Diagnosis: It is diagnosed by

CT. Treatment: Lensectomy and

vitrectomy

VIREOUS HAEMORRHAGE

Types:There are two types of vitreous haemorrhage:

1. Preretinal or subhyaloid haemorrhage: 1. The haemorrhage occurs between the retina and

the vitreous. 2. The blood remains fluid, red in colour and moves

with gravity . 2. IntraVitreal haemorrhage: The

haemorrhage may get absorbed or degenerate to form a white fibrous tissue mass.

Intravitreal haemorrhage

subhyaloid haemorrhage

Etiology:

1. Trauma 2. Vitreous traction.3. Diabetes mellitus.4. Central retinal vein thrombosis.5. Eale's disease: It is due to retinal

vasculitis and periphlebitis. 6. Malignant hypertension7. Blood diseases: Leukemia, sickle cell

anaemia, etc.

Symptoms:

1. Black spots or cloud may be seen in front of the eye.

2. There is impaired vision. It may be reduced to perception of light.

Signs:

1. Fundus examination:i. No red reflex is seen. ii. Grey opacities may be present in the vitreous.

2. Slit-lamp examination: Fresh blood or clotted blood may be seen in the vitreous.

Complications:

1. Complicated cataract may occur. 2. Retinal atrophy may be present due

to haemosiderosis.3. Retinal detachment may occur due

to organized fibrous tissue bands…..TRACTION

Treatment:

1. Bed-rest with elevation of head. 2. Photocoagulation: It is done if new

vessels or retinal tears are seen. 3. Vitrectomy: It is done after 3 months

if no visual improvement

VITREOUS LOSS

Definition: Herniation of vitreous

only in the anterior chamber or outside the eye.

Etiology:Accidental vitreous loss may occur during surgery on the lens, cornea and iris.

Signs:

1. Corneal oedema due to endothelium touch.

2. Updrawn pupil due to attachment of vitreous between the papillary margin and wound.

3. Macular oedema. 4. Aphakic glaucoma

due to papillary block.

Treatment:

Anterior vitrectomy By vitrectomy machine, or By vitreous scissors is performed

through a large corneal section .

VITREOUS INFLAMMATION

Vitreous is an excellent culture medium for the growth of bacteria and fungus leading to endophthalmitis and vitreous abscess formation.

Signs of endophthalmitis

The presence of WBCs lead to formation of fibrous connective tissue >>>>>>retinal detachment due to contraction.

TTT: Medical IO injection Vitrectomy

VITRECTOMY

Excision and replacement of the vitreous is known as vitrectomy.

Indications for vitrectomy:

1. Persistent vitreous opacity. i. Haemorrhage.ii. Vitreous membrane and bands.iii. Preretinal membranes.

Indications for vitrectomy:

2. Complications of cataract extraction:i. Loss of vitreous. ii. Vitreous touch with bullous keratopathy.iii. Incarceration of vitreous in wound.iv. Malignant glaucoma.v. Removal of intraocular lens or nucleus from the vitreous cavity.

3. Endophthalmitis with vitreous abscess.

Indications for vitrectomy:

4. Trauma:i. Intraocular foreign body. ii. Subluxated or dislocated lens.

5. Complicated retinal detachmenti. Vitreous traction by fibrovascular bands.ii. Gaint retinal tear. iii. Retinal dialysis.

6. Congenital cataract (lensectomy).7. Persistent hyperplastic primary

vitreous.

TYPES OF VITRECTOMY

Anterior vitrectomy PP vitrectomy 3.5mm from

limbus = pars plana

VITREOUS SUBSTITUTES

Liquid: Normal saline, BSS (balanced salt solution), silicone oil, sodium hyaluronate (Healon). Perfluorocarbon liquids (PFCL), etc.

VITREOUS SUBSTITUTES

Gas:a. Air.b. Sulfur hexafluoride (SF6).c. Perfluoro-propane (C3F8) d. Octa-fluoro-cyclo-butane (C4F8).

Thank you for your

attention

Abdelmonem.hamed@gmail.com