disorders of the vitreous and vitreo-retinal interface

describe the vitreous (recap) (3)

• Type of connective tissue about 99% H₂0, (also collagen fibrils, hyaluronic acid & other)

• Transparent, avascular, ‘Jelly’ like structure

• Occupies 67-75% of eye volume (4ml)

functions of the vitreous (5)

•Give shape and form to the eye

•Keep the retina in place

•Provide optical clarity - therefore needs to be optically clear

•Act as a shock absorber

•Inhibits neovascularisation

anatomical points of the vitreous (2)

•Vitreous cortex/posterior hyaloid membrane/surface - condensation of collagen fibrils

•Strong vitreoretinal adhesion at certain points (vitreous base (ora seratta) > optic nerve, scars > blood vessels, macula)

what are the processes involved with the normal ageing of the vitreous (3)

• Liquefaction (Synchysis) AND

• Fibre density increases (>40 yrs) leading to…

• Shrinkage (syneresis) occur

describe liquefaction - synchysis (3)

•Increasing liquefaction from 2^nd decade

•Lacunae (fluid filled spaces) develop, increase in size & coalesce

•By 70 years ~50% liquified

Describe the increase of fibre density (2)

•Collagen forms clumps which reduce light transmission

•Vitreous strands and floaters

describe shrinkage (syneresis) (2)

•Vitreous pulls away from the retina - posterior vitreous detachment (PVD)

•NB: Areas of strong vitreoretinal adhesion can lead to abnormalities

describe what vitreous floaters are (2)

•Small, dark or translucent dots and filaments in vitreous

• common - Occur in all age groups (usually older due to ageing vitreous)

what are the causes of vitreous floaters (3)

•Most often - normal aging vitreous

•Earlier in myopes, trauma, inflammation, certain diseases

•Always keep in mind serious causes - symptoms in addition to floaters are important !!! - flashing lights as well may indicate something in retina - can be benign but always check

what are the symptoms of vitreous floaters

•Patient reports floating object - dots, lines, spider web, various shapes

•Most obvious against white background

what are the signs of vitreous floaters (1)

•Not always detectable with ophthalmoscope

what is the management of vitreous floaters (3)

• Reassurance is main therapy - double check however odd floater here and there is usually okay

• if new/large floaters/new shower of floaters - red flag

• Can be surgically removed if particularly troublesome - rare

why may congenital vitreous anomalies arise

•Incomplete hyaloid artery regression - leaving anomalies which we can see when examining px eye

name and describe congenital vitreous anomalies we may see ()

• Persistent hyaloid artery - Coming from the disc (with or without blood)

• Mittendorf dot - Small opacity on posterior lens capsule

• Bergmeister’s papilla - Clump of glial tissue on disc

what is the management of congenital vitreous anomalies

• benign and do not require treatment - asymptomatic

state the different vitreous abnormalities to know (5)

1. Persistent foetal vasculature !

2. Vitreous Cysts !

3. Asteroid Hyalosis !!

4. Synchysis scintillans !!

5. Vitreous haemorrhage !!!

describe what persistent foetal vasculature is (4)

•Also known as - Persistent Hyperplastic Primary Vitreous (PHPV)

•Persistence of the hyaloid system (incomplete regression) resulting in fibrovascular proliferation - rare

•Anterior form: around the lens.

•Posterior form: around the retina and optic disc

what is the management of persistent foetal vasculature

immediate referral and treatment by paediatric ophthalmologist

what are the associations with persistent foetal vasculature

• Other congenital anomalies (cataract, glaucoma microphthalmos)

differential diagnosis of persistent foetal vasculature

• leukocoria - white/pale pupil appearance

what are vitreous cysts (3)

•Extremely rare

•Normal incidental finding or associated with ocular pathology

• congenital/acquired

describe congenital vitreous cysts (3)

•Located at hyaloid canal

•Associated with Mittendorf's dot or Bergmeister's papillae

•Non-pigmented pearly-grey, smooth surface

describe acquired vitreous cysts (4)

•Trauma, inflammation/infection

•Retinal disease (RP, retinoschisis, choroidal atrophy)

•Retinal detachment surgery

•Usually reduced VA

describe asteroid hyalosis (4)

•Sometimes called Benson’s disease

•Fairly common (1 in 100), usually > 55 years old and unilateral

•Small yellow-white spheres

•Composed of calcium-phospholipid complexes suspended throughout the vitreous (stable/static) - as px looks around they stay still

what are the sx and management of asteroid hyaloisis (4)

•Usually asymptomatic

•No effect on vision

•Self-limiting and benign

• Patient education - routine review

describe synchisis scintillans (4)

• bilateral vitreous disorder in the young - RARE - probably occurs in only blind, severely damaged eyes

• Numerous reflective small angular yellow crystals floating throughout vitreous - mobile in vitreous - swirl round as px moves eye

• crystals float around in a shower then settle to bottom of vitreous

• Composed of cholesterol (not associated with high serum cholesterol)

sx and signs of synchisis scintillans

•Usually asymptomatic - not much management to do

•Thought to follow trauma or inflammation

describe the vitreoretinal interface

• Vitreous cortex and ILM of retina adhere via a molecular glue

• Intervening extracellular matrix (fibronectin, laminin, collagen and other extracellular components)

• as we age this adhesion weakens and can lead to abnormalities… like a vitreous haemorrhgae / PVD - in this lecture

describe the aetiology of a vitreous haemorrhage (6)

• Blood enters vitreous - Disc vessels, retinal vessels, choroid

Causes:

• Diabetic retinopathy (32-54%)

• Trauma (12-19%)

• Retinal tear or detachment (11-44% of cases)

• Posterior vitreous detachment (4-11% of cases)

• Others: retinoschisis, vein occlusion, sickle cell retinopathy, AMD etc.

what are the symptoms of a vitreous haemorrhage (4) (variable)

•Painless loss of vision

•Sudden, significant increase in the number and size of floaters (asking about floaters imp!!!)

•Blurry, cloudy or hazy vision (small bleed)

•Large bleed may obscure vision

how can we examine a patient with a vitreous haemorrhage (6)

•Vision/visual acuity

•Slit-lamp examination - looking directly at retina and anterior/posterior vitreous

•Eye pressure - can be reduced/increased

•Dilated eye examination

•Gonioscopy - peripheral retina and anterior angle

•B-scan ultrasound - hospital setting

describe the signs of a vitreous haemorrhage (2:1)

Non-dispersed:

• Clear red haem - dense dark red/brown patch

• Pre-retinal (boat shaped) - posterior to vitreous

Dispersed:

• Obscuration of view - blood disperse through vitreous

describe the prognosis of a vitreous haemorrhage

•Variable depending on cause - sometimes can clear and vision will be restored or…

•Fibrovascular proliferation may result which could lead to scarring and contraction and ultimately retinal detachment

management of a vitreous haemorrhage (1)

•Emergency/same day (within 24 hours) referral

secondary care of a vitreous haemorrhage (4)

•Further examination/Mx

•B-can, Gonioscopy, IOP …. to find cause

•Treat the cause

• Monitor or vitrectomy

describe posterior vitreous detachment (5)

• Separation of vitreous cortex and neurosensory retina – part of normal ageing process - very common

• Incomplete: involves posterior region

• Complete: extends to ora serrata (vitreous base)

• Most eyes 80+ years - Onset typically 60-70 years

• Can be associated with myopia, trauma or inflammation

what are the symptoms of a PVD (3)

• Sudden onset of floaters (most common) - ‘Cobwebs’ ‘bugs’ ‘spots’ (not usually a ‘shower’ - which may indicate retinal break) - Change position with eye movement

• Photopsia (flashes of light 25-50%) - Dim illumination, temporal VF

• Metamorphopsia - distorted vision - (less common) - If vitreo-retinal traction at macula

state and describe the main sign of a vitreous haemorrhage (3)

• weiss ring - classic sign - unusually large floater

• Grey/black annular ring suspended above disc on posterior hyaloid face - circular, doughnut-shaped floater in vision

• Complete or incomplete

state and describe other signs of a PVD (2)

• Visible posterior hyaloid face

• Peripheral pre-retinal and disc margin haemorrhages

describe complications that can arise with a PVD (5)

• Strong association with retinal tears and detachment (10-15%)

• Risk of retinal detachment greatest in first 6-8 weeks

• Shafer sign (tobacco dust) RPE cells in anterior vitreous (90% have a retinal break)

• Vitreous haemorrhage (70% have a retinal break)

• Macular hole formation (tractional)

optometric management of a PVD

All acute onset PVDs require:

• Detailed H & S - risk factors

• Examination of the anterior vitreous - pigment cells

• Dilated fundus examination, using an indirect technique - peripheral retinal breaks

• Unable to carry out an adequate examination, you must refer to a practitioner who is competent to do so

• Patient education - signs/symptoms of retinal detachment - give written and verbal explanation - imp to go to A&E if sx persist or new sx !!

•Re-examination within 6-8 weeks of first report of symptoms may be indicated (not a requirement)

•Retinal break, vitreous haemorrhage or Tobacco dust - same day referral to ophthalmologist

•Follow local protocols and keep full and accurate records of all patient contact

NICE guidelines