Vitreous substitutes in ophthalmology

VITREOUS SUBSTITUTES
PRESENTOR:MD ALBAN UDDIN
MODERATOR:DR VIJAY.N

CONTENTS
• Anatomy of vitreous.
• History of vitreous substitutes.
• Intraocular gases.
• Silicon oil.
• Perfluorocarbon liquids.
• Miscellaneous materials.

VITREOUS HUMOUR
• Inert,transparent,colourless,jelly-like,hydrophilic gel.
• Largest and simplest connective tissue present as a single piece in human body.
• Fills posterior 4/5th of globe with retina behind and ciliary body,zonule and lens in
front.
• Weighs 4g and occupies a volume of 4cc-approx. 2/3 of volume of entire globe.
Wolff’s anatomy of eye-pg no.446

• COMPONENTS:
1) Cortex: Anterior hyaloid
Vitreous base
Posterior hyaloid
Peripapillary and perimacular attachments
2)Central vitreous
3)Vitreous cells

PROPERTIES OF VITREOUS
• Water-99%
• Solids-1%-macromolecular and micromolecular.
• Macromolecular-Collagen,hyaluronic acid,soluble proteins.
• Low molecular weight constituents-sugars,ascorbic acid,amino acids.
• Electrolytes: Sodium, Potassium, Calcium, Chloride, Bicarbonate, Phosphate,
Lactic acid
• Wolff’s anatomy of eye-pg no.448

FUNCTIONS OF VITREOUS
• Metabolic.
• Transportation of materials.
• Forms blood-vitreous barrier.
• Maintains transparency of medium.
• Resist disorganising forces.

HISTORY
• 1917-Ohm-first intravitreal air injection.
• 1938-Rosergen-founded the concept of internal tamponade by air.
• 1973-Norton-SF6 injection with scleral buckling or vitrectomy.
• Blodi and folk-treated detachments due to macular hole using intravitreal gas.
• Dominguez et al-used expansive gases to treat retinal detachments.
• Hilton and gizzard-Pneumatic retinopexy.
Ryan’s retina-6th ed,vol 3,pg no 1943

MATERIALS
• Intraocular gases.
• Silicone oil.
• Perfluorocarbon liquids(PFCL).
• Miscellaneous

INTRAOCULAR GASES
NON EXPANSILE GASES EXPANSILE GASES
Air Sulfur hexafluoride(SF)
Nitrogen Perfluoromethane(CF)
Helium Perfluoroethane(C2F6)
Oxygen Perfluoropropane(C3F8)
Argon Perfluorobutane(C4F10)
Krypton Perfluoropentane(C5F12)
Carbon dioxide Octafluorocyclobutane(C4F8)
Xenon

PHYSICAL PROPERTIES OF IDEAL INTRAOCULAR
GAS
AVAILABILITY:
• Readily available
• Not expensive
BIOCOMPATIBILITY AND SAFETY:
• Non toxic
• Odorless
• Colorless
• Inflammable
• Not cause lens opacity
WATER SOLUBLE
STABLE WHEN MIXED WITH AIR

CHARACTERISTICS OF GASES
• SURFACE TENSION:
• Highest surface tension among all vitreous substitutes.
• If bubble is larger than the break then the surface tension of the gas prevents it
from passing through the break.
• Leads to occlusion of the break.
• BUOYANCY:
• Property to float.
• Force which pushes the uppermost retina back.
• Helps in opposition of retina to choroid.

COMMOMNLY USED GASES
• Air
• Sulfur hexafluoride
• Perfluorocarbon gases

• AIR:
• Initial gas to be tried in retinal surgeries.
• Non expansile
• Advantages: IOP is restored after air injection
Surface tension of air bubbles enables retina to be opposed and
attached
Non expansile-no traction to inferior retina and new break formation
Decreased expense
Universal availability

• DISADVANTAGES:
• “fish eggs”due to poor injection technique.
• Larger volume has to be injected.

• SULPHUR HEXAFLUORIDE(SF6):
• Odorless,colorless,inflammable,inert gas.
• Expands 2x its original volume in 36 hrs after injection.
• Used as 20% SF6 and 80% air as non expansile form.
• Provides a large area of tamponade.

• PERFLUOROCARBON GASES:
• Generic formula Cx F2x+2 -where x can be 1 to 4.
• Inert,odorless,colorless gases.
• Water solubility is inversely proportional to length of carbon chain.
• Increased molecular weight leads to greater expansion and longevity of these
gases.

DYNAMICS OF GAS BUBBLE IN THE EYE

• EXPANSION:
• Due to higher rate of diffusion of nitrogen into the bubble than the rate of gas
dissolving in surrounding tissue.
• Initial 6-8 hrs-most rapid.
• Gaseous diffusion in and out of bubble equlibriates-maximum size.
• SF6-1-2 days,C3F8 3-4 days.
• Leads to IOP rise,eyes with occludable angle,avoid using pure expansile gas.

• EQUILIBRATION:
• Partial pressure of nitrogen is equal to that of surrounding fluid compartment.
• Small movement of expansile gas into surrounding fluid compartment-bubble size
diminishes slightly.
• Differs for different expansile gases,dependant upon solubility.

• DISSOLUTION:
• Partial pressure of all the gases within the bubble equals that in the fluid
compartment.
• Longest phase-6-8 weeks for bubble to resorb.
• Tamponade effective only in initial 25% of bubble’s lifespan as 50% of initial size
of bubble is required to provide effective tamponade.
• Lens status, aqueous turnover, presence of vitreous, preretinal membranes,
ocular blood flow, ocular elasticity-effect duration of resorption of bubble.

CONSIDERATIONS UNDER GENERAL
ANAESTHESIA
• Nitrous oxide-34x more soluble than nitrogen and 117x more soluble than SF6.
• N2O diffuses quickly into bubble and increases volume-SF6 3 times of original.
• Maximum IOP may rise 15-20 minutes of nitrous oxide use and decreases once
discontinued.
• N2O to be discontinued atleast 15 minutes prior to intraocular gas injection.
• CRAO and choroidal ischaemia have been reported due to uncontrolled rise in
IOP during surgery.
• Every patient with intraocular gas bubble to be given a wristband indicating time
and type of intraocular gas to be worn throughout lifespan of bubble.

RESPONSE TO CHANGE IN ALTITUDE
• Air travel-rapid expansion of bubble-IOP rise.
• Scuba diving-IOP may increase when diver returns to surface

FUNCTIONS OF GAS
1)INTERNAL TAMPONADE:
• Main indication.
• Due to surface tension-opposes break.
• Initially small bubble-rounded shape initially-less arc of contact.
• Next 24-48 hrs,bubble expands- “Spherical cap”.
• Also seals off break-prevents proliferative vitreoretinopathy.

• Unfolding of the retina:
• Surface tension and buoyancy helps to unfold the retina after drainage of SRF.
• Postoperative visualisation :
• Helps visualisation of fundus by overcoming vitreous haemorrhage after
vitrectomy and gas tamponade.
• Replace globe volume:
• Prevents SRF fluid being recruited again.
• Restores IOP.

CLINICAL APPLICATIONS
• RETINAL DETACHMENT SURGERY WITH VITRECTOMY:
• Used to flatten retina after full vitrectomy and relieving of tractions.
• Provides easy visualisation of retina for endolaser.
• Short duration procedure-use air.
• Complicated cases with requirement of longer tamponade-use non expansile
concentration of gas/air mixture(18% SF6 or 14% C3F8).
• Larger bubble needed-use gas/air mixture with expansile concentration.

• PNEUMATIC RETINOPEXY:
• Prerequisites:
• Retinal detachment has to be in superior half of retina.
• Break or hole is solitary or grouped within 1-2 clock hours.
• There are no inferior breaks or retinal thinning.
• GAS USED:
• 0.3% of 100% C3F8 used most commonly.
• Same volume of SF6 can also be used.

• PROCEDURE:
• Inject gas after adequate cryotherapy.
• Injection should be on the side of the break.
• Gas is injected through a 27G needle,3.5-4mm behind limbus.
• Rotate injection site such that it is in uppermost position to avoid fish-egg
formation.
• Rotate injection site laterally before pulling needle out to ensure that bubble
moves away from injection site.
• If fish-egg has formed,tap sclera gently,promotes fusion of small bubbles.
• AC paracentesis can be done to counter raised IOP.

• SCLERAL BUCKLING FOR RD:
• When “fish-mouthing” of the break in a circumferential buckle is seen and is
insufficiently opposed by the buckle.
• Acts as adjunct.
• Superior breaks with minimal SRF-air
• Inferior breaks with fish mouthing-0.3ml of expansile C3F8.

• MACULAR HOLE SURGERY:
• Provides tamponade
• Gas injection is followed by face down procedure for 1 week.
• Provides a buoyancy force of bubble over macular hole-assists closure.
• Choice of gas- 12% of C3F8.

• DISPLACEMENT OF SUBRETINAL BLOOD:
• Therapeutic.
• Speedier recovery of vision.
• Reduces harmful effect of blood on photoreceptors.
• Treat within 1 week of onset of haemorrhage with TPA activator injection.
• Choice of gas-0.3 ml of 100% C3F8 with/without TPA.
• Strict face down posture for few days post injection.

• POSTVITRECTOMY GAS EXCHANGE:
• For recurrent RD,can avoid the need for reoperation.
• Gas-gas exchange-when patient is required to undergo air travel before
dissolution of air bubble,bubble of shorter longevity could be exchanged.
• Can be done in a slit-lamp with a 30G needle.
• Needle inserted at 3.5-4mm posterior to limbus at inferotemporal quadrant.
• Done via a push-pull technique.
• Choice of gas
• Larger bubble required-expansile gas.
• Smaller bubble-air or nonexpansile concentration of gas/air mixture.

POSTOPERATIVE CARE
• Face-down posture-proper opposition of break,reduces cataract development,
prevents pupil block.
• Monitor IOP within first post-op day
• Refrain from changing altitudes.

COMPLICATIONS
• CATARACT FORMATION-feathery posterior subcapsular cataract.
• RAISED IOP-due to expansion of gas which cannot be coped up with outflow
facility.
• HYPOTONY-leak of gas from sclerotomy.
• SUBRETINAL GAS-smaller bubble than the tear or due to persistent traction.
• GAS IN AC AND CORNEAL DECOMPENSATION-in aphakic or pseudophakic
eyes,corneal endothelium hypoxia and decompensation.
• IOL CAPTURE-due to pushing of IOL in AC.

MANAGEMENT
• CATARACT-Assume a prone position, leave a thin layer of hyaloid. Mild forms
may resolve, longer forms-removal.
• RAISED IOP-Antiglaucoma medications, excess gas can be aspirated.
• HYPOTONY-Risk of choroidal haemorrhage, reinject more gas.
• SUBRETINAL GAS-Look for presence of retinal traction, reoperation may be
required.
• GAS IN AC AND CORNEAL DECOMPENSATION-Avoid lying down in
supine position.
• IOL CAPTURE-Limit anterior capsulorrhexis to a size smaller to that of optic
of IOL. Repositioning if dislocation has occurred.

SILICONE OIL(SO)
• First introduced in early 1960s by Paul Cibis.
• Initially used to overcome tractional forces and the dissection of preretinal
membranes, later discontinued owing to complications and toxic effects.
• In 1980s,SO had re-established its role as an internal tamponade agent in many
European countries.

• CHEMICAL PROPERTIES:
• Made up of repeating units of siloxane.
• Siloxane consists of a silicone and oxygen molecule[-Si-O-].
• Can be lighter or heavier than water, depends upon side chain
• Heavier than water SOs(polydimethylsiloxane and semifluorinated alkanes) are
designed for inferior tamponade purposes.
• Lighter than water SOs tend to promote emulsification.
• Commercially available SOs are sold and classified according to their average
viscosities.

PHYSICAL PROPERTIES
• SPECIFIC GRAVITY:
• Polydimethylsiloxanes(PDMS) all have a specific gravity of 0.97(lesser than
aqueous and water).
• BUOYANCY:
• Has lesser buoyancy than gas, makes no contact with retina until eye is 50% filled.

• SURFACE TENSION:
• Interfacial tension-keeps the bubble as a whole.
• Oil bubble remains intact as long as interfacial tension is above 6 mN/m.
• With physiologic fluid-33mN/m,with blood-14nm/N.
• VISCOSITY:
• Addition of high molecular weight polymers to low viscosity SO increases
extensional viscosity.
• Addition of 5% or 10% of 423kD to 1000 cSt SO,increases shear viscosity to
2000cSt and 5000cSt.

INDICATIONS
• RETINAL DETACHMENT WITH PVR:
• In cases where previous vitrectomy has not achieved retinal attachment.
• In eyes with IOP less than 5mmhg and severe retinal detachment.
• Buckling of an inferior tear.
• No need for postoperative posturing,and patient
can do air travel.
• Contraindication:Deficient iris diaphragm(aniridia),
may predispose to keratopathy.

THE SILICONE STUDY
• Multicenter, prospective randomized clinical trial.
• To compare the postoperative tamponade effectiveness of intraocular
silicone oil with that of an intraocular long-acting gas (SF6 and C3F8) for
the management of retinal detachment complicated by proliferative
vitreoretinopathy (PVR), using vitrectomy and associated techniques.
• SO was found to be as effective as C3F8 and better than SF6 in reattaching
retina.
• Both SO and C3F8 were equivalent in terms of improving visual function
and low complication rates.
• SO was better compared to SF6 in terms of postoperative
complications(hypotony and keratopathy).
• Silicone Study Group. Vitrectomy with silicone oil or sulfur hexafluoride gas in eyes with severe proliferative
vitreoretinopathy: results of a randomized clinical trial: Silicone Study report 1. Arch Ophthalmol 1992;110:770–9.

• In eyes with no previous history of vitrectomy,that required retinotomy to flatten
retina,SO greatly increased likelihood of visual recovery and reduced risk of
hypotony at 6 months.
• At 24 months,deteriorating trend was observed in eyes which used SO and
improving trend was seen in the eyes which used intraocular gas.
• Silicone Study Group. Vitrectomy with silicone oil or sulfur hexafluoride gas in eyes with severe proliferative vitreoretinopathy: results of a randomized clinical trial:
Silicone Study report 1. Arch Ophthalmol 1992;110:770–9

• GIANT RETINAL TEARS:
• Unfolding of folded retina.
• To act as external tamponade agent.

• SEVERE PDR:
• Tractional RD with severe PDR.
• Enables rapid visual recovery.
• Reduces post-operative haemorrhage.
• Enables clear visualisation of fundus during examination.
• Better tamponade for those who cannot posture after operation.
• Confines all dissolved oxygen in anterior chamber.
• Prevents proliferative factors from posterior chamber
coming anteriorly,prevents anterior segment neovascularisation.
• DRAWBACK-Need for second operation to remove from eye.

• MACULAR HOLE:
• Idiopathic macular hole-vitrectomy with or without ILM peeling,followed by
internal tamponade with either gas or SO,combined with postoperative facedown
position.
• Goldbaum et al-80% closure rate with vitrectomy and SO tamponade.Lai et al
reported a lower closure rate with SO1.
• Gas tamponade has shown a higher success rate as compared to SO from
POD11.SO can be considered for those who need to travel by air after surgery.
• RD with macular hole in pathological myopia-Chen et al reported reattachment
was in favour of SO2.
1. Goldbaum MH, McCuen BW, et al. Silicone oil tamponade for idiopathic macular hole surgery. Ophthalmology 1998;105:
2140–7.
2.K, Yamakiri K, Arimura N, et al. Posturing time after macular hole surgery modified by optical coherence tomography
images: a pilot study. Am J Ophthalmol 2009;147:481–8.e2.
3. Nishimura A, Kimura M, Saito Y, et al. Efficacy of primary silicone oil tamponade for the treatment of retinal detachment
caused by macular hole in high myopia. Am J Ophthalmol 2011;151:148–55.

• VIRAL RETINITIS:
• Diffuse,relentless,and have a high redetachment rate due to necrosis.
• SO offers long-term,sometimes permanent,internal tamponade and reduces the risk of
redetachment.
• Patients with CMV retinitis-tend to devlop cataract with median age of 1.8 months after retinal
detachment repair with SO,following phacoemulsification,they developed PCO within 7 days1.
• Clear lens extraction with in such patients at time of retinal detachment repair with SO
tamponade may be beneficial(20/75 before surgery to 20/50 after surgery)2.
• Intravitreal ganciclovir with SO after surgery,gets concentrated in retina,increases toxicity,use
ganciclovir implant.
1.Tanna AP, Kempen JH, Dunn JP, et al. Incidence and management of cataract after retinal detachment repair with silicone oil in immune compromised patients with
cytomegalovirus retinitis. Am J Ophthalmol 2003;136:1009–15.
2.Engstrom RE Jr, Goldenberg DT, Parnell JR, et al. Clear lens extraction with intraocular lens implantation during retinal detachment repair in patients with Acquired Immune
Deficiency Syndrome (AIDS) [correction of autoimmune deficiency syndrome] and cytomegalovirus retinitis. Ophthalmology 2002;109:666–73. [Erratum in: Ophthalmology 2002;
109:1588].

• COMPLICATED PEDIATRIC RD:
• RD associated with trauma, ROP, coloboma, optic disc pit and myopia.

• RD ASSOCIATED WITH CHOROIDAL COLOBOMA:
• Pal and associates reported long term attachment rate of 88.61% with vitrectomy
and SO tamponade at 6 months compared to 60% with radial explants.
Pal N, Azad RV, Sharma YR. Long-term anatomical and visual
outcome of vitreous surgery for retinal detachment with
choroidal coloboma. Indian J Ophthalmol 2006;54:85–8.

• TRAUMA:
• SO provides internal tamponade which helps to flatten retina and prevent
haemorrhage.

• ENDOPHTHALMITIS:
• SO has been suggested to possess antimicrobial activity.
• Azad et al reported vision of 20/200 or better in 58% of cases compared with 8%
in a prospective RCT comparing effect of vitrectomy with and without SO
tamponade for postoperative endophthalmitis.
• . Azad R, Ravi K, Talwar D, et al. Pars plana vitrectomy with or without silicone oil endotamponade in posttraumatic
endophthalmitis. Graefes Arch Clin Exp Ophthalmol 2003;241: 478–83

TECHNIQUE OF SILICON OIL INFUSION
• GENERAL CONSIDERATIONS:
• Commercially available silicon oil has viscosities ranging from 1000cSt to 5000cSt.
• Difficulty of injection is higher as viscosity goes up.
• Ease of removal is higher as viscosity goes down.
• Risk of emulsification.
• High pressure is required to infuse SO from eye into container.
• 5-10ml of SO is sterilized and stored in a 20ml container.
• Infusion can be made from either of two open sclerotomies.
• Infusion can be done through a short metal or plastic cannula or automated
infusion pump.
• Infusion pump is faster,but no preesure-feedback system,IOP has to be monitored
digitally.

AIR SILICON EXCHANGE
• Air-fluid exchange has to be performed prior to it.
• Retina should be flat with no or minimal SRF,vitreous predisposes to underfill.
• Endolaser photocoagulation has to be performed to seal all retinal breaks.
• Can be done through either of the sclerotomies.
• Illumination probe should be withdrawn to allow air to escape.
• End point-filling up of vacant sclerotomy.
• Aphakic-SO reaches iris plane.
• Pseudophakics-SO bubble touches posterior capsule.
• IOP-around 10mmhg,if not-overfill.leads to shallow AC and
IOP rise,express SO through sclerotomy.

PFCL-SILICON OIL EXCHANGE
• Useful in conditions where there is slippage-
fluid pocket get trapped anteriorly and get pushed
under retina as PFCL is removed leading to
circumferentially oriented folds in quadrant
of the tear

COMPLICATIONS
• SILICONE OIL IN AC:
• Iris diaphragm is inadequate to stop SO from migrating into AC-aphakia,loose
zonular support,blockage of inferior peripheral iridectomy,break in posterior
capsule.
• Confirmatory signs-posterior iris,shimmering reflex in iris crypts,absence of
aqueous flare in AC,mid-dilated pupil with raised IOP.
• Can be displaced back into vitreous cavity with air or viscoelastic agents.
• Peripheral iridectomy needs to be done.
INVERSE HYPOPYON/HYPEROLEON

• GLAUCOMA:
• Can be due to:
1)Pupil block glaucoma
2)Overfill of SO
3)Secondary open angle glaucoma
4)Migration of SO into AC
5)Secondary angle closure glaucoma

• Pupil block glaucoma:when PI is not functioning or due to blockage by fibrin
products or blood.
• Treatment-reopening of PI with YAG laser or surgically.Injection of tPA if block is
by fibrin or clot.
• Over fill of SO:SO can come infront of crystalline or intraocular lens and
herniating through pupil.
• Treatment-Removal of oil through through corneal or pars plana incision.monitor
pressure during surgery.
• Secondary open angle glaucoma:mechanical blockage of trabecular meshwork
or trabeculitis.
• Treatment:Medication,glaucoma drainage device.
• Secondary angle closure glaucoma:Diagnosis of exclusion.
• Refractory cases,use transscleral cyclodiode photocoagulation.

CHRONIC HYPOTONY
• Defined as IOP≤5mmhg according to the Silicone study.
• Patients may have eye which is relatively normal or may have swollen optic disc
and macular edema.
• Combination of increased aqueous uveal-scleral outflow and reduced production.
• Large retinectomies-increased uveal-scleral outflow.
• Ciliary body alterations-reduced aqueous production.
• Prevalence of hypotony in the Silicone study was 18% at 36 months.
• Treatment has been disappointing.
• Removal of membranes over ciliary body and ciliary processes(may be cause of
hyposecretion) has been suggested.
• Removal of SO may lead to pthisis.avoid with <10mmhg IOP.
• Silicone Study Group. Vitrectomy with silicone oil or sulfur hexafluoride gas in eyes with severe proliferative vitreoretinopathy: results of a randomized clinical trial:
Silicone Study report 1. Arch Ophthalmol 1992;110:770–9

• CATARACT FORMATION:
• Multifactorial causage,inevitable.
• Due to SO, vitrectomy or surgical trauma.
• Exact mechanism unclear,maybe due to impaired metabolic exchange or due to
direct toxicity.
• Specific feature-vacuoles in posterior part of lens.
• Posterior subcapsular feathery opacity nuclear sclerosis hypermaturity.
• Can opt for combined phacovitrectomy.
• SO in posterior chamber gives a false high axial length,B-mode axial length
measurement to be done prior to surgery.
• Specific SO-formulae to be used when calculating IOL power.

• RECURRENT RETINAL DETACHMENT:
• Mainly due to missed retinal breaks.
• Prophylactic 360◦ laser retinopexy can be considered in high risk patients as an
adjunct to enhance the chance of anatomic success after SO removal.
• . Laidlaw DA, Karia N, Bunce C, et al. Is prophylactic 360-degree laser retinopexy protective? Risk factors for retinal redetachment after removal of silicone oil.
Ophthalmology 2002;109:153–8

• EMULSIFICATION:
• Occurs when surface energy of smaller
droplets is reduced in presence of
surfactants(phospholipids,protein
Lipoprotein or solid cellular debris).
• Likelihood inversely proportional
To viscosity.
• Can lead to glaucoma,inflammation
and PVR retinopathy.
• Addition of very high molecular weight
polymers to low viscosity SO can reduce
rate of emulsification.

• KERATOPATHY:
• Prolonged use.
• Band keratopathy-early stages.
• Bullous keratopathy-later stages.
• Risk factors-pseudophakic or aphakic before surgery, neovascularization before
surgery, postoperative aqueous flare and need for reoperation.
• Contact between SO and corneal endothelium-major risk factor.
• Preventive measure-patent peripheral iridectomy and removing SO as soon as
practical.

SILICONE OIL REMOVAL
• when the bubble has served its purpose and increased retention can lead to
complications.
• Removal within first 6 months is recommended.
• Retention of emulsified bubbles,patient may complain of
floaters.

PERFLUOROCARBON LIQUID
• Initially designed for use as a blood substitute.
• Was used in coronary angioplasty to deliver oxygen to ischaemic myocardial
tissue.
• Has high oxygen carrying capacity and is chemically inert.
• 1982-Haidt and associates first examined its use as a vitreous substitute.
• 1987-Chang investigated the possibility of PFCL as an intraoperative tool to assist
manipulation of retina in complicated retinal detachment.

TYPES AND PROPERTIES
• Synthetic fluorinated hydrocarbon containing carbon-fluorine bonds.
• Some contain hydrogen,bromide and nitrogen.
• Colorless,odorless,low viscosity and higher specific gravity and density than
water.
• Stable at high temperatures,do not absorb wavelengths of commonly used lasers.
• Perfluoro-n-octane-approved by FDA for use.

ADVANTAGES
• Optical clarity allows manipulations possible.
• High density and specific gravity-allows flattening of retina and unrolling of folds.
• Different refractive index from saline-visible PFCL-fluid interface,aids intraocular
maneuvers and ease of removal.
• Endophotocoagulation under PFCL-No interference to laser wavelengths.
• Low surface tension and high interfacial tension-holds PFCL in a big bubble and
reduces risk of migration into subretinal space.
• Low viscosity-easy injection and aspiration with small-gauge vitrectomies.
• Immiscibility with water-resists incursion by saline and blood and allows clear
operating field despite intraoperative bleeding.
• Immiscibility with SO-allows treating of giant retinal tears by reducing risk of
slippage.

INDICATIONS
• PROLIFERATIVE VITREORETINOPATHY:
• PFCL-allows dissection of membranes from posterior pole-reduces risk of
iatrogenic tears and trauma to eye.
• Shortens operative time and more thorough removal of membranes.
• Can also be used to provide tamponade.
• Less severe cases-PFCL-air exchange and tamponade with expansile air/gas
mixture.
• Severe cases-PFCL-SO exchange.

• GIANT TEARS:
• Before PFCL,giant retinal tears were repaired by rolling patient intraoperatively
into a prone position and unfolding of retina with help of a intraocular gas
bubble.
• PFCL allows entire surgery to be performed in supine position.
• Endophotocoagulation can be done.
• Left in situ for 1-2 weeks after which if
retina is stable,gas is used or else SO is used
to provide prolonged tamponade.

• OCULAR TRAUMA:
• ADVANTAGES:
1)Stabilises retina during vitrectomy.
2)Assist separating of posterior hyaloid and retina.
3)Displaces preretinal,subretinal and suprachoroidal blood.
4)Assists removal of incarcerated vitreous or retina.
5)Facilitates removal of dislocated lens,IOL or IOFB.
6)Maintains a clear media for visualisation.

• DISLOCATED LENS:
• For dislocated crystalline lens,dropped cataract fragments and intraocular lens.
• Small lens fragments are purchased using aspirator and then levitated to mid
vitreous cavity before activation of pulsed ultrasound fragmentation.
• Whole lens-PFCL used as a way of lifting lens to midvitreous cavity,then broken up
and removed by a cutter or ultrasound fragmentation.
• Can be used to float whole lens to AC
in aphakic eyes where it can be removed
through corneal or scleral wound.
• Dropped IOL-PFCL is used to float
up the IOL and then can be
delivered through limbus.

• SUPRACHOROIDAL HAEMORRHAGE:
• Blood-lighter than PFCL ,can be used to displace blood anteriorly towards
sclerotomy port where it can be drained.
• Partial drainage is achievable to relieve patient from pain.

COMPLICATIONS AND MANAGEMENT
• SUBRETINAL PFCL:
• May go into subretinal space during surgery or maybe seen under retina
postoperatively.
• Predisposing factors:
1. PFCL breaking into globules.
2. Giant retinal tears.
3. Incomplete relief of tractional membranes on retina.
• Should be removed with every effort during surgery, may migrate under
fovea,cause central scotomas.
• Long standing sub-retinal PFCL-Retinal hole formation.
• Done either through small drainage retinotomy adjacent to PFCL bubble or by a
peripheral retinotomy and inserting a flute directly under retina for drainage.

• INTRAOCULAR TOXICITY:
• Incomplete removal of PFCL.
• Higher risk with larger peripheral retinotomy(360°).
• Toxicity-chemical and mechanical.
• Chemical-due to high oxygen carrying capacity and polar impurities.
• High O2 carrying capacity-vasoconstriction of blood vessels and direct
damage(loss of pericytes and endothelial cells).
• Impurities-alters PFCL interface,make it less resistant to absorbing
lipoproteins,leads to formation of fibrotic membranes.

• MECHANICAL:compression of retina by retained PFCL,due to higher specific
gravity.
• Leads to loss of outer plexiform layer,displacement of photoreceptor nuclei into
outer segments,atrophy of RPE.

• PFCL IN ANTERIOR CHAMBER:
• Can cause visual disturbance,corneal endothelial loss ,rise in IOP.
• May block visual axis and cause disturbance of vision.
• Secondary open angle glaucoma and and pupillary block glaucoma.
• To prevent,PFCL can be aspirated through a syringe in a slit lamp with a 27G
needle.

MISCELLANEOUS
• Balanced salt solution:
• Can be used during retinal reattachment surgery to restore normal IOP.
• No tamponade effect.
• Not preferred-may pass through break and lead to retinal detachment.
Modern ophthalmology,3rd volume,dutta,pg no 1782

• SODIUM HYALURONATE(HEALON 1%):
• Used to restore normal IOP during air-fluid exchange,helps prevention of
Descemet’s folds due to hypotony.
• To evert posterior flap of giant retinal tear.
• To separate epiretinal membranes,
• COMPLICATION-Raised IOP

HEAVY TAMPONADE
• Specific gravity greater than water.
• Provide a tamponade effect on the inferior retina.
• The Heavy Tamponade Study(HSO Study)showed no significant difference
between heavy tamponade(Densiron 68) and SO regarding anatomic success as
well as visual outcomes.
• Densiron 68 is comparable to SO in terms of complication rates and in vivo
tolerability,

SUMMARY
• Intraocular gases-Highest surface tension and buoyancy,inexpensive.
Need posturing,short term of action.
• Silicon oil-Has a wider area of application.
Longer action.
• PFCL-Comparatively newer,can be used for medium range of duration.
Safety profile under study

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