Technical Information

During cataract surgery, the natural lens is removed and an artificial intraocular lens is inserted.  Viscoelastics are used extensively during the procedure and serve many purposes.

The most common methods of lens removal are extracapsular extraction and phacoemulsification.  The specific purposes of the viscoelastic during each of these procedures are listed below.

In Extracapsular Extraction

• Fill, maintain and cushion the anterior chamber
• Coat and protect endothelial cells
• Smooth out anterior capsule
• Prevent or reposition iris prolapse
• Push back choroidal hemorrhage 
• Hydraulic separation of nucleus and cortex 
• Keep pupil dilated due to increased IOP 
• Tamponade bleeding vessels  
• Restore integrity of globe when vitreous is lost 
• With mature cataract, fill and expand capsule 
• Reposition detached Descement’s membrane 
• Ease passage of limbus sutures 

In Phacoemulsification

• Coat corneal endothelium 

• Cushion introduction of various instruments 
• Push iris or vitreous back
• Maintain a deep chamber
• Help rotate the nucleus within the capsule bag
• Plug hole in posterior capsule temporarily

Viscoelastics are also important during lens implantation.  The main consideration in selecting a viscoelastic for lens implantation is to maintain the anterior chamber depth and corneal dome.  Thus surgeons look for a viscoelastic solution that is relatively cohesive in order to maintain the chamber while at the same time protecting the corneal endothelium during lens insertion.  However, surgeons are also concerned with how difficult it is to move the lens and instruments through the viscoelastic, so they look for high pseudoplasticity to prevent drag. 

Common use of viscoelastic solutions in lens insertion:

• Expand the capsular bag for lens insertion
• Expand ciliary sulcus for insertion
• Cushion anterior chamber angle for anterior lens insertion
• Coat IOL
• Coat and cushion corneal endothelium
• Create adequate space for insertion of instruments and implants
• Tamponade opening through which air, aqueous, or vitreous may be lost
• Push back vitreous or anterior hyaloid membrane during IOL implantation
• Tamponade break in posterior capsule for placement of implant