Techniques of cataract surgery

Techniques (ICCE)
Smith’s method
Arruga’s method
Erysiphakes
Cryo surgery
Chemical dissolution of zonular fibers
Smith’s technique
Smith used external pressure with muscle hook to mechanically break the inferior zonules
Expelled the lens through the limbal incision
The lens would "Tumble", I.e. the inferior pole would exit the eye before the superior pole
Arruga’s method
Toothless forceps (Arruga’s) used to grasp the lens capsule and then gently pulled from the eye using side-to-side motion that broke the zonules
Erysiphakes technique
Suction cup-like devices were used to remove the lens with traction
Cryo surgery
Cryprobe: Hollow metal-tipped probe, cooled by liquid nitrogen, that is touched to the lens surface
As the temperature of the probe tip falls below freezing, an ice ball forms and the lens adheres to it
This instrument forms an ice ball, fusing the lens capsule, cortex, and nucleus
Lessening the risk of capsular rupture as the cataract is removed
Chemical dissolution of zonular fibers
Enzyme alpha-chymotrypsin
The enzyme is irrigated into posterior chamber to dissolve the zonular fibers in order to facilitate ICCE surgery
Enhances the safety of ICCE by increasing the ease of lens removal
Extra capsular cataract extraction (ECCE)
Shift from ICCE to modern ECCE
To decrease the rate of potentially blinding:
Complications
To facilitate the placement of PC IOLs
By leaving the PC intact, the surgeon could decrease the risk of:
Vitreous loss and
Complications like RD, CME, and Bullous Keratopathy

Indications of ICCE
Operating microscopes not available
Unstable / luxated cataracts
Week zonular support
Advantages of ICCE
Cryoprobes
Capsular forceps
Erysiphakes
Allow this procedure
To be performed
Under most conditions

Vitreous complications:
In young patients PC is firmly adherent to anterior
hyaloid; attempted ICCE will usually result in vitreous loss
Intact vitreous face may opacify and ¯ vision
Adherence to corneal endothelium (corneal edema)
Adherence to iris (pupillary block glaucoma)
Broken vitreous face may incarcerate in the wound with vitreous traction causing:
RD
CME
Vitreous in AC causing open angle glaucoma
IOL implantation problematic since posterior capsular support missing
IOL choices include:
ACL /Sutured PC IOL (Iris fixation IOLs no longer available)
These significant disadvantages and risks led to loss of popularity of ICCE
Patient preparation
Pharmacologic pupillary dilation with topical mydriatic and cycloplegic agents to facilitate lens removal (iris retractors intraoperatively)
Anaesthesia



Procedure
Postoperative course
VA should be consistent with:
Refractive state of the eye
Clarity of the cornea
Clarity of the media
Visual potential of the retina and optic nerve
ECCE
ECCE involves removal of the nucleus and cortex through an opening in the anterior capsule (anterior capsulotomy), leaving the posterior capsule in place.

Advantages of ECCE surgery
Smaller incision
Less traumatic to corneal endothelium
Eliminates complications (short and long term) associated with vitreous adherent to:
Incision wound
Iris
Cornea



Contraindications (ECCE)
Zonular weakness
ECCE requires zonular integrity for selective removal of nucleus and cortical material
Therefore when zonular support appears insufficient to allow safe removal of the cataract through ECCE surgery, ICCE or Pars Plana Lensectomy should be considered
Instrumentation (ECCE)
A wide range of instruments is available for each step of ECCE:
Opening the anterior capsule
Dissecting and removing the nucleus
Removing the lens cortex
Polishing PC
Cystotome
Used for anterior capsulotomy (opening in the anterior of the lens)
Fashioned from 25 gauge needles by bending at its hub and beveled tip
Prefabricated cystotomes also commercially available
The needle tip is used to puncture and tear the anterior capsule
Irrigation and aspiration system coaxial, double-lumen blunt cannulas
One lumen irrigates BSS into the AC
Second lumen aspirates lens material out of the AC
Irrigation is gravity fed from a solution bottle
Fluid flow is regulated with adjustment of bottle height
The flow may be constant, or the surgeon can employ a foot control connected to A pinch valve
Lens nucleus
Removed by a variety of techniques, each
with its own set of instruments:
Lens expressor
Lens loop
Spoon, Vectis
Procedure ECCE
Pupillary dilation
Critical to the success of ECCE esp. phacoemulsification
Cycloplegic / mydriatic drops
NSAID (topical/oral) these agents help to maintain dialation during surgery






Nuclear expression
Manual
Whole (Lens loop, spoon, vectis, irrigation)
Fragmentation with forceps/nuclear splitter)
Ultrasonic fragmentation
Lens cortex aspiration
Syringe connected to cannula
Pump system controlled by foot switch
Posterior capsular polishing
Abrasive tipped irrigation cannula / low vacuum clean using low aspiration remove epithelial and cortical particles from the capsular surface
IOL implantation
AC filled with viscoelastic / BBS / air
Viscoelastic most reliable AC maintainer
It also protects corneal endothelial
IOL inserted in the ciliary sulcus / capsular bag
Sulcus fixation:
Requires greater IOL diameter (>12.5 mm)
Large diameter optic (6 mm)
More forgiving in case of postoperative decentration
Bag fixation:
IOL diameter <12.5 mm
Optic diameter 5.00 mm
Wound suturing
10/0 Nylon
Proper suture tension ¯ postoperative Astigmatism
Loose sutures – Against-the-rule Astigmatism
Tight sutures – With-the rule Astigmatism
Postoperative course ECCE
As with ICCE, VA on the first postoperative day should be consistent with:
Refractive state of the eye
Clarity of the cornea
Clarity of the media
Visual potential of the retina and optic nerve
Postoperative course ECCE
Lid: Mild eye lid edema and erythema may occur
Conjunctiva: May be injected and boggy
Cornea: Should be clear and free of striate / edema
AC: Should be of normal depth and mild cellular
reaction typical


Phacoemulsification
Phacoemulsification is an ECCE technique that differs from "standard ECCE with nuclear expression" by the:
Size of incision required
Method of nucleus removal
This technique uses ultrasonically driven needle (phaco tip) to fragment the nucleus and aspirate the lens substance through a needle port









Complications of cataract surgery
Complications are varies in time and scope
Intraoperative
Immediate postoperative
Late postoperative
Therefore it is necessary to observe the
postoperative patients at periodic intervals
Table IX-1
Major postoperative complications of cataract
Surgery
______________________________________
Endophthalmitis
Sterile
Infectious
Corneal edema
Detached Descemet’s membrane
Mechanical trauma
Vitreo-endothelial touch
IOL-endothelial touch
Toxic solutions

Shallow or flat AC
Intraoperative
Inadequate infusion of BSS
Leakage over sized wound
External pressure on the globe
Positive vitreous pressure more common in:
Obese
Bull necked pts.
COPD
Anxious Pts. Who perform valsalva maneuver
Supachoroidal haemorrhage or effusion
Shallow or flat AC
Management
Raise infusion bottle
Place suture across the wound to ¯ its size
External pressure: Readjust surgical drapes or eye lid speculum
Positive vitreous pressure:
I/V manitol ¯ the ­ positive pressure and
Allow the case to continue uneventfully
Suprachoroidal hemorrhage or effusion:
Check red reflex
Examine fundus with indirect ophthalmoscope to confirm diagnosis
Shallow or flat AC
Postoperative shallow AC
Postoperative shallow AC ® opposition of iris to angle ® PAS ® chronic ACG. Irido-vitreal (ICCE) of irido-capsular (ECCE) synechiae ® pupillary block. Corneal contact with vitreous / IOL ® endothelial cell loss ® chronic corneal edema
Shallow or flat AC
Causes
Wound leak
Choroidal detachment
Pupillary block
Ciliary block
Suprachoroidal hemorrhage
Cases associated with ocular hypotension are 2ndry to
wound leakage / choroidal detachment. Slow or
intermittent wound leaks may coexist with formed AC

Shallow or flat AC
Seidel Test:
To detect an area of wound leakage. Instill one drop of 2% fluorescein and examine the incision with cobalt blue filter on the SL. Aqueous dilution of fluorescein at the site of leakage will produce contrasting area of green stain. Occasionally aqueous flow is so slight that gentle pressure on the globe is necessary to confirm the site of leakage.
Management (Postoperative shallow AC)
Several Options
Cycloplegics and pressure patching
CAI and topical beta blockers: ¯ Aqueous flow through the woung
Corticosteroid avoidence: Enhance local wound reaction to faciliatte spontaneous closure
Therapeutic contact lens help in opposing wound edges and ¯ aqueous flow through the wound
Tissue adhesive may seal the wound
These measures are appropriate for minor wound leaks
Many patients develop associated ciliochoroidal
detachment which resaolves spontaneously after
wound closure
Corneal edema
Factors:
­ IOP
Endothelial cell damage
Edema in the immediate postoperative period
Incidence is increased in preexisting endothelial Dysfunction
Causes:
Mechanical trauma
Prolonged intraocular irrigation
Inflammmation
Increased IOP
Acute endothelial decompensation with increase in corneal
thickness resolves in 4 – 6 weeks
Corneal edema persisting after 3 months will usually not clear and
may require penetrating keratoplasty















Hyphaema
Early / Late
Early: Immediate postoperative period
Origin: Incision / Iris
Mild resolves spontaneously
Mixed with blood / viscoelastic – resolution longer
Late: Months / years after surgery
Origin: wound vascularization / erosion of vascular tissue by lens implant


Retinal light toxicity
Prolonged exposure to the light of operative microscope can result in burn of RPE
The problem especially serious when filtering effects of natural lens (cataract) are removed, exposing RPE to unfiltered blue light and near-UV radiation
Foveal burn: ¯ VA
Extrafoveal: Paracentral scotoma
Endophthalmitis
Acute
Chronic (indolent): Organisms of lower pathgenicity
Sterile (non-infectious)
Acute endophthalmitis
Presentation:
Ocular pain
¯ VA
Ciliary injection
Chemosis
Hypopyon




Cystoid macular edema (CME)
CME (Irvine-gass syndrome): common cause of ¯ VA after both complicated and uncomplicated cataract surgery
Pathogeneis not known
The final common pathway appears to be ­ perifoveal capillary permeability
Associated factors:
Inflammation and release of PGs
Vitreo-macular traction
Hypotony (Transient/prolonged)


Chronic uveitis
Low grade bacterial pathogens (e.g. propioni-bacterium acne, staphlococcus epidermidis)
Patients may have unremarkabel postoperative course
Lacks the classic findings of acute endophthalmitis
Wks / Months later develop chronic uveitis that is variably responsive to steroids
Granulomatous KPs and Less commonly with hypopyon
Localized focus / sequestrum of infection may be observed (lens capsule)
















Suture induced astigmatism
Tight sutures ® post-operative astigmatism,
Steepens the cornea in the
direction of sutures
Removing sutures 6 – 8 wks postoperatively may alleviate astigmatism
Wound leak – significant against the rule astigmatism
Secondary intra-ocular infection- entry of organisms into the eye through suture tract

Complications of IOL implantation
Decentration and dislocation
Uveitis – glaucoma – hyphaema (UGH) syndrome
Corneal edema and pseudo-phakic bullous keratopathy
Wrong power IOL