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WOUND CLOSURE(VECTOR ANALYSIS)
ECCE
• VERTICALLY APPLIED IOP AND TISSUE FORCES IN OPPOSITE DIRECTION
PHACO
• HORIZONTALLY APPLIED SUTURE FORCE
DYNAMICS OFSUTURELESS
CATARACT INCISIONS
THEORY
• Corneal flap mechanismTHEORY
• Square incisional geometry
SQUARE INCISIONAL GEOMETRY
EXTERNAL INCISIONINTERNAL INCISIONTUNNEL SIZE
astigmatically neutral funnel •
corneal astigmatism is directly proportional to the cube of the length of the incisioninversely related to the distance from the limbus
SELF-SEALING WOUND DEPENDS ONThe architecture of the woundDelicate handling of tissue
edgesAdequate intraocular pressure
PHACO INCISIONGOALS
INTRAOPERATIVELYPOSTOPERATIVELY
INTRAOPERATIVE
Allow Easy Entry Of The Phaco NeedleAllow Ease Of Mobility Of The Phaco NeedleMinimize Incision LeakPrevent Incision Burn.
POSTOPERATIVE
Self SealedAstigmatically NeutralBoth In Short Term And Longterm
vital statistics of a phaco incision
1. Site (limbal or …)2. Placement (time of incision!)3. Style(mood of the incision!)4. The length of the external incision 5. Length of the sclerocorneal tunnel 6. Depth of tunnel dissection 7. Size of initial opening for phacoemulsification
8 . Size of incision for IOL insertion9. Paracentesis opening
INSTRUMENTS REQUIRED FOR THE PHACO INCISIONS(sclera tunnel)
A 15° freehand/preset depth (300 micronA 2.0 mm broad crescent blade A suitable breadth keratomewith a 90 degrees
angle at the tip (bevel up)A 0.6 to 1.0 mm broad blade for the
paracentesis A blunt tipped extender blade (bevel down)A caliper
TECHNIQUE OF MAKING A PHACO (Scleral Tunnel)INCISION
Peritomy and cauteryGroovingTunnel dissectionStab incisions and AC viscoinjectionAC entry
clear corneal incision (advantages)
• Well suited for topical anesthesia• lesser risk of bleeding• better accessibility• better red reflex• eliminates the conjunctival incision• minimal or no effect on astigmatism
disadvantages of clear corneal incision
• technical difficulty • lack of forehead support• need to enlarge for use of nonfoldable IOLs• difficulty in converting to a ECCE• potential for greater endothelial cell loss• .possible corneal thermal burns • .higher incidence of endophthalmitis in some
studies
Proposed incision for begginers(changing ECCE to phaco)
• limbal groove• Straight or • Parallel to limbus• Biplanar• Slightly wider than phaco tip
PARACENTESIS OPENING
required for bimanual techniquesUsually on the left side (30-90 degree) 0.6 to 1.0 mm in breadthsimple stab or shelved
Clear Cornea Incision
With initial partial thickness vertical incision
Without an initial incision
ASTIGMATIC INDUCERS
1. Longer incision.2. Corneal incision.3. Limbus parallel incision. 4. Uniplanar incision. 5. Sutured incision
The caliper is set at 2.8 mm.
A light indentation on the peripheral cornealsurface is created with the pointed ends 0f the caliper.
A 150-300-um-depth groove is created
A paracentesis incision is created with thediamond blade fully extended
An oblique entry is created as the blade notonly driven through the corneal stroma to Descemet 'slevel. but also slices to the surgeon 's left. Notice thecompression of tissue being created because ofthe
relatively dull blade
Descemet's level is entered 1.75 mm fromthe epithelial level as the blade is swept to
the left.