Current overview of Microkeratomes

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Current overview of Microkeratomes

• Dr Kareeshma Wadia
• DNB, FNN
• Cataract, Cornea and Refractive Surgeon
• Director- Jehan Eye Clinic, Mumbai

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NO FINANCIAL INTERESTS
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PRINCIPLE

• High-precision oscillating-blade systems
• Docks to a suction ring
• Creates a lamellar corneal flap while the cornea
  is held under high pressure.

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TYPICAL COMPONENTS OF A MODERN MICROKERATOME
SYSTEM

• Console
• Motor
• Microkeratome head
• Applanator lenses
• Vacuum fixation
• Flap stop ring , which limits the microkeratome
  head through the fixation ring
• Foot switch

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CONSOLE
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MOTOR AND MICROKERATOME HEAD

• Motor of keratome initiates
• Forward movement of head
• Oscillation of blade for the cut

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MODALITIES OF MICROKERATOME PASS

• Rotative/Pivoting flap creation
• less space needed,
• hinge placement variable
• - flap is thick thin thick
• due to the upward movement
• of the suction ring during the cut
• Hansatome, Carriazo

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MODALITIES OF MICROKERATOME PASS

• Linear flap creation
• intraop visibility during flap creation,
• planar flap profile
• - fixed hinge position
• Amadeus, SBK

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TYPE OF HEAD- Vertical / horizontal
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SUCTION RING

• Suction ring will induce rise in IOP
• First step? choosing right size of suction ring
• Suction ring diameter determines
• How much of the cornea will protrude into the
  microkeratome
• primary determinant of flap diameter.
• Steep Cornea ? more tissue will protrude
• Flat Cornea ? less tissue will protrude

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ALWAYS FOLLOW NOMOGRAM
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VACUUM SETTING

• Achieving and maintaining adequate vacuum during
  microkeratome pass is critical to producing
  accurate flap.
• IOP at least 65mmHg for most microkeratomes
• Suction system and IOP should always be checked
  prior to every procedure
• Lower pressures can produce thinner cuts and
  irregular flaps
• Higher pressures can lead to chemosis, s/c
  hemorrhages, optic nerve injury

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PLACING THE SUCTION RING

• The LASIK pneumatic suction ring is placed on the
  eye.
• With a suction pressure greater than 65 mm Hg,
  the instrument fixates the globe at the limbus
  and provides a dovetail track for the
  microkeratome.

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THE NEED FOR TRANSIENT HIGH IOP

• IOP gt65 mm Hg
• Barraquer tonometer, a conical lens with a flat
  undersurface marked with a circle, and convex
  upper surface that acts as a magnifier.
• Dry cornea
• Gives uniform microkeratome section

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MICROKERATOME PRACTICAL TIPS

• Counsel well before taking the patient
• Briefly explain the procedure -
• That it will take 5-7minutes per eye
• You will feel little pressure on eye
• For few seconds you wont see the lights
• Not to squeeze the eyes
• Not to move the eyes
• You will hear some noises of Keratome and the
  laser machine

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MICROKERATOME PRACTICAL TIPS

• Blade assembly and inspection
• Check suction
• Always do a trial pass before actual procedure
• Listen to sound of blade oscillation

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MICROKERATOME PRACTICAL TIPS

• Always do marking on the cornea before keratome
  pass
• Advantages of marking
• Proper alignment of the flap post ablation
• In case of free flap marking will help you to
  place the flap in its natural position
• Also helps in identifying the epithelium and
  stromal side of free flap

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ADVANTAGES OF MECHANICAL MICROKERATOMES

• Proven history
• Lower cost
• More efficient surgical flow lt30 secs
• Ability to create flaps in anterior stromal
  opacity/scar
• Less inflammation

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• Laser in situ keratomileusis was performed using
  the Moria microkeratome with the
• One Use-Plus SBK,
• M2 90
• M2 110 head.

The SBK head demonstrated the most accurate flap
thickness, followed by the M2 90 head and the
110 head.
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1- No difference in visual acuity 2- Dry eye
associated with MK and DLK with femto
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• Comparison between
• Amadeus
• Carriazo
• Moria M2
• SBK
• Nidek
• Hansatome

• CONCLUSIONS
• Variability between all 6 models
• Device labelling did NOT represent flap thickness
  achieved
• Thinner corneas had thinner flaps and similar for
  thicker corneas
• 1st cut (1st eye) had a thicker flap in B/L
  procedures

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More flap predictability in Femto
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Thank you

• Dr Kareeshma Wadia
• jehaneyeclinic_at_gmail.com