Purpose:
To introduce a technique to improve corneal symmetry and BSCVA (best spectacle corrected visual acuity) in the treatment of Keratoconus. Conductive Keratoplasty (CK) guided by intra-operative keratometry, is performed immediately before implanting Intacs for Keratoconus.
Anita Nevyas-Wallace, MDBala Cynwyd, Pennsylvania
Financial disclaimer: The author is a shareholder in Varitronics, Inc.
Combined CK and Intacs for Keratoconus:Combined CK and Intacs for Keratoconus:Improved Corneal Symmetry and Visual AcuityImproved Corneal Symmetry and Visual Acuity
Improving Corneal Symmetry & Visual Acuity in Keratoconus with Keratometry-Guided Conductive Keratoplasty Prior to Intrastromal Corneal Ring Implantation
MethodReport of 3 cases of keratoconus treated with 4 - 6 CK spots placed at the 9mm optical zone immediately before implantation of a single Intacs segment (Addition Technology, Des Plaines, IL) in the maximally elevated hemi-meridian. Pressing with a blunt instrument mimics the effect of corneal steepening and shrinkage from a CK spot. CK spot placement is determined by pressing on the cornea in different hemi-meridians and assessing which most circularizes the egg-shaped reflection of the “ring of lights” of the operative keratometer (Varitronics, Inc., Broomall, PA). Successive spots are placed (maximum six), until slight overcorrection is observed.
Ways CK Has Been Used in Keratoconus1. Previously, CK has been used to steepen
the flat meridian (Boxer Wachler1)
[place CK spots in [place CK spots in flatflat area] area]
More recently,
2. To shrink and “centralize” the cone (Hardten2) [place CK spots in [place CK spots in most elevated most elevated area] area]
3. The method described here shrinks and centralizes the cone under keratometric guidance
1. Personal communication2. Personal communication
Customizing CK Application Pattern
• Elevation Topography Elevation Topography – Crucial for identifying most
elevated hemi-meridian
• Operative Keratometry Operative Keratometry – Intraoperative feedback
Varitronics Operative Keratometer with Movable Fixation Device
Intraoperative Feedback is Key in CK for Keratoconus
Ring reflection assessed as blunt instrument presses different areas
Instrument pressure mimics the corneal steepening and shrinkage of CK
This guides placement of each CK spot
Technique For CK Before Intacs
1) Pachymetry: Verify > 500 μ at 9 mm o.z. of most elevated hemi-meridian
2) Mark 9 mm optical zone (o.z.)
3) Identify “point” of egg-shaped reflection
4) Determine where pressure with blunt instrument best circularizes the egg shape, then place CK spot
5) Repeat steps 3 and 4
Technique For CK Before Intacs
• Once point of egg is slightly flattened with CK (4 to 6 spots), then
• Make tunnels & Insert Intacs
3 Keratoconus Patients3 Keratoconus PatientsBR: 43yo woman with KC o.d. > o.s. MR BSCVA
Pre-op o.d. +2.75 -9.75 x 66° 20/40+
3½ mos post Intacs with CK +2.50 - 6.75 x 95° 20/30-2
8 mos post orig Intacs with CK 4½ mos post CK enhancement (add’l spots placed just inside Intacs segment)
+1.00 -2.25 x 68° 20/25Pt pleased w/improved UCVA, BSCVA
GJ: 71yo man with KC, cataract o.u. MR BSCVA UCVA
Pre-op o.d. +6.00 -3.50 x 180° 20/50- 20/200
4½ mos post Intacs w/CK3 mos post PEIOL
+1.00 - 2.50 x 83° 20/15- 20/40
CP: 58yo man with KC, cataract o.d. > o.s. MR BSCVA UCVA
Pre-op o.d. -4.50 -3.75 x 55° 20/40 CF
6 mos post Intacs w/CK 3½ mos post PEIOL (toric IOL)
pl - 2.25 x 73° 20/20- 20/40-
Pre-Intacs with CK
Post-op
Elevation difference map
Results All patients showed improvement in UCVA and BSCVA of
at least 2 lines (Snellen). Corneal symmetry on elevation corneal topography was
improved in all patients.
Post
Cone much flatter, less peripheral after CK with Intacs
GJ – o.d.
Pre-Op
Post-Op
Elevation maps Curvature maps
Cone much flatter, less peripheral after CK/IntacsCone much flatter, less peripheral after CK/Intacs
Pre-op 3 month 6 monthCP
Elevation maps
Curvature maps
Cone becomes flatter, less elevated, more centralCone becomes flatter, less elevated, more centralCone much flatter, less peripheral after CK/IntacsCone much flatter, less peripheral after CK/Intacs
Conclusion
Guided by operative keratometry and performed just before implantation of Intacs for keratoconus,
Conductive Keratoplasty flattens, shrinks and displaces centrally the cone
so that the Intacs segment may be placed in a more effective position
for improving corneal symmetry and for reducing regular and irregular astigmatism in keratoconus.
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