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.