1. Single Inferior Intac Insertion for Inferior Keratoconus
James Genge MD
Vision Eye Institute Southline
Sydney Australia
No Financial Interest to disclose

2. Purpose
To investigate the effectiveness of a single inferior Intac segment for inferior keratoconus
Rationale was to harness the flattening effect of the Intac segment by placement in the area of maximal steepness noted on corneal topography
Entrance incision positioned to allow adequate distance from Intac segment to minimise extrusion risk.

3. Study } Asymmetry > 4 D, select 0.45mm segment Indications
Demographics
N = 46
Average age 35
65% Male 35% Female
0.45mm Intac 76%
0.40mm Intac 24%
Indications
K’s < 55
No central scarring
Inferior corneal thickness > 430
Post op follow up for 6 months assessing:
UCVA
BSCA
Change in keratometry
Change in Inferior: Superior ratio index
Complications
} Asymmetry > 4 D, select 0.45mm segment

4. Method Corneal center marked
Intralase created channel at 400 µm, mm width
Intacs clear curved 150º PMMA segment, 0.40, 0.45mm
Intacs position orientated to maximally steep corneal curvature, entrance incision 13 degrees away
Single segment inferiorly

5. Complications Patients counseled re unpredictable refractive result
Fluctuating vision, stabilises at 3 months
1 Patient: subincisional Intac migration; repositioned
2 Patients: glare / night vision difficulties
No Infection / neovascularisation / melt

6. Results Variable response, depending on pre-op keratoconic status
Mild cones: significant improvement
Steep cones, high myopia: less effective
Improvement continues over 3 months +
If removed: returns to previous keratometry
Case example:
UCVA = 6/6
UCVA = 6 /20

7. Results: Refractive Comparison Data
Sphere
Cylinder SE
Preop
-0.75Ds
-2.85Ds
-2.16Ds
3 Months
-0.65Ds
-1.96Ds
* P = 0.015
-1.16Ds
* P = 0.008
6 Months
-0.30Ds
-1.99Ds
-1.30Ds
* P = 0.018

8. Results: Keratometry and Symmetry Comparison Data
Cylinder
Average K’s
I-S Ratio
Preop
3.14D
46.22D
8.62
6 Months
2.74D
44.49D
* P = 0.000
3.32

9. Results: UCVA

10. Results: BCVA

11. Results: Lines of BCVA Gained or Lost at 3 Months

12. Summary
Reversible, adjustable treatment for mild to moderate keratoconus
Single inferior Intac placed at maximal corneal steepness determined by topography effective for inferior keratoconus
Alternatives:
Two Intacs Inserted
Intacs SK & Kerarings
more effective due to smaller Optical Zone
may increase glare
Corneal Transplantation if ineffective
Adjunctive Cross linking / PRK to enhance effect