single inferior intac insertion for inferior keratoconus
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Single Inferior Intac Single Inferior Intac Insertion for Inferior Insertion for Inferior
KeratoconusKeratoconus
James Genge MDJames Genge MD
Vision Eye Institute SouthlineVision Eye Institute Southline
Sydney AustraliaSydney Australia
No Financial Interest to disclose
PurposePurpose• 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.
StudyStudy• 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
MethodMethod• Corneal center marked
• Intralase created channel at
400 µm, 6.6 - 7.5 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
ComplicationsComplications
• 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
ResultsResults• 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
UCVA = 6 /20 UCVA = 6/6
Case example:
Results: Refractive Comparison Results: Refractive Comparison DataData
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
Results: Keratometry and Results: Keratometry and Symmetry Comparison DataSymmetry 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
* P = 0.000
Results: UCVAResults: UCVA
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
6/66/7.5
6/9 6/12 6/15 6/18 6/21 6/24 6/30 6/45 6/606/120
Preop UCVA3 Months UCVA6 Months UCVA
Results: BCVAResults: BCVA
0.0%
10.0%
20.0%
30.0%
40.0%
50.0%
60.0%
70.0%
80.0%
90.0%
100.0%
6/6 6/7.5 6/9 6/12 6/15 6/18 6/21 6/24 6/30 6/45 6/60
Preop BCVA3 Months BCVA6 Months BCVA
Results: Lines of BCVA Gained Results: Lines of BCVA Gained or Lost at 3 Monthsor Lost at 3 Months
0.0% 0.0%
9.1%
36.4%
21.2%
15.2%18.1%
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
> 3 lines lost 2 lines lost 1 line lost No change 1 line gained 2 lines gained >3 linesgained
% of Patients
SummarySummary• 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
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