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