Comparison of single-segment and double-segment Intacs® insertion with

femtosecond laser for keratoconus

Tiep KHUC, Marc DOAT, Jean-Louis BOURGES, Nicolas ALFONSI, Jean-Marc LEGEAIS, Gilles

RENARDHôtel-Dieu Hospital, Paris, France

Authors have no financial interest

Purpose

To evaluate the efficacy of single-segment Intacs® using the femtosecond laser (IntraLase®, AMO) for insertion and compare with double-segment Intacs® in subjects with keratoconus

Methods (1/2)

• Setting: Hôtel-Dieu, Paris, France

• Prospective study

• 66 eyes of 59 patients classified into two groups- single-segment group: 38 eyes, 35 patients- double-segment group: 28 eyes, 26 patients

• Both groups matched by t test

Methods (2/2)• Implantation procedure

Femtosecond IntraLase® FS 2 laser (60 kHz) (IntraLase Corp.)

• Parameters- dissection’s depth in the cornea was 80% of the central pachymetry (300 – 400 µ)- channel dissection size: 6.6 x 7.6 mm

• Main outcome measure: improvement of visual acuity, refractive error, K values

• Follow-up: 6 months

• Single or double-segment Intacs® implanted according to keratoconus asymetry and spherical equivalent (SE)

Global results

Variable Preoperative Postoperative

UCVA (logMAR) 1.13±0.46 (0.5/10) 0.57±0.45 (3/10)

BSCVA (logMAR) 0.54±0.33 (3/10) 0.34±0.30 (5/10)

Sphere (D) -3.37±4.05 -1.62±2.76

Cylinder (D) -3.90±2.09 -2.55±1.80

SE (D) -5.41±4.35 -2.70±2.99

Steep K (D) 57.4±7.3 54.0±6.9

Flat K (D) 46.4±7.1 43.4±5.0

Average K (D) 51.9±6.5 48.7±5.5

p < 0.05 for each variable.

Single-segment results

Variable Preoperative Postoperative

UCVA (logMAR) 1.01±0.49 (1/10) 0.40±0.34 (4/10)

BSCVA (logMAR) 0.45±0.31 (4/10) 0.24±0.22 (6/10)

Sphere (D) -2.53±3.93 -1.34±2.56

Cylinder (D) -4.14±2.16 -1.93±2.47

SE (D) -4.59±4.18 -2.30±2.80

Steep K (D) 56.1±6.8 52.7±6.0

Flat K (D) 43.7±4.3 42.6±3.5

Average K (D) 49.9±4.8 47.7±4.2

p < 0.05 for each variable.

Improvement of UCVA for 34 eyes (89%).

Double-segment results

Variable Preoperative Postoperative

UCVA (logMAR) 1.32±0.32 (0.5/10) 0.82±0.48 (1.6/10)

BSCVA (logMAR) 0.69±0.32 (2/10) 0.49±0.34 (3/10)

Sphere (D) -4.95±3.92 -2.25±3.16

Cylinder (D) -3.44±1.92 -3.96±1.70

SE (D) -7.13±4.31 -3.49±3.33

Steep K (D) 59.6±7.8 56.4±7.8

Flat K (D) 50.4±8.6 44.8±6.9

Average K (D) 55.0±7.8 50.6±7.0

p < 0.05 for each variable, except cylinder (p=0.18).

Improvement of UCVA for 21 eyes (75%).

Comparison double vs single-segment

Improvement of visual acuity after 6 months (double-segment group)

3 41

5

15

47

57

5

0

5

10

15

20

loss of lines 0 line 1-2 lines 3-4 lines > 4 lines

Preoperative-postoperative changes

Nu

mb

er o

f eye

s

UCVA BSCVA

Only 1 eye experienced loss of BSCVA in the single-segment group, versus 5 eyes in the double-segment group.

Improvement of visual acuity after 6 months (single-segment group)

04 3

7

24

1

8

1311

5

0

5

10

15

20

25

30

loss of lines 0 line 1-2 lines 3-4 lines > 4 lines

Preoperative-postoperative changes

Nu

mb

er o

f eye

s

UCVA BSCVA

Complications

• No peroperative complication

• 8 Intacs® (7.6%) were removed from 5 eyes because of partial extrusion

Discussion (1/2)

• Safe and efficient; improvement of UCVA+++

• Trend towards improved outcomes with single-segment Intacs® (more important reshaping of the cornea)

• Results consistent with existent data (Sharma, 2005)

• Cases of loss of vision may be attributed to an induced irregular astigmatism

Discussion (2/2)

Double-segment (preop/postop/differential)

Single-segment (preop/postop/differential)

Superior and inferior flattening

Superior steepening

Inferior flattening

Conclusion• Intacs® implantation using IntraLase® FS 2 was safe and effective

for treating keratoconus

• Better results were achieved with single-segment Intacs®

• Colin J, Cochener B, Savary G, Malet F, Holmes-Higgin D. INTACS inserts for treating keratoconus: one-year results. Ophthalmology 2001;108:1409-1414.

• Siganos CS, Kymionis GD, Kartakis N, Theodorakis MA, Astyrakakis N, Pallikaris IG. Management of keratoconus with Intacs. Am J Ophthalmol 2003;135:64-70.

• Alio JL, Artola A, Hassanein A, Haroun H, Galal A. One or 2 Intacs segments for the correction of keratoconus. J Cataract Refract Surg 2005;31:943-953.

• Sharma M, Boxer Wachler BS. Comparison of single-segment and double-segment Intacs for keratoconus and post-LASIK ectasia. Am J Ophthalmol 2006;141:891-895.

• Ertan A, Kamburoglu G. Intacs implantation using a femtosecond laser for management of keratoconus: Comparison of 306 cases in different stages. J Cataract Refract Surg 2008;34:1521-1526.