Clinical Outcomes of Intrastromal Corneal

Ring Implantation using Femtosecond

Laser

Maria Clara Arbelaez, MDMaria Clara Arbelaez, MD

No financial interestNo financial interest

Purpose To report the results of Intrastromal corneal

rings segments ( Keraring-Mediphacos) implantation using a LDV (Ziemer) femtosecond Laser on:

Visual Acuity (UCVA and BCVA) Refractive Outcome Topographic findings ( keratrom

scout) Corneal wavefront (keratrom scout) Ocular wavefront ( schwind

aberrometer) Anterior and posterior elevation

(Pentacam and Galilei)

Methods Improvement in vision is based on

the Visual Acuity Conversion Chart as recommended by Holladay JT

Visual acuity measurements. J Cataract Refract Surg 2004;30:287-290

Methods Femto( LDV-Ziemer) with a Hand piece with 450 µm focal depth, following

the same principles for flap creation (suction ring, applanation,

intrashield), with a top view camera to visualize the trajectory , control

shifted trajectory at 25 microns increments and possibility of tunnel

customization in wide and arch

Intracorneal rings Si5 with internal diameter of 5mm ( Kerarings –

Mediphacos), following the manufacture recommended nomogram; using rings of

210, 160,150,120 and 90 degrees and 150, 200,250,300 and 350 microns, on

symmetric and asymmetrical placements.

PRE-OPERATIVE DATA, N=70

Sphere -16 to +2.25

Mean -3.68 SD 3.83

Cylinder -6.00 to -0.25

Mean -3.57 SD1.54

UCVA 0.01 ( CF) to 0.60 ( 20/32)

Mean 0.09 ( 20/250) SD 0.12

BCVA 0.15( 20/125) to 1.0 ( 20/20)

Mean 0.52 (20/40) SD 0.20

K average 41.2D to 60.18 D

Mean 48.29D SD 4.48

K apex 38.79D to 75.25D

Mean 49.61 D SD 7.38

6 MONTHS POSTOPERATIVE, N=60

Sphere -9.25 to +3.25

Mean -1.53 SD 2.17, P=0.0006

Cylinder -5.75 to -0.25

Mean -2.26 SD 1.33

UCVA 0.05 (20/400) to 0.9 ( 20/25)

Mean 0.42 (20/50) SD 0.20

BCVA 0.2 ( 20/100) to 1.0 (20/20)

Mean 0.62( 20/30) SD 0.21

K average 35.90 D to 57.51D

Mean 45.64D SD 3.57, P=0.0004

K apex 34.02D to 73.49D

Mean 47.77D SD 6.90,P=0.04

MethodsPOPULATION 70 CASES OF KERATOCONUS, AGE RANGE: 16-44, MEAN : 26.41

1 YEAR POST-OPERATIVE N=19

Sphere -7.00 to +1.75

Mean -1.91 SD 2.38, P=0.016

Cylinder -5.50 to -0.25

Mean -2.14SD 1.25 ,P=0.002

UCVA 0.15 (20/125) to 1.0 ( 20/20)

Mean 0.41 (20/50) SD 0.24

BCVA 0.25 ( 20/80) to 1.0 (20/20)

Mean 0.66( 20/30) SD 0.23

K average 40.40D to 56.20D

Mean 45.94 SD 4.22, P=0.001

K apex 38.36D to 74.62D

Mean 47.83D SD 8.75

MEAN CHANGE IN UCVA

CHANGE IN UCVA FROM THE PRE-OPERATIVE TO

6 MONTHS (N=60)

CHANGE IN UCVA FROM THE PRE-OPERATIVE TO

1 YEAR (N=19)

MEAN CHANGE IN BCVA

CHANGE IN BCVA FROM THE PRE-OPERATIVE TO 6 MONTHS (N=60)

CHANGE IN BCVA FROM THE PRE-OPERATIVE TO 1 YEAR (N=19)

There was a statistically significant reduction in the mean manifest sphere from pre-operative value of -3.68 D to –

1.40 D at 3 months post-operative (p=0.001), to -1.53 at 6 months post-operative (p=0006), to -1.91 D at 1year post-

operative, p=0.016

CHANGE IN MEAN MANIFEST SPHERE FROM PRE-OPERATIVE TO 3 MONTHS , 6 MONTHS

AND 1 YEAR

CHANGE IN MEAN MANIFEST CYLINDER FROM PRE-OPERATIVE TO 3 MONTHS , 6 MONTHS AND 1 YEAR

The mean manifest cylinder changed from a pre-operative value of -3.57 D to -2.31 D at 3 months post-

operative, p=0.0004, to -2.26D at 6months post-operative, and to -2.14D at 1 year p=0.002

There was a significant reduction in K average from a pre-operative value of

48.29D to 45.68 at 3 months post-operative, p=0.02, to 45.64D p=0.0004 at 6 months post-operative and 45.94 D at 1

year

TOPOGRAPHIC MEASURED CHANGE IN K AVERAGE AT 3 MONTHS, 6 MONTHS AND 1 YEAR

TOPOGRAPHIC MEASURED CHANGE IN K MAX AT THE TOPOGRAPHIC MEASURED CHANGE IN K MAX AT THE APEX AT 3 MONTHS, 6 MONTHS AND 1 YEARAPEX AT 3 MONTHS, 6 MONTHS AND 1 YEAR

There was a significant reduction in K max from a pre-operative value of 49.61D

to 47.47 D at 3 months post-operative, p=0.01, to 47.77 D at 6 months post-operative, p=0.04 and 47.83 at 1 year

post-operative

There was a significant reduction in the anterior elevation at the thinnest location from a pre-operative value of 28.17µm to 10.45 µm at 3

months post-operative, P=0.0002, to 13.14 µm at 6months and 14.61 µm at 1 year, p=0.03.

Significant difference was also found in the anterior elevation at the apex from pre-operative

value of 16.74 µm to 7.77 µm at 3 months, p=0.0003, to 8.36 µm at 6months, p=0.001, and

9.22 µm at 1 year, p=0.008

CHANGE IN ANTERIOR ELEVATION MEASURED BY THE OCULUS PENTACAM AT 3 MONTHS, 6 MONTHS

AND 1 YEAR

There was a significant reduction in the posterior elevation at the thinnest location from a pre-operative value of 48.36 µm to

33.20 µm at 3 months post-operative, p=0.0002, to 36.72 at 6months, p=0.04 and 37.89 um at 1 year, p=0.06. No significant

difference was found in the posterior elevation at the apex from pre-operative value of 26.97

µm to 11.67 µm at 1 year, p>0.05

CHANGE IN POSTERIOR ELEVATION MEASURED BY THE OCULUS PENTACAM AT 3 MONTHS, 6 MONTHS

AND 1 YEAR

 PRE-OP

N=70

3 MONTHS N=45

6 MONTHS N=60

1 YEAR N=19

COMA 3,-1 p=0.0003 -1.91 -0.83 -1.03 -0.93

COMA 3,1 p=0.01 0.155 0.127 0.101 0.014

SPHERICAL 4,0 -0.16 -0.26 -0.26 -0.26

TREFOIL 3,-3 0.29 0.20 0.24 0.03

TREFOIL 3,3 0.05 0.06 0.04 0.12

RMS p=0.003 2.67 2.17 2.26 2.08

 PRE-OP

N=703 MONTHS

N=456 MONTHS

N=601 YEAR

N=19

COMA 3,-1 p=0.01 -0.72 -0.29 -0.26 -0.24

COMA 3,1 0.00 -0.07 -0.03 0.09

SPHERICAL 4,0 -0.03 -0.14 -0.10 -0.11

TREFOIL 3,-3 p=0.03 -0.04 0.09 0.10 0.08

TREFOIL 3,3 -0.01 -0.03 0.02 -0.05

RMS 1.26 1.11 1.04 1.11

There was a significant reduction in coma 3,-1 (P=0.01) and Trefoil 3,3- (p=0.03) from pre-operativepre-operative

value to 1 year post-operative

OCULAR WAVEFRONT ANALYSIS: COMPARISON BETWEEN PREOPERATIVE VALUE TO

3 MONTHS, 6 MONTHS AND 1 YEAR POST-OPERATIVE

There was a significant reduction in coma 3,-1 (P=0.0003) , coma 3,1( p=0.01) and RMS (p=0.003) from

pre-operativepre-operative value to 1 year post-operative

CORNEAL WAVEFRONT ANALYSIS: COMPARISON BETWEEN PREOPERATIVE VALUE TO

3 MONTHS, 6 MONTHS AND 1 YEAR POST-OPERATIVE

Conclusion 98.33 % gain lines on UCVA at 6 months ( n=60 ) , 100 % improved UCVA at 1 year (n=19)

63.33% improved lines of BCVA at 6 months ( n=60 ), 57.9% gain lines at 1 year (n=19)

There was a statistically significant reduction in the mean manifest sphere from pre-operative value of -3.68 D to –1.40 D at 3 months post-operative (n=45) (p=0.001), to -1.53 at 6 months post-operative (n=60) (p=0006), to -1.91 D at 1year post-operative (n=19)(p=0.016)

The mean manifest cylinder changed from a pre-operative value of -3.57 D to -2.31 D at 3 months post-operative, p=0.0004, to -2.26D at 6months post-operative, and to -2.14D at 1 year p=0.002

There was a statistically significant reduction in the mean manifest sphere from pre-operative value of -3.68 D to –1.40 D at 3 months post-operative (p=0.001), to -1.53 at 6 months post-operative (p=0006), to -1.91 D at 1year post-operative, p=0.016

There was a significant reduction in K max from a pre-operative value of 49.61D to 47.47 D at 3 months post-operative, p=0.01, to 47.77 D at 6 months post-operative, p=0.04 and 47.83 at 1 year post-operative

There was a significant reduction in the anterior elevation at the thinnest location from a pre-operative value of 28.17µm to 10.45 µm at 3 months post-operative, P=0.0002, to 13.14 µm at 6months and 14.61 µm at 1 year, p=0.03.

Significant difference was also found in the anterior elevation at the apex from pre-operative value of 16.74 µm to 7.77 µm at 3 months, p=0.0003, to 8.36 µm at 6months, p=0.001, and 9.22 µm at 1 year, p=0.008

There was a significant reduction in the posterior elevation at the thinnest location from a pre-operative value of 48.36 µm to 33.20 µm at 3 months post-operative, p=0.0002, to 36.72 at 6months, p=0.04 and 37.89 um at 1 year, p=0.06.

No significant difference was found in the posterior elevation at the apex from pre-operative value of 26.97 µm to 11.67 µm at 1 year, p>0.05

Corneal wavefront aberrations: There was a significant reduction in the coma 3,-1 (P=0.0003) , coma 3,1( p=0.01) and RMS (p=0.003) from pre-operativepre-operative value to 1 year post-operative

Ocular wavefront aberrations: There was a significant reduction in coma 3,-1 (P=0.01) and Trefoil 3,3- (p=0.03) from pre-pre-operativeoperative value to 1 year post-operative

CalculationType I – II-0,25 sphere -5.50 cy l70Ring 160/250Axis 160Depth: 390 microns

3 Months Pre vs Pop3 Months Pre vs Pop

3 m pop: 0.6 +1.25 -1.50 x 66 0.6CLINICAL CASE

Additional video with surgery technique