Journal List > J Korean Ophthalmol Soc > v.50(10) > 1008388

Kim, Lee, and Lee: Intracorneal Ring Segment Implantation for the Management of Keratoconus: Short-Term Safety and Efficacy

Abstract

Purpose

To assess the safety and efficacy of intracorneal ring segment (Intacs ring) implantation in managing keratoconus.

Methods

This retrospective case series comprised of 11 keratoconic eyes (11 patients) had Intacs ring (Addition Technology, Inc, California, USA) implantation. The main outcome measures were best corrected visual acuity, refraction, keratometry, topography, and pachymetry. Patients were examined before Intacs ring implantation as well as one week, one, three, and six months postoperatively.

Results

The mean best corrected visual acuity improved from 0.60±0.33 logMAR preoperatively to 0.39±0.23 logMAR six months postoperatively (p >0.05) and the mean corneal thickness, from 432.82±41.17 μm preoperatively to 448.00±62.27 μm at six months (p >0.05). The mean cylinder improved from -5.36±2.70D preoperatively to -2.50±1.66D six months postoperatively (p <0.05) and the mean keratometry, from 47.99±2.38D to 42.83±1.72D at six months (p <0.05). In addition, the mean spherical equivalent improved from -6.64±3.49D preoperatively to -3.66±3.37D six months postoperatively (p <0.05). One eye had a risk of ring exposure, but the others had no significant complications.

Conclusions

Intacs ring implantation appears to be effective in improving cylinder, spherical equivalent, and keratometry in patients with keratoconus.

References

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Table 1.
Nomogram for Intacs ring size selection (Addition Technology, Inc, California, USA)
Symmetric
 Spherical equivalent Intacs
 +7.00 to +1.00 0.21 mm
 +0.75 to -1.75 0.25 mm
 -2.00 to -2.75 0.30 mm
 -3.00 to -3.75 0.35 mm
 -4.00 to -4.75 0.40 mm
 -5.00 to -5.75 0.45 mm
 -6.00 to -7.75 0.40 mm SK
 -8.00 and higher 0.45 mm SK
Asymmetric
 Spherical
Inferior
Superior
 equivalent Intacs Intacs
 +1.00 to -2.00 0.30 mm 0.21 mm
 -2.00 to -3.00 0.35 mm 0.21 mm
 -3.00 to -4.00 0.40 mm 0.21 mm
 -4.00 and higher 0.45 mm 0.21 mm
Table 2.
Preoperative and postoperative patient data in patients with keratoconus who underwent Intacs ring implantation
Parameter Mean± SD
Preoperative 1 week 1 month 3 months 6 months
BCVA* (logMAR) 0.60±0.33 0.53±0.29 0.50±0.20 0.45±0.32 0.39±0.23
Cylinder (D) -5.36±2.70 -3.14±2.29 -4.09±3.83 -3.50±1.58 -2.50±1.66§
Spherical equivalent (D) -6.64±3.49 -2.43±3.78 -4.91±5.21 -5.38±3.68 -3.66±3.37§
Mean keratometry (D) 47.99±2.38 41.36±2.90 42.98±2.81 42.99±2.89§ 42.83±1.72
Pachymetry (µm) 432.82±41.17 448.18±58.07 435.64±53.51 431.27±47.30 448.00±62.27

* BCVA=best corrected visual acuity;

Pachymetry=thinnest point;

p<0.01;

§ p=0.01.

Table 3.
Characteristics and outcomes of patients who underwent Intacs ring implantation
Case No. PreOP
PostOP 6 months
Age Sex BCVA*(logMAR) SE(D) Cylinder (D) Mean K(D) Pachymetry§(µm) BCVA*(logMAR) ) SE(D) Cylinder (D) Mean K(D) Pachymetry§(μm)
1 31 M 1.00 -7.50 -5.00 49.40 408 0.15 -7.00 -4.00 43.80 554
2 32 M 1.00 -6.00 -4.00 45.00 442 0.22 -0.75 -1.50 40.00 421
3 32 M 0.40 -8.50 -4.00 48.70 368 0.52 -9.50 -1.00 44.60 378
4 31 F 0.52 -8.00 0.00 49.50 457 0.70 -6.75 -4.50 41.50 420
5 29 M 0.40 -4.50 -9.00 45.00 449 0.10 -0.50 -3.00 42.50 468
6 31 M 0.40 0.00 -6.00 47.80 506 0.70 -0.88 -1.75 45.60 517
7 29 M 0.10 -4.00 -5.00 43.60 478 0.05 0.50 -2.00 40.70 514
8 31 M 0.40 -3.25 -3.50 49.30 448 0.52 -1.13 -1.25 42.90 468
9 31 F 1.00 -8.50 -5.00 50.40 399 0.52 -4.50 -3.00 44.30 432
10 20 M 0.40 -11.50 -9.00 48.60 385 0.40 -3.25 -5.50 43.30 354
11 32 F 1.00 -11.25 -8.50 50.60 421 0.40 -6.50 0.00 41.90 402

* BCVA=best corrected visual acuity;

SE=spherical equivalent;

K=keratometry;

§ pachymetry=thinnest point.

Table 4.
Mean best corrected visual acuity (logMAR), spherical equivalent (diopter) and cylinder (diopter) outcomes by preoperative mean keratometry
Preoperative Keratometry (D) Mean BCVA* (logMAR)± SD
Mean SE± SD
Mean Cylinder± SD
PreOP 6-Month PostOP PreOP 6-Month PostOP PreOP 6-Month PostOP
<49 (6 eyes) 0.45±0.29 0.33±0.25 -5.75±3.96 -2.40±3.69 -6.17±2.32 -2.46±1.63
≥49 (5 eyes) 0.78±0.30 0.46±0.20 -7.70±2.88 -5.18±2.47§ -4.40±3.07 -2.55±1.89

* BCVA=best corrected visual acuity;

SE=spherical equivalent;

p<0.01;

§ p=0.04.

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