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Abstract
Purpose
To report the outcomes after the implantation of intrastromal corneal ring segments (KeraRing®) by manual tunnel creation for the correction of keratoconus.
Methods
The present retrospective case series was comprised of 12 eyes of 11 consecutive keratoconic patients. Intrastromal corneal ring segments (KeraRing®) were implanted for keratoconus correction after manual tunnel creation. Uncorrected visual acuity (UCVA), best corrected visual acuity (BCVA), refractive outcome, and complete ophthalmologic examinations were performed before and after surgery at 1 day, 1 week, 3 months, and 6 months. Corneal topography was measured before surgery, 6 months after surgery and during any necessary followup visits.
Results
Intrastromal corneal ring segments (KeraRing®) implantation significantly increased BCVA from logMAR 0.47 ±0.19 to logMAR 0.28 ± 0.17 (p < 0.05) and decreased the spherical equivalent from −6.03 ± 3.24 D to −2.24 ± 1.96 D. The simulated keratometric value in the Orbscan IIz significantly decreased in K maximum from 50.7 ± 2.93D to 47.65 ± 3.15 D and in K minimum from 47.65 ± 3.15 D to 44.92 ± 2.80 D.
Conclusions
Intrastromal corneal ring segments implantation (KeraRing®) by manual tunnel creation appears to be effective in improving BCVA and reducing corneal astigmatism and keratometric value in keratoconic patients. KeraRing® may delay or prevent the need for a corneal graft, and reduce the contact lens intolerance.
References
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Figure 1.
Corneal ectasia type. Ectatic type 1: 100% of the corneal ecstatic area is located on one side of the steepest corneal meridian (A). Ectatic type 2: Approximately 1/3 of the ectatic area is located on one side of the steepest corneal meridian and 2/3 located on the opposite side (B). Ectatic type 3: The ectatic area is almost evenly distributed on both sides of the steepest corneal meridian (C).
Figure 2.
Surgical procedure of KeraRing® intrastromal corneal ring segment implantation. Purkinje reflex was chosen as the central point and was marked (A). A 5 mm marker was used to locate the exact ring channel (B). Tunnel depth was set at 80% of the thinnest corneal thickness using the diamond scalpel (C, D). Pocket was created by using the Grupenmacher microdissector (E). And then, instromal channel was created by using the Suarez's spreader (F). KeraRing® intrastromal corneal ring segment was implanted after channel creation using the Albertazzi's forceps (G, H). Finally, cornea was put on the therapeutic lens (I).
Figure 3.
Preoperative corneal topography (A). Patient's manifest refraction was (−4.5)×(−5.5)cyl 90˚. Best corrected visual acuity was 0.4 (logMAR). And ectatic area is almost evenly distributed on both sides. planed KeraRing® intrastromal corneal ring segment according to normogram (B). Postoperative corneal topography (C). Implanted KeraRing® intrastromal corneal ring segment inside the stromal tunnel (D). Best corrected visual acuity was 0.2 (logMAR) postoperatively.
Figure 4.
A 19-year-old male had KeraRing® implantation of 2 intrastromal corneal ring segments in December 2008. Marked improvement was reported by the patient during 3 months. However slit-lamp examination revealed inferior migration of the temporal segment and epithelial protrusion (A). Temporal segment is partially extruded from the wound. And the segment was explanted in March 2009 (B, C). An Obvious wound haziness persisted after explantation (D).
Table 1.
Technical specifications of KeraRing® intrastromal corneal ring segment
Table 2.
Preoperative and postoperative (6 months) examination data of patients with keratoconus after KeraRing® intrastromal corneal ring segment implantation
| Parameter |
Preoperative |
Postoperative (6 mon) |
|
|---|---|---|---|
| Mean ± SD | Mean ± SD | ||
| BCVA (logMAR) | 0.47 ± 0.19 | 0.28 ± 0.17 | p < 0.05 |
| Spherical equivalent (D∗) | -6.03 ± 3.24 | -2.24 ± 1.96 | p < 0.01 |
| Cylinder (D∗) | -4.08 ± 1.38 | -1.94 ± 1.82 | p < 0.01 |
| Sim K (maximum) (D∗) | 50.70 ± 2.93 | 47.65 ± 3.15 | p < 0.01 |
| Sim K (minimum) (D∗) | 45.73 ± 3.21 | 44.92 ± 2.80 | p < 0.01 |
| Sim K astigmatism (D∗) | 5.01 ± 1.88 | 2.74 ± 1.07 | p < 0.01 |
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