Intrastromal Corneal Ring Segment Implantation (Keraring 355°) in Patients with Central Keratoconus: 6-Month Follow-Up

Abstract

We evaluate the efficacy and safety of Keraring 355° intrastromal corneal ring segment (ICRS) implantation aided by PocketMaker microkeratome for the correction of keratoconus. Patients underwent ICRS insertion using mechanical dissection with PocketMaker microkeratome and completed 6 months of follow-up. Uncorrected visual acuity (UCVA), best spectacle-corrected visual acuity (BSCVA), refraction, topographic findings, safety, efficacy index, and adverse events were reported for six months postoperatively. We evaluated 15 eyes of 15 patients (12 men) with a mean age of 28.87 ± 6.94 years (range 21–49 years). At final postoperative examination, there was a statistically significant reduction in the spherical equivalent refractive error compared to preoperative measurements (−5.46 ± 1.52 to −2.01 ± 1.63 D, P < 0.001). Mean preoperative UCVA (logMAR) before implantation was 0.79 ± 0.48, and postoperative UCVA was 0.28 ± 0.15, P = 0.001. Mean preoperative BSCVA (logMAR) before implantation was 0.36 ± 0.21; at final follow-up examination BSCVA was 0.18 ± 0.9, P = 0.009. Mean K decreased from 48.33 to 43.31 D, P < 0.001. All patients were satisfied with ICRS implantation; 86.7% were moderately to very happy with the results. No intraoperative or postoperative complications were demonstrated. This preliminary study shows that ICRS (Keraring 355°) implantation is an efficient, cost-effective, and minimally invasive procedure for improving visual acuity in nipple type keratoconic corneas.

Aberrometric Outcomes of Intrastromal Corneal Ring Segment (KeraRing 355) Implantation Using PocketMaker Microkeratome in Patients with Keratoconus

“…Considering primary spherical error, As Pinero et al [19] mentioned, mechanical method to implant intrastromal segment can result in negative increase in spherical error, our study shows increase in a negative direction which accords with previous studies [25][26][27][28]. Secondary spherical error and quadrafoil also showed significant increase despite secondary astigmatism error which remained the same.…”

“…At the next step, suction ring was removed and Keraring 355 was implanted in the pocket. The surgeon chose the suitable thickness for Keraring 355 based on a pre-designed nomogram; a custom-surgeon nomogram [26]. The cornea was covered by a silicone-hydrogel bandage contact lens (Bausch & Lomb).…”

“…Arcuate length variability results in better correction of astigmatism in keratoconus patients [22] To our knowledge, there are limited studies investigating Keraring 355 with high attention in KCN treatment. On the other hand, most studies measuring corneal aberration used topography [26][27][28][29][30][31][32][33]. In the present study, we investigated Keraring intrastromal segment effect on optical aberrations in KCN treatment using wave front analyzer which evaluates 80.000 points compared to topography evaluating 6.144 points [34].…”

Agreement Between Autorefraction and Subjective Refraction in Keraring-Implanted Keratoconic Eyes

“…This finding is much better than that reported for keratoconic eyes treated with photorefractive keratectomy (PRK) 13 in which the authors found that the refractive readings obtained with two automated devices varied more from subjective refraction after treatment with PRK. This could be due to the fact that compared with PRK, keraring insertion technique is minimally invasive and the technique was designed to regularize the corneal surface, improve visual acuity, and reduce refractive errors 38,39 or it may be due to the different pupil analysis diameters used by the autorefractors which were suggested to influence the agreement between refractive techniques. 40 The visual acuity measured with subjective refraction increased from 0.1860.14 logMAR preoperatively to 0.1060.10 logMAR postoperatively.…”

Visual Acuity and Contrast Sensitivity Depending from Keratoconus Apex Position

“…Keratoconus incidence is 1 of 2000 persons. Keratoconus is a multifactorial disease of unknown etiology, which impairs visual quality of the cornea because of thinning and protrusion, resulting in an irregular astigmatism with or without myopia (Jadidi et al, 2015). Change of corneal shape for keratoconus patients can change the optical quality of the eye and retinal image quality.…”