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Hindawi Publishing CorporationJournal of OphthalmologyVolume 2015, Article ID 916385, 8 pageshttp://dx.doi.org/10.1155/2015/916385 Clinical Study
Intrastromal Corneal Ring Segment Implantation
(Keraring 355∘) in Patients with Central Keratoconus:
6-Month Follow-Up
Khosrow Jadidi,1 Seyed Aliasghar Mosavi,1 Farhad Nejat,1 Mostafa Naderi,1
Leila Janani,2 and Sara Serahati3
1 Department of Ophthalmology, Bina Eye Hospital Research Center, Tehran 1914853184, Iran2Department of Epidemiology and Biostatistics, School of Public Health, Tehran University of Medical Sciences (TUMS), Tehran, Iran3Department of Biostatistics, University of Social Welfare and Rehabilitation Sciences, Tehran, Iran Correspondence should be addressed to Khosrow Jadidi; [email protected] Received 16 September 2014; Revised 27 November 2014; Accepted 28 November 2014 Academic Editor: Suphi Taneri Copyright 2015 Khosrow Jadidi et al. This is an open access article distributed under the Creative Commons Attribution License,which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
We evaluate the efficacy and safety of Keraring 355∘ intrastromal corneal ring segment (ICRS) implantation aided by PocketMakermicrokeratome for the correction of keratoconus. Patients underwent ICRS insertion using mechanical dissection withPocketMaker microkeratome and completed 6 months of follow-up. Uncorrected visual acuity (UCVA), best spectacle-correctedvisual acuity (BSCVA), refraction, topographic findings, safety, efficacy index, and adverse events were reported for six monthspostoperatively. We evaluated 15 eyes of 15 patients (12 men) with a mean age of 28.87 ± 6.94 years (range 21–49 years). At finalpostoperative examination, there was a statistically significant reduction in the spherical equivalent refractive error compared topreoperative measurements (−5.46 ± 1.52 to −2.01 ± 1.63 D, 𝑃 < 0.001). Mean preoperative UCVA (logMAR) before implantationwas 0.79 ± 0.48, and postoperative UCVA was 0.28 ± 0.15, 𝑃 = 0.001. Mean preoperative BSCVA (logMAR) before implantation was0.36 ± 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 intraoperativeor postoperative complications were demonstrated. This preliminary study shows that ICRS (Keraring 355∘) implantation is anefficient, cost-effective, and minimally invasive procedure for improving visual acuity in nipple type keratoconic corneas.
lenses. In more advanced stages with severe corneal irregularastigmatism and stromal opacities, surgical treatment with Keratoconus is a bilateral, progressive, noninflammatory dis- deep lamellar keratoplasty and penetrating keratoplasty (PK) ease of the cornea which often leads to high myopia and should be considered [9–13].
astigmatism with an estimated prevalence of approximately Intrastromal corneal ring segments (ICRSs) represent a 1 in 2000 [1]. In the general population, the incidence of substantial evolution in the management of keratoconus.
keratoconus is estimated to be between 50 and 230 per100,000 [2–4]. It seems to be a multifactorial disease with Moreover, long-term data on ICRS procedures demonstrated an unknown exact etiology which impairs the quantity and promising results in topographic regularity and uncorrected quality of vision secondary to thinning in and protrusion visual acuity (UCVA), indicating the "possibility of putting of the cornea. This results in an irregular astigmatism with back or even replacing keratoplasty in keratoconus patients" or without myopia [5–7]. Despite the fact that only one eye may be affected initially, keratoconus ultimately affects both Different brands of ICRSs are currently on the market, eyes [8]. The conservative management of keratoconus in including Intacs (Addition Technology, Inc.), Ferrara (Fer- early stages consists of spectacle correction or rigid contact rara Ophthalmics Ltd.), and Keraring (Mediphacos Ltd.).
Journal of Ophthalmology Kerarings are made of medical grade polymethyl methacry- Table 1: Keraring 355∘ ICR nomogram.
late (PMMA) with a UV blocker. They are characterizedby a triangular cross section with variable thickness and an Keraring 355∘ ICR dimension Spherical equivalent arc length that induces a flattening effect on the cornea.
Keraring 355∘ intrastromal corneal ring (ICR; Mediphacos, Minas Gerais, Brazil) is a new unique intracorneal ring design especially developed for a nipple type keratoconus. It is ICR: intrastromal corneal ring.
available in a diameter of 5.7 mm and a thickness range of200 and 300 𝜇m. To our knowledge, there are no reports onthe effect of insertion or implantation of Keraring 355∘ on thepostoperative outcome. To investigate the short-term visual (efficacy index = postoperative uncorrected visual acuity ÷ and refractive outcomes after implantation of Keraring 355∘, preoperative best-corrected visual acuity) [18, 19].
we conducted the current study in which all eyes had a 6- Furthermore, we assessed patient satisfaction with three month follow-up.
different questions. We asked every patient about their overallsatisfaction with ICRS implantation after three years based 2. Materials and Method
on a six-point Likert scale ((0) no satisfaction; (1) very littlesatisfaction; (2) little satisfaction; (3) moderate satisfaction; This prospective, consecutive, interventional study included (4) high satisfaction; (5) very high satisfaction). We also 15 eyes from 15 patients (12 men, 3 women) with a mean age asked patients the questions "Would you recommend this of 28.87 ± 6.94 years (range 21 to 49 years) with keratoconus.
procedure to other patients?" And "Would you have ICRS It was approved by The Institutional Review Board of the Eye implantation for the other eye?" Research Center, Bina Eye Hospital, and followed the tenetsof the Declaration of Helsinki. After fully explaining the 2.1. Surgical Procedure. All surgical procedures were per- purpose and procedures of the study, all patients were asked formed by the same experienced surgeon (Khosrow Jadidi) to sign an informed consent form before treatment. Inclusion in an operating room under topical anesthesia with propara- criteria were nipple type keratoconic eyes with clear central caine hydrochloride 0.5% (Alcaine, Alcon) drops. In order cornea, age between 21 and 49 years, minimum corneal to mark the central point of intrastromal corneal ring thickness of 360 microns, mean keratometry between 45 and implantation, the operation microscope (OMS-800 Standard 52 D, contact lens intolerance, an uncorrected visual acuity TOPCON Corporation, Japan) was used. In addition to the (UCVA) not better than 20/50, and no visual dysfunctions above, the pupil center was marked for proper centralization.
other than keratoconus. Contact lens wear was discontinued The surgical procedure included creation of a pocket within three weeks prior to the exams. Exclusion criteria were the corneal stroma of 8.5 mm in diameter at 300-micron positive pregnancy test, breast-feeding, history of vernal depth using a PocketMaker microkeratome (Dioptex GmbH) and atopic keratoconjunctivitis, history of keratorefractive as described elsewhere [28, 38, 39] with a minor modification: surgery on the operative eye, patients with dry eye, history when correct position of the blade was determined, the of corneal stromal disorders, nystagmus, immunosuppressive microvibrating diamond blade was set at 300 𝜇m of the drugs users, hyperopia, advanced keratoconus with inferior measured corneal thickness and a single 2 mm radial incision corneal thinning less than 360 𝜇m, and patients with severe was made at the steepest meridian. Then, the applicator was ocular and systemic pathologies (e.g., history of herpes ker- fixated to the eye by the suction ring. The suction ring was atitis, diagnosed autoimmune disease, systemic connective removed from the eye after creating a closed intrastromal tissue disease, glaucoma, cataract, diabetic retinopathy, and pocket of 8.5 mm diameter and 300 𝜇m depth through age-related macular degeneration). A complete ophthalmic the small incision tunnel. The Keraring 355∘ segment was examination was performed preoperatively and postoper- inserted at the steepest meridian into the circular channel via atively, including uncorrected visual acuity (UCVA), best the notch, using implantation forceps. The appropriate Kerar- spectacle-corrected visual acuity (BSCVA), manifest refrac- ing 355∘ segment thickness was selected and then implanted tion, spherical equivalent (SE), keratometry (𝐾) readings, in the eye according to the new nomogram designed based on and ultrasound pachymetry. Corneal topography was mea- the author's experiences (Table 1 and Figure 1). The centration sured using the Orbscan II Slit Scanning Corneal Topog- of the implant was adjusted using keratoscope. Subsequently, raphy/Pachymetry System (Orbscan II, Bausch & Lomb).
a silicone-hydrogel bandage contact lens (Bausch & Lomb) Visual acuity was measured using Snellen notation and then was placed on the cornea. Postoperatively, patients were converted to logMAR for statistical analysis. Diagnosis of prescribed betamethasone drops (Sina Darou) four times a keratoconus was established by the combination of computer- day, chloramphenicol drops (Sina Darou) four times a day, ized video keratography of the anterior and posterior corneal and nonpreserved artificial tears (Artelac, Bausch & Lomb, surfaces (Orbscan IIz), 𝐾 readings, and corneal pachymetry France) six times per day. Chloramphenicol drops were [16, 17]. The safety of implantation of Keraring 355∘ in patients discontinued one week postoperatively, but betamethasone with keratoconus was assessed using a refractive surgery drops were tapered after four to six weeks. The bandage safety index (safety index = postoperative best-corrected contact lens was removed one day postoperatively. Patients visual acuity ÷ preoperative best-corrected visual acuity).
were then scheduled for postoperative clinical examinations Efficacy was assessed using a refractive surgery efficacy index at one month and three and six months.
Journal of Ophthalmology Figure 1: Slit-lamp examination of an eye with keratoconus one month and 3 months after Keraring 355∘ ICR implantation.
Table 2: Characteristic of participants.
(Figure 2). The safety index was 1.26 at six months. There wasa significant improvement in spherical equivalent refractive Number of patients error from −5.46±1.52 diopters (D) preoperatively to −2.01± 1.63 (𝑃 < 0.001) at 6 months postoperatively (Table 3). The mean 𝐾 readings improved in the same period, from 48.11 ± 1.95 D to 43.31 ± 2.31 (𝑃 < 0.001) (Figure 3). Our results present a significant flattening effect postoperatively, since the mean topographic 𝐾 values showed decreases in 𝐾mean, 𝐾max, and 𝐾min at six months postoperatively (𝑃 < 0.001).
The means (standard deviation) of all data are shown inTables 3 and 4. Postoperatively, UCVA and BSCVA showed a significant improvement and sphere, cylinder, SE, and keratometry readings were significantly reduced. Moreover,postoperatively, all eyes showed excellent corneal toleranceto intrastromal corneal segment. In addition, all patients were 2.2. Statistical Analysis. Continuous variables with normal satisfied with Keraring 355∘ implantation. Likewise, on a scale distribution are presented as mean ± SD. The paired 𝑡-test of 0 to 5 for current overall satisfaction, 86.7% of patients was used to compare preoperative and postoperative values noted that they were moderately to very happy with the of UCVA, BSCVA, SE, 𝐾max, 𝐾min, and 𝐾mean. The difference results (scores 3–5) (Table 5).
as a function of time was analyzed using paired two-tailed 𝑡-tests (at time intervals before operation to three months, before operation to six months, and three to six months of thefollow-up period). Statistical analysis was performed using The purpose of the present study was to determine the the SPSS 18.0 software (SPSS Inc., Chicago, IL, USA). 𝑃 values effects of Keraring 355∘ on uncorrected visual acuity (UCVA), less than 0.05 were considered statistically significant.
best spectacle-corrected visual acuity (BSCVA), refraction,topography, and the safety and efficacy indices in keratoconic 3. Results
Several possible alternatives to manage keratoconus have In this study, 15 eyes of 15 patients were evaluated. The mean been reported in the literature, including scleral-fitted gas- age of the patients was 28.87 ± 6.94 years (range 21 to 49 permeable contact lenses, inferior eccentric penetrating years), and the male/female ratios were 4 : 1 (Table 2). The last grafts, deep lamellar keratoplasty, penetrating keratoplasty, postoperative follow-up time was six months. No intraop- and a recently developed therapeutic tool: intrastromal erative or postoperative complications were detected in this corneal ring segments (ICRSs).
series of patients. Postoperatively, all eyes showed excellent ICRSs were designed with the goal of delaying or avoid- corneal tolerance to the intrastromal corneal segments. The ing corneal grafts in keratoconus patients. It represents a mean UCVA improved significantly from 0.79 ± 0.48 log- prominent evolution in the management of keratoconus via MAR preoperatively to 0.28 ± 0.15 logMAR (𝑃 = 0.001) flattening the central corneal curvature to achieve a refractive six months after implantation (Figure 2). The efficacy index adjustment due to the removable and tissue saving nature was 3.12 at six months. The mean preoperative BSCVA was of the technique. The high efficiency of Intacs in correcting 0.36 ± 0.21 logMAR. The mean BSCVA improved to 0.18 ± keratoconic eyes has been reported by several authors [9– 0.9 logMAR (𝑃 = 0.009) at six months after implantation 14, 23–30]. ICRS implantation in post-Lasik ectasia appears to Journal of Ophthalmology Table 3: Comparison between preoperative and postoperative visual outcomes.
3 versus pre.
6 versus pre.
Sphere (D) Cylinder (D) SE (D)Mean (SD) Notes: UCVA: uncorrected visual acuity; BSCVA: best spectacle-corrected visual acuity; D: diopters; logMAR, logarithm of the minimum angle of resolution;SD: standard deviation; SE: spherical equivalent. Significances are based on paired 𝑡-test. ∗𝑃 < 0.05; ∗∗𝑃 < 0.01.
Figure 2: Mean change in visual acuity. Mean uncorrected visual acuity (a) and best spectacle-corrected visual acuity (b) after Keraring 355∘implantation during the follow-up period.
Table 4: Comparison between preoperative and 6-month postoper- Table 5: General satisfaction of participants 6 months after opera- ative 𝐾 values.
Satisfaction score (𝑁 = 15) 𝐾max value (D) 𝐾min value (D) Note: SD: standard deviation; D: diopter; significances are based on paired 𝑡-test. ∗∗𝑃 < 0.01. 𝐾min: minimum curvature; 𝐾max: maximum curvature; improvement of UCVA and BSCVA in keratoconus patients mean: mean curvature.
[9, 20, 22, 24, 25, 30–40].
Keraring 355∘ is a new intracorneal ring design made of be safe and effective in decreasing myopia, corneal steepness, polymethyl methacrylate (PMMA) and is especially devel- and decentration of the corneal apex and offers potential oped for a nipple type keratoconus. Femtosecond laser is Journal of Ophthalmology Figure 3: Preoperative (top left) and postoperative topographies at 3 months (top right) after Keraring 355∘ ICR implantation.
the suggested technique for implantation. However, manual a mechanical and femtosecond laser tunnel creation in other and mechanical techniques are not prohibited.
studies [43–45].
Mechanical dissection and femtosecond laser are the Coskunseven et al. reported improvement of CDVA in two main techniques generally used for tunnel creation 15.68% of 50 eyes, a decrease in the mean keratometry from during ICRS implantation [41]. The traditional mechanical 50.6 D to 47.5 D and the mean SE from −5.6 D to −2.4 D technique for tunnel creation can cause complications such after ICRS implantation at 1 year [43]. Similarly, Kubaloglu as epithelial defects at the keratotomy site, extension of et al. compared the outcomes of Keraring ICRS implantation the incision, anterior and posterior perforations, infectious with mechanical and femtosecond laser tunnel creation and keratitis, shallow placement of intrastromal corneal ring demonstrated an improvement of the UDVA and CDVA in86% and 88% of eyes, respectively. In addition, a decrease segments, decentration, asymmetric placement, persistent in the mean maximum 𝐾 value from 53.5 D to 48.9 D and incisional gaping, corneal stromal edema around the incision, an improvement in the mean SE from −5.05 to −1.87 D at 1 and stromal thinning [21, 22, 32].
year in femtosecond laser group were found. The UDVA and A study by Hellstedt et al. demonstrated a 35% rate of CDVA were improved in 88% and 84% of eyes, respectively.
postoperative complications such as corneal melt, segment The mean maximum 𝐾 value decreased from 54.1 D to 43.8 D, movement, and exposure with the mechanical tunnel dis- and the mean SE went from −5.75 to 0.75 D at 1 year in the section method [32]. These complications could be reduced mechanical group [44].
with femtosecond laser due to the more precise localization, In our study, we used the mechanical technique to create dimensions, diameter, depth, and width of the channel.
a pocket within the corneal stroma with the PocketMaker Despite this, Ferrer et al. found no significant difference microkeratome (Dioptex GmbH). According to our experi- between the use of femtosecond laser and mechanical dissec- ences, this technique is substantially less expensive than the tion [42]. Also, a significant improvement in CDVA, UDVA, femtosecond laser technique. Secondly, decentralization is and 𝐾 readings after ICRS implantation was reported with manageable and even reversible. Thirdly, with the mechanical Journal of Ophthalmology technique, reshaping and remodeling of the cornea are more Conflict of Interests
feasible than with the femtosecond laser technique.
In our cases, postoperative results revealed a significant The authors declare that there is no conflict of interests reduction in the magnitude of corneal steepening, an increase regarding the publication of this paper.
in topographical regularity, and an improvement in theUCVA and BSCVA when the Keraring 355∘ was implanted at 300 𝜇m thickness (see Table 3). Furthermore, all operationswere uneventful, and no extrusions of the rings were found.
The authors would like to acknowledge the staff of the Additionally, the integrity of the cornea was well preserved in Eye Clinic in Bina Eye Hospital Research Center for their invaluable help during the entire process of this study.
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