A novel Q‐value‐based nomogram for single intracorneal ring segment implantation versus standard manufacturer's nomogram combined with accelerated cross‐linking for treatment of keratoconus: a randomized controlled trial

Abstract

Purpose To compare the efficacy of implanting a single Keraring segment according to a novel Q‐value‐based nomogram (QN) to that of segment implantation according to the manufacturer's standard nomogram (SN), for keratoconus treatment. Methods This was a prospective, randomized controlled trial of 104 patients (104 eyes) with Amsler‐Krumeich grade 1 or 2 keratoconus, and type 1 or 2 cone asymmetry determined according to manufacturer's classification. They were randomly distributed into two groups: group A patients (n = 52) underwent Keraring implantation according to the SN, and group B patients (n = 52) underwent implantation of a single (210° arc‐length) Keraring segment according to the QN. Both treatments were combined with accelerated transepithelial cross‐linking, and follow‐up was 6 months. Main outcome measures were preoperative and postoperative visual acuity, subjective refraction and corneal topography. Results At postoperative month 6, group B exhibited statistically significantly higher values of mean uncorrected distance visual acuity (UDVA), sphere, K2, K‐average, K‐max and Q‐anterior (p = 0.02, 0.01, 0.002, 0.001, 0.0001 and 0.03, respectively) compared to that of group A. However, group A exhibited better refractive cylindrical improvements (p = 0.04). In group A, we documented spontaneous extrusion of one Keraring segment. Conclusion Single 210° arc‐length segment implantation using our objective QN was more efficacious for keratoconus treatment than using the subjective SN. The nomograms were comparable when the Q‐anterior value was >−1.00; however, the QN was superior to the SN when the Q‐anterior value was ≤−1.00. The QN yielded greater postoperative UDVA and smoother corneal remodelling than did the SN for treatment of grade 1 and 2 keratoconic eyes.

Analysis of the outcomes of three different cross‐linking protocols for treatment of paediatric keratoconus: A multicentre randomized controlled trial

“…Although there are several treatment strategies for adult keratoconus including CXL, ICRS, photorefractive keratectomy, and combined procedures known as CXL‐Plus and keratoplasty, yet paediatric keratoconus management is mainly targeted with CXL treatment (Abou Samra et al, 2018; Iqbal et al, 2018, 2021; Iqbal, Elmassry, Badawi, Gharieb, & Said, 2019; Iqbal, Elmassry, Tawfik, Elgharieb, et al, 2019; Mazzotta et al, 2018; Mukhtar & Ambati, 2018; Saleem et al, 2018). Hence the importance of this study that focussed on choosing the most appropriate type of CXL for treatment of paediatric keratoconus which is the SCXL.…”

Outcomes of the Q value-based nomogram in managing pediatric versus adult keratoconus: a prospective interventional study

“…The adult group (aged ≥ 18 years) included 33 eyes of 33 patients with KCN, and the pediatric group (aged 14 – 17 years) included 14 eyes of 14 patients with KCN. All patients underwent femtosecond laser-assisted implantation of a single 210° Keraring segment (Keraring ICRS; Mediphacos Ltd., Belo Horizonte, Brazil) according to the novel Q value-based nomogram ( Table 1 ) [ 12 ] .…”

“…All participants were followed up for 6 months. All pediatric eyes underwent CXL after the end of the study, as described in detail elsewhere [ 6 , 12 ] ; however, the accelerated epithelium-off CXL outcomes were not included in this study. All adult and pediatric participants were instructed to continue follow-up at the Cornea Outpatient Clinic at the end of the study.…”

“…Ferrara and Torquetti [ 11 ] revealed that targeting a normal Q value could improve intracorneal ring segment (ICRS) nomograms. Iqbal et al [ 12 ] provided a novel Q value-based nomogram (Q-N) for early grades of KCN to improve the postoperative outcomes of Keraring implantation and to avoid the unpredictable outcomes of the manufacturer’s standard nomogram (S-N). They demonstrated the superiority of the Q-N to the S-N for the treatment of KCN in adult patients with a mean age of 28 years [ 12 ] .…”

Comparison of corneal measurements in normal and keratoconus eyes using Anterior Segment Optical Coherence Tomography (AS-OCT) and Pentacam HR topographer

“…The main treatment options includes corneal cross-linking, intracorneal rings implantation, photorefractive keratectomy, combined procedures (cross-linking plus) and keratoplasty [ 2 – 7 ].…”