Evaluating the safety and effectiveness of the sub-400 corneal cross-linking protocol: initial clinical and morphological findings.

To assess the safety and the efficacy of the "Sub-400 corneal cross-linking (CXL) protocol" for progressive keratoconus (KC) in ultrathin corneas. The study included thirty four patients with progressive KC, who underwent CXL using the "Sub-400" protocol due to intraoperative thinnest corneal pachymetry ranging from 295 to 398 μm after epithelial removal. After the epithelium was removed, the following ultraviolet A irradiation was applied at a fluence of 3 mW/cm2 and the duration was adjusted based on the specific corneal stromal thickness. In addition to slit-lamp microscopy and visual acuity assessment, our evaluation included measurements of the maximal anterior keratometry value (Kmax), mean anterior and posterior K values (Kmean), thinnest corneal thickness (TCT), central corneal thickness, intraoperative pachymetry, and corneal endothelial cell density (ECD) preoperatively and 1 year postoperatively. Stromal demarcation line depth (DL) was measured in the first postoperative month. At the first year postoperative follow-up visit, 88% (30 eyes) exhibited tomographic stability, with average values of change in Kmax (ΔKmax) 0.61 ± 6.45 D after CXL. None of the eyes showed signs of endothelial decompensation. The mean DL depth was 250.76 ± 44.05 μm. Moderate positive correlations were observed between DL and ultraviolet A irradiation time, DL, and intraoperative stromal thickness (r = 0.473, p = 0.005 and r = 0.517, p = 0.002, respectively). ΔKmax was negatively correlated with preoperative Kmax (r =  - 0.559, P = 0.001) and positively correlated with preoperative TCT (r = 0.373, P = 0.030). The "Sub-400 protocol" for CXL has a broad application possibility for ultrathin corneas with KC and has shown promising results.

Karaca EE ，Asfuroğlu Y ，Ulusoy DM ，Evren Kemer Ö ... -  《-》

Biomechanical changes following corneal crosslinking in keratoconus patients.

To evaluate the biomechanical and tomographic outcomes of keratoconus patients up to four years after corneal crosslinking (CXL). In this longitudinal retrospective-prospective single-center case series, the preoperative tomographic and biomechanical results from 200 keratoconus eyes of 161 patients undergoing CXL were compared to follow-up examinations at three-months, six-months, one-year, two-years, three-years, and four-years after CXL. Primary outcomes included the Corvis Biomechanical Factor (CBiF) and five biomechanical response parameters obtained from the Corvis ST. Tomographically, the Belin-Ambrósio deviation index (BAD-D) and the maximal keratometry (Kmax) measured by the Pentacam were analyzed. Additionally, Corvis E-staging, the thinnest corneal thickness (TCT), and the best-corrected visual acuity (BCVA) were obtained. Primary outcomes were compared using a paired t-test. The CBiF decreased significantly at the six-month (p < 0.001) and one-year (p < 0.001) follow-ups when compared to preoperative values. E-staging behaved accordingly to the CBiF. Within the two- to four-year follow-ups, the biomechanical outcomes showed no significant differences when compared to preoperative. Tomographically, the BAD-D increased significantly during the first year after CXL with a maximum at six-months (p < 0.001), while Kmax decreased significantly (p < 0.001) and continuously up to four years after CXL. The TCT was lower at all postoperative follow-up visits compared to preoperative, and the BCVA improved. In the first year after CXL, there was a temporary progression in both the biomechanical CBiF and E-staging, as well as in the tomographic analysis. CXL contributes to the stabilization of both the tomographic and biomechanical properties of the cornea up to four years postoperatively.

Felter E ，Khoramnia R ，Friedrich M ，Son HS ，Auffarth GU ，Augustin VA ... -  《-》

Corneal Collagen Cross-linking for Keratoconus in Pediatric and Developmentally Delayed Patients.

Corneal cross-linking (CXL) is the standard of care in patients with keratoconus but presents unique challenges in children and developmentally delayed patients. We present our clinical decision-making algorithm, CXL surgical technique, and outcomes in these groups. A retrospective chart review was undertaken at a tertiary referral center of all patients who underwent CXL for keratoconus at University of Pittsburgh Medical Center (UPMC) Children's Hospital of Pittsburgh between October 1, 2017, and April 1, 2021. Demographic information along with preoperative, intraoperative, and postoperative ophthalmic examination findings were collected. The main outcome measures were indications of CXL, postoperative complications, and visual acuity (VA). Forty-eight eyes of 34 patients [21 patients (30 eyes) with developmental delay (DD) and 13 patients (18 eyes) with no DD (NDD)] underwent epithelium-off, standard CXL. General anesthesia was used for CXL in all patients except for 3 with NDD. A temporary central tarsorrhaphy was performed in all patients with DD and 7 patients with NDD. The remaining got a bandage contact lens. There were no immediate postoperative complications. A trend toward improvement in VA was noted postoperatively. The mean logMAR VA (with habitual correction) was 0.67 preoperatively and 0.57 postoperatively ( P = 0.3) in DD and 0.52 and 0.36, respectively ( P = 0.13), in NDD. This retrospective review presents a technique for assessment and treatment of keratoconus in children and those with DD. Our technique ensures timely diagnosis and provides a safe method for CXL in these groups. Temporary central tarsorrhaphy is a well-tolerated option to reduce postoperative pain.

Conner E ，Gagrani M ，Lalgudi VG ，Shah PR ，Hiasat J ，Jhanji V ，Nischal KK ... -  《-》

The impact of interrupted corneal collagen crosslinking (CXL) treatment.

To evaluate progression of keratoconus in patients where CXL treatment was interrupted due to insufficient swelling of the cornea. A retrospective review was conducted of all patients with keratoconus diagnosis who underwent CXL at the Department of Ophthalmology, Örebro University Hospital (USÖ) during the years 2010-2017. In total 377 eyes of 280 patients were screened for inclusion. In 17 eyes (15 patients), the treatment was interrupted due to insufficient swelling of the cornea. Patient journals were reviewed and keratometry examinations were analysed for long-term progression. Eleven eyes (nine patients) were included in the study. Five eyes showed no signs of progression after the interrupted CXL treatment. In one eye progression continued, however, first after a period of a number of years, indicating a delayed course of clinical progression. This study indicates that debridement of the corneal epithelium and riboflavin administration without intense UVA radiation may slow or arrest the progression of keratoconus, likely due to photosensitisation from ambient light.

Tholvsen M ，Makdoumi K 《-》

Efficacy and Safety of the Modified Cretan Protocol in Patients with Post-LASIK Ectasia.

To investigate the clinical efficacy and safety of the modified Cretan protocol in patients with post-laser in situ keratomileusis ectasia (PLE). In this retrospective study, 26 eyes of 16 patients with PLE were treated with the modified Cretan protocol (combined transepithelial phototherapeutic keratectomy and accelerated corneal collagen cross-linking). Visual, refractive, tomographic, and aberrometric outcomes and point spread function (PSF) were recorded preoperatively and at 6, 12, and 24 months after treatment. Both uncorrected and best corrected visual acuity were stable at 24 months postoperatively compared to baseline (from 0.89±0.36 to 0.79±0.33 logarithm of the minimum angle of resolution [LogMAR] and 0.31±0.25 to 0.24±0.19 LogMAR, respectively, p>0.05 for all values). The mean K1, K2, Kmean, thinnest corneal thickness, and spherical aberration at baseline were 45.76±5.75 diopters (D), 48.62±6.17 D, 47.13±5.89 D, 433.16±56.86 μm, and -0.21±0.63 μm respectively. These values were reduced to 42.86±6.34 D, 45.92±6.74 D, 44.21±6.4 D, 391.07±54.76 μm, and -0.51±0.58 μm at 24 months postoperatively (p<0.001, p=0.002, p<0.001, p=0.001, and p=0.02, respectively). The mean spherical equivalent, manifest cylinder, Kmax, central corneal thickness, other corneal aberrations (root mean square, trefoil, coma, quatrefoil, astigmatism), and PSF remained stable (p>0.05 for all variables), while anterior and posterior elevation were significantly improved at 24 months postoperatively (p<0.001 and p=0.02, respectively). No surgical complications occurred during the 24-month follow-up. The modified Cretan protocol is a safe and effective treatment option for PLE patients that provides visual stabilization and significant improvement in topographic parameters during the 24-month follow-up. Further studies are needed to support our results.

Tanrıverdi B ，Saraç Ö ，Temel B ，Dağ Şeker E ，Çağıl N ... -  《-》