Differences Between Simulated Keratometry and Total Corneal Power in Eyes With Keratoconus and a Formula to Improve IOL Power Calculation Results.

PURPOSE: To compare simulated keratometry (SimK) and total corneal power (TCP) in keratoconic eyes, to determine whether the differences are systematic and predictable and to evaluate an adjusted TCP-based formula for intraocular lens (IOL) power calculation. METHODS: In a consecutive series of keratoconic eyes, measurements of SimK, TCP, posterior keratometry, and anterior and posterior corneal asphericities (Q-values) were retrospectively collected. The difference between SimK and TCP was linearly correlated to the biometric parameters. In a separate sample of keratoconic eyes that had undergone cataract surgery, IOL power was calculated with the Barrett Universal II, Hoffer QST, Holladay 1, Kane, and SRK/T formulas using the SimK and an adjusted TCP power. The respective prediction errors were calculated. RESULTS: A total of 382 keratoconic eyes (271 patients) were enrolled. An increasing overestimation of SimK by TCP was detected from stage I to III, with a significant correlation between the SimK and TCP difference and SimK in the whole sample (P < .0001, r2 = 0.1322). Approximately 7% of cases presented an underestimation of SimK by TCP. IOL power calculation with the adjusted TCP improved outcomes, achieving a maximum of 80% of eyes with a prediction error within ±0.50 diopters with the Hoffer QST, Holladay 1, and Kane formulas. CONCLUSIONS: Overall, SimK overestimated TCP. Such a difference could not be predicted by any variable. The proposed TCP-adjustment formula (TCPadj = TCP + 0.56 diopters) in keratoconic eyes for IOL power calculation might be valuable for improving refractive outcomes. [J Refract Surg. 2024;40(4):e253-e259.].

Ray-Tracing Transepithelial Excimer Laser Central Corneal Remodeling Plus Pachymetry-Guided Accelerated Corneal Crosslinking for Keratoconus.

PURPOSE: The aim of this study was to report the 12 to 96 months results of a tissue-preservation algorithm based on ray-tracing-guided transepithelial excimer laser central corneal ablation (RT t-PRK) combined with individualized pachymetry-guided accelerated crosslinking (M nomogram ACXL) in young adult patients with stable keratoconus (KC). METHODS: This was a prospective interventional study including 38 eyes of 38 young adult patients (stage II KC) with a mean age of 35 years (range 26-46 years) who underwent simultaneous RT with t-PRK plus pachymetry-based ACXL in the worst eye. The treatments were performed using the iViS Suite iRES Excimer Laser (Ligi, Taranto, Italy). Ray-tracing-guided treatments were planned using the customized interactive programmed transepithelial ablation (CIPTA) 2 web software and diagnostic data were assessed by the Precisio 2 tomographer (Ligi, Taranto, Italy) and Sirius tomographer (C.S.O., Florence, Italy). The main outcome measures included uncorrected distance visual acuity, best spectacle-corrected visual acuity, Kmax, high-order aberrations, minimum corneal thickness, and posterior elevation, with a mean follow-up of 52 months (range 12-96 m). RESULTS: The mean UDVA improved + 3.5 ±1.28 Snellen lines (SL); 38% gained ≥ 4 ±1.34 SLs, 35% ≥ 3 ±1.21 SLs, 22% ≥ 2 ±1.12 SLs, and 5% ≥ 1 ±0.75 SLs. The mean best spectacle-corrected visual acuity increased by + 4.3 ±1.3 SL. Sixty-eight percent gained ≥ 4 ±0.88 SLs and 30% ≥ 3 ±0.78 SL. No SLs were lost. CONCLUSIONS: RT t-PRK plus ACXL significantly improved the quality of vision in patients with KC, preventing overcorrection and minimizing tissue consumption.

Progressive high-fluence epithelium-on accelerated corneal crosslinking: a novel corneal photodynamic therapy for early progressive keratoconus.

Purpose: To assess the preliminary clinical results of a new, progressively higher fluence-pulsed light Epi-On accelerated crosslinking nomogram (PFPL M Epi-On ACXL) in the treatment of progressive keratoconus (KC). Setting: Siena Crosslinking Center, Siena, Italy. Methods: A prospective pilot open, non-randomized interventional study, including 32 eyes of 32 young-adult patients over 26 years old with Stages I-III progressive KC undergoing PFPL M Epi-On ACXL, was conducted. Riboflavin loading was performed by using Paracel I 0.25% for 4 min and Paracel II 0.22% for 6 min. The Avedro KXL System (Glaukos-Avedro, Burlington, USA) was used for pulsed-light accelerated crosslinking (ACXL) at air room 21% oxygenation and 13 min of UV-A irradiation. The treatment fluence was set at 7.2 J/cm2, 8.6 J/cm2, and 10.0 J/cm2 in corneas with baseline pachymetry <420 µm (group 1: 8 eyes), ≥ 420 µm <460 µm (group 2, 11 eyes), and ≥ 460 µm (group 3, 13 eyes), respectively. Uncorrected distance visual acuity (UDVA), best-spectacle corrected visual acuity (BSCVA), Scheimpflug corneal tomography, and anterior segment OCT (AS-OCT) data were collected at baseline and postoperatively at 1, 3, and 6 months. Results: UDVA and BSCVA improved in all groups (P ≤ 0.05). Maximum keratometry values (K max) showed a significant decrease in the 10.0 J/cm2 group (Δ -1.68 D). The coma (HOAs) value improved significantly by the sixth month in all groups. OCT average demarcation lines were 211 ± 19 µm in group 1, 245 ± 23 µm in group 2, and 267 ± 21 µm in group 3. Conclusions: The preliminary results show that pachymetry-based PFPL M Epi-On ACXL nomogram stabilizes ectasia progression. Higher fluence Epi-On ACXL increases CXL penetration, with better functional outcomes in the absence of complications.

Transepithelial Enhanced Fluence Pulsed Light M Accelerated Crosslinking for Early Progressive Keratoconus with Chemically Enhanced Riboflavin Solutions and Air Room Oxygen.

PURPOSE: To assess the 3-year clinical results of the 18 mW 7 J/cm2 transepithelial enhanced fluence pulsed light M accelerated crosslinking in the treatment of progressive keratoconus (KC) with chemically enhanced hyper-concentrated riboflavin solutions without iontophoresis and with air-room oxygenation. SETTING: Siena Crosslinking Center, Siena, Italy. METHODS: Prospective pilot, open non-randomized interventional study including 40 eyes of 30 young adult patients over 21 years old (10 simultaneous bilateral) with early (Stage I and II) progressive KC undergoing TE-EFPL 18 mW/7 J/cm2 ACXL (EFPL M TECXL). The 12 min and 58 s pulsed light (1 s on/1 s off) UV-A exposure treatments were performed with a biphasic corneal soaking using Paracel I 0.25% for 4 min and Paracel II 0.22% for 6 min riboflavin solutions and New KXL I UV-A emitter (Glaukos-Avedro, Waltham, USA) at an air room of 21% oxygenation. All patients completed the 3-year follow-up. RESULTS: CDVA showed a statistically significant improvement in the third postoperative month (Δ + 0.17 d. e.) with a final gain of +0.22 d. eq. AK showed a statistically significant decrease in the sixth postoperative month (Δ - 1.15 diopters). K itmax showed a statistically significant decrease at 1-year follow-up (Δ - 1.3 diopters). The coma value improved significantly by the sixth month (Δ - 0.54 µm). MCT remained stable during the entire follow-up. No adverse events were recorded. Corneal OCT revealed a mean demarcation line depth at 282.6 ± 23.6 µm. CONCLUSIONS: Transepithelial enhanced fluence pulsed light M accelerated crosslinking with chemically enhanced riboflavin solution halted KC progression in young adult patients without iontophoresis and no intraoperative oxygen supplementation addressing the importance of increased fluence.

Chemically-Boosted Corneal Cross-Linking for the Treatment of Keratoconus through a Riboflavin 0.25% Optimized Solution with High Superoxide Anion Release.

The purpose of this study was to evaluate the effectiveness and safety of a novel buffered riboflavin solution approved for corneal cross-linking (CXL) in progressive keratoconus and secondary corneal ectasia. Following the in vivo preclinical study performed on New Zealand rabbits comparing the novel 0.25% riboflavin solution (Safecross®) containing 1% hydroxypropyl methylcellulose (HPMC) with a 0.1% riboflavin solution containing 0.10% EDTA, accelerated epithelium-off CXL was performed on 10 patients (10 eyes treated, with the contralateral eye used as control) through UV-A at a power setting of 9 mW/cm2 with a total dose of 5.4 J/cm2. Re-epithelialization was evaluated in the postoperative 7 days by fluorescein dye test at biomicroscopy; endothelial cell count and morphology (ECD) were analyzed by specular microscopy at the 1st and 6th month of follow-up and demarcation line depth (DLD) measured by anterior segment optical coherence tomography (AS-OCT) one month after the treatment. We observed complete re-epithelization in all eyes between 72 and 96 h after surgery (88 h on average). ECD and morphology remained unchanged in all eyes. DLD was detected at a mean depth of 362 ± 50 µm, 20% over solutions with equivalent dosage. SafeCross® riboflavin solution chemically-boosted corneal cross-linking seems to optimize CXL oxidative reaction by higher superoxide anion release, improving DLD by a factor of 20%, without adverse events for corneal endothelium.

Selective transepithelial ablation with simultaneous accelerated corneal crosslinking for corneal regularization of keratoconus: STARE-X protocol.

PURPOSE: To evaluate the changes in refractive outcomes and corneal aberrations in central and paracentral keratoconus after selective transepithelial topography-guided photorefractive keratectomy combined with accelerated corneal crosslinking (STARE-X). SETTINGS: Centro Polispecialistico Mediterraneo, Siena Crosslinking Center, and University of Messina, Italy. DESIGN: Prospective, interventional, multicentric study. METHODS: Patients were subdivided into 2 groups: Group 1 with cone located within the central 3 mm zone (50 eyes) and Group 2 (50 eyes) with cone located outside the central 3 mm zone. Follow-up was 2 years at least for all eyes. Outcome parameters included uncorrected distance visual acuity (UDVA) and corrected distance visual acuity (CDVA). Corneal tomography and corneal wavefront aberrations were assessed and compared before and 2 years after the treatment. RESULTS: 100 eyes of 100 patients underwent STARE-X protocol. At 2 years, UDVA and CDVA improved, and sphere, cylinder, and Kmax reduced after treatment in both groups (P < .001, respectively). Moreover, a statistically significant reduction was observed of total higher-order aberrations root main square (RMS), coma RMS, and spherical aberration RMS in both groups (P < .001, respectively). However, CDVA improved more in Group 1 than in Group 2 (P < .02). CONCLUSIONS: The STARE-X protocol demonstrated effective results in halting keratoconus progression and improving corneal regularity with a safe and effective profile. STARE-X improved both visual acuity and corneal aberration at 2 years. Longer follow-up studies are warranted to observe further long-term CXL flattening effect on the cone.

Autologous platelet-rich plasma in the treatment of refractory corneal ulcers: A case report.

PURPOSE: To evaluate the efficacy of a low-cost preparation of platelet-rich plasma (PRP) eye drops in the treatment of persistent non-infectious corneal ulcer. OBSERVATIONS: A 67-year-old female presented to our clinic with a wide corneal ulcer and severe paracentral corneal thinning refractory to medical therapy with antibiotics, lubricant and contact lens bandage. The patient received a novel preparation of PRP solution. After 15 days of therapy, we observed complete resolution of the corneal ulcer with regrowth of the epithelium and a reduction in corneal opacity. CONCLUSION AND IMPORTANCE: Although the low-cost PRP preparation gives a lower platelet concentration than standard procedures, our work shows this preparation to be effective in the treatment of refractory non-infectious corneal ulcer.

Enhanced-Fluence Pulsed-Light Iontophoresis Corneal Cross-linking: 1-Year Morphological and Clinical Results.

PURPOSE: To assess the safety and efficacy of a novel pulsed-light enhanced-fluence iontophoresis corneal cross-linking (EF I-CXL) procedure in patients with progressive keratoconus. METHODS: This prospective interventional pilot study included 12 eyes of 10 patients. Iontophoresis with Ricrolin+ solution (Sooft, Montegiorgio, Italy) was used for stromal imbibition. The treatment energy dose (fluence) was optimized at 30% (from 5.4 J to 7 J/cm2) and ultraviolet-A (UV-A) power set at 18 mW/cm2 × 6.28 minutes of exposure time, pulsing the light 1 second on/1 second off with a total irradiation time of 12.56 minutes. Uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), Scheimpflug corneal tomography data, and corneal optical coherence tomography (OCT) at baseline and 1, 3, 6, and 12 months postoperatively were evaluated. RESULTS: Twelve-month statistically significant average data (P < .05) showed UDVA decreased from 0.50 ± 0.10 to 0.36 ± 0.08 logMAR, maximum keratometry decreased from 52.86 ± 1.50 to 51.49 ± 0.90 diopters (D), surface asymmetry index decreased from 2.34 ± 0.36 to 2.13 ± 1.12 D, symmetry index decreased from 4.22 ± 1.01 to 3.56 ± 0.90 D, and coma decreased from 0.25 ± 0.05 to 0.14 ± 0.06 µm. Corneal OCT showed greater than 80% demarcation line detection at 295.8 ± 20.2 µm depth on average in the first postoperative month. CONCLUSIONS: The preliminary results of the EF I-CXL protocol demonstrate its capability to increase I-CXL efficacy closer to standard CXL. [J Refract Surg. 2018;34(7):438-444.].

Evaluation of postoperative toric intraocular lens alignment with anterior segment optical coherence tomography.

We describe the use of a simple tool to evaluate the postoperative alignment of toric intraocular lenses (IOLs). The entire anterior segment is scanned using anterior segment optical coherence tomography and analyzed with an internal dedicated tool. A topographic map is displayed along with an anterior segment image, including a linear axis marker centered on the corneal apex. The marker can be rotated until it is aligned with the line connecting the IOL marking dots, precisely reproducing the IOL astigmatic axis, which is measured in angle degrees. The value of the IOL astigmatic axis is compared with the value of the astigmatic axis shown in real time on the same screen in the topographic map. Evaluating the alignment of a toric IOL axis simultaneously with the topographic astigmatic axis eliminates the potential errors that result from head tilting and strictly correlates with the astigmatic correction achieved.