Ozonated Oil in Liposome Eyedrops Reduces the Formation of Biofilm, Selection of Antibiotic-Resistant Bacteria, and Adhesion of Bacteria to Human Corneal Cells.

The recent attention to the risk of potential permanent eye damage triggered by ocular infections has been leading to a deeper investigation of the current antimicrobials. An antimicrobial agent used in ophthalmology should possess the following characteristics: a broad antimicrobial spectrum, prompt action even in the presence of organic matter, and nontoxicity. The objective of this study is to compare the antimicrobial efficacy of widely used ophthalmic antiseptics containing povidone-iodine, chlorhexidine, and liposomes containing ozonated sunflower oil. We determined the minimum inhibitory concentration (MIC) on various microbial strains: Staphylococcus aureus (ATCC 6538), methicillin-resistant Staphylococcus aureus (ATCC 33591), Staphylococcus epidermidis (ATCC 12228), Pseudomonas aeruginosa (ATCC 9027), and Escherichia coli (ATCC 873). Furthermore, we assessed its efficacy in controlling antibiotic resistance, biofilm formation, and bacterial adhesion. All three antiseptic ophthalmic preparations showed significant anti-microbicidal and anti-biofilm activity, with the liposomes containing ozonated sunflower oil with the highest ability to control antibiotic resistance and bacteria adhesion to human corneal cells.

Accuracy of intraocular lens power calculation for cataract surgery after deep anterior lamellar keratoplasty.

BACKGROUND: The purpose of this study was to assess the accuracy of intraocular lens power (IOL) formulas for cataract surgery after deep anterior lamellar keratoplasty (DALK). METHODS: This retrospective study included eyes which had previously undergone DALK and underwent standard phacoemulsification with monofocal IOL implantation between January 2012 and January 2021 at Ospedali Privati Forlì "Villa Igea" (Forlì, Italy). The predicted spherical equivalent (SE) was calculated using the Barrett Universal II, Emmetropia Verifying Optical (EVO), Haigis, Hoffer Q, Hoffer QST, Holladay 1, Holladay II, Kane and SRK/T formulas. Prediction error (PE) was calculated as the actual postoperative SE refraction minus the SE predicted refraction. RESULTS: Eighty-two eyes of 82 patients were included. The mean PE was negative using all formulas. Friedman test revealed a statistically significant difference of the median absolute PE (MedAE) among the different IOL formulas (P = 0.005). On the basis of the MedAE, the formulas were ranked as follows: SRK/T (0.805 D), Kane (0.810 D), EVO (0.845 D), Hoffer QST (0.847 D), Barrett (0.895 D), Holladay 1 (0.915 D), Haigis (1.010 D) and Hoffer Q (1.070 D) formulas. CONCLUSIONS: All formulas had a tendency towards a myopic refractive shift in post-DALK eyes. Although the SRK/T, Kane, EVO and Hoffer QST formulas were more accurate, predictability of refractive outcomes was lower than in virgin eyes.

Opaque bubble layer incidence in Femtosecond laser-assisted LASIK: comparison among different flap design parameters.

The purpose of this study was to evaluate the incidence of opaque bubble layer (OBL) in femtosecond laser-assisted in situ keratomileusis (LASIK) flaps created with the support of Visumax Carl Zeiss femtosecond laser, planned with different flap diameters (7.90, 8.0, and 8.20 mm) and the same laser energy and power settings. Incidence of intraoperative OBL in flaps of consecutive 108 patients (216 eyes) subjected to bilateral femtosecond-assisted LASIK was considered. Flap creation was performed with the same laser design parameters (spot distance and energy offset) and different presetting diameters of 7.90 mm (72 eyes, group 1), 8 mm (72 eyes, group 2), and 8.20 mm (72 eyes, group 3). The incidence of OBL was considered and its extension was reported measuring involvement of different four corneal flap quadrants in which was theoretically divided the entire flap area; based on these data, OBL presence was classified as none (no evidence of OBL), minimal (minimal presence in not more that one quadrants corneal flap), mild (OBL presence in almost two or three quadrants without tendency to invade central cornea), and moderate (OBL presence in almost three quadrants with tendency to invade central cornea). In group 1, the incidence of OBL was of 23.6 % (17 eyes) with a mild/moderate presence; in group 2, incidence was 20.8 % (15 eyes) with mild presence. Group 3 presented a reduced OBL incidence (4.1 %, 3 eye) with a minimal presence. No statistically significant difference was found between group 1 and 2 (p = 0.8414).We found statistically significant differences between group 1 and group 3 (p = 0.0012) and between groups 2 and 3 (p = 0.0044). A significant reduction and extension of OBL incidence were evident when LASIK flap settings diameter was increased, and flap edge was closer to the contact glass border; this is probably consequent to a more effective gas dispersion outside of corneal flap.

Ex Vivo Lenticule Customization for Stromal Lenticule Addition Keratoplasty.

Purpose: The purpose of this study was to explore the optimal shape of customized lenticules for stromal lenticule addition keratoplasty (SLAK) for off-centered ectasia. Methods: Two different methods to create ex vivo models of eccentric-keratoconus were investigated. Twelve human corneas were used to create model 1 by a hyperopic photorefractive keratectomy (PRK), and model 2 by masked phototherapeutic keratectomy (PTK) on the anterior corneal surface, whereas both types received myopic ablation of the posterior surface. Keratoconus models underwent a modified femtosecond laser (FSL) flap-cut to create stromal pockets. Sixteen human corneas underwent FSL dissection to obtain four lenticule types: type I (planar) and type II (negative) lenticules were used without modifications, whereas type III (customized-planar), and type IV (customized-negative) lenticules underwent further masked-PRK to obtain an asymmetric bow-tie shape. Topographic, aberrometric analysis, and anterior segment optical coherence tomography (AS-OCT) were performed in all recipient corneas before and after lenticule implantation. Results: Keratoconus model was successfully reproduced. Tomographic analysis showed a significant inferiorly decentered corneal steepening with coherent stromal thinning. Model 2 reproduced better the curvature of real keratoconus. Lenticules type I implantation induced a homogeneous corneal thickening, type III produced higher thickening in the inferior half of the cornea. Type II determined a maximal peripheral pachymetric increase, with a gradual reduction toward the center, and type IV presented an asymmetric peripheral thickening. Topographic assessment showed a cone apex flattening in all cases, but it was significantly higher in types II and IV. Customized lenticules improved significantly corneal surface regularity regarding types I and II. Conclusions: The approach of customizing lenticules by increasing their asymmetry and tailoring the re-shaping effects, may improve SLAK outcomes in eccentric keratoconus.

Long-Term Evaluation of Patients with Neurotrophic Keratopathy Undergoing Staged Keratoplasty After Corneal Neurotization.

PURPOSE: Corneal neurotization (CN) is a novel, potentially curative surgical procedure for the treatment of neurothophic keratopathy (NK). Patients with severe NK can present with corneal opacification requiring optical keratoplasty, which would likely fail without a proper trophic support of corneal nerves in the recipient cornea. METHODS: This is a pilot study on 4 patients undergoing keratoplasty after CN. Pre- and postoperative data at 12, 24 months and at the last follow-up were collected for the examination of (i) best corrected visual acuity (BCVA), (ii) slit lamp examination and photograph acquisition with and without fluorescein staining, (iii) corneal aesthesiometry, (iv) in vivo confocal microscopy of the central cornea. Neurophysiological study of the corneal reflex before corneal graft and at last follow up was performed. RESULTS: Four female patients (47.25 ± 5.06 y.o.) underwent keratoplasty after CN (3 penetrating keratoplasty, 1 deep anterior lamellar keratoplasty). The mean interval between CN and keratoplasty was 22 (± 12) months. The mean graft survival time was 42 (± 25) months. Graft follow-up ranged from 72 to 132 months. At the final follow-up, BCVA was improved in 2 out of 4 patients. The mean corneal sensitivity was 11.9 ± 8.3 mm at last follow-up. In vivo confocal microscopy confirmed the presence of functioning nerves at the last follow-up in all patients. NK-related complications occurred in 3 eyes (2 persistent epithelial defect, 1 corneal melting). The former complication was successfully treated by autologous serum eye drops while the latter required repeated keratoplasty. CONCLUSIONS: Keratoplasty is a viable strategy to improve visual acuity in patients with corneal opacity who underwent CN for the treatment of NK. Even in the presence of functioning corneal nerves before keratoplasty, surgeons should be aware of the increased rate of NK-related complications that could require the need for repeated procedure.

Management of bilateral conjunctival squamous carcinoma following ocular cicatricial pemphigoid: A case report and review of literature.

The purpose of this study is to report a case of bilateral highly locally invasive conjunctival squamous neoplasia in the clinical setting of ocular cicatricial pemphigoid (OCP), and to review the available literature about this rare association.Case description: A man presented with chronic bilateral conjunctivitis and forniceal foreshortening. He had been previously diagnosed with OCP, and received proper therapy with systemic Dapsone and local steroids. After six months from treatment initiation, the patient complained of worsening symptoms and underwent two more biopsies, revealing a bilateral conjunctival squamous neoplasia. Conclusion: In rare cases, OCP can be associated with conjunctival squamous neoplasia. In case of suspected clinical modifications, it is important to make an early diagnosis by repeating several conjunctival biopsies or by performing less invasive diagnostic techniques (e.g. impression cytology of the ocular surface epithelium) to avoid unnecessary surgical damages.

10-year experience with lamellar keratoplasty for the surgical Management of Paediatric Corneal Diseases.

PURPOSE: To evaluate the outcomes of various lamellar keratoplasty techniques performed at our Institution in children aged 14 years or younger over the last decade. METHODS: This single-centre study reviewed 72 eyes that underwent lamellar keratoplasty for various indications. Deep anterior lamellar keratoplasty (DALK) was performed in 19 eyes, mushroom penetrating keratoplasty (PK) in 27 eyes and Descemet stripping automated endothelial keratoplasty (DSAEK) in 25 eyes. The main outcome measures included best spectacle-corrected visual acuity (BSCVA), complications and rate of graft failure which was defined as any graft requiring repeat transplantation. RESULTS: Best spectacle-corrected visual acuity (BSCVA) significantly improved after DALK, mushroom PK and DSAEK (all p < 0.05), with 50%, 60% and 56% of eyes reaching ≥20/40, respectively. Stromal rejection was observed in 1 eye (5.3%) after DALK, whilst endothelial rejection occurred in 1 eye after mushroom PK (3.7%) and 1 eye after DSAEK (4.0%). Overall survival was 100% after DALK (mean follow-up: 23.0 months), 92.8% after mushroom PK (mean follow-up: 42.3 months) and 96.0% after DSAEK (mean follow-up: 33.6 months). CONCLUSION: Deep anterior lamellar keratoplasty (DALK), mushroom PK and DSAEK offer good visual outcomes for children with corneal pathology, with low rates of immunological rejection and graft failure.

Impact of COVID-19 on surgical activities and personnel: lessons for the future.

BACKGROUND: COVID-19 pandemic has impacted professional, economic and social activities. In the surgical field, it has brought changes to operating activities, the organization of workforces, the protection measures for patients and personnel against possible intraoperative transmissions as well as training young surgeons. This study intends to assess the extent of this impact in our institution. METHODS: The patients operated on in nine Operating Units (OUs) in the period February 1 - March 31, 2020, with follow-ups on April 30, 2020, were evaluated both retrospectively and prospectively. Organizational, clinical and impact parameters on staff were evaluated. RESULTS: Of the 833 consecutive admitted patients, 742 were operated on, 705 of whom were recruited for the study. Compared to the same period in 2019 there was a decrease in the number of operations (742 compared to 1187), similar use of intensive care unit (ICU), a diagnostic activity only for symptomatic patients, heterogeneity in organizational behaviors, an impact on staff who highlighted concerns about getting sick or passing the infection on to others (87.64%) or their family members (75.14%). CONCLUSIONS: The present study made it possible to detect the need to make significant changes in the clinical, organizational and teaching fields, for which some operational proposals are suggested.

Epithelial and stromal remodelling following femtosecond laser-assisted stromal lenticule addition keratoplasty (SLAK) for keratoconus.

The purpose of this study was to evaluate corneal epithelium and stromal remodelling with anterior segment optical coherence tomography in patients who have undergone stromal lenticule addition keratoplasty (SLAK) for advanced keratoconus. This was a prospective non-comparative observational study. Fifteen eyes of 15 patients with advanced keratoconus underwent implantation with a cadaveric, donor negative meniscus-shaped intrastromal lenticule, produced with a femtosecond laser, into a stromal pocket dissected in the recipient cornea at a depth of 120 µm. Simulated keratometry, central corneal thickness (CTT), corneal thinnest point (CTP), central epithelial thickness (CET), central and peripheral lenticule thickness, anterior and posterior stromal thickness were measured. Regional central corneal epithelial thickness (CET) and variations in the inner annular area (IAT) and outer annular area (OAT) were also analysed. All parameters were measured preoperatively and 1, 3, and 6 months postoperatively. The average anterior Sim-k decreased from 59.63 ± 7.58 preoperatively to 57.19 ± 6.33 D 6 months postoperatively. CCT, CTP, CET, and OAT increased and IAT decreased significantly after 1 month. All parameters appeared unchanged at 6-months except that of OAT that further increased. Lenticule thickness was stable. In conclusion we observed that SLAK reshapes the cornea by central flattening with stromal thickening and epithelial thickness restoration.

In Vivo Confocal Microscopy of Stromal Lenticule Addition Keratoplasty for Advanced Keratoconus.

PURPOSE: To investigate the in vivo corneal microscopic changes after femtosecond laser-assisted stromal lenticule addition keratoplasty in keratoconus by means of in vivo confocal microscopy. METHODS: Patients affected by advanced keratoconus were included in the study. Negative meniscus-shaped stromal lenticules, produced with a femtosecond laser (VisuMax; Carl Zeiss Meditec) from eye bank corneas were transplanted into a stromal pocket dissected in the recipient cornea at a depth of 120 µm. In vivo confocal microscopy was performed during the 12-month follow-up to investigate changes of the corneal and lenticule structure. RESULTS: Ten patients were enrolled in the study. No changes of the dendritic cell population were documented during the follow-up period. Mild edema and stromal keratocyte activation gradually decreased during the first month. Subbasal nerve density returned to preoperative values after 6 months. Donor-recipient interfaces appeared hyperreflective but gradually improved over time with significantly reduced reflectivity after 3 months. No evidence of stromal inflammatory cell migration or matrix opacification was observed. Endothelial and keratocyte density remained stable over time. A variable degree of stromal radially distributed folds, not visible on biomicroscopy, was observed in the lenticule and in the posterior recipient stroma. CONCLUSIONS: Stromal lenticule addition keratoplasty produces transitory nerve plexus density reduction and minor inflammatory reaction that rapidly decreases during the first month. Donor-recipient interface reflectivity is comparable to a femtosecond laser refractive procedure with no sign of stromal opacification or stromal rejection in 1 year of follow-up. [J Refract Surg. 2020;36(8):544-550.].

Femtosecond Laser-Assisted Stromal Lenticule Addition Keratoplasty for the Treatment of Advanced Keratoconus: A Preliminary Study.

PURPOSE: To investigate the in vivo effect of a novel femtosecond laser-assisted procedure termed stromal lenticule addition keratoplasty for advanced keratoconus. METHODS: Ten patients with stage III and IV stable keratoconus were included. Negative meniscus-shaped stromal lenticules were produced from corneoscleral eye bank buttons with a refractive lenticule extraction procedure with a 500-kHz VisuMax femtosecond laser (Carl Zeiss Meditec, Jena, Germany). Recipient corneas underwent a modified femtosecond laser flap-cut procedure to produce an intrastromal pocket and lenticules were implanted. Patients were followed up for 6 months after surgery with determination of uncorrected (UDVA) and corrected (CDVA) distance visual acuity, subjective refraction and topographic corneal curvature changes, anterior segment optical coherence tomography (AS-OCT), and in vivo confocal microscopy. RESULTS: Comparison of preoperative and 6-month postoperative UDVA and CDVA showed statistically significant improvements (P = .024 and .007, respectively) from 1.58 ± 0.36 to 1.22 ± 0.37 and from 1.07 ± 0.17 to 0.70 ± 0.23 logMAR. Eight of 10 eyes showed an improvement in UDVA (P < .001) that ranged between one and three lines, whereas all but one eye presented improved CDVA. Corneal topography documented a decrease between preoperative and 6-month postoperative anterior mean curvature (AVG-K at 3 mm) and anterior Q values (P = .005). AS-OCT showed a significant increase in thickness of the central and mid-peripheral cornea produced by the lenticule implantation (P = .005). CONCLUSIONS: The stromal lenticule addition keratoplasty procedure was clinically efficient in improving the corneal shape and vision in patients with keratoconus. Negative meniscus-shaped lenticule addition induced a flattening of the cone while increasing corneal thickness. [J Refract Surg. 2018;34(1):36-44.].

Interference figures of polarimetric interferometry analysis of the human corneal stroma.

A rotating polarimetric 90°-cross linear-filter interferometry system was used to detect the morphological characteristics and features of interference patterns produced in in-vivo corneal stroma in healthy human corneas of 23 subjects. The characteristic corneal isogyres presenting with an evident cross-shaped pattern, grossly aligned with the fixation axis, were observed in all patients with centers within the pupillary dark area, impeding the exact determination of the center point. During the rotational scan in 78.3% of the eyes the cross-shaped pattern of the isogyre gradually separated to form two distinct hyperbolic arcs in opposite quadrants, reaching their maximal separation at 45 degrees with respect to angle of cross-shaped pattern formation. The corneal cross and hyperbolic-pattern repeated every 90° throughout the 360° rotational scan. While the interpretation of the isogyres presents particular difficulties, two summary parameters can be extracted for each cornea: the presence/orientation of a single or two dark areas in post-processed images and isochromes. However, the development of dedicated software for semi-quantitative analysis of these parameters and enantiomorphism may become available in the near future. The possible application of polarimetric interferometry in the field of both corneal pathologies and corneal surgery may be of great interest for clinical purposes.

In Vivo and Ex Vivo Evaluation of Inflammation and Apoptosis Induced after SMILE Procedures for Different Refractive Error Range.

PURPOSE: To detect corneal inflammation and apoptosis induced after small incision lenticule extraction (SMILE) at different refractive corrections for moderate to high values of myopia. METHODS: Fifty patients (50 eyes) suffering from medium to high myopia (spherical equivalent refraction from -3.75 to -10.00 diopters (D) with refractive astigmatism under -0.75 D) underwent SMILE in order to correct myopic error. In vivo evaluation was done by corneal confocal microscopy (IVCM) and ex vivo by immunohistochemistry. After surgery, all corneal lenticules were checked for regularity, entirety, and fixed in formalin for immunohistochemistry evaluation of apoptosis (TUNEL) and inflammation (CD11b) levels. Postoperative assessments took place during the first week and the first and third months after surgery. Patients returned for IVCM examination for analysis of the corneal stromal femtosecond laser treatment interfaces reflectivity. RESULTS: No correlation was observed between treated myopic refractive error and number of CD11b+ and TUNEL+ cell in all analyzed extracted lenticules. IVCM at 1 week and 1 month of follow-up showed numerous reflective particles at the laser treatment interface with a moderate light scattering. In semi-quantitative analysis of reflectivity intensity at the laser interfaces, a statistical difference was evident only between 1 week and 1 month (p = 0.0213). CONCLUSIONS: SMILE, as an innovative all-femto surgical procedure, results in a reduced tissue inflammation and apoptosis levels with a minimum tissue response, in terms of interface reflectivity, and there are no statistically significant differences among variable treated refractive error range.

Corneal cross-linking: intrastromal riboflavin concentration in iontophoresis-assisted imbibition versus traditional and transepithelial techniques.

PURPOSE: To determine differences in riboflavin concentration in the anterior, intermediate, and posterior stroma after 3 corneal cross-linking imbibition techniques (standard epithelial [epi]-off, epi-on, and iontophoresis-assisted administration) of 0.1% riboflavin. DESIGN: Experimental laboratory investigation of human cadaver corneas not suitable for transplantation. METHODS: Ten corneas underwent imbibition with epi-on (n = 3), epi-off (n = 3), iontophoresis (n = 3), and saline exposure (control; n = 1). Femtosecond laser was used to produce 3 8-mm discs of the superficial (0-150 µm), intermediate (150-300 µm), and deep stroma (>300 µm). Riboflavin concentration was measured with high-performance liquid chromatography. The main outcome measure was riboflavin concentration at the 3 evaluated depths. RESULTS: The overall stromal concentration of riboflavin was 34.1 ± 7.1 µg/g in epi-off, 7.2 ± 3.7 µg/g in epi-on, and 15.0 ± 5.1 µg/g in iontophoresis. The mean riboflavin content in the superficial slice in the epi-off group was about 2-fold greater than that of the iontophoresis group (50.5 ± 5.3 µg/g and 23.6 ± 2.5 µg/g, respectively) and 4-fold greater than that of the epi-on group (11.7 ± 3.3 µg/g). Similar differences among the 3 groups were observed for the intermediate and posterior stromal slices, presenting an evident reduction of riboflavin concentration with increasing depth in all groups. Slice depth-dependent decrease in riboflavin concentration was statistically significant (general linear model (GLM); F1,6 = 62.265, P < .001), as was the group-dependent variation (GLM; F2,6 = 20.268, P = .002) and the slice depth group interaction (GLM; F2,6 = 18.004, P = .002). CONCLUSIONS: Corneal cross-linking transepithelial iontophoresis imbibition yielded greater and deeper riboflavin saturation with respect to conventional epi-on, while maintaining the advantages of avoiding epithelial removal and shorter procedure time, but did not reach concentrations obtained with standard epi-off.