Phospholipid Analyses of Rabbit Ocular Surface Tissues.

The tissues of the integument covering the ocular surface comprise a mucus membrane functioning as a protective physical barrier and has the ability to mount a defensive inflammatory response. Since lipid metabolism has a role in both of these functions, we studied normal membrane phospholipids (PL) of the cornea and bulbar conjunctiva to (1) determine baseline PL profiles of these tissues, (2) compare and contrast these individual PL metabolite profiles as well as groups of metabolites, and (3) describe pathway-specific metabolic interrelations among these tissues. Corneal and conjunctival tissue samples were isolated from rabbit eyes (n=30) and extracted with chloroform-methanol using a modified Folch procedure. 31P nuclear magnetic resonance spectroscopy was used to qualitatively and quantitatively measure tissue PL profiles. The cornea and conjunctiva, respectively, have the following PL composition (mole % of total detected phospholipid): phosphatidylglycerol (PG) - , 0.4; lysophosphatidylethanolamine 1.2, - ; phosphatidic acid - , 0.4; diPG (cardiolipin) 2.1, 3.5; unknown PL at the chemical shift of 0.13 δ 1.5, 0.9; ethanolamine plasmalogen 11.2, 13.0; phosphatidylethanolamine 11.5, 12.8; phosphatidylserine 8.9, 10.1; sphingomyelin 10.2, 10.7; lysophosphatidylcholine 0.9, 1.4; phosphatidylinositol 5.3, 5.3; phosphatidylcholine (PC) plasmalogen or alkylacylPC 2.2, 1.9; PC 45.1, 40.0. In addition, 28 PL metabolic indices were calculated from these data, which permitted pathway-specific lipid analyses. This study (1) establishes PL profiles of the two ocular tissues of the integument that cover the surface of the eye, (2) compares and contrasts indices comprised of ratios and combinations of PL, and (3) describes pathway-specific metabolic interrelations among these tissues to serve as baselines for studies involving the distribution of tissue phospholipids.

Main issues in deep anterior lamellar keratoplasty: A systematic narrative review.

Deep anterior lamellar keratoplasty (DALK) has emerged as a transformative approach in managing corneal pathologies, notably keratoconus (KC), providing a viable alternative to penetrating keratoplasty (PK). This systematic review explores the intricacies of DALK, comparing its preoperative, intraoperative, and postoperative considerations with PK. Extensive literature searches revealed a wealth of data regarding DALK's advantages and challenges, with an emphasis on graft survival, visual outcomes, and complications. In the preoperative phase, DALK showcases its versatility, catering to a wide spectrum of patients, including those with KC and ocular surface disorders. Intraoperatively, it offers innovative techniques to address emphysema, bubble formation, and Descemet's membrane perforation, all while maintaining a strong focus on patient-centered outcomes. Postoperatively, DALK's lower rejection rates and decreased complications underscore its potential superiority over PK, although unique challenges such as graft failure from nonimmunologic factors demand vigilant management. This comprehensive review not only serves as a valuable resource for ophthalmic surgeons but also sheds light on the evolving landscape of corneal transplantation, highlighting DALK's role as a transformative force in the field.

Biomechanical changes in keratoconus after customized stromal augmentation.

PURPOSE: To verify corneal biomechanical changes, poststromal augmentation using myopic small-incision lenticule extraction's (SMILEs) lenticules in advanced keratoconus (KCN) through Corvis ST (Oculus, Wetzlar, Germany). MATERIALS AND METHODS: A clinical trial enrolled 22 advanced KCN patients. We implanted lenticules exceeding 100 µ according to a nomogram and evaluated biomechanical factors through Corvis ST at 3-, 6-, and 24-month postimplantation. We examined parameters during the first applanation (A1), second applanation (A2), highest concavity (HC)/max concavity events, and Vinciguerra screening parameters, as recently established criteria derived from the ideal blend of diverse biomechanical and ocular factors and formulated through the application of logistic regression. Regression analyses explored relationships with age, mean keratometry value, thickness, sphere, cylinder, and best-corrected visual acuity. RESULTS: Patients were well matched for age, intraocular pressure, and central corneal thickness (CCT). The mean spherical equivalent decreased from -13.48 ± 2.86 Diopters (D) to -8.59 ± 2.17 D (P < 0.007), and mean keratometry decreased from 54.68 ± 2.77 D to 51.95 ± 2.21 D (P < 0.006). Significant increases were observed in HC time (HCT), Radius-central curvature radius at the HC state-, peak distance (PD) during HC state, CCT, first applanation time, and stiffness parameter (A1T and SP-A1), whereas HC deformation amplitude, maximum deformation amplitude ratio at 2 mm, Corvis Biomechanical Index (CBI), integrated radius (IR), second applanation deformation amplitude (A2DA), first applanation velocity and deflection amplitude (A1V and A1DeflA) significantly decreased postlenticule implantation. Multivariable regression revealed age positively correlated with SP-A1 (P = 0.003) and negatively with HC delta Arc length (P = 0.007). Mean K positively correlated with CCT (P = 0.05) and negatively with CBI (P = 0.032). Best-corrected visual acuity positively correlated with HCT (P = 0.044), and the cylinder positively correlated with PD (P = 0.05) and CCT (P = 0.05) whereas negatively with IR (P = 0.025). CONCLUSIONS: Stromal augmentation using myopic SMILE lenticules induces significant corneal biomechanical changes in KCN.

A comprehensive review on corneal crosslinking.

Corneal crosslinking (CXL) represents a paradigm shift in the management of corneal ectatic disorders. Before CXL was introduced, patients would need specialty contact lenses and possible corneal transplantation. CXL involves a biochemical reaction in which ultraviolet A light is used in conjunction with Riboflavin to form crosslinks in between corneal stromal collagen. This leads to strengthening and stabilizing of the collagen lamellae, resulting in mechanical stiffening of the cornea. Multiple protocols have been proposed including epithelium on versus off and varying light intensity and duration of treatment. All protocols appear to be safe and effective with few reported complications including infection, stromal haze, scarring, and endothelial toxicity. Overall, CXL has demonstrated to halt the progression of the disease clinically and in keratometry readings and improve the quality of life for patients. It is a minimally invasive, cost-effective procedure that can be performed in an outpatient setting with a fast recovery time and long-lasting results.

Review for special issue: Corneal lamellar surgery: Present outcomes and future perspectives.

Since the establishment of the first eye bank in the 1940s, their role has evolved to face new challenges. With the recent development of lamellar keratoplasties, eye banks play an even bigger role in the selection and preparation of donor tissues. The increasing number of keratoplasty techniques and the high demand for "ready-to-use" tissues are challenging eye banks to improve and develop new preparation techniques. Besides necessary examinations, new approaches of tissue analysis in eye banks allow a better/optimized selection of corneal tissues. These new challenges in tissue preservation, preparation, and selection are propelling eye banks into a new era of modern eye banking.

Microbial keratitis in Southern Malawi: a microbiological pilot study.

OBJECTIVE: Microbial keratitis (MK) is a significant cause of blindness in sub-Saharan Africa. We investigated the feasibility of using a novel corneal impression membrane (CIM) for obtaining and processing samples by culture, PCR and whole-genome sequencing (WGS) in patients presenting with suspected MK in Malawi. METHODS AND ANALYSIS: Samples were collected from patients presenting with suspected MK using a 12 mm diameter polytetrafluoroethylene CIM disc. Samples were processed using culture and PCR for Acanthamoeba, herpes simplex virus type 1 (HSV-1) and the bacterial 16S rRNA gene. Minimum inhibitory concentrations of isolates to eight antimicrobials were measured using susceptibility strips. WGS was used to characterise Staphylococcus aureus isolates. RESULTS: 71 eyes of 71 patients were included. The overall CIM isolation rate was 81.7% (58 positive samples from 71 participants). 69 (81.2%) of isolates were Gram-positive cocci. Coagulase-negative Staphylococcus 31.8% and Streptococcus species 14.1% were the most isolated bacteria. Seven (9.9%) participants were positive for HSV-1. Fungi and Acanthamoeba were not detected. Moxifloxacin and chloramphenicol offered the best coverage for both Gram-positive and Gram-negative isolates when susceptibility was determined using known antimicrobial first quartile concentrations and European Committee on Antimicrobial Susceptibility Testing breakpoints, respectively. WGS identified known virulence genes associated with S. aureus keratitis. CONCLUSIONS: In a resource-poor setting, a CIM can be used to safely sample the cornea in patients presenting with suspected MK, enabling identification of causative microorganisms by culture and PCR. Although the microbiological spectrum found was limited to the dry season, these preliminary results could be used to guide empirical treatment.

Replace or Regenerate? Diverse Approaches to Biomaterials for Treating Corneal Lesions.

The inner structures of the eye are protected by the cornea, which is a transparent membrane exposed to the external environment and subjected to the risk of lesions and diseases, sometimes resulting in impaired vision and blindness. Several eye pathologies can be treated with a keratoplasty, a surgical procedure aimed at replacing the cornea with tissues from human donors. Even though the success rate is high (up to 90% for the first graft in low-risk patients at 5-year follow-up), this approach is limited by the insufficient number of donors and several clinically relevant drawbacks. Alternatively, keratoprosthesis can be applied in an attempt to restore minimal functions of the cornea: For this reason, it is used only for high-risk patients. Recently, many biomaterials of both natural and synthetic origin have been developed as corneal substitutes to restore and replace diseased or injured corneas in low-risk patients. After illustrating the traditional clinical approaches, the present paper aims to review the most innovative solutions that have been recently proposed to regenerate the cornea, avoiding the use of donor tissues. Finally, innovative approaches to biological tissue 3D printing and xenotransplantation will be mentioned.

[Impact of the ratio between graft and host corneal size on immune rejection, re-bubbling rate and postoperative endothelial cell loss in 457 eyes after Descemet membrane endothelial keratoplasty (DMEK)]. / Einfluss des Verhältnisses von Transplantatgröße zu Hornhautgröße auf Immunreaktion, Re-Bubbling-Rate und postoperativen Endothelzellverlust bei 457 Augen nach Descemet-Membrane-Endothelial-Keratoplastik (DMEK).

BACKGROUND: The aim of this study was to assess the impact of the ratio between the graft and host corneal size (RGH) on postoperative complications, such as immune reactions, re-bubbling rate and endothelial cell loss (ECL) after Descemet membrane endothelial keratoplasty (DMEK). PATIENTS AND METHODS: Retrospectively, 457 patient eyes were included which had undergone surgery between 2016 and 2019 in the Department of Ophthalmology, Saarland University Medical Center in Homburg/Saar using DMEK or triple DMEK, diagnosed as Fuchs' endothelial dystrophy (n = 431), pseudophakic bullous keratopathy (n = 9) and others (n = 17). The follow-up period extended until the end of 2020. Main outcome measures included immune reaction (IR), re-bubbling rate and the postoperative endothelial cell loss (ECL) at 6 weeks, 6 months and 12 months and whether these measures depended on the RGH. RESULTS: The RGH in this study ranged from 0.35 to 0.62 (0.46 ± 0.04). There were 33 (7.2%) postoperative IRs (DMEK n = 25; triple DMEK n = 8). The average RGH without IR (0.46 ± 0.04) was significantly (p = 0.038) smaller than in the group with IR (0.47 ± 0.05). Re-bubbling was necessary in 159 of 457 (34.8%) patient eyes. The RGH in patient eyes with re-bubbling (0.47 ± 0.04) was significantly (p = 0.014) higher than that in eyes without re-bubbling (0.45 ± 0.04). The mean preoperative endothelial cell count (ECD) was 2603 ± 251 cells/mm2 (min: 2161, max: 3500 cells/mm2). It was shown that a larger RGH had no positive influence on endothelial cell loss (r = 0.001; p = 0.974). CONCLUSION: Our results suggest that a larger graft diameter compared to host corneal size is associated with an increased rate of immune reactions and a higher re-bubbling rate after DMEK. Otherwise, a larger RGH had no positive influence on endothelial cell loss after DMEK. Accordingly, the graft size for DMEK should not be unnecessarily large, especially in eyes with Fuchs' endothelial dystrophy.

Elucidating the mechanism of corneal epithelial cell repair: unraveling the impact of growth factors.

The repair mechanism for corneal epithelial cell injuries encompasses migration, proliferation, and differentiation of corneal epithelial cells, and extracellular matrix remodeling of the stromal structural integrity. Furthermore, it involves the consequential impact of corneal limbal stem cells (LSCs). In recent years, as our comprehension of the mediating mechanisms underlying corneal epithelial injury repair has advanced, it has become increasingly apparent that growth factors play a pivotal role in this intricate process. These growth factors actively contribute to the restoration of corneal epithelial injuries by orchestrating responses and facilitating specific interactions at targeted sites. This article systematically summarizes the role of growth factors in corneal epithelial cell injury repair by searching relevant literature in recent years, and explores the limitations of current literature search, providing a certain scientific basis for subsequent basic research and clinical applications.

Evidence for persistent UV-induced DNA damage and altered DNA damage response in xeroderma pigmentosa patient corneas.

Xeroderma pigmentosum (XP) is a rare genetic disorder characterized by injury to the ocular surface due to exposure to ultraviolet (UV) radiation. UV-induced damage in the cells leads to the formation of cyclobutane pyrimidine dimers (CPDs) and 6-4 pyrimidine-pyrimidone photoproducts that are repaired by the NER (Nucleotide Excision Repair) pathway. Mutations in the genes coding for NER proteins, as reported in XP patients, would lead to sub-optimal damage repair resulting in clinical signs varying from photo-keratitis to cancerous lesions on the ocular surface. Here, we aimed to provide evidence for the accumulation of DNA damage and activation of DNA repair pathway proteins in the corneal cells of patients with XP. Corneal buttons of patients who underwent penetrating keratoplasty were stained to quantify DNA damage and the presence of activated DNA damage response proteins (DDR) using specific antibodies. Positive staining for pH2A.X and thymidine dimers confirmed the presence of DNA damage in the corneal cells. Positive cells were found in both control corneas and XP samples however, unlike normal tissues, positive cells were found in all cell layers of XP samples indicating that these cells were sensitive to very low levels of UV. pH2A.X-positive cells were significantly more in XP corneas(p<0.05) indicating the presence of double strand breaks in these tissues. A positive expression of phosphorylated-forms of DDR proteins was noted in XP corneas (unlike controls) such as ataxia telangiectasia mutated/Rad-3 related proteins (ATM/ATR), breast cancer-1 and checkpoint kinases-1 and -2. Nuclear localization of XPA was noted in XP samples which co-localized (calculated using Pearson's correlation) with pATM (0.9±0.007) and pATR (0.6±0.053). The increased presence of these in the nucleus confirms that unresolved DNA damage was accumulating in these cells thereby leading to prolonged activation of the damage response proteins. An increase in pp53 and TUNEL positive cells in the XP corneas indicated cell death likely driven by the p53 pathway. For comparison, cultured normal corneal epithelial cells were exposed to UV-radiation and stained for DDR proteins at 3, 6 and 24 hours after irradiation to quantify the time taken by cells with intact DDR pathway to repair damage. These cells, when exposed to UV showed nuclear translocation of DDR proteins at 3 and 6 hours which reduced significantly by 24 hours confirming that the damaged DNA was being actively repaired leading to cell survival. The persistent presence of the DDR proteins in XP corneas indicates that damage is being actively recognized and DNA replication is stalled, thereby causing accumulation of damaged DNA leading to cell death, which would explain the cancer incidence and cell loss reported in these patients.

Design of a new 3D printed all-in-one magnetic smartphone adapter for fundus and anterior segment imaging.

PURPOSE: To describe and validate a 3D-printed adapter tool which could be used with either a slit lamp or a condensing lens, interchangeable between devices through magnetic fastening, in order to provide physicians a quick, easy and effective method of obtaining clinical photos. MATERIALS AND METHODS: Three specialists, with at least 4-year experience in ophthalmology, gave a rate of image quality obtained by our device and the diagnostic confidence grade. The 3 specialists conducted each 13 or 14 examinations with the smartphone and magnetic adapter. At the end of evaluation, they rated with the Likert scale the ease of use of the device in obtaining clinical images of the anterior segment and ocular fundus respectively. RESULTS: Data of quality perception and confidence demonstrated high values not dissimilar to the "de visu" eye examination. Moreover the instrument we designed turned out to be very user friendly. CONCLUSION: Our adapter coupled with a modern smartphone was able to obtain 4k images and videos of anterior segment, central and peripheral fundus, in an easy and inexpensive way.

Views of admitted palliative care patients and their clinicians on corneal donation discussions: a qualitative content analysis of semi-structured interviews.

BACKGROUND: There is a severe shortage of corneas for donation, globally, for transplantation and research purposes. One group of individuals who could potentially be donors are those who die within the inpatient palliative care unit. The aim of the study was to understand clinician and patient perceptions of corneal donations and discussion of donation in palliative care units. METHODS: A qualitative design was utilised with data collected through semi-structured interviews and analysed using qualitative content analysis. A total of 46 interviews were undertaken involving inpatient palliative care unit patients (19) and clinicians (27) in three major inpatient palliative care units in South Australia. RESULTS: Very few patient participants reported being asked about corneal donations during their time in palliative care. Most inpatient palliative care unit clinicians did not raise the topic as they felt other areas of care took precedence. Inpatient palliative care unit patients thought if inpatient palliative care unit clinicians did not raise the topic, then it was not important. There were some differences between patient and clinician views, such as preference about who raises the possibility of donation and when the discussion might occur. CONCLUSIONS: Findings suggest that patients are receptive to discussing corneal donations, but clinicians are not initiating these. This is a missed opportunity for donors and potential recipients. We recommend that clinicians routinely discuss eye donation as part of palliative care.

Single cell analysis of short-term dry eye induced changes in cornea immune cell populations.

Background: Dry eye causes corneal inflammation, epitheliopathy and sensorineural changes. This study evaluates the hypothesis that dry eye alters the percentages and transcriptional profiles of immune cell populations in the cornea. Methods: Desiccating stress (DS) induced dry eye was created by pharmacologic suppression of tear secretion and exposure to drafty low humidity environment. Expression profiling of corneal immune cells was performed by single-cell RNA sequencing (scRNA-seq). Cell differentiation trajectories and cell fate were modeled through RNA velocity analysis. Confocal microscopy was used to immunodetect corneal immune cells. Irritation response to topical neurostimulants was assessed. Results: Twelve corneal immune cell populations based on their transcriptional profiles were identified at baseline and consist of monocytes, resident (rMP) and MMP12/13 high macrophages, dendritic cells (cDC2), neutrophils, mast cells, pre T/B cells, and innate (γDT, ILC2, NK) and conventional T and B lymphocytes. T cells and resident macrophages (rMP) were the largest populations in the normal cornea comprising 18.6 and 18.2 percent, respectively. rMP increased to 55.2% of cells after 5 days of DS. Significant changes in expression of 1,365 genes (adj p < 0.0001) were noted in rMP with increases in cytokines and chemokines (Tnf, Cxcl1, Ccl12, Il1rn), inflammatory markers (Vcam, Adam17, Junb), the TAM receptor (Mertk), and decreases in complement and MHCII genes. A differentiation trajectory from monocytes to terminal state rMP was found. Phagocytosis, C-type lectin receptor signaling, NF-kappa B signaling and Toll-like receptor signaling were among the pathways with enhanced activity in these cells. The percentage of MRC1+ rMPs increased in the cornea and they were observed in the basal epithelium adjacent to epithelial nerve plexus. Concentration of the chemokine CXCL1 increased in the cornea and it heightened irritation/pain responses to topically applied hypertonic saline. Conclusion: These findings indicate that DS recruits monocytes that differentiate to macrophages with increased expression of inflammation associated genes. The proximity of these macrophages to cornea nerves and their expression of neurosensitizers suggests they contribute to the corneal sensorineural changes in dry eye.

Robust and accurate corneal interfaces segmentation in 2D and 3D OCT images.

Segmentation of corneal layer interfaces in optical coherence tomography (OCT) images is important for diagnostic and surgical purposes, while manual segmentation is a time-consuming and tedious process. This paper presents a novel technique for the automatic segmentation of corneal layer interfaces using customized initial layer estimation and a gradient-based segmentation method. The proposed method was also extended to three-dimensional OCT images. Validation was performed on two corneal datasets, one with 37 B-scan images of healthy human eyes and the other with a 3D volume scan of a porcine eye. The approach showed robustness in extracting different layer boundaries in the low-SNR region with lower computational cost but higher accuracy compared to existing techniques. It achieved segmentation errors below 2.1 pixels for both the anterior and posterior layer boundaries in terms of mean unsigned surface positioning error for the first dataset and 2.6 pixels (5.2 µm) for segmenting all three layers that can be resolved in the second dataset. On average, it takes 0.7 and 0.4 seconds to process a cross-sectional B-scan image for datasets one and two, respectively. Our comparative study also showed that it outperforms state-of-the-art methods for quantifying layer interfaces in terms of accuracy and time efficiency.

Correlation Between the Cost and Safety of Corneal Graft Types.

Background Corneal diseases are the fourth most common cause of blindness worldwide. In the majority of these diseases, vision reduction is reversible and can be restored to a large extent by replacing the cornea through specific surgery and, in particular, transplantation. In Greece, due to a lack of organized eye banks as well as donors, the grafts intended for corneal transplantation usually come from eye banks abroad. This study focuses on the dynamics of cost versus value in the decision-making process for the procurement of corneal grafts, ultimately investigating the safety that the procured grafts provide to patients. Methodology A total of 267 patients with severe vision problems who underwent 301 corneal and amniotic membrane transplants from years 2020 to 2023 at the Transplant Unit of the Athens General Hospital "Georgios Gennimatas" were included in this study. All patients who were deemed appropriate to undergo corneal transplant operations, the diagnosis that led to the specific surgery, and other relevant data were recorded and evaluated. Results There was no significant difference in the ratio between males and females (51.3% male and 48.7% female). The mean age of the patients was 66.5 years (SD = 13.7 years). Graft problems were faced by 13.9% of the patients, with the amniotic membrane by 1.5% (in the total number of surgical operations) and both eyes by 4.5% of patients. The majority of the patients had undergone only one surgery (88.8%). Reoperation was needed in 14% of the cases, and 7.6% of the cases were surgeries that occurred due to graft rejection or non-functioning grafts from surgeries performed at another hospital or clinic. In the majority of surgeries (60.8%), a Descemet's stripping automated endothelial keratoplasty graft was used. The mean cost was 3,167 euro (SD = 960.3 euro). Furthermore, in 35.8% of the surgeries, the graft was preserved with amphotericin. Conclusions The present study draws useful conclusions about the effectiveness of surgical interventions through the correlation of cost and safety of the grafts that are approved and finally used in corneal transplants, as well as the submission of proposals to improve the procedures and lead to patient benefits.

Modified sutureless and glue-free method versus conventional sutures for conjunctival autograft fixation in primary pterygium surgery: a systematic review and meta-analysis.

BACKGROUND: Pterygium is a common ocular surface disorder that requires surgical intervention for treatment. Conjunctival autografts are preferred over simple excision due to lower recurrence rates. This systematic review and meta-analysis compared the modified sutureless glue-free (MSGF) method with conventional sutures (CS) for conjunctival autograft fixation in primary pterygium surgery. METHODS: A comprehensive search was conducted in MEDLINE, Embase, CENTRAL, Google Scholar and ClinicalTrials.gov for randomised controlled trials (RCTs) comparing MSGF and CS conjunctival autografts. Outcome measures included operation time, recurrence and postoperative complications. Standardised mean difference (SMD) and risk ratio (RR) were used for continuous and dichotomous outcomes, respectively. RESULTS: 11 RCTs involving 833 participants were included. The analysis revealed that MSGF had a significantly shorter operation time compared with CS (SMD -3.704, 95% CI -5.122 to -2.287, p<0.001). CS was associated with a higher risk of foreign body sensation (RR 0.22, 95% CI 0.06 to 0.74, p=0.01). MSGF was associated with a higher risk of graft dehiscence (RR 9.01, 95% CI 2.74 to 29.68, p=0.000) and graft retraction (RR 2.37, 95% CI 1.17 to 4.77, p=0.02). No significant differences were found in recurrence, graft haemorrhage, granuloma, Dellen and conjunctival oedema. CONCLUSION: Using the MSGF technique in conjunctival autograft fixation for pterygium surgery reduces operation time by relying solely on the patient's blood for fixation. However, it increases the risk of graft dehiscence and retraction. However, CS is linked to a higher likelihood of experiencing foreign body sensations. Understanding the learning curve and surgeon familiarity with novel techniques is crucial for optimising patient care and surgical outcomes, while individualised decision-making is necessary considering the advantages and disadvantages of each approach. Further research is warranted to minimise complications and optimise surgical outcomes.

Femtosecond laser-assisted astigmatic keratotomy versus toric IOL implantation for correcting astigmatism in cataract patients: a systematic review and meta-analysis with trial sequential analysis.

AIMS: To compare the refractive and visual outcomes of femtosecond laser-assisted astigmatic keratotomy (FSAK) and toric intraocular lens (IOL) implantation for correcting astigmatism in cataract patients. METHODS: Studies were retrieved from the Ovid-Medline, EMBASE, Cochrane Central Register of Controlled Trials and Scopus which compared FSAK and toric IOL for astigmatism correction in cataract patients. Outcome measures included postoperative refractive cylinder, correction index, uncorrected distance visual acuity (UDVA), the proportion of patients achieving a residual refractive cylinder of 1.00 dioptre or less, target-induced astigmatism (TIA) and surgically induced astigmatism (SIA). The trial sequential analysis (TSA) was used to collect firm evidence supporting our conclusion. RESULTS: 9 studies encompassing 590 participants were analysed. The meta-analysis revealed that toric IOLs could result in less postoperative refractive cylinder and provide better UDVA compared with FSAK. The TSA disclosed strong evidence of lower postoperative refractive cylinder in the toric IOL group compared with that of the FSAK group. FSAK showed a smaller correction index and lower mean TIA and SIA compared with toric IOLs. CONCLUSIONS: For cataract patients, both FSAK and toric IOLs are effective methods for correcting astigmatism. However, toric IOLs offer less postoperative astigmatism and result in better postoperative UDVA compared with FSAK. In vector analysis of astigmatism, toric IOLs can also produce higher TIA and SIA. Additionally, neither method is associated with severe untreatable complications. Therefore, the conclusion is that toric IOLs are the preferred choice for astigmatism correction in cataract patients and FSAK serves as a viable alternative when toric IOLs are contraindicated.

Validation of the Reichert® Tono-Vera® Vet rebound tonometer in normal ex vivo canine eyes.

OBJECTIVE: To determine the accuracy of the Reichert® Tono-Vera® Vet rebound tonometer for canine intraocular pressure (IOP) measurement. ANIMALS STUDIED: Five normal canine ex vivo globes. PROCEDURES: The anterior chambers of five freshly enucleated normal canine eyes were cannulated and connected to a reservoir of Plasma-Lyte A and a manometer. Starting at a manometric IOP of 5 mmHg, the pressure was progressively increased to 80 mmHg by raising the reservoir. Triplicate IOP measurements were taken with the Tono-Vera® Vet from the central cornea using the dog setting and compared to the manometric pressure by linear regression analysis and Bland-Altman plots. RESULTS: There was a strong positive linear regression trend when comparing central corneal Tono-Vera® Vet IOPs to manometric pressures (r2 = .99) with solid agreement between the two methods. Compared to manometric IOPs, the Tono-Vera® Vet underestimated IOPs at higher pressures ≥70 mmHg. CONCLUSIONS: Measurement of IOPs from the central cornea with the Tono-Vera® Vet provided accurate results over a large range in normal canine globes compared to direct manometry. The mild to moderate underestimation of IOPs at high pressures was not considered clinically relevant.

Evaluation of the results of contact lens assisted corneal cross-linking treatment in keratoconus patients with thin corneas.

PURPOSE: We aimed to compare the efficacy and safety of accelerated contact lens-assisted cross-linking (CA-CXL) with Lotrafilcon B and Comfilcon A lenses in keratoconus (KC) patients with thin corneas. STUDY DESIGN: Retrospective, single-center study. MATERIALS AND METHODS: We retrospectively included 51 eyes of 39 KC patients with corneal thickness <400µm after epithelial scraping (Epi-off), who underwent accelerated CA-CXL treatment with Lotrafilcon B (n=20) and Comfilcon A (n=31). Uncorrected and corrected distance visual acuity (UDVA and CDVA), manifest refraction values, corneal topographic data and endothelial cell density were recorded at preoperative and postoperative 1st, 3rd and 6th month controls. RESULTS: CDVA in the Comfilcon A group was higher than CDVA before surgery at 6 months postoperatively (p<0.001). When the two lenses were compared, CDVA was found to be significantly higher in the Lotrafilcon B group in the preoperative, postoperative 1st month and 3rd month values, but there was no significant difference between the postoperative 6th month values (p=0.028, p=0.018, p=0.044, p=0.181, respectively). The maximum keratometry (Kmax) value at the 6th month after surgery in the Comfilcon A group was significantly lower than in the Lotrafilcon B group (p=0,009). There was no significant difference between the endothelial cell density values between the groups (p=0.623, p=0.609, p=0.794, p=0.458, respectively). There was no significant difference between the progression, regression, and stability rates of the two groups (p=0.714). CONCLUSIONS: Accelerated CA-CXL with Lotrafilcon B and Comfilcon A silicone hydrogel lenses is a safe and effective method to stop progression in patients with thin corneas.

Determination of progressive endothelial cell loss after posterior chamber phakic intraocular lens implantation.

Comments about endothelial cell loss after posterior chamber phakic intraocular lens are provided, with a particular emphasis on the importance of determining progressive postoperative cell density reduction, excluding that related to surgical trauma.