Purpose: A 6-month evaluation of the topographic and biomechanical changes induced by corneal collagen cross-linking (CXL) in keratoconic eyes using Pentacam and Corvis ST. Design: Longitudinal prospective case series. Methods: In this study, 67 eyes of 67 patients with progressive keratoconus (KCN) treated with “Epithelium-off” CXL were evaluated. Patients with stages 1 or 2 of KCN and a corneal thickness of at least 400 μm at the thinnest point were included. Standard ophthalmologic examinations were carried out for all patients. The topographic and biomechanical measurements of the cornea were obtained by Pentacam (Oculus Optikgeräte GmbH, Wetzlar, Germany) and Corvis ST (Oculus Optikgeräte GmbH, Wetzlar, Germany) preoperatively and 6-month postoperatively. Results: The mean age of the participants was 21.68 ± 4.23 years. There was significant difference in mean spherical equivalent (SE) before and 6 months after CXL. Uncorrected and best corrected visual acuity improved postoperatively, although not statistically significant. The mean and maximum keratometry showed a significant decrease 6 months after CXL (0.93 ± 0.38 D and 1.43 ± 0.62 D, respectively p < 0.001). Among Corvis ST parameters, first applanation length and velocity (AL1 and AV1) showed statistically significant changes. The radius at highest concavity changed significantly (0.13 ± 0.37 mm mean increase after CXL; p < 0.001). A significant increase was observed in stiffness parameter A1 (SP-A1; p < 0.001) and significant decreases were noted in integrated radius (IR) and deformation amplitude ratio (DAR; p < 0.001). Conclusion: Analyzing biomechanical changes after corneal cross-linking can provide basis for efficient KCN treatment. Corvis ST parameters demonstrated changes in corneal biomechanical characteristics indicative of stiffing after CXL.
outbreak has reached a critical state, and >200 countries worldwide have been affected. Iran was among the first countries that encountered the virus at a nationwide threat level. 1 The pandemic has imposed numerous burdens on society and the healthcare system.Medical specialties involve various examinations that may put patients and practitioners at risk of infection. Ophthalmic instruments may act as medium for viral transmission and ophthalmic healthcare facilities pose a risk of cross infection. 2,3 A recent review suggested that as coronaviruses are able to develop a wide range of ocular manifestations; thus, ophthalmologists should be cautious to prevent possible transmission through ocular tissue. 4 Cases of conjunctivitis have been reported in 6 In one report, 2 patients tested positive for SARS-CoV-2 using reverse-transcription polymerase chain reaction (rRT-PCR) assay of conjunctival secretions. 5 Moreover, the nasolacrimal duct may act as a pathway to transfer the virus from the eye to the nasopharynx. 7 Here, we address the prevention strategies employed against COVID-19 according to assessments of infection control experts and ophthalmologists, in Amiralmomenin Hospital a tertiary referral eye hospital in Guilan, Iran. To the best of our knowledge, this is the second report to describe the actions employed in an ophthalmology hospital setting. 8 At our institution preventive measures were applied in 3 main aspects outlined below. Patient management and screeningThe appointments of patients needing ophthalmic examinations (including those who had undergone corneal graft, cataract and vitreoretinal surgeries) were rearranged and other nonurgent appointments were deferred. Patients with a medical history of immune-suppression were appointed to be examined on a specific day. All elective ophthalmic surgeries and procedures were postponed, and patients were notified in advance; however, urgent ocular operations continued as normal.The daily number of patient referrals to the ophthalmic emergency unit decreased at an average of 58% compared to the previous month's daily average. This decrease was due to the hospital's relational unit advising local residents to seek ophthalmic care only when essential.Patients referring to the emergency unit were screened at the point of entry. The ophthalmic complaint was evaluated at triage by an eye-care nurse, and nonemergent conditions were requested to return for examination after the outbreak resolved. If the patient was physically capable, the companion would be asked to wait outside. All patients were asked about any related symptoms and underwent temperature screening. According to WHO definitions, 9 suspected COVID-19 cases would be isolated and transferred to a COVID-19 referral center for further evaluation.A safe distance (1.5 m) was assured between patients who were required to sit in the waiting room. Effort was made to maintain minimum waiting and consultation time. To avoid redundant visits to the hospital, patients who were managed in an outpatient setti...
Purpose: To evaluate the safety and efficacy of a bioengineered corneal implant using femtosecond laser–assisted anterior lamellar keratoplasty for superficial corneal opacities. Methods: Six eyes of 6 consecutive patients with superficial corneal stromal opacities involving <220 μm owing to various pathologies were included in the study. Preoperatively, all patients underwent anterior segment optical coherence tomography (Visante; Carl Zeiss Meditec AG) to evaluate the depth of the corneal opacity. All patients underwent sutureless femtosecond laser–assisted anterior lamellar keratoplasty using a bioengineered collagen corneal implant (linkcor). Visual indices, refraction, and keratometry were evaluated preoperatively and 12 months postoperatively. Results: Corrected distance visual acuity improved significantly in all patients (P = 0.02). A significant decrease was seen in refractive astigmatism postoperatively (P = 0.04). Flat keratometry reduced significantly 12 months after the intervention (P = 0.04). No intraoperative or early postoperative complications were noticed. All implants were fully covered by healthy epithelium within a month after the surgery and remained clear at follow-up visits. The results of this procedure remained stable throughout the follow-up period. In 1 patient, mild inferior collagen melting and epithelial defect formation occurred at 1-year follow-up. Despite frequent topical corticosteroid therapy the melting progressed, the collagen tissue was removed and the patient was treated accordingly with good visual outcomes. Conclusions: Femtosecond laser–assisted anterior lamellar keratoplasty with bioengineered corneal (linkcor) implantation is an effective treatment for improving vision quality in anterior stromal opacities. This procedure reduces the need for human donor tissue and avoids human donor-related and suturing complications.
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