Zicht op het venster

rede Afscheidsrede Prof. dr. G. van Rij hoogleraar Oogheelkunde Erasmus Universiteit Rotterdam, Uitgesproken 19 november 201

Change in corneal curvature induced by surgery

The first section deals with the mechanisms by which sutures, incisions and intracorneal contact lenses produce a change in corneal curvature. To clarify the mechanisms by which incisions and sutures produce astigmatism, we made incisions and placed sutures in the corneoscleral limbus of human eye bank eyes (chapter 2). The changes in corneal curvature were studied by central keratometry and by shadowgraph photography of the corneal contour. A radial corneal suture induces astigmatism by tissue compression. A radial anterior suture comprises more tissue on the outside than on the inside of the cornea. This moves the epithelial side of the cornea posteriorly towards the center of the globe. This posterior displacement decreased the sagittal depth of the cornea, so that the depth of the anterior chamber decreased slightly. The center of the cornea steepened in the meridian of the suture. This can be illustrated by holding a card between the thumb and first two fingers and applying pressure to make the card arch over the palm. When the forefinger of the other hand presses down near the arched card, this area moves toward the palm like limbal tissue near a suture and the arch of the central area of the card increases; resembling the steepening of the central cornea. With this theory we can understand the mechanism by which sutures produce corneal astigmatism after cataract surgery. Incisions in the anterior layers of the cornea weaken the mechanical stability. The intraocular pressure then causes the wound to gape arid outward bulging of the cornea. The central corneal curvature flattens. Corneal incisions are clinically used with radial keratotomy, an operation for the correction of myopia. It is one of the techniques of refractive corneal surgery. Refractive corneal surgery (chapter 3) constitutes of surgical techniques to change the corneal power so that the patient can see better without contact lenses or glasses. All these techniques are irreversible which led us to try and find a method that would be reversible. We found it to be possible to flatten the central corneal curvature of human eye bank eyes by radial interrupted nylon sutures (chapter 4)

Long-term results of corneal wedge resections for the correction of high astigmatism

Abstract We retrospectively evaluated 41 corneal wedge resections, performed for the correction of high astigmatism in 40 patients who were spectacle and contact lens intolerant. Keratometric astigmatism decreased from an average of 11.7 diopters (range 5 to 22.5 D) preoperatively to 3.5 diopters (range 0 to 10 D) postoperatively, representing a mean reduction of 8.2D (range 0 to 16.5), or 70%. The length of follow-up averaged 11 months. Twenty-five, 15 and 9 cases had a follow-up of at least 3, 5 and 10 years, respectively. In 16 cases the keratometry readings remained stable over the years. However, in 1 case of Fuchs' endothelial dystrophy (follow-up 13 years) and 5 cases of keratoconus (follow-up 3, 4, 12, 13 and 14 years) the astigmatism gradually increased during the various follow-up periods. In 3 other cases the astigmatism gradually decreased over the years. Corneal wedge resection is an effective technique for managing high corneal astigmatism. The results remain stable over the years except in some patients with keratoconus

Triple procedure; analysis of outcome, refraction, and intraocular lens power calculation

AIMS: A total of 97 triple procedures performed over a 6 year period were studied retrospectively to determine the best approach to calculate intraocular lens power. METHODS: The cases were divided into two diagnostic categories. RESULTS: After 1 year best corrected visual acuity was 20/40 or better in 37.5% of the cases of the 'modified group'. This group consists of patients with the diagnosis Fuchs' dystrophy, non-guttate endothelial dystrophy, and Reis-Buckler dystrophy. Analysis of visual acuity was made using logMAR. A final postoperative refraction within 2 dioptres of predicted refraction was achieved in 76.5% of patients in the modified group. CONCLUSION: In future, in the absence of a keratometry, a keratometry value of 7.49 mm will be used for calculation of the power of the implant as analysed in this study

Effect of macrophage depletion on immune effector mechanisms during corneal allograft rejection in rats

PURPOSE. In rats, corneal allograft rejection is delayed for at least 100 days by clodronate liposomes. These liposomes selectively deplete macrophages. To investigate the immunologic basis for absence of graft rejection in treated rats, the effect of these liposomes on the generation of cytotoxic T lymphocytes (CTLs) and antibody production after orthotopic corneal allotransplantation was determined. METHODS. Transplantations of corneal buttons from PVG rats were performed in AO rats. After surgery, one group received clodronate liposomes subconjunctivally at five time points, and the other group remained untreated. On postoperative day (POD) 3, 7, 12, or 17, rats were killed, the presence of CTLs was investigated at three different anatomic locations, and antibodies against donor antigens were tested. RESULTS. NO significant differences were found between the groups tested 3 and 7 days after surgery. But on POD 12 (the time of onset of rejection in the untreated group) and on POD 17, the CTL activities detected in the submandibular lymph nodes (P less than or equal to 0.008) and the spleen (P less than or equal to 0.009) were significantly less in the treated groups compared with the untreated groups. in the untreated groups complement-independent antibodies were present only on POD 17, whereas no antibodies were found in the treated rats. CONCLUSIONS. Local treatment with clodronate liposomes was shown to downregulate local and systemic CTL responses and to prevent the generation of antibodies. Local depletion of macrophages in the initiation phase of the immune response appears to lead to a less vigorous attack on the grafted tissue and therefore to promote graft survival

The impact of BNT162b2 mRNA vaccine on adaptive and innate immune responses

The mRNA-based BNT162b2 protects against severe disease and mortality caused by SARS-CoV-2 via induction of specific antibody and T-cell responses. Much less is known about its broad effects on immune responses against other pathogens. Here, we investigated the adaptive immune responses induced by BNT162b2 vaccination against various SARS-CoV-2 variants and its effects on the responsiveness of immune cells upon stimulation with heterologous stimuli. BNT162b2 vaccination induced effective humoral and cellular immunity against SARS-CoV-2 that started to wane after six months. We also observed long-term transcriptional changes in immune cells after vaccination. Additionally, vaccination with BNT162b2 modulated innate immune responses as measured by inflammatory cytokine production after stimulation - higher IL-1/IL-6 release and decreased IFN-α production. Altogether, these data expand our knowledge regarding the overall immunological effects of this new class of vaccines and underline the need for additional studies to elucidate their effects on both innate and adaptive immune responses.</p