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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

Abdominal aortic aneurysm is associated with a variant in low-density lipoprotein receptor-related protein 1

Abdominal aortic aneurysm (AAA) is a common cause of morbidity and mortality and has a significant heritability. We carried out a genome-wide association discovery study of 1866 patients with AAA and 5435 controls and replication of promising signals (lead SNP with a p value < 1 × 10-5) in 2871 additional cases and 32,687 controls and performed further follow-up in 1491 AAA and 11,060 controls. In the discovery study, nine loci demonstrated association with AAA (p < 1 × 10-5). In the replication sample, the lead SNP at one of these loci, rs1466535, located within intron 1 of low-density-lipoprotein receptor-related protein 1 (LRP1) demonstrated significant association (p = 0.0042). We confirmed the association of rs1466535 and AAA in our follow-up study (p = 0.035). In a combined analysis (6228 AAA and 49182 controls), rs1466535 had a consistent effect size and direction in all sample sets (combined p = 4.52 × 10-10, odds ratio 1.15 [1.10-1.21]). No associations were seen for either rs1466535 or the 12q13.3 locus in independent association studies of coronary artery disease, blood pressure, diabetes, or hyperlipidaemia, suggesting that this locus is specific to AAA. Gene-expression studies demonstrated a trend toward increased LRP1 expression for the rs1466535 CC genotype in arterial tissues; there was a significant (p = 0.029) 1.19-fold (1.04-1.36) increase in LRP1 expression in CC homozygotes compared to TT homozygotes in aortic adventitia. Functional studies demonstrated that rs1466535 might alter a SREBP-1 binding site and influence enhancer activity at the locus. In conclusion, this study has identified a biologically plausible genetic variant associated specifically with AAA, and we suggest that this variant has a possible functional role in LRP1 expression

Shared Genetic Risk Factors of Intracranial, Abdominal, and Thoracic Aneurysms

Background-Intracranial aneurysms (IAs), abdominal aortic aneurysms (AAAs), and thoracic aortic aneurysms (TAAs) all have a familial predisposition. Given that aneurysm types are known to co-occur, we hypothesized that there may be shared genetic risk factors for IAs, AAAs, and TAAs. Methods and Results-We performed a mega-analysis of 1000 Genomes Project-imputed genome-wide association study (GWAS) data of 4 previously published aneurysm cohorts: 2 IA cohorts (in total 1516 cases, 4305 controls), 1 AAA cohort (818 cases, 3004 controls), and 1 TAA cohort (760 cases, 2212 controls), and observed associations of 4 known IA, AAA, and/or TAA risk loci (9p21, 18q11, 15q21, and 2q33) with consistent effect directions in all 4 cohorts. We calculated polygenic scores based on IA-, AAA-, and TAA-associated SNPs and tested these scores for association to case-control status in the other aneurysm cohorts; this revealed no shared polygenic effects. Similarly, linkage disequilibrium-score regression analyses did not show significant correlations between any pair of aneurysm subtypes. Last, we evaluated the evidence for 14 previously published aneurysm risk single-nucleotide polymorphisms through collaboration in extended aneurysm cohorts, with a total of 6548 cases and 16 843 controls (IA) and 4391 cases and 37 904 controls (AAA), and found nominally significant associations for IA risk locus 18q11 near RBBP8 to AAA (odds ratio [OR]= 1.11; P=4.1 x 10(-5)) and for TAA risk locus 15q21 near FBN1 to AAA (OR=1.07; P=1.1 x 10(-3)). Conclusions-Although there was no evidence for polygenic overlap between IAs, AAAs, and TAAs, we found nominally significant effects of two established risk loci for IAs and TAAs in AAAs. These two loci will require further replication.Peer reviewe

Penetrating Keratoplasty Surgery [3] (multiple letters)

No abstract available

INTRACORNEAL AND SCLERAL CYST FOLLOWING CATARACT EXTRACTION

Background. A six-year-old boy presented with a large progressive intracorneal and scleral cyst. Two years before, bilateral cataract surgery through a 6.5-mm corneal incision was performed elsewhere.Methods. The posterior wall of the cyst could be excised, as well as the anterior wall in the sclera. Upon histo-pathology the cyst wall was lined by epithelium. The epithelial cells of the anterior side in the cornea were removed with a curette and a corpus alienum drill. Three and a half years after removal of the cyst, there was no recurrence. Visual acuity was 0.8. Conclusions. An intracorneal and scleral inclusion cyst was successfully removed by surgical excision and the removal of epithelial cells by a curette and a corpus alienum drill.</p

MORPHOMETRIC ANALYSIS OF THE CORNEAL ENDOTHELIUM WITH 3 DIFFERENT SPECULAR MICROSCOPES

The morphometry of the central corneal endothelium of 10 eyes in 10 subjects was analyzed with three different specular microscopes. Computer-assisted analysis was performed with only two microscopes (Zeiss and Keeler Konan sp 3300) because the third microscope (Topcon sp 1000) could not be adapted to our computerized system. With this Topcon microscope a grid with standard densities was used to compare the images with, in addition, we also performed manual cell counting on the same Topcon images. The coefficient of variation of the cell analysis of three different images per cornea with the four methods varied between 3.4 and 4.7 percent. One-way analysis of variance showed a significant difference between the Zeiss and the other microscopes. So only the Keeler Konan and the Topcon microscopes could be used interchangeably, The computerized image analysis permitted also an evaluation of the hexagonality. The results of polygonality were not significantly different between the Zeiss and the Keeler Konan. For clinical purposes the Topcon specular microscope is more advantageous than the other two methods, since it is the most rapid way to record and analyze specular images. But for more precise measurements an image processing system is indispensable