Iris from Iridectomy Used as Spacer underneath the Scleral Flap: The Iridenflip Trabeculectomy Technique

Purpose. We describe a modified trabeculectomy technique in which the iris is used to prevent fibrosis of the scleral flap. Material and Methods. A retrospective case series of patients with medically uncontrolled open angle glaucoma underwent trabeculectomy. Instead of performing a classical iridectomy, the iris was used as spacer underneath the scleral flap. Postoperative management was identical to classical trabeculectomy, with suture removal and needling if necessary. Five of the patients underwent simultaneous phacoemulsification through a separate temporal corneal incision. Patients should have two-year follow-up. Results. Data of ten patients were analysed, two had a previous failed trabeculectomy, two had LTP, and one had a corneal transplantation. In 3 patients MMC 0,1 mg/mL was used. After one and two years mean IOP was, respectively, 13,1 and 12,1 mmHg. IOP ≤ 16 mmHg was reached in 90% of patients without pressure lowering medication. No major complications were seen; no abnormal inflammatory reaction and no deformation or dislocation of the pupil occurred. Conclusion. By using the iris from the iridectomy as spacer under the scleral flap, fibrosis of the scleral flap is no longer possible. This iridenflip trabeculectomy technique gives an excellent complete success rate (IOP ≤ 16 mmHg) of 90%. A larger study is currently being done

Femtosecond laser-assisted cataract surgeries reported to the European Registry of Quality Outcomes for Cataract and Refractive Surgery : baseline characteristics, surgical procedure, and outcomes

Purpose To describe a large cohort of femtosecond laser-assisted cataract surgeries in terms of baseline characteristics and the related outcomes. Setting Eighteen cataract surgery clinics in 9 European countries and Australia. Design Prospective multicenter case series. Methods Data on consecutive eyes having femtosecond laser-assisted cataract surgery in the participating clinics were entered in the European Registry of Quality Outcomes for Cataract and Refractive Surgery (EUREQUO). A trained registry manager in each clinic was responsible for valid reporting to the EUREQUO. Demographics, preoperative corrected distance visual acuity (CDVA), risk factors, type of surgery, type of intraocular lens, visual outcomes, refractive outcomes, and complications were reported. Results Complete data were available for 3379 cases. The mean age was 64.4 years ± 10.9 (SD) and 57.8% (95% confidence interval [CI], 56.1-59.5) of the patients were women. A surgical complication was reported in 2.9% of all cases (95% CI, 2.4-3.5). The mean postoperative CDVA was 0.04 ± 0.15. logarithm of the minimum angle of resolution. A biometry prediction error (spherical equivalent) was within ±0.5 diopter in 71.8% (95% CI, 70.3-73.3) of all surgeries. Postoperative complications were reported in 3.3% (95% CI, 2.7-4.0). Patients with good preoperative CDVA had the best visual and refractive outcomes; patients with poor preoperative visual acuity had poorer outcomes. Conclusions The visual and refractive outcomes of femtosecond laser-assisted cataract surgery were favorable compared with manual phacoemulsification. The outcomes were highly influenced by the preoperative visual acuity, but all preoperative CDVA groups had acceptable outcomes

Human Tears Reveal Insights into Corneal Neovascularization

Corneal neovascularization results from the encroachment of blood vessels from the surrounding conjunctiva onto the normally avascular cornea. The aim of this study is to identify factors in human tears that are involved in development and/or maintenance of corneal neovascularization in humans. This could allow development of diagnostic tools for monitoring corneal neovascularization and combination monoclonal antibody therapies for its treatment. In an observational case-control study we enrolled a total of 12 patients with corneal neovascularization and 10 healthy volunteers. Basal tears along with reflex tears from the inferior fornix, superior fornix and using a corneal bath were collected along with blood serum samples. From all patients, ocular surface photographs were taken. Concentrations of the pro-angiogenic cytokines interleukin (IL)-6, IL-8, Vascular Endothelial Growth Factor (VEGF), Monocyte Chemoattractant Protein 1 (MCP-1) and Fas Ligand (FasL) were determined in blood and tear samples using a flow cytometric multiplex assay. Our results show that the concentration of pro-angiogenic cytokines in human tears are significantly higher compared to their concentrations in serum, with highest levels found in basal tears. Interestingly, we could detect a significantly higher concentration of IL- 6, IL-8 and VEGF in localized corneal tears of patients with neovascularized corneas when compared to the control group. This is the first study of its kind demonstrating a significant difference of defined factors in tears from patients with neovascularized corneas as compared to healthy controls. These results provide the basis for future research using animal models to further substantiate the role of these cytokines in the establishment and maintenance of corneal neovascularization

Anesthesia techniques and the risk of complications as reflected in the European Registry of Quality Outcomes for Cataract and Refractive Surgery

Purpose: To determine the trends in anesthesia techniques for cataract surgery over the past decade and their relationship to surgical complications. Setting: Clinics affiliated with the European Registry of Quality Outcomes for Cataract and Refractive Surgery (EUREQUO). Design: Retrospective cross-sectional register-based study. Methods: Variables include patient demographics, visual acuity, ocular comorbidities, surgery characteristics, intraoperative complications, and postoperative complications for the study period from January 2008, to December 2018. The anesthesia methods registered in the EUREQUO and included in the study are topical, combined topical and intracameral, sub-Tenon, regional, and general anesthesia. Multivariate logistic regression models for each complication were constructed to estimate the adjusted odds ratio (OR) and 95% CIs. Results: Complete data were available of 1 354 036 cataract surgeries. Topical anesthesia increased significantly over time (from 30% to 76%, P < .001). Sub-Tenon and regional anesthesia decreased (from 27% and 38% to 16% and 6%, respectively, P < .001), and general and combined topical and intracameral anesthesia remained stable (around 2%). Sub-Tenon (OR, 0.80; 95% CI, 0.71-0.91, P < .001), regional (0.74; 95% CI, 0.71-0.78, P < .001), general (0.53; 95% CI, 0.50-0.56, P < .001), and intracameral anesthesia (0.76; 95% CI, 0.64-0.90, P = .001) carried a significantly decreased risk of posterior capsule rupture (PCR), with and without dropped nucleus, compared with topical anesthesia. The risk of endophthalmitis was significantly lower with regional anesthesia compared with topical anesthesia (OR, 0.60; 95% CI, 0.44-0.82, P = .001). Conclusions: The use of topical anesthesia for cataract surgery increased over time. Topical anesthesia is associated with an increased risk of PCR with and without dropped nucleus, and endophthalmitis

Development of machine learning models to predict posterior capsule rupture based on the EUREQUO registry

Purpose: To evaluate the performance of different probabilistic classifiers to predict posterior capsule rupture (PCR) prior to cataract surgery. Methods: Three probabilistic classifiers were constructed to estimate the probability of PCR: a Bayesian network (BN), logistic regression (LR) model, and multi‐layer perceptron (MLP) network. The classifiers were trained on a sample of 2 853 376 surgeries reported to the European Registry of Quality Outcomes for Cataract and Refractive Surgery (EUREQUO) between 2008 and 2018. The performance of the classifiers was evaluated based on the area under the precision‐recall curve (AUPRC) and compared to existing scoring models in the literature. Furthermore, direct risk factors for PCR were identified by analysing the independence structure of the BN. Results: The MLP network predicted PCR overall the best (AUPRC 13.1 ± 0.41%), followed by the BN (AUPRC 8.05 ± 0.39%) and the LR model (AUPRC 7.31 ± 0.15%). Direct risk factors for PCR include preoperative best‐corrected visual acuity (BCVA), year of surgery, operation type, anaesthesia, target refraction, other ocular comorbidities, white cataract, and corneal opacities. Conclusions: Our results suggest that the MLP network performs better than existing scoring models in the literature, despite a relatively low precision at high recall. Consequently, implementing the MLP network in clinical practice can potentially decrease the PCR rate

The changes of shape of the human cornea with age

Póster presentado al 6th EOS Topical Meeting on Visual and Physiological Optics celebrado en Dublin (Irlanda) del 20 al 22 de agosto de 2012.The shape of the aging cornea was studied in a group of 407 nor-mal eyes. The most significant changes found were: a small increase of the curvature, eccentricity and irregularity of the anterior surface with age. For both the anterior and posterior surfaces the misalign-ment with the keratometric axis increased with age. [Introduction]: There are several studies on the mean corneal shape based on fit-ting the surface topography to a given model. The most popular models divide the surface elevation S into a regular basis surface, B (with a straightforward optical interpretation, such as spheres, coni-coids, 3 axes ellipsoids or biconics) plus a residual R = S – B which accounts for local irregularities and departures from the basis sur-face B. It is also common to fit the residual to a Zernike polynomial expansion. In an earlier study the geometry and optical proper-ties of the mean cornea were analyzed using a general 3-axis ellip-soid, so that we could determine the position (x0, y0, z0) and orienta-tion (α, β, γ) of the optical axis in the 3D space. The strength of that B model was patent as it provided significant lower fitting errors than standard (canonical) models. Here we apply a similar approach to a larger set (407 corneas), covering a wide range of ages (4 - 79 years). The measurements were taken with a Scheimpflug system (PentacamTM) which provides topographies of both front and back surfaces. The B model was also improved and generalized to a general biconic defined by 10 parameters: apex radii (RMax, Rmin), conic constants (QMax, Qmin) plus position and orientation in space. The residual R was analyzed by a 8th order Zernike polynomial expansion.[Discussion]: The RMS residual (fit error) shows marked differences between the anterior ( = 5.7 μm) and posterior ( = 14.6 μm) surfaces (Sant and Spos). This suggests that the biconic is a good model but only for the anterior surface. Interestingly, this residual slightly increases with age for Sant but shows the opposite trend for Spos. Fig. 1 shows the evolution of the horizontal (β) and vertical (α) angles between the biconic and keratometric axes. The linear regression shows a clear trend to increase both angles (misalignment) with age. Even though the predictability is poor due to a high intersubject variability, such trend has a high statistical significance (p-values 0.0236 and 0.0033 for βant, and βpos; and even lower p-values for α). In addition there is a clear misalignment between Sant and Spos of ~2.5º for both angles. Similar plots were obtained for radii, conic constants and apex coordinates for both surfaces. The radii of the anterior surface were found to decrease slightly but significantly (P ant = 7.85 - 0.0047·age mm; ant = 7.70 - 0.0040·age), as well as the conic constant along the meridian of maximum curvature for both surfaces (ant = -0.30-0.0025·age; pos = - 0.55 -0.0024·age). Several parameters, on the other hand, remained constant with age, such as the apical radii of the back surface (pos = 6.27 ± 0.26 mm; pos = 5.92 ± 0.30 mm); the conic constant along the axis of minimum cur-vature for both anterior and posterior surfaces (ant = -0.38 ± 0.13; pos = -0.49 ± 0.14 mm) do not change significantly with age; and Euler angle γ, corresponding with the astigmatism axis, which on average is close to vertical, but shows a large inter-subject variability. The statistical analysis presented so far is somewhat preliminary in the sense that it is based on the complete set without removing out-liers. Nevertheless, it is worth noting that this will probably affect the exact values of parameters, but the main trends and conclusions are expected to be basically the same.[Conclusions]: These results confirm previous findings, such as the increase of the corneal power, or the tendency of the cornea to become more prolate with age. In addition, the biconic model permits to iden-tify that the conic constant has a maximum change along the merid-ian of maximum curvature (no change in the orthogonal one). A new finding (to our knowledge) is that our results suggest a significant progressive tip/tilt of the optical axis of the (best fit) biconic with age, for both anterior and posterior corneal surfaces.Supported by the Spanish MEC, grant FIS2011-22496 to Rafael Navarro and by the Flemish IWT, grant 110684 to Jos Rozema.Peer reviewe

SyntEyes: A higher-order statistical eye model for healthy eyes

[Purpose]: Stochastic eye models are a method to generate random biometry data with the variability found in the general population for use in optical calculations. This work improves the accuracy of a previous model by including the higher-order shape parameters of the cornea. [Methods]: The right eye biometry of 312 subjects (40.8 ± 11.0 years of age) were measured with an autorefractometer, a Scheimpflug camera, an optical biometer, and a ray tracing aberrometer. The corneal shape parameters, exported as Zernike coefficients, were converted to eigenvectors for dimensional reduction. The remaining 18 parameters were modeled as a sum of two multivariate Gaussians, from which an unlimited number of synthetic data sets (SyntEyes) were generated. After conversion back to Zernike coefficients, the data were introduced into ray tracing software. [Results]: The mean values of nearly all SyntEyes parameters were statistically equal to those of the original data (two one-sided t-test, P > 0.05/109, Bonferroni correction). The variability of the SyntEyes parameters was similar to the original data for most important shape parameters and intraocular distances (F-test, P 0.05/109). The same was seen for the correlations between higher-order shape parameters. After applying simulated cataract or refractive surgery to the SyntEyes model, a very close resemblance to previously published clinical outcome data was seen. [Conclusions]: The SyntEyes model produces synthetic biometry that closely resembles clinically measured data, including the normal biological variations in the general population.Supported by research grants from the Flemish government agency for Innovation by Science and Technology (Grant IWT/110684) and the Spanish Ministry of Economy and Competitiveness (FIS2014-58303-P).Peer Reviewe

Exchange of multifocal IOL decentered in a fibrose capsular bag in the lens-IOL

A case of an IOL exchange. It is a multifocal slightly tilted IOL. The patient was operated six years ago. When she was in the mean time operated on the other eye with a bag-in-the-lens toric correction, she saw the difference and wanted to have an exchange of this decentered lens. The quality of vision was otherwise not good enough for her dominant eye

The bigaussian nature of ocular biometry

To study how the leptokurtic shape of the refractive distribution can be derived from ocular biometry by means of a multivariate Gaussian model

Comparing Methods to Estimate the Human Lens Power

PURPOSE. To compare the accuracy of different methods of calculating human lens power when lens thickness is not available. METHODS. Lens power was calculated by four methods. Three methods were used with previously published biometry and refraction data of 184 emmetropic and myopic eyes of 184 subjects (age range, 18-63 years; spherical equivalent range, Ϫ12.38 to ϩ0.75 D). These three methods consist of the Bennett method, which uses lens thickness, a modification of the Stenström method and the BennettRabbetts method, both of which do not require knowledge of lens thickness. These methods include c constants, which represent distances from lens surfaces to principal planes. Lens powers calculated with these methods were compared with those calculated using phakometry data available for a subgroup of 66 emmetropic eyes (66 subjects). RESULTS. Lens powers obtained from the Bennett method corresponded well with those obtained by phakometry for emmetropic eyes, although individual differences up to 3.5 D occurred. Lens powers obtained from the modified-Stenström and BennettRabbetts methods deviated significantly from those obtained with either the Bennett method or phakometry. Customizing the c constants improved this agreement, but applying these constants to the entire group gave mean lens power differences of O cular refraction is determined by axial length, anterior chamber depth, corneal power ,and lens power. Although axial length and keratometry measurements have become routine clinically, determining lens power is problematic, as the lens radii of curvature and refractive index distribution are usually not available. Although techniques have been proposed in the literature to estimate the radii in vivo, 1-5 they are currently too complicated to be used in large-scale studies or clinical practice. Because of this impracticality, various methods have been proposed that use ocular biometry, such as keratometry, ocular axial length, anterior chamber depth, lens thickness, and ocular refraction, to estimate the power of an equivalent lens at a location near that of the lens. Since these biometric parameters are easily determined, such methods can provide a quick estimate of the equivalent lens power. The most well known of these methods was proposed by Bennett, 6 who used a thick-lens description that makes assumptions about the shape and refractive index distribution of the lens based on the Gullstrand-Emsley schematic eye. 7 From this, he could calculate the equivalent lens power in a way that has been shown to be accurate in comparison with phakometry. Other methods do not require this knowledge of the lens thickness, such as the approaches proposed by Stenström 11 These approaches might be useful in a clinical practice using biometry devices that do not provide lens thickness (e.g., IOL Master; Carl Zeiss Meditec, Dublin, CA), or in analysis of historical biometry data. The purposes of this study are (1) to verify the agreement that Dunne et al. 8 found between the Bennett method and phakometry; to (2) compare lens powers obtained with the Bennett method, our modification of the Stenström method, and the Bennett-Rabbetts method for previously published data of emmetropic and myopic eyes, and (3) to provide customized constants to optimize the performance of these three methods. The results allow improvement of our statistical eye model 12 by including a more reliable method to estimate lens power when lens thickness is not available. METHODS Subjects To estimate the accuracy of the lens power calculations with respect to phakometry, we need the biometry and phakometry data of a population of normal subjects. For this purpose, we used previously published data by Atchison et al. To compare the results of the three power calculation methods for a wider range of refractions, the first dataset was supplemented by a second set from the same research group. 14 This dataset contained 118 eyes of 118 emmetropic and myopic subjects (43 men, 75 women; 74 Caucasian, 44 non-Caucasian) with a mean spherical equivalent refraction of Ϫ2.69 Ϯ 2.79 D (range, Ϫ12.3 to ϩ0.75 D) and an average subject age of 25.4 Ϯ 5.1 years (range, 18 -36 years). No phakometry data were available for this second dataset. Inclusion criteria were stringent, to ensure that only healthy eyes were included. These entailed, among others, corrected visual acuity better than 6/6 on an ETDRS chart, an intraocular pressure below 21 mm Hg, and a Pelli-Robson contrast sensitivity of 1.65 or better for subjects of 40 years of age and younger and a contrast sensitivity of 1.50 or better for subjects older than 40 years of age. In the myopic dataset, eyes with astigmatism larger than 0.5 D were also excluded. The subjects&apos; eyes were not dilated or cyclopleged before testing, which might have caused some degree of accommodation in some of From th