Morphogeometric analysis for characterization of keratoconus considering the spatial localization and projection of apex and minimum corneal thickness point

This work evaluates changes in new morphogeometric indices developed considering the position of anterior and posterior corneal apex and minimum corneal thickness (MCT) point in keratoconus. This prospective comparative study included 440 eyes of 440 patients (age, 7–99 years): control (124 eyes) and keratoconus (KC) groups (316 eyes). Tomographic information (Sirius®, Costruzione Strumenti Oftalmici, Italy) was treated with SolidWorks v2013, creating the following morphogeometric parameters: geometric axis–apex line angle (GA–AP), geometric axis–MCT line angle (GA–MCT, apex line–MCT line angle (AP–MCT), and distances between apex and MCT points on the anterior (anterior AP–MCTd) and posterior corneal surface (posterior AP–MCTd). Statistically significant higher values of GA–AP, GA–MCT, AP–MCT and anterior AP–MCTd were found in the keratoconus group (p ≤ 0.001). Moderate significant correlations of corneal aberrations (r ≥ 0.587, p < 0.001) and corneal thickness parameters (r ≤ −0.414, p < 0.001) with GA–AP and AP–MCT were found. Anterior asphericity was found to be significantly correlated with anterior and posterior AP–MCTd (r ≥ 0.430, p < 0.001). Likewise, GA–AP and AP–MCT showed a good diagnostic ability for the detection of keratoconus, with optimal cutoff values of 9.61° (sensitivity 85.5%, specificity 80.3%) and 18.08° (sensitivity 80.5%, specificity 78.7%), respectively. These new morphogeometric indices allow a clinical characterization of the 3-D structural alteration occurring in keratoconus, with less coincidence in the spatial projection of the apex and MCT points of both corneal surfaces. Future studies should confirm the potential impact on the precision of these indices of the variability of posterior corneal surface measurements obtained with Scheimpflug imaging technology.This publication has been carried out in the framework of the Thematic Network for Co-Operative Research in Health (RETICS), reference number RD16/0008/0012, financed by the Carlos III Health Institute–General Subdirection of Networks and Cooperative Investigation Centers (R&D&I National Plan 2013–2016) and the European Regional Development Fund (FEDER). The author David P. Piñero has been supported by the Ministry of Economy, Industry and Competitiveness of Spain within the program Ramón y Cajal, RYC-2016-20471

The Value of Anterior Segment Optical Coherence Tomography in Different Types of Corneal Infections: An Update

Anterior segment optical coherence tomography (AS-OCT) is a modality that uses low-coherence interferometry to visualize and assess anterior segment ocular features, offering several advantages of being a sterile and noncontact modality that generates high-resolution cross-sectional images of the tissues. The qualitative and quantitative information provided by AS-OCT may be extremely useful for the clinician in the assessment of a wide spectrum of corneal infections, guiding in the management and follow-up of these patients. In clinical practice, infections are routinely evaluated with slit-lamp biomicroscopy, an examination and imaging modality that is limited by the physical characteristics of light. As a consequence, the depth of pathology and the eventually associated corneal edema cannot be accurately measured with the slit-lamp. Therefore, it represents a limit for the clinician, as in vivo information about corneal diseases and the response to treatment is limited. Resolution of corneal infection is characterized by an early reduction in corneal edema, followed by a later reduction in infiltration: both parameters can be routinely measured with standardized serial images by AS-OCT

Retinal Optical Quality of Multifocal Refractive and Monofocal Intraocular Lenses

(1) Background: This study aimed to evaluate and compare the clinical optical image quality following implantation with different premium IOLs by the analysis of the point spread function (PSF) Strehl ratio using a Pyramidal WaveFront-based sensor (PWS) aberrometer at two different pupil sizes. (2) Methods: This study included 96 eyes of 70 patients implanted with: (1) 19 AcrySof SA60AT (control group); (2) 24 LENTIS Mplus LS-313 MF30; (3) 33 LENTIS Mplus LS-313 MF15; and (4) 20 Precizon Presbyopic. Main outcome measures were PSF Strehl ratio, PSF Strehl ratio excluding second-order aberrations (PSFw2), total root-mean-square (RMS), and low- and high-order aberrations&rsquo; RMS measured by PWS aberrometer. Results: SA60AT had the highest significant PSFw2 Strehl ratio at both 3- and 4-mm pupil size (0.41 &plusmn; 0.11 and 0.28 &plusmn; 0.07) followed by LENTIS Mplus 15 (group C, 0.35 &plusmn; 0.1 and 0.21 &plusmn; 0.06) and a near tie between LENTIS MPLUS 30 (group B, 0.27 &plusmn; 0.08 and 0.18 &plusmn; 0.06) and Precizon Presbyopic (group D, 0.27 &plusmn; 0.07 and 0.17 &plusmn; 0.04). MPlus MF15 was found to be significantly better than MPlus MF30 at both 3.00 mm (p &lt; 0.0001) and 4.00 mm (p = 0.002). (4) Conclusions: The PSFw2 represents a new tool to objectively evaluate the far distance retinal image quality of multifocal IOLs, and the far distance clinical image quality parameters measured by PWS aberrometer differed significantly according to the technology of the implanted lens

Retinal Optical Quality of Multifocal Refractive and Monofocal Intraocular Lenses

(1) Background: This study aimed to evaluate and compare the clinical optical image quality following implantation with different premium IOLs by the analysis of the point spread function (PSF) Strehl ratio using a Pyramidal WaveFront-based sensor (PWS) aberrometer at two different pupil sizes. (2) Methods: This study included 96 eyes of 70 patients implanted with: (1) 19 AcrySof SA60AT (control group); (2) 24 LENTIS Mplus LS-313 MF30; (3) 33 LENTIS Mplus LS-313 MF15; and (4) 20 Precizon Presbyopic. Main outcome measures were PSF Strehl ratio, PSF Strehl ratio excluding second-order aberrations (PSFw2), total root-mean-square (RMS), and low- and high-order aberrations’ RMS measured by PWS aberrometer. Results: SA60AT had the highest significant PSFw2 Strehl ratio at both 3- and 4-mm pupil size (0.41 ± 0.11 and 0.28 ± 0.07) followed by LENTIS Mplus 15 (group C, 0.35 ± 0.1 and 0.21 ± 0.06) and a near tie between LENTIS MPLUS 30 (group B, 0.27 ± 0.08 and 0.18 ± 0.06) and Precizon Presbyopic (group D, 0.27 ± 0.07 and 0.17 ± 0.04). MPlus MF15 was found to be significantly better than MPlus MF30 at both 3.00 mm (p p = 0.002). (4) Conclusions: The PSFw2 represents a new tool to objectively evaluate the far distance retinal image quality of multifocal IOLs, and the far distance clinical image quality parameters measured by PWS aberrometer differed significantly according to the technology of the implanted lens

A three-dimensional morpho-volumetric similarity study of Down syndrome keratopathy vs. keratoconus

Background: To compare and contrast morpho-volumetric features between Down syndrome (DS) cornea and non-DS keratoconic cornea by three-dimensional (3D) modelling. Methods: Forty-three subjects (43 eyes) with DS and 99 patients matching their age and sex (99 eyes) with keratoconus (KC) were included in this single-center cross-sectional study. Main outcome measures were high-order aberrations (HOA), central corneal thickness (CCT), spherical equivalent refraction, and morpho-volumetric parameters established using a 3D corneal model, such as deviation of anterior and posterior corneal apices (D-apexant/D-apexpost) and minimum thickness points (D-mctant/D-mctpost) from corneal vertex, areas of the anterior and posterior surfaces (A(ant)/A(post)), sagittal area passing through the anterior and posterior corneal apices (A(apexant)/A(apexpost)) and minimum thickness point (A(mctpost)) and corneal volume of the complete cornea (V-total). Results: Age, gender, spherical equivalent refraction, CCT and V-total were similar between the net on-DS KC and DS groups (P > 0.05), while non-DS KC group had higher HOA than the DS group (P 0.05). D-apexant, A(ant), A(post) and A(apexant) showed higher values in the DS group than in the non-DS KC group, whereas D-apexpost showed a reduction in the DS group when compared with the non-DS KC group (P 0.05). Conclusions: This study demonstrated that anterior and posterior corneal apex dynamics were specifically different in DS subjects, as the anterior apex tends to displace more prominently when compared to that from the non-DS KC group, while the posterior apex appears to be more stable than that in non-DS KC, which also support the theory that DS patients suffer from a specific keratopathy, distinctively different to KC but strongly related to it, and probably showing a diversity of corneal phenotypes in all cases of DS.Thematic Network for Co-Operative Research in Health-Red Tematica De Investigacion Oftalmologica, RETICS; Carlos III Health Institute-General Sub-direction of Networks and Cooperative Investigation Centres [RD16/0008/0012]; European Regional Development Fund (FEDER); Instituto de Salud Carlos III (ISCIII); European UnionThis study was supported in part by the Thematic Network for Co-Operative Research in Health (Red Tematica De Investigacion Oftalmologica, RETICS) (Reference No. RD16/0008/0012) and financed by the Carlos III Health Institute-General Sub-direction of Networks and Cooperative Investigation Centres (R ; D ; I National Plan 2013-2016) and the European Regional Development Fund (FEDER).This publication was carried out within the framework of the project Desarrollo y validacion de un nuevo concepto de caracterizacion biomecanica-morfofuncional de la cornea (Reference No. DTS21/00103).This project was funded by Instituto de Salud Carlos III (ISCIII) and cofunded by the European Union.This study was also carried out in collaboration with the Association for the Integration of the Disabled in the Comarca del Mar Menor (AIDEMAR, collaboration protocol UPCT-AIDEMAR)

Evidence of a Down Syndrome Keratopathy: A Three-Dimensional (3-D) Morphogeometric and Volumetric Analysis

The aim of this study was to investigate whether a different and abnormal corneal profile is present in Down syndrome (DS) by personalized three-dimensional (3D) modelling. This single-centre cross-sectional study included 43 patients with DS (43 eyes) and 58 age-sex-matched control subjects (58 eyes) with normal karyotype and topography. Refraction, central corneal thickness (CCT), aberrations (high-order, coma and spherical), asphericity and morphogeometric/volumetric parameters based on a 3D corneal model that was generated from raw topographical data were evaluated. Deviation of anterior/posterior apex (Dapexant/Dapexpost) and thinnest point (Dmctant/Dmctpost) from corneal vertex, anterior/posterior surface area (Aant/Apost), sagittal area passing through the anterior/posterior apex (Aapexant/Aapexpost) and thinnest point (Amctpost), total corneal volume (Vtotal) and volumetric progression for each 0.05 mm step of the radius value centred to the thinnest point (VOLMCT) and anterior/posterior apex (VOLAAP/VOLPAP) comprised the morphogeometric/volumetric parameters. In the DS group, 58.1% of the eyes presented abnormal topography. High-order and coma aberrations, asphericity, Dapexant, Aant, Apost and Aapexant were significantly higher, whereas CCT, Aapexpost, Amctpost, Vtotal, VOLAAP, VOLPAP and VOLMCT were lower in the DS group than in the control group (p apexpost did not differ between the groups (p > 0.05). This study demonstrates that corneas of the subjects with DS are different and more aberrated than those of normal age- and sex-matched non-DS controls. Anterior corneal apex appears to be displaced in DS even with normal topography, while posterior apex seems stable although topography is abnormal. These findings may help to modify our approach in the diagnosis of keratopathy in subjects with DS

Refractive surgical correction and treatment of keratoconus

Keratoconus is an ectatic corneal disorder that causes severe vision loss. Surgical options allow us to correct, partially or totally, the induced refractive error. Intracorneal ring segments (ICRS) implantation represents a minimally invasive surgical option that improves visual acuity, with a high success rate and a low overall complication rate. Corneal allogenic ICRS consists of ring segments derived from allogenic eye bank -processed donor corneas. Selective topography -guided transepithelial photorefractive or phototherapeutic keratectomy combined with CXL is another way in selected cases to improve spectacles corrected distance visual acuity. The microphotoablative remodeling of the central corneal profile is generally planned by optimizing the optical zones and minimizing tissue consumption. Phakic intraocular lens (PIOL) implant is considered in patients with stable disease and acceptable anatomical requirements. The two types of pIOLs, depending on their implantation inside the eye, are anterior chamber-pIOLs, which fixate to the anterior surface of the iris by using a polymethomethacrolate claw at the two haptics, and posterior chamber-pIOLs. In patients with both cataracts and keratoconus, the correct IOL power is difficult to obtain due to the irregular corneal shape and K values. Toric IOL is recommended, but carefully judging the topography and the possible need of subsequent keratoplasties

Simultaneous tectonic Descemet stripping endothelial keratoplasty and tectonic Bowman layer transplant for the management of corneal perforation

AIM: To report the outcomes of three cases of corneal perforation managed with simultaneous tectonic Descemet stripping endothelial keratoplasty (t-DSEK) and tectonic Bowman layer transplant (t-BLT) as an alternative to tectonic penetrating keratoplasty (t-PKP). METHODS: Three eyes of three patients receiving simultaneous t-DSEK and t-BLT for corneal perforation were included. The technique for DSEK was modified depending on individual requirements. The t-BLT technique was standardised using an 8 mm graft and fixated with a running suture. Success was measured by the ability of this procedure to close a corneal perforation. RESULTS: All three cases achieved tectonic eye globe restoration and remained stable during the minimum 3-month observation period. Reinterventions were relatively common: 2 cases required amniotic membrane transplant for persistent epithelial defects. One case required DSEK rebubbling. One case developed angle closure glaucoma requiring surgical peripheral iridectomy. CONCLUSION: Simultaneous t-DSEK and t-BLT may be a useful strategy for the management of corneal perforation as an alternative management to t-PKP for selected cases

Novel Multivariable Evolutionary Algorithm-Based Method for Modal Reconstruction of the Corneal Surface from Sparse and Incomplete Point Clouds

Three-dimensional reconstruction of the corneal surface provides a powerful tool for managing corneal diseases. This study proposes a novel method for reconstructing the corneal surface from elevation point clouds, using modal schemes capable of reproducing corneal shapes using surface polynomial functions. The multivariable polynomial fitting was performed using a non-dominated sorting multivariable genetic algorithm (NS-MVGA). Standard reconstruction methods using least-squares discrete fitting (LSQ) and sequential quadratic programming (SQP) were compared with the evolutionary algorithm-based approach. The study included 270 corneal surfaces of 135 eyes of 102 patients (ages 11–63) sorted in two groups: control (66 eyes of 33 patients) and keratoconus (KC) (69 eyes of 69 patients). Tomographic information (Sirius, Costruzione Strumenti Oftalmici, Italy) was processed using Matlab. The goodness of fit for each method was evaluated using mean squared error (MSE), measured at the same nodes where the elevation data were collected. Polynomial fitting based on NS-MVGA improves MSE values by 86% compared to LSQ-based methods in healthy patients. Moreover, this new method improves aberrated surface reconstruction by an average value of 56% if compared with LSQ-based methods in keratoconus patients. Finally, significant improvements were also found in morpho-geometric parameters, such as asphericity and corneal curvature radii

Managing dissatisfaction after multifocal intraocular lens implantation through lens exchange using monofocal or alternative multifocal IOLs

Purpose: To manage patient dissatisfaction following multifocal intraocular lens (MF‐IOL) implantation by IOL exchange with either a monofocal or an alternative MF‐IOL, and to compare outcomes in these two groups. Methods: MF‐IOL exchange was performed in 32 patients (64 eyes) with neuroadaptation failure. The MF‐to‐MF group involved patients who had a MF‐IOL exchanged with another MF‐IOL of a different optical profile and the MF‐to‐MO group involved patients who had a MF‐IOL exchanged to a monofocal IOL. Visual outcomes and complications were analysed. The Quality of Vision (QoV) questionnaire, Visual Function Index (VF‐14) and its Rasch‐revised version (VF‐8R) were also used to assess outcomes. Results: There were no significant differences (p > 0.05) in the QoV scores between the two groups, both preoperatively and postoperatively. Preoperatively, there were no significant differences in VF‐14 scores between both groups (p > 0.05). Postoperatively, there were statistically significant differences in VF‐14 (total score, intermediate vision and near vision) in favour of the MF‐to‐MF group (p < 0.05). The postoperative VF‐8R score in the MF‐to‐MF group was significantly better than the MF‐to‐MO group (p ≤ 0.001). Uncorrected and corrected near as well as corrected distance visual acuities were significantly better (p < 0.05) in the MF‐to‐MF group compared to the MF‐to‐MO group at 3 months. Conclusion: Patient dissatisfaction and neuroadaptation failure following MF‐IOL implantation can be managed by an IOL exchange with an alternative optical design of MF‐IOL or a monofocal IOL. Although, in the current study, the MF‐to‐MF group showed some better postoperative results, both options are feasible solutions