Vitrectomy and internal limiting membrane peeling for macular folds secondary to hypotony in myopes

Hypotony maculopathy (HM) changes may persist, and visual acuity remains poor, despite normalization of intraocular pressure (IOP). The aim of this study was to evaluate the visual and anatomical results of pars plana vitrectomy (PPV), internal limiting membrane (ILM) peeling, and 20% SF6 gas tamponade in five myopic patients with HM. This retrospective interventional study was conducted at the Barraquer Center of Ophthalmology, a tertiary care center in Barcelona, Spain, and included five eyes from five consecutive patients (aged 55.4±13.1 years) with HM caused by different conditions. All the patients were treated with 23-gauge PPV, ILM peeling, and 20% SF6 gas tamponade. Preoperative and postoperative evaluation was performed using anterior and posterior biomicroscopy and best corrected visual acuity (BCVA) by logMAR charts. Before surgery, median spherical equivalent was −13.1 (range −7, −19) diopters of myopia. Preoperatively, four cases presented IOP 6.5 mmHg was achieved over 16 (range 16-28) weeks, without resolution of HM; increased IOP was not achieved in the remaining case treated 2 weeks after diagnosis of HM. One case presented IOP >6.5 mmHg with HM for 28 weeks before surgery. Preoperative BCVA was 0.7 (range 0.26-2.3) logMAR, and 0.6 (range 0.3-0.7) logMAR and 0.5 (range 0.2-1) logMAR, respectively, at 4 and 12 months after surgery. There was no statistically significant difference between preoperative and postoperative BCVA. Hyper-pigmentation lines in the macular area were observed in three cases with hypotony. These lines progressed after surgery despite resolution of the retinal folds in the three cases, and BCVA decreased in parallel in two of these cases. PPV with ILM peeling followed by gas tamponade is a good alternative for the treatment of HM in myopic patients. However, persistent choroidal folds may compromise BCVA. We therefore recommend initiating treatment as early as possible

Localized Refractive Changes Induced by Symmetric and Progressive Asymmetric Intracorneal Ring Segments Assessed with a 3D Finite-Element Model.

To build a representative 3D finite element model (FEM) for intracorneal ring segment (ICRS) implantation and to investigate localized optical changes induced by different ICRS geometries, a hyperelastic shell FEM was developed to compare the effect of symmetric and progressive asymmetric ICRS designs in a generic healthy and asymmetric keratoconic (KC) cornea. The resulting deformed geometry was assessed in terms of average curvature via a biconic fit, sagittal curvature (K), and optical aberrations via Zernike polynomials. The sagittal curvature map showed a locally restricted flattening interior to the ring (Kmax -11 to -25 dpt) and, in the KC cornea, an additional local steepening on the opposite half of the cornea (Kmax up to +1.9 dpt). Considering the optical aberrations present in the model of the KC cornea, the progressive ICRS corrected vertical coma (-3.42 vs. -3.13 µm); horizontal coma (-0.67 vs. 0.36 µm); and defocus (2.90 vs. 2.75 µm), oblique trefoil (-0.54 vs. -0.08 µm), and oblique secondary astigmatism (0.48 vs. -0.09 µm) aberrations stronger than the symmetric ICRS. Customized ICRS designs inspired by the underlying KC phenotype have the potential to achieve more tailored refractive corrections, particularly in asymmetric keratoconus patterns

Human Lens Capsule Thickness as a Function of Age and Location along the Sagittal Lens Perimeter

PURPOSE. To investigate the variation in the thickness of the human lens capsule along the lens perimeter, as well as its changes with age. METHODS. Altogether, 26 human donor lenses, aged 12 to 103 years, were histologically processed. Sagittal sections were stained for collagen with periodic acid-Schiff (PAS). Serial images of the lens border were taken with a photomicroscope and 25ϫ objective. Capsular thickness was measured every 250 m along the entire lens perimeter. RESULTS. All studied capsules were thicker anteriorly, continuously increasing with age from 11 to 15 m in average at the anterior lens pole. Maximum thickness was located at the anterior midperiphery, increasing with age from 13.5 to 16 m. In most cases, there was a local thinning at a pre-equatorial zone, recovering to approximately 7 m at the equator. The latter value, as well as the minimal thickness at the posterior pole (mean 3.5 m), did not change with age, whereas the average thickness at the posterior periphery decreased from 9 to 4 m. CONCLUSIONS. The human lens capsule thickness is at its maximum at the anterior midperiphery, which appears to be located central to the zonular insertion. It increases with age, especially at the anterior pole, while the midperipheral zone stabilizes or slightly decreases after the seventh decade. The anterior zonular insertion is actually related to a local preequatorial thinning, which remains unchanged with age. There was no posterior peripheral thickening, except in a few younger patients, with a modest relative maximum roughly at the equator. From here, the posterior capsule becomes progressively thinner and also diminishes with age, except for the thinnest, but stable posterior pole. (Invest Ophthalmol Vis Sci

Outcome analysis of intracorneal ring segments for the treatment of keratoconus based on visual, refractive, and aberrometric impairment

PURPOSE: To analyze the outcomes of intracorneal ring segment (ICRS) implantation for the treatment of keratoconus based on preoperative visual impairment. DESIGN: Multicenter, retrospective, nonrandomized study. METHODS: A total of 611 eyes of 361 keratoconic patients were evaluated. Subjects were classified according to their preoperative corrected distance visual acuity (CDVA) into 5 different groups: grade I, CDVA of 0.90 or better; grade II, CDVA equal to or better than 0.60 and worse than 0.90; grade III, CDVA equal to or better than 0.40 and worse than 0.60; grade IV, CDVA equal to or better than 0.20 and worse than 0.40; and grade plus, CDVA worse than 0.20. Success and failure indices were defined based on visual, refractive, corneal topographic, and aberrometric data and evaluated in each group 6 months after ICRS implantation. RESULTS: Significant improvement after the procedure was observed regarding uncorrected distance visual acuity in all grades (P < .05). CDVA significantly decreased in grade I (P < .01) but significantly increased in all other grades (P < .05). A total of 37.9% of patients with preoperative CDVA 0.6 or better gained 1 or more lines of CDVA, whereas 82.8% of patients with preoperative CDVA 0.4 or worse gained 1 or more lines of CDVA (P < .01). Spherical equivalent and keratometry readings showed a significant reduction in all grades (P ≤ .02). Corneal higher-order aberrations did not change after the procedure (P ≥ .05). CONCLUSIONS: Based on preoperative visual impairment, ICRS implantation provides significantly better results in patients with a severe form of the disease. A notable loss of CDVA lines can be expected in patients with a milder form of keratoconus

Soemmerring&rsquo;s Rings Developed around IOLs, in Human Donor Eyes, Can Present Internal Transparent Areas

Soemmerring&rsquo;s rings consist of a ring of lens epithelial derived cells that grow along the periphery of an aphakic lens capsule, or around an intraocular lens. These rings when visualized frontally, appear opaque, however, in some cases the cells that compose these rings are organized in the same fashion as those in normal transparent adult lenses. Thus, our purpose was to test whether any part of the adult Soemmerring&rsquo;s ring could be transparent and how this related to morphological factors. To study this, 16 Soemmerring&rsquo;s rings were extracted from donor eye globes. After imaging, they were thickly sectioned sagittally in order to analyze the degrees of transparency of different areas. All samples were also histologically analyzed using alpha smooth muscle actin, Vimentin, wheat germ agglutinin and DAPI. Our results showed that many samples had some transparent areas, mostly towards the center of their cross-section. Of the factors that we analyzed, only lens fiber organization at the bow region and an increased area of mature lens fiber cells had a significant relation to the degree of transparency at the center. Thus, we can conclude that as Soemmerring&rsquo;s rings mature, they can develop organized and transparent areas of lens cells

Cortical Cataract and Refractive Error

Purpose: To evaluate the relationship between the presence of cortical cataract and accommodation effort, using refractive error as a proxy. Methods: Patients between 50 and 90 years, scheduled for cataract surgery, were selected with the help of a photographic database. Nuclear and cortical cataract were graded and patients grouped having no cataract, pure cortical, mixed or pure nuclear cataract. Refraction data at the time of the photograph was converted to estimated spherical equivalent refractive error each patient would have had at the age of 45 years. Results: From the initial 239 eyes from 239 patients, cases with myopia below –6.5 dpt and hyperopia above 6.5 dpt were excluded, resulting in 199 cases for final analysis. Eyes with no cataract showed the lowest median refractive error (–3.65 dpt), followed by the pure nuclear group (–2.69 dpt). The median refractive error for pure cortical (–0.23 dpt) and mixed cataracts (–0.87 dpt) were close to emmetropia. Cortical cataracts were found in 37% of myopes, 82% of emmetropes, and 85% of hyperopes. Conclusion: Emmetropes and hyperopes tend to develop more cortical cataract than myopes. These cortical cataracts might be caused by shear stress inside the crystalline lens due to accommodation efforts at the time of onset of presbyopia

Cortical Cataract and Refractive Error

Purpose: To evaluate the relationship between the presence of cortical cataract and accommodation effort, using refractive error as a proxy. Methods: Patients between 50 and 90 years, scheduled for cataract surgery, were selected with the help of a photographic database. Nuclear and cortical cataract were graded and patients grouped having no cataract, pure cortical, mixed or pure nuclear cataract. Refraction data at the time of the photograph was converted to estimated spherical equivalent refractive error each patient would have had at the age of 45 years. Results: From the initial 239 eyes from 239 patients, cases with myopia below –6.5 dpt and hyperopia above 6.5 dpt were excluded, resulting in 199 cases for final analysis. Eyes with no cataract showed the lowest median refractive error (–3.65 dpt), followed by the pure nuclear group (–2.69 dpt). The median refractive error for pure cortical (–0.23 dpt) and mixed cataracts (–0.87 dpt) were close to emmetropia. Cortical cataracts were found in 37% of myopes, 82% of emmetropes, and 85% of hyperopes. Conclusion: Emmetropes and hyperopes tend to develop more cortical cataract than myopes. These cortical cataracts might be caused by shear stress inside the crystalline lens due to accommodation efforts at the time of onset of presbyopia

Refractive changes of a new asymmetric intracorneal ring segment with variable thickness and base width: A 2D finite-element model

Purpose To evaluate the local geometric effects of a unilateral intrastromal ring segment with a combined variation of ring thickness and base width in a finite element simulation, and to compare it against the isolated effect of thickness or base width variation alone. Methods A two-dimensional finite-element model of a transversely isotropic cornea was created assuming either axisymmetric stress or plane strain condition. The model geometry was composed of a three-layered corneal tissue (epithelium, anterior and posterior stroma) fixed at the limbus. The implantation of a triangular-shape asymmetric ring segment with varying ring thickness (150 to 300 μm) and base width (600 to 800 μm) was simulated. Also, changes induced by thickness or base width alone were studied and compared their combined effect in the asymmetric ring segment. Geometrical deformation of the simulated cornea and sagittal curvature were the main parameters of study. Results Increasing ring thickness and base width along the arc of the asymmetric ring segment produced a more pronounced flattening in this part of the ring. The asymmetric design did find a good balance between maximizing corneal flattening at one end and minimizing it at the other end, compared to the isolated effect of ring thickness and width. Ring thickness was the most robust parameter in flattening both, the central and peripheral cornea. Conclusion The finite-element model permitted a theoretical study of corneal deformation undergoing implantation of realistic and hypothetical ring geometries. Intracorneal asymmetric ring segments with varying thickness and base width can be a good alternative in corneas with asymmetric keratoconus phenotypes.ISSN:1932-620

Morphology of age-related cuneiform cortical cataracts: The case for mechanical stress

AbstractWe evaluated the gross morphology, location, and fiber cell architecture of equatorial cortical opacities in the aging human lens. Using dark-field stereomicroscopy, we photographed donor lenses in toto and as thick slices. In addition, we investigated the details of the fiber cell architecture using fluorescent staining for membranes and by scanning electron microscopy. We then combined our data with data from recent studies on lens viscoelasticity. We found that small cortical and cuneiform opacities are accompanied by changes in fiber structure and architecture mainly in the equatorial border zone between the lens nucleus and cortex. Because the lens cortex and nucleus have different viscoelastic properties in young and old lenses, we hypothesize that external forces during accommodation cause shear stress predominantly in this border zone. The location of the described changes suggests that these mechanical forces may cause fiber disorganization, small cortical opacities, and ultimately, cuneiform cataracts