Zonula Research Articles

A novel concept of accommodation:Human eyes optical system based on hyperfocal distance-micro zoom

Based on a concept of the hyperfocal distance from photographic lens,this study proposes that emmetropia presents far-hyperfocal distance,near-hyperfocal distance and accommodative hyperfocal distance.When emmetropic presbyopias completely lose the ability of accommodation,its farthest blur point is not beyond 1.5 m,even not being at infinity,and the phenomenon of dark focus both completely match with the definition of hyperfocal distance.On the other hand,after cycloplegic mydriatics in emmetropia,it could be found in the region of depth-of-field that there is no change in the back depth of field (clearness in far vision),but change was found in the front depth of field (blur in near vision).It conforms well to the definition of the hyperfocal distance,demonstrating that human eyes belong to the hyperfocal distance optical system.Furthermore,it is reported that the emmetropic presbyopias rarely matched the spectacles higher than +2.50 D in their whole life;therefore,it can be inferred that their accommodative amplitude in youth is equal to this corrected value.This value accounts for about 4％ of the total refractive power in human eyes,so it is suggested that human eye is a micro zoom optical system.Based on the objective existence of hyperfocal distance,the author proposes that human eye is an integrated accommodative mechanism.It includes three components:the accommodative mechanism of near vision,the measuring and controlling mechanism of near vision,and the general control of near vision.This paper discusses the accommodative mechanism of near vision and the resting mechanism of distance vision based on the hyperfocal distance,and considers that when human eye transfer into the accommodation of near vision from the normal distance vision of hyperfocal distance.There are three different pushing forces contributing to lens deformation and its anterior shift,and these forces cause four different accommodative efforts,which constitute the real accommodative efforts in the relative tissue.This paper also points out that it is only the mode of pushing accommodation that can make the lens vary refraction quickly and greatly,and control the amount of deformation effectively.That can not be achieved by the stretching mode proposed by Tscherning & Schachar,because some authors have verified that excessive pulling would result in decline in the refraction,which would be difficult to regulate and control the eye.Similarly,the self-bulging mode of Helmholtz & Gullstrand will not work neither,because it is unable to control the amount of lens deformation that is its fatal defect. Key words: Accommodation; Hyperfocal; Emmetropia; Lens; Ciliary muscle; Zonule; Iris; Pupil; Depth of focus; Dark focus

Diversity of vascular permeability in iris and ciliary body after penetrating keratoplasty

Background Allograft rejection is a main cause of failure of penetrating keratoplasty,especially in the patient with high risk of rejection condition.Previous study on allograft rejection mechanism focused on limbal and corneal neovascularization,but these factors did not explain all the phenomena of allograft rejection.Research found that immune cells appeared in iris and ciliary body when rejection occurred,but the relationship between these immune cells and allograft rejection is unclear Objective This study was to evaluate the relationship between diversity of vascular permeability in the iris and ciliary body and allograft rejection after penetrating keratoplasty.Methods Seventy clean eight-week-old BALB/c mice were divided into allogeneic corneal transplantation group (60 mice) and blank control group (10 mice).Allogeneic corneal transplantation was performed with the same age of C57BL/6 mice as donor and BALB/c mice as the recipients.The grafts were examined under the slit lamp microscope and scored based on the criteria of Hegde.The mice were sacrificed and iris and ciliary tissue were obtained 5,10 days and rejection after surgery.Immunohistochemistry and reverse transcription PCR (RT-PCR) was used respectively to detect the expression diversities of occludin,zonula occludens protein-1 (ZO-1),matrix metalloproteinase-9(MMP-9),major histocompatibility complex-Ⅱ (MHC-Ⅱ),and CCR5,CCR7 and their mRNA in iris and ciliary body.Image-J image analysis software was used to calculate the quantity of positive cells on iris wholemount,and absorbance of target genes (A values).The use and care of the experimental animals complied the ARVO Resolution on the Use of Animals in Research.Results The mean survival time of corneal gratts was (17±3) days after operation.The mean score was 0.6 in 5 days and 0.5 in 10 days,and 3.3 in 18 days after operation.Expression of ZO-1 reduced significantly,and that of MMP-9 increased obviously at the time of rejection.MHC Ⅱ + cells were scattered in iris and ciliary body in normal mice,and the number of the positive cells (cells/field) was increased after operation with a peak value when rejection occurred.A significant difference was seen between normal mice and rejection mice (1559.67±350.29 vs.4021.83±495.18) (P=0.000).The expressions of occludin mRNA and ZO-1 mRNA in the iris and ciliary body decreased obviously in the rejection mice.Compared with normal mice,theA value of ZO-1 and occluding were 36.74±3.13 vs.110.11±11.88 and 57.54±3.41 vs.59.90±3.50respectively,with significant differences between them (all P＜0.05).The expressions of MMP-9 mRNA,CCR5 mRNA and CCR7 mRNA in the iris and ciliary body increased gradually with the time lapse after operation and peaked when the rejection appeared.The A value of MMP-9 mRNA,CCR5 mRNA and CCR7 mRNA were significantly higher than those of normal mice (20.29±1.19 vs.2.77±0.85 for MMP-9 mRNA; 35.43±2.56 vs.9.11±0.29 for CCR5 mRNA,and 60.83±0.87 vs.0.89 ±0.95 for CCR7 mRNA) respectively (all P＜0.05).Conclusions The permeability of vascules in the iris and ciliary body increase during the allograft rejection after penetrating keratoplasty.Increased antigen presenting cells were also detected. Key words: Penetrating keratoplasty; Allograft rejection; Iris and ciliary body; Vascular permeability

Development, Composition, and Structural Arrangements of the Ciliary Zonule of the Mouse

Here, we examined the development, composition, and structural organization of the ciliary zonule of the mouse. Fibrillin 1, a large glycoprotein enriched in force-bearing tissues, is a prominent constituent of the mouse zonule. In humans, mutations in the gene for fibrillin 1 (FBN1) underlie Marfan syndrome (MS), a disorder characterized by lens dislocation and other ocular symptoms. Fibrillin expression was analyzed by in situ hybridization. The organization of the zonule was visualized using antibodies to Fbn1, Fbn2, and microfibril-associated glycoprotein-1 (Magp1) in conjunction with 5-ethynyl-2'-deoxyuridine (EdU), an S-phase marker. Microfibrils, enriched in Fbn2 and Magp1, were prominent components of the temporary vascular tunic of the embryonic lens. Fbn2 expression by nonpigmented ciliary epithelial cells diminished postnatally and there was a concomitant increase in Fbn1 expression, especially in cells located in valleys between the ciliary folds. Zonular fibers projected from the posterior pars plicata to the lens in anterior, equatorial, and posterior groupings. The attachment point of the posterior zonular fibers consisted of a dense meshwork of radially oriented microfibrils that we termed the fibrillar girdle. The fibrillar girdle was located directly above the transition zone, a region of the lens epithelium in which cells commit to terminal differentiation. The development and arrangement of the murine ciliary zonule are similar to those of humans, and consequently the mouse eye may be a useful model in which to study ocular complications of MS.

Woman With Sudden Loss of Vision—Quiz Case

A 28-YEAR-OLDWOMANOFIRISHDESCENTWITH a history of seizures and high myopia with astigmatism developed sudden loss of visioninherrighteyeandheadachethenight before presentation. She reported no history of trauma. Her cardiac, social, and family histories were unremarkable. Best-corrected visual acuity was 20/300 OD and 20/40 OS, with intraocular pressures of 45 mm Hg on the right and 7 mm Hg on the left. On examination of the right eye, an anterior and inferior subluxation of the lens was noted, with pupillary block and corneal edema obscuring the view of the posterior segment (Figure 1 and Figure 2). Examination of the left eye revealed an inferior lens subluxation with broken zonular fibers superiorly and an unremarkable fundus (Figure 3). Physical examination revealed normal length digits, with no evidence of hyperextensibility, ardiac murmurs, or rash. In addition to pars plana lensectomy/vitrectomy of the right eye, what is the most appropriate approach to diagnosing and treating the patient’s condition?

Le pseudoxanthome élastique et la myopie

Refraction in patients with pseudoxanthoma elasticum (PXE) has not yet been studied in the literature. The purpose of our study was to determine if PXE may be associated with myopia, similarly to Marfan syndrome, another collagen-vascular disease. This cross-sectional study evaluated 53 consecutive patients (32 women and 21 men, mean age 50 ± 16) from September 2009 to June 2011, with 53 age- and sex-matched controls. For each patient, we measured spherical equivalent, visual acuity, keratometry, axial length and crystalline lens power of each eye. Results were compared with Student's t-test. There was a significant difference between the mean values of myopia in the PXE population (-0.98) compared to the group of healthy controls (-0.33, P<0.0093). There was no significant difference between the two groups for the axial length (23.9 mm versus 23.69 mm; P=0.236), keratometry (43.53 versus 43.44; P=0.68), lens power (22.03 versus 21.71; P=0.225). PXE induces calcification of elastic fibers in various human tissues (skin, retina, vascular walls). Since there are no elastic fibers in the cornea or lens, we assume that the elastic zonular fibers may be pathologic in PXE patients. This could result in an anterior displacement of the lens in PXE, which could explain the moderate myopia. PXE may be associated with mild myopia compared to healthy controls. Additional studies, including more patients and evaluating anterior chamber depth and zonular histology are necessary to confirm these preliminary findings.

Matrix Metalloproteinase-2 Degrades Fibrillin-1 and Fibrillin-2 of Oxytalan Fibers in the Human Eye and Periodontal Ligaments &lt;i&gt;In Vitro&lt;/i&gt;

Oxytalan fibers are distributed in the eye and periodontal ligaments (PDL). The ciliary zonule, known as Zinn’s zonule, in the eye is composed of oxytalan fibers, which are bundles of microfibrils consisting mainly of fibrillin-1 and fibrillin-2. As turnover of oxytalan fibers is slow during life, their degradation mechanism remains unclarified. This study was performed to examine degradation pattern of fibrillin-1 and fibrillin-2 by experimental MMP activation. We cultured human non-pigmented ciliary epithelial cells (HNPCEC) and PDL fibroblasts for 7 days, then treated them with concanavalin A to activate matrix metalloproteinase (MMP)-2, and examined the degradation of fibrillin-1 and fibrillin-2 for 72 hr using immunofluorescence. At 7 days of HNPCEC culture, fibrillin-1-positive fibers were observed, some of which merged with fibrillin-2. After MMP-2 activation, fibrillin-1-positive fibers became thin and disappeared by 72 hr, while fibrillin-2-positive fibers disappeared almost completely within 24 hr. At 7 days of PDL fibroblast culture, fibrillin-1-positive fibers were mostly merged with fibrillin-2. After MMP-2 activation, fibrillin-1-positive fibers became thin by 24 hr and had almost disappeared by 48 hr, while fibrillin-2-positive fibers decreased constantly after 24 hr. A MMP-2 inhibitor completely suppressed these degradations. These results suggest that the patterns of fibrillin-1 and fibrillin-2 degradation differ between the eye and the PDL, possibly reflecting the sensitivity of fibrillin-1 and fibrillin-2 of each type of oxytalan fiber against MMP-2.

Crater-and-split technique for phacoemulsification: Modification of the crater-and-chop technique

We describe a modification of the crater-and-chop technique for removing cataracts of all densities. Following creation of a central crater approximately 3.0 mm in diameter at the geometric center of the endonucleus, a nucleus splitter is inserted under the capsule and the phaco tip is inserted in the crater. Simultaneously, the splitter is moved from the nucleus periphery toward the phaco tip horizontally to split the nucleus and both the phaco tip and nucleus splitter are pushed aside as they come very close without vacuum at any point. The nucleus is rotated and splitting is repeated in the same manner until the nucleus is divided into pieces that are small enough to be emulsified easily. With this technique, the soft nucleus is split without vacuum and a very hard nucleus can be split through the posterior plate with minimal stress to zonular fibers.

Extraction of lens geometry in an optomechanical eye model during accommodation using automatic image processing

AbstractPurpose To extract curvature, lens thickness and optical performance of accommodative intraocular lenses (AIOL) in an optomechanical eye model.Methods Freshly enucleated porcine eyes with an implanted AIOL and removed cornea were placed in a cuvette with BSS (35°C) simulating physiological conditions. The ciliary body was expanded radially symmetric to stretch or release the zonula fibers effectuating pseudophakic accommodation. Dynamic accommodation and imaging quality was measured with a Shack‐Hartmann‐Sensor (SHS). Shape and relative lens position during accommodation was measured with an optical coherence tomograph (OCT). The 3D OCT image was processed with denoising and edge detection extracting the AIOL surface. Remaining haptic data were eliminated. Images were corrected by inverse ray‐tracing for compensation of the OCT’s beam divergence and refractive effects of optical surfaces. Finally the AIOL geometry was derived by a spherical fit and the center thickness was determined.Results The algorithm allows to extract edge data from noisy OCT images and up‐to‐scale geometrical data. Curvature was derived from a fit of the edge points and relative lens position, lens thickness as well as optical power for the optomechanical eye model were measured at different states of accommodation. Optics with a diameter up to 6 mm could be measured with a lateral/depth resolution of 20/5 µm. The results yield complimentary data to the image quality measured with the SHS.Conclusion The algorithms are elementary tools for the setup of the optomechanical eye model for AIOL. It is now possible to evaluate different AIOL in an experimental setup as a base for development of next generation AIOL.

Effect of non-lethal H2O2-induced persistent oxidative injury on retinal pigment epithelial barrier

Background Reactive oxygen intermediate products lead to the oxidative injury of cells.Retinal pigment epithelial(RPE) cells produce lots of reactive oxygen intermediate products during the swallow of out disc,but how this procedure cause the persistent oxidative injury of RPE cells is poorly understood. Objective The present study was to evaluate the effect of non-lethal H2 O2 -induced persistent oxidative injury on RPE barrier in vitro.Methods ARPE-19 cell links were inoculated on 96 well plate at the density of 8×104 cells/L and the cell climbing slice of 24 well at the density of 4× 104 cells/L.The cells were cultured in DMEM/F12 medium,and the cells cultured for 24 hours in free-serum medium were used in the experiment.0-0.6 mmol/L of H2O2 were added into the medium.Cellular viability was assessed using 3- ( 4,5-dimethylthiazol-2-yl ) -5- ( 3-carboxymethoxyphenyl ) -2- ( 4-sulfophenyl ) 2H-tetrazolium(MTS) assays.Transepithelial electrical resistance (TER) was used to detect cell monolayer forming time after culture in Trsnswell chamber.The permeability of cell monolayer was examined by rhodamine isothiocyanate-dextran transepithelial flux,and immunofluorescence was used to investigate the distribution of the junction protein zonula occludens (ZO-1). Results The total difference was found in the cell vitality(A490) among the different concentrations of H2 O2 ( F =991.501,P =0.000 ).Compared with 0 mmoL/L H2 O2 group,the A490 values was gradually lowed from 0.20 mmol/L H2O2 group to 0.60 mmol/L H2O2 group (P ＜ 0.05 ).H2O2 at the concentrations of ＞0.20 mmol/L lowed the viability of RPE cells.The TER value was ( 24.9 ± 1.3 ) Ω · cm2 in 11 days,( 17.8± 1.4)Ω · cm2 in 7 days after inoculation on transwell chamber,showing a significant difference between them (t=5.228,P=0.014).RPE formed the stable tight junction on day 15 with the TER value (25.9±0.9 ) Ω · cm2.The leakage amount ( relative fluorescence intensity ) of the dextran was 255.39 ± 16.44 in non-H2 O2 control group,exhibiting a significant lowing in comparison with free-cell blank group (433.08±51.53)( t =12.515,P =0.006 ),and that of H2 O2 group was significant increased in comparison with non-H2 O2 control group ( t =14.412,P=0.005).Immunofluyorescence assay showed intact intercellular ZO-1 junction in non-H2O2 control group,but the breakage of ZO-1 junction was seen in H2O2 group. Conclusions The results indicate that non-lethal H2O2 can destroy RPE barrier and further lead to the persistent oxidative injury of RPE cells. Key words: H2O2; Retinal pigment epithelium; Oxidative stress; Tight junction

Analysis of tight junctions in placentas affected by chorioamnionitis: in vivo and in vitro analysis

The human placenta and fetal membranes provide a barrier regulating the transfer of materials between the mother and the developing fetus throughout gestation. Chorioamnionitis is an important risk factor for preterm delivery that is associated with high perinatal morbidity and mortality. Chorioamnionitis is the term applied to infections of the placenta and membranes resulting in high concentrations of IL- 1beta, IL-6, IL-8 and TGF-beta in the amniotic fluid (D’Alquen et al., 2005). With progression of inflammation, immune cells penetrate blood vessels and infiltrate the umbilical cord, resulting in funisitis (Romero and Mazor, 1988). In normal conditions the two important physical entities in endothelial/epithelial paracellular clefts are adherens junctions and tight junctions. Tight junction governs the paracellular movement of water, solutes and immune cells, through the intercellular space creating a boundary between the apical and basolateral sides of cellular barriers (Gruenheid and Finlay, 2003). We have evaluated the localization of tight junctions studying the Zonula Occludens-1 (ZO-1) and Occludin expressions as well as the localization of adherent junctions, testing the expression of VE-cadherin and beta-catenin in placentas from normal gestations, from preterm idiopathic deliveries and from chorioamnionitis by immunohistochemistry. In addition, we have evaluated the mRNAs by real time PCR, the protein levels of these molecules by Western blot analysis in placental tissues, and to better clarify the action of some cytokines on occludin we performed in vitro analysis of HUVEC cultures. Our more striking result is the decrease of occludin expression in placentas from chorioamnionitis and an evident action of the cytokines on this molecule.

Urbach-Wiethe Syndrome and the Ophthalmologist: Review of the Literature and Introduction of the First Instance of Bilateral Uveitis

Patients suffering from Urbach-Wiethe syndrome (UWS), also known as lipoid proteinosis or hyalinosis cutis et mucosae, may have an ophthalmologist involved in the diagnosis and management of their disease. Along with moniliform blepharosis as a pathognomonic feature of the disease, an ophthalmologist may encounter other manifestations of UWS in any part of the eye such as cornea; conjunctiva; sclera; trabecular meshwork; iris/pupil; lens and zonular fibers; retina; nasolacrimal duct. This paper provides a review on the pathogenesis and the diverse ocular manifestations seen in UWS patients. Uncommon complications are discussed in this paper (glaucoma; dry eye and epiphora; complications of lens, retina, cornea; iris/pupil and conjunctiva). Moreover, a 27-year-old male UWS patient is described with bilateral diffuse anterior stromal iris atrophy, diffuse keratic precipitates; posterior subcapsular cataract; 1 + vitreous cell in anterior vitreous examination. This case was thought to be the first instance of bilateral uveitis associated with UWS. Overall, ophthalmologists may encounter diverse ocular complications accompanying this syndrome. They should be familiar with well-established ophthalmologic manifestations leading them to cooperate with other specialists in diagnosis and management of the disease.

Surveillance program on and the distribution related to the virulence-associated genes of Vibrio cholerae in estuary of Pearl River

To understand the distribution, molecular characteristics and virulence genes of the O1 and O139 Vibrio cholerae isolates from the Pearl River Estuary water. Vibrio cholerae isolates collected from the Pearl River estuary waters from January 2009 to December 2010, were tested by PCR for eight virulence-related genes, including cholera toxin (ctxA), zonula occludens toxin (zot), accessory cholera enterotoxin (ace), hemolysin (hlyA), toxin-coregulated pilus (tcpA), outer membrane protein (ompU), and the regulatory protein genes (tcpI, toxR). Genetic relation was assessed by pulsed-field gel electrophoresis (PFGE) and the patterns were clustered by BioNumerics. From 1152 aquatic samples, 69 isolates were identified, including 41 Inaba, 18 Ogawa and 10 O139. All the isolates showed ctxA negative, while the hlyA and toxR genes were positive in all the isolates. 34.15% (14/41) of the Inaba strains were hlyA(+) toxR(+) ompU(+) ace(+) zot(+) tcpI(+), while 66.67% (12/18) belonged to Ogawa strains and 70% (7/10) of the O139 strains were hlyA(+) toxR(+). Through PFGE analysis, the O1 isolates formed three clusters in this study. The patterns of O1 isolates differed widely, with the similarity as 72.8% - 100.0%, while the patterns of O139 isolates having the similarity of 69.9% - 95.5%. The non-toxigenic O1 and O139 V. cholerae had a wide distribution in the environment of Pearl River estuary water during the non-epidemic period of cholera. All the aquatic isolates presented diversities on the related virulent genes.

High concentration bile changes the chloride channel protein-2 and permeability of intestinal epithelium cell line

Objective To investigate the effects of bile on chloride channel protein-2 (CLC-2)and permeability of intestinal epithelium cell.Methods Rat intestinal epithelium cell line IEC-6 was cultured.They were exposed to 5.0％,1.0％,0.1％ rat bile and chloride channel agonist Lubiprostone.After 20 h cultured,transepithelial electrical resistance (TER) of the monostratal cells was measured.The change of CLC-2 and zonula occludens-1 (ZO-1) were examined by Western blotting,and the images were analysed quantitatively.Results The TEER of 5％ group was most lower.The average relative gradations of Western blotting images in 5.0％ group and 1.0％ were lower obviously than those in control group (0.30 ± 0.05,0.37 ± 0.08 vs.0.56 ± 0.08) ( all P ＜ 0.05 ).The relative gradations of ZO-1 were decreaseded only in 5.0％ group.After Lubiprostone added,the TER in 5.0％ group was upgraded (451.3 ± 60.5 )Ω·cm2,and the average relative gradations of ZO-1 (0.32 ± 0.04).Conclusion High concentration of bile destroied enterocyte chloride channel and tight junction protein,increase epithelium permeabihty. Key words: Bile; Enterocyte; Chloride channel protein-2 ; Permeabihty

Numerical Modeling of Paintball Impact Ocular Trauma: Identification of Progressive Injury Mechanisms

To create a computer-based numerical simulation model for comparison with empiric paintball-ocular ballistic study findings, allowing identification of the dynamic physical mechanisms (stress, strain, pressure) responsible for intraocular traumatic injury accompanying blunt ocular impact. Virtual experiments with numerical models could exploit mathematical "instrumentation" to facilitate internal observation impossible with physical experiments alone. Models of human eye structures and orbit were implemented into the finite-volume Eulerian numerical hydrocode CTH. Numerical simulation results were compared with dynamic imaging and postimpact histopathology obtained during previous ballistic impact experiments on fresh porcine eyes impacted with paintballs. Forty numerical simulations and 59 impact experiments were conducted as part of the study. Time-lapse correlations showed the CTH models to be dynamically commensurate with orbital penetration and globe deformation measured from ballistic high-speed videos. CTH also predicted the types and levels of damage observed in detailed postimpact pathologic assessments of porcine specimens. High strain in the ciliary body and zonule corresponded with angle recession and lens displacement pathologically. Globe rupture was attained at the highest paintball impact velocities in both the porcine ballistic studies and CTH models, consistent with predicted dynamic intraocular pressures. The simulations also revealed that phenomena such as macular Berlin's edema, midperipheral retinoschisis, and choroidal and retinal detachment might be explained by focal dynamic pressure-wave reflection from the interior surface of the globe. Significant insight was gained regarding the physical mechanisms responsible for injury. CTH predictions corresponded closely with previous ballistic experimental results, adding intraocular detail otherwise unattainable.

Preoperative and postoperative size and movements of the lens capsular bag: Ultrasound biomicroscopy analysis

To evaluate capsular bag size and accommodative movement before and after cataract surgery using ultrasound biomicroscopy (UBM) and anterior segment optical coherence tomography (AS-OCT). Ophthalmology Unit, Fabia Mater Clinic, Rome, Italy. Cohort study. Eyes having cataract surgery and monofocal intraocular lens (IOL) implantation were studied using UBM. The following parameters were measured preoperatively and 1, 2, and 12 months postoperatively: anterior chamber depth (ACD) (also by AS-OCT), capsular bag thickness, capsular bag diameter, ciliary ring diameter, sulcus-to-sulcus (STS) diameter, ciliary process-capsular bag distance, ciliary apex-capsular bag plane, and IOL tilting. The preoperative and postoperative capsular bag volumes were calculated at 12 months. The results were compared with the changes during accommodation. The study comprised 24 eyes. With the exception of the ciliary apex-capsular bag plane, which appeared to be unmodified postoperatively, all measured parameters showed significant variation after IOL implantation. Only the ACD did not change significantly during accommodation. After cataract surgery, the capsular bag stretched horizontally and with reduced vertical diameter as a result of adaptation to the implanted IOL. The capsular bag-IOL complex filled all available space, compressing the zonular fibers and almost abolishing the space between the ciliary apex and the capsular bag. There was anterior chamber deepening and a decrease in the ciliary ring diameter and STS diameter. In the absence of zonular fiber tension, the shape of the ciliary processes may be modified. No author has a financial or proprietary interest in any material or method mentioned. Additional disclosures are found in the footnotes.

Surgery of ectopia lentis

AbstractPurpose Ectopia lentis is a patology with lens dislocation presumably secondary to zonular fiber weakness. Ectopia lentis can occur in isolation, in association with other ocular disorders or as part of systemic disorder. Marfan´s syndrome and homocystinuria are the most frequent cause of heritable ectopia lentis. Marfan syndrome (MFS) is a hereditary connective tissue disorder. Studies of MFS have established the critical contribution of fibrillin‐1 deficiency to disease progression through altered cell‐matrix interactions and dysregulated TGF‐β signalling.Methods We report four eyes of 4 children aged from 2 years to 4 years with ectopia lentis Both cases showed bilateral and symmetric lens dislocation with low visual acuity. One of the children was diagnosed of Marfan syndrome.Results We practised Twenty three gauge two port pars plana lensectomy without intraocular lenses.Conclusion Pars plana lensectomy is a safe, effective procedure for the management of ectopia lentis. Earlier surgery is indicated to prevent amblyopia and improve visual acuity. Marfan syndrome, homocystinuria, trauma and simple ectopia lentis are the most common caused of pediatric lens subluxation. Ectopia lentis in children continues to be a diagnostic and therapeutic challenge for ophthalmologists. The convencional surgical management of congenital subluxated lenses infrequently associated with a high incidence of complications leading to poor visual prognosis. Surgical intervention is necessary when lens subluxation causes a significant refractive error resulting in amblyopia.

Simulation platform for evaluation of geometrical and positional changes of lenses during accommodation

AbstractPurpose To build‐up an optomechanical eye model to reproduce physiological accommodation as a test environment for assessment of accommodative intraocular lenses (AIOL).Methods Freshly enucleated porcine eyes were cleaned and glued into an expansion unit at ciliary body level. The cornea was removed using a trephine. After extraction of the crystalline lens with circular capsulorhexis an AIOL was implanted into the capsular bag. Finally, the posterior part of the globe was cut off and a vitrectomy was performed. The expansion unit with the dissected eye was placed in a temperature stabilized cuvette with BSS (35°C) simulating physiological conditions. The ciliary body is expanded to stretch or relax the zonula fibers effectuating pseudophakic accommodation. For a dynamic measurement of accommodation we used: 1) A Shack‐Hartmann‐Sensor for measuring optical performance. 2) An optical coherence tomograph (OCT) to measure the shape and relative lens position during accommodation.Results The setup allows measurement of curvature, relative lens position, optical power and image quality of the IOL for different states of accommodation. Due to optical constraints, simultaneous measurement of 1) and 2) was not possible. Therefore, the cuvette was shifted between both beam paths for each measurement. Within the measurement area (5.5 x 5.5 x 1.6 mm in air) the OCT resolution is limited to 12 µm.Conclusion The presented setup was considered to analyze the behavior of AIOL during accommodation in terms of change in curvature, position and optical performance. After experimental evaluation of the setup we will standardize and automate the measurement procedure, with the goal of a new AIOL design.

Fibrillin-1 and Fibrillin-2 Are Essential for Formation of Thick Oxytalan Fibers in Human Nonpigmented Ciliary Epithelial Cells In Vitro

The ciliary zonule, also known as Zinn’s zonule, is composed of oxytalan fibers. However, the mechanism by which epithelial cells in the ciliary body form these fibers in not fully understood. We examined human nonpigmented ciliary epithelial cells to determine the appearance and amount of oxytalan fibers in terms of positivity for their major components, fibrillin-1 and fibrillin-2. Examination of fibrillin-1 and fibrillin-2 expression by immunofluorescence revealed that thin fibers positive for fibrillin-1 on Day 2 changed to thick fibers by Day 8. The fibers positive for fibrillin-2 appeared on the thick fibrillin-1-positive fibers after Day 4. Northern blot analysis revealed that the level of fibrillin-1 did not change markedly, while induction of fibrillin-2 gene was evident on Day 5. Western blot analysis showed that fibrillin-1 deposition increased gradually, while that of fibrillin-2 increased markedly from Day 5 to Day 8. Fibrillin-1 suppression did not lead to the formation of fibrillin-2-positive thick fibers, whereas fibrillin-2 suppression led to the formation of fibrillin-1-positive thin fibers, but not thick fibers. These results suggest that both fibrillin-1 and fibrillin-2 are essential for the formation of thick oxytalan fibers in the ciliary zonule and are informative for clarifying the mechanism of homeostasis of the ocular matrix.

Beidseitiger Zonulafaserdefekt

Anterior segment colobomas can be found isolated or in combination with changes in the posterior segment. A coloboma of the ciliary zonule leads to alteration of the lens profile with myopia and astigmatism. Amblyopia and cataract development may also occur. We present two cases with a coloboma of the zonule with different degrees of expression and the most important differential diagnoses are discussed.

Modified sutureless small-incision non-phacoemulsification extracapsular cataract surgery in high myopia with cataract

Objective To evaluate the clinical efficiency and safety of the modified sutureless small-incision non-phacoemulsification extracapsular cataract surgery in high myopia. Methods This study comprised 56 highly myopic cataract patients (70 eyes). Continuous curvilinear capsulorhexis, hydrodissection and hydrodelineation, assisting nucleus-chop, and irrigation/aspiration procedures were performed through an extra constructed auxiliary incision to maintain more stable anterior chamber and facilitate the manipulation during surgery. Furthermore, low flow and the protection of viscoelastic material made cortex aspiration thoroughly and more safely. Results 58 axial length ＜ 30 mm eyes, the best correctted visual acuity (BCVA) exceeded 0.5 in 45 eyes (80.36%) at 1 month of follow-up. Among 12 axial length≥30 mm eyes, the BCVA exceeded 0. 3 in 7 eyes (58.33%). Corneal curvature kept unchangeable after surgery. No intraoperative or postoperative complications such as posterior capsule rupture, zonules as well as iris and cornea injury occurred. Conclusion The modified sutureless small-incision non-phacoemulsification extracapsular cataract surgery was safe and with more efficiency in high myopia. Key words: high myopia; modified; small-incision; non-phacoemulsification