Lens Injury Research Articles

RGMA and neogenin protein expression are influenced by lens injury following optic nerve crush in the rat retina

The death and the failure of neurons to regenerate their axons after lesion of the central nervous system in mammals, as in the case of spinal cord injury and optic nerve trauma, remain a challenge. In this study, we focused on the repulsive guidance molecule A (RGMA) and its receptor neogenin. Since it was reported that RGMA+ cells accumulate in lesioned areas after spinal cord injury, brain trauma, and optic nerve crush, and curiously, anti-apoptotic effects of RGMA were also described, we investigated the role of RGMA and neogenin in the retina after optic nerve crush (ONC). We evaluated the spatial and temporal protein pattern of RGMA and neogenin in the rat retina without (non-regenerating model) or with (regenerating model) lens injury (LI). We investigated the presence of RGMA, neogenin and other proteins at up to nine time points (6 h-20 days post-surgery) by performing immunohistochemistry and Western blots. Independent of the treatment, RGMA protein was present in the nuclear layers (NLs), plexiform layers (PLs), nerve fiber layer (NFL), and in retinal ganglion cells (RGCs) of the rat retina. RGC and nerve fibers were always RGMA+. Further RGMA+ cells in the retina were blood vessel endothelial cells, astrocytes, Müller cells, and some microglial cells. The RGMA pattern for the specific retinal cells resembled those of previously published data. The neogenin pattern was congruent to the RGMA pattern. Western blots of retinal tissue showed further RGMA+ products only in LI animals. Furthermore, a higher amount of RGMA was found in the retinae of ONC + LI rats compared to ONC rats. Although a difference in the localization of RGMA is not obvious, the difference in the amount of RGMA is striking, the higher amount of RGMA in the retinae of ONC + LI rats compared to ONC rats indicates a role for RGMA during degeneration/regeneration processes. Our results are consistent with several reported neuroprotective effects of RGMA. Our new data showing the upregulation of RGMA after ONC in our regenerating model (plus LI) confirm these findings conducted in different settings.

Axonal tracing of the normal and regenerating visual pathway of mouse, rat, frog, and fish using manganese-enhanced MRI (MEMRI)

To assess optic nerve (ON) regeneration after injury by applying manganese-enhanced MRI (MEMRI) in a study of comparative physiology between nonregenerating rat and mouse species and regenerating frog and fish species. The normal visual projections of rats, mice, frogs, and fish was visualized by intravitreal MnCl(2) injection followed by MRI. Rats and mice with ON crush (ONC) were divided into nonregenerating (ONC only), and regenerating animals with peripheral nerve graft (ONC+PNG; rats) or lens injury (ONC+LI; mice) and monitored by MEMRI at 1 and 20 days post-lesion (dpl). Frog and fish with ON transection (ONT) were monitored by MEMRI up to 6 months postlesion (mpl). Signal intensity profiles of the Mn(2+)-enhanced ON were consistent with ON regeneration in the ONC+PNG and ONC+LI rat and mice groups, respectively, compared with the nonregenerating ONC groups. Furthermore, signal intensity profiles of the Mn(2+)-enhanced ON obtained between 1 mpl and 6 mpl in the fish and frog groups, respectively, were consistent with spontaneous, complete ON regeneration. Taken together, these results demonstrate that MEMRI is a viable method for serial, in vivo monitoring of normal, induced, and spontaneously regenerating optic nerve axons in different species.

Neurite Outgrowth of Mature Retinal Ganglion Cells and PC12 Cells Requires Activity of CK1δ and CK1ε

Mature retinal ganglion cells (RGCs) do not normally regenerate severed axons after optic nerve injury and show only little neurite outgrowth in culture. However, RGCs can be transformed into an active regenerative state after lens injury (LI) enabling these neurons to regrow axons in vitro and in vivo. In the current study we investigated the role of CK1δ and CK1ε activity in neurite outgrowth of LI stimulated RGCs and nerve growth factor (NGF) stimulated PC12 cells, respectively. In both cell types CK1δ and ε were localized in granular particles aligned at microtubules in neurites and growth cones. Although LI treatment did not measurably affect the expression of CK1δ and ε, it significantly elevated the specific kinase activity in the retina. Similarly, CK1δ/ε specific kinase activity was also elevated in NGF treated PC12 cells compared with untreated controls. Neurite extension in PC12 cells was associated with a change in the activity of CK1δ C-terminal targeting kinases, suggesting that activity of these kinases might be necessary for neurite outgrowth. Pharmacological inactivation of CK1δ and ε markedly compromised neurite outgrowth of both, PC12 cells and LI stimulated RGCs in a concentration dependent manner. These data provide evidence for a so far unknown, but essential role of CK1 isoforms in neurite growth.

WE‐F‐110‐01: Radiation & Cataract: A New Challenge

We are passing through an era wherein it is certain that the currently accepted threshold for radiation cataract is no longer valid. Radiation cataract has, to date, been considered a deterministic effect with threshold. The International Commission on Radiological Protection (ICRP) has published threshold values for detectable opacities of 5 Gy for chronic and 0.5–2.0 Gy for acute exposures. A number of studies in staff involved in interventional procedures, in particular cardiology and other radiation exposed populations, including astronauts, atomic bomb survivors, X‐ray technologists and clean‐up workers in Chernobyl, have indicated that there is an increased incidence of lens opacities at doses below 1 Gy. The higher workload that is typical now in many cath labs, a lack of training in radiation protection and non‐availability or non‐use of radiation protection devices can result in doses to the eye lens that are high enough to cause lens injuries. International Atomic Energy Agency (IAEA) had launched a project to test the eyes of interventional cardiologists and support staff and results have been published in two papers in 2010. Further there have been publications in 2010 on the efficacy of various shielding strategies for protection of the operatorˈs eyes in the interventional suits. Leaded glasses, scatter‐shielding drapes and leaded shields were evaluated in various combinations and in different (characteristic) operator positions. It is reported that the use of leaded glasses alone reduced the lens dose rate by a factor of five to 10, while scatter‐shielding drapes alone reduced the dose rate by a factor of five to 25. Using both eye‐shielding implements together reduced the dose rate by a factor of 25 or more, and always proved more protective than either used alone.The talk will review the basic information about radiation catactogenesis, epidemiological information and results of recent studies.Learning Objectives:1. To understand the basic information about radiation cataractogenesis2. To understand the efficacy of protective tools3. To become aware about the likely changes in current recommendation that may be brought up by international bodies such as the ICRP.

Dietary vitamin C and E modulates oxidative stress induced‐kidney and lens injury in diabetic aged male rats through modulating glucose homeostasis and antioxidant systems

Diabetes induces oxidative stress in aged human and rat, although daily supplementation of vitamins C and E (VCE) can be beneficial to aged diabetic rats by reducing free radical production. The aim of the present study was to evaluate whether dietary VCE supplementation relieves oxidative stress in streptozotocin (STZ)-induced diabetic in aged rats. Thirty aged rats were randomly divided into three groups. The first group was used as a control. The second group was made diabetic using a single dose of intraperitoneal STZ. VCE-supplemented feed was given to aged diabetic rats constituting the third group. On the 21st day of the experiment, blood, lens and kidney samples were taken from all animals. Glutathione peroxidase (GSH-Px) activity in lens and kidney, reduced glutathione (GSH), vitamin E and β-carotene concentrations in kidney were lower in the diabetic group than in the control whereas plasma glucose, urea and creatinine, and kidney and lens peroxidation (LP) levels were higher in the diabetic group than in the control. However, kidney and lens LP levels, and plasma glucose, urea and creatinine values were decreased by VCE supplementation. Lens and kidney GSH-Px activity, kidney GSH, vitamin E and β-carotene concentrations and erythrocyte counts were increased by VCE treatment. Kidney weights, vitamin A, haemoglobin, hematocrit, leukocyte and platelets values were not changed by diabetes and/or VCE supplementation. VCE ameliorated also diabetes-induced histopathological changes in kidney. In conclusion, we observed that VCE supplementation is beneficial towards kidney and lens of aged diabetic rats by modulating oxidative and antioxidant systems.

Posterior capsular rupture, lens dislocation and absorption after blunt trauma

In most contusional injuries of the eye, the anterior segment bears the brunt of both direct and indirect forces. The iris, filtration angle, lens and zonules are particularly vulnerable. Most studies of ocular contusion relate to specific sequelae, for example, traumatic hyphaema, anterior chamber angle recession, lens injury and blood staining of the cornea. Lens injury is a major complication of blunt trauma and is seen in 30 to 65 per cent of cases. Commonly described lens changes following blunt trauma are contusion cataract and partial or total dislocation. Here we report a rare case of isolated posterior capsular rupture, and nucleus dislocation and absorption following blunt trauma, while the anterior capsule remained intact, which to the best of our knowledge has never been reported. CASE REPORT

Taxol Facilitates Axon Regeneration in the Mature CNS

Mature retinal ganglion cells (RGCs) cannot normally regenerate axons into the injured optic nerve but can do so after lens injury. Astrocyte-derived ciliary neurotrophic factor and leukemia inhibitory factor have been identified as essential key factors mediating this effect. However, the outcome of this regeneration is still limited by inhibitors associated with the CNS myelin and the glial scar. The current study demonstrates that Taxol markedly enhanced neurite extension of mature RGCs and PC12 cells by stabilization of microtubules and desensitized axons toward myelin and chondroitin sulfate proteoglycan (CSPG) inhibition in vitro without reducing RhoA activation. In vivo, the local application of Taxol at the injury site of the optic nerve of rats enabled axons to regenerate beyond the lesion site but did not affect the intrinsic regenerative state of RGCs. Furthermore, Taxol treatment markedly increased lens injury-mediated axon regeneration in vivo, delayed glial scar formation, suppressed CSPG expression, and transiently reduced the infiltration of macrophages at the injury site. Thus, microtubule-stabilizing compounds such as Taxol might be promising candidates as adjuvant drugs in the treatment of CNS injuries particularly when combined with interventions stimulating the intrinsic regenerative state of neurons.

Current progress in pathogenesis and prevention of hyperoxia-induced ocular injury

Hyperoxia, including hyperbaric oxygen (HBO) and high-concentration oxygen (HO), has an important therapeutic effect on various ophthalmological diseases, such as retinal vein occlusion, ischemic optic neuropathy and central serous chorioretinopathy. However, excessive inhalation of oxygen of high-concentration or high atmospheric pressure can cause damage of ocular tissue, in which the lens opacity and retinopathy of prematurity (ROP) are the most common complications following hyperoxia exposure. At present, the pathogenesis of hyperoxia-induced ocular injury is still unclear thoroughly, and it may be related to oxidative stress, lipid peroxidation and inflammation. This article reviewed the current advance in the mechanism and the potential prevention of hyperoxia-induced the lens,retina and other ocular injuries. Key words: Hyperoxia; Oxidative stress; Lipid peroxidation; Lens; Retina

Different spatial and temporal protein expressions of repulsive guidance molecule a and neogenin in the rat optic nerve after optic nerve crush with and without lens injury

The failure of lesioned mammalian CNS neurons to regenerate their axons remains a challenge. Evidence is emerging that repulsive proteins contribute to this failure. The repulsive guidance molecule A (RGMA) induces growth cone collapse in vitro, accumulates in the scar after spinal cord injury, and is up-regulated in glaucoma. In this study, we evaluated the spatial and temporal localization pattern of RGMA and its receptor neogenin in the optic nerve after optic nerve crush (ONC) without or with lens injury (LI) at up to nine time points (6 hr to 20 days) postsurgery by performing immunohistochemistry and Western blots. We found RGMA at the crush site (CS) and in the developing scar of ONC rats at every time point investigated, whereas it was absent in the CS of ONC + LI rats. Independent of the model, many cells were RGMA(+) in the ON: nerve fibers, blood vessels, astrocytes, oligodendrocytes, some microglia, some macrophages, and the sheath of the ON. Western blots showed a significantly lowered amount of RGMA in ONC + LI animals at 2, 4, and 6 days after crush compared with ONC animals. Furthermore, LI in sham-operated animals showed an increase of RGMA in six of eight time points compared with the sham-operated animals. Moreover, the effects of LI on the morphology of the ON were characterized at a level of detail never reported before. Our results show that RGMA is present and might contribute to the inhibitory environment in the ON, especially in and around the CS after ONC.

Descemet’s Stripping with Endothelial Keratoplasty for Special Fuchs’ Endothelial Dystrophy in Phakic Eyes

Background: To determine the efficacy and postoperative complications of simple Descemet’s stripping endothelial keratoplasty (DSEK) for treatment of special Fuchs’ endothelial dystrophy in phakic eyes. Methods: Six eyes with clear crystalline lenses in 5 consecutive patients with Fuchs’ endothelial dystrophy underwent DSEK and were followed up for 12–27 months. The pupil was constricted preoperatively to 1.5 mm in diameter. The anterior chamber was deepened intraoperatively by injection of balanced salt solution to unfold the donor graft and to protect the crystalline lens. Best corrected visual acuity, corneal astigmatism, corneal curvature, corneal thickness, and anterior chamber depth were recorded preoperatively and at 6 and 12 months postoperatively. Average endothelial cell density and endothelial cell loss (ECL) were recorded at 6 and 12 months postoperatively. Results: DSEK was successfully performed in all 6 eyes. No graft dislocation or lens injury occurred. One of the 6 eyes presented with mild cataract at 12 months after surgery but showed no sign of progressive cataract development during the follow-up. All grafts were clear during the last follow-up: best corrected visual acuity ranged from 20/50 to 20/30, average corneal astigmatism was 2.2 ± 0.6 dpt, average corneal curvature was 46.0 ± 2.4 dpt, and average central corneal thickness was 583.0 ± 21.5 µm. At 6 and 12 months postoperatively, average endothelial cell density was 2,070.7 ± 206.1 cells/mm² (28.0 ± 7.5% of ECL) and 1,838.3 ± 194.5 cells/mm² (36.1 ± 6.2% of ECL), respectively. Conclusions: Simple DSEK might be a feasible option for Fuchs’ endothelial dystrophy in young patients with clear crystalline lenses.

Stromal Cell-Derived Factor-1 Is Essential for Photoreceptor Cell Protection in Retinal Detachment

Stromal cell-derived factor-1 (SDF-1) causes chemotaxis of CXCR4-expressing bone marrow-derived cells. SDF-1 is involved in the pathogenesis of various vascular diseases, including those of the eye. However, the role of SDF-1 in neuronal diseases is not completely understood. Here, we show higher SDF-1 levels in the vitreous humor of patients with retinal detachment (RD) compared with normal patients. SDF-1 correlated positively with the duration as well as the extent of RD. Furthermore, SDF-1 correlated significantly with levels of interleukin-6 and interleukin-8, but not with vascular endothelial growth factor. Western blot analysis results showed significant SDF-1 up-regulation in detached rat retinas compared with normal animals. Immunohistochemistry data showed that SDF-1 was co-localized with the glial cells of the detached retina. SDF-1 blockade with a neutralizing antibody increased photoreceptor cell loss and macrophage accumulation in the subretinal space. The retinal precursor cell line R28 expressed CXCR4. SDF-1 rescued serum starvation-induced apoptosis in R28 cells and enhanced their ability to participate in wound closure in a scratch assay. Our results indicate a surprising, protective role for SDF-1 in RD. This effect may be mediated directly or indirectly through other cell types.

Assessment of fatigue in intraocular surgery: analysis using a virtual reality simulator

To determine the effect of fatigue on intraocular surgical performance using a virtual reality simulator. Seven experienced ophthalmic surgeons were recruited. The first set of data collection was immediately before a live theatre session. Each surgeon received a standardized orientation to a virtual reality cataract surgery simulator (Eyesi©, VRmagic, Mannheim, Germany). All surgeons then completed ten attempts on level-four forceps module. The parameters recorded were total score, total time, total time score, corneal injury score, lens injury score, odometer score, and operating without red reflex score. To reduce the effect of the learning curve, each surgeon had a "plateau" score calculated for every parameter, which was the average of their final four attempts. The surgeons then returned immediately after their scheduled theatre lists to complete a further ten attempts on the same module and similar parameters were recorded. Following routine theatre lists, simulator parameters slightly improved, with only the total score (97.28 to 98.57, p = 0.028) and total time (44 s to 35 s, p = 0.033) being statistically significant. The mean theatre list operating time was 197 min (SD ± 23.60). No detrimental effect of fatigue was demonstrated following a routine operating list. The study provides a template for further assessments of fatigue in high-volume cataract surgery lists.

Incidence of Damage to the Crystalline Lens During Intravitreal Injections

To report the incidence of traumatic lens injuries as a complication of intravitreal injection at 5 high-volume academic centers. We determined in a retrospective, interventional, multicenter case series the consecutive number of the injections between January 5, 2006 and December 22, 2008 from the injection log books. All injections were performed under sterile conditions in a laying position, 3.5-4.0 mm behind the limbus in an oblique fashion. The main outcome measure was the incidence of lens damage. A total of 32,318 intravitreal injections were performed, and 3 cases of iatrogenic lens damage were reported during 36 consecutive months. All affected eyes were hyperopic. The overall incidence rate of lens injury was 0.006% (2/32,318) for intravitreal injections and 1 during a paracentesis 0.003 (1/32,318). The rate of phakic eyes determined was 67%, and thus, the incidence rate of lens damage in phakic eyes was 0.009% (2/21,653) (95% confidence interval, 0.00%-0.05%). Although there is no agreement regarding the proper intravitreal injection technique, the incidence of traumatic injuries to the crystalline lens was very low in a large series of injected patients in a community setting. The incidence compares favorably with that reported in clinical trials in which much more extensive preinjection preparation was mandated. A good preparation of the surgical incision with proper anesthesia and detailed information of the patient, as well as good anatomical skills of the treating physician, are mandatory to prevent this rare adverse event.

Prognostic Factors After Repair of Open Globe Injuries

Background: To identify prognostic factors for visual acuity and anatomic outcomes after repair of open globe injuries. Methods: We retrospectively reviewed the medical records of 443 patients with open globe injuries admitted to King Abdulaziz University Hospital between May 1996 and January 2008. Results: Predictors of good visual outcome (20/200 or better) were age of 18 years or younger, good initial visual acuity of counting fingers or better, sharp mechanism of injury, wound length of 10 mm or less, wounds limited to the cornea, absence of associated ocular injuries at presentation including lens injury, vitreous hemorrhage, vitreous prolapse and retinal detachment, absence of endophthalmitis, vitrectomy not performed, and findings at final evaluation including clear vitreous, attached retina, and absence of hypotony. Predictors of persistent retinal detachment at final evaluation were poor initial visual acuity of hand motions or worse, posterior wound location, and performance of vitrectomy. Predictors of hypotony at final evaluation were poor initial visual acuity of hand motions or worse, dirty wound, presence of vitreous hemorrhage, and vitreous prolapse at presentation, development of culture-positive endophthalmitis, performance of vitrectomy, and persistent retinal detachment at final follow-up. Conclusions: Prognosis after repair of an open globe injury is influenced by age, initial visual acuity, mechanism of injury, location and extent of initial damage, and development of endophthalmitis.

Sciatic nerve conditioning lesion increases macrophage response but it does not promote the regeneration of injured optic nerves

Injured optic nerves in the matured central nervous system (CNS), alike injured neurons in other CNS regions, fail to regenerate. Interestingly, activation of inflammatory cells (macrophages) following optic lens injury or implantation of peripheral nerve fragments into the vitreous body, have been previously reported to stimulate retinal ganglion cells (RGCs) to regenerate axons across the injury site and into the distal optic nerve. In addition, the beneficial role of macrophage cells has also been demonstrated in the regeneration of lesioned spinal neurons following sciatic nerve injury. However, it is not known whether these locally activated macrophage cells also contribute to the regeneration of remotely injured neurons within the CNS. Adult Sprague Dawley rats received a conditioning sciatic nerve injury followed by an optic nerve crush (ONC). Retrograde and anterograde tracing results revealed that injured optic axons did not regenerate after peripheral dorsal root ganglion (DRG) lesion, as the beneficial effects of this injury extended only locally. However, a greater inflammatory infiltration/activation was found in injury-combined animals compared to controls, although this was not sufficient to trigger a systemic regenerative response. Proximity of cell body response to injury, accompanied by a timely macrophage activation are critical factors for regeneration of injured CNS neurons to occur. Immune cell surveillance into the CNS compartment was enhanced following peripheral nerve injury. Scope: nervous system development, regeneration and aging.

Application of modified antegrade labelling method of rhodmine-B-isothiocyanate in study of optic nerves regeneration

目的 研究大鼠视神经再生中罗丹明B异硫氰酸盐(RITC)顺行标记改良法的标记效果.方法 52只Wistar大鼠随机分为3组:正常组(n=4)、单纯RITC注射组(n=24)和晶状体损伤组(n=24).正常组大鼠未作任何处理;单纯RITC注射组大鼠行单纯RITC眼玻璃体内注射;晶状体损伤组大鼠视神经完全性横断并对位缝合,同时损伤晶状体,形成白内障,促进视神经再生.各组大鼠定期进行眼部临床检查.对于单纯RITC注射组和晶状体损伤组,分别于注射后或术后1、3、5周时随机处死各组中的8只大鼠.正常组和单纯RITC注射组大鼠进行常规病理及透射电镜检查.晶状体损伤组于处死动物3 d前玻璃体内注入RITC以进行视神经的顺行标记,采用传统方法及改良法对比观察视神经轴突的再生情况.其中改良法是把观察RITC荧光的常规绿色激发光改为蓝色激发光,直接观察整个视路的荧光情况.结果 各组大鼠视神经RITC顺行标记荧光非常清晰,容易辨认.单纯RITC注射组所有大鼠在观察期间,眼部的临床观察和常规病理学及透射电镜检查均未发现任何不良反应.正常组与单纯RITC注射组各时间点间比较,差异无统计学意义(F=0.877,P=0.465).晶状体损伤组大鼠视神经再生率传统方法与改良法比较,1周时差异有统计学意义(χ2=6.788,P=0.009),3周和5周时差异均无统计学意义(χ2=2.667,P=0.220; χ2=1.143,P=0.600).结论 RITC视神经顺行标记改良法为一种观察视神经轴突再生较好的方法,具有灵敏度高、安全等优点。

Endoscopy-guided vitreoretinal surgery following penetrating corneal injury: a case report

Severe ocular trauma requires emergency surgery, and a fresh corneal graft may not always be available. We describe a case of perforating eye injury with corneal opacity, suspected endophthalmitis, and an intraocular foreign body. The patient was successfully treated with a two-step procedure comprising endoscopy-guided vitrectomy followed by corneal transplantation. This surgical technique offers a good option to vitrectomy with simultaneous keratoplasty in emergency cases where no graft is immediately available and there is the possibility of infection due to the presence of a foreign body. A 55-year-old Japanese woman was referred to our hospital with a perforating corneal and lens injury sustained with a muddy ferrous rod. Primary corneal sutures and lensectomy were performed immediately. Vitreoretinal surgery was required due to suspected endophthalmitis, vitreous hemorrhage, retinal detachment, dialysis and necrosis of the peripheral retina. Instead of conventional vitrectomy, endoscopy-guided vitreous surgery was performed with the Solid Fiber Catheter AS-611 (FiberTech, Tokyo, Japan) due to the presence of corneal opacity and the unavailability of a donor cornea. The retina was successfully attached with the aid of a silicon oil tamponade. Following removal of the silicon oil at 3 months after surgery, penetrating keratoplasty and intraocular lens implantation with ciliary sulcus suture fixation were performed. At 6 months after penetrating keratoplasty, the graft remained clear and visual acuity was 20/40. Primary endoscopic surgery for vitreoretinal complications in eyes with perforating injury performed prior to penetrating keratoplasty appears to be advantageous in terms of avoiding damage to the corneal endothelium.

Unique precursors for the mesenchymal cells involved in injury response and fibrosis

We investigated an alternative pathway for emergence of the mesenchymal cells involved in epithelial sheet wound healing and a source of myofibroblasts that cause fibrosis. Using a mock cataract surgery model, we discovered a unique subpopulation of polyploid mesenchymal progenitors nestled in small niches among lens epithelial cells that expressed the surface antigen G8 and mRNA for the myogenic transcription factor MyoD. These cells rapidly responded to wounding of the lens epithelium with population expansion, acquisition of a mesenchymal phenotype, and migration to the wound edges where they regulate the wound response of the epithelium. These mesenchymal cells also were a principal source of myofibroblasts that emerged following lens injury and were responsible for fibrotic disease of the lens that occurs following cataract surgery. These studies provide insight into the mechanisms of wound-healing and fibrosis.

WE-B-202-01: IAEA Study of Cataract in Staff Working in Catheterization Laboratories

Staff working in catheterization laboratories, predominantly interventional cardiologists and nurses, are potentially exposed to relatively high levels of ionizing radiation and may be at risk of developing cataracts after several years of work if radiation protection rules are not followed. A number of studies in other radiation exposed populations, including astronauts, atomic bomb survivors, X-ray technologists and those exposed after the Chernobyl nuclear accident, have indicated an increased risk of radiation associated lenticular changes after low-dose exposures, raising concerns regarding interventional cardiology professionals. Recent studies indicate that the threshold for cataract development is lower than was previously estimated and that radiation cataractogenesis may in fact be more accurately described by a linear, no-threshold model and may thus need to be classified as stochastic effect. The higher workload that is typical now in many cath labs, a lack of training in radiation protection and non-availability or non-use of radiation protection devices can result in doses to the eye lens that are high enough to cause lens injuries. International Atomic Energy Agency (IAEA) had launched a project to test the eyes of interventional cardiologists and support staff. The prospective testing was associated with a retrospective dose assessment for the lens of the eye. The eye testing exercises have been done in 20008–2009 at Bogota, Columbia; Montevideo, Uruguay; Kuala Lumpur, Malaysia; Varna and Sofia in Bulgaria. The talk will review the basic information about radiation catactogenesis and results of recent studies that indicate the need for change. It will present the summary of results of yet to be published studies on interventional cardiologists and nurses that do indicate increased prevalence of dots that represent lens injuries which may lead to cataract after many years. Learning Objectives: 1. To understand the basic information about radiation cataractogenesis 2. To understand the studies that have been conducted in the last 15 years that show that cataract is seen at doses lower than the currently believed threshold 3. To become aware about the likely changes in current recommendation that may be brought up by international bodies such as ICRP.

Histological changes in human cornea after cross‐linking with riboflavin and ultraviolet A

Editor, Cross-linking treatment of progressive keratoconus (CXL) using the photosensitizer riboflavin and ultraviolet (UV) A was introduced by Wollensak in 2003 and is becoming increasingly popular (Wollensak et al. 2003a). A long-term effect could be demonstrated recently (Wollensak & Iomdina 2008). Extensive studies have been performed in vitro and in animals to evaluate the potential cytotoxicity increasing the safety of the new treatment modality (Wollensak et al. 2003b, 2004; Wollensak 2006). However, no human microscopic specimens have been studied so far. Recently, I had the opportunity to examine histologically the eye of a patient whose cornea had been cross-linked 24 hr before enucleation. The 23-year-old man with a blind painful left eye (caused by status post-severe perforating sclera and lens injury in 1992 and subsequent unsuccessful operations for visual restoration including vitrectomy, encircling band and silicone oil) had a visual acuity of 20/20 in his healthy right eye. With the patient’s consent, a standard cross-linking treatment was performed in the left eye one day before the scheduled enucleation. As described previously, the central 8 mm of the epithelium was removed and the cornea soaked with the 0.1% riboflavin solution for 20 min. Irradiation was performed for 30 min using a UVA double diode (3 mW/cm2) at a distance of 1 cm. Antibiotic ointment was administered after the cross-linking procedure and the eye was enucleated 24 hr later. The retrieved eye was fixed in neutral buffered 4% formalin. Paraffin sections (4 μm thin) were stained with haematoxylin and eosin. On light microscopy, absence of the epithelium in the debrided central cornea was noted. Bowman’s layer was unremarkable. There was complete loss of keratocytes down to a depth of 250–280 μm with normal keratocyte density beneath. Descemet’s membrane and the endothelial cells were complete and intact (Fig. 1). There were no inflammatory cells and only minimal oedema. Apart from the corneal findings, the lens was partially calcified and the retina atrophic with silicone oil inclusions and a funnel-shaped retinal detachment. Photomicrograph of cross-linked human cornea 24 hr after cross-linking. Note the absence of epithelium, loss of keratocytes down to 250 μm (zone A), intact keratocytes in posterior stroma (zone B) forming a ‘safety zone’, intact endothelium and the absence of inflammatory cells (haematoxylin and eosin stain, × 200). Concurrent findings have been reported after standard CXL applying 3 mW/cm2 of UVA for 30 min: keratocyte damage has been observed down to 300 μm using in vivo confocal microscopy (Mazzotta et al. 2007) like in the animal experiments. Accordingly, a treatment effect as evaluated by hydration studies (Wollensak et al. 2007) and slit-lamp biomicroscopy (Seiler & Hafezi 2006) is also noted only in the anterior stroma down to 250–300 μm. Interestingly, the cytotoxic threshold for the endothelium is only 0.36 mW/cm2 (Wollensak et al. 2003b) compared to 0.5 mW/cm2 (Wollensak et al. 2004) for keratocytes. There is a relatively large safety gap towards the endothelium with still-intact keratocytes: otherwise, the endothelium with its lower cytotoxic threshold would be destroyed despite keratocyte survival directly anterior to the endothelium. In conclusion, the present article confirms earlier findings in animals and demonstrates a high degree of safety for the endothelium in standard CXL as long as a stromal thickness of at least 400 μm is present in the irradiated target area of the cornea.