Iris Pigment Research Articles

Apoptosis inhibitor of macrophages/CD5L enhances phagocytosis in the trabecular meshwork cells and regulates ocular hypertension.

The trabecular meshwork (TM) cells of the eye are important for controlling intraocular pressure (IOP) and regulating outflow resistance in the aqueous humor. TM cells can remove particles and cellular debris by phagocytosis, decreasing both outflow resistance and IOP. However, the underlying mechanisms remain unclear. Here, we investigate whether apoptosis inhibitor of macrophages (AIM), which mediates the removal of dead cells and debris in renal tubular epithelial cells, regulates the phagocytic capacity of TM cells. In vitro experiments revealed that CD36, the main receptor for AIM, colocalized with AIM in human TM cells; additionally, phagocytosis was stimulated when AIM was provided. Furthermore, in a mouse model with transient IOP elevation induced by laser iridotomy (LI), removal of accumulated iris pigment epithelial cells or debris in the TM and recovery of IOP to baseline levels were delayed in AIM-/- mice, compared with control mice. However, treatment with AIM eyedrops rescued AIM-/- mice from the elevated IOP after LI. Since AIM is a protein known to inhibit macrophage apoptosis, we additionally verified its involvement in macrophage removal of cellular debris and IOP. There were no statistically significant differences in the number of macrophagesbetween control mice and AIM-/- mice in the TM. Additionally, we confirmed the rescue effect of the rAIM eyedrops after macrophageshad been removed by clodronate liposomes. Therefore, AIM plays an important role in regulating the phagocytic capacity of TM cells, thereby affecting outflow resistance. Our results suggest that drugs targeting the phagocytic capacity of TM cells via the AIM-CD36 pathway may be used to treat glaucoma.

Ebola Virus Tropism in Ex Vivo Cynomolgus Macaque Ocular Tissues.

Ocular complications of Ebola virus disease are well-documented and long-term sequelae in survivors are common and lead to considerable morbidity. However, little is currently known regarding EBOV's tropism and replication kinetics within the eye. To date, limited studies have utilized in vitro infections of ocular cell lines and analyses of archived pathology samples to investigate these issues. Here, we employed ex vivo cultures of cynomolgus macaque eyes to determine the tropism of EBOV in 7 different ocular tissues: cornea, anterior sclera with bulbar conjunctiva, ciliary body, iris, lens, neural retina, and retina pigment epithelium. We report that, except for neural retina, all tissues supported EBOV replication. Retina pigment epithelium produced the fastest growth and highest viral RNA loads, although the differences were not statistically significant. Immunohistochemical staining confirmed and further characterized infection. This study demonstrates that EBOV has a broad tropism within the eye.

Murine cytomegalovirus localization and uveitic cell infiltration might both contribute to trabecular meshwork impairment in Posner-Schlossman syndrome: Evidence from an open-angle rat model

As a special type of glaucoma, Posner-Schlossman syndrome (PSS) is characterized by elevated intraocular pressure (IOP) and anterior uveitis. Cytomegalovirus (CMV) anterior chamber infection has now been considered the leading cause of PSS. We used murine CMV (MCMV) intracameral injection to establish a rat model manifested in IOP elevation and mild anterior uveitis, much like PSS; viral localization and gene expression at various time points and inflammatory cell infiltration derived from innate and adaptive immunity were investigated, as well as pathogenetic changes of the trabecular meshwork (TM). The IOP and uveitic manifestations peaked at 24 h post-infection (p.i.) and returned to normal after 96 h; the iridocorneal angle remained open consistently. At 24 h p.i., leucocytes gathered at the chamber angle. Maximum transcription of MCMV immediate early 1 (IE1) was reached at 24 h in the cornea and 48 h in the iris and ciliary body. MCMV localized in aqueous humor outflow facilities and the iris from 24 h to 28 d p.i. and was detected by in situ hybridization, though it did not transcribe after 7 d p.i. TM and iris pigment epithelial cells harboring viral inclusion bodies and autophagosomes were present at 28 d p.i. These findings shed light on how and where innate and adaptive immunity reacted after MCMV was found and transcribed in a highly ordered cascade, as well as pathogenetic changes in TM as a result of virus and uveitis behaviors.

Selective Laser Trabeculoplasty (SLT) for IOP Control in a Patient with Bilateral Acute Iris Transillumination (BAIT)

ABSTRACT Introduction Bilateral acute iris transillumination (BAIT) is a clinical condition characterized by acute bilateral loss of iris pigment epithelium and iris transillumination. Because of the similar presentation, it is commonly confused with anterior uveitis, making it an important differential diagnosis for this condition. Case description We report the case of a 60-year-old male patient who presented all the characteristics of BAIT after undergoing systemic treatment with moxifloxacin and that had the intraocular pressure (IOP) successfully controlled with selective laser trabeculoplasty (SLT). Conclusion SLT might be an effective therapeutic option and should be considered for the control of IOP in BAIT.

Characterizing the lens regeneration process in Pleurodeles waltl

BackgroundAging and regeneration are heavily linked processes. While it is generally accepted that regenerative capacity declines with age, some vertebrates, such as newts, can bypass the deleterious effects of aging and successfully regenerate a lens throughout their lifetime. ResultsHere, we used Spectral-Domain Optical Coherence Tomography (SD-OCT) to monitor the lens regeneration process of larvae, juvenile, and adult newts. While all three life stages were able to regenerate a lens through transdifferentiation of the dorsal iris pigment epithelial cells (iPECs), an age-related change in the kinetics of the regeneration process was observed. Consistent with these findings, iPECs from older animals exhibited a delay in cell cycle re-entry. Furthermore, it was observed that clearance of the extracellular matrix (ECM) was delayed in older organisms. ConclusionsCollectively, our results suggest that although lens regeneration capacity does not decline throughout the lifespan of newts, the intrinsic and extrinsic cellular changes associated with aging alter the kinetics of this process. By understanding how these changes affect lens regeneration in newts, we can gain important insights for restoring the age-related regeneration decline observed in most vertebrates.

A comparative study between a transscleral sustained-release device and eyedrops on intraocular distribution of carteolol hydrochloride

The objectives of this study were to develop a sustained-release device for carteolol hydrochloride (CH) and investigate any potential difference in the intraocular distribution of this agent between the transscleral administration of the device and treatment with eyedrops. The device was formulated with photocurable resin, poly (ethyleneglycol) dimethacrylate, to fit within the curve of the rabbit eyeball. In vitro study showed that CH was released in a sustained-release manner for 2 weeks. The concentration of CH in the retina, choroid/retinal pigment epithelium, sclera, iris, and aqueous humor was determined by high-performance liquid chromatography. Transscleral administration was able to deliver CH to the posterior segment (i.e., retina and choroid/retinal pigment epithelium) rather than the anterior segment (i.e., aqueous humor), while eyedrops delivered CH only to the anterior segment. Transscleral administration could deliver CH to aqueous humor at half the concentration versus treatment with eyedrops and reduced intraocular pressure (IOP) at 1 day after implantation; however, the IOP-lowering effect was not sustained thereafter. In conclusion, transscleral drug delivery may be a useful method for the reduction of IOP. Notably, the aqueous concentration must be equal to that delivered by the eyedrops, and this approach might be preferable for drug delivery to the posterior segment of the eye.

Argon laser trabeculoplasty for congenital ectropion uveae: Case report and review of the literature.

A 18-year-old woman with unilateral glaucoma secondary to congenital ectropion uveae (CEU) in the right eye, without other systemic and ocular associations. Intraocular pressure (IOP) was uncontrolled under topical therapy. The visual field (VF) was within normal limits; retinal nerve fiber layer (RNFL) thickness, as evaluated by Optical Coherence Tomography (OCT), was reduced. The patient refused surgical intervention. After evaluation of the iridocorneal angle, ALT was performed as follows: 95 spots were applied for the 270 ° of visible trabecular meshwork using a laser beam diameter of 50 μm, an exposure time of 0.1 s and a power of 750 mw). Mean IOP in the right eye, as evaluated by diurnal tonometric curve, was 10 mmHg, 16 mmHg and 20 mmHg respectively one month, four months and eight months after ALT, with no additional topical therapy, and 18 mmHg twelve months after ALT with topical therapy. CEU is a rare, non-progressive anomaly characterized by the proliferation of iris pigment epithelium on anterior surface of iris; glaucoma, in this disorder, is often poorly controlled with medical therapy alone. In a phase of initial glaucomatous damage and with a not particularly high IOP, as in this case, ALT could be an alternative therapeutic option at least in the short-term, when surgery is not feasible immediately. In fact, given its limited effectiveness over time, ALT can be used as a temporary control measure of IOP, pending surgery to become feasible.

SOX2-positive retinal stem cells are identified in adult human pars plicata by single-cell transcriptomic analyses.

Stem cell therapy is a promising strategy to rescue visual impairment caused by retinal degeneration. Previous studies have proposed controversial theories about whether in situ retinal stem cells (RSCs) are present in adult human eye tissue. Single-cell RNA sequencing (scRNA-seq) has emerged as one of the most powerful tools to reveal the heterogeneity of tissue cells. By using scRNA-seq, we explored the cell heterogeneity of different subregions of adult human eyes, including pars plicata, pars plana, retinal pigment epithelium (RPE), iris, and neural retina (NR). We identified one subpopulation expressing SRY-box transcription factor 2 (SOX2) as RSCs, which were present in the pars plicata of the adult human eye. Further analysis showed the identified subpopulation of RSCs expressed specific markers aquaporin 1 (AQP1) and tetraspanin 12 (TSPAN12). We, therefore, isolated this subpopulation using these two markers by flow sorting and found that the isolated RSCs could proliferate and differentiate into some retinal cell types, including photoreceptors, neurons, RPE cells, microglia, astrocytes, horizontal cells, bipolar cells, and ganglion cells; whereas, AQP1- TSPAN12- cells did not have this differentiation potential. In conclusion, our results showed that SOX2-positive RSCs are present in the pars plicata and may be valuable for treating human retinal diseases due to their proliferation and differentiation potential.

Iris Color Matters-A Contractility Analysis With Dynamic Volume-Rendered Optical Coherence Tomography Pupillometry.

To analyze natural variability in pupillary contractility with dynamic volume-rendered optical coherence tomography (OCT) pupillometry regarding iris color, age, and sex in healthy Caucasian participants. The intrapupillary spaces (IPSs) derived from anterior segment swept-source OCT of 71 healthy eyes were retrospectively analyzed. Baseline scotopic and photopic volumes and the functional parameters of pupillary ejection fraction (PEF), three-dimensional (3D) contractility, and relative light response (RLR) were measured on the swept-source OCT volumes. The effect on these parameters of iris color (brown, green, and blue), age, and sex was assessed. More pigmented irises were more contractile than less pigmented irises. Iris color significantly affected scotopic baseline IPSs (brown, 10.39 ± 4.86 mm3; green, 9.68 ± 3.31 mm3; blue, 6.75 ± 4.27 mm3; P = 0.018), PEF (brown, 90.8% ± 2.7%; green, 89.1% ± 2.5%; blue, 85.0% ± 9.3%; P = 0.010), 3D contractility (brown, 9.52 ± 4.59 mm3; green, 8.66 ± 3.07 mm3; blue, 6.44 ± 4.87 mm3; P = 0.016), and RLR (brown, 11.90 ± 4.03; green, 9.75 ± 2.73; blue, 8.52 ± 3.88; P = 0.026). Absolute scotopic volume (P = 0.022) and 3D contractility (P = 0.024) decreased with age. Sex showed no correlations. The natural variability of pupillary contractility can be analyzed with dynamic OCT pupillometry. Iris color and age can impact pupillary response with this method. Iris contractility parameters can be measured using a commercially available OCT system, allowing for quantification of the aqueous humor volume inside the pupil.

GMP-Grade Manufacturing and Quality Control of a Non-Virally Engineered Advanced Therapy Medicinal Product for Personalized Treatment of Age-Related Macular Degeneration.

The introduction of new therapeutics requires validation of Good Manufacturing Practice (GMP)-grade manufacturing including suitable quality controls. This is challenging for Advanced Therapy Medicinal Products (ATMP) with personalized batches. We have developed a person-alized, cell-based gene therapy to treat age-related macular degeneration and established a vali-dation strategy of the GMP-grade manufacture for the ATMP; manufacturing and quality control were challenging due to a low cell number, batch-to-batch variability and short production duration. Instead of patient iris pigment epithelial cells, human donor tissue was used to produce the transfected cell product ("tIPE"). We implemented an extended validation of 104 tIPE productions. Procedure, operators and devices have been validated and qualified by determining cell number, viability, extracellular DNA, sterility, duration, temperature and volume. Transfected autologous cells were transplanted to rabbits verifying feasibility of the treatment. A container has been engineered to ensure a safe transport from the production to the surgery site. Criteria for successful validation and qualification were based on tIPE's Critical Quality Attributes and Process Parameters, its manufacture and release criteria. The validated process and qualified operators are essential to bring the ATMP into clinic and offer a general strategy for the transfer to other manufacture centers and personalized ATMPs.

Bilateral Acute Depigmentation of Iris (BADI) and Bilateral Acute Iris Transillumination (BAIT)-An Update.

Bilateral acute depigmentation of the iris (BADI) and bilateral acute iris transillumination (BAIT) are relatively new clinical entities characterized by acute pigment dispersion from the iris stroma or iris pigment epithelium, respectively. While BADI presents with diffuse or geographic areas of iris stromal depigmentation without transillumination, BAIT cases typically develop diffuse iris transillumination and mydriatic atonic pupils. Prolonged pigment dispersion and ocular hypertension are more common in BAIT. Although the exact etiopathogenesis is still unknown, moxifloxacin toxicity appears to be a probable/likely cause. The underlying cause of BADI or BAIT in patients who were not exposed to fluoroquinolone antibiotics remains unexplained. Systemic viral infections, including coronavirus disease 2019, may be the triggering event in several cases.

Role of Monocytes/Macrophages in the Etiology of Bullous Keratopathy After Argon Laser Iridotomy.

PurposeThe etiologic mechanisms of bullous keratopathy (BK) after argon laser iridotomy (ALI) are still unknown. Therefore, we investigated potential mechanisms on BK after ALI.MethodsCorneal endothelial surface obtained in penetrating keratoplasty for BK after ALI was observed and analyzed immunohistochemically. We investigated how various leukocytes react to cultured human corneal endothelial cells in an inflamed condition and monocytes/macrophages respond to the iris treated by an argon and YAG laser or pigmented and nonpigmented iris treated by an argon laser.ResultsWe detected infiltration of CD68- and CD11b-positive monocytes/macrophages in the posterior surface of trephined corneas obtained during penetrating keratoplasty for BK after ALI in three of the seven eyes with ALI. In vitro, monocytes/macrophages, but not T cells, B cells, neutrophils, or pan-leukocytes, removed many cultured human corneal endothelial cells in the medium stimulated with proinflammatory cytokines. Human pigmented iris tissues treated by the argon laser, but not those treated by the YAG laser, attracted many monocytes/macrophages and formed large, round colonies. Human monocytes/macrophages formed large colonies on the argon laser–treated pigmented iris from C3H mice but not nonpigmented iris from albino BALB/c mice.ConclusionsOur results suggest that monocytes/macrophages, argon laser, and pigmented iris are all involved in the pathogenesis of BK after LI.Translational RelevanceEtiology in BK after ALI has not been clear, but our findings based on clinical and experimental findings give a critical clue to explain possible mechanisms on BK after ALI.

Clinical Outcome After Nd: Yag Laser Iridotomy In Patients With Primary Angle Closure Glaucoma: A Hospital Based Study

Purpose: To find out the clinical outcome of Nd: YAG Laser iridotomy in primary angle closure glaucoma (PACG) Study Design: Experimental case series Place and Duration of Study: Prevention of Blindness Eye Hospital Karachi, from January 2021 to June 2021. Methods: Patients of 30 to 60 years of age, either gender and diagnosed with primary angle closure glaucoma were included. After taking informed consent, complete examination including pre and post laser intra ocular pressures (IOP) was performed. Follow up was at 2 hours, 1 day and 1week. Data was collected and analyzed using SPSS version 22. Effect modifiers like age, gender, pre-laser lOP were controlled through stratification. Post stratification Chi square test was applied for complications (raised IOP, iritis, hyphema, corneal damage, lens opacity and posterior synechie) and efficacy. P ≤ 0.05 was considered significant. Results: Mean age of the patients was 44.48±7.28. Stratification of age and gender with efficacy of LPI and early complications showed that there was no effect of age and gender on the results of LPI (p>0.05). Mean pre laser IOP was 18.56±5.28 and post laser IOP was 15.28±4.62. Lens opacity was found in 10 (5.15%), followed by hyphema in 9(4.63%), corneal damage 8 (4.12%), posterior synechie 5 (2.57%), iritis 7(3.60%), raised IOP in 6 (3.069%) patients. Conclusion: It is to be concluded that Laser iridotomy is an effective treatment for PACG even in thicker and more heavily pigmented irides with few reversible side effects.

Bilateral Multiple Primary Cysts of the Iris Pigment Epithelium Occluding Pupil.

Bilateral Multiple Primary Cysts of the Iris Pigment Epithelium Occluding Pupil.

Pigmented floating vitreous cyst

A 6-year-old male reported seeing a floating body in his left eye for a few days. There was no history of ocular trauma or surgery. His visual acuity was 20/20 OD and 20/40 OS, with normal intraocular pressure and a quiet anterior segment. Slit-lamp microscopy revealed a floating, mobile, pigmented mass in the vitreous cavity (Fig. 1A; Supplementary Video 1, available online). Anterior-segment optical coherence tomography revealed a mobile circular cystic mass with hyperechoic thin walls (Fig. 1B). Brain computed tomography and experimental tests for parasitic infection were negative. A diagnosis of iris pigment epithelium cyst was made. The cyst was monitored and remained stable at the 3-month follow-up.

Structure of iris neoplasms in children and adolescents

AIM: To describe clinical cases of iris neoplasms in children and adolescents.
 MATERIAL AND METHODS: The study was based on retrospective and prospective analyses of children and adolescents with iris neoplasia from January 2018 to April 2022. During this period, 44 children with suspected iris neoplasia, including 20 boys and 24 girls, applied to the outpatient department; their ages ranged from 6 months to 17 years (9.15 years). The diagnosis was based on a comprehensive examination of patients including clinical and instrumental methods. Biomicroscopy, ultrasound investigation including ultrasound biomicroscopy, and when necessary, optical coherence tomography of the anterior eye region were performed. When it was impossible to establish the diagnosis due to the childs age, the examination was performed under general anesthesia in the ocular oncology and radiology department.
 RESULTS: Of the 44 iris lesions, nevus was found in 32 (72.7%) patients, iris melanosis in 3 (6.8%), cysts in 5 (11.3%), heterochromia in 1 (2.3%), floccula in 1 (2.3%), hamartroma in 1 (2,3%), and melanocytoma in1 (2,3%). The majority of the patients with these lesions are observed in the outpatient department. From January 2018 to April 2022, six children with iris lesions were examined in the department of ophthalmo-oncology and radiology under general anesthesia; accordingly, two children received dynamic observation, two underwent iridectomy, and two others underwent YAG-laser cystotomy and cystodestruction. Two iridectomies were also performed among adolescents. Histological diagnosis was verified in four patients after iridectomy: iris stromal cyst, iris pigment epithelium cyst, melanocytoma, and iris spindle cell nevi were detected.
 CONCLUSION: According to the observation data, iris nevi were most common (72.7%), followed by cysts (11.3%) and melanosis (6.8%) of the iris. Heterochromia, floccules, and hamartomas, and melanocytoma of the iris had equal frequency (2.3%).

Determining vertical fusion values from digital photographs of healthy eyes.

To determine the mean difference of vertical corneal light reflex (VCLR) among healthy eyes via digital photography. Retrospective study. The study enrolled 155, healthy eyes participants, 71 males and 84 females with a mean age of 14.7years (range 12-19years). The participants received complete eye examinations and 2 digital photographs were taken, with the flash on, while participants fixated their eyes on a near and a distant target. Two hundred and eighty qualified photographs were analyzed by Photo-Hirschberg testing using computer software. The vertical corneal light reflex ratio (VCLRR) was calculated as the distance of the corneal light reflex (CLR) to the inferior limbus or to the pupillary border divided by the horizontal corneal diameter, defined as VCLRR1 or VCLRR2. VCLRR was analyzed using Spearman's correlation. The mean ± SD of horizontal corneal diameter in near and distance photographs was 11.47 ± 0.62 and 11.37 ± 0.58mm, respectively. For correlation analysis, at 1m fixation and 6m fixation, the number of participants within an acceptable range of vertical fusion were 94.6% and 100% of participants. The 95th percentiles (estimated as the mean ± 1.64SD) in VCLRR1 between the two eyes at near and at distance fixation were 0.0316 and 0.0272, respectively; whereas the corresponding values for VCLRR2 were 0.0309 and 0.0240, respectively. The normal range of the vertical corneal light reflex ratio suggests that the Photo-Hirschberg test could be used for screening vertical strabismus cases depending on iris pigment.

The mounted alloimmunity of the iris-ciliary body devotes a hotbed of immune cells for corneal transplantation rejection

Graft rejection is still the major obstacle causing corneal transplantation failure. However, the underlying pathogenesis remains largely unclear. The iris-ciliary body (I–C) is enriched with blood vessels and various immune cell populations, presumably predisposed to be involved in corneal transplantation rejection. After penetrating keratoplasty, compared to the normal (Nor) and syngeneic (Syn) groups, I–C tissues in the allogeneic (Allo) group displayed stronger alloimmune responses, with more infiltrations of CD45+ inflammatory cells and CD3+ lymphocytes, increased transcriptional levels of pro-inflammatory cytokines, and elevated NF-κB activity. This histopathology was similar to the pathological alterations of corneal allografts. Angiography analysis revealed the abnormal vasculature in the iris during allograft rejection, characterized by vasodilatation, increased vessel density, and vascular permeability. While, immunofluorescence staining showed the intact tight junction of the posterior iris epithelium. In vitro, human microvascular endothelial cells (HMECs) stimulated by tumor necrosis factor-α (TNF-α) showed an increased Evans blue (EB)-albumin leakage, with lower expression of zonula occludens-1 (ZO-1) and Occludin. The increased EB-albumin leakage, up-regulated NF-κB activity, and reduced expression of ZO-1 and Occludin could be partially reversed after cyclosporine A (CsA) administration. In contrast, the barrier function in primary mouse iris pigment epithelial cells (IPEs) after TNF-α treatment remained largely unchanged. These findings revealed the vigorous alloimmunity in I–C tissues, characterized with impaired vascularization but intact posterior epithelial barrier in the iris, which allowed proteins and immune cells to be exudated from the front surface of I–C tissues, and facilitated immune reaction in the anterior chamber, thereby contributing to aggravated corneal transplantation rejection.

Iris Heterochromia and Choroidal Hypopigmentation in Waardenburg Syndrome

A 10-year-old Black boy was referred for possible retinal hemorrhages. His visual acuity was 20/20 in both eyes. Examination revealed complete iris heterochromia, with one blue iris and one brown iris (Fig A). Fundus examination demonstrated diffuse areas of choroidal hypopigmentation (Fig B-C), notably also in the eye with normal iris pigment. OCT showed a loss of choroidal reflectivity in areas of hypopigmentation (Fig D). The patient did not have a white forelock or hearing loss, but had facial features of telecanthus and a wide nasal root, consistent with a diagnosis of Waardenburg syndrome (Magnified version of Fig A-D is available online at www.aaojournal.org).

Pigmented Free-Floating Iris Cyst in the Anterior Chamber

A 45-year-old man presented with a free-floating cyst in the anterior chamber of his left eye (Fig A-B). Medical history revealed a blunt trauma by firework to the left eye 10 years prior. Anterior-segment OCT scan revealed a cyst in the anterior chamber with hyperreflective walls and clear hyporeflective lumen (Fig C-D). The optical density is comparable with the anterior chamber fluid. The cyst was examined by a pathologist, which resulted in discovery of an iris cyst derived from iris pigment epithelium (hematoxylin and eosin staining) (Fig E).