Posterior Bowing Of Iris Research Articles

Ocular morphologic traits in the American Cocker Spaniel may confer primary angle closure glaucoma susceptibility

Acute primary angle closure glaucoma is a potentially blinding ophthalmic emergency requiring prompt treatment to lower the elevated intraocular pressure in humans and dogs. The PACG in most of canine breeds is epidemiologically similar to humans with older and female patients overrepresented with the condition. The American Cocker Spaniel (ACS) is among the most common breeds observed with PACG development in dogs. This study initially sought to identify genetic risk factors to explain the high prevalence of PACG in ACSs by using a case–control breed-matched genome-wide association study. However, the GWAS failed to identify candidate loci associated with PACG in this breed. This study then assessed intrinsic ocular morphologic traits that may relate to PACG susceptibility in this breed. Normal ACSs without glaucoma have a crowded anterior ocular segment and narrow iridocorneal angle and ciliary cleft, which is consistent with anatomical risk factors identified in humans. The ACSs showed unique features consisting of posterior bowing of iris and longer iridolenticular contact, which mirrors reverse pupillary block and pigment dispersion syndrome in humans. The ACS could hold potential to serve as an animal model of naturally occurring PACG in humans.

Biometric and Structural Ocular Manifestations of Anterior Megalophthalmos.

ObjectiveThe aim of this study was to examine the biometric ocular manifestations and structural ocular features of anterior megalophthalmos (AM).MethodsFifteen patients with AM (30 eyes) from the Eye & ENT Hospital of Fudan University were included. The age-matched control group consisted of 30 participants (30 eyes) who underwent Pentacam HR and IOLMaster 700 measurements for one normal eye. Data on demographics, biometric manifestations, and genotypes were carefully compared.ResultsA total of 15 patients with AM and 30 control patients were enrolled. There were no differences in age (37.27 ± 19.1 vs. 31.43 ± 19.69 years, P = 0.249) between these two groups. AM eyes were characterized by premature cataracts (11/30, 36.67%) and zonular weakness with lens subluxation (22/30, 73.33%) compared with the control group. Notably, 20 of the 30 AM eyes (66.67%) had significant posterior iris bowing, and 16 of the 30 AM eyes (53.33%) showed an enlarged ciliary ring on ultrasound biomicroscopy (UBM). Mean corneal curvature was lower in the AM eyes (42.01 ± 2.06 D vs. 43.14 ± 1.38 D, P = 0.023). There was no significant difference in corneal pachymetry and central endothelial cell count between the AM and control groups. Significant differences were found in terms of the anterior chamber and white-to-white (WTW) among the Pentacam HR and IOLMaster 700 in patients with AM (P < 0.05). The difference was 0.53 ± 0.48 mm and 0.36 ± 0.14 mm, respectively (P < 0.001).ConclusionThe results of this cohort study conclude the biometric and structural ocular manifestations in Chinese cohorts. Posterior iris bowing (66.67%) and lens subluxation (73.33%) are the most characteristic findings in patients with AM with anatomical abnormalities of megalocornea and a deep anterior chamber, although corneal biometric manifestations of AM included flatter cornea and lower total corneal astigmatism. The knowledge of ocular manifestations of AM is important for diagnosis and preparation for the operation in advance to avoid intraoperative and postoperative complications. Significant differences were found in the anterior chamber and WTW values between the Pentacam HR and IOLMaster 700. Thus, we suggest that various examinations should be carefully considered before determining an AM diagnosis.

Physical Factors Affecting Outflow Facility Measurements in Mice.

Mice are commonly used to study conventional outflow physiology. This study examined how physical factors (hydration, temperature, and anterior chamber [AC] deepening) influence ocular perfusion measurements in mice. Outflow facility (C) and pressure-independent outflow (Fu) were assessed by multilevel constant pressure perfusion of enucleated eyes from C57BL/6 mice. To examine the effect of hydration, seven eyes were perfused at room temperature, either immersed to the limbus in saline and covered with wet tissue paper or exposed to room air. Temperature effects were examined in 12 eyes immersed in saline at 20 °C or 35 °C. Anterior chamber deepening was examined in 10 eyes with the cannula tip placed in the anterior versus posterior chamber (PC). Posterior bowing of the iris (AC deepening) was visualized by three-dimensional histology in perfusion-fixed C57BL/6 eyes and by spectral-domain optical coherence tomography in living CD1 mice. Exposure to room air did not significantly affect C, but led to a nonzero Fu that was significantly reduced upon immersion in saline. Increasing temperature from 20 °C to 35 °C increased C by 2.5-fold, more than could be explained by viscosity changes alone (1.4-fold). Perfusion via the AC, but not the PC, led to posterior iris bowing and increased outflow. Insufficient hydration contributes to the appearance of pressure-independent outflow in enucleated mouse eyes. Despite the large lens, AC deepening may artifactually increase outflow in mice. Temperature-dependent metabolic processes appear to influence conventional outflow regulation. Physical factors should be carefully controlled in any outflow studies involving mice.

Pigment dispersion secondary to anterior chamber angle recession

Dear Editor: Irido-zonular and/or -lenticular disruption, mostly due to posterior bowing of the iris, is believed to be the mechanism of primary pigment dispersion syndrome (PDS). Characteristic findings of PDS include Krukenberg spindle, homogenous trabecular meshwork (TM) pigmentation, and spoke-like mid-peripheral iris transillumination defects [1–5]. Primary PDS usually affects bilateral eyes, although the morbidity and manifestations may be asymmetric. Herein, we report an unusual case of monocular pigment dispersion secondary to traumatic anterior chamber angle recession. A 33-year-old male complained of blurred vision and distending pain in his right eye for more than 1 year. He sustained blunt ocular trauma by a wooden stick 10 years prior. He had no family history of either glaucoma or PDS. On admission, his visual acuity was 20/200 OD and 20/20 OS. A Krukenberg spindle was discerned in his right eye (Fig. 1a), along with posterior bowing of the mid-peripheral iris. A Zentmayer ring was visualized on the rear surface of the crystalline lens. Homogenous heavy TM pigmentation and 270o of anterior chamber (AC) angle recession were revealed on gonioscopy (Fig. 1b). Spoke-like iris transillumination defects were not seen. His left eye was unremarkable on both biomicroscopy and gonioscopy, with minimal TM pigmentation and flat iris configuration (Fig. 1c). The vertical cup/disc ratio was 0.9 OD and 0.3 OS. The intraocular pressure (IOP) was 52 OD and 17 OS. Refraction revealed −0.25 diopters in both eyes. Humphrey visual field analysis showed inferior arcuate scotoma in the right eye and normal field in the left. Ultrasound biomicroscopy (UBM) revealed posterior bowing of the iris and irido-zonular and -lenticular contact in the right eye (Fig. 1d), and flat iris in the left. The patient underwent trabeculectomy for pigmentary glaucoma in his right eye, with postoperative IOP in the teens during 6 years of follow-up. The iris became flat, and no more pigment dispersion was discerned after the surgery. Visual field deterioration was not detected with Humphrey visual field analysis postoperatively. The left eye did not show any signs of pigment dispersion or other ocular disorders after 6 years of surveillance. Pigment dispersion may occur after ocular trauma, intraocular lens implantation, iritis, and so on [1, 4, 6]. However, such secondary pigment dispersion differs from primary PDS, in that the former usually does not have Krukenberg spindle and iris transillumination defects. Krukenberg spindle is more likely to be the result of continuous pigment shedding like primary PDS, which is secondary to irido-zonular contact. The typical appearance This manuscript has not been published or submitted for publication elsewhere. We certify that all applicable institutional and governmental regulations concerning the ethical use of human subjects were followed during this research. The authors have full control of the primary data, and they agree to allow Graefe’s Archive for Clinical and Experimental Ophthalmology to review their data if requested.

Posterior Iris Bowing after accomodation—Elucidation of the etiology of pigment dispersion syndrome

Recent advancements in imaging the anterior segment structures using the ultrasound biomicro scope (UBM) have proven the involvement of posterior iris bowing due to reverse pupillary block as the cause of pigment dispersion syndrome. In this report, we examined whether the posterior iris bowing occurs even in normal eyes following accommodation, and whether the degree of iris concavity tends to be greater in myopic eyes than in emmetropic eyes. The subjects were normal eyes with sufficient accommodation power, i.e. 5 myopic eyes with less than-5 diopter reflection, 5 emmetropic eyes within +/- 1 dioptor reflection, respectively. We obtained UBM images of the iris at 4 portions before and after accommodation, and measured the degree of posterior iris bowing. We found that almost all data shift posteriorly after accommodation, and that the iris concavity is more distinct in myopic eyes than in emmetropic eyes both before and after accommodation (before: p = 0.0004, after: p < 0.0001). From these results, we confirmed that iris concavity after accommodation occurs in normal eyes but not enough for iridozonular contact, and that pigment dispersion syndrome results from augmented iris concavity owing to pre-existing factors such as iris flexibility, myopia, and sufficient accommodation power.

Pigment dispersion and recurrent hyphema associated with in-the-bag lens implantation

We present the case of a patient who experienced recurrent episodes of blurry vision and eye pain after uneventful cataract extraction and in-the-bag intraocular lens (IOL) implantation. Examination revealed a microhyphema and signs of pigment dispersion. Iris transillumination was seen overlying areas where the IOL optic was not covered by the anterior capsule. Anterior segment optical coherence tomography confirmed iris indentation by the IOL optic, which was alleviated by performing laser peripheral iridotomy. This case shows that IOLs in the capsular bag can erode the posterior surface of the iris and that an adequately sized capsulorhexis should be performed to ensure anterior capsule coverage. Laser peripheral iridotomy should be considered when significant posterior iris bowing is observed.

Clinical characteristics of pigment dispersion syndrome in Chinese patients

To report clinical findings and characteristics of pigment dispersion syndrome (PDS) in Chinese patients. PDS suspects with any one of the following signs: corneal endothelial pigmentation, iris transillumination defects (ITDs), pigment granule dusting on anterior iris surface, posterior iris bowing, trabecular meshwork (TM) pigmentation, and lenticular or zonular pigmentation were evaluated for PDS at the glaucoma specialty clinic at Beijing Tongren Eye Centre. Diagnosis of PDS required at least two of the following signs: Krukenberg spindle, moderate-to-heavy TM pigmentation (>or=Scheie II) and any degree of lenticular and/or zonular pigmentation. Eighteen patients (12 males and six females) were identified as having PDS during a 1-year period, with mean age of 35.5+/-7.0 years (range, 22-49). All but two eyes from two patients had myopia of -0.5 D or greater, with mean spherical equivalent power of -5.20+/-5.80 D (range, -24.75+/-0.5). The average IOP at initial diagnosis was 33.7+/-10.5 mm Hg (range, 16-56). Fifteen patients (83.3%) were found to have pigmentary glaucoma at their initial diagnosis. All patients showed homogenous increased TM pigmentation as well as lenticular and/or zonular pigmentation. 61.1% of patients (11 of 18) had Krukenberg spindle. None of the patients exhibited spoke-like midperipheral ITDs except for trace-isolated transillumination in both eyes of the two patients. The most common clinical findings in Chinese PDS patients include homogeneous TM pigmentation and pigment granule dusting on lens zonules and/or posterior peripheral lens surface. ITDs are uncommon in Chinese patients with PDS.

Phacoemulsification and LensIris Diaphragm Retropulsion Syndrome

Abstract. Lens-iris diaphragm retropulsion syndrome is mainly caused by a reverse pupillary block as a result of a defect or laxity in the zonular apparatus. It is characterized by a posterior displacement of the lens-iris diaphragm with posterior iris bowing, pupil dilation, and pain. The authors describe a new management technique using an iris hook retractor to lift the iris to relieve the pupillary block. [Ophthalmic Surg Lasers Imaging 2005;36:512-513.]

Management of lens-iris diaphragm retropulsion syndrome during phacoemulsification

Lens–iris diaphragm retropulsion syndrome (LIDRS) occurs more often than recognized during small-incision phacoemulsification. This syndrome requires an infusion of fluid into the anterior chamber and is characterized by posterior displacement of the lens-iris diaphragm, marked deepening of the anterior chamber, posterior iris bowing, pupil dilation, and often significant patient discomfort. Using microendoscopy, we have observed that LIDRS is essentially a reverse pupillary block. We describe a surgical technique to mechanically break the iridocapsular block to restore normal chamber depth, relieve patient discomfort, and allow the surgeon to proceed safely with phacoemulsification.

Clinical signs of the pigment dispersion syndrome in blacks.

The pigment dispersion syndrome (PDS) is considered rare in blacks, and minimal literature exists concerning the condition in this patient population. The diagnosis of PDS in blacks may present unique challenges because some of the typical clinical signs that are present in whites, including iris transillumination defects, posterior iris bowing, and noticeable anterior iris stromal pigment dusting, may not occur as commonly. Diagnosis can be particularly difficult when neither these signs nor significant corneal endothelial pigmentation exists. Although zonular and peripheral lens pigment has been found to be consistently present in whites with PDS, attention has not been given to this as a potentially important diagnostic sign in blacks. From among a primary care population, we identified and studied 7 patients (13 eyes) who exhibited moderate to heavy trabecular meshwork (TM) pigmentation, as well as zonule and/or peripheral lens pigmentation. Patients were identified during routine clinical care provided by one of the authors, as well as from notification by other practitioners. All patients received complete eye examination and other signs of PDS were looked for. Four males and 3 females were identified, their average age being 37 years (range = 15 to 51) at the time of their initial identification. All but one patient was myopic (average approximately -2.50 D spherical equivalent). Iris transillumination defects were present in only one eye of one patient, and no eyes showed overt posterior iris bowing, although the iris contours were usually flat and the anterior chambers appeared relatively deep. Corneal endothelial pigmentation was frequently barely detectable and could not be relied on as a predictor of trabecular meshwork or lenticular pigmentation. Glaucoma, or a suspicion of glaucoma due to increased intraocular pressure (IOP) or cupping, was common among the group. Using heavy TM pigmentation as well as any degree of zonular and/or peripheral lenticular pigmentation as a criteria for the diagnosis of PDS, we calculated the prevalence of PDS among blacks in a nonreferred primary care population (> age 7) to be at least 15 cases per 10,000. More investigation is needed to study the clinical presentation of PDS in blacks because it may be substantially different than in whites. Zonular and peripheral lenticular pigmentation may be a particularly useful diagnostic sign of PDS in blacks, especially in those cases where other traditional signs, including iris transillumination defects, pronounced corneal endothelial pigmentation, posterior iris bowing, and visible anterior iris stromal pigment dusting, are absent. The "classic" variety of PDS may be more common among blacks than previously recognized.

Pigmentary Dispersion Syndrome and Pigmentary Glaucoma: A New Mechanism Concept, A New Treatment, and A New Technique

Reverse pupillary block is introduced as a new cataract-implant complication and as the principle mechanism in pigmentary dispersion syndrome (PDS) and pigmentary glaucoma (PG), causing posterior iris bowing and zonular rubbing. This mechanism was investigated by performing laser iridotomy on six patients. Following surgery, the iris moved forward completely and permanently to the planar position. A new technique, locating the iridotomy by transillumination, reduced the laser energy needed for iridotomy. Laser iridotomy located with transillumination is recommended as the treatment for iris-zonular rubbing in PDS and PG caused by reverse pupillary block.