Persistent hyperplastic primary vitreous

Fetal eye ultrasound: Normal anatomy, abnormal findings, and clinical impact

Until now, ultrasound examination of the fetal eyes has not played an important role in prenatal diagnosis. National and international guidelines are generally confined to documentation of the presence of the orbits and the lenses. However, in recent years, with the advent of high-resolution ultrasound technology and increasing knowledge of prenatal medicine and genetics, careful examination of the fetal eye has enabled the detection of many ocular malformations before birth. This article provides an overview of the anatomy related to the development of the fetal eye and covers the following conditions: hypertelorism, hypotelorism, exophthalmos, microphthalmos, coloboma, cataract, persistent hyperplastic primary vitreous, retinal detachment, dacryocystocele, and septooptic dysplasia, etc. It is designed to illustrate the spectrum of ocular malformations and their appearance on prenatal ultrasound and to discuss their clinical impact and association with various syndromes.

Papillary Traction Due to the Posterior Form of a Bilateral Persistent Fetal Vasculature Mimicking Papilledema

Persistent fetal vasculature (PFV), or persistent hyperplastic primary vitreous (PHPV), is a congenital developmental disorder characterized by a failure of resorption of the hyaloid system. It typically presents unilaterally and has three forms: anterior, posterior, and mixed. In this case report, a seven-year-old patient, without specific personal or family medical history, was referred from the pediatric department for bilateral papilledema. The patient had a best-corrected visual acuity of 20/20 (Logarithmic Measure of Angle of Resolution (LogMAR): 0) in both eyes. Fundus examination of both eyes revealed congested pseudopapilledema with a short, mobile, brownish band extending from the optic disc towards the vitreous cavity. Ocular ultrasound of both eyes showed a fine hyperechoic line pulling on the optic nerve head, and papillary optical coherence tomography (OCT) showed a papillary traction syndrome. The diagnosis of a posterior and bilateral form of persistent fetal vasculature with papillary traction was established.

"Strabismus in children" is not simple - bilateral persistent hyperplasia primary vitreous: a case report

Persistent hyperplastic primary vitreous (PHPV) is a rare congenital developmental ocular disorder caused by incomplete regression of the embryonic hyaloid vasculature; bilateral presentations are even rarer. We report a 6-year-old child with bilateral PHPV who visited our hospital for strabismus, without exhibiting leukocoria, microphthalmia, and systemic diseases. These unique characteristics distinguish our case from other cases of PHPV. It is crucial to increase awareness of congenital eye disease in children and the importance of performing fundus examination with the pupils dilated.

Molecular and Cellular Regulations in the Development of the Choroidal Circulation System

Disorders in the development and regulation of blood vessels are involved in various ocular disorders, such as persistent hyperplastic primary vitreous, familial exudative vitreoretinopathy, and choroidal dystrophy. Thus, the appropriate regulation of vascular development is essential for healthy ocular functions. However, regulation of the developing choroidal circulation system has not been well studied compared with vascular regulation in the vitreous and the retina. The choroid is a vascular-rich and uniquely structured tissue supplying oxygen and nutrients to the retina, and hypoplasia and the degeneration of the choroid are involved in many ocular disorders. Therefore, understanding the developing choroidal circulation system expands our knowledge of ocular development and supports our understanding of ocular disorders. In this review, we examine studies on regulating the developing choroidal circulation system at the cellular and molecular levels and discuss the relevance to human diseases.

Selective Activation of the Wnt-Signaling Pathway as a Novel Therapy for the Treatment of Diabetic Retinopathy and Other Retinal Vascular Diseases

Retinal ischemia, often associated with various disorders such as diabetic retinopathy (DR), retinal vein occlusion, glaucoma, optic neuropathies, stroke, and other retinopathies, is a major cause of visual impairment and blindness worldwide. As proper blood supply to the retina is critical to maintain its high metabolic demand, any impediment to blood flow can lead to a decrease in oxygen supply, resulting in retinal ischemia. In the pathogenesis of DR, including diabetic macular edema (DME), elevated blood glucose leads to blood-retina barrier (BRB) disruptions, vascular leakage, and capillary occlusion and dropouts, causing insufficient delivery of oxygen to the retina, and ultimately resulting in visual impairment. Other potential causes of DR include neuronal dysfunction in the absence of vascular defect, genetic, and environmental factors. The exact disease progression remains unclear and varies from patient to patient. Vascular leakage leading to edema clearly links to visual impairment and remains an important target for therapy. Despite recent advances in the treatment of DME and DR with anti-VEGFs, effective therapies with new mechanisms of action to address current treatment limitations regarding vessel regeneration and reperfusion of ischemic retinal areas are still needed. The Wnt signaling pathway plays a critical role in proper vascular development and maintenance in the retina, and thus provides a novel therapeutic approach for the treatment of diabetic and other retinopathies. In this review, we summarize the potential of this pathway to address treatment gaps with current therapies, its promise as a novel and potentially disease modifying therapy for patients with DR and opportunities in other retinal vascular diseases.

The Prevalence of Cataract in Children

Cataract is the leading cause of childhood blindness in developing countries. Early detection and treatment of childhood cataracts can reduce the burden of blindness in the nation. Often the etiology of pediatric cataract is idiopathic; however, genetics play a role in the development of congenital cataract. According to epidemiologists, one-fourth of cases of congenital cataracts are hereditary. Gene responsible for the development of cataract is identified using gene mapping, which helps to prevent future blindness in the family. Cataracts can also present with systemic disease, microphthalmia, microcornea, and aniridia. The presentation of cataracts varies in individuals, some are symptomatic while others are asymptomatic. Parents after noticing strabismus and leukocoria bring their children to an ophthalmologist. Early diagnosis can restore visual function in cases of congenital cataract. In young babies, the type of cataract is determined using slit-lamp examination and examination under anesthesia in OR. Most cases of pediatric cataracts are accidental findings during routine checkups. On direct ophthalmoscopy, red reflex is not appreciated in cases of cataracts. Advancing technology changes the ophthalmologist's approach to pediatric cataract surgery, improving postoperative refractory function. In children, minor incision surgery was preferred to heal early. An appropriate choice of intraocular lens (IOL) should be made for implantation in a child's eye to avoid postimplanted complications. Inflammation and amblyopia affect the outcome of treatment. Complications of cataract surgery include posterior capsule opacification, glaucoma, inflammation, and uveitis.

An inhibitor of endothelial ETS transcription factors promotes physiologic and therapeutic vessel regression

During the progression of ocular diseases such as retinopathy of prematurity and diabetic retinopathy, overgrowth of retinal blood vessels results in the formation of pathological neovascular tufts that impair vision. Current therapeutic options for treating these diseases include antiangiogenic strategies that can lead to the undesirable inhibition of normal vascular development. Therefore, strategies that eliminate pathological neovascular tufts while sparing normal blood vessels are needed. In this study we exploited the hyaloid vascular network in murine eyes, which naturally undergoes regression after birth, to gain mechanistic insights that could be therapeutically adapted for driving neovessel regression in ocular diseases. We found that endothelial cells of regressing hyaloid vessels underwent down-regulation of two structurally related E-26 transformation-specific (ETS) transcription factors, ETS-related gene (ERG) and Friend leukemia integration 1 (FLI1), prior to apoptosis. Moreover, the small molecule YK-4-279, which inhibits the transcriptional and biological activity of ETS factors, enhanced hyaloid regression in vivo and drove Human Umbilical Vein Endothelial Cells (HUVEC) tube regression and apoptosis in vitro. Importantly, exposure of HUVECs to sheer stress inhibited YK-4-279-induced apoptosis, indicating that low-flow vessels may be uniquely susceptible to YK-4-279-mediated regression. We tested this hypothesis by administering YK-4-279 to mice in an oxygen-induced retinopathy model that generates disorganized and poorly perfused neovascular tufts that mimic human ocular diseases. YK-4-279 treatment significantly reduced neovascular tufts while sparing healthy retinal vessels, thereby demonstrating the therapeutic potential of this inhibitor.

Surgical outcomes of cataract surgery in anterior and combined persistent fetal vasculature using a novel surgical technique: a single center, prospective study

PURPOSE

To study the complications and surgical outcomes of cataract surgery in patients of persistent fetal vasculature (PFV) with cataract.

METHODS

In this prospective study, phacoaspiration with/without intraocular lens implantation (IOL) was done in 20 children (mean age 14.2 months) with unilateral cataract with anterior (n = 6) or combined (n = 14) PFV. The rentrolental vascularized membrane was cauterized and dissected circumferentially, followed by cauterization and resection of the PFV stalk. The outcome measures included fixation preference using the CSM (central, steady, maintained) method and intraoperative and postoperative complications in an 18-month follow-up. The difference in outcomes of anterior and combined PFV, as well as aphakic and pseudophakic eyes, was studied.

RESULTS

CSM fixation was seen in 16 patients after 18 months. The intraocular lens was implanted in 16 eyes and 4 eyes with combined PFV were left aphakic. None of our patients had intraoperative bleeding. Visual axis obscuration was the major complication seen, requiring membranectomy in 8 children. Pupilloplasty was required with membranectomy in one eye. None of our patients developed glaucoma or retinal detachment.

CONCLUSION

Timely surgical intervention and aggressive amblyopia therapy led to good visual results in our study. Poor prognosis was seen in combined PFV, aphakia, and microphthalmia.

Macrophages fine-tune pupil shape during development

Tissue macrophages, which are ubiquitously present innate immune cells, play versatile roles in development and organogenesis. During development, macrophages prune transient or unnecessary synapses in neuronal development, and prune blood vessels in vascular development, facilitating appropriate tissue remodeling. In the present study, we identified that macrophages contributed to the development of pupillary morphology. Csf1^op/op mutant mice, in which ocular macrophages are nearly absent, exhibited abnormal pupillary edges, with abnormal protrusions of excess iris tissue into the pupillary space. Macrophages located near the pupillary edge engulfed pigmented debris, which likely consisted of unnecessary iris protrusions that emerge during smoothening of the pupillary edge. Indeed, pupillary edge macrophages phenotypically possessed some features of M2 macrophages, consistent with robust tissue engulfment and remodeling activities. Interestingly, protruding irises in Csf1^op/op mice were only detected in gaps between regressing blood vessels. Taken together, our findings uncovered a new role for ocular macrophages, demonstrating that this cell population is important for iris pruning during development.

In vivo imaging of the hyaloid vascular regression and retinal and choroidal vascular development in rat eyes using optical coherence tomography angiography

This study investigates the hyaloid vascular regression and its relationship to the retinal and choroidal vascular developments using optical coherence tomography angiography (OCTA). Normal and oxygen-induced retinopathy (OIR) rat eyes at postnatal day 15, 18, 21, and 24 were longitudinally imaged using OCTA. At each day, two consecutive imaging for visualizing the hyaloid vasculature and the retinal and choroidal vasculatures were conducted. The hyaloid vessel volume and the retinal and choroidal vessel densities were measured. The hyaloid vessel volumes gradually decreased during the regression, although the OIR eyes exhibited large vessel volumes at all time points. A spatial relationship between persistent hyaloid vasculature and retardation of underlying retinal vascular development was observed in the OIR eyes. Furthermore, anti-vascular endothelial growth factor (VEGF) was administered intravitreally to additional OIR eyes to observe its effect on the vascular regression and development. The VEGF injection to OIR eyes showed reduced persistent hyaloid vessels in the injected eyes as well as in the non-injected fellow eyes. This study presents longitudinal imaging of intraocular vasculatures in the developing eye and shows the utility of OCTA that can be widely used in studies of vascular development and regression and preclinical evaluation of new anti-angiogenic drugs.

Widefield Fluorescein Angiography in the Fellow Eyes of Patients with Presumed Unilateral Persistent Fetal Vasculature

PURPOSE

To examine the retinal vascular findings on widefield fluorescein angiography (FA) in the fellow eyes of patients with unilateral persistent fetal vasculature (PFV).

DESIGN

Retrospective case series.

PARTICIPANTS

Consecutive patients with unilateral PFV evaluated by a single physician at an academic medical center from February 1, 2011, to November 30, 2018.

METHODS

Clinical and demographic information, including age, gender, race, ethnicity, affected eye, subtype, stalk origin, complications on presentation, length of follow-up, and examination findings, was reviewed using the electronic medical record. Fluorescein angiograms of the affected and fellow eyes were reviewed by 2 authors for characteristic retinal vascular abnormalities. Agreement between the authors' scores was analyzed using Cohen's Kappa.

MAIN OUTCOME MEASURES

Fluorescein angiography abnormalities, including peripheral vessel avascularity, aberrant circumferential vessels, terminal supernumerary branching, regional capillary dropout, terminal bulbing, abnormal choroidal flush, abnormal vessel straightening, and peripheral vessel leakage or dilation.

RESULTS

Inclusion criteria were met by 41 patients. The average age at initial visit was 10.0 months. The average length of follow-up was 36.4 months. Abnormalities on FA were seen in 31 (75.6%) fellow eyes: peripheral vessel avascularity in 27.5 (67.1%), aberrant circumferential vessels in 20 (48.8%), terminal supernumerary branching in 17 (41.5%), regional capillary dropout in 9 (22.0%), terminal bulbing in 6 (14.6%), abnormal choroidal flush in 3.5 (8.5%), and abnormal vessel straightening and peripheral vessel leakage in 2.5 (6.1%). Statistical analysis disclosed an overall observed agreement of 93.4% among the raters (κ = 0.84, P < 0.0001).

CONCLUSIONS

Retinal vascular abnormalities seen in patients with unilateral PFV were present in the majority of fellow eyes. This suggests that unilateral PFV may in fact be a bilateral, asymmetric process, but the clinical significance of these subtle findings is not known.

Evaluation of collagen derived antiangiogenic factors and matrix metalloproteinases in anterior lens epithelial cells of pediatric eyes with persistent fetal vasculature

Purpose:

To measure levels of collagen-derived antiangiogenic factors (arresten, canstatin, tumstatin, endostatin) and matrix metalloproteinases (MMP-2 and MMP-9) in anterior lens epithelial cells (LECs) and anterior capsules of children with cataract and persistent fetal vasculature (PFV) as cases and cataract without PFV as controls.

Methods:

Anterior capsules harboring LECs were collected from pediatric cataract patients with (n = 13) and without PFV (n = 13) during surgery. Samples were immediately subjected to RNA extraction and cDNA preparation. Quantitative real time PCR was performed to determine the mRNA levels of antiangiogenic factors and matrix metalloproteinases. GAPDH (Glyceraldehyde 3-Phosphate Dehydrogenase) and β Actin were used as the housekeeping control. The mRNA levels were expressed as a ratio, using the delta-delta method for comparing the relative expression results between controls and cases. The non-parametric Mann-Whitney U test was applied for statistical evaluation. P values < 0.05 were statistically significant.

Results:

The relative mRNA levels of arresten, canstatin, tumstatin, endostatin, MMP-2 and MMP-9 in cases were 6.20E-03 ± 0.003, 1.49E-01 ± 0.02, 1.70E-01 ± 0.007, 3.20E-03 ± 0.003, 1.11E-03 ± 0.0009 and 3.72E-04 ± 0.0001. The mRNA levels of arresten was 1.6 times lower (P = 0.01) while mRNA levels of MMP-2, tumstatin and canstatin were 4, 2.5, and 2.3 times higher in cases than in controls. No change was observed in mRNA levels of MMP-9 and endostatin (P = 0.82).

Conclusion:

A significant difference in the levels of arresten, canstatin, tumstatin, and MMP-2 was found in LECs with PFV.

Clinical and pathological characterization of persistent fetal vasculature associated with vitreous hemorrhage

Purpose

To provide clinical and pathological features of posterior persistent fetal vasculature (PFV) presenting with vitreous hemorrhage.

Observations

Case 1 was a one-year old male with PFV reaching up to the posterior lens capsule. Case 2 and 3 both had history of blunt trauma. B-scans in cases 2 and 3 revealed vitreous hemorrhage and an intravitreal tissue attached to the optic disc. Pre-operative visual acuity in cases 1, 2 and 3 was undetermined due to age, hand motion and light perception, respectively. During vitrectomy, a fibrotic stalk attached to the optic nerve was removed, which consisted of fibrovascular tissue enveloping pockets of hemorrhage histopathologically. The fibrovascular tissue contained smooth muscle actin (SMA) positive spindle-shaped myofibroblasts in one case and hemosiderin-laden macrophages in another case. Glial fibrillary acidic protein (GFAP) stain was focally positive in two specimens. The proliferation index was low using Ki-67 stain in all cases. Post-operative visual acuity in case 3 remained unchanged, while improved in case 2 from hand motion to 20/70. There was no recurrence of the vitreous hemorrhage.

Conclusion and Importance

Vitreous hemorrhage may occur in cases of PFV with or without history of blunt trauma. Hemorrhage within the persistent fetal vasculature may become organized with reactive process in the hyaloid stalk. The fibrovascular stalk contained astrocytes and myelofibroblasts which contribute to the formation and contractile function of PFV, respectively. The outcomes following vitrectomy seemed to be satisfactory.

Longitudinal OCT and OCTA monitoring reveals accelerated regression of hyaloid vessels in retinal degeneration 10 (rd10) mice

The hyaloid vascular system (HVS) is known to have an important role in eye development. However, physiological mechanisms of HVS regression and their correlation with developmental eye disorders remain unclear due to technical limitations of conventional ending point examination with fixed tissues. Here, we report comparative optical coherence tomography (OCT) and OCT angiography (OCTA) monitoring of HVS regression in wild-type and retinal degeneration 10 (rd10) mice. Longitudinal OCTA monitoring revealed accelerated regression of hyaloid vessels correlated with retinal degeneration in rd10. Quantitative OCT measurement disclosed significant distortions of both retinal thickness and the vitreous chamber in rd10 compared to WT mice. These OCT/OCTA observations confirmed the close relationship between HVS physiology and retinal neurovascular development. The distorted HVS regression might result from retinal hyperoxia or dopamine abnormality due to retinal remodeling in rd10 retina. By providing a noninvasive imaging platform for longitudinal monitoring of HVS regression, further OCT/OCTA study may lead to in-depth understanding of the physiological mechanisms of HVS regression in normal and diseased eyes, which is not only important for advanced study of the nature of the visual system but also may provide insights into the development of better treatment protocols of congenital eye disorders.

A comparative map of macroautophagy and mitophagy in the vertebrate eye

Photoreception is pivotal to our experience and perception of the natural world; hence the eye is of prime importance for most vertebrate animals to sense light. Central to visual health is mitochondrial homeostasis, and the selective autophagic turnover of mitochondria (mitophagy) is predicted to play a key role here. Despite studies that link aberrant mitophagy to ocular dysfunction, little is known about the prevalence of basal mitophagy, or its relationship to general autophagy, in the visual system. In this study, we utilize the mito-QC mouse and a closely related general macroautophagy reporter model to profile basal mitophagy and macroautophagy in the adult and developing eye. We report that ocular macroautophagy is widespread, but surprisingly mitophagy does not always follow the same pattern of occurrence. We observe low levels of mitophagy in the lens and ciliary body, in stark contrast to the high levels of general MAP1LC3-dependent macroautophagy in these regions. We uncover a striking reversal of this process in the adult retina, where mitophagy accounts for a larger degree of the macroautophagy taking place, specifically in the photoreceptor neurons of the outer nuclear layer. We also show the developmental regulation of autophagy in a variety of ocular tissues. In particular, mitophagy in the adult mouse retina is reversed in localization during the latter stages of development. Our work thus defines the landscape of mitochondrial homeostasis in the mammalian eye, and in doing so highlights the selective nature of autophagy in vivo and the specificity of the reporters used. Abbreviations: ATG: autophagy related; GFP: green fluorescent protein; LC3: microtubule associated protein 1 light chain 3; ONH: optic nerve head; ONL: outer nuclear layer; RPE: retinal pigment epithelium.

Peripheral Persistent Fetal Vasculature: A Report of Three Cases

The authors report three cases of persistent fetal vasculature (PFV) presenting with an atypical peripheral fibrovascular stalk. A 5-month-old with congenital exotropia with a vitreous hemorrhage in the right eye underwent vitrectomy, and a mid-peripheral vitreal vascular stalk was visualized within the area of hemorrhage. The second case is of an 8-year-old with two fetal vascular remnants in the right eye: (1) a stalk superotemporally extending from the pars plana to the mid-peripheral retina that was associated with a retinal break and (2) a focal lens opacity. The third case is a 12-year-old with a history of familial exudative vitreoretinopathy and peripapillary choroidal neovascular membrane found to have a peripheral vitreal stalk in the right eye. These cases demonstrate a rare form of PFV with primarily peripheral remnants. [Ophthalmic Surg Lasers Imaging Retina. 2018;49:e83-e88.].

Prenatal Sonographic Abnormal Appearances of the Fetal Hyaloid Artery: From Normal Variants to Pathology

This is a case series on the abnormal sonographic appearance and outcome of the fetal hyaloid artery (HA) detected during between 1987 and 2015 at one medical center. Fifteen cases were detected during fetal anatomy scans, usually performed at 14 to 16 weeks' gestation. Three other cases were diagnosed following referral for a second opinion. In nine fetuses, the HA regressed normally throughout pregnancy. Of them, eight neonates had normal outcomes and one had cataract at the same eye. All nine other cases ended with adverse outcomes. Failure of the HA to regress in the third trimester appears to be an indicator of congenital blindness.

Bim expression in endothelial cells and pericytes is essential for regression of the fetal ocular vasculature

Apoptosis plays a central role in developmental and pathological angiogenesis and vessel regression. Bim is a pro-apoptotic Bcl-2 family member that plays a prominent role in both developmental and pathological ocular vessel regression, and neovascularization. Endothelial cells (EC) and pericytes (PC) each play unique roles during vascular development, maintenance and regression. We recently showed that germline deletion of Bim results in persistent hyaloid vasculature, increased retinal vascular density and prevents retinal vessel regression in response to hyperoxia. To determine whether retinal vascular regression is attributable to Bim expression in EC or PC we generated mice carrying a conditional Bim allele (Bim^Flox/Flox) and VE-cadherin-cre (Bim^EC mice) or Pdgfrb-cre (Bim^PC mice). Bim^EC and Bim^PC mice demonstrated attenuated hyaloid vessel regression and postnatal retinal vascular remodeling. We also observed decreased retinal vascular apoptosis and proliferation. Unlike global Bim -/- mice, mice conditionally lacking Bim in EC or PC underwent hyperoxia-mediated vessel obliteration and subsequent retinal neovascularization during oxygen-induced ischemic retinopathy similar to control littermates. Thus, understanding the cell autonomous role Bim plays in the retinal vascular homeostasis will give us new insight into how to modulate pathological retinal neovascularization and vessel regression to preserve vision.

A case of morning glory syndrome associated with persistent hyperplastic primary vitreous and Peters' anomaly

We report a case of morning glory syndrome (MGS) associated with persistent hyperplastic primary vitreous (PHPV) and Peters’ anomaly. A 2-day-old girl, born at term with a birth weight of 3,350 g was diagnosed with Peters’ anomaly, cataract, microphthalmia, PHPV, and MGS. A right limbal lensectomy and vitrectomy with stalk cauterization was performed 8 days later. No early postoperative complication occurred, the family was discharged with advice on medication, and follow-up examination was scheduled. The case report reveals the coexistence of PHPV, Peters’ anomaly, and MGS, which may suggest a genetic link.

Intraocular sarcoma associated with lens capsule rupture and persistent hyperplastic primary vitreous in a dog

This case report describes the clinical findings and ocular pathology in an adult Golden Retriever diagnosed with an intraocular sarcoma. Nineteen s prior to diagnosis with a lens capsule rupture and intraocular sarcoma, the dog was diagnosed with persistent hyperplastic primary vitreous and uveitis based on clinical signs and the ultrasonographic appearance of the eye. Two years after enucleation, there was no evidence of metastatic spread of the sarcoma. The immunohistochemical characteristics of the tumor as well as the limitations and supportive evidence used in attempting to identify the histogenesis of the tumor are outlined.

Severe hemophilia in a girl infant with mosaic Turner syndrome and persistent hyperplastic primary vitreous

A 6-month-old girl was referred by an ophthalmologist because of postoperative bleeding. She was scheduled for operation because of persistent hyperplastic primary vitreous. Workups were done and prolonged partial thromboplastin time with normal platelet count, normal bleeding time, and prothrombin time were detected. There was negative family history of bleeding tendency in both maternal and paternal family, so at the first step, Factor XI assay was requested which was normal. Then, von Willebrand factor and factor VIII were assayed which was 127% and less than 1%, respectively. Severe factor VIII deficiency was not suspected in a girl unless in siblings of a hemophilic patient who gets married with her carrier cousin. Chromosomal study and genetic testing were requested and mosaic Turner syndrome (45 XO) with ring X (p22, 2q13) along with inversion 22 (hemizygote) was detected. Abdominal and pelvic sonography showed absence of both ovaries with presence of infantile uterus. Maternal genetic study was in favor of carrier of hemophilia (heterozygote inversion 22). To the best of our knowledge, this is the first case of association of Turner syndrome with severe hemophilia A and persistent hyperplastic primary vitreous.

Prenatal Diagnosis of Persistent Hyperplastic Primary Vitreous: Report of 2 Cases and Review of the Literature

Persistent hyperplastic primary vitreous is a spectrum of congenital ocular abnormalities characterized by leukocoria, microphthalmia, cataracts, extensive intravitreal hemorrhage, persistence of the hyaloid artery, glaucoma, and retinal detachment. It might be isolated or associated with congenital syndromes such as trisomy 13, Walker-Warburg syndrome, and Norrie disease. We present 2 cases of persistent hyperplastic primary vitreous diagnosed by prenatal sonography in the early third trimester. Bilateral hyperechoic lenses and retinal nonattachment were detected in the sonographic examination of the first case, whereas irregular echogenic bands between the lenses and posterior walls of the eyes were prominent in the second case. In both of the cases, ocular findings were accompanied by intracranial findings, including severe hydrocephalus, an abnormal gyral pattern, and cerebellar hypoplasia, suggesting the diagnosis of Walker-Warburg syndrome. We also present a review of the literature regarding the prenatal diagnosis of this malformation.

Developmental regression of hyaloid vasculature is triggered by neurons

Vascular development involves not only vascular growth, but also regression of transient or unnecessary vessels. Hyaloid vasculature is the temporary circulatory system in fetal eyes, which spontaneously degenerates when the retinal blood vessels start to grow. Failure of the hyaloid vessels to regress leads to disease in humans, persistent hyperplastic primary vitreous, which causes severe intraocular hemorrhage and impairs visual function. However, the mechanism underlying the endogenous program that mediates spontaneous regression of the hyaloid vessels is not well understood. In this study, we identify a robust switch triggering this program directed by neurons in mice. Marked up-regulation of vascular endothelial growth factor (VEGF) receptor 2 (VEGFR2) occurs in retinal neurons just after birth via distal-multipotent-mesodermal enhancer, a hemangioblast-specific enhancer of VEGFR2. Genetic deletion of neuronal VEGFR2 interrupts this program, resulting in massive hyaloid vessels that persist even during late postnatal days. This abnormality is caused by excessive VEGF proteins in the vitreous cavity as a result of impairment in the neuronal sequestration of VEGF. Collectively, our data indicate that neurons trigger transition from the fetal to the postnatal circulatory systems in the retina.

Dystrophic hyaloid artery remnants and other abnormalities in a buphthalmic eye with retinoblastoma

Partial persistence of the hyaloid artery unaccompanied by hyperplastic primary vitreous has not been previously reported in association with retinoblastoma. We describe an 18-month-old child with such a finding who had a retinoblastoma that was undifferentiated, extensively necrotic, heavily calcified, and completely filled the eyeball. The enucleated globe harbored a nonperfused, fossilized remnant of the hyaloid artery due to DNA/calcium deposition in the vascular wall. This structure inserted into a lenticular, extracapsular, fibrous plaque corresponding to a Mittendorf dot. The tumor had induced a placoid cataractous lens, obliterated the anterior and posterior chambers, caused glaucoma leading to buphthalmos, and extended into the optic nerve and extraocularly to involve the orbit. We conclude that the retinoblastoma arose early in ocular morphogenesis, at around 4 months gestation, when the programmed involution of the hyaloid artery begins. This process would typically end at 7-8 months gestation, but was aborted by the tumor. The patient died 6 weeks after surgery without receiving further treatment because of the parents' resistance.

Subretinal peripapillary neovascularization associated with persistent fetal vasculature

PURPOSE

The purpose of this study was to report a unique case of persistent fetal vasculature presenting as peripapillary choroidal neovascularization.

METHODS

Ophthalmologic examination, examination under anesthesia, fluorescein angiogram, chart review, review of relevant literature. A 2-year 4-month-old white girl was referred for decreased vision and suspicious retinal findings.

RESULTS

Fundus examination of the right eye demonstrated a peripapillary macular scar with old subretinal hemorrhage, subretinal fluid consistent with peripapillary neovascular net, a persistent fetal vascular stalk, and a central posterior lenticular opacity. Fluorescein angiogram of the right eye showed normal arterial filling in the early phase, normal arteriovenous transit, and late staining with mild leakage.

CONCLUSION

This is a unique case of persistent fetal vasculature presenting with the findings of subretinal exudates and choroidal neovascularization that has not been described before. Although the etiology of the choroidal neovascularization is unclear, we postulate it may be a result of the traction from the persistent fetal vasculature stalk in the peripapillary region. These findings may also be secondary to an optic disk anomaly that was not detected on examination.

pitx2 Deficiency results in abnormal ocular and craniofacial development in zebrafish

Human PITX2 mutations are associated with Axenfeld-Rieger syndrome, an autosomal-dominant developmental disorder that involves ocular anterior segment defects, dental hypoplasia, craniofacial dysmorphism and umbilical abnormalities. Characterization of the PITX2 pathway and identification of the mechanisms underlying the anomalies associated with PITX2 deficiency is important for better understanding of normal development and disease; studies of pitx2 function in animal models can facilitate these analyses. A knockdown of pitx2 in zebrafish was generated using a morpholino that targeted all known alternative transcripts of the pitx2 gene; morphant embryos generated with the pitx2(ex4/5) splicing-blocking oligomer produced abnormal transcripts predicted to encode truncated pitx2 proteins lacking the third (recognition) helix of the DNA-binding homeodomain. The morphological phenotype of pitx2(ex4/5) morphants included small head and eyes, jaw abnormalities and pericardial edema; lethality was observed at ∼6-8-dpf. Cartilage staining revealed a reduction in size and an abnormal shape/position of the elements of the mandibular and hyoid pharyngeal arches; the ceratobranchial arches were also decreased in size. Histological and marker analyses of the misshapen eyes of the pitx2(ex4/5) morphants identified anterior segment dysgenesis and disordered hyaloid vasculature. In summary, we demonstrate that pitx2 is essential for proper eye and craniofacial development in zebrafish and, therefore, that PITX2/pitx2 function is conserved in vertebrates.

Prenatal ultrasonographic diagnosis of persistent hyperplastic primary vitreous

Persistent hyperplastic primary vitreous (PHPV) is a rare developmental malformation of the eye characterized by the presence of a vascular membrane located behind the lens. We report, for the first time in the literature, the identification on ultrasound examination of bilateral cataract and thickened hyaloid artery-lens junction, leading to a diagnosis of bilateral PHPV, in a fetus at 23 weeks' gestation. Histological examination at postmortem confirmed the prenatal diagnosis of bilateral PHPV and cataract. A thorough ultrasound examination of the fetal eye in cases with cataract is recommended.

Unique vascular phenotypes following over-expression of individual VEGFA isoforms from the developing lens

Formation of a correctly organised vasculature and subsequently embryonic survival is critically dependent on the dosage and site-specific expression of VEGF. Murine VEGF exists in three common isoforms (viz. 120, 164 and 188 amino acids) having different organ specific distribution levels. Gene knock-in studies show that expression of any of the individual isoforms of VEGF extends survival until birth, although each is associated with distinct organ-specific abnormalities. Comparison of the effects of VEGF isoform expression is complicated by the general lethality of mis-expression, in addition to cumulative effects of adjacent tissues from the inappropriately patterned vasculature. Here we investigate the effects of over-expression of individual VEGFA isoforms from the lens-specific alphaA-Crystallin promoter and characterise their effects on the vessel morphology of the hyaloid and developing retinal vasculature. Since the hyaloid vasculature is an anatomically distinct, transient vasculature of the eye, comprising 3 cell types (endothelium, pericytes and macrophages) it is possible to more readily interpret the role of individual VEGF-A isoforms in vascular pattern formation in this model. The severity of the vascular phenotype, characterised by a hyperplastic hyaloid at E13.5 and subsequently retinal vascular patterning and ocular defects, is most severe in transgenics over-expressing the more diffusible forms of VEGFA (120 and 164), whereas in VEGFA(188) transgenics the hyaloid vascular defects partially resolve post-natally. The results of this study indicate that individual isoforms of VEGFA induce distinct vascular phenotypes in the eye during embryonic development and that their relative doses provide instructive cues for vascular patterning.

Persistent fetal vasculature and minimal fetal vascular remnants

PURPOSE

To determine the significance of persistent fetal vasculature (PFV) and remnants of fetal vessels in the pathogenesis of pediatric unilateral cataracts.

STUDY DESIGN

Prospective observational case series.

PARTICIPANTS

Thirty-one children with unilateral cataract aged between 2 weeks and 15 years.

METHODS

As part of an ongoing prospective clinical trial concerning treatment and etiology of pediatric cataracts, a subgroup of 31 children with unilateral cataracts was defined. The affected eyes received preoperative and intraoperative biomicroscopic examinations to identify characteristic features of PFV and even minimal fetal vascular remnants (MFVRs) at the level of the posterior lens capsule and anterior hyaloid face. In eyes with MFVRs, 3 different severity degrees were assumed, according to different posterior capsule abnormalities: mild, A; moderate, B; and severe, C. All observations were documented on video and analyzed in relation to age (group I, infants between 0 and 1.5 years; group II, preschool children between 1.6 and 5.9 years; group III, schoolchildren between 6 and 16 years).

MAIN OUTCOME MEASURES

Frequency and morphology of characteristic features of PFV and MFVRs of the posterior lens capsule/anterior hyaloid face, lens clouding, and microphthalmos.

RESULTS

All 31 eyes with unilateral congenital cataracts showed signs of PFV syndrome (100%). Characteristic features of PFV were found in 75% of group I eyes, in 8% of group II eyes, and in 67% of group III eyes. Minimal fetal vascular remnants were found in 25% of group I eyes (severity degree C in all eyes), in 92% of group II eyes (severity degree A in 36.4%, B in 27.2%, and C in 36.4%), and in 33% of group III eyes (severity degree A). Associated microphthalmos was found in all eyes in groups I and III and in 73% of group II, whereas axial lengths were equal in both eyes in 27% of group II children with MFVRs.

CONCLUSIONS

Varying degrees of PFV seem to be a frequent cause of unilateral congenital cataracts. Although characteristic features of PFV occurred mainly in infants, eyes of preschool children were usually very mildly affected, showing MFVRs that were detected only by careful observation during surgery. Abnormalities of the central part of the posterior capsule, such as a translucent opacity or a lenticonic area leading to a spontaneous hole during lens aspiration, may be caused by minimal remnants of PFV.

Leucocoria na infância: diagnóstico diferencial por ultra-sonografia, tomografia computadorizada e ressonância magnética

Leucocoria é um reflexo pupilar anormal à luz incidente, em geral relacionado a uma anormalidade intra-ocular, ocorrendo freqüentemente em crianças. A avaliação da criança com leucocoria deve ser feita principalmente para excluir o diagnóstico de retinoblastoma (causa da metade dos casos). Os autores apresentam os aspectos clínicos e de imagem essenciais ao diagnóstico das causas mais comuns de leucocoria.

X-linked retinoschisis: A clinical and molecular genetic review

X-linked retinoschisis is a leading cause of macular degeneration in male children. It is characterized by a high degree of clinical variability. Clinical features include a stellate foveal retinoschisis, with or without peripheral retinoschisis. The schisis occurs within the inner retina, primarily at the level of the nerve fiber layer. The disease-causing gene, X-linked retinoschisis 1, has recently been identified, and is expressed in photoreceptor and bipolar cells. This gene codes for retinoschisin, a secreted protein containing a discoidin domain which may be involved in cellular adhesion or cell-cell interactions. The identification of this gene allows for improved diagnosis and contributes to the understanding of this condition. Visual prognosis is variable, as X-linked retinoschisis exhibits a high degree of phenotypic variability. Although there is no treatment to halt the progressive maculopathy, clinical management is directed toward treatment of amblyopia and surgical correction of certain complications. X-linked retinoschisis is an important condition to study, both to improve the clinical management of this disorder, and to better understand retinal function and development. Herein, we review the clinical, histopathologic, and molecular genetic and treatment options of X-linked retinoschisis.

Surgery in unilateral congenital cataract caused by persistent fetal vasculature or minimal fetal vascular remnants

PURPOSE

To document in detail the surgical management challenges over the wide spectrum of persistent fetal vasculature syndrome (PFVS).

SETTING

Department of Ophthalmology, University of Vienna, Medical School, Vienna, Austria.

METHODS

As part of an ongoing prospective clinical trial of the treatment and etiology of pediatric cataract, a subgroup of 31 children with unilateral cataract was defined. Standard surgical techniques were used based on age. Group 1 comprised infants between 0 and 1.5 years; Group 2, preschool children between 1.6 and 5.9 years; and Group 3, school-aged children between 6 and 16 years. Additional surgical procedures were used based on the degree of PFVS.

RESULTS

All 31 eyes with unilateral cataract showed signs of PFVS. Characteristic features were found in 75% of eyes in Group 1, 8% of eyes in Group 2, and 67% of eyes in Group 3. Minimal fetal vascular remnants were found in 92%, 25%, and 33%, respectively. Correct diagnosis of PFVS was made preoperatively in 56% of eyes in Group 1, 8% in Group 2, and 67% in Group 3. Surgical procedures in addition to standard age-related techniques were necessary in all eyes with unilateral cataract.

CONCLUSIONS

Results indicate that varying degrees of PFVS are a frequent cause of unilateral congenital cataract. Most severe cases were in infants, and preschool children were usually mildly affected. Vitreoretinal complications may lead to challenges in the surgical management in infants. In preschool children, cataract surgery must be performed in a guarded fashion because of the high risk for preexisting posterior capsule breaks due to minimal fetal vascular remnants.

Persistência hiperplástica do vítreo primitivo: avaliação por métodos de imagem

Persistência hiperplásica do vítreo primitivo (PHVP) é um desenvolvimento anormal, afetando crianças, resultante da falha de regressão do vítreo primitivo e dos vasos hialóides, com proliferação de tecido conectivo. A PHVP pode ter três variações: uma anterior, outra posterior e uma terceira com a combinação das duas. Clinicamente manifesta-se como leucocoria (reflexo branco pupilar) em um olho de dimensões reduzidas. Esta anomalia é usualmente unilateral e não associada com outros achados sistêmicos. Leucocoria, descolamento de retina, pregas retinianas e catarata podem confundir PHVP com outras afecções oculares que têm achados semelhantes. Retinoblastoma, catarata congênita, retinopatia da prematuridade e pseudogliomas são doenças com achados semelhantes aos da PHVP. A visualização direta dos remanescentes do sistema vascular hialóide fetal é a melhor evidência da lesão presente, se não fosse, muitas vezes impossivel, à fundoscopia, devido à opacidade do tecido. Nestes casos, a visualização indireta, por meio de ultra-sonografia, tomografia computadorizada e ressonância magnética, fornece o diagnóstico. As imagens obtidas por estes métodos proporcionam, ainda, informações e diagnóstico diferencial com outras doenças, particularmente com o retinoblastoma. Os autores fazem uma revisão na literatura e apresentam um estudo iconográfico das imagens e achados da PHVP.

Tubedown-1 in remodeling of the developing vitreal vasculature in vivo and regulation of capillary outgrowth in vitro

Tubedown-1 (tbdn-1) is a mammalian homologue of the N-terminal acetyltransferase subunit NAT1 of Saccharomyces cerevisiae and copurifies with an acetyltransferase activity. Tbdn-1 expression in endothelial cells becomes downregulated during the formation of capillary-like structures in vitro and is regulated in vivo in a manner which suggests a functional role in dampening blood vessel development. Here we show that tbdn-1 is expressed highly in the vitreal vascular network (tunica vasculosa lentis and vasa hyaloidea propria) during the pruning and remodeling phases of this transient structure. The vitreal blood vessels of mice harboring a targeted inactivation of TGF-beta2 fail to remodel and abnormally accumulate, a phenomenon reminiscent of the ocular pathology resembling persistent fetal vasculature (PFV) in humans. Since suppression of normal tbdn-1 expression has been previously observed in retinal vessel proliferation, we analyzed vitreal vascular changes and tbdn-1 expression in TGF-beta2(-/-) eyes. The nuclei of vitreal vessel endothelial cells in TGF-beta2(-/-) eyes express proliferating cell nuclear antigen (PCNA) and exhibit increased levels of active (P42/44)mitogen-activated protein kinase (phospho-(P42/44)MAPK), characteristics consistent with proliferative endothelial cells. In contrast to normal vitreal vessels, collagen IV expression exhibited a disorganized pattern in the TGF-beta2(-/-) vitreal vessels, suggesting vessel disorganization and possibly a breakdown of vessel basal laminae. Moreover, vitreal vessels of TGF-beta2(-/-) mice lack expression of pericyte markers (CD13, alpha smooth muscle actin) and show ultrastructural changes consistent with pericyte degeneration. The accumulating vitreal blood vessels of TGF-beta2(-/-) mice, while maintaining expression of the endothelial marker von Willebrand Factor, show a significant decrease in the expression of tbdn-1. We addressed the functional role of tbdn-1 in the regulation of vitreal blood vessels using an in vitro model of choroid-retina capillary outgrowth. Clones of the RF/6A fetal choroid-retina endothelial cell line showing suppression of tbdn-1 levels after overexpression of an antisense TBDN-1 cDNA display a significant increase in the formation of capillary-like structures in vitro compared with controls. These findings suggest that tbdn-1 inhibits capillary-like formation in vitro and may serve to dampen vitreal blood vessel formation preceding the regression of the vitreal vasculature during development. Our results also suggest that tbdn-1 may participate with TGF-beta2 in regulating normal development of the vitreal vasculature.

Arteriolar and venular patterning in retinas of mice selectively expressing VEGF isoforms

The murine VEGF gene is alternatively transcribed to yield the VEGF(120), VEGF(164), and VEGF(188) isoforms, which differ in their potential to bind to heparan sulfate and neuropilin-1 and to stimulate endothelial growth. Here, their role in retinal vascular development was studied in mice selectively expressing single isoforms. VEGF(164/164) mice were normal, healthy, and had normal retinal angiogenesis. In contrast, VEGF(120/120) mice exhibited severe defects in vascular outgrowth and patterning, whereas VEGF(188/188) mice displayed normal venular outgrowth but impaired arterial development. It is noteworthy that neuropilin-1, a receptor for VEGF(164), was predominantly expressed in retinal arterioles. These findings reveal distinct roles of the various VEGF isoforms in vascular patterning and arterial development in the retina.

Arteriolar and venular patterning in retinas of mice selectively expressing VEGF isoforms

The murine VEGF gene is alternatively transcribed to yield the VEGF(120), VEGF(164), and VEGF(188) isoforms, which differ in their potential to bind to heparan sulfate and neuropilin-1 and to stimulate endothelial growth. Here, their role in retinal vascular development was studied in mice selectively expressing single isoforms. VEGF(164/164) mice were normal, healthy, and had normal retinal angiogenesis. In contrast, VEGF(120/120) mice exhibited severe defects in vascular outgrowth and patterning, whereas VEGF(188/188) mice displayed normal venular outgrowth but impaired arterial development. It is noteworthy that neuropilin-1, a receptor for VEGF(164), was predominantly expressed in retinal arterioles. These findings reveal distinct roles of the various VEGF isoforms in vascular patterning and arterial development in the retina.