Hereditary microphthalmia with colobomatous cyst

Clinical and Demographic Profile of Uveal Coloboma: A hospital-based Study of 14,371 eyes of 9557 Indian Patients

OBJECTIVE

To describe the demographics and clinical profile of uveal coloboma in patients presenting to a multi-tier ophthalmology hospital network in India.

DESIGN

Cross- sectional hospital -based study.

METHODS

This cross-sectional hospital-based study included 2,817,766 new patients presenting between August 2010 and May 2021. Patients with a clinical diagnosis of uveal coloboma in at least one eye were included as cases. The data were collected using an electronic medical record system.

RESULTS

Overall, 9,557 (0.34%) patients were diagnosed with uveal coloboma. Just over half of the patients were male (51.82%) and had bilateral (50.37%) affliction. The most common age group at presentation was during the second decade of life with 2,198 (23%) patients. The overall prevalence was higher in patients from a lower socio-economic status (0.53%) and presenting from the rural geography (0.39%). The most common type was retino-choroidal coloboma in 8,049 (84.22%) patients followed by iris coloboma in 2,129 (22.28%) patients. The most common Ida Mann classification in the eyes with retino-choroidal coloboma was type 4 in 7,049 (57.23%) eyes followed by type 2 in 3,685 (29.92%) eyes. In the 14,371 eyes, 5,696 (39.64%) eyes had a visual impairment of blindness (>20/400) followed by mild or no visual impairment (<20/70) in 2,875 (20.01%) eyes. In the 2,228 (15.5%) eyes that required a surgical/ laser intervention, cataract surgery was performed in 951 (6.62%) eyes, vitreo-retinal surgery in 661 (4.6%) eyes followed by laser photocoagulation in 357 (2.48%) eyes.

CONCLUSION

Uveal Coloboma is more common in males, is predominantly bilateral in the population studied. It is more commonly found in patients from lower socio-economic strata and from a rural background. The most common type is retino-choroidal coloboma and over a third of the eyes are affected with blindness.

Cataract surgery in eyes with congenital ocular coloboma

PURPOSE

To assess the safety, efficacy, and complication rate of phacoemulsification and intraocular lens (IOL) implantation in patients with congenital uveal coloboma and to evaluate the role of pupilloplasty.

METHODS

A retrospective review of 41 eyes (31 patients) with congenital coloboma that underwent phacoemulsification and IOL implantation between September 2012 and September 2018. Preoperative, intraoperative, and postoperative data were collected for analysis.

RESULTS

The mean patient age at surgery was 53.9 years (range 15-82). The primary indication for surgery was cataract removal for visual improvement, and lens subluxation was additionally present in two eyes (5%) preoperatively. The mean preoperative corrected distance visual acuity (CDVA) was 0.90 LogMAR. Phacoemulsification surgery was performed in all cases and nine eyes (22%) had pupilloplasty for pupil reconstitution at the time of the procedure. Surgeon grade varied from trainee surgeon under supervision to consultant. Eight patients (19.5%) had posterior capsular rupture (PCR) with or without vitreous loss requiring anterior vitrectomy. Of these, 2 cases (5%) had dropped nuclear fragments requiring subsequent pars plana vitrectomy and lens fragment removal. The mean postoperative CDVA was 0.62 LogMAR (p = 0.0003).

CONCLUSION

Patients with iridolenticular choroidal coloboma appear to be more at risk of complications, as were cases performed by non-consultant surgeons. Contrary, patients with phakodonesis, preoperative anterior chamber vitreous, dense cataracts, and cases were iris hooks used had no significant difference at PCR rate. The risk of postoperative glare and pupilloplasty needs to be considered in cases with good visual potential to avoid a possible second procedure.

Ocular coloboma: Genetic variants reveal a dynamic model of eye development

Ocular coloboma is a congenital disorder of the eye where a gap exists in the inferior retina, lens, iris, or optic nerve tissue. With a prevalence of 2-19 per 100,000 live births, coloboma, and microphthalmia, an associated ocular disorder, represent up to 10% of childhood blindness. It manifests due to the failure of choroid fissure closure during eye development, and it is a part of a spectrum of ocular disorders that include microphthalmia and anophthalmia. Use of genetic approaches from classical pedigree analyses to next generation sequencing has identified more than 40 loci that are associated with the causality of ocular coloboma. As we have expanded studies to include singleton cases, hereditability has been very challenging to prove. As such, researchers over the past 20 years, have unraveled the complex interrelationship amongst these 40 genes using vertebrate model organisms. Such research has greatly increased our understanding of eye development. These genes function to regulate initial specification of the eye field, migration of retinal precursors, patterning of the retina, neural crest cell biology, and activity of head mesoderm. This review will discuss the discovery of loci using patient data, their investigations in animal models, and the recent advances stemming from animal models that shed new light in patient diagnosis.

An update on the genetics of ocular coloboma

Ocular coloboma is an uncommon, but often severe, sight-threatening condition that can be identified from birth. This congenital anomaly is thought to be caused by maldevelopment of optic fissure closure during early eye morphogenesis. It has been causally linked to both inherited (genetic) and environmental influences. In particular, as a consequence of work to identify genetic causes of coloboma, new molecular pathways that control optic fissure closure have now been identified. Many more regulatory mechanisms still await better understanding to inform on the development of potential therapies for patients with this malformation. This review provides an update of known coloboma genes, the pathways they influence and how best to manage the condition. In the age of precision medicine, determining the underlying genetic cause in any given patient is of high importance.

Ocular manifestations of PACS1 mutation

Heterozygous mutation in the PACS1 (phosphofurin acidic cluster sorting proteins 1) gene is a known cause of developmental delay, multiple congenital anomalies, dysmorphism, and ocular abnormalities. We present the case of an affected 10-year-old girl, conceived by assisted reproductive technology, who has ocular coloboma and findings characteristic of PACS1 mutation.

An unusual presentation of Kabuki syndrome with orbital cysts, microphthalmia, and cholestasis with bile duct paucity

Kabuki syndrome (KS) is a rare developmental disorder characterized by multiple congenital malformations, postnatal growth retardation, intellectual disability, and recognizable facial features. It is mainly caused by mutations in either KMT2D or KDM6A. We describe a 14-year-old boy with KS presenting with an unusual combination of bilateral microphthalmia with orbital cystic venous lymphatic malformation and neonatal cholestasis with bile duct paucity, in addition to the typical clinical features of KS. We identified the novel KMT2D mutation c.10588delC, p.(Glu3530Serfs*128) by Mendeliome (Illumina TruSight One®) sequencing, a next generation sequencing panel targeting 4,813 genes linked to human genetic disease. We analyzed the Mendeliome data for additional mutations which might explain the exceptional clinical presentation of our patient but did not find any, leading us to suspect that the above named symptoms might be part of the KMT2D-associated spectrum of anomalies. We thus extend the range of KS-associated malformations and propose a hypothetical connection between KMT2D and Notch signaling. © 2016 Wiley Periodicals, Inc.

Neural crest derivatives in ocular development: discerning the eye of the storm

Neural crest cells (NCCs) are vertebrate-specific transient, multipotent, migratory stem cells that play a crucial role in many aspects of embryonic development. These cells emerge from the dorsal neural tube and subsequently migrate to different regions of the body, contributing to the formation of diverse cell lineages and structures, including much of the peripheral nervous system, craniofacial skeleton, smooth muscle, skin pigmentation, and multiple ocular and periocular structures. Indeed, abnormalities in neural crest development cause craniofacial defects and ocular anomalies, such as Axenfeld-Rieger syndrome and primary congenital glaucoma. Thus, understanding the molecular regulation of neural crest development is important to enhance our knowledge of the basis for congenital eye diseases, reflecting the contributions of these progenitors to multiple cell lineages. Particularly, understanding the underpinnings of neural crest formation will help to discern the complexities of eye development, as these NCCs are involved in every aspect of this process. In this review, we summarize the role of ocular NCCs in eye development, particularly focusing on congenital eye diseases associated with anterior segment defects and the interplay between three prominent molecules, PITX2, CYP1B1, and retinoic acid, which act in concert to specify a population of neural crest-derived mesenchymal progenitors for migration and differentiation, to give rise to distinct anterior segment tissues. We also describe recent findings implicating this stem cell population in ocular coloboma formation, and introduce recent evidence suggesting the involvement of NCCs in optic fissure closure and vascular development.

Prenatal diagnosis of colobomatous microphthalmos

Optic nerve coloboma and microphthalmos with colobomatous cyst are rare congenital anomalies that are difficult to detect on prenatal ultrasonography and magnetic resonance imaging. Only four cases of optic nerve coloboma and two cases of microphthalmos with colobomatous cyst have been detected on prenatal imaging. The authors report a case of a fetus initially suspected to have retinoblastoma of the right eye on prenatal ultrasonography who was later diagnosed as having microphthalmos on fetal magnetic resonance imaging. Following delivery, she was noted to have microphthalmos with colobomatous cyst of the right eye and optic nerve coloboma of the left eye. The authors also review the prenatal ocular imaging findings of the differential diagnosis.

Sox4 regulates choroid fissure closure by limiting Hedgehog signaling during ocular morphogenesis

SoxC transcription factors play critical roles in many developmental processes, including neurogenesis, cardiac formation, and skeletal differentiation. In vitro and in vivo loss-of-function studies have suggested that SoxC genes are required for oculogenesis; however the mechanism was poorly understood. Here, we have explored the function of the SoxC factor Sox4 during zebrafish eye development. We show that sox4a and sox4b are expressed in the forebrain and periocular mesenchyme adjacent to the optic stalk during early eye development. Knockdown of sox4 in zebrafish resulted in coloboma, a structural malformation of the eye that is a significant cause of pediatric visual impairment in humans, in which the choroid fissure fails to close. Sox4 morphants displayed altered proximo-distal patterning of the optic vesicle, including expanded pax2 expression in the optic stalk, as well as ectopic cell proliferation in the retina. We show that the abnormal ocular morphogenesis observed in Sox4-deficient zebrafish is caused by elevated Hedgehog (Hh) signaling, and this is due to increased expression of the Hh pathway ligand Indian Hedgehog b (ihhb). Consistent with these results, coloboma in sox4 morphants could be rescued by pharmacological treatment with the Hh inhibitor cyclopamine, or by co-knockdown of ihhb. Conversely, overexpression of sox4 reduced Hh signaling and ihhb expression, resulting in cyclopia. Finally, we demonstrate that sox4 and sox11 have overlapping, but not completely redundant, functions in regulating ocular morphogenesis. Taken together, our data demonstrate that Sox4 is required to limit the extent of Hh signaling during eye development, and suggest that mutations in SoxC factors could contribute to the development of coloboma.

A missense mutation in ALDH1A3 causes isolated microphthalmia/anophthalmia in nine individuals from an inbred Muslim kindred

Nine affected individuals with isolated anophthalmia/microphthalmia from a large Muslim-inbred kindred were investigated. Assuming autosomal-recessive mode of inheritance, whole-genome linkage analysis, on DNA samples from four affected individuals, was undertaken. Homozygosity mapping techniques were employed and a 1.5-Mbp region, homozygous in all affected individuals, was delineated. The region contained nine genes, one of which, aldehyde dehydrogenase 1 (ALDH1A3), was a clear candidate. This gene seems to encode a key enzyme in the formation of a retinoic-acid gradient along the dorsoventral axis during an early eye development and the development of the olfactory system. Sanger sequence analysis revealed a missense mutation, causing a substitution of valine (Val) to methionine (Met) at position 71. Analyzing the p.Val71Met missense mutation using standard open access software (MutationTaster online, PolyPhen, SIFT/PROVEAN) predicts this variant to be damaging. Enzymatic activity, studied in vitro, showed no changes between the mutated and the wild-type ALDH1A3 protein.

Bilateral chorioretinal coloboma discovered with ultra-wide field retinal imaging

Uveal coloboma results from incomplete closure of the optic cup fissure. While conducting an evaluation of a new ultra-wide field retinal imaging camera (Optomap), which provides a view of the fundus up to 200° at one time without mydriasis, we discovered a case of bilateral chorioretinal coloboma in a 21-year-old student. The lesion was located in the midperiphery of each eye less than 2 disc diameters (DD) below the optic disc in the inferonasal quadrants. The size of the coloboma in the right eye was 1.8 DD in height and 1.3 DD in width, while the left lesion was 2.4 DD in height and 2.6 DD in width. The subject was totally asymptomatic and without any complication such as retinal detachment or choroidal neovascularization, which often accompany this type of lesion. The visual field of each eye displayed an absolute scotoma corresponding to the size and location of the coloboma. No management was necessary but the subject was advised to report for visual examination at regular intervals because complications can occur at any age.

Anophthalmos, microphthalmos, and Coloboma in the United kingdom: clinical features, results of investigations, and early management

PURPOSE

To describe the clinical features of children with anophthalmos, microphthalmos, and typical coloboma (AMC).

DESIGN

Descriptive, observational, cross-sectional study of the United Kingdom.

PARTICIPANTS

A total of 135 children with AMC newly diagnosed over an 18-month period beginning in October 2006.

METHODS

Cases were identified using active surveillance through an established ophthalmic surveillance system. Eligible cases were followed up 6 months after first notification.

MAIN OUTCOME MEASURES

Phenotypic characteristics, both ocular and systemic, clinical investigations, causes, and interventions.

RESULTS

A total of 210 eyes (of 135 children) were affected by AMC, of which 153 had isolated coloboma or coloboma with microphthalmos. The most common colobomatous anomaly was a chorioretinal defect present in 109 eyes (71.2%). Some 44% of children were bilaterally visually impaired. Systemic abnormalities were present in 59.7% of children, with craniofacial anomalies being the most common. Children with bilateral disease had a 2.7 times higher odds (95% confidence interval, 1.3-5.5, P = 0.006) of having systemic involvement than unilaterally affected children. Neurologic imaging was the most frequent investigation (58.5%) performed. Less than one third (30.3%) of the children with microphthalmos had ocular axial lengths measured. Eight children had confirmed genetic mutations. Approximately half (49.2%) of the children required ocular intervention.

CONCLUSIONS

Colobomatous defects were the most common phenotype within this spectrum of anomalies in the United Kingdom. The high frequency of posterior segment colobomatous involvement means that a dilated fundal examination should be made in all cases. The significant visual and systemic morbidity in affected children underlines the importance of a multidisciplinary approach to management.

Toward a better understanding of human eye disease insights from the zebrafish, Danio rerio

Visual impairment and blindness is widespread across the human population, and the development of therapies for ocular pathologies is of high priority. The zebrafish represents a valuable model organism for studying human ocular disease; it is utilized in eye research to understand underlying developmental processes, to identify potential causative genes for human disorders, and to develop therapies. Zebrafish eyes are similar in morphology, physiology, gene expression, and function to human eyes. Furthermore, zebrafish are highly amenable to laboratory research. This review outlines the use of zebrafish as a model for human ocular diseases such as colobomas, glaucoma, cataracts, photoreceptor degeneration, as well as dystrophies of the cornea and retinal pigmented epithelium.

Expression profiling during ocular development identifies 2 Nlz genes with a critical role in optic fissure closure

The gene networks underlying closure of the optic fissure during vertebrate eye development are poorly understood. Here, we profile global gene expression during optic fissure closure using laser capture microdissected (LCM) tissue from the margins of the fissure. From these data, we identify a unique role for the C(2)H(2) zinc finger proteins Nlz1 and Nlz2 in normal fissure closure. Gene knockdown of nlz1 and/or nlz2 in zebrafish leads to a failure of the optic fissure to close, a phenotype which closely resembles that seen in human uveal coloboma. We also identify misregulation of pax2 in the developing eye of morphant fish, suggesting that Nlz1 and Nlz2 act upstream of the Pax2 pathway in directing proper closure of the optic fissure.

Developmental abnormalities of the optic nerve and chiasm

Developmental anomalies of the optic nerve are an important and growing cause of lifelong visual handicap and they are often associated with systemic abnormalities. This review focuses on the ocular and systemic aspects of developmental anomalies arising from defects of fetal fissure closure and retinal ganglion cell development, and covers some other optic-disc anomalies that have systemic significance.

GDF6, a novel locus for a spectrum of ocular developmental anomalies

Colobomata represent visually impairing ocular closure defects that are associated with a diverse range of developmental anomalies. Characterization of a chromosome 8q21.2-q22.1 segmental deletion in a patient with chorioretinal coloboma revealed elements of nonallelic homologous recombination and nonhomologous end joining. This genomic architecture extends the range of chromosomal rearrangements associated with human disease and indicates that a broader spectrum of human chromosomal rearrangements may use coupled homologous and nonhomologous mechanisms. We also demonstrate that the segmental deletion encompasses GDF6, encoding a member of the bone-morphogenetic protein family, and that inhibition of gdf6a in a model organism accurately recapitulates the proband's phenotype. The spectrum of disorders generated by morpholino inhibition and the more severe defects (microphthalmia and anophthalmia) observed at higher doses illustrate the key role of GDF6 in ocular development. These results underscore the value of integrated clinical and molecular investigation of patients with chromosomal anomalies.

Microphthalmos: clinical and ultrasonographic findings

We analyzed ocular and ultrasonographic findings of microphthalmos and associated ocular and systemic pathologies in 27 microphthalmic eyes. A high incidence of consanguinous marriages (26%) was present among the parents of patients. Associated systemic abnormalities were growth retardation, congenital rubella, cleft lip and palate, facial hemangioma, inguinal hernia, clinodactyly, Hurler syndrome, Goltz-Gorlin syndrome and Hallermann-Streiff syndrome. A variety of ocular/systemic abnormalities were encountered. Early ultrasonographic diagnosis and description of other ocular and systemic pathologies are essential.

Ependymal tissue in microphthalmia with cyst

PURPOSE

To report the nature of the contents of a cyst associated with microphthalmia and optic nerve coloboma in a male infant.

DESIGN

Clinicopathologic report.

CASE REPORT

A male infant in good general health presented with a massively swollen, protruded left lower eyelid since birth. The globe was not identifiable. MRI disclosed a microphthalmic globe in the upper nasal orbit and an orbital cystic mass consisting of various compartments. Examination of the fellow eye showed a large optic nerve coloboma. As the protrusion of the left lower eyelid was progressive, aspiration of the cyst was performed twice. Finally, the cyst was removed surgically due to repeated filling.

RESULTS

Examination of the aspirated fluid showed resemblance to cerebrospinal fluid (CSF). During surgery, the cyst was not found to communicate with the cerebrospinal fluid system. However, tissue resembling choroidal plexus lined the wall of the cyst that was adherent to the optic nerve. Histological evaluation of the tissue revealed ependymal cells.

DISCUSSION

The presence of CSF in microphthalmic cysts does not necessarily imply a connection to the CNS, but may be due to local CSF production by ectopic ependymal cells.

Uveal coloboma: clinical and basic science update

PURPOSE OF REVIEW

To integrate knowledge on the embryologic and molecular basis of optic fissure closure with clinical observations in patients with uveal coloboma.

RECENT FINDINGS

Closure of the optic fissure has been well characterized and many genetic alterations have been associated with coloboma; however, molecular mechanisms leading to coloboma remain largely unknown. In the past decade, we have gained better understanding of genes critical to eye development; however, mutations in these genes have been found in few individuals with coloboma. CHD7 mutations have been identified in patients with CHARGE syndrome (coloboma, heart defects, choanal atresia, retarded growth, genital anomalies, and ear anomalies or deafness). Animal models are bringing us closer to a molecular understanding of optic fissure closure.

SUMMARY

Optic fissure closure requires precise orchestration in timing and apposition of two poles of the optic cup. The relative roles of genetics and environment on this process remain elusive. While most cases of coloboma are sporadic, autosomal dominant, autosomal recessive, and X-linked inheritance patterns have been described. Genetically, colobomata demonstrate pleiotropy, heterogeneity, variable expressivity, and reduced penetrance. Coloboma is a complex disorder with a variable prognosis and requires regular examination to optimize visual acuity and to monitor for potential complications.

Birth characteristics of different ocular congenital abnormalities in hungary

AIMS

The aim of the study was to estimate the prevalence at birth of different ocular congenital abnormalities and to describe their birth characteristics in Hungary.

METHODS

Two data sets were evaluated: the national-based Hungarian Congenital Abnormality Registry and the Hungarian Case-Control Surveillance of Congenital Abnormalities which include cases with ocular abnormalities and patient controls with other (non-ocular) congenital abnormalities, and population controls without abnormalities from the National Birth Registry.

RESULTS

Seven hundred twelve cases were found with ocular abnormalities in the data set of the Hungarian Congenital Abnormality Registry (2.62 per 10,000 live births), while that of the Hungarian Case-Control Surveillance of Congenital Abnormalities included 314 cases with ocular defects among 2.7 million live births in Hungary between 1980 and 2002. There was an obvious underascertainment and/or notification of cases with ocular defects because an extra effort to ascertain all cases with ocular abnormalities resulted in a birth prevalence of 6.31 per 10,000 live births in 1999. The main birth characteristics of cases were male excess, shorter mean gestational age and smaller mean birth weight with a larger proportion of preterm birth and low birthweight.

CONCLUSIONS

Earlier diagnosis of ocular abnormalities is necessary with a more complete notification of these cases to the Hungarian Congenital Abnormality Registry. The birth characteristics of cases with ocular abnormalities may have some associations with the origin of ocular defects; therefore, these variables will require further studies in case-control approach.

Ocular coloboma: a reassessment in the age of molecular neuroscience

Congenital colobomata of the eye are important causes of childhood visual impairment and blindness. Ocular coloboma can be seen in isolation and in an impressive number of multisystem syndromes, where the eye phenotype is often seen in association with severe neurological or craniofacial anomalies or other systemic developmental defects. Several studies have shown that, in addition to inheritance, environmental influences may be causative factors. Through work to identify genes underlying inherited coloboma, significant inroads are being made into understanding the molecular events controlling closure of the optic fissure. In general, severity of disease can be linked to the temporal expression of the gene, but this is modified by factors such as tissue specificity of gene expression and genetic redundancy.

Gorlin syndrome: the PTCH gene links ocular developmental defects and tumour formation

AIM

To identify a gene linking microphthalmia with cyst with early onset medulloblastoma.

METHODS

Mutation analysis of the PTCH gene.

RESULTS

A mutation in exon 10 of the PTCH gene was identified, confirming a diagnosis of Gorlin syndrome.

CONCLUSIONS

This is the first genetically identified mutation giving rise to microphthalmia with cyst and provides a valuable link in the eye developmental gene pathway.

Orbital cysts of childhood—classification, clinical features, and management

There is little in the literature about the clinical spectrum of orbital cysts of childhood and no comprehensive classification has been proposed. The authors propose a classification of orbital cysts of childhood and review their clinical features, pathology, and management. The major categories in the classification include cysts of surface epithelium, teratomatous cysts, neural cysts, secondary cysts, inflammatory cysts, and noncystic lesions with cystic component. Cysts of the surface epithelium are further divided into simple epithelial cyst (epidermal, conjunctival, respiratory, and apocrine gland), and dermoid cyst (epidermal and conjunctival). Epidermal dermoid cyst (dermoid) is by far the most common orbital cystic lesion in children, accounting for over 40% of all orbital lesions of childhood and for 89% of all orbital cystic lesions of childhood that come to biopsy or surgical removal. Neural cysts include those associated with ocular maldevelopment (congenital cystic eye and colobomatous cyst) and those associated with brain and meningeal tissue (cephalocele and optic nerve meningocele). The most important secondary cyst is mucocele that can occur in children with cystic fibrosis. Inflammatory cysts are generally due to parasitic infestations and are more common in tropical areas of the world. Noncystic lesions that can have a cystic component include adenoid cystic carcinoma, rhabdomyosarcoma, lymphangioma, and others. Each type of cyst has rather characteristic, but not pathognomonic, clinical features. Computed tomography and magnetic resonance imaging can help differentiate a cystic lesion from a solid tumor, suggest the type of cyst, and help in planning management. The pathology varies with the cells that line the cyst and with the inflammatory agent. Management varies from local excision to observation, depending on the location and type of cyst. Orbital cysts of childhood can be classified into categories, based mainly on their histopathology. The clinical, radiologic, and histopathologic features can be correlated with the classification in order to better evaluate a child with a cystic lesion in the orbit.

Ocular and systemic findings associated with optic disc colobomas

PURPOSE

To determine the ocular and systemic anomalies associated with optic disc colobomas.

PATIENTS AND METHODS

The records of patients with a diagnosis of isolated optic disc coloboma and chorioretinal coloboma with optic disc involvement were retrospectively reviewed.

RESULTS

Fifteen patients were included in the study. Of the 30 eyes, the optic disc and choroid were involved in 18, an isolated disc coloboma was present in 5, a normal optic disc was present in 4, and the optic disc could not be identified because of extreme microphthalmia in 1. Of the optic discs outside the fundus colobomas, 1 had an abnormal shape and 1 had optic atrophy and hypoplasia. Eight patients had bilateral but asymmetric involvement of the optic nerve with the coloboma. Fourteen eyes of 9 patients were microphthalmic. Nine eyes of 6 patients had microcornea. One patient had a nonrhegmatogenous retinal detachment at the time of diagnosis. One eye had a retrobulbar cyst with microphthalmia. Eight (53%) of the patients had sensory strabismus. Two patients had unilateral cortical lens opacities. Associated systemic findings were present in 6 (40%) of the 15 patients.

CONCLUSIONS

Optic disc colobomas have a wide variety of presentations. Poor visual acuity was observed mostly in eyes with macular involvement and microphthalmia.

The familial contribution to non-syndromic ocular coloboma in south India

AIMS

To identify the proportion of familial cases of isolated ocular colobomatous malformations in a case series from south India.

METHODS

Children with ocular coloboma without systemic features were recruited from multiple sources in Andhra Pradesh, India. Their families were traced, pedigrees drawn, and family members examined.

RESULTS

56 probands, 25 females (44.6%) and 31 males (57.4%) with a colobomatous malformation were identified. In 12 cases (21.4%) another family member was affected. The risk to siblings was 3.8%. The parents were consanguineous in 25 cases (44.6%).

CONCLUSIONS

21.4% of cases of isolated ocular coloboma in this highly consanguineous population of south India were familial, with both autosomal dominant and autosomal recessive mechanisms likely in different families.

Ocular colobomata

Ocular colobomata present diagnostic and therapeutic challenges in patients of all ages, but especially in young children. The "typical" coloboma, caused by defective closure of the fetal fissure, is located in the inferonasal quadrant, and it may affect any part of the globe traversed by the fissure from the iris to the optic nerve. Ocular colobomata are often associated with microphthalmia, and they may be idiopathic or associated with various syndromes. Types and severity of complications vary depending on the location and size of the colobomata. This article reviews the pathogeneses, categorization, genetic bases, differential diagnoses and management of ocular coloboma.

Visual acuity in children with coloboma: clinical features and a new phenotypic classification system

OBJECTIVE

The aims of this study were to describe the clinical features and biometric findings in the eyes of children with coloboma and to develop a classification of coloboma that correlates with visual function.

DESIGN

Retrospective observational case series.

PARTICIPANTS

One hundred thirteen children and young adults (48 female, 65 male) aged 0 to 20 years with 196 eyes having coloboma.

METHODS

Children with coloboma were recruited from schools for the blind, integrated education programs, schools for the mentally handicapped, community-based rehabilitation services, and hospital clinics in Andhra Pradesh, India, between January 1998 and January 1999. Visual function was assessed, including distance and near visual acuity (VA), and navigational vision. The corneal diameter and axial length of eyes were measured wherever possible.

MAIN OUTCOME MEASURES

Anatomic site of coloboma, association with microcornea and/or microphthalmos, VA, presence of navigational vision and reading vision.

RESULTS

Of 196 eyes with colobomatous malformations, 11 had microphthalmos with cyst, and 185 eyes had coloboma (associated with microcornea in 155 eyes and with a normal corneal diameter in 30). Microphthalmos was present in 72 of the 185 eyes with coloboma, of which 71 of 72 also had microcornea. The prognosis for vision depended on the phenotype of the better eye. Microphthalmos with cyst had the worst prognosis (VA < 3/60, 100%; reading and navigational vision, 0%). Microcornea with microphthalmos had a worse prognosis than microcornea without microphthalmos (VA < 3/60: 66.7% vs. 23.3%; unable to read N10: 66.7% vs. 34.1 %; no navigational vision: 30.6% vs. 6.73%). Simple coloboma (no microcornea or microphthalmos) had the best prognosis (VA < 3/60: 6.7%; able to read N10: 93.3%; navigational vision: 100%). A corneal diameter <6 mm had a poor visual prognosis, whereas a corneal diameter >10 mm had a good prognosis.

CONCLUSIONS

A phenotypic classification of coloboma is proposed, which in this study showed a good correlation with visual acuity, reading, and navigational vision. Microphthalmos with cyst had the worst prognosis, coloboma with microcornea and microphthalmos a poor prognosis, coloboma with only microcornea had an intermediate prognosis, and simple coloboma had the best prognosis.

A case of microphthalmos with cyst and partial trisomy 22

A 13-day-old girl was referred for evaluation of a right orbital mass. Ophthalmic examinations revealed microphthalmia with cyst in the right eye and microphthalmia in the left eye. She had lowset ears, auricular fistula, micrognathia, and muscular hypotonia. Chromosomal analysis using fluorescence in-situ hybridization (FISH) showed partial trisomy 22. To our knowledge, microphthalmos with cyst associated with partial trisomy 22 has not been described previously in the English literature. Repeated aspiration resulted in a decrease in size of the cyst.

Classification of microphthalmos and coloboma

A new classification of microphthalmos and coloboma is proposed to bring order to the complexity of clinical and aetiological heterogeneity of these conditions. A phenotypic classification is presented which may help the clinician to give a systematic description of the anomalies. The phenotype does not predict the aetiology but a systematic description of ocular and systemic anomalies improves syndrome identification. There are two major classes, total and partial microphthalmos, and a subclassification which follows the embryology of the anomalies. The aetiological classification consists of three classes: (1) genetic (monogenic and chromosomal), (2) prenatally acquired (teratological agents and intrauterine deformations), and (3) associations. Genetic disorders give rise to malformations; prenatally acquired anomalies are disruptions or deformations. The aetiological classification can be applied to other congenital birth defects and improves counselling of families. Recurrence risks vary considerably between the classes.