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PubMed2003

Coloboma of the crystalline lens.

BACKGROUND: Anomalies of crystalline lens shape and position include: lenticonus, lentiglobus, microspherophakia, coloboma, and ectopia lentis. Lens coloboma probably results from a localized absence or maldevelopment of lens zonules. It may be a variant of nontraumatic (congenital) ectopia lentis, in which the zonular deficiency is more generalized. Coloboma of the lens and nontraumatic ectopia lentis may occur in association with other ocular and systemic anomalies. A case of lens coloboma is presented, and lens coloboma, ectopia lentis, and associated ocular and systemic conditions are reviewed. CASE REPORT: A 36-year-old man came to us for routine evaluation. He was found to be moderately myopic. Post-dilated biomicroscopy revealed a crystalline lens coloboma O.D. Since the patient was tall and thin, and his chest X-ray demonstrated abnormal cardiovascular findings, Marfan's syndrome or another connective tissue disorder was suspected. No definitive diagnosis was established for the patient, but he later reported that his sister had Marfan's syndrome, renewing suspicion that he also had the condition. He was advised to wear polycarbonate spectacles and to avoid contact sports. CONCLUSIONS: Coloboma of the crystalline lens and nontraumatic ectopia lentis may occur in isolation or with other ocular pathologies, and may reflect an underlying systemic disorder. Optometric management must address safety issues to reduce the risk of retinal detachment and lens dislocation. Systemic evaluation should be pursued to rule out Marfan's syndrome and similar disorders. Genetic investigation and evaluation of family members may also be merited.

Adult↗
PubMed1999

Transgenic rescue of SNAP-25 restores dopamine-modulated synaptic transmission in the coloboma mutant.

Many of the molecular components constituting the exocytotic machinery responsible for neurotransmitter release have been identified, yet the precise role played by these proteins in synaptic transmission, and their impact on neural function, has not been resolved. The mouse mutation coloboma is a contiguous gene defect that leads to electrophysiological and behavioral deficits and includes the gene-encoding SNAP-25, an integral component of the synaptic vesicle-docking/fusion core complex. The involvement of SNAP-25 in the hyperactive behavior of coloboma mice, which can be ameliorated by the indirect dopaminergic agonist, amphetamine, has been demonstrated by genetic rescue using a SNAP-25 transgene. Coloboma mice also exhibit increased recurrent inhibition, reduced theta rhythm by tail-pinch and reduced long-term potentiation in the hippocampal dentate gyrus that, as the hyperkinesis seen in these mutants suggests, may reflect impaired monoaminergic modulation. We sought to identify neurophysiological correlates of the rescued hyperactivity within hippocampal synaptic circuitry of SNAP-25 transgenic coloboma mutant mice. In contrast to the differences between coloboma and wild-type mice, there was no significant difference in the duration or amplitude of theta rhythmic activity (4-6 Hz) induced by tail-pinch (10 s), afferent-evoked field potentials, or paired-pulse responses recorded in the dentate gyrus of SNAP-25 transgenic coloboma and wild-type mice. Amphetamine (3.0 mg/kg, i.p.) produced disinhibition of dentate paired-pulse responses in both SNAP-25 transgenic and wild-type mice but increased inhibition in non-transgenic coloboma mice. These findings support the hypothesis that alteration of monoaminergic neurotransmission, which can be reversed by the indirect agonist, amphetamine, is particularly sensitive to alterations in the expression of SNAP-25.

Amphetamine↗
PubMed1995

Coloboma hyperactive mutant exhibits delayed neurobehavioral developmental milestones.

The coloboma mutation (Cm) is a neutron-irradiation induced gene deletion located on the distal portion of mouse chromosome 2. This deletion region includes a gene encoding the synaptic vesicle docking fusion protein, synaptosomal-associated protein of 25 kDa (SNAP-25). The resulting mutation is semi-dominant with heterozygote mice exhibiting a triad of phenotypic abnormalities that comprise profound spontaneous hyperactivity, head bobbing and a prominent eye dysmorphology. Because the expression pattern of two SNAP-25 isoforms begins to change during the first postnatal week, neurobehavioral developmental milestones were examined in order to determine if the expression of the coloboma behavioral phenotype could be detected during this period of postnatal development. The early classification of coloboma mutant offspring may help to further describe the penetrance of this mutation as well as the contribution of developmental changes to the adult behavioral phenotype. The coloboma mutation resulted in delays in some tests of complex motor skills including righting reflex and bar holding. In addition, coloboma mutants were characterized by body weight differences (first appearance day 7) and hyperreactivity to touch (day 11) and head bobbing (day 14). These data demonstrate disruptions in the time course of attaining developmental milestones in coloboma mutants and provide further evidence supporting the hypotheses that alterations in Snap gene expression are associated with functional behavioral consequences in developing offspring.

Aging↗
PubMed2006

Abnormal latent inhibition and impulsivity in coloboma mice, a model of ADHD.

Attention deficit hyperactivity disorder (ADHD) is characterized by hyperactivity, inattention, and impulsivity. The coloboma mouse model of ADHD exhibits profound hyperactivity. To determine whether coloboma mice exhibit other signs of ADHD, we assessed latent inhibition as a test of attention, and impulsivity in a delayed reinforcement paradigm. Latent inhibition was present in control mice but was disrupted in coloboma mice. Coloboma mice also exhibited impaired performance on the delayed reinforcement task and were not able to wait as long as control mice to obtain the greater reinforcer. Because norepinephrine mediates hyperactivity in coloboma mice, we examined the role of norepinephrine in disrupted latent inhibition and impulsivity. Reduction of norepinephrine with DSP-4 (N-(2-chloroethyl)-N-ethyl-2-bromobenzylamine hydrochloride) restored latent inhibition but did not ameliorate impulsivity. In summary, coloboma mice exhibit hyperactivity, inattention as determined by latent inhibition, and impulsivity, and norepinephrine mediates hyperactivity and inattention but not impulsivity in these mice.

Animals↗
PubMed2001

Renal coloboma syndrome.

OBJECTIVE: To characterize the ocular features of renal coloboma syndrome. DESIGN: Prospective, observational case series. PARTICIPANTS: Twelve patients referred by the pediatric nephrology clinic and the ophthalmic records of five additional patients. METHODS: For each patient, age at the time of examination, gender, renal function, and presence of a mutation in the PAX2 gene were noted. All patients underwent measurement of visual acuity and anterior and posterior segment examination with fundus photography. Goldmann visual fields were tested in four cases. MAIN OUTCOME MEASURES: Visual acuity, optic disc abnormalities, and mutation in the PAX2 gene. RESULTS: Mean age was 21.5 years. Renal failure was mild in 6 patients and severe in 11 patients. A mutation in the PAX2 gene was identified in nine patients, without correlation to the ocular phenotype. Ocular features could be divided into five groups: optic disc dysplasia limited to an unusual pattern of retinal vessels without functional consequence; optic disc pit with normal visual acuity and blind spot enlargement; large optic disc coloboma; large coloboma of the optic disc and adjacent retina; morning glory anomaly (these last three conditions were accompanied by poor visual acuity). Fundus abnormalities were symmetrical in most cases and unrelated to renal status. CONCLUSIONS: Ophthalmic and renal characteristics of the renal coloboma syndrome are highly variable. The need for dialysis or renal transplantation can occur early in life or several years later. A wide range of ocular abnormalities located in the posterior segment can be observed. Mild optic disc dysplasia or pit have no functional consequence and can be underdiagnosed. More severe colobomas or related abnormalities, such as morning glory anomaly, often lead to poor visual acuity. Molecular biology allows detection of the mutations in the PAX2 gene, but can be negative in approximately 50% of cases. The observation of an optic disc coloboma or related abnormality stimulates the ophthalmologist to propose simple nephrologic investigations to check for renal hypoplasia, a potentially life-threatening disease. Conversely, renal hypoplasia stimulates the nephrologist to ask for a fundus examination to confirm the diagnosis and check for complications such as retinal detachment.

Abnormalities, Multiple↗
PubMed1998

Choroidal coloboma in two members of a family.

A family with choroidal coloboma is reported. A 43-year-old Japanese woman with choroidal coloboma including the optic disk and extending to the inferior half of the fundus in both eyes had horizontal nystagmus, microcornea and mild cortical cataract in both eyes. Her 40-year-old younger sister had choroidal colobomas in both eyes and also a horizontal nystagmus, microcornea in both eyes and a mature cataract in the left eye. They had no systemic abnormalities. Their parents and 2 younger sisters showed neither ocular nor systemic abnormalities. Choroidal coloboma with iris coloboma has been reported frequently, but familial choroidal coloboma without involvement of the iris and with no systemic abnormalities is rare.

Adult↗
PubMedDate not supplied

Maldevelopment of neural crest cells in patients with typical uveal coloboma.

PURPOSE: To clarify the pathogenesis of ocular and systemic anomalies associated with typical uveal coloboma. METHODS: The records of 72 patients with typical uveal coloboma (35 males and 37 females) treated at Nagoya City University Hospital during a 16-year period were reviewed. RESULTS: Typical uveal coloboma was bilateral in 33 patients and unilateral in 35 patients; 4 patients were unclassified because of severe contralateral microphthalmos. Uveal coloboma was an isolated defect in 23 (37%) patients. Other ocular anomalies were present in 19 (31%) patients, systemic anomalies were found in 7 (11%) patients, and both other ocular and systemic anomalies were noted in 13 patients (21%). The associated ocular anomalies included microphthalmos in 28 eyes of 23 patients, persistent pupillary membrane in 28 eyes of 18 patients, and posterior embryotoxon in 20 eyes of 15 patients. The accompanying systemic anomalies included ear anomalies, retarded growth, and retarded development in 18 patients; heart anomalies in 13 patients; genital hypoplasia in 12 patients; and congenital facial palsy in 10 patients. The collection of malformations known as the CHARGE association was diagnosed in 14 (19%) patients. CONCLUSION: Abnormal development of neural crest cells appeared to be responsible for the majority of associated ocular and systemic anomalies in patients in the present series, suggesting that typical uveal coloboma may be related to maldevelopment of the neural crest cells. The present findings indicated that ophthalmologists should be aware of the possible association of typical uveal coloboma with systemic anomalies.

Abnormalities, Multiple↗
PubMedDate not supplied

Isolated bilateral upper lid coloboma--a case report.

BACKGROUND: Congenital upper lid colobomas may be associated with ocular and systemic anomalies. This paper reports an isolated bilateral upper lid coloboma. METHOD: A report of a case of bilateral upper lid coloboma with discussion of relevant literature. RESULTS: A 5-month old healthy baby girl presented with isolated bilateral upper lid coloboma. The coloboma was as large as two thirds of each upper lid with symblepharon. She had no other associated congenital anomalies reported by various workers. The upper lid defect in each eye was repaired in two stages. She had a flap from the lower lid using the lid switch technique and flap separation 2 weeks after the first surgery, in a combined surgery by a plastic surgeon and ophthalmologists. A good functional and cosmetic result was achieved from the treatment. The patient was discharged five days after the second surgery. CONCLUSION: This case shows that lid coloboma could be an isolated problem in a child. Early and appropriate surgical intervention is necessary for good visual and functional outcome.

Coloboma↗
PubMed2005

Dynamic atypical optic nerve coloboma associated with transient macular detachment.

PURPOSE: Macular schisis or detachment is frequently observed in eyes with optic pits or colobomas. Although spontaneous resolution of the maculopathy has been reported, concurrent changes in the optic nerve coloboma have not. We report three cases of atypical optic nerve colobomas in which dynamic optic nerve changes coincide with the development and subsequent resolution of the associated maculopathy. METHODS: We reviewed the records of three patients with dynamic optic nerve changes associated with maculopathy. All patients were observed for at least 6 months. Fundus photography and fluorescein angiography were used to document the optic nerve and macular changes. RESULTS: Three patients were noted to have macular detachments without apparent optic nerve excavation. With observation, the maculopathy spontaneously resolved in each case. We documented concurrent optic nerve changes whereby atypical optic nerve colobomas became apparent over several months in all cases. In one case, we noted the simultaneous development of maculopathy in association with obscuration of a prior disc anomaly. None of the eyes had a posterior vitreous detachment. We could not identify any associated systemic conditions or reproduce the findings with external stimulation. Initial Snellen acuity ranged from 20/60 to 20/200. Final Snellen acuity ranged from 20/20 to 20/40. CONCLUSIONS: Fluctuating optic nerve changes may occur in the setting of atypical optic nerve coloboma and associated maculopathy. In cases of macular schisis or detachment where an optic nerve coloboma is not readily apparent, and no other causes are identified, consideration of a period of observation prior to therapeutic intervention seems appropriate.

Adult↗
PubMed1989

[An analysis of 193 cases of congenital intraocular colobomas].

In a survey of 26,512 children under 12 years of age, 2 cases (0.075%) were found to have congenital intraocular coloboma. Among 193 cases of the disease from 169 families reported by 50 hospitals of 21 provinces and cities, the disease affected boys more than girls. Bilateral colobomas of the uveal tract constituted majority of the cases, and the unilateral patients showed no predilection for either eye. The colobomas mostly occurred in the lower part of the eye, involving one or more tissues, depending on the shape, scope and location of the coloboma and whether other ocular deformities existed. Colobomas of the uvea, optic nerve and macula lutea were mostly sporadic. Earlier disruptions in the embryonal cleft resulted in more serious colobomas and complicating ocular deformities.

Adolescent↗
PubMed1997

Coloboma, mental retardation, hypogonadism, and obesity: critical review of the so-called Biemond syndrome type 2, updated nosology, and delineation of three "new" syndromes.

Biemond syndrome type 2 (BS2) is classically regarded as a recessively inherited condition (MIM 210350) comprising mental retardation, coloboma, obesity, polydactyly, hypogonadism, hydrocephalus, and facial dysostosis. Clinically, the disorder is closely related to Bardet-Biedl syndrome. Few cases have been reported, most of them before 1970. We present clinical data on three mentally retarded sporadic cases with coloboma, obesity, and hypogenitalism (in two of them), fitting as first glance a diagnosis of BS2. A review documents striking clinical variability among the patients said to have BS2. We propose a new nosology of those cases and delineate several new clinical forms. Purported BS2 cases may be divided into: (1) Bardet-Biedl syndrome with fortuitous coloboma or aniridia, (2) BS2 sensu stricto, a recessively inherited syndrome of sexual infantilism, short stature, coloboma, and preaxial polydactyly without obesity, only known from the original report, (3) a "new" dominantly inherited form of colobomatous microphthalmia occasionally associated with obesity, hypogonadism, and mental retardation, to which our observations belong. (4) cytogenetically proven Rubinstein-Taybi syndrome (one case), (5) an unclassifiable, early lethal familial syndrome resembling Buntinx-Majewski syndrome, and (6) a "new" coloboma-zygodactyly-clefting syndrome. The latter two syndromes may result from chromosomal anomaly.

Abnormalities, Multiple↗
PubMed2005

Autosomal dominant microtia and ocular coloboma: new syndrome or an extension of the oculo-auriculo-vertebral spectrum?

The oculo-auriculo-vertebral (OAV) spectrum is an etiologically heterogeneous condition classically consisting of microtia, hemifacial microsomia, epibulbar dermoids, and vertebral anomalies. Other eye findings described in OAV include upper eyelid colobomas, ptosis, and varying degrees of microphthalmia or even anophthalmia. Iris and/or retinal colobomas have rarely been reported. We describe two familial cases of apparent OAV with ocular colobomas. We postulate that iris and/or retinal colobomas associated with OAV may represent a subgroup within the OAV spectrum with autosomal dominant inheritance, as in the families described herein. Since microtia can result from aberrant migration of neural crest cells into the first and second branchial arches during early embryonic development, and concomitant deficient neural crest migration into the developing eye can lead to ocular coloboma and or iris heterochromia, it may be that the altered gene or genes in our familial cases are involved with regulation of neural crest development.

Abnormalities, Multiple↗
PubMed1993

Congenital lens coloboma and associated pathologies.

Coloboma of the lens is characterized by notching of the equator of the lens. The cause of the condition is faulty development of the zonule. The lens deprived of its normal pull in the defective region is thicker and more spherical as if there were no loss of its substance. We report five cases of lens coloboma and localized zonular defect without any associated systemic anomalies. One case included retinal detachment; another included an iris coloboma; and a third included iris, choroid and optic disk colobomas and retinal detachment with lens coloboma. The remaining two cases were without associated ocular anomalies. The pathogenic mechanisms and relationship of this defect with the differentiation of the tertiary vitreous and development of the zonule is discussed. The defect most likely occurs in the third to fourth months of gestation during differentiation of the tertiary vitreous in response to toxic, inflammatory or genetic factors.

Adolescent↗
PubMed1998

Chorioretinal colobomas in a pediatric population.

OBJECTIVE: The purpose of the study was to determine the prevalence of retinal detachment and associated anomalies in pediatric patients with chorioretinal colobomas. DESIGN: Observational case series. PARTICIPANTS: Forty-eight patients (86 eyes) of patients with chorioretinal colobomas followed in two academic pediatric eye clinics were reviewed. MAIN OUTCOME MEASURES: The frequency of associated systemic abnormalities and the prevalence of retinal or choroidal detachment during the follow-up period. RESULTS: Forty-eight patients (86 eyes) were identified; ocular involvement ranged from small colobomas with isolated chorioretinal involvement to large colobomas affecting the iris, choroid, retina, and optic nerve. The mean ages at initial and most recent examinations were 27 and 100 months, respectively. Follow-up averaged 6 years, 1 month. Six retinal detachments were found in four patients. Patient ages at the time of detection of retinal detachment were 5 months, 29 months, 10 years, and 15 years. A choroidal detachment was found in a child at age 9 years. The combined prevalence of retinal or choroidal detachment was 10.4% of patients and 8.1% of affected eyes. Thirteen eyes were microphthalmic, and six had microcornea. Eighteen patients (38%) had other systemic abnormalities. CONCLUSIONS: The 8.1% prevalence of retinal or choroidal detachment among eyes in our series was much smaller than previously cited estimates of 23% to 43%. The higher figures probably reflect a referral bias toward patients with vitreoretinal problems and an older patient population. Because of the acknowledged difficulty of managing retinal detachments in patients with chorioretinal colobomas, emphasis should be directed toward early detection and possible prophylactic therapy. The high proportion of patients who have associated systemic abnormalities indicates the need for thorough evaluation of these children by other pediatric specialists.

Adolescent↗
PubMed2000

Phacoemulsification and intraocular lens placement in eyes with cataract and congenital coloboma: visual acuity and complications.

PURPOSE: To evaluate the safety and complications of phacoemulsification in a series of patients with congenital coloboma and cataract. SETTING: University-based hospital practice. METHODS: A retrospective review was conducted of consecutive patients who had coloboma and cataract and had phacoemulsification between January 1987 through December 1998. Complications and visual acuity 2 months postoperatively were assessed. RESULTS: Mean age of 7 cases at the time of surgery was 41.6 years +/- 11.1 (SD). Visual acuity improved in 6 of 7 eyes; 1 eye had no change. Six eyes had no serious complications. In 1 eye, a retinal detachment was observed postoperatively, but there was no loss in visual acuity. Another patient developed postoperative monocular diplopia from exposure of the intraocular lens (IOL) edge within the inferonasally located corectopia associated with the coloboma. Nonsurgical treatment was unsuccessful, but this symptom resolved after surgical pupilloplasty. CONCLUSIONS: The results of this small case series affirm that clinically significant cataract develops at a younger age in eyes with congenital coloboma than in eyes with typical age-related nuclear sclerotic cataract. Monocular diplopia, a potential complication after cataract surgery in these eyes, can be managed by pupilloplasty. The improved vision in this study indicates that phacoemulsification and IOL placement are safe and beneficial in patients with typical congenital coloboma and cataract.

Adolescent↗
PubMed2005

Exclusion of LCA5 locus in a consanguineous Turkish family with macular coloboma-type LCA.

BACKGROUND: Leber's congenital amaurosis (LCA) is an inherited retinal dystrophy, which causes severe visual impairment in early childhood. Recent molecular genetic studies have linked 11 loci (AIPL1, CRB1, CRX, GUCY2D, RPE65, RDH12, RPGRIP1, TULP1, LCA3, LCA5, and LCA9) to LCA. LCA5 is a new locus, which maps to the 6q11-q16 chromosomal region and was found to be associated with macular coloboma-type LCA in a Pakistani family. Herein, we describe the molecular genetic features of a consanguineous Turkish family in which four children have macular coloboma-type LCA. METHODS: Haplotype analysis was performed on the DNA of the family members using microsatellite markers against GUCY2D, RPE65, and LCA5. Genomic DNA was screened for mutations by means of single-strand conformational polymorphism (SSCP) analysis in exons of the RPE65 and CRX genes. RESULTS: In haplotype analysis, no linkage to LCA5 or GUCY2D loci was detected. None of the tested markers showed homozygosity or segregation between affected siblings. PCR-SSCP mutation analysis revealed no mutations in the screened RPE65 and CRX genes. CONCLUSION: We excluded LCA5 as the genetic cause of macular coloboma-type LCA in this Turkish family. Macular coloboma-type LCA shows genetic heterogeneity and it is not possible to establish a phenotype-genotype correlation with LCA5 and macular coloboma.

Adolescent↗
PubMed2006

Long-term anatomical and visual outcome of vitreous surgery for retinal detachment with choroidal coloboma.

CONTEXT: Vitreous surgery has been advocated as an alternative treatment of selected retinal detachments with choroidal colobomas. AIM: To study the long term anatomical and visual outcome of choroidal coloboma with retinal detachment managed by pars plana vitrectomy with silicone oil tamponade. SETTING AND DESIGN: Retrospective study conducted in a tertiary eye care hospital. MATERIALS AND METHODS: Fourty two eyes of 40 patients with retinal detachments related to coloboma of the choroid without any peripheral breaks were analyzed. All eyes underwent pars plana vitrectomy with internal tamponade using silicone oil. Endolaser was performed along the coloboma border. Silicone oil was removed in 50% of patients. The main outcome measures were retinal reattachment and visual recovery. SPSS (Statistical Package for the Social Science), version 10.0 was used for analysis. RESULTS: The retina in all cases (100%) undergoing vitrectomy were completely reattached intra-operatively. After a mean follow-up of 14 months, 37 (88.1%) eyes had attached retina. The best corrected visual acuity was 10/200 or better in 33 (78.4%) eyes. The best corrected visual acuity improved from a preoperative median of counting fingers (range 20/40 to perception of light) to median best corrected visual acuity of 20/200 (range 20/40 to perception of light) at the end of 6 months. Of the 50% (21) cases that underwent silicone oil removal, two eyes had re-detachment of retina. CONCLUSION: Pars plana vitrectomy along with silicone oil tamponade for retinal detachment related to choroidal coloboma improves the long-term anatomical and visual outcome.

Adolescent↗
PubMed1990

Retinochoroidal coloboma: varieties of clinical presentations.

Several presentation and associated clinical problems can be seen with retinochoroidal colobomas. We review five cases of retinochoroidal coloboma with no specific clinical problems and present five cases with clinical visual impairment. The five symptomatic cases include: one with extensive bilateral involvement; one with associated rhegmatogenous detachment and peripheral tears; one with retinal detachment and apparent holes in the intercalary membrane; one with subretinal neovascularization; and a case with diabetic retinopathy, optic nerve coloboma, and peripheral retinochoroidal coloboma in one eye and a total coloboma in the other eye.

Adolescent↗