Authors: Harun Al Farhad, Ishrat Perween, Anchal Tiwari, Anjali Yadav
MBBS students, International Medical Faculty, Osh State University, Kyrgyzstan
Scientific supervisor: K. A. Raiimova, Instructor of Ophthalmology, International Medical Faculty, Osh State University
Abstract
Congenital malformations of the eye are structural defects that arise when the tightly timed sequence of ocular embryogenesis is disturbed by genetic, chromosomal or environmental causes. Individually rare, they are an important cause of childhood visual impairment and blindness, and early visual loss also alters the development of the visual cortex and of the child’s motor, cognitive and social skills. This review summarises the embryology of the eye, the classification of its malformations, and the clinical features of the main entities: the microphthalmia, anophthalmia and coloboma (MAC) spectrum, anterior segment dysgenesis (ASD), congenital cataract, persistent hyperplastic primary vitreous (PHPV) and congenital glaucoma. We discuss the genes most often involved (PAX6, SOX2, OTX2, FOXC1, PITX2, CYP1B1, CHD7 and others), the teratogens that matter in practice, and the syndromes that must be looked for in every child. Diagnostic work-up is described in a stepwise way, from the neonatal red reflex to ultrasound, MRI, anterior segment OCT and genetic testing, including recent evidence that short-read whole-genome sequencing raises the diagnostic yield in patients who remain unsolved after panel testing. Management is presented by condition, with attention to amblyopia prevention, timing of surgery, socket expansion and prosthetic rehabilitation, and multidisciplinary follow-up in line with standard paediatric practice such as that in Ghai Essential Pediatrics. We close with emerging approaches, namely stem-cell-derived optic cups, molecularly targeted therapy and improved prenatal imaging, and with the limits of what these approaches can currently offer.
Keywords: congenital ocular malformations; MAC spectrum; microphthalmia; anophthalmia; coloboma; anterior segment dysgenesis; embryology; ocular genetics; whole-genome sequencing; paediatric ophthalmology
1. Introduction
The eye begins to form in the third week of gestation and continues to grow and mature long after birth. During this period it depends on a precise exchange of signals between neuroectoderm, surface ectoderm, neural crest and mesoderm. When this exchange is disturbed by a gene variant, a chromosomal change or a teratogen, the result is a congenital ocular malformation. Because each ocular tissue has its own embryological window, the timing and type of the insult largely determine which structure is affected and how severe the defect is.
1.1 Why these malformations matter
Vision is the main sense through which an infant explores the world and bonds with parents. In the first months of life the visual cortex is highly plastic and needs clear, focused images from both eyes to wire itself correctly. A malformed, opaque or severely ametropic eye deprives it of this input, so even a structurally repairable defect can end in permanent amblyopia if it is found late. Visual impairment in infancy is also linked to delays in motor, language and social development, which is why ophthalmic care of these children cannot be separated from paediatric and developmental care.
1.2 Epidemiology
Congenital eye anomalies as a group are reported at roughly 2.4 to 7.5 per 10,000 births, with wide variation between registries and between definitions of what counts as an anomaly. Microphthalmia and anophthalmia, the most severe end of the MAC spectrum, have been estimated at about 1 in 7,000 and 1 in 30,000 births respectively. Coloboma, congenital cataract, congenital glaucoma and anterior segment dysgenesis each occur at a few cases per 100,000 to 10,000 births. Figures are higher in premature infants and in fetal and stillbirth series, and many registries under-count mild or unilateral cases.
About one third of children with microphthalmia or anophthalmia have a recognisable systemic syndrome, and many more have associated anomalies of the brain, heart, kidney, ear or skeleton. A child with an eye malformation should therefore be regarded as a child who may have a multisystem condition until proven otherwise.
1.3 Aim and scope of this review
This paper aims to give medical students and early-career clinicians a single, structured account of congenital eye malformations. It covers (1) embryology, (2) classification, (3) the main clinical entities, (4) genetic and environmental causes, (5) clinical and systemic assessment, (6) diagnosis, (7) management and prognosis, and (8) recent developments. Throughout, we link the ophthalmic findings to the paediatric context, including the neonatal red reflex examination and the multidisciplinary follow-up described in Ghai Essential Pediatrics.
2. Methodology
This is a narrative review. We searched PubMed, PubMed Central and Google Scholar for English-language papers on congenital eye malformations, using combinations of the terms microphthalmia, anophthalmia, coloboma, MAC spectrum, anterior segment dysgenesis, ocular genetics, whole-genome sequencing and congenital cataract. Priority was given to review articles, cohort studies and genomic studies published from 2023 onward, and to landmark gene-discovery and clinical-trial papers regardless of date. Foundational material on embryology and neonatal screening was taken from standard texts, including Ghai Essential Pediatrics. Papers were included when they addressed aetiology, diagnosis or management of structural ocular anomalies; case reports were used only to illustrate rare associations. Because the review is narrative and not systematic, it has no formal quality scoring, and selection bias is possible.
3. Embryology of the Eye
Eye development is a textbook case of sequential induction. Each structure forms because the one before it sends a signal, so an early error is passed on to everything that depends on it.
3.1 Tissue origins
| Embryonic source | Ocular derivatives |
|---|---|
| Neuroectoderm (optic vesicle, optic cup) | Neural retina, retinal pigment epithelium (RPE), epithelium of iris and ciliary body, iris sphincter and dilator muscles, optic nerve |
| Surface ectoderm | Lens, corneal and conjunctival epithelium, eyelid epidermis, lacrimal gland |
| Neural crest mesenchyme | Corneal stroma and endothelium, iris stroma, trabecular meshwork, ciliary muscle, most of the sclera, choroid |
| Mesoderm | Extraocular muscles, vascular endothelium, part of the sclera |
3.2 Timeline
| Stage (gestation) | Event | Possible consequence of failure |
|---|---|---|
| About day 22 | Optic sulci appear in the forebrain and form the optic vesicles | Anophthalmia, severe microphthalmia |
| Days 27 to 28 | Optic vesicle contacts surface ectoderm, which thickens into the lens placode | Aphakia, lens anomalies |
| Week 4 to 5 | Lens pit forms; optic vesicle invaginates into a double-layered optic cup | Microphthalmia, retinal dysplasia |
| Week 5 | Lens vesicle separates from the surface ectoderm | Peters anomaly, corneolenticular adhesion |
| Weeks 5 to 7 | Optic fissure closes along the underside of the cup | Coloboma of iris, retina, choroid or optic nerve |
| Weeks 6 to 8 | Neural crest cells migrate to form corneal stroma and endothelium, iris stroma and trabecular meshwork | Anterior segment dysgenesis, congenital glaucoma |
| Second trimester | Retinal layers differentiate; eyelids fuse and later reopen; optic nerve myelination begins | Retinal and optic nerve hypoplasia |
| Third trimester | The hyaloid vascular system regresses | PHPV (persistent fetal vasculature), Mittendorf dot, Bergmeister papilla |
| After birth | Axial length, lens and macula continue to mature | Amblyopia if visual input is poor |
3.3 Key steps
Optic vesicle and cup. The optic vesicle grows out from the diencephalon and meets the surface ectoderm. This contact induces the lens placode, which in turn signals back to the vesicle. The vesicle then folds in on itself to form the optic cup: the inner layer becomes neural retina and the outer layer becomes RPE. The cup remains open inferiorly as the optic (choroidal) fissure, through which the hyaloid artery enters the eye.
Lens. The placode invaginates into a pit, which pinches off in the fifth week to leave the lens vesicle. The posterior cells elongate to form the primary lens fibres, and the anterior cells remain as the lens epithelium.
Fissure closure. The edges of the optic fissure fuse between weeks 5 and 7. If they fail to meet, a cleft persists, which is a coloboma. Because the fissure runs through the iris, ciliary body, retina, choroid and optic nerve head, a coloboma can affect any or all of these.
Anterior segment. Waves of neural crest cells migrate between the lens and the surface ectoderm. They form the corneal endothelium and stroma, then the iris stroma, and they also build the trabecular meshwork and Schlemm canal that later drain aqueous humour. Faulty crest migration or differentiation underlies the whole ASD spectrum and explains the strong link between ASD and glaucoma.
Vitreous and vasculature. The primary vitreous contains the hyaloid artery. During the third trimester this system regresses, leaving the clear secondary vitreous and the Cloquet canal. Persistence of fibrovascular tissue produces PHPV, now often called persistent fetal vasculature.
3.4 Molecular control
A small group of transcription factors orchestrates these events. PAX6, SIX3 and RAX specify the eye field; SOX2 and OTX2 maintain the progenitor state and retinal identity; VSX2 and MITF separate neural retina from RPE; VAX1, VAX2and PAX2 guide closure of the optic fissure; FOXC1, PITX2 and FOXE3 direct neural crest derived tissues of the anterior segment. These genes are also dose sensitive, so loss of one copy can already produce disease, as in PAX6 aniridia.
4. Classification
Congenital ocular malformations can be grouped by the structure affected and by the stage at which development was disturbed. In practice the groups overlap, and several can occur in one patient or one family, which is why modern genetic work treats many of them as connected spectra.
| Group | Main entities | Typical embryological stage |
|---|---|---|
| MAC spectrum | Anophthalmia, microphthalmia (simple or complex, with or without cyst), coloboma | Optic vesicle and cup, optic fissure closure |
| Anterior segment dysgenesis (ASD) | Axenfeld-Rieger syndrome, Peters anomaly, aniridia, sclerocornea, posterior embryotoxon | Neural crest migration and differentiation |
| Lens anomalies | Congenital cataract, aphakia, microspherophakia, ectopia lentis | Lens placode, lens vesicle, fibre differentiation |
| Vitreoretinal anomalies | PHPV, retinal dysplasia, familial exudative vitreoretinopathy | Hyaloid regression, retinal differentiation |
| Optic nerve anomalies | Optic nerve hypoplasia, optic disc coloboma, morning glory disc | Ganglion cell axon growth, fissure closure |
| Globe size and pressure | Nanophthalmos, buphthalmos from primary congenital glaucoma | Late fetal growth, angle development |
| Adnexal anomalies | Congenital ptosis, eyelid coloboma, blepharophimosis, congenital nasolacrimal duct obstruction | Eyelid and lacrimal development |
The MAC spectrum is the clearest example of overlap. The same gene variant can cause anophthalmia in one family member, microphthalmia with coloboma in another, and an isolated iris coloboma in a third. This variable expressivity is a key reason why examining and testing relatives is part of the work-up.
5. Major Malformations in Detail
5.1 Anophthalmia and microphthalmia
Clinical anophthalmia means that no ocular tissue can be found on examination or imaging. Strictly, true absence of all ocular tissue is rare, and histology or MRI often shows small remnants, so many cases are better described as severe microphthalmia. Microphthalmia means a globe that is abnormally small for age: in an adult, an axial length more than two standard deviations below the mean, usually under about 21 mm, with corneal diameter and orbital size also reduced. In newborns the corresponding axial length is below about 16 mm.
Microphthalmia is called simple (or pure) when the eye is small but otherwise structurally normal, and complex when it is combined with other ocular anomalies such as coloboma, cataract or retinal dysplasia. Some cases have an orbital cyst, usually inferior, which may connect to the intracranial space and can enlarge over time, partly restoring orbital volume but also distorting the eyelids. The bony orbit and eyelids are usually small, and hemifacial hypoplasia may be present. Bilateral cases carry the highest risk of an underlying genetic syndrome, brain malformation and developmental delay.
5.2 Coloboma
Coloboma is a defect that results from incomplete closure of the optic fissure, so it lies in the inferonasal part of the eye in the typical form. An iris coloboma gives a keyhole or pear-shaped pupil. A chorioretinal coloboma appears as a white area of exposed sclera with absent retina and choroid, and causes a corresponding visual field defect. Disc coloboma involves the optic nerve head and may be associated with reduced acuity. Visual outcome depends mainly on whether the macula and optic nerve are involved. Complications include retinal detachment through the colobomatous area, choroidal neovascularisation, amblyopia and high refractive error. Coloboma can be isolated, but it is also the main ocular feature of CHARGE syndrome and of renal-coloboma syndrome, so systemic evaluation is always needed.
5.3 Anterior segment dysgenesis
ASD describes malformations of the cornea, iris, angle and lens that arise from disturbed neural crest development.
- Axenfeld-Rieger syndrome (autosomal dominant, usually PITX2 or FOXC1): a prominent, anteriorly displaced Schwalbe line (posterior embryotoxon), iris strands attached to it, iris hypoplasia and corectopia. Extra-ocular signs, especially with PITX2, are dental hypoplasia, redundant periumbilical skin and facial dysmorphism. About half of patients develop glaucoma, usually in childhood or early adulthood.
- Peters anomaly: a central corneal opacity with a defect in the posterior corneal layers and adhesions between iris or lens and the cornea. It is often bilateral, may be accompanied by cataract and glaucoma, and can be part of Peters-plus syndrome.
- Aniridia: partial or apparent total absence of the iris, usually from PAX6 haploinsufficiency. It is a panocular disease with foveal and optic nerve hypoplasia, nystagmus, cataract, progressive limbal stem cell failure with keratopathy, and glaucoma. When it occurs with genitourinary anomalies and intellectual disability (WAGR syndrome, 11p13 deletion including WT1), the risk of Wilms tumour requires repeated renal ultrasound.
- Sclerocornea and cornea plana: peripheral or total corneal scleralisation or a flat cornea, often with high hyperopia.
Glaucoma is the main threat to vision in ASD because the trabecular meshwork is maldeveloped. It may appear in infancy or years later, so lifelong pressure monitoring is required.
5.4 Congenital cataract
Congenital or infantile cataract accounts for a substantial share of treatable childhood blindness. It may be unilateral or bilateral, isolated or syndromic (galactosaemia, Down syndrome, Lowe syndrome, intrauterine infection), and is inherited in about a quarter to a third of cases, most often autosomal dominant. Visually significant cataract appears as leukocoria, absent red reflex, nystagmus or poor fixation. Density and position matter: a dense central opacity wider than about 3 mm in a young infant blocks the visual axis and needs prompt surgery.
5.5 Persistent hyperplastic primary vitreous / persistent fetal vasculature
PHPV results from failure of the fetal hyaloid vasculature and primary vitreous to regress. It is typically unilateral and presents with leukocoria, a small eye, a shallow anterior chamber and elongated ciliary processes seen stretched toward the centre of the lens. Cataract, retrolental fibrovascular tissue, traction on the retina and secondary angle-closure glaucoma are the usual problems. It must be separated from retinoblastoma, but unlike retinoblastoma it is usually associated with a smaller globe and the absence of calcification on imaging.
5.6 Primary congenital glaucoma
When elevated pressure acts on the elastic infant eye, the globe stretches. The classic triad is epiphora, photophobia and blepharospasm, with corneal enlargement (more than about 12 mm in the first year), Haab striae from breaks in Descemet membrane, corneal haze and optic disc cupping. It is commonly autosomal recessive and most often linked to CYP1B1. Untreated, it leads to buphthalmos and blindness, so any infant with tearing, light sensitivity and a large or hazy cornea needs urgent examination.
5.7 Optic nerve hypoplasia and other posterior anomalies
Optic nerve hypoplasia presents with poor vision, nystagmus and a small disc, sometimes with a double-ring sign. When it is accompanied by midline brain defects and pituitary dysfunction it is called septo-optic dysplasia, and hypoglycaemia, growth failure and thyroid or adrenal deficiency can be life-threatening. MRI and endocrine assessment are therefore mandatory.
6. Genetic Etiology
6.1 Overview
Most congenital eye malformations have a genetic component, but the picture is heterogeneous. Pathogenic variants in single genes explain a large share of severe bilateral cases, whereas unilateral and mild cases are more often sporadic, multifactorial or caused by mosaic or non-coding variants that routine tests miss. Inheritance may be autosomal dominant (often de novo), autosomal recessive, X-linked or chromosomal. Reduced penetrance and variable expressivity are common, so a parent with a subtle coloboma may have a child with anophthalmia.
6.2 Principal genes
| Gene | Main ocular phenotype | Inheritance | Important associations |
|---|---|---|---|
| PAX6 | Aniridia, Peters anomaly, foveal hypoplasia, cataract, microphthalmia | AD (haploinsufficiency) | WAGR with 11p13 deletion (Wilms tumour); brain anomalies with severe alleles |
| SOX2 | Bilateral anophthalmia or microphthalmia | AD, usually de novo | Hypopituitarism, brain malformation, oesophageal atresia, hearing loss, genital anomalies |
| OTX2 | Anophthalmia, microphthalmia, retinal dystrophy | AD | Pituitary hormone deficiency, brain malformation, developmental delay |
| CHD7 | Coloboma | AD | CHARGE syndrome: heart, choanal atresia, growth, genital and ear anomalies |
| PAX2 | Optic nerve coloboma and dysplasia | AD | Renal hypoplasia (renal-coloboma syndrome) |
| BMP4 | Microphthalmia, anophthalmia, coloboma | AD | Brain and digital anomalies, hypoplastic kidney |
| STRA6, RBP4 | Anophthalmia, microphthalmia | AR (STRA6), AD (RBP4) | Vitamin A transport; cardiac and diaphragmatic defects |
| VSX2 | Isolated microphthalmia | AR | Usually no systemic features |
| FOXC1 | Axenfeld-Rieger, Peters anomaly | AD | Glaucoma; cardiac defects, hearing loss; 6p25 deletions |
| PITX2 | Axenfeld-Rieger | AD | Dental hypoplasia, redundant periumbilical skin |
| FOXE3 | Aphakia, sclerocornea, Peters anomaly | AR, AD | Microphthalmia |
| CYP1B1 | Primary congenital glaucoma; Peters anomaly | AR | Most common gene in primary congenital glaucoma in many populations |
| BCOR | Microphthalmia, cataract | X-linked | Oculofaciocardiodental and Lenz microphthalmia syndromes |
PAX6 is often called the master regulator of eye development, and its dosage is critical: one working copy causes aniridia, while loss of both is generally incompatible with eye formation. SOX2 and OTX2 are required early for retinal progenitors, and their disruption explains why anophthalmia is so often accompanied by pituitary and brain anomalies. CHD7 and PAX2 connect coloboma to the heart, ear and kidney.
6.3 Syndromes to recognise
Syndromes in which MAC or ASD occurs include CHARGE syndrome, Aicardi syndrome, Lenz microphthalmia, Fraser syndrome, Goldenhar spectrum, Gorlin syndrome, Walker-Warburg syndrome, Peters-plus syndrome, Down syndrome and trisomy 13. Chromosomal rearrangements involving 3q26 (the SOX2 region), 14q22 (OTX2), 11p13 (PAX6 and WT1) and 6p25 (FOXC1) are also described. Typical features that point to a syndrome are intellectual disability, microcephaly, facial clefting, ear anomalies, congenital heart disease, renal anomalies, limb anomalies (polydactyly, clinodactyly) and growth failure.
6.4 From panels to genomes
Historically, the diagnostic yield in eye malformations has been limited. Single-gene tests and microarrays solve a fraction of cases, and even with targeted gene panels fewer than half of affected individuals receive a molecular diagnosis. A Japanese cohort recruited in 2024 and 2025 of 111 patients (102 families) with bilateral ASD, aniridia, microphthalmia or anophthalmia, tested with custom panels, reached diagnostic rates of 50.0% for ASD or aniridia and 37.5% for microphthalmia or anophthalmia, showing both the usefulness and the limits of panels.
Whole-genome sequencing (WGS) addresses part of this gap because it detects structural variants, copy-number changes and variants in non-coding regulatory regions as well as coding variants. In a study from the Edinburgh MRC Human Genetics Unit, short-read WGS was applied to 51 individuals (39 affected) from 37 families with aniridia whose PAX6coding region was normal, and it identified causative variants in most of them, including deletions and other changes that coding-sequence testing had missed. A recent French study (AURAGEN), which applied short-read WGS to 100 families with microphthalmia-anophthalmia, coloboma, ASD, congenital cataract or foveal hypoplasia, concluded that WGS significantly improves the diagnostic yield, including in patients who had remained undiagnosed after panel testing. These findings support a stepwise strategy of panel or exome first, then genome, when the phenotype is strong and the first test is negative.
A molecular diagnosis matters because it shapes counselling about recurrence risk, directs screening for associated disorders (for example, renal ultrasound in PAX6 deletions or endocrine evaluation in SOX2 and OTX2 disease), may predict visual prognosis, and allows entry into research and future trials.
7. Environmental and Teratogenic Factors
In a large share of patients no genetic cause is found, and environmental influences, often acting during the first trimester, are suspected. A 2024 scoping review noted that a clear aetiology is not identified in most patients with congenital eye anomalies, and that several prenatal medications are known to disturb eye morphogenesis.
| Factor | Ocular consequences | Practical point |
|---|---|---|
| Congenital rubella | Cataract (often dense, bilateral), microphthalmia, salt-and-pepper retinopathy, glaucoma | Preventable by MMR vaccination before pregnancy |
| Congenital CMV and toxoplasmosis | Chorioretinitis, optic atrophy, microphthalmia, cataract | Part of the TORCH work-up for a leukocoric or microphthalmic neonate |
| Herpes simplex and varicella | Chorioretinal scarring, cataract, microphthalmia | Early maternal antiviral treatment |
| Alcohol (fetal alcohol spectrum) | Optic nerve hypoplasia, small palpebral fissures, ptosis, refractive error | No safe level during pregnancy |
| Vitamin A excess or deficiency | Excess (retinoids such as isotretinoin) can cause microphthalmia; deficiency is linked to anophthalmia and coloboma | Retinoic acid signalling is central to optic cup formation |
| Thalidomide | Anophthalmia, microphthalmia, coloboma | Historical teratogen, shows the critical window |
| Warfarin, some antiepileptics (valproate, phenytoin), mycophenolate, misoprostol | Eye and craniofacial anomalies | Review all medicines at preconception counselling |
| Maternal diabetes | Higher risk of microphthalmia and coloboma | Optimise glycaemic control before conception |
| Maternal smoking, ionising radiation, drugs of abuse | Nonspecific increase in anomalies | Counselling and avoidance |
The general principle is that the earlier the exposure in the first trimester, the more severe the malformation, and the later the insult, the more subtle the defect. Vitamin A needs special mention because both too little and too much are harmful, so supplementation should follow recommended doses.
8. Clinical Presentation and Systemic Evaluation
8.1 How these children present
Severe anophthalmia or microphthalmia is obvious at birth: a small or absent palpebral fissure, a sunken or empty-looking socket, a small orbit and sometimes ptosis or hemifacial asymmetry. Milder malformations are discovered by a parent noticing an unusual pupil, white reflex or large cloudy eye, or by a clinician at routine screening. The main presenting signs are:
- Leukocoria (white pupillary reflex or absent red reflex): cataract, PHPV, coloboma, retinal detachment, Coats disease, retinopathy of prematurity, toxocariasis and, most urgently, retinoblastoma.
- Abnormal pupil or iris: keyhole pupil, corectopia, aniridia.
- Corneal opacity or enlarged cornea: Peters anomaly, sclerocornea, congenital glaucoma, birth trauma, metabolic storage disease.
- Tearing, photophobia and blepharospasm: congenital glaucoma (and, more commonly, nasolacrimal duct obstruction).
- Nystagmus: pendular, roving or searching movements usually mean severe bilateral visual loss before about 2 to 3 months of age, as in aniridia, optic nerve hypoplasia, and bilateral cataract.
- Strabismus and poor fixation or following: deprivation or sensory strabismus, amblyopia.
Any leukocoria in an infant is an emergency until retinoblastoma has been excluded by a dilated fundus examination, with ultrasound or MRI as needed.
8.2 Systemic evaluation
Because many malformations are syndromic, every child needs a whole-body assessment rather than an eye examination alone.
- History: pregnancy (infections, drugs, alcohol, diabetes, vitamin A exposure), gestational age, birth weight, neonatal course, feeding, hearing and developmental milestones.
- Three-generation family history and examination of parents and siblings, looking for subtle coloboma, iris anomalies, cataract, early glaucoma and consanguinity.
- Dysmorphology examination: head circumference, facial clefts, ear shape, choanal patency, limbs, skin, genitalia, growth parameters.
- Organ screening: echocardiography (CHARGE, BMP4, STRA6), renal ultrasound (PAX2, WAGR, CHARGE), audiology, and endocrine tests when there is hypoglycaemia, poor growth or optic nerve hypoplasia.
- Neurological assessment and neuroimaging for developmental delay, seizures, microcephaly or midline defects.
- Genetic referral, ideally before the family leaves the hospital after birth, so that testing and counselling occur together.
9. Diagnostic Approach
The aim is to establish what is wrong, whether it is isolated or syndromic, and how much visual potential can be saved. Diagnosis is made in steps, starting with simple bedside tests that every paediatrician can do.
9.1 Screening in the newborn and infant
The red reflex test is the key screening test. It is done in a dim room with a direct ophthalmoscope held about 20 to 30 cm from the child, and it should be performed in the newborn period and repeated at every well-child visit. A dull, white, asymmetric or absent reflex, or a reflex that differs between the two eyes, needs urgent referral. The corneal light reflex (Hirschberg), fixation and following, and pupil responses should also be recorded. Ghai Essential Pediatrics emphasises that routine neonatal examination of the eyes, including the red reflex, is how most treatable congenital eye disease is picked up before amblyopia sets in.
9.2 Ophthalmic examination
- Visual function: fixation preference, preferential looking, visual evoked potentials and electroretinography when the history suggests retinal or optic nerve disease.
- Anterior segment: handheld slit lamp for cornea, iris, pupil and lens. Corneal diameter and intraocular pressure are measured, preferably with a rebound or handheld applanation tonometer, and gonioscopy is used to assess the angle.
- Fundus: dilated indirect ophthalmoscopy. Cycloplegic refraction detects high ametropia that could cause amblyopia.
- Examination under anaesthesia (EUA): often needed in infants for accurate pressure, gonioscopy, corneal diameter, axial length and fundus examination.
9.3 Imaging
| Modality | Use | Main limitation |
|---|---|---|
| B-scan ultrasound | Axial length, globe shape, orbital cyst, retinal detachment, retrolental mass when media are opaque | Operator dependent; limited soft tissue detail |
| Ultrasound biomicroscopy (UBM) | Angle, ciliary body, iris and lens relationships in ASD, Peters anomaly, PHPV | Small field; needs cooperation or sedation |
| Anterior segment OCT | Non-contact cross-section of the cornea, angle and iris; corneal thickness | Corneal opacity limits depth; infants may need handheld devices |
| MRI of orbit and brain | Globe volume, optic nerve and chiasm, extraocular muscles, orbital cysts, brain and pituitary malformations (for example with OTX2, SOX2 or septo-optic dysplasia) | Needs sedation in infants; cost |
| CT | Bony orbit, calcification when retinoblastoma is suspected | Radiation; MRI is preferred in children |
| Fetal ultrasound and fetal MRI | Prenatal detection of anophthalmia, severe microphthalmia, cysts and brain anomalies | Mild defects are usually missed |
9.4 Laboratory and genetic testing
Investigations are chosen according to the phenotype: TORCH serology and urine or blood CMV PCR for suspected intrauterine infection, galactose-1-phosphate uridyltransferase testing and urine reducing substances for cataract, and a metabolic screen when systemic disease is suspected. Genetic testing generally proceeds from chromosomal microarray to a targeted gene panel or exome, and to genome sequencing in unsolved cases, together with pre- and post-test counselling. The results should be interpreted together with the clinical features, since a variant of uncertain significance does not establish a diagnosis.
9.5 Differential diagnosis checkpoints
The clinician should always ask: is this retinoblastoma? is the intraocular pressure raised? is there a systemic syndrome or an infection that is still treatable? is the other eye normal, and will it be at risk of amblyopia or trauma? Answering these four questions guides the speed and sequence of investigations.
10. Management and Prognosis
10.1 Principles
Treatment is a long-term partnership of the family with a pediatric ophthalmologist, paediatrician, clinical geneticist, ocularist or oculoplastic surgeon, orthoptist, optometrist, low-vision specialist and, where indicated, endocrinologist, cardiologist, nephrologist, audiologist and developmental therapist. Management has three goals: save and develop whatever vision is possible, treat associated systemic disease, and support the child’s growth, learning and participation. Following the child-centred approach of Ghai Essential Pediatrics, ocular treatment is planned together with nutrition, immunisation, developmental surveillance and family support.
10.2 Management by condition
| Condition | Main treatment | Timing and notes |
|---|---|---|
| Congenital cataract (visually significant) | Lens aspiration with posterior capsulotomy and anterior vitrectomy; then optical correction by contact lens or intraocular lens (IOL) | Unilateral: ideally by about 6 weeks of age. Bilateral: ideally by about 6 to 8 weeks, with the second eye soon after. IOL use below age 1 to 2 years is debated because of a higher rate of complications |
| Primary congenital glaucoma | Goniotomy or trabeculotomy (clear cornea), trabeculectomy or tube shunt if these fail; medical therapy as a bridge | Urgent; early surgery protects the optic nerve. Lifelong follow-up |
| Glaucoma in ASD | Medication first, then angle or filtration surgery | Often more difficult than primary congenital glaucoma; needs frequent monitoring |
| Coloboma | Refraction, amblyopia therapy, protective eyewear, cosmetic or tinted lenses for iris defects | Examine the retina regularly for detachment |
| Aniridia | Tinted or iris-print lenses, sun protection, lubricants, management of keratopathy, glaucoma and cataract | Screen for Wilms tumour when a WT1 deletion is present |
| Peters anomaly and corneal opacity | Dilatation when the lens is clear, optical iridectomy, or keratoplasty in selected cases | Graft outcomes in infants are guarded and need intense follow-up |
| PHPV / persistent fetal vasculature | Surgery (lensectomy and vitrectomy) in selected cases, followed by amblyopia treatment | Visual outcomes are often limited by retinal and optic nerve findings |
| Anophthalmia and severe microphthalmia | Early conformers or expanders to enlarge the socket and orbit, later a custom prosthesis | Start in infancy while orbital bone growth is most rapid |
10.3 Amblyopia and visual rehabilitation
Amblyopia is the most preventable cause of visual loss in these children. The steps are early correction of significant refractive errors, spectacles or contact lenses after cataract surgery, and occlusion (patching) or atropine penalisation of the better-seeing eye in unilateral disease. Treatment must be started promptly because the sensitive period for cortical plasticity is longest in early infancy, but it still has value in later childhood. For children with bilateral severe loss, early intervention services, orientation and mobility training, tactile and auditory learning strategies, low-vision devices and school support are as important as any operation.
10.4 Socket and orbital expansion
In anophthalmia and severe microphthalmia the orbit grows in proportion to the volume it contains, so an empty or very small socket leads to a small orbit and facial asymmetry. Treatment therefore starts in the first weeks of life with progressively larger conformers or hydrogel expanders, which stimulate growth of the orbit and eyelids. As the child grows, a custom-made prosthesis improves appearance and eyelid function. When an orbital cyst is present, aspiration or excision may be needed. Psychological support for parents and, later, for the child, is part of this process.
10.5 Prognosis
Prognosis ranges from near-normal vision in a small iris coloboma to profound blindness in bilateral anophthalmia. It depends on the structures involved, the presence of glaucoma or retinal detachment, the age at diagnosis and surgery, how well amblyopia is treated, and whether there are neurological or other systemic problems. Because many of these conditions are lifelong, follow-up includes transition from paediatric to adult services.
11. Recent Advances
11.1 Genomic diagnosis
The most practical advance has been the growing use of genome sequencing. As described in section 6.4, short-read WGS has resolved families with aniridia whose coding sequencing was normal and has raised diagnostic yield in a 100-family cohort with a range of developmental eye disorders. Panel studies in new populations, such as the Japanese cohort of 111 patients, add to the catalogue of variants and show that diagnostic rates remain well below 100%, so unsolved patients will benefit from re-analysis and from newer approaches such as long-read sequencing and optical genome mapping.
11.2 Prenatal imaging and counselling
High-resolution fetal ultrasound and fetal MRI can identify severe microphthalmia, anophthalmia, orbital cysts and associated brain anomalies in the second trimester. This allows genetic counselling, a plan for delivery in a centre with neonatal and ophthalmic expertise, and early referral for socket expansion. Mild malformations, such as small colobomas, are usually not visible before birth.
11.3 Stem cell and organoid models
Human pluripotent stem cells can be guided to self-organise into three-dimensional optic-cup-like structures with stratified neural retina. These organoids allow researchers to study the effect of PAX6, SOX2 and OTX2 variants in human tissue and to screen candidate drugs, and are an early step toward cell-replacement therapy for retinal and RPE disease. Replacement of tissues damaged in utero, such as the corneal endothelium in Peters anomaly, remains a long-term goal and is not yet clinical practice.
11.4 Targeted and molecular therapies
Because eye structures are formed before birth, treatment that corrects a malformation is difficult. Still, some conditions have a postnatal window. In mouse models, adjusting Pax6 dosage after birth reversed part of the corneal and lens abnormalities, and read-through drugs have been explored for aniridia caused by nonsense variants in PAX6. Gene therapy is already approved for an inherited retinal dystrophy (RPE65-related disease), which shows the principle, but it has not been applied to structural malformations in routine practice. Such therapies should be described to families as research, not as available treatment.
11.5 Surgical and optical progress
Safer paediatric cataract techniques, better IOL options, long-term outcome data from randomised trials of contact lens and IOL correction in infants, minimally invasive glaucoma procedures, handheld OCT and teleophthalmology screening in neonatal units have improved access and results, especially where specialist services are limited.
12. Discussion and Conclusion
12.1 Discussion
Congenital eye malformations sit at the crossroads of embryology, genetics and paediatric care. The timing of the insult determines the phenotype, the gene involved determines the associated systemic risks, and the age at which the child is diagnosed determines how much vision can be preserved. These three layers explain why the same defect can mean very different things for different children.
The central clinical challenge is the narrow window of visual development in infancy. A cataract or glaucoma that is recognised late may be surgically perfect and still leave permanent amblyopia. The red reflex examination at birth and at each well-child visit, taught in standard paediatric texts such as Ghai Essential Pediatrics, remains the simplest and most effective safeguard, and it costs almost nothing.
The second challenge is heterogeneity. Hundreds of genes can disturb eye development, and a large proportion of patients still lack a molecular diagnosis. Genome sequencing is narrowing this gap, but it also brings variants of uncertain significance, cost, and a need for expert interpretation and counselling. A genetic result should always be read alongside a careful clinical assessment.
The third challenge is the whole child. Many malformations belong to syndromes with cardiac, renal, endocrine, hearing and neurological involvement, some of them life-threatening, such as hypoglycaemia in septo-optic dysplasia or Wilms tumour in WAGR syndrome. An ophthalmic diagnosis should therefore always trigger a systemic assessment.
12.2 Limitations of this review
This is a narrative review with a limited number of recent primary studies, so it cannot give pooled estimates of prevalence, diagnostic yield or treatment outcome. Epidemiological figures vary between registries. Emerging therapies described here are mostly experimental. Readers should consult current guidelines and specialist centres for clinical decisions.
12.3 Conclusion
Early recognition, a structured systemic and genetic work-up, timely surgery, vigorous amblyopia prevention and coordinated multidisciplinary follow-up are the foundation of care for children with congenital eye malformations. Advances in genome sequencing, prenatal imaging and stem-cell research are improving diagnosis and understanding, and may in time add targeted treatments. Until then, universal red reflex screening, prompt referral and family-centred support remain the most effective ways to protect these children’s vision and development.
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