Childhood vision and hearing disorders

• The red reflex test is the single most important screen in the first months of life: an abnormal reflex (white, yellow, dull or asymmetric) must be treated as urgent, because retinoblastoma and congenital cataract hide behind it. ^[5]
• A child vision screening programme is offered at 4 to 5 years in the UK to find amblyopia while the visual system is still plastic; the USPSTF recommends screening children aged 3 to 5 years to detect amblyopia or its risk factors. ^[1][4]
• Strabismus does not resolve after 4 months of age; any constant squint in an older infant needs referral, and any leukocoria needs urgent eye clinic referral. ^[5][8]
• Amblyopia is a developmental disorder of the visual cortex, not simply a lazy eye: treating the underlying cause (spectacles, patching, atropine penalisation) before about 7 years gives the best, and sometimes the only, chance of normal vision. ^[5]
• Retinoblastoma is the most common intraocular cancer of childhood (about 1 in 15,000 to 20,000 live births): presenting most often as leukocoria, it is curable, but mortality is high where diagnosis is delayed. ^[6]
• Newborn hearing screening aims to find permanent moderate, severe or profound deafness (about 1 to 2 in 1,000 babies; 1 in 100 after more than 48 hours of neonatal intensive care) so that treatment and support begin within the first months of life. ^[3]

By the end of this topic you should be able to:

1. Perform and interpret the red reflex test in an infant and state the correct response to an abnormal result.
2. Outline a developmentally appropriate visual assessment from birth to age 5 and state UK and US screening ages.
3. Recognise strabismus, distinguish it from pseudostrabismus, and list the red flags that demand urgent referral.
4. Define amblyopia, classify it by cause, and plan first-line treatment with optical correction, patching or atropine.
5. Describe the presentation, genetics and staging principles of retinoblastoma, and name the main treatments.
6. Explain the objectives, tests and timetable of newborn hearing screening, and state the 1-3-6 intervention principle.
7. Distinguish conductive from sensorineural hearing loss, list common causes of each, and outline low-resource management. ^[7]

Vision and hearing are the two senses through which a young child learns, relates and communicates. A defect in either is easily missed by the child and by the parents, because a child with poor sight in one eye still plays and reads with the other, and a deaf baby may still startle to loud sounds. The role of paediatric screening is to find these problems before the brain has finished wiring itself, during the neuroplastic windows in which treatment actually works.

This topic covers the paediatric visual system (the red reflex, strabismus, amblyopia and retinoblastoma) and childhood hearing (newborn hearing screening, then conductive, sensorineural and mixed hearing loss). It draws on UK screening guidance, US professional bodies (AAPOS, AAO and AAP), WHO and CDC material, plus a recent comprehensive review of retinoblastoma management. Guidelines differ in detail by country, so wherever a programme, age or threshold is named below it is attributed to the body that set it. ^[7]

In a darkened room the examiner sets a direct ophthalmoscope to zero, stands at arm's length from the child and looks at both pupils at once while the child looks at the light. The light that returns from the retina gives the familiar orange-red glow. Performed on both eyes together, this is the Bruckner (binocular red reflex) test.^[5]

A normal red reflex is symmetric in colour, brightness and size. It is a screening test, not a diagnosis: it is quick and needs no drops, but the clinician must learn what normal looks like in lightly versus darkly pigmented eyes, because normal pigment varies by race and ethnicity.^[5]

The test asks one question: is anything blocking or distorting the light path from cornea to retina? An asymmetric or dull reflex can also be the only sign of strabismus or of a significant refractive error.^[5]

A red reflex is abnormal when it is absent, dull, white or yellow (leukocoria), or different between the two eyes. Any of these should prompt referral for a full ophthalmic examination, including cycloplegic refraction and dilated fundus examination, in cooperation or under sedation or anaesthesia when needed.^[5]

High-risk infants need assessment by an ophthalmologist rather than screening alone: those born very preterm or with ROP risk, and any infant with a family history of retinoblastoma, congenital cataract or glaucoma, retinal dystrophy, systemic disease or neurodevelopmental delay associated with eye problems, opacity of the ocular media, or nystagmus.^[4]

The commonest benign trap is pseudostrabismus: prominent epicanthal folds can make a baby's eyes look crossed when alignment is normal. In the neonatal period, intermittent strabismus is also normal. Constant horizontal strabismus that persists beyond 4 months of age does not resolve spontaneously and must be referred.^[5]

Strabismus is a misalignment of the eyes. It is usually isolated in children, but because it can be the first sign of intracranial, intraorbital or intraocular disease, the cause must be considered rather than assuming a benign childhood squint. It occurs at any age, and its development in later childhood rather than infancy is itself a clue.^[8]

The strabismus most relevant to amblyopia is a constant esotropia (inward turn), which the immature brain cannot fuse: the image in the turning eye is suppressed and, if the suppression persists, the development of vision in that eye is arrested. Intermittent and alternating squints carry less risk. Strabismus is also what brings many children with retinoblastoma to attention, because a tumour involving the fovea can disturb eye movement or fixing behaviour.

Most childhood squints are benign and can go to the local children's eye service on a routine basis. Refer urgently (within days) to paediatric ophthalmology or the appropriate specialist if any red flag is present: new-onset or acute squint; double vision; headache, behavioural change or milestone regression; ataxia or nystagmus; an abnormal red reflex; or leukocoria.^[8] Moorfields Eye Hospital guidance refers a child with an abnormal red reflex within 2 weeks to the acute eye clinic.^[8]

The examination in primary care is simple and should be done before referring: inspect the eyes, look for ptosis and epicanthal folds, perform the corneal light reflex test (asymmetry of the reflex points to a turn), and do a cover test. Red reflex testing should be done before referral, especially in children aged 7 years or under, and any neurological concerns or developmental delay must be recorded because they change the urgency of the referral.^[8]

The management is set by the paediatric eye service, not by primary care: correct any significant refractive error (glasses often fully correct an accommodative esotropia), treat amblyopia with occlusion or penalisation if it is present, and correct residual misalignment surgically when needed. Botulinum toxin injection into an extraocular muscle is used in selected circumstances.^[8]

Occlusion with a patch usually produces a quicker response than atropine, which has traditionally been reserved for poor compliance with patching; penalisation may be easier in school-age children. The patch is worn part-time, with the daily hours set by age and severity. Surgery may reduce rather than fully eliminate the turn, and some children need more than one operation.^[8]

Amblyopia is a unilateral, or less often bilateral, reduction in best-corrected visual acuity in an eye that is structurally normal. It is a developmental disorder of the central nervous system, produced by abnormal processing of visual images in early life. The fellow eye is often not quite normal either. By most definitions amblyopia is permanent if it is not treated in childhood: the visual loss is lifelong and can be profound.^[5]

Amblyopia meets the WHO criteria for a condition worth screening for: it is common, its treatment is established, it has a latent stage, and it can be detected before permanent loss occurs.^[5]

Prevalence in population-based studies of children aged 30 to 71 months ranges from 0.7% to 2.6%; school-based studies of older children usually report higher rates, from 1.0% to 5.5%, depending on age, ethnicity and definition. It usually affects one eye, though 5% to 41% of cases are bilateral depending on criteria. Unilateral amblyopia is associated with strabismus in 19% to 50% of cases and with refractive error in 46% to 79% of cases.^[5]

• Refractive: anisometropic (unequal focusing between eyes) or high bilateral (isoametropic). Greater anisometropia and higher astigmatism raise both risk and severity.^[5]
• Strabismic: a constant, non-alternating deviation; esodeviations predominate. Competitive inhibition between the inputs of the two eyes suppresses the deviated eye.
• Visual deprivation: obstruction of the visual axis, such as congenital cataract, corneal opacity, ptosis, or vitreous haemorrhage. This is the least common form but often the most severe. A visually threatening unilateral cataract has the best prognosis if surgery and optical correction are complete by 2 months of age.^[5]
• Occlusion (reverse) amblyopia: deprivation caused by the treatment itself, such as patching; in practice this is uncommon and usually resolves when treatment stops.^[5]

Amblyopia is a clinical diagnosis of a VA deficit in the presence of one of the above causes; it should never be accepted without looking for an organic lesion. Diagnostic visual acuity thresholds are roughly 2 or more lines of difference between the eyes in unilateral disease, and in bilateral disease vision under 20/50 at age 3 to under 4 years, under 20/40 at 4 to under 5 years, and under 20/30 at 5 years or older, each in the presence of an amblyogenic factor.^[5]

The red reflex test described above is therefore part of every amblyopia work-up, because an organic cause must be excluded first. The examination should include cycloplegic refraction, assessment of binocular alignment and movement, pupil examination, external inspection and a fundus examination (often under anaesthesia in young children). Visual acuity is measured formally once the child cooperates, using age-appropriate optotypes presented in a full line rather than singly, because single optotypes overestimate acuity in amblyopia through the crowding phenomenon.^[5]

Screening and early detection matter because younger age at treatment gives a better visual outcome: three-quarters of children under 7 years with moderate strabismic or anisometropic amblyopia reached VA 20/30 or better six months after starting treatment.^[5]

Management is directed at the amblyopia service and includes three steps: remove any visual axis opacity, correct refractive error, and force use of the amblyopic eye by reducing vision in the fellow eye.

1. Optical correction. Refractive correction alone is the first step for children aged 0 to 17 years and often produces immediate improvement. Continued wear for 18 weeks improves VA by 2 or more lines in at least two-thirds of children aged 3 to 7 years with untreated anisometropic amblyopia.^[5]
2. Patching. Part-time occlusion of the better eye is appropriate when VA has not improved enough with spectacles. Most children with moderate amblyopia (20/40 to 20/80) respond to an initial regimen of 2 hours of daily patching or atropine on weekend days. The daily hours are set by age and severity.^[5]
3. Atropine penalisation. Blurring the sound eye with atropine drops forces use of the amblyopic eye; it is traditionally reserved for poor compliance with patching, and is a useful option in school-aged children. Reverse amblyopia is possible (reported in about 1% with heavy patching and 9% with daily atropine in older trials) but usually resolves when treatment is paused.^[5]
4. Other modalities. Translucent Bangerter (fogging) filters, optical treatment (over-plus lenses, which blur the good eye), dichoptic digital therapy, and surgery for deprivation causes are all used, chosen to the child's age, VA, adherence and psychological state.^[5]
5. Follow-up. Treatment is adjusted when there is no change after about 3 months: maintain or increase patching or atropine, or try an alternative. Monitoring is continued after improvement because relapse is common, and additional treatment maintains the gain.^[5]

Treatment can help in older children and adolescents, particularly if they have not been treated before, although success rates fall with age; timeliness is the key determinant of outcome.^[5]

Early detection through the screening programmes above, prompt correction of refractive error and strabismus, and referral of any child with risk factors (prematurity, birth weight under 1,500 g, developmental delay, cerebral palsy, syndromes with ocular involvement such as Down syndrome, and a family history of amblyopia, strabismus, childhood cataract or glaucoma) all reduce amblyopia. Lifetime risk of bilateral visual impairment is approximately doubled in untreated amblyopia.^[5]

Retinoblastoma is the most common primary intraocular cancer of childhood and comprises about 2.5% to 4% of all paediatric malignancy. Incidence is roughly constant worldwide at 1 case per 15,000 to 20,000 live births; prevalence of disease is higher in Asia and Africa because of higher birth rates, not higher biological risk. Two-thirds of cases are diagnosed by age 2 years and 95% by age 5.^[6]

It is caused by biallelic inactivation of the RB1 tumour suppressor gene on chromosome 13q14, which removes the brake on the G1 to S phase transition. The traditional two-hit hypothesis still underpins the clinical subtypes:

• Heritable (germline) tumours make up 30% to 40% of cases. The first hit is in every cell; these tumours are often bilateral (80%), multifocal, and present earlier. About 75% of germline mutations are new (de novo) rather than inherited; familial transmission is autosomal dominant with about 90% penetrance. Heritable disease also confers a lifelong risk of secondary cancers (osteosarcoma, leiomyosarcoma, melanoma), especially after external beam radiotherapy.^[6]
• Non-heritable tumours are 60% to 70% of cases: both hits occur in a single retinal cell, producing unilateral, usually unifocal disease presenting later, in the second to third year. A small minority of unilateral, non-heritable tumours are driven by MYCN amplification rather than RB1 loss.^[6]
• 13q deletion syndrome produces additional dysmorphic features and neurodevelopmental delay.^[6]

Unilateral disease should not be assumed somatic: 10% to 15% of unilateral cases may carry a germline RB1 mutation, and bilateral disease is always heritable. Genetic testing is ideally indicated in every child whose RB1 status is unknown. Penetrance is 90%, so 10% of mutation carriers never develop a tumour.^[6]

Leukocoria (a white pupillary reflex, often first noticed in flash photographs) is the most common presentation, seen in 60% to 80% of cases. Strabismus is the next most common and implies foveal involvement by the tumour. In low- and middle-income countries, presentation is often later, with proptosis, buphthalmos, a painful red eye from secondary glaucoma, or orbital cellulitis-like change.^[6]

Diagnosis is clinical and must never be confirmed by biopsy, because puncturing the tumour risks seeding. Examination under anaesthesia is essential for diagnosis and staging: indirect ophthalmoscopy with scleral indentation, inspection of seed morphology (dust, clouds, pearls), and measurement of tumour dimensions. MRI with a high-resolution orbital and brain protocol is used to detect extraocular extension, optic nerve invasion and pineoblastoma; ultrasound B-scan detects the pathognomonic calcification. CT is best avoided because of radiation risk in heritable disease.^[6]

Staging systems include the International Classification of Retinoblastoma (groups A to E, based on predicted response to systemic chemotherapy) and the AJCC TNMH staging (8th edition), which incorporates tumour extent, nodal and distant spread and, uniquely, heritable status (H0 versus H1). Group A eyes are small intraretinal tumours; group E eyes are anatomically destroyed. The common differential diagnoses of leukocoria include Coats disease, persistent fetal vasculature, congenital cataract, ocular toxocariasis, retinopathy of prematurity and retinal detachment.^[6]

The aims of treatment, in order, are survival, then globe salvage, then visual preservation. The choice depends on stage, laterality, germline status, visual potential and family and institutional circumstances.

• Enucleation remains the definitive treatment for advanced, massive or high-risk unilateral disease and when a tumour involves the optic nerve.
• Intravenous chemotherapy, most commonly the triple-drug VEC (vincristine, etoposide, carboplatin) chemoreduction regimen, is used for bilateral disease, germline tumours, positive family history and high-risk histology, with excellent salvage rates of 90% to 100% for group A to C tumours. Standard doses are vincristine 1.5 mg per m2 (0.05 mg per kg if under 3 years), etoposide 150 mg per m2 (5 mg per kg if under 3 years) and carboplatin 560 mg per m2 (18.6 mg per kg if under 3 years). Adjuvant chemotherapy after high-risk pathology reduces metastatic risk markedly.^[6]
• Intra-arterial chemotherapy (IAC), delivering melphalan (commonly 5 mg over 30 minutes monthly for three cycles for groups B and C), with or without topotecan, through the ophthalmic artery, is the standard of care for eye salvage in many high-income countries and is particularly used for unilateral non-germline group B to E tumours. Globe salvage reaches about 100% for groups B and C, 94% for D and 36% for E. It is contraindicated with extraocular spread, orbital cellulitis, neovascular glaucoma, pineoblastoma or metastasis, and is technically difficult under 4 months of age.^[6]
• Focal consolidation: transpupillary thermotherapy, cryotherapy and laser photocoagulation (plaque brachytherapy for selected medium tumours).
• Intravitreal chemotherapy (melphalan or topotecan) for recalcitrant vitreous seeds, and intracameral chemotherapy for anterior chamber seeding, both usually ancillary rather than stand-alone.
• External beam radiotherapy is now reserved for residual or metastatic disease because of the high lifetime risk of secondary malignancies in heritable disease.
• Metastatic or extraocular disease retains a poor prognosis despite neoadjuvant and adjuvant regimens.^[6]

Low- and middle-income settings bear a disproportionate burden: delayed presentation with advanced disease limits globe-salvage options, and mortality ranges from 20% to 40% in Latin America and Asia (excluding Japan) to 70% in Africa, compared with 3% to 5% in Japan, North America and Europe. Early recognition of leukocoria in primary care, rapid referral and genetic counselling are therefore the interventions with the largest impact.^[6]

Complications arise from the tumour (retinal detachment, glaucoma, orbital invasion, metastasis to the CNS, bone, bone marrow and liver) and from treatment (cataract, radiation retinopathy, vascular occlusion after IAC, second cancers after radiotherapy). Heritable cases need lifelong surveillance for second tumours and pineoblastoma. With modern multimodal therapy, survival in high-income settings is excellent; the main determinant remains stage at presentation.^[6]

Permanent childhood hearing impairment is not uncommon: about 1 to 2 in 1,000 babies are born with a permanent deafness in one or both ears, rising to 1 in 100 among infants who spend more than 48 hours in neonatal intensive care. In England, about 1,400 babies are diagnosed each year. Most affected babies are born to families with no history of hearing loss, and most moderate-to-profound losses are not visible at birth.^[3]

The rationale is the sensitive period for language: early auditory stimulation shapes speech, language, cognitive and socioemotional development. Programmes therefore aim to identify permanent moderate, severe and profound deafness in newborns.^[2]

Screening is offered to all babies, ideally between 4 and 5 weeks of age and no later than 3 months. Results are usually given immediately.^[2][3]

• The first test is the automated otoacoustic emission (AOAE) test: a soft-tipped earpiece plays gentle clicks and the equipment detects the cochlea's response. It takes a few minutes and requires a settled or sleeping baby.^[2][3]
• If there is no clear response in one or both ears, a second AOAE is performed; if that is still not clear, an automated auditory brainstem response (AABR) test is used. AABR uses three skin electrodes and headphones, takes 5 to 15 minutes, and records the hearing nerve's electrical response.^[2][3]
• Babies with a clear response in both ears are discharged, with advice to monitor development; a minority with risk factors for late-onset loss are referred for targeted audiological follow-up. Babies with no clear response are referred for diagnostic audiological assessment within 4 weeks. Diagnostic tests are needed to confirm any loss; no intervention plan should start from screening alone.^[2][3]

Risk factors that bypass or extend the standard screen include microtia or atresia, confirmed congenital CMV infection, bacterial meningitis or meningococcal septicaemia, and programmable ventricular shunts, which require direct audiological assessment; syndromes associated with hearing loss, craniofacial anomalies including cleft palate, and confirmed congenital infection also need targeted follow-up.^[2]

Diagnostic audiology should ideally confirm the type and degree of loss by 3 months of age. The WHO 1-3-6 principle is widely used: screen by 1 month, diagnose by 3 months, and start early intervention by 6 months. The United States Early Hearing Detection and Intervention framework uses similar timings (screen by 1 month, confirmatory audiologic diagnosis by 2-3 months, entry to intervention by 3-6 months). Some programmes now work to a 1-2-3 standard. ^[7]

A normal screen does not mean normal hearing for life. Screening targets moderate-to-profound losses and is most sensitive at 2,000 to 4,000 Hz, so mild, low-frequency and isolated-frequency losses can be missed; childhood infections, head injury, noise and medicines can also cause later loss. Parental concern at any age is a reason for referral.^[7]

A child's hearing is classified in several useful ways: by timing (congenital or acquired, pre-lingual or post-lingual), by course (progressive or non-progressive), by cause (syndromic, non-syndromic, genetic or environmental) and, most importantly for management, by where the problem lies.^[7]

• Conductive hearing loss: sound does not reach the inner ear properly because of a problem in the outer or middle ear. Causes include otitis media with effusion (glue ear), impacted wax, foreign bodies, tympanic membrane perforation, cholesteatoma, otosclerosis and microtia or atresia. Many conductive losses are temporary and treatable; permanent conductive loss occurs with structural malformation or chronic disease.^[7]
• Sensorineural hearing loss (SNHL): the inner ear (cochlea) or the hearing nerve is affected. Congenital causes include genetic change (syndromic and non-syndromic, with consanguinity increasing risk) and congenital infection; cytomegalovirus deserves special mention because it is the most common infectious cause of congenital sensorineural hearing loss and may be silent at birth, with later progressive loss possible. Acquired causes include bacterial meningitis, ototoxic drugs (aminoglycosides, loop diuretics, cisplatin), hyperbilirubinaemia requiring exchange transfusion, prematurity and perinatal hypoxia, mumps and measles, head trauma and chronic loud noise.^[7]
• Mixed hearing loss contains elements of both and occurs when both parts of the ear are involved.

Conductive loss from glue ear is often observed first, because most middle-ear effusions resolve; ENT review is indicated for persistence, or when the sensorineural component is being masked. Hearing aids, bone-anchored devices and cochlear implants bypass or replace the damaged part, chosen by the age of the child, the type and degree of loss and the anatomy of the cochlea and auditory nerve.^[3]

Early intervention matters more than which device is chosen. The NHS/WHO model is a screen-diagnose-intervene cascade linked to developmental support for the child and family: signing, speech and language therapy and educational placement. Follow-up is lifelong, because conductive loss fluctuates and sensorineural loss can progress.^[2][3][7]

Children with hearing loss have a high prevalence of visual problems, and should have a vision assessment. Children with vision problems have a high prevalence of hearing problems, and should have a hearing assessment. Family history, siblings and consanguinity are important in both directions.^[7]

• Prematurity and neonatal jaundice: visual (ROP, cortical visual impairment) and auditory (SNHL after hyperbilirubinaemia, hypoxia, ototoxic therapy) risks run together; the red reflex and the hearing screen must both be done and tracked.
• Down syndrome and other genetic syndromes: high rates of hearing loss (often conductive plus sensorineural) and of refractive error and squint; annual hearing and vision checks are needed beyond newborn screening.
• Children with developmental delay or learning disability: use instrument-based vision screening and objective audiometry rather than relying on cooperation; hidden visual and hearing impairment is common and treatable.
• Pregnancy: any new "mitral stenosis" or vascular signs in the mother are irrelevant here, but antenatal infection (CMV, rubella) and ototoxic drug exposure are hearing risks for the baby; suspected congenital infection changes postnatal testing.

• The single transferable skill is red reflex testing with a direct ophthalmoscope in a dark room: it costs nothing and can pick up retinoblastoma and cataract before they cause irreversible blindness. Any white, asymmetric or absent reflex needs referral, even if an eye clinic is hours away.^[5]
• Where visual acuity charts are unavailable, fixation behaviour, the corneal light reflex, cover testing and the red reflex still identify most significant disease in young children. Effective screening does not require expensive equipment.^[4]
• For hearing, the WHO model emphasises early identification (including clinical suspicion and behavioural checks) plus basic ear care: treating acute and chronic suppurative otitis media, removing impacted wax, and referring persistent cases. These simple measures prevent much conductive loss.^[7]
• Hearing aids and implants are expensive and require follow-up; low-resource programmes also invest in sign language, inclusive education and family support, which improve outcomes even when devices are unavailable.
• Retinoblastoma outcomes in low-resource settings are driven by late presentation and limited access to examination under anaesthesia and chemotherapy; awareness of leukocoria among parents, teachers and primary workers, and rapid referral pathways, matter more than any single technology.^[6]

• The red reflex test is performed from birth in a darkened room with a direct ophthalmoscope; an asymmetric, dull or absent reflex, or leukocoria, is abnormal until proven otherwise.
• Constant strabismus persisting beyond 4 months of age does not resolve and needs referral; acute onset, neurological features or an abnormal red reflex make it urgent.
• UK vision screening is offered at 4 to 5 years using a crowded logMAR chart; US screening includes a red reflex at birth, inspection through infancy, and acuity or instrument-based screening by the preschool years.
• Amblyopia is a developmental disorder of the cortex; its treatment is optical correction, then patching (typically 2 hours daily) or weekend atropine for moderate disease, with best results before about 7 years.
• Most children (about three-quarters) with moderate strabismic or anisometropic amblyopia reach VA 20/30 or better six months after starting treatment.
• Retinoblastoma presents most often as leukocoria; incidence is 1 in 15,000 to 20,000 live births, two-thirds are diagnosed by age 2 years, and 95% by age 5.
• Retinoblastoma is driven by RB1 inactivation; heritable cases make up 30% to 40%, are 80% bilateral and present earlier.
• Diagnosis is clinical and must never be by biopsy; enucleation, VEC chemotherapy (vincristine, etoposide, carboplatin) and intra-arterial melphalan are the main treatments; EBRT is now reserved for metastatic or residual disease.
• Newborn hearing screening uses AOAE followed by AABR if needed, ideally by 4-5 weeks and no later than 3 months, aiming at permanent moderate, severe and profound deafness. ^[7]
• The programme targets a loss of 40 dB nHL or worse averaged across frequencies; about 1 to 2 in 1,000 newborns are affected (1 in 100 after 48 hours of neonatal intensive care). These programme phrases are quoted from UK guidance.
• Diagnosis and intervention should follow the 1-3-6 principle (screen by 1 month, diagnose by 3 months, intervene by 6 months). ^[7]
• Conductive loss (outer or middle ear) is common and often treatable; sensorineural loss (cochlea or nerve) is usually permanent; mixed loss has both components.
• Congenital cytomegalovirus is the most common infectious cause of sensorineural hearing loss and may be asymptomatic at birth.
• Hearing and vision problems overlap in children: screen for the other sense whenever one is affected.

• Paediatric immunisation and prevention
• Child abuse and neglect (recognition, examination and referral)
• Neonatal sepsis (early recognition and antibiotics)
• Congenital adrenal hyperplasia (newborn screening context)
• Febrile seizures (papilloedema and the red reflex)
• Meningitis (hearing loss as a complication)
• Retinopathy of prematurity (mentioned above, not covered)
• Cochlear implant and hearing rehabilitation services
• Speech and language development
• Educational impairment and learning disability

Clinical thresholds in this topic come from UK screening documents, US professional statements and a 2024 review of retinoblastoma management; where programmes differ (for example screening age 4-5 years in the UK versus 3-5 years in the US), each is named. Follow your own national programme: ages, charts and referral cut-offs are set locally and change over time.