Paediatric cataract surgery
There are many factors to consider when dealing with younger patients.
Difficult patients, difficult eyes, difficult evaluation… difficult decision-making, difficult follow-up and often difficult parents! With so much difficulty, why should we invest time and effort to know paediatric ophthalmology better and what should we know? I had discussed why, in a previous article, and here will discuss briefly on some of what we need to know.
Growth of the eye: Axial length of about 14.5-15.5mm and K value of about 52 dioptres at birth changes during three growth phases: rapidly from birth to two years followed by two slow phases between two-to-five years and five-to-10 years.
Hypermetropia at birth increases until about seven years, then slowly decreases till the eyes reach adult dimensions by about 16 years of age. Children with myopia before 10 years generally progress to more than -6D and should be referred to a paediatric ophthalmologist for possible treatment with low-dose atropine eyedrops. The importance of spending time outdoors and avoiding handheld digital devices should be stressed. Accurate refraction and amblyopia treatment is very important. Sometimes, decreased vision may be untreatable and the ophthalmologist should guide parents about resources available for such patients.
Examination of children: Techniques providing maximum information while minimising trauma to the child and frustration for the examiner are ideal. Sometimes, however, it may be necessary to use restraint for examination or to examine under anaesthesia.
Visual acuity is assessed by Snellen chart in cooperative children or grossly with toys kept at different distances. For pre-verbal/ uncooperative children, pattern visually evoked potential, preferential looking test, fixation behaviour, Allen cards etc. help. A lit-up small toy acts as an accommodative near target while simultaneously helping to assess corneal light reflex. In young infants, the red reflex (Brückner test) can help diagnose refractive errors, misaligned eyes, visually significant media opacities and even retinoblastoma. Glare testing assesses the real impact of minimal central opacities on vision. Parents/siblings should be evaluated if genetic abnormalities or conditions such as keratoconus are suspected.
The paediatric eye is small, has low ocular rigidity and elastic structures. Surgery and postoperative management are both challenging and unpredictable. Cataract is the leading cause of treatable paediatric blindness. Early referral and if required, systemic/ genetic evaluation and Serum TORCH titres are performed.
Timing of surgery and timing, material and power of IOL need to be decided. Vision is subcortically mediated for the first six weeks of life and there is some resistance to developing amblyopia within this age. Therefore, surgery for unilateral congenital cataracts by four-to-six weeks and bilateral congenital cataracts by six-to-eight weeks followed by refractive correction and occlusion therapy can avoid stimulus-deprivation amblyopia and result in good vision with fusion and stereopsis.
The case for multifocals in paediatric eyes is weak, considering the expected refractive shift and possible deleterious effect of decreased contrast sensitivity, glare and haloes on the developing visual system.
Corneal opacities should be evaluated carefully to assess the need for surgery. For eyes requiring corneal transplantation, close postoperative follow-up is a must. In very young children, difficult suture management, inability of children to express symptoms, secondary glaucoma and need for examination under anaesthesia can all lead to an increased risk of rejection and other complications, possibly more deleterious than the primary disease.
Older and alert children who are cooperative for examination together with aware and responsible parents can increase success rates of keratoplasty in children. Decisions should therefore be made judiciously and after a thorough examination and discussion with parents.
Glaucomas, as in all age groups, have to be handled aggressively to prevent permanent irreversible visual loss. Brimonidine in children can cross blood-brain-barrier and should ideally be avoided. Mitomycin-C is often required to deal with the aggressive scarring response seen commonly in children.
Issues such as cataract, glaucoma, corneal pathology etc. may need to be tackled simultaneously or sequentially in anterior segment developmental anomalies, often requiring multiple complex surgeries.
Premature babies must undergo screening for Retinopathy of Prematurity and be given laser/ anti-VEGF/ surgical treatment according to indication and should have continued monitoring. Retinal examinations and other evaluations of the pre- and post-geniculate system are indicated, especially in case of delayed visual maturation in children.
Students complaining of headaches when studying should have a complete examination, including refraction and convergence assessment, both of which can be treated easily by spectacles and pencil push-up exercises respectively. The latter may also help keep certain exophorias under control.
Nystagmus can be secondary to motor or sensory defects or neurological abnormality. History of inherited ocular/ systemic conditions in the family, maternal infections during pregnancy, difficult labour and prematurity should be taken. Treatment of cause as well as prism spectacles and surgery for nystagmus are possible. Oculoplastic conditions such as ptosis need surgery not only if the visual axis is occluded but also to improve confidence levels and the psycho-social development of the child.
Nasolacrimal duct obstruction (NLDO) in infants presents with epiphora and/or crusting. Infantile glaucoma is a differential for this and hints favouring it over NLDO include photophobia, enlarged cornea, Haab’s striae etc. Since 90% of congenital NLDO spontaneously resolves by nine-to-12 months of age, conservative management in the form of lacrimal massage and topical antibiotics when required is preferred. Probing may be done if not resolving beyond nine-to-12 months.
Other situations that we may come across sometimes include congenital and acquired ocular infections, paediatric uveitis, ocular and orbital tumours, phacomatoses, various vitreoretinal, optic disc, and metabolic diseases etc. When required, these should be referred for treatment. The presence of dysmorphic features and systemic abnormalities should alert to need for systemic evaluation.
Finally, the shaken baby syndrome secondary to physical abuse, generally by the caregiver, should be suspected by inconsistent or poor correlation of history with type/ degree of injury as well as by observing the family social interaction. Violent shaking causes unilateral/ bilateral retinal haemorrhages in 85% of cases. Vitreous haemorrhage, perimacular folds and retinoschisis may also be seen.
Anterior segment and adnexa may be quiet but other prominent evidence such as subdural haematomas, subarachnoid haemorrhage, intracranial oedema, ischaemia, contusion and cerebral atrophy may be seen. Bruises, metaphyseal fractures, broken ribs etc. and signs of blunt trauma such as periorbital oedema, echhymoses, subconjunctival haemorrhage, hyphema, lens dislocation etc. may also be seen in child abuse. In many countries, child abuse is required by law to be reported to the appropriate governmental agencies.
Dr Soosan Jacob is Director and Chief of Dr Agarwal’s Refractive and Cornea Foundation at Dr Agarwal’s Eye Hospital, Chennai, India and can be reached at email@example.com.