Introduction
The contact lens practitioner is a key member of a multidisciplinary team involving paediatric ophthalmologists, optometrists and orthoptists concerned with ocular health and visual development of the child. Fitting infants and children with contact lenses is a challenging yet rewarding area of clinical contact lens practice. Contact lenses play an important role in the correction of complex refractive errors in infants and young children ( ). They can also be used in the management of binocular vision anomalies, for therapeutic and prosthetic purposes, and for elective wear in older children and teenagers.
Indications
Aphakia
One of the most common indicators for contact lens fitting in infants is aphakia resulting from the surgical removal of the crystalline lens because of a congenital cataract. The global prevalence of congenital cataract ( Fig. 27.1 ) is reported as being between 2.2 per 10,000 and 13.6 per 10,000, varying between countries due to the presence of newborn screening, rubella immunisations, and population genetics ( ). Of these cases, around 45% have unilateral cataracts. Aphakia can also result from lens subluxation, as seen in Marfan’s syndrome, or ectopia lentis. Trauma to the eye may result in the immediate loss of the crystalline lens or subsequent development of a traumatic cataract, which may require surgical intervention.
Refractive management of bilateral aphakia can be achieved with spectacles ( Fig. 27.2 ). However, the drawbacks of aphakic spectacles include the weight of the lenses and difficulty in achieving a good frame fit in babies and young infants. In addition, the maximum power of lenses is restricted, even in lenticulated form, to around +26.00 D.
Fig. 27.3 shows a 3-week-old aphake wearing a silicone hydrogel contact lens of around +35.00 D power.
In cases of unilateral cataract, contact lens correction is essential for managing the resultant anisometropia.
Surgery for congenital cataract is usually performed between 6 and 8 weeks of life for unilateral cataract, or between 6 and 10 weeks of life for bilateral cataracts ( ) to limit deprivation amblyopia, so it is vital to be aware of the rapid changes in the ocular dimensions that occur within the first few months of life. The average radius of curvature in a newborn is around 6.90 mm and this will flatten rapidly in the first 6 months of life ( ). Axial length will increase rapidly from around 17.00 mm in neonates to 21.00 mm within the first 6 months of life and then more slowly during later infancy and childhood ( ). These changes cause a ‘myopic shift’, with the aphakic correction decreasing from +35.00 to +20.00 D in the first few years of life. However, eyes with congenital cataract can have associated disorders such as persistent hypoplastic primary vitreous and microphthalmos, which require steeper-radii lenses and powers in excess of +50.00 D.
Average fittings of a high-water-content hydrogel lens and silicone hydrogel lens based upon age, corneal radius and diameter are shown in Table 27.1 .
| Age (months) | BOZR (mm) | TD (mm) | Power (D) |
|---|---|---|---|
| 1 | 7.00 | 12.00 | +35.00 |
| 2 | 7.20 | 12.50 | +32.00 |
| 3 | 7.50 | 13.00 | +30.00 |
| 6 | 7.80 | 13.50 | +25.00 |
| 12 | 8.10 | 13.50 | +20.00 |
a These lenses would form the basis of a paediatric aphakic diagnostic fitting set.
As infants in the early stages of visual development require a focal length of around 30–50 cm in order to see a face, the power of the selected contact lens is usually 2–3 D greater than the ocular refraction. This overcorrection should be reduced from 18 months to 2 years when the toddler becomes more mobile and aware of distant objects. A reading correction or bifocals can be prescribed from around 3–4 years of age when the child starts preschool education.
Pseudophakia
Recommendations regarding insertion of a primary intraocular lens (IOL) at the time of cataract extraction or leaving the eye aphakic with secondary IOL surgery later have changed over time as evidence has emerged. As microsurgical techniques improved, IOL technology advanced and the growth and development of the eye became better understood, it become more popular to insert an IOL at the time of cataract surgery ( ). Fitting an IOL at the time of cataract surgery has the advantage of constant partial refractive correction thereby eliminating noncompliance with therapy as a contributing factor to amblyopia development. IOLs more closely resemble the optics of the natural crystalline lens and they reduce the amount of anisometropia in unilateral cataract ( ). To obtain a satisfactory long-term refractive result, allowances must be made for the growth of the eye, so pseudophakic eyes are deliberately left hypermetropic to allow for axial elongation with the corresponding myopic shift. The final refractive status, following cessation of axial elongation, is aimed at emmetropia or low myopia ( ).
The risks associated with primary IOL insertion include capsular opacification, secondary glaucoma, uveitis, pupil displacement and IOL decentration, meaning that further surgical intervention may be required. The Infant Aphakia Treatment Study (IATS) ( ) allocated infants to either primary IOL insertion or aphakic contact lens correction groups and they found that at least one adverse event occurred in 81% of the IOL group, compared to 56% of the contact lens group with adverse events including corneal ulcers, corneal abrasions and punctate keratopathy ( ). The IATS study group also concluded that there was no difference in visual outcomes at 5 years for those infants with an IOL compared to contact lens correction, with the median visual acuity being +0.90LogMAR. The UK and Ireland ‘IOLUnder2’ cohort study also found that there was no benefit of primary IOL, compared to contact lens correction, to visual outcomes for infants under 2 years in both unilateral and bilateral cataract ( ).
It is therefore recommended that for infants under 2 years of age they are initially left aphakic and corrected with contact lenses or spectacles with plans for future secondary IOL to be considered when older ( ). In certain circumstances, however, IOLs should be considered as an option where there are concerns regarding contact lens handling resulting in significant periods of uncorrected aphakia ( ).
High Myopia
High myopia in infants and young children is not uncommon and correction with spectacles is the accepted practice. However, in high myopia, spectacles have the disadvantage of reducing the retinal image size, inducing peripheral distortion and reducing the effective visual field (especially with lenticulated lenses). Contact lens correction is warranted where spectacle correction is problematic or normal visual development is threatened. High myopia (>10 D) may be present from birth and is related to a number of ocular and systemic disorders ( ). High myopia is also associated with craniofacial anomalies, which can make the wearing of spectacles difficult ( Fig. 27.4 ).
The myopic eye is larger than normal and tends to have flatter than the average corneal radius and larger corneal diameter. Adult-sized lenses can often be used in young infants and children. Myopia can also result from buphthalmos where the corneal diameter is much larger than normal (>12.5 mm) and so requires a flatter and larger lens.
Contact lenses in unilateral high myopia have been shown to be more satisfactory than spectacle lenses in the management of amblyopia in regard to cosmesis, comfort and treatment compliance ( ).
Ocular Motility Disorders
Contact lenses can be useful in the management of ocular motility disorders ( ). Some uses include:
- •
aniseikonia induced by anisometropia exceeding 6 D;
- •
accommodative esotropia (older children);
- •
nystagmus; and
- •
occlusion.
Irregular Astigmatism
Irregular astigmatism derived from primary corneal ectasia is extremely rare in childhood. Most causes of corneal irregularity are secondary in nature – for example, following corneal infection or laceration ( Fig. 27.5 ). Neutralization of irregular astigmatism is important during the visual development period so as to prevent deprivational amblyopia. The optimum form of contact lens correction in this situation is a rigid gas-permeable lens, although sometimes if the irregularity is less severe, a toric soft lens may suffice. Rigid gas-permeable lenses have been shown to offer a useful refractive treatment alternative in children with traumatized eyes ( ).
Tinted and Prosthetic Lenses
The aim of this type of contact lens in paediatric use is to enhance visual performance by reducing the effect of photophobia or improving the cosmesis of the child by camouflaging an ocular defect. The most common reasons for fitting these lenses in childhood are:
- •
albinism;
- •
aniridia;
- •
achromatopsia;
- •
iris defects, e.g. coloboma;
- •
nanophthalmos or microphthalmos; and
- •
corneal anomalies, e.g. sclerocornea or Peter’s anomaly.
The fitting of these lenses is described in more detail in Chapter 21 .
Therapeutic Lenses
Silicone hydrogel lenses have been shown to be safe and efficacious for continuous-wear therapeutic use in children ( ). Therapeutic contact lens use in the paediatric population is similar to its use in adults – mainly for the relief of pain, promotion of corneal healing and protection of the cornea. An example of their use is reported by , where two cases of upper-eyelid entropion secondary to neonatal conjunctivitis resolved spontaneously following the insertion of bandage contact lenses. Previously early surgical intervention was advocated to correct the eyelid abnormality and prevent any permanent corneal scarring and visual loss. The fitting of therapeutic lenses is described in more detail in Chapter 28 .
Elective Contact Lens Wear in Children
Contact lenses can be considered as an additional option for full-time spectacle wear or for use while participating in sporting activities for both myopic and hypermetropic children and teenagers. A study by found that both rigid gas-permeable and soft contact lenses could be considered, although gas-permeable lenses took longer to adapt to and resulted in slightly less comfortable wearing times. Daily disposable contact lenses are particularly useful whilst participating in sporting activities, especially if wear is intermittent. The increased availability and range of parameters available as daily disposable contact lenses, as well as negating the need for a daily cleaning and storing regime make them particularly attractive to children.
published the results of an international survey to determine the types of contact lenses prescribed for infants (aged 0–5 years), children (6–12 years) and teenagers (13–17 years). This survey has continued beyond 2011, and Efron and Morgan (unpublished data) have updated this data. Up to 1000 survey forms were sent to contact lens fitters in each of 49 countries between January and March every year for 21 consecutive years (2000–2021, inclusive). Practitioners were asked to record data relating to the first 10 contact lens fits or refits performed after receiving the survey form.
Data were received relating to 240,340 fits [295 infants, 5615 children, 27,976 teenagers and 206,454 adults (age ≥18 years)]; the proportion of minors (<18 years old) fitted varied considerably between nations, ranging from 23% in Moldova to 0.5% in Iran ( Fig. 27.6 ). Compared with other age groups, infants tend to be prescribed a higher proportion of rigid, soft toric and extended-wear lenses, predominantly as refits for full-time wear, and fewer daily disposable lenses. Children are fitted with the highest proportion of daily disposable lenses and have the highest rate of fits for part-time wear. Teenagers have a similar lens-fitting profile to that of adults, the main distinguishing characteristic being a higher proportion of new fits. Orthokeratology fits represented 28% of all contact lenses prescribed to minors. concluded that patterns of contact lens prescribing to infants and children are distinctly different to those of teenagers and adults in a number of respects.
