Children can be fit into contact lenses for more reasons than just to be glasses-free. There are various indications for contact lens use in infants and children, and whether or not you are in a pediatric specialty practice, you may encounter patients with these conditions and types of contact lenses.
Aphakia in pediatric patients
Congenital cataracts occur in about 3 to 4 per 10,000 births.1 Despite its seemingly low prevalence, its consequences on vision are enormous, causing dense visual deprivation if untreated. Cataracts can also be secondary to trauma and systemic medications. If an intraocular lens is not implanted, management after cataract extraction is often with contact lenses. Silicone elastomer lenses and rigid gas permeable (RGP) lenses have been established as relatively safe, well-tolerated options.2
Historically, the silicone elastomer lens Silsoft Super Plus (Bausch & Lomb, Rochester, NY, USA) was the lens of choice given its ease of fit, extended wear modality, and high oxygen permeability. However, as of summer 2021, Silsoft production has been temporarily discontinued. Fortunately, there are suitable alternatives for fitting infants and children with aphakia.
The Flexlens Pediatric Aphakic lens (X-Cel Contacts, Duluth, GA, USA) is a silicone hydrogel lens for aphakia. This lens is highly customizable, which is ideal for very steep corneas and microcorneas. The power range is impressive, with the ability to order with the precision of a quarter-diopter. The Flexlens, however, has a lower oxygen permeability and should be cleaned and removed nightly.
With the indefinite discontinuation of Silsoft, the Flexlens Pediatric Aphakic lens stands to be an acceptable lens choice.
Comparison of parameters and characteristics of Silsoft vs. Flexlens
| Silsoft | Flexlens | |
|---|---|---|
| Base curves | 7.5 to 7.9 mm, 0.2 mm steps (Super Plus) | 6.0 to 11.0 mm, 0.1 mm steps |
| 7.5 to 8.3 mm, 0.2 mm steps (Aphakic) | ||
| Diameter | 11.30 mm (Super Plus) | 10.0 to 16.0 mm, 0.1 mm steps |
| 11.30 mm, 12.5 mm (Aphakic) | ||
| Power | +23.00D to +32.00D, 3.00D steps (Super Plus) | 0 to +50.00D, 0.25D steps |
| +12.00D to +20.00D, 1.00D steps (Aphakic) | ||
| Dk | 340 | 60 |
| Modality | Daily wear, extended wear | Daily wear |
Table 1
Considerations with RGP lenses
RGP lenses are another excellent option, because they can be easily customized for optimal fit and vision. When compared to silicone elastomer lenses, RGP lenses are known to be optically superior but have generally equivalent visual outcomes in the setting of aphakia.2 These lenses are generally daily wear, but certain materials have been shown to be safe when worn as 1-week extended-wear.3
When keratometry data is not available, choosing a base curve based on age norms is appropriate. A 20-diopter condensing lens should be used to zoom in on the fit. View with a white light transilluminator for a soft lens or a cobalt blue light, like a Burton lamp or Bluminator(Eidolon Optical, LLC, Natick, MA, USA), for a RGP lens after fluorescein instillation. An optimal soft lens fit will be centered and have some movement with blinks. An optimal RGP lens fit will have some central clearance with some peripheral edge lift.
Corneal curvature measurements by age and extrapolated base curve radius
| Age in months | Expected Range of K’s4 | Base Curve Radius |
|---|---|---|
| 0-3 | 46-49 D | 6.9-7.3 mm |
| 3-6 | 44-47 D | 7.2-7.6 mm |
| 6-12 | 44-46 D | 7.3-7.7 mm |
Table 2
* rounded to nearest diopter
** rounded to nearest tenth
* rounded to nearest diopter
** rounded to nearest tenth
For both types of lenses, a proper refraction is critical to optimize vision. Cycloplegia is not necessary given there is no natural crystalline lens that accommodates, however mydriatic drops can still be useful to improve view of the retinoscopic reflex. It is important to build in a 2 to 3 diopter-add into the lens power for infants to accommodate their short viewing distances. This should eventually be incorporated into a bifocal spectacle lens after the child is ambulatory.
Corneal irregularities in children
Penetrating eye injuries are disproportionately common in children, with the majority involving the cornea. Penetrating trauma by mechanical pencil, central corneal scar via laundry detergent pod explosion, partial thickness corneal laceration by metal rake–I’ve seen it all!
Other causes of corneal irregularities in pediatric-aged patients are eye infections and keratoconus. All of these problems can warp the cornea and leave children with challenging visual sequelae. The resultant irregular corneal curvatures are generally not well corrected by soft lenses or spectacles, so other lens options should be considered.
Figure 1 illustrates the different contact lens options in the case of a corneal scar.
Figure 1
Spherical corneal RGP can be explored as the first trial lens, however special designs may be needed if the lens is not well-centered. Back surface toric, bitoric, and reverse geometry designs can be utilized to optimize fit and comfort.
Hybrid lenses have a rigid central zone and a soft skirt, combining the visual quality of an RGP lens with the comfort of a soft lens. Despite this advantage, its use is limited to mild to moderate irregularities that are underneath the landing zone.
Scleral lenses are large diameter RGP lenses that land on the sclera while vaulting over the cornea with a fluid reservoir. Perceived difficulty with scleral lens handling should not be a reason to withhold recommending these lenses, as there has been demonstrated successful use in pediatric patients.5
Contact lenses and myopia control
There is still some discussion circling around myopia as a simple refractive error versus a disease. However, it is well-established that there is a role of contact lenses in myopia management to slow down its progression. Though contact lenses for myopia management have not been deemed medically necessary by insurance plans yet, there are clear benefits to curbing the risk of retinal changes associated with myopic axial elongation.
MiSight 1 day contact lenses (CooperVision, Inc, Scottsville, NY, USA) entered the field in November 2019 as the only FDA-approved option to slow myopia progression in children. It is important to distinguish that a child’s myopia is not only being addressed refractively but is being treated by the lens’ dual-focus optics. The concentric alternating powers in the lens create myopic defocus that has effectively slowed axial elongation in children with myopia.6
This success has been demonstrated up to age 14 in 6-year data (publication pending), though cumulative effects are compounded when introduced at an earlier age. Seven-year data (publication pending) showed that these benefits are solidified even after the treatment is discontinued. In addition to its impressive results, MiSight has a great safety profile and high acceptance rate,6 making it a promising treatment for children with myopia.
Figure 2 shows the dual-focus optic design of MiSight lenses.6
Figure 2
From a prescriber standpoint, the fitting could not be more straightforward. A well-centered lens with good coverage and movement with blinks are common characteristics of any well-fitting soft lens. The power should be finalized with the least amount of minus to achieve good distance visual acuity. The MiSight lens earns praise all-around by the child, the relieved parent, and the prudent prescriber as a great lens.
The role of orthokeratology
Orthokeratology (ortho-k) is another excellent option with a long successful track record of slowing myopia,7 albeit off-label use. These reverse geometry RGP lenses reshape the central part of the cornea overnight. The goal is to produce a classic bulls-eye pattern, though interestingly some decentration has been shown to have extra protection against myopia.8,9 The treatment zone size, typically 4 mm, can be reduced for a greater protective effect.8
Recently, toric ortho-k for children with corneal astigmatism has also shown early success.10 For the right candidate, orthokeratology can offer the substantial advantages of clear lens-free daytime vision along with slower myopia progression.
Figure 3 demonstrates a classic bulls-eye fluorescein pattern for orthokeratology (central bearing, mid peripheral pooling, peripheral edge lift).
Figure 3
Wrap-up
Even outside of the conditions discussed, there is a clear role for contact lenses in children distinct from the armamentarium of common daily wear lenses. Being confident with the available lens types can translate to success for your next routine or challenging pediatric lens fit.
References
- Holmes JM, Leske DA, Burke JP et al. Birth prevalence of visually significant infantile cataract in a defined U.S. population. Ophthalmic Epidemiol 2003 Apr:10:67-74.
- Russell B, DuBois L, Lynn M et al. The Infant Aphakia Treatment Study Contact Lens Experience to Age 5 years. Eye Contact Lens. 2017 Nov; 43(6):352-357.
- Salterelli D. Hyper oxygen-permeable rigid contact lenses as an alternative for the treatment of pediatric aphakia. Eye Contact Lens. 2008 Mar;34(2):84-93.
- Capozzi P, Morini C, Piga S et al. Corneal Curvature and Axial Length Values in Children with Congenital/Infantile Cataract in the First 42 Months of Life. Invest Ophthalmol Vis Sci. 2008 Nov;49(11):4774-8.
- Rathi VM, Mandathara PS, Vaddavalli PK et al. Fluid filled scleral contact lens in pediatric patients: Challenges and outcome. Cont Lens Anterior Eye. 2012 Aug;35(4):189-92.
- Chamberlain P, Peixoto-de-Matos SC, Logan NS et al. A 3-year Randomized Clinical Trial of MiSight Lenses for Myopia Control. Optom Vis Sci. 2019 Aug;96(8):556-567.
- Lee YC, Wang JH, Chiu CJ. Effect of Orthokeratology on myopia progression: twelve-year results of a retrospective cohort study. BMC Ophthalmol. 2017 Dec 8;17(1):243.
- Lin W, Li N, Gu T et al. The treatment zone size and its decentration influence axial elongation in children with orthokeratology treatment. BMC Ophthalmol. 2021 Oct 12;21(1):362.
- Wang A, Yang C. Influence of Overnight Orthokeratology Lens Treatment Zone Decentration on Myopia Progression. J Ophthalmol. 2019 Nov 15;2019:2596953.
- Jiang J, Lian L, Wang F et al. Comparison of Toric and Spherical Orthokeratology Lenses in Patients with Astigmatism. J Ophtahlmol. 2019 Feb 20;2019:4275269.
