Scleral lenses have many therapeutic benefits for young children. Compared to soft lens designs, the rigid GP material of scleral lenses is easier to handle, they have great initial comfort, are stable, and have excellent optics. Scleral lenses manufactured in high-Dk materials that vault the corneal surface enjoy a low complication rate (Sweeney et al, 2006). Scleral lenses are indicated in pediatric cases when it is difficult to achieve an acceptable fit or sufficient vision with other lenses. These large, fluid-filled lenses can also be used to promote healing in pediatric patients who have severe dry eye or ocular surface disease such as neurotrophic keratitis or graft-versus-host disease.
Although there are many benefits to fitting scleral lenses in children, they are sparingly prescribed in kids. One reason for this is the perceived difficulty of fitting these lenses in children. The following offers an easily implementable approach for fitting scleral lenses in pediatric patients.
Start with the Diameter
The first consideration when choosing an appropriate scleral lens diameter is patients’ horizontal visible iris diameter (HVID). Mini-scleral lenses have a diameter that is up to 6mm larger than the HVID, whereas large scleral lenses have a diameter more than 6mm larger than the HVID (Johns and Barnett, 2017). For example, a 16mm lens on a patient who has a 9mm microcornea would be considered a large scleral lens, but in a patient who has a 12mm cornea, it would be considered a mini-scleral lens.
The condition being managed also informs the choice of lens diameter. For example, to provide as much protection as possible for children who have ocular surface disease and severe dry eye, large scleral lens diameters are indicated. Mini-sclerals may be more appropriate for young children who have normal corneas with high refractive errors or for those who have irregular corneas such as keratoconus.
Choosing Sagittal Depth
Scleral lenses are designed to completely vault the cornea. Special testing is often difficult to perform on children, making diagnostic fitting crucial for determining the appropriate lens sagittal depth.
The initial sagittal depth of the lens can be based on patients’ ocular sagittal depth. Estimate this by looking at the side profile of the eye globe and determining whether the ocular sagittal depth is typical, steep, or flat. Learning to gauge sagittal depth using fluorescein and a cobalt blue light is especially useful to ensure adequate scleral lens corneal clearance in kids (Figure 1).
Calculating the Power
For young and/or non-verbal children, determine the lens power by performing retinoscopy over the surface of the lens. In older children and adolescents, a subjective refraction can be performed over the diagnostic lens to determine the final lens power.
A need exists to fit some children with scleral lenses. While there are special challenges in fitting scleral lenses on pediatric patients, these challenges can be overcome, and the results make the effort worthwhile. Gauging lens fit and final refractive power are learnable skills, and the very nature of the design allows some wiggle room. Learning to fit scleral lenses for children prioritizes ocular health and will set your practice apart. CLS
For references, please visit www.clspectrum.com/references and click on document #297.