Responses to this exercise were a little different compared with our other interactives. There were fewer responses, but those we did get were very comprehensive and detailed. Indeed, some had detail enough to be considered as mini-features. Does this imply that the topic is of interest to a few, but to those few it is a real passion?
The Discussion
Your were asked to consider the following scenario.
A parent attends your practice with their boisterous three-year old son. He has been prescribed a correction for full time wear, but his mother is very concerned that he is not going to be keen on wearing spectacles.
His Rx includes the following information;
R: +4.25/-1.00 x 180
L: +4.75
PD R 25 L 24
The mother wants something as close to an adult fashion frame as possible. She also wants something that will withstand the likely violent onslaught the boy will unleash upon the specs.
• In what ways should a frame for a very young child differ from an adult frame (please include specific parameters in your discussion)?
• What features would you want the frame to include to ensure as long a life as possible?
• Assuming money is not a consideration, what would you recommend for lens material and design?
Adult versus Child
The first point of interest concerned your views on why adult and paediatric frames are necessarily different. Much of the finer details, such as specific measurements, were covered in the source material and readers showed their full understanding of these.
A good general starting point raised was as follows: ‘It is important to remember that a child’s face is not a scaled down version of an adult’s face, but also important not to assume that a parent/guardian is aware of this.
They may want the fashions of an adult styled frame, but have to be made aware that the fitting is very different.’ Having as wide a range of frames that fit the young face and is appealing enough to ensure good compliance with wear is essential – and not always as easy to ensure as might be expected. A good understanding of specific parameter differences was demonstrated across the board. Responses included the following:
‘Frames for very young children should have a small eye size. The bridge should be comparatively large and the frontal and splay angles should closely match that of the child. Bridges with a negative bridge projection should be considered if the child has an underdeveloped nasal bridge. Also, a saddle bridge could be used to spread the weight on a child’s face better than an adult-type bridge, and this is also good at absorbing any impact.’
‘As children often have a wide temple/head width comparative to their PD, the temple width of a child’s frame is usually large compared to the eye size of the frame. The pantoscopic angle should be about zero degrees or even slightly increased to reduce the chance of lashes rubbing on back of lenses.’
A more succinct but appropriate response was, ‘Reduced crest height, larger frontal angle, widened splay angle, smaller bridge projection, smaller head and temple width and less pantoscopic tilt.’
And, lastly, ‘The frame should have a boxed centre distance similar to PD giving best form of lens.’
Frame Features
Thoughts regarding frame design focused upon the plastic versus metal decision, the need to consider potential allergic response and, importantly in this particular case, the importance of providing something that will survive the rigours of childhood activity.
‘The frame should be lightweight, flexible, hypoallergenic and robust – made of one piece of plastic with no metal parts to reduce risk of facial trauma. The sides on frames for very young children could be curled or loop-ends as opposed to hockey ends.’ Others suggested the frame should be a ‘one-piece plastic frame with no metal hinges which might break easier than a one-piece plastic frame’ and include ‘a saddle bridge which copes with impact best.’
A preference for plastic was argued thus; ‘Although metal frames can help solve many fitting problems, the extra components and hardness of the material can create a safety issue and so a good quality plastic frame preferably with sprung loaded side might be the better option.’
Another said they would recommend ‘a frame with no metal part while very young. Sides must fit well to avoid slipping but not so tight as to damage cartilage behind ears. Silicone tips would be ideal.’
A contrary view to this was, ‘As the boy is boisterous, I would be looking at a frame with curl sides (to keep on securely during play), spring loaded sides and, if possible, titanium for maximum strength. I would probably, through personal preference, recommend a saddle bridge.’
In summing up, a succinct answer was as follows: ‘The features I would look for in a frame for a child of this age and prescription are:
• a large enough bridge and a frontal and splay angle that matches that of the child
• negative bridge projection to ensure the frame sits far enough away from eyelashes, to prevent them rubbing on the back of the lens
• boxed centre distances similar to that of the child’s PD (to reduce amount of decentration required when glazing, to reduce thickness, make the spectacles lighter and more comfortable and offer the best cosmesis
• consider curled sides, as the child is described as boisterous (so I assume is quite active!) to ensure the frame stays in position. They are also softer, so often more comfortable to wear
• if the parent isn’t keen on the curled side (as cosmetically they do not look like a shrunken adult frame, which is what she has requested), then a well-fitting drop end side, with length to bend and drop correctly measured is best
• a saddle bridge is good at absorbing any impact of a boisterous child’s activities, but again may not be the ‘look’ the parent is after. If so, a pad on arms frame can be chosen with soft, silicone nose pads adding as much grip as possible is worth considering.
Only a few, such as this response, mentioned specific frames. ‘We currently stock Nanovista frames that have soft rubber bridge pieces the sides are interchangeable to convert to use with a headband to further secure them. We’ve also used Tomato and Jelly Bean frames that work well to ensure a good bridge fitting and that the specs are secure.’
Children's frames
Lens Features
Most answers focused on the material to be recommended and though overall Trivex came out as most popular choice, there were some varied views.
‘Assuming money is not a consideration, I would recommend Trivex for low to medium prescriptions, and for high hypermetropic powers high index lenses of small blanks.’
‘High index plastic lenses will be dispensed if money is not an issue, otherwise CR39 with a mini blank size can also be considered, to reduce thickness. Trivex is also a consideration, with its superior V value and durability compared to polycarbonate lenses.’
Another said they would ‘recommend a plastic lens, polycarbonate if possible, for better impact resistance and for a thinner and lighter lens. Better still, Trivex for good impact resistance, better image quality, less chromatic aberration and improved UV protection than polycarbonate. Also, consider a small blank size to reduce weight and thickness.’
The ideal lens material (if money is no object for the parent) would be a Trivex or polycarbonate lens. They have high impact resistance properties, so good for active lifestyles. It is also a thinner/lighter material to help with the cosmetics of the lenses. You could consider upgrading to even higher index materials (such as 1.74), but this is going to be even more costly to the parent, and is likely the prescription may need frequently changed. A MAR coated lens would also be ideal, especially as children are using tablet computers from such a young age. (My 3-year-old uses our tablet computer more than me!). I would also discuss with the parent whether Transitions lenses would be of use, especially as full-time wear is required, so would save having to purchase/swap to a separate pair of sunglasses. Where lens form was mentioned, the preference seemed to be for asphericity.
‘A high index aspheric form will give the best cosmetic appearance if money was not a consideration.’ Another, ‘I would want to have strong and robust lenses, perhaps polycarbonate (but this has a low V value of 30), Trivex better (as V value is 45). My colleague suggested 1.67 index material be used in rimless for its strength. Using a small blank size will ensure thinner lenses - aspheric could be considered to thin the lens but may not be available in very small blanks.’
Yet another, ‘Lenses should be Trivex. Ideally aspheric and higher index. This will keep weight to a minimum and give the patient the best field of vision, whilst being strong and safe.’
Surprisingly few mentioned specifically a need for UV protection. And only one mentioned light reduction; ‘If the child is photophobic, I would consider prescription sunspecs or photochromic lenses.’
The suggestion from one discussant that lenticular aphakic lenses be considered (‘for aphakic lenses use lenticular lenses with as large a bowl as possible for the frame size with a UV filter’) was perhaps not really applicable in this case.