Debates about whether or not to prescribe the full plus lens power found on refraction with young children are as old as the hills. Generally speaking, the higher amount of hyperopia found, and the younger the age at which it is detected, the more aggressive practitioners are in prescribing full plus. Among other clinical pearls, evidenced-based guidelines from the American Optometric Association note that: “In addition to its relationship to the development of strabismus and amblyopia, hyperopia can also affect the development of literacy skills.” Some Optometrists are therefore inclined to prescribe even low plus lens power when a child is at risk academically. On the other hand, pediatric ophthalmologists tend to downplay the need for an isometropic plus lens Rx in the absence of accommodative esotropia, even in the range of +3.00 to +6.00, as long as it is not affecting acuity or stereopsis.
I had an interesting case last week of a seven year-old girl who was referred to me by a reading specialist. Her habitual Rx was OD: +5.50 sph and OS; +6.00 sph, which she had been prescribed at age 18 months. She “lost” her glasses, and had been without them for at least a week. A few years ago she spent the entire summer without them, and after that point her pediatric ophthalmologist reportedly said they were optional. It is not uncommon for children who are over-plussed to look over their glasses as much as they look through them (the photo here is an internet image, and not my patient).
The patient’s entering unaided visual acuity was 20/60 through either eye and with both eyes together. Through her habitual Rx, acuity was reduced to 20/100 through either eye and with both together. Unaided phorias were 4^ esophoria at distance and orthophoria at near. Excellent random dot stereopsis was perceived unaided at near. Unaided NPC was to the nose. Refraction showed that distance acuity improved to 20/25 in either eye through +2.50 sph, though retinoscopy was stable in the right eye and drifted from +2.50 to +4.00 through the left eye. I found the best balance at distance and near objectively and subjectively through +3.50 OU.
It is interesting that when there is little plus found in the system, we tend to “push plus” essentially looking for either latent hyperopia or some functional improvement. Conversely, when there is gobs of plus in the system, we tend to think in the opposite direction which I describe as the “limbo stick” approach of how low we can go before there is any evidence of decrement in findings or performance.
Dr. Joe Miele has talked about the determination of a lens Rx as a negotiation between the clinician and the patient, and that is a very elegant description. In using the range of clarity concept, he illustrated shaving plus in hyperopia depending on what he patient has been habitually using prior to seeing you. In hyperopic anisometropia I have moved in the direction of best binocular balance, which is part of the process of reverse engineering hyperopia. The child in our case above has been progressively self-engineering this process by spending more and more time without her Rx. She has been doing her own version of vision therapy, and classicalists might say that she has a low enough AC/A to get away with accommodating enough to maintain a range of clarity without having to worry about accommodative esotropia.
In any event, getting away from her Rx entirely isn’t anyone’s goal at this juncture. It is more about finding the optimal lens Rx that the patient is comfortable with at distance and near, and that facilitates her being responsive to interventions to improve her reading. That is considerably less than what she has been asked to wear, but considerably more than nothing.