One of the most difficult challenges in myopia control is identifying whether or not patients are receiving a significant therapy benefit. This has been a problem because patients of different ages progress at varying rates, and we can never truly know how far an individual patient would have advanced if they hadn’t received treatment.

A good example of this is the typical 7-year-old non-Asian patient progressing by –1.00D in refractive error and 0.35mm in axial length per year, but the average 12-year-old non-Asian patient progresses by –0.40D in refractive error and 0.21mm in axial length per year.

Individuals of Asian descent make slightly more progress than patients of non-Asian descent. The prevalent thinking that a myope develops 0.50D per year on average only holds true for people of a specific age and racial group (those under the age of ten).

In addition, it is crucial to remember that emmetropic patients might have a neutral refractive error while still experiencing around 0.1mm of axial length advancement per year.

Recently published evidence suggests that the maximal axial length slowing experienced by a myope treated with a multifocal soft contact lens may be similar to that seen by an emmetrope in some cases.

As a result, it is unlikely that we will be able to completely halt axial length growth in children who are still growing. In addition, it is vital to remember that these are averages, which means that certain patients will progress more rapidly than the average myope.

What can we do with this information to determine the effectiveness of myopia management treatments? Efficacy is determined by observing that individuals progress less than the mean value for their age and race after undergoing a particular treatment.

While this is not a perfect sign of effectiveness, it does provide us with some foundation for determining whether a treatment is helpful, and we will most likely continue to rely on this type of data until studies that speak to the effectiveness of treatments in individual patients are conducted.

We discuss with families the potential benefits of combination therapy after at least one year of treatment. Nonetheless, it is up to the parents, after they have been educated, to decide whether or not to change the course of therapy.

Abstract

Clinical relevance: This paper provides eye care practitioners with important information about the potential side effects of 0.01% atropine.

Background: Eye care practitioners routinely administer 0.01% atropine eye drops nightly to slow the progression of myopia, but nobody has assessed accommodative lag or facility, near phoria, intraocular pressure or comfort of drop administration.

Methods: All 21- to 30-year-old adults with no history of accommodative issues or therapy were eligible. During the baseline visit, participants underwent testing related to potential side effects. Participants then administered one drop of 0.01% atropine nightly to both eyes, and all tests were repeated 1 week later.

Results: The average ± standard deviation age of the 31 participants was 23.9 ± 1.6 years, 71% were female, and 81% were Caucasian. The only significant changes were an increase in photopic pupil size from 4.9 ± 0.8 at baseline to 5.1 ± 0.6 mm after 1 week (paired sample t-test, p = 0.002) and an increase of the average intraocular pressure of the two eyes from 15.6 ± 2.7 to 16.7 ± 3.1 mmHg (paired-sample t-test, p = 0.003), but neither of these changes was clinically meaningful. There were no other statistically significant differences before and after 1-week administration of 0.01% atropine for any of the vision, accommodation, reading speed or subjective side effects. When asked how likely they would be to take the atropine drops to delay the onset of myopia on a scale from 1 (definitely not) to 10 (definitely would), participants replied with an average of 8.2 ± 2.0 after taking atropine eye drops for 1 week (paired-sample t-test, p = 0.81).

Conclusion: Nightly administration of 0.01% atropine did not result in any clinically meaningful symptoms, so patients would be very likely to take the drops to delay the onset of myopia.

Cyphers B, Huang J, Walline JJ. Symptoms and ocular findings associated with administration of 0.01% atropine in young adults. Clin Exp Optom. 2022 Feb 20:1-11. doi: 10.1080/08164622.2022.2033603. Epub ahead of print. PMID: 35188076.

https://www.tandfonline.com/doi/abs/10.1080/08164622.2022.2033603?journalCode=tceo20

The Projector Rainbow Effect can be a major annoyance to home theater owners. This is because it can significantly reduce the image quality and make the picture look blurry. In some cases, the projector rainbow effect can even be mistaken for a defect in the projector. The projector rainbow effect is visible on the projection screen as a series of red, green and blue bands that appear to be layered over each other.

In a digital light processing (DLP) projector that uses a single chip, a rotating color wheel in front of the monochromatic light source projects sequential images in different colors rapidly on the screen. The visual system of the observer combines the different colors into one image in the brain producing color motion pictures from a white light source. Unfortunately, the system is not perfect. Some individuals are not able to completely merge the different color images in their mind and individual colors are still perceived creating a “rainbow effect” around high contract images. The effect is made worse if the individual moves their eyes. Speeding up the rotation of the color wheel helps to lessen the effect but does not remove it entirely.

The reason this happens is that moving objects and colors are processed by two different parts of the visual system. The magnocellular pathway processes the movement and position of objects in the field of view and the parvocellular pathway processes the shape and color of objects in the field of view. These pathways begin in the retina eye and continue to the lateral geniculate in the thalamus portion of the brain. The retinal rod cells are more sensitive to movement and the cone cells are more sensitive to color. A slight mismatch in the signals the brain is receiving from the color pathway to the ones being received from the motion pathway lead to a perception of “rainbows”. This effect is similar to a video of someone speaking that is not exactly synced to the audio portion of them speaking.

About 40% of individuals notice this effect. This may be for several reasons; some individual may not pay attention to it, the type of media being viewed may exhibit less of the effect such a lower contrast and slower action, differing eye and brain anatomy that may have different lengths and quality of the magnocellular and parvocellular pathways and increased eye movements in some individuals when watching these projections.