Myopia Progession
Race as a predictor of myopia progression in paediatric patients
Summary
Myopia has multi-factorial causes with both nature and nurture contributing. The ‘nurture’ causes are ones we can attempt to control, but ‘nature’ causes need careful investigation if we are to confidentially pick out those at greater risk.
The authors used a retrospective cohort study to examine any differences in progression rate with different ethnicities and greater understand who may be at increased risk of myopic progression.
Study outcomes revealed differences in myopic progression over time between the different racial groups, with the East/Southeast and South Asian children having higher myopia and their myopia progressing faster compared to the white children
Clinical relevance
Allowing for different sample sizes and inclusion criteria, results from other studies have made similar race/ethnicity links with myopia prevalence.
- A CHASE study conducted in the UK in 2010 found that children of South Asian descent showed the highest prevalence of myopia compared to other race/ethnicity such as black African Caribbean and white children.1
- The Sydney Myopia Study found that the East Asian children in their random sample had a higher prevalence of myopia.2
For everyday myopic management practice, the findings from this study into the relationship between race and myopia reminds us that certain children will benefit from effective intervention as early as possible, especially if we are aware they may progress faster than other racial groups.
Limitations and future research
- Meeting abstract so not fully peer-reviewed
- Race distribution: Latino children were over represented at 54%, compared to 15% white, 9% black, 9% East/Southeastern Asian and 2% South Asian.
- Children’s ages: The children’s age range for the study was 5-11 yrs, suggesting primary school age.
- It would be interesting to see what the rates of progression were beyond 11yrs, perhaps into the late teens.
- A second study could explore if there is a different stabilising age for each racial group and if progression is influenced by a change in studying or physical activities with increasing age and if race still came into play at that stage.
- Parents refractive error and genetic link: The children were grouped for analysis according to their stated race/ethnicity and language spoken as this was the main aim of the study.
- The abstract doesn’t state if the refractive status of the parents was included too. It can be helpful to know this when assessing a child’s likelihood of myopia and could provide an extra confirmation of their risk.
- The confirmation of racial susceptibility to myopia from Fong et al may also demonstrate the genetic aspect to myopia.
- There can be a 6-fold increased risk of a child being myopic if both parents are also myopic.3
- Contributing factors: The results, understandably, were adjusted for confounding factors such as screen time and outdoor activities to help isolate any racial link.
- Knowing how likely each factor could either increase progression (e.g, prolonged near work) or slow progression (e.g, time spent outdoors) alongside the racial link and societal/cultural differences would help complete an overall picture.
- Society/culture differences: Once a correlation between a given race and the risk of myopia is established, the next step could be to consider why this occurs for given groups.
- Educational expectations, socio-economic factors, the physical environment of the country of residence and the opportunity for outdoor sports activities have been well discussed previously.
Axial Length
Scleral Cross-Linking Using Rose Bengal Green Light
Summary
The sclera is at risk of deformation due to increasing axial length progression. The suggestion is that by strengthening the sclera using cross-linking treatment, this could help resist the traction caused by axial elongation and therefore reduce myopia progression. Cross-linking treatment using riboflavin drops and UV light is already being used for the treatment of corneal ectasia, such as keratoconus, to help strengthen the bonds between the collagen fibrils and resist IOP forces.
This research aimed to discover if the same treatment could be used on the sclera to similar effect using Rose Bengal and green light (RGX).
Clinical relevance
There are a few positives that we can gather from this research:
Scleral cross-linking could be an option for future myopia intervention. The results show that it may be possible to target certain areas of the sclera for treatment to help limit axial length increase.
Riboflavin is known to be cytotoxic and Rose Bengal has been shown to be less so – this is encouraging news as less cellular irritation can mean better healing.
However, the investigation was carried out in-vitro with the strips of tissue samples removed from enucleated porcine globes and although the results are very promising and informative, further research will need to show us how this will translate to a viable in-vivo human treatment!
Limitations and future research
- Surgical risks.
- Elsheikh and Philips (1) discussed cross-linking using riboflavin and UVA light in their paper in 2013 and raised concerns of the exposure of the scleral tissue during the procedure and the cytotoxic risk to the retina. Although Lopez et al were using Rose Bengal and green light instead, the process of any operation and risk to the retina is likely to be similar regardless of the substances used, even when Rose Bengal carries less of a toxicity issue.
- Another option?
- Elsheikh and Philips also suggested from their research that chemical cross-linking might be an alternative approach using glyceraldehyde that had shown to give a 150% stiffness increase in the sclera with no toxicity risk.
- Would other timings make a difference?
- The ARVO abstract video was a summary of the experimentation and therefore didn’t explain the reasons for choosing the immersion time for the strips in the Rose Bengal, or why a given time of green light exposure was chosen.
- Are these the optimum immersion and light exposure times for maximum effect, or could different timings give better results?
- Is one area enough?
- The research showed conclusively that the RGX treatment was most effective in the posterior temporal regions. Would this be enough on its own to resist deformation?
- When could this be done and who for?
- Further information would be needed as to the best time to undertake this procedure, and who it would be for.
- Presumably, it would be more effective if carried out before any rapid changes in myopic refraction have taken place (i.e, a child who has been diagnosed with myopia and who is identified as being in a higher risk group for progression).
- It may be too little too late if they are left to progress before considering it. However, we would have to be very sure of any growth and progression information we had before suggesting any operation which carries risks.
- Like any surgery, the benefits would have to outweigh the risks.
Those of us involved in everyday myopia management will need to continue to use whatever options we have at our disposal for now while this remains a ‘Tomorrow’s World’ possibility.
Multifocal Contact Lenses
BLINK Study Results: Comparing +1.50 Vs +2.50 Add Multifocal Contact Lenses For Myopia Control
Summary
- +1.50D centre distance design did not significantly slow myopia progression or axial eye elongation relative to the single vision control
- The reported 43% slower myopia progression with +2.50D centre distance multifocal meets the following criteria for being considered clinically meaningful:
- International Myopia Institute (>40% reduction)1
- Workshop organised by the US Food and Drug Administration (FDA, >30%)2
- The previously reported 3 year study on MiSight reported 59% less myopia and 52% reduction in axial eye growth relative to single vision controls3
- Only 35 adverse responses were reported with none indicated as being serious or causing permanent discontinuation of CL wear
Clinical relevance
- Centre distance CooperVision Biofinity multifocal lenses with a +2.50D slow progression of myopia (43%) and axial eye growth (36%) over three years relative to single vision CLs.
- While the reported myopia control effect is less than previously reported for CooperVision MiSight, the outcomes of this study suggest that +2.50 centre distance Biofinity multifocal lenses offer a useful myopia control alternative:
- for regions where MiSight is not available
- MiSight is available but off label prescribing is a consideration (MiSight is FDA approved for myopia control in the USA, the centre distance Biofinity is not FDA approved in the USA)
- The low level of adverse events provides evidence towards monthly soft contact lenses being a safe option for children to wear
Limitations and future research
- Adjusted myopia progression of the SV (control) was slower than reported for other US based studies4-7
- Only examined +1.50 and +2.50D adds - does not answer whether higher add powers than +2.50 create a better myopia control effect
- The authors report that the control group in the MiSight study exhibited higher myopia progression (-1.24D) than the control group in the current centre distance multifocal study (-1.01D)
- however, the same 0.62mm change to axial length was reported for the control group in both studies, which suggests that valid comparisons between the two studies can be made
Vision With Multifocal Contact Lenses In Myopes And Presbyopes
Summary
Influence of centre near (CN) design multifocal lenses (1-day Acuvue Moist) on visual acuity was measured in young adults and presbyopes under cyclopegic and natural conditions with the effect of different pupil sizes modelled using an adaptive optics system. Overall the lenses performed similarly at improving near VA between cyclopleged young adults and presbyopes when compared to no lenses, and created no apparent difference to near VA in accommodating young adults, however there was slight degradation to distance VA.
Clinical relevance
Centre near design multifocal lenses, when fit to young adults in add powers up to +2.50 do not appear to reduce visual acuity at near, however there appeared slight degradation to VA at distance when compared to the without multifocal lenses condition.
Limitations and future research
- Meeting abstract so not fully peer-reviewed
- Statistics are not included in the abstract and no error bars are displayed on the presented charts to hep infer significance of findings - consequently outcomes can only be considered as observational.
- Young adults examined so can only infer if the same outcomes would be found in children.
- Outcomes from centre distance designs would be interesting to know for comparison.
Influence Of Centre Near Design Multifocal CLs On Visual Acuity In Young Myopes And Presbyopes
Summary
Influence of centre near (CN) design multifocal lenses (1-day Acuvue Moist) on visual acuity was measured in young adults and presbyopes under cyclopegic and natural conditions with the effect of different pupil sizes modelled using an adaptive optics system. Overall the lenses performed similarly at improving near VA between cyclopleged young adults and presbyopes when compared to no lenses, and created no apparent difference to near VA in accommodating young adults, however there was slight degradation to distance VA.
Clinical relevance
Centre near design multifocal lenses, when fit to young adults in add powers up to +2.50 do not appear to reduce visual acuity at near, however there appeared slight degradation to VA at distance when compared to the without multifocal lenses condition.
Limitations and future research
- Meeting abstract so not fully peer-reviewed
- Statistics are not included in the abstract and no error bars are displayed on the presented charts to hep infer significance of findings - consequently outcomes can only be considered as observational
- Young adults examined so can only infer if the same outcomes would be found in children
- Outcomes from centre distance designs would be interesting to know for comparison
Orthokeratology
Effect Of High Add Orthokeratology Lens Designs On Corneal Hysteresis And Ocular Aberrations
Summary
Orthokeratology lenses designed to create a high add do not alter corneal hysteresis (rigidity) in up to 1 month of wear but increase higher order aberrations, mainly coma and spherical aberration.
Clinical relevance
OK lenses designed to target higher add power do not alter corneal rigidity and were found by participants to not induce daytime haloes or glare.
Limitations and future research
- Meeting abstract so not fully peer-reviewed
- Statistics are not included in the abstract or to presentation to define significance of findings - consequently, despite likely obvious change in measurements in some cases (ocular aberrations) reported outcomes should be considered as observational
- Pupil diameter used for measuring higher order aberrations is not defined
- Ocular aberrations alter as a function of pupil diameter, which in the absence of knowing pupil diameter makes it difficult to interpret possible influence of the presented values
- No comparison to standard OK lens designs to determine differences
- Long term studies needed to ascertain whether customised high add designs create a greater myopia control effect than standard OK lens designs as speculated in the poster conclusions
