Does pregnancy influence myopia?

HWN presented this case involving a 32-year-old woman whose myopia onset after having her first child and had progressed since. So, the question to the Myopia Profile community was, “Does pregnancy have anything to do with adult-onset myopia?"

The community have suggested that cycloplegic refraction and binocular vision tests are needed as one eye was shown to progress more than the other. This is useful to rule out refractive error changes due to accommodative function.

As the patient expressed the desire to be glasses-free, Ortho K and soft multifocal contact lenses were suggested. As there are currently no studies looking into the efficacy of myopia control strategies in adult age groups, it is important that the patient understands that the purpose of fitting Ortho K is to primarily provide clear vision, with any myopia control effects being a bonus.

The studies on adult onset myopia are limited, with one finding that one-third of myopia commenced in adulthood in a Caucasian twin population. Myopia reported in that study was low to moderate.²

Adult myopia progression, though, is quite common. The longest follow up on this is a series of studies from Finland, which showed that mean myopia progression in the 20's decade was -0.45 D ± 0.71 (SD): in 45% of cases, progression was ≥0.5 D and in 18% of cases, myopia increased by ≥1.00 D.³

According to some studies, some pregnant women may experience a myopic shift during their pregnancy, possibly due to changes in corneal thickness or lens curvature.^4,5 In such cases, refractive error tends to return to pre-pregnancy level after delivery.^5,6 On the other hand, another study suggests that pregnancy is inversely associated with myopia progression, whereby pregnant women are less likely to progress than their non-pregnant counterparts.⁷

Pregnancy can also lead to contact lens intolerance due to dry eye problems caused by disruption of lacrimal acinar cells.⁴ Therefore, spectacles may be a better option in such cases during pregnancy.

These ocular changes usually resolve in postpartum. Both contact lens and spectacle option are acceptable options, depending on the mother’s preference. Consider with a mother of an infant that she will need to wake up during the night to feed the baby, so the practicalities of Ortho K may not suit.

Some from the community surmised that the myopic progression could potentially be attributed to the increased screen time whilst breastfeeding. This is a possibility as frequent near work at close distances is identified to be a risk factor of adult myopia progression.¹ 

In this case, however, it's important to note that the patient reported myopia onset after pregnancy, and progression in the six years since. The immediate influence of hormonal changes, potential screentime while breastfeeding and even concerns of fitting Ortho K to a mother of an infant are unlikely factors in this case. Hence the interesting aspects of this case are firstly the influence of pregnancy in onset, and the best choices to attempt to manage young adult myopia progression.

• It is not uncommon for refractive error and contact lens tolerance to change during pregnancy. Pregnancy-induced changes tend to resolve spontaneously after delivery. Therefore, it is important to ensure that a pregnant patient has functional visual acuity, keeping in mind that any changes may return to pre-pregnancy levels postpartum.
• Preference for spectacle or contact lens treatments may change during pregnancy and postpartum due to changes in the mother’s ocular physiology (e.g. pregnancy-related dry eyes) and lifestyle (e.g. waking up in the middle of the night).
• It is important to communicate the lack of evidence on the efficacy of current myopia control strategies in adult myopia progression. Contact lens options are likely going to be the best choice for adult progressing myopes to correct vision, while potentially controlling myopia progression.
• Young adult myopia progression does occur - by around 0.50D on average across the decade of the 20s, but in around 20% of young myopes this progression could be more than 1D.
• When in doubt, cycloplegic refraction and axial length measurements can help corroborate your findings and rule out accommodative involvement in myopia progression.