When Vision Changes Start in Pregnancy
Vision changes in pregnancy typically begin in the second trimester, with the most pronounced changes occurring in the second and third trimesters, though the specific timing depends on the underlying cause.
Physiologic Vision Changes
Normal Pregnancy-Related Changes
- Corneal and macular changes begin in the second trimester, with progressive increases through the third trimester 1, 2.
- Total macular volume and foveal retinal thickness increase significantly starting in the second trimester, with mean increases of approximately 31% and 38% respectively by the third trimester compared to the first trimester 1.
- Central corneal thickness increases by approximately 3.1% in the third trimester, accompanied by a 9.5% decrease in intraocular pressure 2.
- These physiologic changes typically resolve within 3 months postpartum 1, 2.
Mechanism of Normal Changes
- The increase in body fluid retention during pregnancy, particularly pronounced in the second and third trimesters, causes measurable changes in ocular structures 1.
- These changes are transient and generally do not cause significant visual symptoms in healthy pregnant women 3.
Pathologic Vision Changes
Diabetic Retinopathy Progression
- Women with preexisting type 1 or type 2 diabetes can experience rapid progression of diabetic retinopathy at any point during pregnancy 4, 5.
- In early pregnancy, the prevalence of any diabetic retinopathy is 52.3% and proliferative diabetic retinopathy is 6.1% 4.
- The pooled progression rate shows that 15% of women develop new diabetic retinopathy during pregnancy, and 31% experience worsening of existing nonproliferative diabetic retinopathy 4.
- Pregnancy-related retinopathy progression can begin as early as the first trimester, particularly in women with poor glycemic control at conception 4, 5.
Preeclampsia-Related Vision Changes
- Visual disturbances from preeclampsia typically occur in the second half of pregnancy, most commonly in the third trimester or peripartum period 6.
- Visual symptoms can include blurred vision, diplopia, photopsia, scotomata, and in severe cases, cortical blindness 6.
- Visual changes can be the first presenting sign of preeclampsia and require immediate evaluation 5, 6.
Critical Timing for Screening and Monitoring
Preconception and First Trimester
- Women with preexisting diabetes should undergo comprehensive dilated eye examination before pregnancy or in the first trimester to establish baseline retinal status 4, 5.
- This baseline examination is essential because pregnancy can significantly accelerate retinopathy progression 5.
Throughout Pregnancy
- Women with any level of diabetic retinopathy require monitoring every trimester and for one year postpartum 4, 5.
- More frequent monitoring is needed if rapid glycemic control is implemented, as this can paradoxically worsen retinopathy initially 4.
Important Distinction
- Women with gestational diabetes mellitus do not require eye examinations during pregnancy, as they are not at increased risk of developing diabetic retinopathy during pregnancy 4.
Clinical Pitfalls to Avoid
- Do not assume vision changes are "normal pregnancy symptoms" without proper evaluation, as they may indicate preeclampsia or diabetic retinopathy progression 5, 6.
- Do not delay ophthalmologic referral in pregnant women with diabetes who report any visual symptoms, as progression can be rapid 4, 5.
- Do not overlook the need for preconception eye examination in women with diabetes planning pregnancy, as establishing baseline retinal status is critical for monitoring progression 4.