Pregnancy and eye health

How to recognise physiological eye changes and differentiate them from major diseases

Pubblicato il

Thursday, 26 October 2017

Argomento

Ocular discomfort

Pregnancy implies a number of physiological changes essential to support and protect the foetus and prepare the woman for childbirth, these changes can affect all organs, including the eye. The changes that occur in pregnancy are commonly transient, but may occasionally be permanent.

In general, the effect of pregnancy on the ocular system can be distinguished into physiological changes and changes pathological. Pathological changes can be further subdivided into: ocular diseases that were already present before pregnancy and that change and ocular complications of systemic diseases inherent to pregnancy.

Physiological changes in the eyes during pregnancy

The most frequent ocular physiological change during gestation is theincreased pigmentation around the eyes. The brown discolouration of the face during this period is also called a gravid mask, chloasma or melasma, and is caused by increased levels of oestrogen, progesterone and melanotropic hormone (melanocyte-stimulating hormone).

Another frequently encountered condition is ptosisin which one or both upper eyelids are lowered compared to normal. Ptosis occurs in pregnancy generally in a unilateral form and is probably determined by the water retention and the hormonal changes. During gestation, a decrease in conjunctival capillaries and an increase in granularity in conjunctival venules may also occur.

Pregnancy can also affect the physiology of the tear film, resulting in thedry eye. The causes of this can be found in an increased immune reaction of the tear duct cells and the direct destruction of acinar cells by prolactin, transforming growth factor beta 1 (TGF-?1) and epidermal growth factor (EGF). The eye dryness can be further increased by dehydration due to nausea and vomiting.

During pregnancy one can also witness, especially in the final period, a reduction in corneal sensitivity. Changes in corneal curvature, oedema-related changes in corneal thickening and refractive index may occur. Changes in the cornea and tear system can also lead to contact lens intolerance. Increased curvature of the crystalline lens can also cause a shift temporary myopicThis, like the conditions described above, generally resolves spontaneously after childbirth or after breastfeeding.

An important finding reported in numerous scientific works shows that during gestation the intraocular pressure (IOP) decreases by 19.6% in women with normal IOP and by 24.4% in those with ocular hypertension. Several mechanisms have been proposed to explain this reduction in IOP, including an increase in aqueous outflow, a reduction in episcleral venous pressure due to a decrease in systemic vascular resistance, reduced scleral rigidity as a result of increased tissue elasticity, and general acidosis inherent to the gestation period.

Contrasting works, finally, report changes in the visual field. The defects highlighted include concentric and bitemporal contraction, homonymous hemianopsia and central scotoma, and the mechanism proposed to explain the onset of these visual defects is based on the increased size of the pituitary gland, which would result in its abnormal anatomical relationship with the optic chiasm.

Pathological changes in the eyes during pregnancy

Existing eye diseases that change during pregnancy

Diabetic Retinopathy (DR)

The number of women with diabetes in pregnancy is increasing due, in part, to the growing obesity of women of childbearing age. The diabetic retinopathy (DR) is the eye condition most commonly affected by pregnancy, and during this period there is an increased risk of disease development and progression.

Several scientific studies have shown that up to 50% of the non-proliferative retinopathies may worsen at the beginning of pregnancy, then improving in most cases by the third trimester and/or post-partum. Factors influencing the progression of DR are the duration of diabetes, the degree of retinopathy at conception, glycaemic levels and the coexistence of vascular disease. Gestational diabetes, on the other hand, represents a very low risk for the development of retinopathy.

It is important to emphasise that the diabetic woman's ocular health status should be assessed and stabilised before pregnancy, and glycaemic control should be strictly maintained. It would also be advisable to carry out a complete eye examination at least every trimester and within three months after delivery.

Glaucoma

Women with pre-existing glaucoma may show improvement during pregnancy, however it is important to consult the ophthalmologist early in pregnancy so that the glaucoma can be closely monitored and all treatment options discussed with the patient.

Ocular complications of systemic diseases

Preeclampsia and Eclampsia

Preeclampsia, or gestosiseclampsia can occur after the 20th week of pregnancy and is characterised by the presence of one or more clinical signs such as oedema, proteinuria or hypertension. Eclampsia, on the other hand, is the most dreaded complication of pre-eclampsia, and is characterised by convulsions, mental confusion, headaches, nausea and vomiting, and can also cause severe fetal distress.

Visual disturbancesincluding scotoma, diplopia, decreased vision and photopsia were reported in 25% of women with severe pre-eclampsia and in 50% of women with eclampsia.

The changes in pre-eclampsia-related retinopathy are similar to those in hypertensive retinopathy, the most common finding being retinal arteriolar restriction, which is usually focal but may also be generalised. Other changes include retinal haemorrhage, oedema, exudate, nerve fibre infarcts and intravitreal haemorrhage secondary to neovascularisation.

There is a positive correlation between the severity of pre-eclampsia and the degree of retinopathy, the latter, however, generally resolves at the same time as the former. Cases of retinopathy due to pre-eclampsia may be more severe if there is co-presence of diabetes, chronic hypertension and renal disease.

Sheehan's Syndrome

Sheehan syndrome, or pituitary aplopexy, is a condition characterised by enlargement of the pituitary gland due to infarction or sudden haemorrhage in pituitary adenomas. Pregnancy is one of the risk factors for this condition, which can occur due to severe post-partum haemorrhage. This syndrome is considered potentially sight-threatening, as it can cause loss of vision (52%), visual field (64%) and/or ophthalmoplegia.

Graves' disease

Graves' disease is the most common cause (85%) of hyperthyroidism during pregnancy; there may be an exacerbation of the disease in the first trimester, which tends to improve in the second and third trimesters. It is very important to monitor the postnatal period closely, as sudden recurrences of the disease have often been reported. Treatment of pregnant women with Graves' disease should be multidisciplinary and involve an obstetrician for the management of maternal medical conditions, but also an endocrinologist to monitor thehyperthyroidism and a ophthalmologist to manage ocular complications. The repercussions of Graves' disease on the eyes are common and include: fixed gaze, delayed descent of the eyelids, proptosis and extra-ocular muscle paralysis.

Uveitis

The immunosuppressive effects and high levels of steroids in pregnant women can cause an improvement in uveitis especially in mid-gestation, although there is a risk of post-partum exacerbation. The management of patients with uveitis in pregnancy, therefore, may include a decrease in the administration of uveitis medication during gestation, so as to minimise side effects on the foetus, and intensified follow-up after delivery to check for possible relapses.