Pregnancy and Your Eyes

We all know that during pregnancy, a woman's body goes through a great deal of change hormonally and physiologically.  But did you know her eyes change as well?  Below are some of the most common effects pregnancy can have on the eye.

  • Corneal changes. In some cases, pregnancy can cause the cornea, the front window of the eye, to change curvature and even swell, leading to shifts in glasses and contact lens prescriptions. In addition, changes in the chemistry of the tear film can lead to dry eyes and contact lens intolerance. It is for these reasons that it is generally not recommended to have any new contact lens fitting or new glasses prescription checks until several months postpartum. We want to get the most accurate measurements possible.
  • Retinal changes.  Many different conditions can affect the retina during pregnancy. If the pregnant woman has diabetes, diabetic eye disease can progress by 50%. In women with preeclampsia, a condition where blood pressure rises significantly, over 40% of women can show changes in the retinal blood vessels, and 25% to 50% complain of changes to their vision.
  • Eye Pressure Fluctuation.  Intraocular pressure (IOP) usually decreases during pregnancy. The exact mechanism causing this is unknown, but it is usually attributed to an increase of flow of intraocular fluid out of the eye. This is good news for pregnant women with glaucoma or high IOP. In fact, the drop in IOP is larger when you start with a high IOP compared to one in the normal range.

There are many more effects that pregnancy can have on the eye, but these are the most common. One other thing to keep in mind is that though the likelihood of any adverse effect is extremely low, we try not to use any diagnostic eye drops on pregnant patients during the eye exam. Unless there is a medical necessity to dilate the pupils or check IOP, it is a good rule of thumb to put off using drops until after the patient has given birth in order to protect the developing baby.  

Detecting Alzheimer's though an Eye Exam?

Alzheimer's Disease International estimates that the number of people living with dementia worldwide - nearly 44 million in 2014 - will almost double by 2030 and more than triple by 2050.

There is no single test that can show if a person has Alzheimer's, but doctors can almost always determine if a person has dementia, although it may be difficult to determine the exact cause. Diagnosing Alzheimer's requires careful medical evaluation, neurological testing, and sometimes brain imaging and blood tests to rule out other causes of dementia.

Most of the testing for early disease - MRI scans of the brain, brain PET scans looking for amyloid, and spinal taps looking for certain proteins in the spinal fluid - are not very accurate, and they are invasive and often expensive.

Researchers have now turned to findings in the eye to help with early detection and are hoping to find ways to make the diagnosis earlier when potential treatments may have a better outcome. There is also hope that these tests will be less expensive and invasive then the other options.

One of the tests that has shown promise is an OCT of the retina. Almost every eye doctor’s office already has an OCT, and so if this research proves fruitful, the test could be done relatively cheaply because there is not a need to buy more expensive equipment. Right now, the average OCT exam is reimbursed at about the $50 per exam level, much less than the cost of an MRI or PET Scan.

Neuroscientists at the Gladstone Institutes in San Francisco showed a proof of concept in frontotemporal dementia, which is like Alzheimer’s but attacks much earlier and accounts for just 10% to 15% of dementia cases. They found that patients with frontotemporal dementia had thinning of the neuron layer of the retina on OCT.

In a study at Moorfields Eye Hospital they also found that people who had a thinner layer of neurons in the macula on an OCT exam were more likely to perform poorly on the cognitive tests - a clear warning sign they may be undergoing the early stages of dementia.

Study leader Dr. Fang Ko, said: “Our findings show a clear association between thinner macular retinal nerve fiber layer and poor cognition in the study population. This provides a possible new biomarker for studies of neurodegeneration.”

A second marker that is getting a careful look is identifying the presence of amyloid in the eye. Amyloid, thought to be one of the key causes of Alzheimer’s, which makes up most dementia cases, is often found to have formed into clumps and plaques in the brain. Scientists at Waterloo University in Canada found people with severe Alzheimer’s disease had deposits of a protein amyloid on their retinas.

Research conducted at Lifespan-Rhode Island Hospital in Providence co-led by Peter Snyder, a professor of neurology at Brown University, and Cláudia Santos, a graduate student at the University of Rhode Island, is attempting to detect amyloid in the retina by OCT and follows people over time to see if the amyloid increases and if it correlates with cognitive impairment.

Another angle being pursued by a company called Cognoptix is looking for amyloid in the lens of the eye. Using Cognoptix's SAPPHIRE II system, which detects amyloid in the lens, a 40-person Phase 2 clinical trial was conducted at four sites. The study recruited patients who were clinically diagnosed with probable Alzheimer’s disease (AD) via a rigorous neuropsychological and imaging workup. The study, using age-matched healthy controls, showed outstanding results of 85% sensitivity, and 95% specificity in predicting which people had probable AD.

The company is now planning a Phase 3 study that must show a strong correlation in a bigger study group to obtain ultimate FDA approval.

One of the other items I was going to include in this post was information on what visual symptoms occur in dementia patients and how family and friends can support them but I found an outstanding review already available online by the Alzheimer’s society that covers all those points. If you have a loved one with dementia this is an excellent read and I highly recommend you take the time to review it.

 

Article contributed by Dr. Brian Wnorowski, M.D.

This blog provides general information and discussion about eye health and related subjects. The words and other content provided in this blog, and in any linked materials, are not intended and should not be construed as medical advice. If the reader or any other person has a medical concern, he or she should consult with an appropriately licensed physician. The content of this blog cannot be reproduced or duplicated without the express written consent of Eye IQ.