September 8, 2021

The most important ophthalmology research updates, delivered directly to you.

In this week's issue

Female sex was associated with increased risk of severe axial elongation in high myopia; older age may be protective
Congenital toxoplasmosis and its ocular findings were most common for mothers infected during their third trimester
High-fat diet and hyperlipidemia may be associated with meibomian gland dysfunction
Plus a new type of corneal prosthetic in Cornea and racial disparities in DR screening in Pediatrics

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Parasite: Not Just a Movie - Congenital Toxoplasmosis Following an Outbreak

Ophthalmology

Remember the toxoplasmosis cats from Sketchy? Well, they’ve moved to Brazil. From March to November 2018, a large, likely waterborne, outbreak of Toxoplasmosis gondii was reported in southern Brazil. Recently, researchers analyzed ocular and neural sequelae seen among 187 infected infants born in the affected region during this period to mothers with confirmed T. gondii infection. Congenital toxoplasmosis was confirmed in 29 (15.5%) of these infants, 19 of whom had ocular abnormalities. Among the 38 affected eyes, the abnormalities seen included: retinochoroiditis (76.3%), optic nerve abnormalities (13.2%), microphthalmia (2.6%), and cataract (5.3%). Additionally, 13 (7.2%) of screened infants had cerebral calcifications, another symptom of congenital toxoplasmosis, with incidence of cerebral calcifications being higher among infants with ocular abnormalities. The researchers also found the rate of congenital toxoplasmosis to be higher among infants born to mothers infected during the third trimester, highlighting the importance of maternal screening for T. gondii infection during pregnancy, especially in the setting of a known outbreak.

Risk factors for axial elongation in patients with high or pathologic myopia

JAMA Ophthalmology

There’s more to nearsightedness than meets the eye. If you have myopia, you might want to set your glasses aside to read the fine print. Nearsightedness is usually a benign condition, requiring nothing more than glasses or contact lenses to achieve excellent vision. However, patients with severe myopia have an increased risk of complications including open-angle glaucoma, cataract, retinal tear and detachment, and myopic macular degeneration. These complications and myopia itself may be associated with elongation of the visual axis; the eye becomes more oval instead of spherical. The axial length can continue to grow in patients with high or pathologic myopia, thus increasing the risk of complications over time. In a retrospective cohort study of 1,877 adult patients with high or pathologic myopia, investigators studied risk factors for axial elongation using measurements from 9,161 visits. Multivariable logistic regression analysis revealed an increase in the odds of severe axis elongation associated with female sex (OR 1.46, 95% CI 1.38-1.55), best-corrected visual acuity worse than 20/400 (OR 1.33, 95% CI 1.15-1.54), and prior choroidal neovascularization (OR 1.37, 95% CI 1.29-1.47). Increased age appeared to have a protective effect against axial elongation. Compared to patients aged 20-30 years old (reference category), for patients over age 80 had a 56% reduced odds of axis elongation. This may represent progressive stabilization of eye morphology with time. Overall, this study characterizes the risk of axis elongation associated with various non-modifiable risk factors. Understanding these factors may have implications for stratifying risk and counseling patients concerned about progressive refractive error or complications of high myopia.

High-fat diet negatively impacts meibomian gland health

IOVS

We often want to lower cholesterol for the sake of heart health, but did you know that it could also help your eyes? The effects of high cholesterol, triglycerides, and other lipid abnormalities due to hyperlipidemia on ocular health and disease are relatively underexplored. In this current study, researchers sought to define the effects of high-fat diet (HFD) on meibomian glands using a mouse model of hyperlipidemia. Mice were fed a high fat diet that resulted in elevated cholesterol levels similar to those found in humans with moderate hyperlipidemia. Meibomian glands (MG) were evaluated histologically and biochemically for inflammation, cytokines, acini cell apoptosis, and mitochondrial damage. HFD-induced hyperlipidemia promoted periglandular MG inflammation mediated through MAPK/NFκB signaling leading to increased inflammatory infiltrates and cytokines. Hyperlipidemia concurrently downregulated PPAR-γ signaling. Overall, these changes led to accumulated lipids in MG acini, increased acini cell apoptosis and mitochondrial damage. Shifting to standard diet or treatment with rosiglitazone (PPAR- γ agonist) was able to reverse some of these effects. The signaling pathways involved could also serve as potential therapeutic targets for meibomian gland disease (MGD) due to hyperlipidemia. While these findings are limited to a mouse model, it provides substantial evidence for the negative impacts of hyperlipidemia on meibomian gland health that could impair vision function. So, yes, reducing fats in your diet will make not only your heart happy but your eyes, too!

Cornea & Refractive Surgery

Is the novel CorNeat KPro for corneal transplantation clinically promising?

Cornea

Silly Rabbit! Leave the transplants to the KPros! Can this joke get any cornea? The purpose of this study from Israel was to evaluate the feasibility and long-term integration of the CorNeat KPro in rabbits! Today, a corneal keratoprosthesis (KPro) is used as a last resort to treat corneal blindness given the risks of postoperative retroprosthetic membrane, corneal melt, limited retention, postoperative glaucoma, and overall poor visual quality. Previous KPros were designed to integrate with remaining, diseased corneal tissue. The CorNeat KPro is a novel synthetic corneal with its skirt implanted under the highly vascular conjunctiva for optimal integration and retention. New Zealand White rabbits (n = 8) were implanted unilaterally with this KPro and observed for 6 months and were monitored with a slit-lamp exam. One rabbit developed postoperative endophthalmitis and was removed from the study. Eyes were enucleated and evaluated histologically to assess tissue integration and inflammatory response. There was a retention rate of 87.5% of the CorNeat KPro at 6-month follow-up. The only inflammatory indicators were mild conjunctival and iridial congestion. There was comparable presence of fibroblasts with collagen fibrils in all eyes, and some mild foreign body reaction was observed. Thus, this study finds that the surgical procedure and long-term integration of CorNeat KPro may be a clinically promising intervention for humans in the future!

Pediatrics

Racial disparities among youth with diabetic retinopathy screening

JAMA Ophthalmology

Racial minority groups make up a larger population of diabetic retinopathy patients, but are often not receiving the adequate screening recommendations. As the leading cause of blindness in youths, diabetic retinopathy is a serious disease entity that needs to be screened and managed thoroughly. Youths diagnosed with type 1 or type 2 diabetes are recommended by the American Diabetes Association to have quarterly screening diabetic retinopathy; however adherence to this strict schedule remains low, especially among minority groups. This cohort study enrolled 149 patients with diabetes and sought to further evaluate demographics between patients who did and did not have previous diabetic eye exams and assess barriers to receiving adequate screening via chart analysis and self-reported patient questionnaires. Of the patients with no reported prior eye exam, the majority of them were non-White, had type 2 diabetes, had public insurance or Medicaid, lower household income, and had parents with lower education status. Further analysis of barriers to screening revealed transportation issues, cost of medical fees, difficulty finding time, and not recalling the recommendation for the eye exam. As minority youths are less likely to receive diabetic eye exams and more likely to have diabetic retinopathy, it is imperative to clearly explain screening guidelines and personally address future barriers these patients may face.

Question of the Week

A 2-month-old girl is referred to the ophthalmology clinic by her pediatrician because one of her eyes appears smaller than the other. She has a history of infantile seizures. Her vitals today are within normal limits. Her fundus exam is shown below.

What additional abnormality is she most likely to have?
A. Absence of corpus callosum on MRI
B. Mutated gene on chromosome 22
C. Neuronal Lipofuscin deposits
D. ELISA positive for toxocara antibodies

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