Nonpolar Fluid Reservoir Lipids May Enable Midday Fogging in Scleral Lens Wear

Nonpolar lipids appear to be the greatest contributor to midday fogging in patients who wear scleral lenses, according to a study published in Investigative Ophthalmology & Visual Science.

Researchers enrolled neophyte scleral lens wearers (N=13; mean age, 28 years; 69% women) in the investigation and performed anterior segment optical coherence tomography (AS-OCT) to determine lens vault and midday fogging and liquid chromatography-tandem mass spectrometry to assess the fluid reservoir between the cornea and scleral lens. Participants underwent these evaluations 8 hours after initiating scleral lens wear and 8 hours following their last scheduled wear on day 4.  

At the time of dispense, the lens vault was 293 μm — settling by 81 and 88 μm after wear on days 1 and 4, respectively. The midday fogging severity on day 1 was 33 units, decreasing to 28 units on day 4. One individual demonstrated unilateral midday fogging, but all other participants had bilateral midday fogging (27%) or no fogging at all. Midday fogging status on days 1 and 4 were strongly correlated (r, 0.94; P <.001), the report shows.

The fluid reservoir samples contained a total of 170 lipids. Stratified by midday fogging experience, those with midday fog had more fatty acyls, glycerolipids, and sterols and those without fogging had more sphingolipids and glycerophospholipids. Individuals with midday fogging also had more wax esters (r, 0.73; P =.01), triacylglycerols (r, 0.64; P =.03), and cholesteryl esters (r, 0.59; P =.049) compared with participants who did not experience midday fogging. The team detected higher levels of phosphatidylcholines, phosphatidylethanolamines, and sphingomyelins among individuals who did not experience midday fogging.

“Nonpolar lipids — namely, wax esters, cholesteryl esters, and triacylglycerols — contribute to [midday fogging],” according to the researchers. “This does not rule out the presence of other contributors such as cells, proteins, metabolites, or debris.”

Study limitations include a small sample size, single center design, and failure to evaluate lipid profiles at baseline.