How much does a slit-lamp breath shield protect you?

A new study attempted to replicate how well a slit-lamp breath shield and PPE help to control the spread of infected aerosol droplets.

Tell me about the study.

To simulate the doctor–patient interaction at a slit lamp, they used a mannequin to act as the doctor and a spray bottle to simulate a cough or sneeze from a patient at the slit lamp. A high-speed camera captured the respiratory droplets. They simulated three scenarios at the slit lamp:
1. Without a breath shield in place,
2. With a breath shield in place, and
3. With both a breath shield and a mask over the spray bottle.

What did they learn?

In the first and second scenarios, aerosols congregated at the highest density in the region of the doctor's nose and mouth. However, in the scenario where there was a breath shield and a mask over the spray bottle, no aerosolized particles could be observed by the high-speed camera.

The take home:

Slit-lamp breath shields provide added protection but should be used with other forms of PPE. All patients should wear face masks because of their efficacy in reducing aerosol and droplet transmission.

Legislative update

Iowa ODs now have expanded scope of practice.

With proper certification and training, optometrists in the Hawkeye State are now allowed to administer subconj injections, intralesional injections to treat chalazia, and Botox.

Conference update

Vision Expo West has been cancelled.


Will looking at a red light improve my vision?

A new pilot study published in the Journals of Gerontology says it can. CNN recently reported on this new study with the title, "Declining eyesight can be improved by looking at red light."

Let's break this study down.

The study included 12 men and 12 women ranging in age from 28 to 72. Researchers obtained baseline readings for both cone function (color contrast sensitivity) and rod function (dark adapted and retinal sensitivities were measured with the Medmont dark-adapted chromatic perimeter). Patients were asked to look at a red light (wavelength 670 nm) for 3 minutes every day in their dominant eye for 2 weeks.

What did they find?

The study researchers observed a 14% improvement in the ability to see colors (cone color contrast sensitivity) for all participants. In study participants 40 years of age or older, cone color contrast sensitivity rose by 20% over the course of the study. Rod function also significantly improved in participants 40 years of age or older.

How does this work exactly?

The role of mitochondria, which is to provide the energy for cellular function and mitochondrial function, is known to decline with age. In the retina, their density is greatest in photoreceptors, particularly cones that have high energy demands and mediate color vision. Longer wavelengths of light improve mitochondrial complex activity, thus improving the cell function.



A recent study found that patients with atopic keratoconjunctivitis were 2.25 times more likely to develop keratoconus than controls. (via)


The number of pairs of colored contact lenses that were recalled due to lack of FDA clearance. (via)


The cost for the full treatment course with Remdesivir, a treatment for COVID-19. (via)

See you next week!