Sight Gags by Scott Lee, OD

Finding Flaws in the Formula
Regarding AREDS2 ( “What to Do With AREDS2?” June 2013), there are two flaws in the study that I am aware of.

The researchers eliminated beta-carotene.

If the researchers used the same form of beta-carotene found in the Bausch + Lomb AREDS1 formula, they employed synthesized beta-carotene rather than the natural form of the ingredient.

Studies have shown that the natural form of beta-carotene does not have the same consequences in smokers that the synthesized ingredient causes.

Also, as for the results with fish oil, if the investigators used the ethyl ester form (the most common form) rather than the triglyceride form, their results might have been quite different.

I recommend only the triglyceride form of fish oil to my patients.

E. Michael Geiger, OD, Delray Beach, Fla.

Distinction of Dua’s Layer

We read with interest your article “More Details on Dua’s Layer of the Cornea” (July 2013) with the subtitle: “Perhaps discovered two decades ago, its meaning for primary eye care is unsure.”

In the body text of the article, one comment drew our attention: “Incidentally, Dr. Dua may not have been the first to report this layer.

A paper published in 1991 by Perry Binder, MD, describes a network of fibers located at the interface of the posterior stroma and DM, although it was not identified as a distinct corneal layer.”

Dr. Binder’s elegant work on the ultrastructure of the anterior and posterior cornea has been misquoted.

Dua’s layer is located 6μm to 15μm anterior to Descemet’s membrane.

Dr. Binder’s study reported hitherto unknown attachments between the Descemet’s membrane and the posterior stroma.1

This is a different plane to the one we have reported, which is between 6μm to 15μm anterior to the Descemet’s membrane.2

A careful read of both papers will make this distinction clear.

H.S. Dua, MD, PhD; Lana Faraj, MD, MSc; Dalia Said, MD, FRCS; Trevor Gray, MSc; James Lowe, MD, FRCPath, The University of Nottingham, Nottingham, UK

1. Binder PS, Rock ME, Schmidt KC, Anderson JA. High-voltage electron microscopy of normal human cornea. Invest Ophthalmol Vis Sci. 1991 Jul;32(8):2234-43.
2. Dua HS, Faraj LA, Said DG, Gray T, Lowe J. Human corneal anatomy redefined: a novel pre-Descemet’s layer (Dua’s layer). Ophthalmology. 2013 Sep;120(9):1778-85.