Daddy, the Hawk’s White Eye is Now Normal—Introduction to the Nictitating Membrane of a Red-Tailed Hawk

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Winter 2015 - Volume 19 Number 1

 Daddy, the Hawk's White Eye is Now Normal-

Introduction to the Nictitating Membrane of a Red-Tailed Hawk

photograph

Philip I Haigh, MD, MSc, FRCSC, FACS

Dr Haigh reports: "I was playing outside with my two kids. My eight-year-old daughter spotted a

red-tailed hawk in a tree next door. My six-year-old son ran and brought his telescope.

My daughter looked at the hawk through the telescope and told us that something was wrong

with its eye. I looked and saw its left eye was white, and I thought it was an old injury

or congenital defect! My daughter looked again and said, ‘Daddy, the hawk's eye

is perfectly normal.' So I looked, but the eye was still white. We all swapped viewing through

the telescope for several turns, and finally I noticed the left eye to be absolutely normal.

"We had discovered the nictitating membrane of a hawk—a translucent third eyelid

found in some birds, reptiles, sharks, and seals that protects and moistens the eye—as seen

covering its left eye on the bottom image. The uncovered right eye is on the top image. These two

photographs were taken by holding my iPhone lens just above the eyepiece of the telescope."

Dr Haigh is an Associate Editor of The Permanente Journal and an Oncologic and Endocrine

Surgeon at the Los Angeles Medical Center in CA.