Investigation Supports Allegations of "Disastrous and Sickening" Results of Lens Experiments Sponsored By Animalens, Inc. on Laying Hens
United Poultry Concerns (UPC) undertook to investigate the use of permanent red plastic contact lenses in laying hens upon receiving two written complaints from employees in the poultry unit at California Polytechnic State University, San Luis Obispo, one of which was dated April 15, 1991. The complaints charged that a lens experiment conducted by a senior student on hens at Cal Poly was causing severe eye infections, abnormal behavior, and blindness, and preventing the hens from closing their eyes normally because the lenses were so large. Hens were "pecking at the air" and "rubbing their eyes repeatedly on their wings." A June 6, 1991 article on the experiment in the school newspaper, The Mustang Daily, quoted another student employee who stated that the lenses cause "a lot of infections in the hens' eyes" which worsen progressively with time. An attached photograph, taken by senior staff writer, David Bock, showed a severely debeaked hen whose left eye appeared to have dissolved under the lens.

The student experiment at Cal Poly is now officially over to our knowledge. Future experiments are said not to be planned or the lenses to be recommended for commercial use. In January 1992, about 400 of the original 1,000 hens were estimated to remain in the poultry unit waiting to be "phased out," i.e., sent to slaughter. Contacts with school official initiated by UPC and Action for Animals' Rights (AFAR), a group based in Atascadero, CA, have not, in our opinion, resulted in a responsible show of concern for the welfare and suffering of the hens. For example, during the experiment the hens did not receive, nor do they now receive, veterinary care and treatment of their eyes, according to our sources of information.

In July 1991, a concerned citizen removed several of the experimental hens from the poultry unit at Cal Poly. Photographs were taken of the hens in the unit and of those who were removed. The hens were taken to Dr. Nedim C. Buyukmihci, V.M.D., Associate Professor of Ophthalmology in the School of Veterinary Medicine at the University of California, Davis. Dr. Buyukmihci's July 25, 1991 report on his examination of these hens supports his earlier one based on his examination of a pair of lenses. He explains that "The red plastic lenses are at the very least uncomfortable for the chickens. These red plastic lenses also appear to cause corneal ulcers. In the worst case, these ulcers can rupture and lead to blindness. Pain always is a significant component of corneal ulcers or ruptured eyes."

Dr. Buyukmihci also expressed concern over the fact that these non-biodegradable lenses are to be disposed of by being ground up along with the chickens' heads, which means they would be recycled back into farm animal and pet food. This could present serious health, safety, and environmental hazards, particularly in large-scale production.


The Animal Behavior Control (ABL-1) red plastic contact lens for chickens, manufactured by Animalens, Inc. of Wellesley, MA, is designed to boost egg industry profits by reducing aggressive behavior in laying hens resulting from genetic manipulation for high egg production exacerbated by tight caging and overcrowding of hens. What the industry calls "cannibalism" in chickens is in fact a distortion of their natural behavior. By nature, chickens are active social creatures with complexly sensitive beaks and eyes adaptively correlated for foraging and a wide range of other activities. Modern housing frustrates this natural repertoire resulting in "vices" like "cannibalism" in which chickens peck each other to death. The industry responds by amputating part of the chicken's beak with a hot cauterizing blade at birth. Not surprisingly, this procedure does not alleviate the suffering that causes "economically significant" morbidity and mortality in overcrowded flocks. Animalens, Inc. promotes the ABL-1 contact lens as a supplement to, and eventually perhaps a substitute for, debeaking (euphemistically termed "beak trimming" by the poultry industry). They claim the lenses "calm" the hens by making everything appear the color of blood. Lensed hens do not lay more eggs but they allegedly convert food "more efficiently," thereby saving feed costs.

Problems with the Lenses

The red plastic lenses are made of non-gas permeable molded material: they do not breathe or allow the eye to breathe, that is, to receive oxygen. Studies of extended-wear lenses in humans show that oxygen deficiency from continuous wear of these lenses causes corneal ulceration and increased opportunity for microbial contamination. A study published in the September 21, 1989 issue of The New England Journal of Medicine (Vol 321, No. 12) on the risk of corneal ulceration infection in users of extended-wear, gas permeable soft contact lenses led the FDA to request manufacturers (May 30, 1989) to recommend a maximum wearing time of 1 to 7 days and to strengthen warnings on the risk of corneal disease while urging proper care of lenses.

Animalens asserts that unlike the human lens which lies directly on the cornea, the chicken lens sits above the nictitating membrane (the chicken's third eyelid which helps keep the eye clean and moist) and that properly inserted, the lens does not touch the cornea. Professor A.T. Leighton Jr. of Virginia Polytechnic Institute, who took part in developing the technology for Animalens, told UPC that as long as the nictitating membrane moves freely beneath the lens, the eye receives sufficient oxygen, stays moist, and does not receive corneal damage.

However, Dr. Buyukmihci observed in his report of January 14, 1992 that this assertion is "much at odds with available information about the functional limitations of the bird's nictitating membrane." He explains:

A major function of this structure is to sweep across the cornea, cleaning it and redistributing the tear film. It is very thin and not vascularized sufficiently to be a primary source of oxygen, so it matters not that it may be below the contact lens. Moreover, its contact with the cornea is only for a fraction of a second several times a minute; at all other times it is tucked away in the corner of the eye nearer the beak. In order for it to be a significant provider of oxygen, it would have to remain in contact with the cornea for a relatively considerable period of time, especially because of its relatively poor blood supply (compared with the alveoli of the lungs, for example). There is little possibility that its brief contact with the cornea could result in any significant oxygenation. A major source of oxygen for the cornea is through the absorption of this gas from the air by tears, something not efficiently possible with the contact lens in place.
The nictitating membrane itself does not provide moisture to the eye. There are tear producing glands near or distant to the membrane that provide the moisture, depending upon the species. In any event, I do not think this is a factor in this discussion. I believe the physical trauma caused by the presence of the lens, the bacterial colonization of microscopic wounds produced and the reduction in oxygen are critical issues.

Another serious difficulty associated with the use of the lenses is the high ammonia, low oxygen content of the typical commercial poultry environment caused by overcrowding and excremental build-up. In this atmosphere, chickens can develop ammonia burns, a keratoconjunctivitis caused by exposure to ammonia fumes produced from unsanitary conditions. Afflicted birds rub their heads and eyes on their wings and let out cries of pain. They stay quiet in one spot with closed eyelids and stop eating. They go blind. Thus, the indwelling oxygen deficiency of the lens is exacerbated by the oxygen- deficient environment the chickens would be forced to live in.

Animalens' claim that chickens with contact lenses are "calm" shows scientific naivete at best. In chronic pain, discomfort, or distress, chickens and other organisms, including humans, tend to acclimate to the chronic noxious stimulus showing only very subtle outward signs of pain. They reduce their activities, develop guarding behavior, and may even deteriorate to a state of learned helplessness indicating that they have succumbed utterly to helpless despair and the destruction of their personality and will.

Asked to comment upon the use of the lenses in commercial production environments, poultry scientists, including Paul Siegel, Andrew Yersin, Frank Edens, Eldon Kienholz, and Joy Mench, have expressed reservations summarized as follows: 1. The bird could not remove the dust, feathers, or other particles (common in production environments) that could become trapped under the lens; 2. The dusty ammonia-laden atmosphere would probably cause considerable infection; 3. The lens would often be incorrectly fitted by the handler, forced by economic considerations to work fast. Improperly fitted lenses would shift to the side causing even more problems and, in some cases, lenses have been known to be mistakenly placed beneath the nictitating membrane; 4. The nictitating membrane is not enough to relieve the irritation of having a foreign object in the eye for a whole year, or to keep out all the dust; 5. The lens would have to be uniformly smooth or rough edges could catch on the nictitating membrane; 6. Chickens in commercial environments need to develop a stable social structure to reduce tensions and nonadaptive energy expenditure requiring visual recognition and memory; the lenses would effectively discourage this; 7. The real problem is specialized breeding for aggressive birds plus too many birds per cage. The answer is to breed for less aggressive traits and give birds more room in cages, or to put them on the floor with ample room or quit exploiting chickens altogether.

Incredibly, Animalens, Inc. asserts that the lenses can be installed in the naked eyes of chickens "by unskilled labor." When UPC asked 3 Animalens- sponsored researchers and 1 production manager whether the lenses, once installed, were ever removed for treatment or veterinary examination to their knowledge, the answer was uniformly, "No." Robert Spiller, the principal researcher in the student experiment at Cal Poly, even wrote, "Once the lenses have been installed, it is not possible to remove them without damaging the bird's eyes." However, Dr. Buyukmihci states, "This simply is untrue." He writes:

When I first saw the photographs of the lenses in place and examined the lenses, I, too, thought that removal would be problematical. Since then, however, I have had the opportunity to examine personally several hens with the red contact lenses in place. Although I had to be careful, it was relatively easy for me to remove the lenses in every case using various fine eye forceps. As I have relayed to you previously, there had been considerable damage already present in some of the eyes. Removal of the lenses did not further traumatize the eyes.


As is debeaking, the contact lens for chickens is an abusive substitute for the proper care and housing of these birds. If the birds were properly cared for there would be no need for the lens. In addition, the lens experiment at Cal Poly reveals the nadir that can be reached by researchers and others whom the government of society has so far failed to make accountable for their actions: the student protocol approved by Robert Spiller for "Field trial with red contact lenses for laying hens" does not even contain a requirement for the veterinary care and treatment of the sensitive eyes of living creatures being used in so intimate and destructive a fashion. To date the egg industry has not adopted contact lenses for laying hens, nor should they. This narrowly opportunistic technology is a benighted way for a university, a company or an industry to make a buck.
Also see the Spring '96 Poultry Press where Mike Royko, the well-known syndicated columnist with the Chicago Tribune, revised his stance on the use of contact lenses for chickens.
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