Lenticular sclerosis, also called nuclear sclerosis, appears as a greying of the lens of the eye. Most commonly pet owners first see it when light hits a pet’s eyes just right and some of the light is reflected back, cloudiness appearing through the pupil.
Lenticular sclerosis is caused by the natural lens hardening process that occurs as part of aging. It’s the same thing that causes humans’ “arms to be too short” around age 40. As the lens ages it becomes firmer. The firmer it gets, the more difficult it is for the lens’ muscles to reshape it, resulting in people being less able to focus up close. Reading glasses are the next step for us.
Dogs already have poor accommodation (ability to focus) so they aren’t bothered by being unable to read. Besides, they have a different use for the newspaper.
Nuclear sclerosis occurs because the lens of the eye continues to create new fibers inside its capsule for a lifetime. The capsule will not expand significantly, so old fibers become compressed in the center of the lens by the addition of new fibers. Therefore, the greying effect is worst at the center (nucleus) of the lens.
Lenticular sclerosis is not a cataract. To the naked eye they look very similar. Furthermore, when ophthalmologists for humans perform cataract surgery, they are most commonly removed sclerotic lenses, not cataractous ones, even though patient and physician alike may refer to it as “cataract surgery.” It’s just simpler. In addition, we humans need our accommodation to perform our daily functions.
Lenticular sclerosis causes no adverse effect on vision in the earliest stages. Later, as cloudiness becomes heavier, vision in low-light conditions may become less acute. Cataract formation can occur at the same time, resulting in a lens so cloudy that vision is completely lost. For those patients, cataract surgery is an option.
See you tomorrow, Dr. Randolph.