EYE CAN NOT SEE YOU
- 3 minutes ago
- 4 min read
Tavishi
When I was fifteen, I visited the Marine Mammal Care Center for the first time. At this point, I'd already been hooked on pinnipeds, but this was my first visit to a pinniped rehabilitation centre. Upon finishing this visit, I was completely and utterly hooked.
that is the face of someone who has realized their passion for the first time.
As a sad little landlocked child (the children yearn for the seals), I would have done ANYTHING to work with pinnipeds. Because I was both a minor and an Arizonan, my opportunities were thoroughly limited; and so, I begged the Marine Mammal Care Center to let me do quite literally anything with seals.
Since then, I've designed cards, infographics, and t-shirts for the centre, and today, continue to partner with them:
https://marine-mammal-care-center-los-angeles.square.site/product/men-s-crew-neck-harbor-seal/QHDI3EWG4PZVBRN7SBFXH5R2?
When I was at the MMCC, they had this harbor seal pup named Elmer, who I remember very distinctly as one of the cutest animals I've ever seen. Anyways, a couple months later, they found out that Elmer was blind, and he was deemed nonreleasable.
Elmer now lives with two other blind seals at the Bahia Resort Hotel. Another place where they have a lot of blind seals?
The Aquarium of Niagara, where I am excited to be interning this summer!
sidebar 1: I am so lucky to be pursuing the stuff that I wanted to study as a kid. It is so cool, and it is so, so satisfying to know that I've been working towards this (see years of desperate emails) for so long. life is so wonderful!
Blindness in seals is a well recorded phenomenon; Zeehondencentrum Pieterburen monitors a blind seal in the Wadden Sea who actually functions phenomenally. Blindness and other ocular pathologies tend to be common causes of rescue in pinniped rehabilitation centres globally.
Pinnipeds have large eyes:
This is one of many features that makes them susceptible to damage, in addition to this excellent poise:
A common ocular pathology in pinnipeds is ulcerative keratopathy, found most commonly in otariids (sea lions and fur seals), rather than phocids (seals) and odobenids (walruses).
Keratopathy in pinnipeds generally involves the ulceration of the cornea, which is the transparent outer layer of the. Keratopathy begins with perilimbal edema, or an accumulation of fluid where the cornea meets the sclera (an area called the limbus). This swelling is not necessarily associated with keratopathy, but rather just a sign of ocular disturbance as a whole. Additionally, there is cloudiness and pigment in the limbus.
As keratopathy continues, pain increases, opacity worsens, and ulcers worsen. In clinics, the way corneal ulcers are spotted is fluorescein staining. If fluorescein stains fail to identify a lesion, it is either because the corneal epithelium is not penetrated, or because the cornea is penetrated significantly (exposing Descemet's membrane, etc.).
Keratopathy lesions can be identified as either stage I, stage II, or stage III based off morphology. Ulcer morphology differs by species as well.
SEA LIONS AND FUR SEALS: Stage I lesions have a little bit of cloudiness, with fluorescein staining. Stage II lesions have cloudiness in 10-20% of the cornea, with fluorescein staining. Stage III is bad, as greater than 20% of the cornea is cloudy and fluorescein is NOT staining the eye.
SEALS: whereas cloudiness is present in stage I lesions in otariids, stage I lesions in phocids presents with no cloudiness. Additionally, vascularization of the eye is more prevalent in seals rather than in sea lions and fur seals.
WALRUSES: minimal corneal cloudiness, most similar to phocid lesions
A complication of keratopathy is secondary bacterial infections, and thus, all infections are generally treated with a round of doxycycline.
Keratopathy is often caused by increased UV exposure, and can often result in loss of sight if not treated properly or quickly enough. This is why eye exams are a crucial part of any check up.
A gray seal I know well for keratopathy is Sheba from the Cornish Seal Sanctuary:
I would have loved to see Sheba in person! The Cornish Seal Sanctuary is somewhere in the UK that I hope to visit at some point, and is an amazing seal rehab centre.
Another common pinniped ocular pathology is cataract formation. Cataract formation is a natural part of the aging process in many pinnipeds, especially in captivity, but is also exacerbated by living conditions and life history.
The lens is a transparent layer of the eye meant for focusing light; a cataract is a cloudy lens, which naturally, obstructs vision. Whereas corneal ulcers can be treated via debridation and other less invasive procedures, the best solution for cataract formation is surgery.
Other than cloudiness, cataracts are also associated with lens luxations. The lens is held in place by the ciliary body, which consists of muscles, attached to the suspensory ligaments of Zinn, which are in turn, attached to the eye. These ligaments can snap, resulting in dislocation of the lens, or lens luxation. Lens luxation can cause a lot of other, more immediate issues, often leading to blindness.
The best treatment for cataracts and lens luxations is just removal of the lens as a whole, and replacement with an artificial lens. This restores vision.
The first lens surgery done on a pinniped was at the Aquarium of Niagara in 1987, on a harbor seal named Sandy!
Again, I wish I could get the opportunity to meet Sandy, but she passed away four years ago in 2022.
A large contributing factor to both keratopathy and cataract formation in pinnipeds is the environment. In captivity, it is essential that pinnipeds have adequate space, as excessive UV exposure can cause both complications.
ok bye
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