Abstract

Keratopathies, cataracts, and lens luxation are well documented in pinnipeds.^1,2 In recent years at Ocean Park, Hong Kong we have noted, through improved techniques for ocular monitoring, an association between keratitis and self-resolving lens luxation. In most cases, the trainer is the first to report ocular discomfort, usually as acute blepharospasm lasting a few hours to a few days, making further assessment challenging. In these cases, an ‘acute recurrent keratitis’ was diagnosed based on the ocular examination once the blepharospasm had subsided.

Due to the ongoing recurrence of these cases, we implemented video monitoring of the eyes during the acute blepharospasm phase. Through this technique we were able to visualise the luxated lens in the anterior chamber and realised that the trainer’s report of a ‘white eye’ was incorrectly assumed to describe the corneal oedema and keratitis we saw after the blepharospasm phase.

With this knowledge we aimed to document these dynamic changes in lens position through the use of video footage and ocular ultrasound. Patients are filmed when blinking and trainers stimulate the patients to open their eyes by creating disturbances. Reviewing the video footage frame by frame allows one to appreciate the lens position. Ocular ultrasound, performed with voluntary training, allowed the lens position to be further assessed. Through the use of these techniques, we have noted a direct correlation with cases of acute keratitis and lens luxation allowing treatment of the underlying cause and not just the symptoms.

Lens removal in pinnipeds using ‘phacoemulsification via corneal incision’ requires prolonged exposure to high energy to facilitate removal, due to the hard large lens. This leads to a high complication rate, often leaving the treated eye with poor to no vision. Ocean Park has improved the success rate of cataract-removal surgery in pinnipeds, by applying a technique commonly used in humans residing in third-world countries whereby the lens is removed as a whole without the need for phacoemulsification, via a scleral approach.³ This technique has the added benefit of the patient being able to return to the water sooner due to the location of the incision on the globe and the multiple layers involved.

Despite our successes with the scleral approach, these patients still experience ongoing issues with the keratopathy secondary to the anterior lens luxation. Due to the link between cataracts and subsequent lens luxation, earlier intervention in pinnipeds and removal of the cataract before the development of keratopathies, prevents the need for ongoing chronic ocular management postoperatively and improves overall quality of life.^1,4

Acknowledgments

The authors would like to thank Dr. Rui Oliveira, for starting cataract removals at Ocean Park and helping us develop and refine the skills for the scleral approach via teleconsultations over the last 3 years.

*Presenting author

Literature Cited

1.  Colitz CM, Saville WJ, Renner MS, McBain JF, Reidarson TH, Schmitt TL, Nolan EC, Dugan SJ, Knightly F, Rodriguez MM, Mejia-Fava JC, Osborn SD, Clough PL, Collins SP, Osborn BA, Terrell K. Risk factors associated with cataracts and lens luxations in captive pinnipeds in the United States and the Bahamas. J Am Vet Med Assoc. 2010;237:429–436.

2.  Nakamura M, Matsushiro M, Tsunokawa M, Maehara S, Kooriyama T. Survey of ophthalmic disorders among captive pinnipeds in Japan. J Vet Med Sci. 2021;83(7):1075–1080.

3.  Yorston D. High-volume surgery in developing countries. Eye (Lond). 2005;19(10):1083–1089.

4.  Gelatt KN. Veterinary Ophthalmology. Fourth edition. Volume 2. Blackwell Publishing; 2007:879–881.