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Comparative Anatomy and Physiology of the Mammalian Eye
Published in David W. Hobson, Dermal and Ocular Toxicology, 2020
All of the common laboratory animals possess a nictitating membrane (nictitans, third eyelid). Humans possess a plica semilunaris which is a vestigial nictitating membrane. The nictitating membrane is located in the inferonasal aspect of the eye, except in birds where it is found in the superior nasal fornix. It moves passively superior and temporal across the eye as the eye is withdrawn into the orbit, displacing the bulk of the base of the third eyelid resulting in this sweeping action. Most animals possess some smooth muscle which is under autonomic innervation (sympathetic) and which may contribute to the movement of the membrane or at least its position.
Spotlight on ocular Kaposi’s sarcoma: an update on the presentation, diagnosis, and management options
Published in Expert Review of Ophthalmology, 2021
Nandini Venkateswaran, Juan C. Ramos, Adam K. Cohen, Osmel P. Alvarez, Noah K. Cohen, Anat Galor, Carol L. Karp
Conjunctival and ocular adnexal KS lesions can present either as flat lesions or elevated, fleshy, mobile masses that are bright red, dark brown, or violaceous in color with or without associated hemorrhage. Ocular KS lesions can manifest on the bulbar, tarsal, or palpebral conjunctiva including the plica semilunaris and caruncle and also develop on the eyelids and lacrimal sac. They rarely extend onto the cornea [13], invade into the orbit or involve the lacrimal gland [14]. When affecting the conjunctiva, KS most commonly involves the lower forniceal conjunctiva (Figures 1A and 2A) followed by the bulbar (Figures 2B and 3A) and upper forniceal conjunctiva [4]. With ocular surface and adnexal KS lesions, patients will often complain of foreign body sensation, irritation, or epiphora and can also report decreased vision if the lesions obstruct the visual axis.
Recovery of a Disinserted Medial Rectus Muscle after Pterygium Surgery
Published in Strabismus, 2018
Prapatsorn Patikulsila, Atitaya Apivatthakakul, Kasem Seresirikachorn
The patient had 45 prism diopters of right exotropia in the primary position. The angle of deviation increased in left gaze and decreased in right gaze. She had a marked limitation of adduction in her right eye. The eye did not surpass midline. Abduction and vertical ductions were full (Figure 1). The diagnosis of right medial rectus disinsertion was made. B-scan ultrasonography was performed, but the disinserted medial rectus could not be identified. Three weeks after the last pterygium procedure, revision surgery was performed under general anesthesia. A conjunctival incision was made just anterior to the plica semilunaris. Adherent tissue was dissected using Wescott scissors. Careful exploration of the nasal orbit was carried out and no medial rectus muscle was found at the usual location. Further exploration allowed us to find the medial rectus in a location more posteriorly in the inferonasal quadrant. The muscle was then disinserted and reattached in its original insertion site, 5 mm from limbus. The patient was still slightly exotropic, this is why the right lateral rectus was recessed 5 mm using 6-0 absorbable suture. The medial rectus muscle was disinserted and anchored to its original insertion, 5 mm from the limbus. The immediate ocular alignment was still in an exotropic position, then the lateral rectus muscle was later recessed 5 mm using 6-0 absorbable sutures.