Microdissection of the Rodent Eye

K. Varsha Mohan; Prakriti Sinha; Bharati Swami; Abaranjitha Muniyasamy; Perumal Nagarajan; Pramod Upadhyay

doi:10.3791/64414

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Method Article

Microdissection of the Rodent Eye

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DOI:

10.3791/64414

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April 21st, 2023

K. Varsha Mohan¹ , Prakriti Sinha¹ , Bharati Swami¹ , Abaranjitha Muniyasamy¹ , Perumal Nagarajan¹ , Pramod Upadhyay¹

¹National Institute of Immunology

Summary

This paper presents a protocol for ocular micro-dissection in rodents. The process involves the enucleation of the eyeball along with the nictitating membrane (i.e., the third eyelid). This is then followed by the separation of the posterior and anterior eye cups.

Abstract

The ocular micro-dissection of the rodent eye involves the segmentation of the enucleated eyeball with the attached nictitating membrane, or third eyelid, to obtain the anterior and posterior eyecups. With this technique, the sub-parts of the eye, including the corneal tissue, neural tissue, retinal pigment epithelial (RPE) tissue, and lens, can be obtained for wholemounts, cryo-sectioning, and/or single-cell suspensions of a specific ocular tissue. The presence of the third eyelid presents unique and significant advantages, as it benefits the maintenance of the orientation of the eye, which is important for understanding eye physiology following any localized intervention or in studies involving ocular analysis relating to the eye's spatial topography.

In this method, we enucleated the eyeball at the socket along with the third eyelid by carefully and slowly cutting through the extraocular muscles and severing the optic nerve. The eyeball was pierced through the corneal limbus using a microblade. The incision was used as the point of entry, allowing for cutting along the corneal-scleral junction by inserting micro-scissors through the incision point. Small and continuous cuts along the circumference were made until the cups separated. These could be further dissected by gently peeling the translucent layer of the neural retina using Colibri suturing forceps to obtain the neural retina and RPE layers. Further, three/four equidistant cuts were made from the periphery perpendicularly to the optic center until the optic nerve was reached. This opened the hemispherical cups into a floret shape so that they fell flat and could be easily mounted. This technique has been used in our lab for corneal wholemounts and retinal sections. The presence of the third eyelid delineates the nasal-temporal orientation, which allows for the study of various cell therapy interventions post-transplantation and, thus, the targeted physiological validation vital for visualization and accurate representation in such studies.

Introduction

Ocular dissection is an important technique in ophthalmic research and has allowed investigators to access the segments of the eye for targeted studies. Previously, ocular researchers relied on the ocular tissue from diseased individuals for their studies. However, the progressively growing number of strains of ophthalmic rodent models¹ over the years has diminished the need for human ocular tissue. These mouse strains have permitted a deeper understanding of ocular disease and interventions. Yet, they have also generated a need for innovative techniques of ocular micro-dissection. The small size and limited area of operation severely constrain....