Whole Vitreous Humor Dissection for Vitreodynamic Analysis

Summary

The goal of this protocol is to show an effective technique to isolate whole, intact vitreous core and cortex from post mortem enucleated porcine eyes.

Abstract

The authors propose an effective technique to isolate whole, intact vitreous core and cortex from post mortem enucleated porcine eyes. While previous studies have shown the results of such dissections, the detailed steps have not been described, precluding researchers outside the field from replicating their methods. Other studies harvest vitreous either through aspiration, which does not maintain the vitreous structure anatomy, or through partial dissection, which only isolates the vitreous core. The proposed method isolates the whole vitreous body, with the vitreous core and cortex intact, while maintaining vitreous anatomy and structural integrity. In this method, a full thickness scleral flap in an enucleated porcine eye is first created and through this, the choroid tissue can be separated from the sclera. The scleral flap is then expanded and the choroid is completely separated from the sclera. Finally the choroid-retina tissue is peeled off the vitreous to leave an isolated intact vitreous body. The proposed vitreous dissection technique can be used to study physical properties of the vitreous humor. In particular, this method has significance for experimental studies involving drug delivery, vitreo-retinal oxygen transport, and intraocular convection.

Introduction

The goal of this method is to detail a technique to isolate a whole, intact vitreous body, with the vitreous core and cortex intact, from a cadaver eye, for the purposes of vitreodynamic analysis. As the field of vitreous physiology has grown, multi-disciplinary researchers, such as fluid mechanics researchers, are investigating the physical and biomechanical properties of the vitreous¹. To this end, it is essential to detail a technique to isolate the whole, intact vitreous body to aid multi-disciplinary researchers.

Sebag et al.² and others³ performed elegant whole vitreous dissections on human ca....

Protocol

All enucleated eyes were obtained from an abattoir and all experiments were performed in accordance with institutional biosafety laws.

1. Secure enucleated eye down on a surface. Do this by placing tissue pins through the excess tissue around the eye and securing it down into a Styrofoam board.
2. Dissect and detach perilimbal conjunctiva from eye.
   1. Use fine forceps (0.3 forceps) and microscissors (Westcott scissors) to incise the conjunctiva at the limbus and bluntly dissect it off the sclera. Cut the conjunctiva along the limbus as the blunt dissection proceeds to allow further dissection.
   2. Remove conjunctiva all the way around....

Results

Following the protocol will lead to a successful vitreous dissection with the core and cortex (Figure 3) intact. This is evident from the residual pieces of retina adhered to the vitreous cortex. Intact whole vitreous humor can be used in several ways for specific vitreodynamic experiments. In our case, the diffusion rate of oxygen in intact vitreous humor and it’s corresponding time constant was studied (Figure 2). Vitreous that was dissected (core and cortex) using our method was place.......

Discussion

There are two critical steps that must be carefully performed during vitreous dissection. Step 3, creating a full thickness scleral flap, is crucial to the entire dissection. Care should be taken to not cut into the choroid when creating the full thickness scleral flap. The other critical step is dissecting away the sclera from the choroid. This step must be carefully done to prevent creating multiple holes in the choroid from which the vitreous can spill out. There is a way to modify the protocol and still dissect intac.......

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
0.3 forceps	Storz Opthalmics	E1793
Westcott Tenotomy Scissors Curved Right	Storz Opthalmics	E3320 R
Scalpel Handle No. 3	VWR	25607-947
Scalpel Blade, #11, for #3 Handle	VWR	470174-844