Vitrectomy for the Anterior Segment Surgeon

Key Points

• Cataract surgery is not without complications, which may require intraoperative vitreous management and therefore a fundamental knowledge of vitreous anatomy to achieve the best postsurgical outcomes.

• Anterior segment surgeons may encounter the need for intraoperative vitrectomy for a variety of reasons, including capsular rupture, zonular dialysis, trauma, pediatric cataract, and posterior pressure.

• Management of vitreous requires a few general principles, including maintenance of the anterior chamber, removal of as much lens material as possible, identification and excision of any vitreous prolapse, and primary implantation of a stable intraocular lens if possible. If there are any retained lens fragments, the patient may require postoperative antiinflammatory medication and prompt referral to a vitreoretinal surgeon.

Introduction

Nothing is more anxiety provoking than when the expected rapidly turns into the unexpected. Cataract surgery is one of the more frequently performed outpatient procedures in the United States. The success and rapidity of today’s planned small-incision cataract surgery depends on the development of a series of surgical maneuvers with little variation. Accordingly, nowhere else in ophthalmology is there more anxiety generated than when a routine cataract procedure is complicated by capsular rupture, vitreous loss, and posterior dislocation of the lens fragments. Although the lens fragments may be lost posteriorly and the surgeon may begin to perspire, all is not really lost. With the proper intraoperative and postoperative management, patients can have an excellent result, and the cataract surgeon’s acute management plays an important role in bringing a good outcome to fruition.

Anatomic Considerations

The vitreous is of mesenchymal embryonic origin, and the primary vitreous plays important roles in the development of the anterior segment structures. The ciliary muscle, iris vasculature, and vitreous humor are all derived from the primary vitreous. By 40 weeks’ gestational age, the primary vitreous has cleared and is optically clear with a refractive index equal to water. Not surprisingly, this complex intraocular structure is primarily composed of water. It is the hyaluronic acids and other metallomatrix proteins that account for the gelatinous nature of the vitreous, and it is this consistency that requires the vitreous be removed by excision.

The vitreous in the adult eye has a configuration similar to that of a triangle. The base of the triangle is parallel to the posterior lens surface with the apex of the triangle located at the optic nerve ( Fig. 47.1 ). There are several attachments of the vitreous body to other structures that have important implications.

• The vitreous is firmly attached to the pars plana at the vitreous base, which includes the ora serrata of the retina.

• There are also firm attachments of the vitreous to areas of lattice degeneration and chorioretinal scars, including those resulting from laser photocoagulation.

• There are moderately firm attachments to the optic nerve, macula, and the retinal vasculature.

Understanding the anatomic and biochemical properties of the vitreous plays a significant role in both the pathophysiology of disease and the surgical treatment of the retina and vitreous. Accordingly, it is alterations in these known properties of the vitreoretinal interface that often times directly result in pathologic changes and ultimately vitreoretinal diseases that have become so familiar to us.