Chapter 26

MANAGEMENT OF EYES WITH PERFORATING INJURY

Stephen G. Schwartz and William F. Mieler

The Ocular Trauma Classification Group classified perforating ocular injuries as type D, typically involving zone III (see Chapters 1 and 2). These injuries are usually^1–11 associated with a worse outcome^a than contusions, IOFBs and penetrating trauma, and they can occasionally be as serious as ruptures. This chapter describes the unique aspects of treating eyes with injuries involving both entrance and exit wounds.

EPIDEMIOLOGY

• The incidence of perforating injuries varies widely and is reported between 7% and 31%, depending on study criteria and terminology.^1–5,7,12

Among all injured eyes undergoing vitreoretinal surgery, the incidence decreases to 4–10%.^2,3,7

If limited to injuries caused by high-speed projectiles, (e.g., industrial nail guns,¹³ BB guns,^14,15 and shotguns,^6,10,16,17), the incidence rises to 50–92%.

The rate is 0.075% among retrobulbar injections.¹⁸

Missiles are the cause in three fourths of eyes.^19,20

The following is the epidemiological information found by the USEIR.

Rate of perforating injury among all serious injuries: 3%.

Rate of perforating injury among open globe injuries: 5%.

Age (years):

• range: 2–77;

• average: 24.

Sex: 87% male.

Place of injury:

• home: 40%;

• industrial premises: 18%;

• recreation and sport: 15%;

• street and highway: 9%;

• public building: 4%.

Source of injury:

• gunshot: 38%;

• various sharp objects: 18%;

• BB/pellet gun: 17%;

• hammering on metal: 9%;

• various blunt objects: 4%;

• MVC: 3%;

• explosion: 2%.

Rate of corneo/scleral perforations^b: 53%.

Rate of sclero/scleral perforations: 47%.

PATHOPHYSIOLOGY AND PROGNOSIS

Most projectiles are blunt; some,19 but not all,³ studies report a worse prognosis associated with projectile injuries (see Table 26–1 for the muzzle velocities of projectiles causing perforating trauma).

A sharp object is able to perforate the eye at a much lower velocity, often causing less severe coincidental damage^18,20,21 unless resulting in retinal detachment, submacular hemorrhage, direct macular or optic nerve injury, or multiple posterior exit wounds (“sewing machine injury”²²).

Nails fired from an industrial nail gun^c are sharp projectiles.^d There are limited data regarding their prognosis.¹³

The damage occurring at the time of a perforating injury is compounded by scarring (i.e., consequences of the eye’s own healing response; see Chapter 8),^23–26 which is frequently far more deleterious to the eye than the initial trauma.

Contracting membranes may be present as early as 6 hours after injury.²⁶ Several factors, including blood^28–30,e and lens injury,^31,32 may contribute to the development of tractional retinal detachment.

Fibrosis, the first step in PVR, begins at the scleral wound(s). The amount of new collagen increases most dramatically between 14 and 30 days, especially in the presence of autologous blood.^33,34 The tract connecting the entry and exit wounds becomes a scaffold for fibroblast proliferation as early as 4 days after injury,³⁵ leading to anteroposterior traction.³⁶

*The velocity of a projectile is highest immediately upon being fired (muzzle velocity) and is progressively slowed by air resistance. As a reference, the estimated velocity of a BB necessary to perforate an eye consistently is 73 m/sec for the rabbit, 103 m/sec for the human, and 113 m/sec for the dog.²⁷ (It should be noted, however, that there is significant individual variability in these measurements, as BBs from a spring-loaded rifle [muzzle velocity 91 m/sec] have been documented to cause perforating injuries.¹⁶) Generally, shotgun pellets cause more severe damage than BBs because of their higher velocities. However, newer pump-action BB rifles achieve muzzle velocities approaching those of shotguns, and devastating injuries may ensue (e.g., perforating the cornea, lens, vitreous, and optic disk and coming to rest in the substance of the optic nerve 2 mm posterior to the lamina cribrosa⁷¹). A shotgun pellet may also fragment upon striking the anterior surface of the eye, resulting in multiple exit wounds.^56,57

Traumatic vitreopathy^f may make visualization more difficult; the developing partial posterior vitreous separation accentuates the anteroposterior traction between the exit wound and the vitreous base.³⁹

FIGURE 26–1 Dart injury with a posterior exit wound along the inferior vascular arcade. The patient had minimal vitreous hemorrhage, allowing direct visualization of the extent of posterior segment damage. Vision was hand motions due to development of a retinal detachment with PVR. Vitrectomy was performed with retinectomy of the incarcerated tissue, laser photocoagulation, and placement of silicone oil. Final vision was 5/200.

Timely vitrectomy1,^{9,26,35,39,42,51} serves many purposes, including:

• removal of:

clotted hyphema;

injured lens;

vitreous hemorrhage; and

IOFBs; as well as

treatment of all treatable lesions (see Figs. 26–1 through 26–4) in the posterior segment.

A meta-analysis of published reports^{1,5,11,13,15,17,19,21,22,53–58} on eyes undergoing vitrectomy for perforating trauma (excluded were series not satisfying both criteria^{2,3,4,6,7,11,52}) showed anatomical^g

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