Endophthalmitis is a devastating potential consequence of any ocular surgery or trauma. Although it is a rare complication after cataract surgery, occurring at a rate of 0.04% to 0.2%,¹ endophthalmitis can lead to serious complications, including retinal detachment, total blindness, loss of the eye, glaucoma, and hypotony.

While the rate of endophthalmitis following intravitreal injection is lower, ranging from 0.049% to 0.056%, the severity and outcomes are generally worse than in cases following cataract surgery.² As the combined rate of cataract surgery and intravitreal injections has increased in the last 10 years, I have noted that the incidence of endophthalmitis requiring vitrectomy has also increased.

Patients presenting with confirmed or suspected endophthalmitis require immediate attention. An immediate decision to perform a tap and inject or to proceed directly to vitrectomy must be made. The Early Vitrectomy Study showed a slightly better outcome with pars plana vitrectomy in the worst cases but that “routine immediate vitrectomy is not necessary in patients with hand motion or better vision at presentation.”³

Infection related to intravitreal injections often occurs more acutely in terms of onset, typically within 1 to 3 days, compared to cataract surgery, which occurs within 5 to 7 days. Patients who are treated early or who have less aggressive endophthalmitis tended to do equally well if they received intravitreal injections or vitrectomy.

However, in cases with endophthalmitis related to trabeculectomy, intravitreal injections, or trauma, the tendency is toward poorer outcomes regardless of the action taken compared to infections arising from cataract surgery. In these situations, vitrectomy from the onset maximizes our ability to stabilize the eye, restore vision, and preserve the eye itself in terms of anatomical health.

Endophthalmitis related to intravitreal injections tends to be associated with more virulent organisms, including Streptococcus species, compared to post-cataract surgery infections. Therefore, in infections related to intravitreal injections, trabeculectomy, trauma, or an endogenous source, even if the vision is counting fingers, I strongly consider immediate vitrectomy because the disease course tends to be more aggressive and destructive. In the more common cases associated with cataract surgery that have counting-fingers vision, I tend to tap and inject initially, with close observation.

ENDOSCOPIC VITRECTOMY VS STANDARD

The inflammatory component of endophthalmitis, in addition to the infective agent, plays a major role in the ultimate toxic effects on the eye, including vasculitis, retinal necrosis, optic neuritis, membrane formation, tractional retinal detachment, and primary hypotony. Even if antibiotics successfully kill the organism, continual ocular damage can occur from the inflammatory debris, comprised of endotoxins, exotoxins, cell wall, and immune response components.

The purpose and goal of vitrectomy in the setting of endophthalmitis are to mitigate the inflammatory and infectious damage by debulking purulent material within the eye. I have performed a number of traditional vitrectomy procedures, which are very challenging due to a compromised anterior chamber, often with reduced corneal clarity that results in limited visualization of the posterior segment.

In most cases of vitrectomy utilizing a wide-angle visualization system only, the limited view of the posterior segment prevents a thorough vitrectomy. Most surgeons perform sufficient vitrectomy to enable visualization of the posterior pole, leaving behind a significant amount of anterior vitreous. This residual vitreous is nearly always opacified from purulent material and prevents a thorough examination of the peripheral retina for tears. The residual vitreous also serves as a scaffold for future membrane formation, leading to retinal and ciliary body traction.

Endoscopic vitrectomy dramatically improves the ability to perform a thorough removal of vitreous and residual debris. Endoscopy provides increased capacity to see not only posterior-segment structures that are normally visible with wide-angle visualization systems but also the pars plana, ciliary body, and anterior vitreous base with membrane formation, where vitreous opacification is the most significant.

Additionally, endoscopy in cases of endophthalmitis allows for successful treatment of related complications, such as retinal tears and detachment, vitreous hemorrhage, intraocular foreign bodies, and dislocated implanted materials. Without endoscopy, the treatment of these complications becomes nearly impossible in the primary surgery, and it often requires additional procedures after visualization has improved. This additional procedure often leads to worse outcomes.

TECHNIQUE

I use the Endo Optiks endoscopy system (BVI) system for all cases of endophthalmitis. I prefer to use a 23-gauge vitrectomy system in the majority of such cases, placing the ports in the traditional positions, between 3 mm and 4 mm posterior to the limbus.

Correct infusion placement is verified prior to activation using direct visualization with the endoscope. Although more challenging, this verification can also be performed in phakic eyes without causing lens touch. If infusion placement cannot be verified, I place the infusion using a 23-gauge trocar into the inferior anterior chamber.

Once the infusion is activated and the pressure is stabilized, the anterior chamber is addressed. Corneal scraping is necessary in most cases to remove edematous, opacified epithelium. Pupillary membranes with associated hypopyon are removed through a paracentesis, using an irrigation cannula or intraocular forceps. Attention is then turned to the posterior-segment portion of the surgery. If needed, the anterior-chamber infusion is repositioned to the pars plans, or simply kept in place.

Vitrectomy for endophthalmitis is similar in technique to endoscopic vitrectomy in other cases. The goal is always to keep the vitrector in close view and in close proximity to the endoscope to reduce inadvertent trauma to structures such as the iris or retina. I debulk the central core vitreous first to create a clear space and then proceed to the peripheral vitreous starting inferiorly.

If the patient is phakic, careful depression helps to avoid lens touching while allowing for more complete vitreous removal. In pseudophakic patients, we can move more freely and be very aggressive using the endoscope to perform a complete vitrectomy.

The typical goal is to clearly visualize the optic nerve, macula, and the midperipheral retina in the posterior segment and to repair or confirm that no tears are present. In pseudophakic eyes, the anterior vitreous is removed to allow visualization of the ciliary body in at least 3 quadrants.

In severe cases of endophthalmitis, hypotony is of greater concern due to delayed traction and detachment of the anterior ciliary body or ciliary body shutdown. In my opinion, a thorough vitrectomy that removes the debris from the anterior vitreous may reduce the chance of primary ciliary body shutdown and tractional detachment.

In most cases, I use the endoscope to perform an air-fluid exchange. This maneuver allows for a more complete removal of debris, and in my personal experience, it is nearly impossible without the endoscope.

In addition, for more severe cases of endophthalmitis, it is my practice to instill silicone oil to potentially reduce the risk of postoperative hypotony and to improve vision and visualization. Silicone oil is very helpful for short-term stabilization of the eye, and it reduces vitreous opacification from debris in the immediate postop period.

This strategy is similar to that used in diabetic patients, in whom silicone oil helps to improve vision and visualization from recurrent vitreous hemorrhage. Although using silicone oil does require an additional surgery at a future time, it is not, in my opinion, of major consequence.

SEEING IS BELIEVING

There is no question that endoscopic vitrectomy is extremely helpful and perhaps critical in cases of endophthalmitis. The ability to visualize from an endoscope and a wide-angle system is a major advantage that must be experienced to be fully appreciated. My goal for endophthalmitis has changed from cautious debulking to thorough removal of the vitreous, allowing for almost complete visualization of the posterior segment, which would not be possible without the endoscope.

With proper utilization, the endoscope allows not only for a more thorough vitrectomy but also for a more complete evaluation and treatment of retinal pathology. This ability ultimately leads to faster and better visual recovery and reduced postoperative complications. RP

REFERENCES

1. Packer M, Chang DF, Dewey SH. Prevention, diagnosis, and management of acute postoperative bacterial endophthalmitis. J Cataract Refract Surg. 2011;37(9):1699-1714.
2. Fileta JB, Scott IU, Flynn HW Jr. Meta-analysis of infectious endophthalmitis after intravitreal injection of anti-vascular endothelial growth factor agents. Ophthalmic Surg Lasers Imaging Retina. 2014;45(2):143-149.
3. Results of the Endophthalmitis Vitrectomy Study. A randomized trial of immediate vitrectomy and of intravenous antibiotics for the treatment of postoperative bacterial endophthalmitis. Endophthalmitis Vitrectomy Study Group. Arch Ophthalmol. 1995;113(12):1479-1496.