What are the standard surgical steps in pars plana vitrectomy with silicone oil insertion for retinal detachment?

Standard Surgical Steps in Pars Plana Vitrectomy with Silicone Oil Insertion for Retinal Detachment

Pars plana vitrectomy with silicone oil tamponade for retinal detachment follows a systematic sequence: port creation, core vitrectomy, posterior vitreous detachment induction, peripheral vitreous removal with examination for breaks, endolaser or cryotherapy to all retinal breaks, fluid-air exchange, and silicone oil injection to achieve complete fill.

Pre-operative Preparation

Anesthesia Selection

• Monitored anesthesia care with local anesthetic is the standard approach, though general anesthesia can be used for anxious or claustrophobic patients 1.
• If general anesthesia is used, avoid nitrous oxide during at least the last 10 minutes of fluid-air exchange to prevent unpredictable gas fill complications 1.

Lens Management

• Combined phacoemulsification should be performed if the patient is phakic, as cataract formation is inevitable with silicone oil tamponade 2, 3.
• Cataract occurs in 100% of phakic eyes when silicone oil is not removed within 6 months 2.

Surgical Technique

Port Creation and Vitrectomy

• Create standard 3-port pars plana access using 23-, 25-, or 27-gauge instrumentation 1.
• Perform core vitrectomy to remove the central vitreous gel 1.
• Inject triamcinolone acetonide following core vitrectomy to highlight the posterior vitreous and facilitate visualization 1.

Posterior Vitreous Detachment

• Induce complete posterior vitreous detachment by separating the posterior cortical hyaloid from the retinal surface, particularly over the macula 1.
• Use aspiration, an illuminated pick, or forceps to create the separation 1.
• Extend vitreous removal anteriorly to at least the equator with thorough peripheral vitreous shaving 1.

Retinal Break Management

• Perform meticulous intraoperative examination of the peripheral retina for all breaks or tears prior to fluid-air exchange 1.
• This step is critical as iatrogenic retinal breaks develop frequently during posterior vitreous detachment creation 1.
• Apply endolaser or cryotherapy to completely surround all retinal breaks 4.
• Treatment must extend anteriorly to the ora serrata if tears cannot be completely surrounded 4.
• Pay particular attention to the anterior border of horseshoe tears, as inadequate treatment here is the most common site of failure 4.

Membrane Peeling (If Present)

• Remove epiretinal membranes and internal limiting membrane if present to release all tractional elements from the macula 1.
• Use forceps, microvitreoretinal blade, or other instruments to elevate and peel membranes 1.

Fluid-Air Exchange and Silicone Oil Injection

• Perform complete fluid-air exchange to remove all subretinal and intraocular fluid 1.
• Inject silicone oil through the sclerotomy to achieve complete fill of the vitreous cavity 2, 3.
• The oil viscosity choice (1000cs vs 5000cs) depends on the clinical scenario, though 5000cs oil is associated with significantly higher postoperative intraocular pressure 5.

Sclerotomy Closure

• Close all sclerotomies meticulously with mattress sutures using long scleral passes to prevent hypotony 1.
• The sclerotomy should be straight rather than chevron-shaped and directed perpendicular to the sclera 1.
• Dry and thoroughly check the sutured wound for leakage—do not assume small amounts of oozing will resolve spontaneously 1.

Critical Pitfalls to Avoid

Inadequate Peripheral Treatment

• Insufficient anterior extension of laser/cryotherapy to the ora serrata is a significant risk factor for surgical failure 4.
• The chorioretinal adhesion from cryotherapy is not firm for up to 1 month, during which vitreous traction can pull tears beyond the treated area 4.

Incomplete Vitreous Removal

• Inadequate peripheral vitreous shaving leaves residual traction that can cause recurrent detachment 2, 3.
• Early recurrences (within 6 months) and late recurrences (12-18 months) occur in a substantial proportion of cases 2.

Sclerotomy Complications

• Hypotony from inadequate sclerotomy closure is one of the most common surgical complications 1.
• If postoperative hypotony occurs, close follow-up with pressure patching may be sufficient if no other serious adverse signs are present 1.

Expected Complications and Monitoring

Intraocular Pressure Elevation

• Ocular hypertension develops in approximately 67% of patients with long-term silicone oil tamponade 5.
• IOP elevation is significantly higher with 5000cs oil compared to 1000cs oil 5.
• Elevated IOP responds poorly to medical or surgical treatment in many cases 2.

Retinal Toxicity

• Silicone oil causes significant reduction in ganglion cell layer-inner plexiform layer thickness and is associated with vision deterioration 6.
• This toxic effect on the ganglion cell complex contributes to incomplete visual recovery despite anatomical success 6.

Other Complications

• Corneal edema, conjunctival hyperemia, and uveitis occur less frequently 2.
• Keratopathy from silicone oil emulsification and anterior chamber migration occurs in 7-12% of cases 5.
• Epiretinal membrane formation and recurrent retinal detachment remain significant risks 5.