Ординатура / Офтальмология / Английские материалы / Oxford American Handbook of Ophthalmology_Tsai, Denniston, Murray_2011

396 CHAPTER 12 Vitreoretinal

Box 12.3 Causes of macular holes

•Idiopathic

•Trauma

•CME

•Epiretinal membrane/vitreomacular traction syndrome

•Retinal detachment (rhegmatogenous)

•Laser injury

•Pathological myopia (with posterior staphyloma)

•Hypertension

•Diabetic retinopathy

SCLERAL BUCKLING PROCEDURES 399

Scleral buckling procedures

Scleral buckling

Mechanism

It is suggested that the buckle closes the break by multiple mechanisms, including moving the RPE closer to the retina and moving the retina closer to the posterior vitreous cortex. It is postulated that these may reduce flow through the break (including the amount of fluid pumped through during eye movements) and relieve vitreous traction on flap tears.

Indications

•Most simple RRD and dialysis: procedure of choice in situations where there is no pre-existing PVD, since a vitrectomy would require the induction of a PVD during surgery (highly difficult maneuver).

•Segmental buckles: for single breaks or multiple breaks within 1 clockhour.

•Encircling bands: traditionally for extensive or multiple breaks or breaks in the presence of high-risk features (e.g., aphakia/pseudophakia, etc); however the majority of these would now have a vitrectomy.

Method

•Consent: explain what the operation does and the possible complications, including failure, diplopia, refractive change, inflammation, infection, hemorrhage, explant extrusion, and worsened vision.

Perform appropriate conjunctival peritomy

•Inspect sclera for thinning and anomalous vortex veins; place traction sutures around selected rectus muscles to assist positioning.

•Identify break by indirect ophthalmoscope and indentation using the cryoprobe (or one of a number of instruments specifically designed for this purpose).

•Perform cryopexy by surrounding break(s) with a continuous ring of applications. Each application should last just long enough for the retina to whiten; the probe should not be removed until thawing has occurred. Mark the external position of the break on the sclera using indentation and a marker pen.

•Select buckle size: this should cover double the width of the retinal tear; position so that it extends from ora serrata to cover the posterior lip of the break.

•Place partial-thickness 5–0 nonabsorbable sutures using a spatulated needle. These are usually mattress-type sutures and are placed at least 1 mm away from the buckle on either side. Wider separation of sutures may result in a higher buckle. The number of sutures depends on the size of explant.

•Tighten sutures. Tighter sutures results in a higher buckle.

•Confirm buckle position is correct and that arterial perfusion of the optic nerve is unaffected.

•Close conjunctiva (e.g., with 7–0 absorbable suture).

400 CHAPTER 12 Vitreoretinal

Complications

•Intraoperative: scleral perforation, subretinal fluid (SRF) drainage problems (retinal incarceration, choroidal/subretinal hemorrhage).

•Postoperative: infection, glaucoma, extrusion, choroidal effusion/ detachment, epiretinal membrane, CME, diplopia, refractive change, diplopia.

Prognosis

Anatomical success >90%, but only around 50% achieve a VA of 20/50 (macula-on detachments).

Options

Choice of buckle

Table 12.15 Buckle options

Drainage procedures

Trans-scleral drainage of subretinal fluid with a 27–30 gauge needle is possible but is generally not necessary. This is sometimes combined with the injection of intravitreal air in the DACE (drain-air-cryotherapy-explant) procedure.

VITRECTOMY: OUTLINE 401

Vitrectomy: outline

Vitrectomy

Mechanism

Vitrectomy removes dynamic tractional forces exerted on the retina; static tractional forces arising from membranes/fibrovascular proliferation can be removed at the same time. Vitrectomy also allows access to the retina to permit drainage of subretinal fluid and insertion of tamponade agents.

Indications

Retinal detachments

•RRD: traditionally reserved for those with posterior retinal breaks, giant retinal tears, proliferative vitreoretinopathy, or media opacity; now usage is widened to include most bullous detachments, and detachments associated with aphakia/pseuodophakia (or other higherrisk features).

•TRD.

Other

•Diagnostic: e.g., biopsy for endophthalmitis, lymphoma.

•Pharmacological: e.g., administration of antibiotics, steroids.

•Macular pathology: macular holes, epiretinal membranes.

•Trauma: e.g., removal of foreign body.

•Persistent media opacity: vitreous hemorrhage, inflammatory debris, floaters (severe).

•Complications of cataract surgery: dropped nucleus, dislocated IOL.

Method

•Consent: explain what the operation does, the presence of a postoperative gas bubble, the importance of posturing, and possible complications, including failure, inflammation, infection, hemorrhage, and worsened vision.

•Make 3 sclerostomies 4 mm (phakic) or 3.5 mm (aphakic/pseudophakic) behind the limbus, placed inferotemporally, superotemporaly, and superonasally.

•Secure the infusion cannula to the inferotemporal port. The infusion is used to both maintain the globe (thus permitting aspiration) and increase pressure if intraocular bleeding occurs.

•Insert the light-pipe and then the vitrector through the two superior ports under visualization (contact lens or indirect microscope system with inverter).

•Vitrectomy: of the posterior vitreous face and extending out to the periphery.

•Replace the infusion fluid with a tamponade agent (usually gas, sometimes silicone oil for complicated cases).

•Close the sclerostomies.

•Postoperative care: advise patient regarding posturing and warn against air travel until gas is resorbed.

VITRECTOMY: HEAVY LIQUIDS AND TAMPONADE AGENTS 403

Vitrectomy: heavy liquids and tamponade agents

Perfluorocarbon (“heavy”) liquids

•Indications: these may be useful in repositioning of giant retinal tears, in flattening PVR-associated retina, in floating up dislocated lens fragments or IOLs, and in assisting hemostasis.

Agents

Perfluoro-n-octane is the most commonly used agent.

Tamponade

Indications

•Simple retinal detachment: consider air or SF6/air mix.

•Complicated retinal detachment (e.g., PVR, giant retinal tear, multiple recurrences): consider C3F8/air mix or silicone oil. Overall, these are similarly effective in PVR, although silicone oil is associated with better final VA in anterior disease, requires no postoperative posturing, and allows easier intraoperative and immediate postoperative visualization.

When vitrectomy has been performed for indications other than RD, there may be no need for tamponade.

Agents

Table 12.16 Common tamponade agents

Complications

•iIOP (may be related to overfill), posterior subcapsular “feathering” of the lens, anterior IOL movement (if pseudophakic).

Posturing

The aim of postoperative posturing by the patient is to achieve effective tamponade of the break by the gas bubble and keep the gas bubble away from the crystalline lens. Posturing should start as soon as possible (same day of surgery), for as much of each day as possible (commonly 50 min in every hour, and adopt appropriate sleeping posture), and continues for 1–2 weeks (with some variation according to tamponade agent).

The posture required will depend on the location of the retinal break but aims to move the break as superiorly as possible. Advise patient not to fly until the gas bubble has resolved.

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