FP240 : A Novel Use of Vitrectomy Trocar for Safer Capsulorrhexis in Intumescent Cataract.

Dr. Shashi Nath Jha, S4140, Dr. Anjani Khanna, Dr. Neeraj Manchanda, Dr. Nidhi Panwar

ABSTRACT

We describe a technique of using a small-gauge (23/25G), single, sutureless  transconjunctival pars plana sclerotomy to ease  phacoemulsification in eyes with a shallow anterior chamber and high intraocular pressure (phacomorphic glaucoma and following fluid misdirection syndrome). These eyes owing to positive vitreous pressure are prone to various intraoperative complications particularly during phacoemulsification which is relieved by single sclerotomy.

KEY WORDS

Sutureless; transconjunctival; shallow anterior chamber; high intraocular pressure; phacomorphic glaucoma; fluid misdirection syndrome; positive vitreous pressure

Word counts- Abstract – 58, Text-1041, References-133, Legends-50

Phacoemulsification in eyes with a shallow anterior chamber and high intraocular pressure (IOP) may pose a challenge to the surgeon. A larger lens, a shorter axial length (hypermetropic eyes) or a combination of both may predispose such eyes to a positive vitreous pressure; also, the formation of anterior chamber with an ophthalmic viscosurgical device (OVD) may not provide enough room to perform phacoemulsification. There is an increased risk of capsulorhexis tears extending into the periphery, iris prolapse, corneal decompensation and suprachoroidal hemorrhage during cataract surgery.

Cataract extraction and lowering of intraocular pressure is the only definitive treatment for an intumescent cataract. Various techniques have been described to deepen the anterior chamber in such eyes prior to phacoemulsification. Pars plana vitreous tap¹, a mechanized cutter², as described by Chang, small-gauge pars plana limited vitrectomy ³ , modified controlled anterior chamber paracentesis⁴ etc . The aim of all these techniques is to lower the intraoperative intraocular pressure/vitreous pressure.

PATIENTS AND METHODS

In an interventional case series of ten patients, we made a small-gauge(23/25 G ), single, sutureless  transconjunctival pars plana sclerotomy in the inferonasal quadrant using a 23/25 G Eckardt trocar cannula to allow controlled egress of vitreous, thereby gradually reducing the intraoperative IOP during phacoemulsification.

Preoperative Evaluation

Preoperative evaluation included slitlamp examination, visual acuity and corneal curvature measurement. Intraocular pressure (IOP) was assessed by noncontact tonometry. A Bscan was performed to examine the vitreous body and retina. The axial length (AL), lens thickness, and anterior chamber depth (ACD) were measured by A-scan.

SURGICAL TECHNIQUE

1. Small gauge (23/25G) single sutureless transconjunctival sclerotomy is made using a trocar cannula . Surgery is performed by a single surgeon under peribulbar anesthesia. A trocar (23/25 G) cannula is used to make a single sclerotomy transconjunctivally, 3.5 mm posterior to the limbus through the pars plana inferonasally. This allows for sustained and controlled flow of vitreous, thereby decompressing and softening the eye in a gradual manner intraoperatively, and thus avoiding the risk of expulsive haemorrhage.(Figure1.) An OVD is injected simultaneously to deepen the anterior chamber through a clear corneal side-port incision. Either high viscosity sodium hyaluronate 1.4% (Healon GV) or a soft-shell technique using sodium hyaluronate 3.0%–chondroitin sulfate 4.0% (Viscoat) or just a viscodispersive agent in case of non-availability of former is used.
2. Phacoemulsification of the nucleus. Lens extraction using phacoemulsification is performed through a temporal clear corneal incision. In anticipation of weak zonules, pressurizing the anterior chamber is mandatory to counter the outward expansive forces of the intumescent and swollen capsular bag. The anterior capsule is then stained with trypan blue to facilitate capsulorrhexis. To begin with a smaller diameter rhexis is made, which is enlarged with forceps once its proper control is established. Phacoemulsification is performed using the standard stop-and-chop nucleotomy procedure followed by automated irrigation/aspiration of the cortical matter and insertion of a foldable acrylic intraocular lens in the capsular bag. (Figure2.)
3. The 23/25 G trocar is then removed and pressure is applied over the scleral opening for about 30 seconds. The natural elasticity of the sclera approximates the sclerotomy wound thereby obviating the need for suturing.(Figure3.)

RESULTS

The technique was used in ten cases of phacomorphic glaucoma with successful results and no immediate post operative complications. Visual acuity improved in all the patients (mean final visual acuity 6/9 and IOP reduction of 10±4 mm Hg with mean post op IOP 12±2 mm Hg. No intra-operative or post operative complications related to the technique were noted.

DISCUSSION

Problems frequently encountered in phacoemulsification of eyes with intumescent cataract causing phacomorphic glaucoma are increased iris-instrument contact causing intra-operative pupillary constriction due to shallow angle, severe corneal edema, intraocular inflammation, and efflux of hydrated cortex when the capsule is punctured . Also the anterior lens capsule is more convex and the absence of the red reflex makes its localization difficult, thereby making control of the capsulorhexis difficult , with increased chances of its extension to the periphery and thus posterior capsule rupture.⁵ Moreover the risk for endothelial cell loss is greater owing to the close proximity of the phaco tip during nucleus emulsification and the reduced endothelial reserve in these patients. Recently the success rates of CCC has increased with the use of dim operative lighting, high power operative microscopes, ophthalmic viscosurgical devices (OVDs), aspiration of the hydrated cortex, and anterior capsular staining with trypan blue dye. Also, Arshinoff’s soft-shell technique, which combines the advantages of a high molecular weight viscoelastic (to deepen the chamber) and dispersive viscoelastic ( to protect corneal endothelial cells) has increased the safety of phacoemulsification in such eyes⁶ Overt injection of any OVD to deepen the anterior chamber should however be avoided as it may lead to excessive IOP elevation with worsening of corneal edema and iris prolapse.

The use of a sutureless, small-gauge, pars plana sclerotomy is another effective technique to overcome these problems. The controlled and gradual debulking of the anterior vitreous, leads to posterior displacement of the lens, deepening the anterior chamber and thereby facilitating surgical manipulations within the chamber. Also the IOP is lowered, decreasing the positive vitreous pressure and reducing the chance of capsulorhexis extension, posterior capsule rupture, iris prolapse, and intraoperative suprachoroidal hemorrhage.

Thus, an uneventful phacoemulsification along with foldable IOL implantation is possible, with decreased risk for damaging the corneal endothelium.

The limitation of this technique is a small risk of port site dialysis, retinal break/tear, and retinal detachment, as reported after small-gauge vitrectomy for other posterior segment disorders, which can be taken care of by a regular  indirect ophthalmoscopic examination postoperatively.

To conclude, sutureless single port pars plana sclerotomy is a safe, effective  and relatively fast technique which can cause controlled reduction of IOP peroperatively, thereby reducing complication rate in phacoemulsification in difficult situations.

WHAT WAS KNOWN

Phacoemulsification is very risky in patients with shallow anterior chamber with intumescent cataract and those with phacomorphic glaucoma. Various techniques have been described in such scenarios with variable results.

WHAT THIS PAPER ADDS

The usage of a single  sutureless, small-gauge, pars plana sclerotomy for phacoemulsification of intumescent cataracts can aid in reducing the chance of capsulorhexis extension, posterior capsule rupture, iris prolapse, and intraoperative suprachoroidal hemorrhage.

None of the authors have any conflicts of interest

None of the authors have any financial disclosures

REFERENCES

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