Intraoperative signs of posterior capsular rupture

From EyeWiki


Posterior capsule rupture should be identified promptly in order to start proper management.[1]

Disease Entity

This is a complication of cataract surgery when the technique is done with the intention to preserve the posterior capsule in order to provide support for an intraocular lens. Therefore it is a complication of Extracapsular Catatact Extraction (ECCE) or Phacoemulsification extraction of the lens (PHACO). When the capsule is intact at the end of cataract removal, the posibility of a stable lens support is much higher, and a barrier is maintained between the anterior segment and the vitreous cavity. 

Disease

A rupture of the capsule increases the posibility of vitreous flowing in to the anterior chamber, making the removal of remaining cataract difficult. The vitreous gel occludes the aspirating cannulae and impedes adequate removal of lens fragments. If the rupture is big enough, support for the Intraoculaer Lens (IOL) can be compromised.

Etiology

The two main causes for capsule rupture are:

  • Predisposing lens and patient factors that make the capsule fragile and easy to break
  • Inadequate surgical maneuvers that produce the rupture

Risk Factors

The risk factors relating to preexisting lens conditions are:

  • Mature, white, intumescent cataract
  • 'Black' cataract
  • Posterior polar cataract
  • Age of the cataract: risk increases with the time the cataract has been present
  • Age of the patient: risk increases with age. Patients over 80s and specially 90s tend to have thinner and more fragile capsule and zonulae.
  • History of penetrating or contusive globe trauma
  • Previous vitrectomy


The risk factors relating to other conditions fo the eye that can increase the probability of a capsule rupture are:

  • Deep orbit, enopthalmos, prominent nose, that can create difficulty in surgical acces to the eye
  • Corneal opacity, specially diffuse and central because it reduces visibility
  • Shallow anterior chamber or small eye: the surgicall space for intraocular maneuver is much smaller
  • High myopia with a big eye and very deep anterior chamber
  • Pupil that dilates poorly due to posterior synechia, chronic use of miotics, diabetes, iris atrophy, or IFIS (Floppy iris syndrome)
  • Weak zonulae manifested by phacodonesis, or dislocation of the lens. Allthoug intraoperative zonular dyalisis shares  pathophysiology with capsule rupture, surgical management has some significant diferences and therefore is considered in a separate chapter.
  • Pseudoexfoliation ( small pupil or weak zonulae)
  • Anterior capsule tear


Systemic risk factors that can increase the risk of capsule rupture:

  • Inadequate anesthesia with excesive eye movements, lid pressure or head and body movement during surgery
  • Musculoskeletal alterations that impede propper positioning of the patient for surgery
  • Neurological and Mental disorders that generate involuntary movements or inadequate cooperation
  • Cardio pulmonary disease that impedes flat position of heavy breathing
  • Obesity and short neck that can produce increased vitreous pressure with shallowing of anterior chamber

General Pathology

Tear of the posterior capsule and loss of posterior support 

 

Primary prevention

Pre-operative patient assessment for any potential risk factors, advance preparation for potential challenge,

Intraoperative preparation: good positioning, may use Diamox to lower posterior pressure, use of iris ring for better dilation. Modification of surgery for the posterior polar cataract try to avoid hydrodissection step. Use of possible general anesthesia in a difficult patient.  Phacodynamic taylored to the eye and patient's condition.

Diagnosis

There are four Cardinal signs of a Torn Posterior Capsule.

  1. Sudden deepening of the anterior chamber
  2. Momentary pupillary dilatation
  3. Nucleus falls away from and will not come toward the phaco tip
  4. Vitreous aspiration into the phaco tip

History

Knowledge of past history is very crucial with any surgery.  Its important to know prior history of eye trauma, eye surgical history, history of onset of cataract and family history of early cataract to role out posterior polar, patient physical and mental history, glaucoma, iritis and respiratory habits.

Physical examination 

A comprehensive, and thorough examination is very important. External exam: looking the body and orbital shape. Patient cooperation: during examination or IOL measurement. SLE: corneal scar, anterior chamber depth, pupil size after dilation, pseudoexfoliation, phacodonesis, type and density of the cataract. Fundus exam: sign of prior surgery or any pathology/scar.

Signs

Anterior capsule tear radiating to the posterior capsule or primary posterior capsule tear.  Viterous strand in the anterior chamber or wound. Deep anterior chamber or the capsula bag with a linear line(s) on the posterior capsule  

Symptoms

The patient may not have any symptoms.   

Clinical diagnosis

It happens during surgery.  Visible tear during surgery. 

Diagnostic procedures

Visible tear, linear lines, viterous at the time of surgery.  Kenaloc can be used to check for the vitreous in the anterior chamber and at the wound site.

Laboratory test

There is no need for the lab. 

Differential diagnosis

Prior tear from trauma or surgery, posterior polar cataract with lack of capsule support, weak zonules from trauma, or pseodoexfoliation with folding of the capsule. Dense cataract with extended capsular bag with striae that appears like a linear capsular tear.

Management

The management depends on which step during the surgery the capsule is torn and the quantity of the remaining nucleus. 

The first step would be to inject a dispersive viscoelastic should be injected under the nucleus to stabilize the chamber and support the remaining nuclear material. It is imperative to not abruptly remove the phaco tip as this will depressurize the anterior chamber, risking an increase in the tear.

Once the anterior chamber is stable, the surgeon should carefully examine it for vitreous.  The other question the surgeon should consider is whether or not to convert to an ECCE.  

The decision to convert to ECCE is made on many factors including the following.

  1. Surgeon's experience with ECCE
  2. Size and constitution of nuclear fragments
  3. Size of posterior capsular tear
  4. Presence of vitreous in the anterior chamber
  5. Size of the pupil


An ECCE incision can be made in the sclera or cornea. The original corneal incision may be either enlarged for the conversion or sutured if the procedure will be continued through the sclera. The cataract is extracted using a lens loop and a muscle hook (or similar instrument).

If the anterior vitreous face is intact and not vitreous is noted in the anterior chamber, phacoemulsification may be continued.

If phacoemulsification is continued, the settings should be adjusted. Customarily, the infusion bottle height, vacuum and flow should all be lowered. The remaining nuclear material is brought to the phaco tip one at a time with the second instrument. Great care is taken to not go to foot pedal position 3 unless there is nuclear fragment on the tip. A Sheets glide may be helpful to prevent fragments from falling back through the tear.

Irrigation and aspiration of the cortex must be especially gentle at the tear may enlarge during this step. Again, the infusion bottle should be lowered. If there is only a small amount of cortex left, it can be left behind.

Location of IOL implantation will depend on the size of the tear. If there is zonular support, the sulcus is an excellent place. Anterior chamber IOLs are also popularly available. Many surgeons prefer sutured or glued IOLs.

General treatment

At the time of surgery it may require a more extensive surgical intervention. There will be a need for both dispersive, and cohesive viscoelestics, manual or phaco modified techniques, may need vitrectomy and Kenaloc injection. The lens placement may be depend on the capsular support if can be placed in the bag, sulcus or for an extensive tear and lack of support it may need anterior chamber lens.

Medical therapy

Surgical challenge that will be taking care at the time of surgery.  After surgery due to complication the patient may have elevated eye pressure which may require glaucoma drops, corneal edema may require hypertonic saline drops(Muro 128 5%).  The patient may need more frequant offfice visit untill stabllization.  The patient may need more surgery to remove residual lens products.

Medical follow up

One day post surgery, the subsequent visits it depends on the patient condition. The patient may need to come back in one week or sooner.

Surgery

Complications

Vitreous strands may be found in the anterior chamber postoperatively. It is critical to perform a careful vitrectomy followed by inspection to prevent this issue. Triessence may be helpful in identifying vitreous. If it is extruding through any of the incisions or causing macular edema, the surgeon will most likely need to return to the operating room. Lesser quantities of vitreous may be observed.

Retained nuclear material is always a concern. Intraoperative indirect retinoscopy is ideal. If the pieces are small and soft or cortical, they may be observed as many dissolve with time. The patient has to be followed for vitritis and ocular hypertension. If either of these develop or the remnant is large, then the patient will most likely need a pars plana vitrectomy and lensectomy within 2 weeks of the primary procedure.

Additional Resources

References

  1. Fishkind, William. 'The Torn Posterior Capsule: Prevention, Recognition and Management', Focal Points, June 1999, Volume XVII, Number 4