Protecting the Cornea During Cataract Surgery

Posted: Feb 01 2014

Protecting the Cornea During Cataract Surgery

Allon Barsam eye surgery

Fortunately with modern Phacoemulsification technology combined with proper surgical technique, corneal decompensation following cataract surgery has become very rare indeed. However there are several patient factors where corneal decompensation is more likely.

Furthermore with patients electing to have cataract surgery and refractive lens exchange at an increasingly younger age together with greater longevity it is essential for us to ensure that we protect the precious endothelial cell layer at all times to avoid the potential for an epidemic of pseudophakic bullous keratopathy (PBK) in years to come.

Patient expectation from cataract surgery also continues to increase and many of our patients expect to have perfect vision from as early as the first post-operative day. The main determinant of first day vision post cataract surgery is the extent to which the endothelium has been protected during surgery.

 

Patient factors and surgical measures to improve outcomes

Allon Barsam uses the soft shell technique in any case in which he is particularly concerned with endothelial protection. Before carrying out his capsulorhexis he places a small amount of dispersive viscoelastic (OVD) into the AC (he uses viscoat). He then places a larger amount of cohesive OVD (healon or provisc) underneath it and watches the dispersive OVD spread upwards over the endothelium. If necessary this maneuver can be repeated before starting phaco and/or before inserting the IOL. Care must be taken not to overfill with dispersive OVD before phaco as dispersive OVD conducts heat and the chances of a wound burn are higher. If necessary aspirate some OVD before commencing phaco. At the end the case he is even more careful to ensure that all OVD is aspirated due to the risk of a day one IOP spike.

The reason that he does not use the soft-shell technique in all cases is that dispersive viscoelastic commonly causes a day one IOP spike which he pre-emptively treats with oral acetozolamide but he does not feel that this is necessary in all patients. As well as the soft-shell technique, below are described a few other surgical pearls specific to different scenarios:

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  • Fuchs endothelial dystrophy: This common corneal dystrophy is characterized by central corneal guttata. Anticipating the likelihood of significant decompensation post-operatively is challenging even for the corneal specialist and in any patients in whom there are significant confluent central guttata it is prudent to seek a corneal opinion as many of us now chose to combine phacoemulsification with selective endothelial transplantation (DSAEK, DSEK, DMEK) in such cases. Allon Barsam tries and make an assessment to what extent it is the cataract and to what extent it is the guttata responsible for the patients’ symptoms but in most of these cases it is both. The advantage of the combined technique is that we are essentially pre-empting the occurrence of PBK and it is known that surgical outcomes of endothelial keratoplasty are significantly higher with Fuchs dystrophy than they are with PBK i.e. take home message is try not to wait for/ cause PBK as permanent corneal scarring/haze can ensue which does not respond as well to surgery. Having said this much more common that confluent central guttata is the appearance of early Fuchs where there are only a few guttata which are unlikely to be visually significant and in such cases it is safe to proceed carefully with Phaco using the soft shell technique.
  • Shallow Anterior Chamber: A hyperviscous OVD such as Healon GV can be helpful here to allow as much deepening of the AC as possible. Chopping the nucleus is helpful in these cases to reduce phaco energy.

Other patient factors where endothelial protection is especially important and in which he would use a soft shell technique include:

  • Dense nucleus
  • Previous surgery, especially previous corneal transplant surgery
  • Any case where greater surgical complexity/manipuation is expected, such as weak zonules and small pupils

 

 

Patient undergoing eye surgery

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Improving day one vision post cataract surgery

Eric Donnenfeld et al wrote a nice paper [1] looking at the effect of pre-operative topical steroid pulsing on endothelial protection. The theory being that the endothelial cell layer is neuroectoderm derived and as with all ‘neurological’ tissue responds more favourably to surgically induced injury when the inflammatory system is pre-emptively downregulated. The results of the paper are convincing and we have seen the effect of this regime in every day practice. The paper looks at the effect of durezol drops which are not readily available in the UK. We therefore use g. dexamethasone 0.1% and give all of our patients 4 doses of this in the one hour prior to surgery.

We continually strive to raise the bar in what can be achieved with modern cataract surgery. In order to ensure that patients achieve not only rapid visual recovery but also enjoy long term excellent vision from our surgery it is essential that we properly respect and protect the endothelial cell layer during surgery.

1. Donnenfeld ED, Holland EJ, Solomon KD, Fiore J, Gobbo A, Prince J, Sandoval HP, Shull ER, Perry HD. A multicenter randomized controlled fellow eye trial of pulse-dosed difluprednate 0.05% versus prednisolone acetate 1% in cataract surgery. Am J Ophthalmol. 2011 Oct;152(4):609-617

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