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Getting to grips with ocular tissue
is crucial to PK success in children
Ana Hidalgo-Simón MD, PhD
in Gatwick
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| Same
child two years post-bilateral PKP. The child has alternating
esotropia. |
A PROPER understanding of the child subject’s ocular tissues
is crucial to success with paediatric penetrating keratoplasty (PK),
reported consultant ophthalmic surgeon Ken K Nischal FRCOphth at
a conference of cornea specialists.
Mr Nischal presented his team’s experience using the technique
with children over the last three years. His unit performs tectonic
procedures when it is necessary to maintain the integrity of the
globe because corneoscleral perforation is imminent or has occurred,
as well as therapeutic procedures.
His group performed five tectonic corneal grafts between August
1999 and September 2002. Two patients had Peter’s anomaly
spontaneous cornea rupture and three had descemetoceles. The surgeons
also performed an additional two tectonic scleral patch grafts to
treat scleral melts.
Mr Nischal and colleagues also performed three deep anterior lamellar
keratoplasties in children with mucopolysaccharidoses. All were
performed using high frequency ultrasound guidance.
In these cases, air is not visible in the anterior chamber because
the cornea is very hazy. The team used ultrasound to measure corneal
thickness. After using the Barron-Hessburg trephination system,
they introduced air into the anterior chamber to visualise the interface.
During the same period, the unit performed 19 therapeutic PKs. Some
74% of these involved cases of Peter’s anomaly or sclerocornea.
All cases presented iridocorneal adhesions and the mean age of the
children was 18 months.
Indications for PK included the presence of visually inhibiting
pathologies or bilateral involvement. When only one eye was affected
the operation was carried out if the child suffered from a particular
type of Peter’s anomaly, where there is thinning of the central
cornea or the ‘good’ eye is considered abnormal. Prospective
patients undergo comprehensive preoperative work-ups, which include
the use of electrodiagnostics, conventional ocular ultrasound and
high frequency ultrasound.
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| Peters'
anomaly |
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“All
children undergo comprehensive preoperative assessment, but only
after considerable counselling of the parents is this type of surgery
offered,” Mr Nischal emphasised.
Follow-up of these cases ranges from one month to three years, with
a mean of 17.6 months. Clear graft survival with or without medical
rescue currently runs at 13/19 (68%) for therapeutic PK. For Peter’s
anomaly or sclerocornea, survival is slightly lower at 8/14 (57%).
Glaucoma was observed only in three cases, all with Peter’s
anomaly, Mr Nischal said.
He stressed that careful surgery, meticulous postoperative follow-up
and intensive preoperative counselling facilitates the best chance
of successful paediatric keratoplasty but warned that the management
of these cases is very labour intensive.
“During the first six weeks, infants and neonates need to
be seen twice a week. And there is no guarantee of good results.
As long as the parents understand the risk of rejection and the
possibility of things going wrong, but still want to attempt treatment,
the operation should be offered to them,” Mr Nischal said.
Ken K Nischal FRCOphth
Great Ormond Street Hospital for Children, London, UK
Email: kkn@btinternet.com
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