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January 2003
IN THIS ISSUE

Long-term SLT results promise ‘valuable’ primary treatment
Retinal transplantation trials for RP look set to begin
EU guidelines give optimal correction licence to fly
Treatment for retinal dystrophies near fruition
Blindness cases climb in 60 to 80 years age bracket
WHO initiative targets childhood blindness
Digitised retinopathy screening improves efficiency
New hypotheses emerge on causes of wet AMD
Cataract surgery on the couch: What the future holds
Dark adaptation offers clue to earlier AMD diagnosis
Smoking may cause blindness in 20% of over 50-year-olds, say studies
New 3-D monitor brings surgery into digital world
CrystaLens new focus for spectacle-free vision
Long-term ICL data promising but cataracts still concern
Tattered Serbian health
system draws on ECOSG in fight against blindness
Atonic pupil a rare
cosmetic problem in cataract patients
Harvard study confirms phaco safety in patients with blebs
Cryoanalgesia affords drug-free anaesthesia for phaco
Paediatric myopia still hangs in ‘nature-nurture’ balance
Orbscan II alternative to infrared pupillometry
Femtosecond laser microkeratome offers advantages of ‘precisely centred’ thin flaps
Anger as surgeons are ‘used as pawns’ in Nidek US legal action
Popular SKBM microkeratomes are
recalled as product line is terminated
Simulating womb greatly reduces ROP rate
Molecular biology insights bring new treatments to fore
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Atonic pupil a rare cosmetic problem in cataract patients

By Cheryl Guttman

FORT LAUDERDALE, FL - Atonic pupil is an uncommon complication in modern small-incision cataract surgery but can be an important cosmetic and symptomatic problem for affected patients, reported researchers at the annual meeting of the Association for Research in Vision and Ophthalmology.
A retrospective review of 1,114 cataract surgery cases performed at the Penn State Milton S. Hershey Medical Centre over between 1992 and 2002 identified the occurrence of atonic pupil in eight eyes (0.7%).

A single surgeon performed all the procedures. The study excluded patients who had undergone combined cataract/glaucoma surgery.
The surgical technique consisted of phacoemulsification with implantation of a posterior capsule IOL in all cases. Among the eight eyes with atonic pupil, five had surgery through a scleral tunnel incision.
However, a clear corneal incision was used in the other three cases and two of those eyes had topical anaesthesia only. Anaesthesia was delivered via a retrobulbar injection in the other six eyes.

All eight patients had normal reactive pupils at the one-day follow-up visit. Fixed pupils unresponsive to light or pilocarpine but reactive to mydriatics were noted at approximately 0.5 to four weeks postoperatively.
Pupil size ranged from 5.5 mm to 8.0 mm. None of the patients had experienced any problems with IOL malposition/dislocation or showed signs of iris atrophy and all were asymptomatic, unaffected by problems with light sensitivity, glare or other disturbing visual problems.

"An earlier study by Percival and colleagues reported a 9% rate of atonic pupil development, although that was a prospective series including eyes operated on with an intracapsular cataract extraction technique and implanted with iris-fixated lenses.
"The much lower rate we observed in our large series is probably an underestimate of more current rates given our retrospective assessment. However, it is consistent with other more recent retrospective studies where prevalence rates have ranged from 0.2% to 1.95%," David L. Galiani MD said.
Interest in undertaking this retrospective study was triggered by the most recent case that involved a 75-year-old patient operated on with topical anaesthesia through a clear cornea incision.

The researchers noted they are not aware of other published cases of atonic pupil development after cataract surgery using a clear cornea technique.
In addition to identifying the rate of atonic pupil development in their cataract surgery population, Dr Galiani and colleagues were interested in determining if they could identify any etiology or common denominator for the complication.
Based on the surgical and medical history findings of their patients, they concurred with previous authors that atonic pupil can arise from any of a variety of factors predisposing to iris sphincter muscle damage or ischaemia.
Possible associations identified in their population included development of elevated IOP postoperatively in three of the eight atonic pupil cases (two eyes with hyphaema and one eye with residual viscoelastic) and the presence of risk factors for atherosclerosis in four others.

The researchers observed that other proposed mechanisms for development of atonic pupil have included intraoperative increased IOP or direct damage to the iris sphincter, toxin exposure, retrobulbar injection-induced damage to the ciliary ganglion and general anaesthesia.
However, they suggested intraoperative increased IOP is unlikely due to the delayed onset of the fixed pupil. Similarly, intraoperative trauma to the iris sphincter is also not plausible since such an event would likely be associated with earlier onset of segmental non-reactivity accompanied by iris atrophy.

Dr Galiani noted that while toxic reactions to the IOL and viscoelastic as well as ciliary ganglion damage secondary to retrobulbar injection cannot be ruled out based on the present series, those factors should be considered only among a variety of possible mechanisms.
This is because atonic pupils have developed after cataract surgery performed without viscoelastic or IOL implantation and using topical or general anaesthesia.

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