Round-up from Orlando

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There were many sessions of use to general optometric practice over the three days of the AAO conference. David Lee (Illinois) showed his research into the colour differences between different editions of the Ishihara colour vision test. He found that the 2005 and the 2006 editions suffered more misalignment of targets from the isochromatic lines than did older editions which would potentially reduce their diagnostic effectiveness. Kristine Huang (California) assessed 500 children (aged seven to 18 years) with amblyopia and found that it was strabismic in 26 per cent, anisometropic in 38 per cent. Of the latter, only one third had had any amblyopia treatment as opposed to two thirds for the strabismic group. This suggests a non-uniform approach to intervention that is worth being aware of.

An interesting study by Russell Woods showed that people vary significantly in their ability to tolerate blur and, by using careful personality rating, he found there was a greater blur tolerance in those lacking in self confidence and of a more disorganised nature. This may have impact on the way we interpret subjective responses in the consulting room, and how we may modify end-point corrections.

Jonathan Jackson (Belfast) has compared 14 different available test charts and found that there are differences in optotypes, optotype height and spacings that may introduce significant differences between practices when monitoring patients. Jackson calls for more standardisation of charts.

A separate study by Jenelle Mallios (New England) showed how two computerised acuity tests gave lower acuity scores than a back-illuminated ETDRS chart. Again, this revealed a lack of consistency well worth highlighting.

An interesting case study from Bernerd Sparks (SECO) described the example of a six-year-old Caucasian male who, some days after a period of hyperthermia, had presented with a sixth-nerve palsy. This resolved within 12 weeks, but Sparks maintained that hyperthermia be considered as a recognised risk factor for sixth-nerve problems.

David Elliott (Bradford) has looked, for some years now, at the role of reduced vision in accidents and falls in the elderly. His latest research was aimed at seeing if prescribing new spectacles increased fall rates in the elderly. By studying the accuracy of various stepping exercises in subjects wearing different corrections, Elliott has been able to show that spectacle magnification is likely to increase fall rates and that 'partial prescribing of large refractive changes in older people at risk of falls is highly recommended'. All elderly patients should be warned of possible visual adaptation demands whenever offered a new correction.

A related but unique study by Jean-Marie Hanssens (Montreal) used a simulation of ophthalmic lens distortion to see how it affected the posture of subjects. Results suggest that postural adaptation among the older subjects to any distortion is more noticeable than among younger patients, suggesting a higher tolerance among the elderly to lens change (presumably not when being fully mobile).

A presentation by Gary Gunderson (Illinois) looked at the macular pigment levels in a range of patients and investigated how this impacts on normal retinal anatomy. He found that pigment levels had no impact on ganglion cell count, but were inversely proportional to retinal thinning. 'Thinning may affect the structure and function of the outer retinal layer,' he stated.

Contact lens matters

There is much to learn about the latest research in contact lenses at the AAO. Of the various papers and presentations to catch my eye, that of Mark Bullimore (Ohio) was notable. He looked at the risk of microbial keratitis among patients undertaking overnight orthokeratology and found no difference to that of other overnight modalities.

Whether to 'rub' as well as 'rinse' has long been a topic of debate in the contact lens world. A new study by Doerte Luensmann (Waterloo) looked at the efficiency of protein removal from silicone hydrogel and conventional hydrogel lenses by soaking only with a multipurpose solution, rubbing and rinsing with an MPS, or using a peroxide-based system. Hydrogen peroxide performed best for lysozyme while no system had any particular benefit for albumin removal. The team note in conclusion that 'overall, cleaning with MPS prior to soaking did not reduce the protein content on the lenses compared to non-rubbed lenses'.

A team led by Michael Wyss (private practice) suggested a new condition, follicular-like conjunctivitis associated with silicone hydrogel contact lens wear. This FoCoSi, as he termed it, 'is a novel and relevant subtype of contact lens induced papillary conjunctivitis'.

Several years ago Optician reported on Nike Maxsight contact lenses and research into whether they had any impact on colour vision and sporting performance. A new study by Amanda Umlandt (Michigan) showed that the Maxsight gives a significant colour shift to its wearer and this may have impact on the sports field or, indeed, driving and daily activities. More research is required, suggested Umlandt.

Historical note

The Academy always offers up some surprises. This year it was good to see a presentation by Wolfgang Vogel on the oculist and barber George Bartisch who is responsible for some of the first detailed notes and illustrations on a wide range of eye diseases such as conjunctivitis, allergic responses and ptosis. It is this work that has earned him the label 'father of ocular medicine'.

All in all, this was a varied and useful conference. ?