Oct 2016

SPECIAL FEATURE: DRY EYE
CONTINUED FROM PAGE 10
Fig 2. Cylindrical collarettes are suggestive of Demodex
infestation
in blepharitis. Unfortunately, there are
major deficits in our ability to diagnose
ocular demodicosis in the clinical
setting, which impacts upon the timely
instigation of appropriate treatment.
Currently clinicians rely on high
magnification microscopic examination
of epilated lashes to confirm Demodex
presence (see Fig 2.), but inaccuracies
in this technique, that complicate
diagnosis, are recognised to exist due to
variations in mite numbers between an
individual’s lashes, and the potential for
obscuration of mites by crusts around
the lash base. In order to overcome these
difficulties, Kim has helped develop a
polymerase chain reaction (PCR)-based
assay that detects and amplifies a
Demodex-specific sequence from the
16s ribosomal RNA gene; the presence
and quantity of which can be visualized
using gel electrophoresis. He is also
working with the team to develop a latex
agglutination assay using chitinase and
wheat germ agglutinin which binds to
chitin, the main constituent of Demodex.
This in-clinic diagnostic test will enable
practitioners to determine whether the
patient has Demodex infestation at a
clinically significant level to indicate need
for treatment and may have benefits in
future epidemiological studies.
Microbial keratitis studies
Sanjay Marasini
Microbial keratitis (MK) describes a
potentially devastating acute corneal
infection that can be caused by a variety
of pathogens including bacteria, virus,
fungi and protozoans, with dry eye
disease being a common predisposing
factor. Despite improving diagnostic
approaches and management options,
however, MK remains a difficult disease
to treat, and disease incidence has been
rising steadily. Sanjay Marasini, a PhD
student within the OSL, has recently
completed a retrospective review of
hospitalized cases of MK (2013-2014)
at Greenlane Clinical Centre (GCC),
Auckland. In his review, he identified
increasing disease due to more virulent
bacterial species, such as Pseudomonas
aeruginosa. Contact lens use was the
most common risk factor leading to MK in
Auckland followed by pre-existing ocular
surface disease of varying aetiology.
Consistent with previous literature,
gram-negative bacteria, most frequently
Pseudomonas aeruginosa, were more
common among contact lens wearers.
Increasingly, inefficacy of commonly used
antibiotics, against such virulent bacteria,
has been predicted as a major threat. In
Maransini’s recently published paper on
this Auckland-based retrospective review,
he noted that, in laboratory testing 67%
of gram-negative bacteria exhibited
resistance to cefuroxime, one of the
most frequently prescribed antibiotics for
bacterial keratitis during the 2013 to 2014
period. (For more on how bacteria affects
dry eye see p14).
Tackling antibiotic resistance
Concerning antibiotic resistance
statistics, such as these, provide
impetus for the pharmaceutical industry
to develop the next generation of
antibiotics, but they also make the quest
for alternative bactericidal therapies
increasingly attractive. In this context,
the OSL – in collaboration with patentholder,
ophthalmologist Dr Simon Dean
– is continuing to explore the potential
of ultraviolet C (UVC) radiation to treat
corneal infection. Marasini’s pre-clinical
research, investigating the minimum
safe dose of UVC that is effective in
halting bacterial growth, has shown
interesting preliminary results. These
are being translated to the next phase
of his study, which will be completed
over the next year and will involve the
use of bioluminescent bacteria. With
the prevalence of visual impairment
secondary to infectious keratitis on
the rise globally, the potential for UVC
to contribute to the safe and effective
management of corneal disease, either
alone or as an adjunct therapy, is an
exciting prospect which, if successful,
could be extended to other branches of
medicine.
Youʻre
leaving me…
arenʻt you?
Tackling dry eye treatment dilemmas
BY JAGRUT LALLU*
Many companies claim their drop is ideal for dry
eye, but the reality of deciding which drop to use,
when, is not simple. There are a myriad of tests
that dry eye specialists employ prior to prescribing.
We are currently developing a comprehensive dry eye tool
that uses what we have available in terms of testing and
treatment to help practitioners simplify the diagnosis and
prescribe effective treatment. Plus, the data collected can
be used by research teams to more effectively develop
algorithms using online infrastructure for practitioners.
Currently, the process for effective patient care employs
a series of questionnaires, as no one questionnaire fulfills
all needs. Examples include: OSDI, McMonnies and SPEED.
Ours includes a patient/practitioner portal and treatment
tool/algorithm and employs all three questionnaires, with
two being repeated prior to each follow-up/review.
A brief summary of the diagnostic tests (not all) that
our tool will include are:
• Phenol red thread test – if less than 10mm dry eye
indicated
• Tear Lab – measures tear film osmolarity. In general,
an increase in osmolarity is a marker for increased
inflammation. If the results indicate a measurement >308
= dry eye present;