Læknablaðið - 15.06.1997, Side 77

LÆKNABLAÐIÐ 1997; 83
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nite PEX 15.2% also had glaucoma compared
with 1.9% of the remainder of the group, whereas
27.8% ofPOAG eyes had definite PEX. Approx-
imately the same proportion (one third) had PEX
in both eyes, the right eye and in the left eye. On
image analysis PEX was in particular visible on
the lens capsule. EAS 1000 system revealed a
decrease of the A/C depth of 0.013 mm per year
which was in agreement with increase in the lens
diameter. The anterior chamber was statistically
significantly deeper in males than in females ex-
cept for those 80 years and older and the same was
also found to be true regarding the chamber angle
width.
Conclusion: The prevalence of POAG subsum-
ing PEX increases with age and is more common
in males than females whereas PEX is more com-
mon in females than males. The prevalence of
PEX increases with age and may even be under-
estimated in the oldest age group due to pseu-
dophakia. PEX greatly increases the risk of de-
veloping POAG whereas POAG greatly increas-
es the risk of developing visually disabling
cataract. A/C depth and angle width can be accu-
rately documented by this image analysis system
and were found to decrease with age.
A-8. Cognitive visual dysfunction in chil-
dren
Dutton Gordon N, Houliston Mary Jane, Tajuri
Abdel
From The Royal Hospital for Sick Children, Glas-
gow, Scotland
Introduction: Damage to the visual cortex and
visual association areas is common in children
with cerebral palsy and those with treated hydro-
cephalus. The types of cognitive visual problem
encountered in these two groups of children have
not. hitherto, been adequately determined.
Material and niethods: This presentation sum-
marises the results of two separate studies. In the
first study, detailed history taking and ophthalmic
examination was carried out in a dedicated pae-
diatric visual assessment clinic in a consecutive
series of 80 children in whom damage to the cere-
bral cortex was responsible for impaired vision.
In 20 of these children five types of cognitive
visual dysfunction were identified in varying com-
binations and degrees of severity.
The nature of these deficits was classified and
used to develop aquestionnaire which was admin-
istered to the parents of 50 children with treated
hydrocephalus and 200 age matched children for
whom the CT scan findings were reviewed.
Kesults and discussinn: The types of visual def-
icit identified during the initial study comprised:
1. Impaired recognition of faces, and in some
cases, animal form. This was associated with right
occipital damage.
2. Impaired object and shape recognition asso-
ciated in some cases with dyslexia which was pri-
marily associated with left occipital damage.
3. Impaired perception of movement associ-
ated with bilateral damage in the region of the
middle temporal lobe.
4. Impaired simultaneous perception (bigger
ground problems) associated with biparietal dam-
age and quadraparesis.
5. Impaired depth perception (astereocognosis).
The questionnaire survey identified either per-
manent or frequent problems in these five do-
mains occurring in various combination in 53% of
the children with hydrocephalus but in none of
the control subjects.
A-9. Visual impairment in Icelandic chil-
dren
Guðmundur Viggósson
From The Department of Ophthalmology, Uni-
versity of Iceland, Reykjavík, Iceland
Iceland has a population of about 270 thousand
people. The Icelandic Low Vision and Rehabil-
itation Clinic in Reykjavík was established 10
years ago and has compiled data of visually im-
paired children (<17 years) ever since.
Each record contains at least the following in-
formation: sex, year of birth, year of registration,
classification of visual impairment,ocular diag-
nosis, systemic diagnosis, aetiology and eventual
additional impairments. The ocular diagnoses
were compiled into groups, and coding systems
for aetiology and additional impairments were
developed.
The WHO-definition: best corrected visual
acuity in best eye less than 6/18 or visual field less
than 10 degrees around fixation was used for low
vision and visual acuity less than 3/60 or visual field
less than 5 degrees around fixation for blindness.
The prevalence of visual impairment in child-
hood was 1.1 per 100,000 child-population age
0-17 years. The sex distribution revealed a dom-
inance of males compared to the general pop-
ulation at the same age (1.56/1). Cases with non-
genetic aetiology showed, though to a lesser ex-
tent, the same relative preponderance of males.
The diseases in males caused by x-linked genetic
factors do therefore not fully explain the sex dis-
tribution observed in the study.
It is demonstrated that prenatal factors, in-
cluding genetic aetiologies, is involved in a large