الفهرس 
Patients and methodsOnly 14 pages are availabe for public view
 |  | from | 109 |  |  |
| | | from | 109 | | |
Abstract
SUMMARY
Management of unilateral cataract in children is a difficult
problem in ophthalmology. The major obstacle is not surgical
rather, it is related to the long term problems involving the aphakic
correction and occlusion therapy.
Amblyopiaz-
The critical period in visual development has been one of the
central concepts to emerge during the last few years. The recent
studies proved irreversible anatomical and physiological changes
occuring in lateral geniculate body following visual deprivation
with an onset during the first few months of life. From
observations on the visual outcome ofpaticnts with congenital or
acquired cataract, it was suggested that susceptability to
deprivation amblyopia decreased logarithmically with age, and
thatthis period lasts approximately Six years in humans.
The usual method to treat amblyopia is the occlusion
therapy, and occlusion should be started soon after the proper
optical correction.
Contact lensest-
Contact lenses have certain advantages as it reduce retinal
image disparities to 4-8 % thus it maintain binocular single vision.
It abolishes the prismatic effect caused by aphakic spectacles and
35
the visual field is enlarged. The main advantage is the ability to
meet the changing refractive needs of the child. However contact
lenses have difficulties and disadvantages:- The high loss rate, the
risk of causing trauma, the intolerance. Even in successful contact
lens wearers, there are significant amblyopia producing factors
such as non-wear periods and induced vertical diplopia caused by
decentration of these high-plus, low riding lenses.
A proper contact lens fitting can be done by obtaining a
keratometric reading for the corneal curvature, selection of the
widest lens diameter to minimize loss rate, and the power is
determined after retinoscopy with added over correction for near
focus in young children.
As regards to the type of contact lens soft lenses, extended
wear lenses, hard lenses can be used and each has its advantages
and disadvantages.
Intraocular Lensest-
With the use of I.O.L. implantation, a relatively equal retinal
size image is obtained, and there is no decentration with induced
vertical diplopia experienced with contact lenses. Moreover, there
is no chance for contamination, intolerance, difficulities in
preservation and handling.
36
The selection of the type ofl.O.L depends upon the condition
of anterior segment. Regarding the power of I.O.L, there are
different options.
Whether to use an I.O.L. power that is suitable for an adult
and thus allowing the child to grow towards emmetropia or to
implant an I.O.L that produces an immediate emmetropia but this
will induce errors of increasing magnitude as the eye grows.
Complicationz-
There are peculiar complication releated to the I.O.L
implantation in children, they can be summarised as follows:-
* Operative complications as global collapse, posterior
capsular rupture and vitreous loss, hyphema, IfIS
complications and poor I.O.L placement.
* Post operative complications as striate keratitis, corneal
oedema, iridocyclitis, iris complication pupillary fibrin
membrane, secondary glaucoma, I.O.L dislocation,
endophthalmitis and I.O.L precepitotes.
Epikeratophakia:-
Epikeratophakia involves the onlying of pre-lathed donor
lenticule onto the host cornea which has been denuded of its
epithelium.
It is extraocular, safe and reversible procedure. The operation
IS recommended to be used in infants above one year of age as the
37
highest technical failure rate with the difficulty in predicting the
power requirements are much demonstrated in this age group.
Complications-
Epithelial defects, infection, irregular astigmatism, interface
opacities, prolonged lenticular haze and unpredictability.
Conclusionz-
The acceptable view is to remove the visually significant
unilateral cataract as early as possible and to fit the child with a
contact lens as primary procedure. If contact lens proves
inadequate to prevent amblyopia, I.O.L. implantation or
epikeratophakia may be considered.