Ординатура / Офтальмология / Английские материалы / Manual of Practical Cataract Surgery_Sundararajan_2009
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Understanding the Basics of Strabismus 99
related to accommodation and convergence, though myopia may be undercorrected.
As the spasm of accommodation is the cause for headache, (even for distance ) Hypermetropia has to be fully corrected.
3.Ocular movements in nine cardinal positions should be done. Diplopia chart testing is a useful examination.
4.To find out the angle of deviation
a. Corneal reflex testing (hirschberg test) in infants.
Fig. 5.1
Cover Test
Is to find out "recovery movement" to resume binocular fixation. There are three tests in this:
•Cover test for -Tropias.
•Cover and uncover test -for phorias.
•Alternate cover test - for phorias and tropias.
•Prism bar cover test - to quantitatively measure the total deviation.
•Prisms are placed with the apex pointng towards deviation.
•When prisms are being changed, always make sure that the other eye is covered.
•Base-in or out prism - placed appropriately in front of one eye and then perform alternate cover test, until there is no refixation movement.
100 Manual of Practical Cataract Surgery
6. Measurement of ange of deviation.
•Perimetry method.
•By Synaptophore method and measure the angle of deviation.
•By Maddox rod and maddox wing test.
•With the help of maddox rod at a distance of 6 meters in one eye and look for the streek of light producing crossed diplopia (right side streek crossing to the left side.- Exophoria) or uncrossed diplopia -Esophoria.
The amount of separation can be measured by a prismbar to find out the amount of angle of deviation. The Maddox wing test is for near (33 cm).
7.Measurement of accommodation by RAF ruler.
8.Measurement of convergence by RAF ruler.
9.Diplopia tests.
10.Worths Four-dot tests.
11.State of binocular vision-an assesment to be done.
Understanding the Basics of Strabismus 101
Figs 5.2A to E (For color version see Plate 1)
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Figs 5.3A to C (For color version see Plate 2)
Understanding the Basics of Strabismus 103
Figs 5.4A to C (For color version see Plate 3)
104 Manual of Practical Cataract Surgery
Figs 5.5A to C (For color version see Plate 5)
Understanding the Basics of Strabismus 105
Figs 5.6A to C (For color version see Plate 6)
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Maddox Rod tests one fullpage
•Ask the patient to see a pen torch light.
•Maddox Rod to be placed in one eye, other eye — normal.
→Esophoria
•Correct with base out prism.
→No horizontal phoria.
→Exophoria
•Correct with base in prism.
Figs 5.7A to D
Understanding the Basics of Strabismus 107
TREATMENT OF PHORIAS
a.Refractive errors are to be corrected. Hypermetropia even for distance should be fully corrected to relieve the sustained contraction of ciliary muscles (accommodation), astgmatism and myopia also should be corrected.
b.Orthoptic treatment --This is mainly useful in convergence insufficiency and also in exophorias by doing fusional exercises.to improove fusional reserve.
c.Prismatic spectacles - this is only a temporary arrangement in elderly patients and not a cure in this condition.
d.Improvement of general health. This is an important measure as most of the patients suffer due to serious diseases of physical and mental conditions.
e.Surgery if necessary and in selective cases.
Flow Chart
•The Macular fixation develops in 2 to 3months after birth.
•Convergence and accommodation reflexes develop 2 to 3 months after birth. These reflex center is situated in the occipital cortex areas No. 17 to 19.
We have already dealt with heterophorias
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HETEROTROPIAS
The types of tropias are:
a.Intermittant-here the deviation is not continuously present.
b.Uniocularin one eye only.
c.Alternatingin this the vision in each eye is almost the same. But at a time, only one eye is fixing while the other is deviating and vice versa.
d.Constanthere the deviation is always present.
e.Infantile esotropia.
f.Accommodative esotropia.
g.Non-accommodative and partially accommodative.
Qualitative Types
Esotropia, exotropia, hypertropia, hypotropia etc. The causes of esotropias and exotropias are;-
Convergent Squint-(Concomitant)–Esotropia
1.High hypermetropia producing the over action of accommodation (ciliary muscles) as result of synergic action of accommodation and convergence leads to over action of convergence initially and then for distance.
2.Abnormal physiological incooperation of accommodation and convergence. In case of high hypermetropia in children of 2-3 years,if uncorrected may produce Intermittant squint which becomes constant subsequently.
3.Congenital myopia: The new -born child with congenital myopia does not have a stimulus to see distant object but fixes only the near objectthe mother. Because the medial rectus is more powerful, it remains convergent