Original Article
Type of Horizontal Deviation in Consanguinity
Samia Iqbal,
Hakim Anjum Nadeem
Pak J Ophthalmol 2018, Vol. 34, No. 2
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See end of article for authors affiliations
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.. Correspondence to: Samia Iqbal Department of Ophthalmology, The University of Lahore Email: samiaiqbal988@gmail.com |
Purpose: To find out the association and types of horizontal deviation in
consanguinity. Study Design: Cross-sectional study. Place and duration of Study: Department of Ophthalmology, The University of
Lahore teaching hospital from September to December 2017. Material and Methods: In this study, 93 patients
of 3 to 15 years, with diagnosis of horizontal deviation and positive history
of consanguinity were included in the study. While the patients with vertical
deviation and negative history of consanguinity were excluded from study. Data was collected by
self-designed proforma after taking consent from patients having history of
consanguinity. The visual acuity screening and orthoptic assessment were
performed on the sample of 93 patients using snellen chart for visual acuity
and pen torch for Hirschberg test, cover uncover test and alternate cover
test and prisms for krimsky test. Data was analyzed using SPSS version 20. Results: Out of 93 patients, 55 (59.1)
had exotropia and 38 (40.8%) had esotropia. 17 (18.2%) had emmetropia, 22 (23.65%)
had myopia, 7 (7.5%) had hyperopia, 25 (26.8%) had myopic astigmatism, 10 (10.7%)
had hyperopic astigmatism and the remaining 12 (12.9%) had mixed astigmatism. Conclusion: Consanguinity is related with horizontal deviation and
refractive errors. Exotropia is found to be more common in these cases. Key Word: Consanguinity,
Horizontal deviation, Myopia. |
Misalignment of the eyes is called deviation, squint or
strabismus. It is a state in which the eyes do not
appropriately align with each other while focusing at an object. Deviation can
be constant or intermittent. Horizontal deviation is divided into two main
types; esodeviation (convergent deviation) and exodeviation (divergent deviation)
which can be present in one or both eyes1.
Consanguinity is the
belonging from the same kinship as another person. Characteristically descent
from similar antecedent as another individual is seen especially in cousin
marriages2. The credential of relative consanguinity may be confirmed with a
consanguinity table wherein every level of lineal consanguinity (meiosis)
appears as a row3. Consanguinity causes many disorders
including3 premature ear shot damage, premature visual system
development and perceptive damage, intelligent delay or learning disorder, growing
delay or failure, hereditary blood disease and mental disorder like epilepsy4.
Several recent studies suggested that there is greater frequency of horizontal deviation amongst parental cousin
marriages5. Survey of 7200
patients of strabismus has shown that almost 30% patients had a positive
history of consanguinity6.
The genetics of common styles of horizontal
deviation is not properly diagnosed. The mode of horizontal deviation may be
recessive, dominant or having different factors. Numerous chromosomal
susceptibility loci have been identified.7 It appears that the
dominant and recessive association and co-dominant heirloom type of
transmission was associated with esotropia in early age. The horizontal
deviation seen due to autosomal recessive genetics is mentioned in
consanguinity8.
Regarding these records, it appears that
evidently recessive shape of heirloom shows an essential position within the
case of horizontal deviation. Alteration in selection correspondences can be sought-after
pre revealing of horizontal deviation in children of parental cousin marriages9,10. The purpose of our study was to find out the association and types of
horizontal deviation in consanguinity in our population.
MATERIALS
AND METHODS
It was a cross sectional
study conducted on 93 patients. In this study 93 patients of 3 to 15 years,
with diagnosis of horizontal deviation and positive history of consanguinity
were included. While the patients with vertical deviation and negative history
of consanguinity were excluded from study. Sample size was estimated by
probability convenience method. All patients were diagnosed with horizontal
strabismus by orthoptic assessment. Patients of all other ages or having no
positive history of consanguinity were excluded from the study. The purpose of
the study was to find the type of horizontal strabismus in consanguinity.
Therefore, all patients underwent measurement of distance (6 m) and near (33
cm) visual acuity by using near visual acuity charts and Snellen distance
charts. Orthoptic assessment,
Hirschberg, cover uncover test and alternate cover test were done to rule out
the horizontal deviation. Data was collected by self-designed proforma after
taking consent from patients having history of consanguinity. The results were analyzed by using SPSS version 20.
RESULTS
There
were 93 patients were included in study. Out of these 28 (30.1%) were
males and 65 (56.9%) were females (Table 1). The age distribution is shown in
table 2.
There
were 55 (59.1) patients with exotropia and 38 (40.8%) had esotropia (table 3).
Table 1:
Gender distribution
|
Frequency |
Percent |
Valid Percent |
Cumulative Percent |
|
Valid |
Female |
65 |
56.9 |
56.9 |
56.9 |
Male |
28 |
30.1 |
30.1 |
30.1 |
|
Total |
93 |
100.0 |
100.0 |
100 |
Table 2:
Age distribution.
|
Frequency |
Percent |
Valid Percent |
Cumulative Percent |
|
Valid |
3
6 |
19 |
20.5 |
20.5 |
20.5 |
7
11 |
38 |
40.8 |
40.8 |
79.5 |
|
12 15 |
36 |
38.7 |
38.7 |
100.0 |
|
Total |
93 |
100.0 |
100.0 |
|
Table 3:
Type of deviation.
|
Frequency |
Percent |
Valid Percent |
Cumulative Percent |
|
Valid |
Esotropia |
38 |
40.8 |
40.8 |
40.8 |
Exotropia |
55 |
59.1 |
59.1 |
100 |
|
Total |
93 |
100.0 |
100.0 |
|
Table4: Distribution of patients
according to Refractive Error.
|
|
Frequency |
Percent |
Valid Percent |
Cumulative Percent |
Valid |
Emmetropes |
17 |
18.2 |
18.2 |
18.2 |
Myopia |
22 |
23.65 |
23.65 |
41.8 |
|
Hyperopia |
7 |
7.5 |
7.5 |
49.3 |
|
Myopic
Astigmatism |
25 |
26.8 |
26.8 |
76.1 |
|
Hyperopic
Astigmatism |
10 |
10.7 |
10.7 |
88.8 |
|
Mixed astigmatism |
12 |
12.9 |
12.9 |
100.0 |
|
Total |
93 |
100.0 |
100.0 |
|
There were 17 patients (18.2%)
with emmetropia, 22 had (23.65%) myopia,
7 (7.5%) were hyperopes, 25 (26.8%) showed myopic astigmatism and 10 (10.7%)
had hyperopic astigmatism. The remaining 12 (12.9%) had mixed astigmatic error.
DISSCUSSION
The consanguinity and types of horizontal deviation
is not properly identified. The mode of horizontal deviation inheritance can be
dominant, recessive, or multifactorial11. Oligogenic heirloom for childhood
esotropia was seen in a huge parental cousin marriage population12.
Similar results were obtained from recent study. Autosomal recessive
inheritance in horizontal deviation has been seen in consanguinity and mostly
infantile esotropia seen with hypermetropia13.
In our study we found that myopic astigmatism was
the most common association with horizontal deviation. It is concluded from
another study that due to autosomal recessive linkage, higher myopia was
associated with exotropia in many children. All these children of myopia with
exotropia had positive history of consanguinity14. Infantile
esotropia with hypermetropia and exotropia with myopia cases were observed due
to consanguinity. Anisometropic amblyopia in many school-going children was
examined and 65% had positive history of consanguinity15.
The parental cousin marriage is an extremely rooted community approach
between one fourth of the world populace3. Consanguineous communities are trying to find counseling on
consanguinity16. The number
one health care agencies are faced with consanguineous couple stressful
solutions to their questions on the predicted health dangers to their offspring17. In clinical inheritances, a parental cousin marriage is
defined as a relation between two individuals who are associated as second
cousins or closer, with the coefficient breeding equal or higher than 0.0157, where
the coefficient characterizes extent of the ratio of loci at which the children
of a parental cousin marriages is predictable to inherit identical copies of
genes from both parents18. Similar
studies suggested that inheritance has an important role in the etiology of
strabismus. Previous studies indicated the occurrence rate of 70 to 85% among
monozygotic twins and 35 to 50% among dizygotic twins and all these offspring
have significant myopia with exotropia19. In another similar research, strong genetic element in hyperopic
accommodative esotropia was observed20.
We found esotropia in 40.8% of our cases
while exotropia was seen in 59.1% cases. Schlossmann
and Priestley suggested that 47.8% of patients with horizontal deviation, 49.9%
with esotropia and 36.9% with exotropia, had positive history of parental
cousin marriages21. Other
similar research showed that incidence of horizontal deviation in consanguinity
is 65% higher as compared to normal population22. The limitation of our study is the small sample size with single
center. More studies are required to find a generalizable recommendation.
CONCLUSION
Consanguinity causes abnormality in the
eyes and causes refractive errors. Horizontal deviation is seen in the children
having age 3 to 15 years and positive history of consanguinity. It is concluded
that consanguinity causes deviation in the eyes and exotropia is more common.
Authors Affiliation
Dr. Samia Iqbal (OD)
Doctor of Optometry, PGR MS opto(UOL).
Department of Optometry & Visual
Sciences (DOVS)
The University of Lahore teaching
hospital Lahore.
Dr. Hakim Anjum Nadeem (OD)
Doctor of optometry. PGR MS Opto (UOL).
Senior lecturer, DOVS, UOL Lahore.
Role of Authors
Dr. Samia Iqbal
Study design, review of literature and
data analysis.
Dr. Hakim Anjum Nadeem
Article review and manuscript
preparation.
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