|Year : 2020 | Volume
| Issue : 10 | Page : 2196-2198
Ocular structural changes in patients with Duane retraction syndrome: Does a correlation exist?
Ramesh Kekunnaya1, Bhagya L Marella2, Hari K Peguda3, Virender Sachdeva4
1 Child Sight Institute, Jasti V Ramanamma Children's Eye Care Center, L. V. Prasad Eye Institute, Kallam Anji Reddy Campus, Hyderabad, Telangana, India
2 Child Sight Institute, Jasti V Ramanamma Children's Eye Care Center, And Brien Holden Institute Optometry and Vision Sciences, L V Prasad Eye Institute, KAR Campus, Hyderabad, Telangana, India
3 Smt. Kanuri Santhamma Centre for Vitreoretinal Diseases, L V Prasad Eye Institute, KAR Campus, Hyderabad, Telangana, India
4 Child Sight Institute, Nimmagada Prasad Children's Eye Care Centre, L V Prasad Eye Institute, GMRV Campus, Visakhapatnam, Andhra Pradesh, India
|Date of Submission||19-Jan-2020|
|Date of Acceptance||03-Apr-2020|
|Date of Web Publication||23-Sep-2020|
Dr. Ramesh Kekunnaya
Child Sight Institute, Jasti V Ramanamma Childrenfs Eye Care Center, Kallam Anji Reddy Campus, L. V. Prasad Eye Institute, Hyderabad, Telangana - 500 034
Source of Support: None, Conflict of Interest: None
Purpose: The purpose of this study was to investigate the structural changes (axial length, central macular thickness (CMT), subfoveal choroidal thickness, and keratometry) in subjects with unilateral Duane retraction syndrome (DRS) as compared with the normal fellow eye. Methods: In this prospective study, we included 34 subjects with unilateral DRS from January 2016 to December 2016 seen at our institute. Data was collected for axial length, keratometry using partial coherence interferometry, CMT, subfoveal choroidal thickness using the enhanced depth imaging-optical coherence tomography (EDI-OCT). All these measurements were compared between the affected and fellow eye. Results: During this period, we included 34 subjects with unilateral DRS (22 Type I, 1 Type II, and 11 Type III). The mean age (±SD) of subjects was 14 ± 8 years (range: 5–28 years). There were 15 males and 19 females. Eyes with DRS were significantly shorter (median axial length 22.4 mm, interquartile range (IQR): 21.56 - 23.17) as compared to fellow eye (median axial length 22.7 mm, IQR: 22.35-23.55), P = 0.04. Choroidal thickness, CMT, and average keratometry were similar in DRS and fellow eyes (P = 0.39, 0.06, and 0.11, respectively). A significant difference in axial length was found only between Type I and Type III DRS (P = 0.03). Conclusion: This study suggests that in subjects with DRS, the affected eye has shorter median axial length when compared with the fellow eye. Prevalence of refractive error in eye with DRS was higher compared to fellow eye. But, there was no difference in magnitude of refractive error found between eye with DRS and normal fellow eye.
Keywords: Axial length, central foveal thickness, Duane retraction syndrome, keratometry, refractive error
|How to cite this article:|
Kekunnaya R, Marella BL, Peguda HK, Sachdeva V. Ocular structural changes in patients with Duane retraction syndrome: Does a correlation exist?. Indian J Ophthalmol 2020;68:2196-8
|How to cite this URL:|
Kekunnaya R, Marella BL, Peguda HK, Sachdeva V. Ocular structural changes in patients with Duane retraction syndrome: Does a correlation exist?. Indian J Ophthalmol [serial online] 2020 [cited 2020 Oct 31];68:2196-8. Available from: https://www.ijo.in/text.asp?2020/68/10/2196/295663
Duane retraction syndrome (DRS) is a congenital cranial dysinnervation disorder (C2D2), which results from the absence of normal innervation and a misinnervation of the lateral rectus muscle by the oculomotor nerve.,, Based on the electrophysiological studies, Huber classified DRS into three types. Type I DRS is characterized by limitation of abduction, Type II DRS presents with limitation of adduction and Type II DRS has a limitation of both adduction and abduction. All types of DRS are characterized by a reduction in the palpebral fissure height on attempted adduction which results from co-contraction of the lateral and medial rectus on attempted adduction. Prior studies have shown that eye affected with DRS has a higher tendency for hypermetropia., The reasons for this hypermetropic refractive error is still questionable. One plausible hypothesis might be that hypermetropia might be secondary to mechanical stress secondary to globe retraction, however, it needs to be investigated.
We carried out this study to investigate the structural changes in subjects with unilateral DRS as compared with the normal fellow eye and to investigate if any correlation existed between structural changes and refractive error in subjects with DRS.
| Methods|| |
This was a prospective study conducted at L V Prasad Eye Institute, Hyderabad during the period Jan 2016–Dec 2016. Prior institutional review board approval was taken from the IRB of our institute and the study adhered to the tenets of the Declaration of Helsinki. Informed consent was obtained from all the subjects before enrolling in the study. We included subjects older than 5 years of age with unilateral DRS Type I, II, or III. We excluded younger children (who are unlikely to cooperate for these measurements, subjects with high myopia (>-6.0 D), which influences retinal and choroidal thickness measurements), uncooperative subjects and subjects whose parents refused to give informed consent.
We enrolled consecutive subjects with unilateral DRS meeting the inclusion and exclusion criteria in our study. All subjects underwent comprehensive eye examination along with detailed squint evaluation and cycloplegic retinoscopy. Spectral -domain OCT (SD-OCT) (Cirrus OCT, Carl Zeiss Meditec, Dublin Germany) was performed and enhanced depth imaging-optical coherence tomography (EDI-OCT) was used to measure the choroidal and central macular thickness (CMT) by two masked examiners three times randomly (2 examiners took these readings on the same day at the same time). Axial length (AL) and keratometry (K) readings were performed using optical biometry (LENSTAR LS 900, Haag-Streit, Ohio USA).
Statistical analysis was performed using IBM SPSS statistics for windows, version 20. Normality of the data was tested using the Kolmogorov–Smirnov test (KS test). AL, keratometry, choroidal thickness, and CMT were compared between the eye with DRS and fellow eye by using Mann–Whitney U test. As there was only one subject with Type II DRS, it was excluded from subgroup analysis and Mann–Whitney test was used to compare the differences in structural parameters between Type I and Type III DRS. Kruskal–Wallis test is used to compare the difference between DRS Type I, Type III, and Normal eyes. Interobserver and intraobserver repeatability for subfoveal choroidal thickness and macular thickness were compared using concordance cross-correlation.
| Results|| |
During the study period, 34 subjects were included in the study, of which 22 subjects had DRS Type I, 11 were Type III, and 1 subject had Type II. The mean age (±SD) of subjects was 14 ± 8 years (5–28 years). There were 15 males and 19 females.
As seen in [Table 1], eyes with DRS were significantly shorter (median axial length 22.4 mm, interquartile range (IQR): 21.56 - 23.17) as compared to fellow eye (median axial length 22.7 mm, IQR: 22.35-23.55), P =0.04. This explains a greater prevalence of hypermetropic refractive error in the eye with DRS (median: 0.25 D, IQR: -0.75 D to + 0.68 D) as compared to the normal eye, (median: Plano, IQR: - 0.68 to Plano). Distribution of refractive error among DRS eyes vs. normal eyes is provided in [Table 2]. The percentage of eyes with hyperopic refractive error was higher in the group with DRS (26.47%) compared to normals (14.70%). The total prevalence of refractive error is higher in the group with DRS Type III (75%) opposed to Type 1 (50%) [Figure 1] was the amount of the refractive error did not show a statistically significant difference between eyes with Type I, Type III, control and combined (Type I and Type III together) DRS (P > 0.05). CMT, subfoveal choroidal thickness, and mean keratometry were similar in DRS and fellow eyes (P = 0.06, 0.39, and 0.11, respectively).
|Table 1: The distribution of the ocular findings in our subjects in the eye with Duane retraction syndrome as compared to the normal fellow eye|
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|Table 2: The distribution of amount of the refractive error and the percentage of refractive error distribution in eyes with Duane retraction syndrome and normal eyes|
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|Figure 1: Distribution of the refractive error in all the groups of DRS and normals|
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Subgroup analysis to compare structural parameters of the effected eye between Type I and Type III DRS showed a significant difference in axial length measurement between Type I and Type III DRS (P = 0.03) [Table 3]. There were no other differences in any of the parameters that were measured. Concordance cross-analysis showed good intra-observer repeatability (0.98 and 0.97 for macular thickness and choroidal thickness measurements, respectively) and interobserver variability (0.92 and 0.97 for macular thickness and choroidal thickness measurements, respectively).
|Table 3: Shows the ocular changes of the eye with DRS in Type I and Type III DRS. Median with interquartile range (IQR) is provided|
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| Discussion|| |
Although it is well known that DRS is a congenital cranial dysinnervation disorder (C2D2) and clinical characteristics of the disease are well reported, there is limited literature characterizing the structural differences in the eyes with DRS.
Similar to the previous studies, this study suggests that eyes with DRS are more likely to be hypermetropic., The median refractive error in the DRS eyes was slight hypermetropic as compared to normal eyes. Kirkham et al. reported in their series of 110 subjects, 90 (82%) subjects had a hypermetropia of > +1.5 D. In addition, 26 (23.6%) subjects had a refractive error ranging from + 4 to + 8 D sphere.
In a previous publication from our institute, 139 (31.5%) cases had hypermetropia or hyperopic astigmatism, while 98 (22.2%) cases had myopia or myopic astigmatism, and 11 (2.5%) cases had a myopic refractive error in one eye and hypermetropia in the other eye. Thus, hypermetropia was observed in about 34% of the eyes of DRS in that series. In this study, the difference in the median refractive error did not reach statistical significance possibly due to sample size.
Further looking into the possible pathophysiology of the hypermetropia, this study suggests that eyes with DRS had shorter axial length compared to the contralateral normal eye. However, there was no statistically significant difference in the average keratometry. This suggests that the tendency of DRS eyes towards hypermetropia was secondary to the short axial length of these eyes. While this is expected but this has not been correlated before, and the authors hypothesize that this might result from the chronic structural changes in the eyeball secondary to the co-contraction of both lateral and medial rectus.
We also looked at the other structural changes such as in the CMT, and subfoveal choroidal thickness. Again, there is no prior literature comparing the CMT and subfoveal choroidal thickness in normal with DRS eyes. However, if we compare with the literature for CMT and subfoveal choroidal thickness among adults and children, it is observed that axial length and therefore refractive error tend to influence the subfoveal choroidal thickness. Chhablani et al. reported that axial length had a negative correlation with the subfoveal choroidal thickness being more in hyperopic children. Yau et al. studied CMT using swept-source OCT in 168 Chinese children aged 4–18 years. They also reported that the myopes had significantly thicker CMT (283.3 ± 57.3 μm, n = 56), than hyperopes (266.2 ± 55.31 μm, n = 60) and emmetropes (259.8 ± 28.7 μm, n = 52), P < 0.0001. They did not report any significant difference in CMT between hypermetropes and emmetropes.
Similarly, Jin et al., reported in a study on Chinese children that while subfoveal choroidal thickness was affected by the axial length with higher thickness in hyperopes, CMT was not significantly influenced by the axial length.
Given these perspectives from the existing literature, we expected a significant difference in the CMT but surprisingly there was no difference in the subfoveal choroidal thickness. This might be due to small sample size or due to ethnic variations. However, larger studies are needed to explore these observations.
Limitations of this study are small sample size, which precludes adequate representation of different subtypes of DRS. Despite these limitations, this study adds to the existing literature with new information on the structural parameters in subjects with DRS, and different subtypes of DRS. Further larger studies are needed to evaluate the differences in various structural parameters of eyes affected with DRS with normal eyes and different subtypes of DRS. Another aspect that might provide insight into these differences might be an analysis of the peripheral thickness of the retina at the muscle insertion with handheld imaging technology that may be helpful to understand the structural changes during the co-contraction.
| Conclusion|| |
This study showed a significant difference in axial length between Type I and Type III DRS. The possible explanation for this could be the eyes with Type III DRS are expected to have more tightness than type I DRS, which might lead to more structural changes in subjects with Type III DRS. This study did not show any other significant difference in refractive error. However, larger studies are needed to explore further these observations.
The work was supported by the Hyderabad Eye Research Foundation (HERF). However, there are no competing interests for any of the authors. We acknowledge all our subjects for active participation in the study.
Financial support and sponsorship
Conflicts of interest
There are no conflicts of interest.
| References|| |
Duane A. Congenital deficiency of abduction, associated with impairment of adduction, retraction movements, contraction of the palpebral fissure and oblique movements of the eye. 1905. Arch Ophthalmol 1996;114:1255-6; discussion 1257.
Yuksel D, Orban de Xivry JJ, Lefevre P. Review of the major findings about Duane retraction syndrome (DRS) leading to an updated form of classification. Vision Res 2010;50:2334-47.
Yang S, MacKinnon S, Dagi LR, Hunter DG. Superior rectus transposition vs medial rectus recession for treatment of esotropic Duane syndrome. JAMA Ophthalmol 2014;132:669-75.
Huber A. Electrophysiology of the retraction syndromes. Br J Ophthalmol 1974;58:293-300.
Gurwood AS, Terrigno CA. Duane's retraction syndrome: Literature review. Optometry 2000;71:722-6.
Kirkham TH. Anisometropia and amblyopia in Duane's syndrome. Am J Ophthalmol 1970;69:774-7.
Tredici TD, von Noorden GK. Are anisometropia and amblyopia common in Duane's syndrome? J Pediatr Ophthalmol Strabismus 1985;22:23-5.
Kekunnaya R, Gupta A, Sachdeva V, Krishnaiah S, Venkateshwar Rao B, Vashist U, et al
. Duane retraction syndrome: Series of 441 cases. J Pediatr Ophthalmol Strabismus 2012;49:164-9.
Chhablani JK, Deshpande R, Sachdeva V, Vidya S, Rao PS, Panigati A, et al
. Choroidal thickness profile in healthy Indian children. Indian J Ophthalmol 2015;63:474-7.
] [Full text]
Yau GS, Lee JW, Woo TT, Wong RL, Wong IY. Central macular thickness in children with myopia, emmetropia, and hyperopia: An optical coherence tomography study. Biomed Res Int 2015;2015:847694.
Jin P, Zou H, Zhu J, Xu X, Jin J, Chang TC, et al
. Choroidal and retinal thickness in children with different refractive status measured by swept-source optical coherence tomography. Am J Ophthalmol 2016;168:164-76.
[Table 1], [Table 2], [Table 3]