Duane retraction syndrome (DRS) is a congenital cranial dysinnervation disorder associated with various ocular and systemic associations.1 Hypermetropia is the most common associated refractive error in these patients.2 Posterior microphthalmos has never been reported in association with DRS. We report a rare case of association of posterior microphthalmos in a case of DRS.
A 7-year-old boy was brought to our institute for general ophthalmic examination and second opinion for high refractive error. There was a history of previous consultation with a local ophthalmologist, who prescribed glasses. The patient’s antenatal, perinatal, and postnatal periods were uneventful. There was no history of consanguinity among the parents or any high refractive error or strabismus in the family members.
On examination, his uncorrected visual acuity was 20/400 in both eyes. His best-corrected visual acuity was 20/60 in the right eye and 20/50 in the left eye, respectively. Ocular motility revealed full and free movements in all gazes in the left eye, but −2 limitation of abduction on a scale of 0 to −4 in the right eye (Fig. 1). There was a narrowing of palpebral fissure height and globe retraction in the right eye on adduction and widening of palpebral fissure on abduction. There was presence of upshoot on adduction. He was orthotropic in primary position for both distance and near (Fig. 1).
Figure 1. Nine-gaze photographs showing typical manifestations of Duane retraction syndrome (type 1) and a near normal-sized eyeball in the right eye.
His anterior segment examination was normal in both eyes. His cycloplegic refraction was +17.5 and +15.5 diopter sphere in the right and left eyes, respectively. His horizontal corneal diameter was normal in both eyes. Biometry and keratometry were done using partial coherence interferometry (IOL Master; Carl Zeiss Meditec, Heidelberg, Germany). Table 1 gives the distribution of the biometry findings of the patient compared with the expected normal values. The effective anterior segment length was 7.32 and 7.2 mm in the right and left eyes, respectively (normal size: 6.0 to 8.1 mm), whereas the posterior segment was short (7.39 and 8.01 mm in the right and left eyes, respectively). In addition, posterior segment examination revealed papillomacular folds in both eyes (Fig. 2A). His optical coherence tomography findings showed presence of a foveal schisis between the inner and outer retinal layers (Fig. 2B).
Table 1: Distribution of the Ocular Biometry Findings of the Patient
Figure 2. (A) Fundus photograph of the right eye showing papillomacular folds. (B) Optical coherence tomography of the right eye revealing schisis between the inner and outer retinal layers.
A final diagnosis of DRS type 1 (Huber’s classification3) in the right eye and posterior microphthalmos, foveal schisis, and ammetropic amblyopia in both eyes was made. Because a foveal schisis was present and best-corrected visual acuity was equal in both eyes, there was no major role of amblyopia therapy. He was prescribed glasses and advised to follow up in 6 months.
DRS is a congenital cranial dysinnervation disorder resulting from paradoxical innervation of the lateral rectus muscle by axons intended for medial rectus muscle caused due to disturbance in the normal embryogenesis between the fourth and tenth week of gestation.1,4 It may be associated with other ocular and systemic congenital anomalies such as sensorineural deafness, upper limb defect, facioauriculo-vertebral anomalies, and cardiac and genitourinary anomalies.1
Posterior microphthalmos is a form of microphthalmos in which the anterior segment is normal in size and configuration but the posterior segment is reduced in size, resulting in axial hyperopia and retinal folds. These patients have horizontal corneal diameter greater than 11 mm and axial length less than 20 mm with no visible malformation.5 It is a relatively rare condition that has been reported to coexist with several other ophthalmic conditions including strabismus (such as non-accommodative esotropia).6–8
In DRS, there is absence or aplasia of sixth nerve nucleus with aberrant innervation of the lateral rectus muscle by a branch of the third nerve. This may be due to failure to differentiate and displace abducens nucleus from the oculomotor nucleus in human embryo.1,4 Most of the cases of posterior microphthalmos are sporadic in onset, whereas it may be autosomal recessive in inheritance with mutation in the membrane frizzled related protein gene in a few cases.9 The encoded protein may play a role in eye development because mutations in this gene have been associated with nanophthalmos, posterior microphthalmos, retinitis pigmentosa, foveoschisis, and optic disc drusen.9
DRS has been reported to be associated with dysplasia of iris stroma, pupillary abnormalities, cataract, heterochromia, persistent hyaloid arteries, choroidal coloboma, distichiasis, and crocodile tears.1
The current report describes a boy with high hypermetropia with eyes that had a small total axial length with normal anterior segment measurements suggesting a diagnosis of bilateral posterior microphthalmos. There were associated papillomacular folds, but ocular motility evaluation revealed limitation of abduction with decrease in palpebral fissure height and globe retraction in adduction in the right eye suggesting DRS type 1 in the right eye associated with posterior microphthalmos.
Garnica-Hayahi et al.10 published a case of unilateral DRS with ipsilateral coloboma and contralateral microphthalmos. However, DRS was associated with bilateral posterior microphthalmos in the current case.
DRS may also be associated with uncorrected refractive errors, but high hyperopia (> 8 D) is unusual. Kirkham2 studied the usual refractive errors in DRS and found 82% of patients had hypermetropic refraction on retinoscopy; 23% among them were high hyperopes with refractive error within 4 to 8 D. None of the cases had high hyperopia (> 8 D). Diagnosis of posterior microphthalmos can be suspected in a patient with high hyperopia but normal-sized eyeballs and can be confirmed by obtaining definite measurements of the anterior and posterior segment of the eyeball.
Conversely, limited literature is available on association of strabismus with posterior microphthalmos. Spitznas et al.,6 Slotnick et al.,7 and Walton8 reported association of posterior microphthalmos with esotropia that remained constant. However, to the best of the authors’ knowledge, there are no previous reports that have found DRS with posterior microphthalmos that may itself have implications of posterior segment complications such as papillomacular choroidal folds, retinal folds, and uveal effusion syndrome.11
We postulate that this could have occurred due to exposure to some unknown common mutagen at the time of the embryogenesis. This might be a newer previously undescribed association of DRS. This case report highlights the association of DRS with posterior microphthalmos and a need for detailed evaluation of patients with DRS with high hyperopia to diagnose this rare condition and a close follow-up for possible complications (elevated papillomacular folds, uveal effusion syndrome, and pigmentary retinopathy) associated with posterior microphthalmos.
- DeRespinis PA, Caputo AR, Wagner RS, et al. Duane’s retraction syndrome. Surv Ophthalmol. 1993;38:257–288. doi:10.1016/0039-6257(93)90077-K [CrossRef]
- Kirkham TH. Anisometropia and amblyopia in Duane’s syndrome. Am J Ophthalmol. 1970;69:774–777.
- Huber A. Electrophysiology of the retraction syndrome. Br J Ophthalmol. 1974;58:293. doi:10.1136/bjo.58.3.293 [CrossRef]
- Saad N, Freeman B, Lee J, et al. The pathogenesis of Duane’s syndrome. Strabismus. 1994;2:137. doi:10.3109/09273979409057140 [CrossRef]
- Meire F, Leys M, Boghaert S, de Laehy JJ. Posterior microphthalmos. Bull Soc Belge Ophtalmol. 1989;231:101–106.
- Spitznas M, Gerke E, Bateman JB, et al. Hereditary posterior microphthalmos with papillomacular fold and high hyperopia. Arch Ophthalmol. 1983;101:413–417. doi:10.1001/archopht.1983.01040010413014 [CrossRef]
- Slotnick S, Fitzgerald DE, Sherman J, et al. Pervasive ocular anomalies in posterior microphthalmos. Optometry. 2007;78:71–77. doi:10.1016/j.optm.2006.08.016 [CrossRef]
- Walton DS. What’s your diagnosis?J Pediatr Ophthalmol Strabismus. 2005;42:331,359.
- Crespi J, Buil JA, Bassaganyas F, et al. A novel mutation confirms MFRP as the gene causing the syndrome of nanophthalmos-retinitis pigmentosa-foveoschisis-optic disc drusen. Am J Ophthalmol. 2008;146:323–328. doi:10.1016/j.ajo.2008.04.029 [CrossRef]
- Garnica-Hayashi RE, Vargas-Ortega J, Zenteno JC, et al. Left-sided Duane’s syndrome and retinal coloboma associated with contralateral microphthalmia. Strabismus. 2007;15:113–117. doi:10.1080/09273970701431418 [CrossRef]
- Khairallah M, Messaoud R, Zaouali S, et al. Posterior segment changes associated with posterior microphthalmos. Ophthalmology. 2002;109:569–574. doi:10.1016/S0161-6420(01)00996-4 [CrossRef]
Distribution of the Ocular Biometry Findings of the Patient
|Variable||Horizontal Corneal Diameter (mm)||Keratometry (D)||Axial Length (mm)||Anterior Chamber Depth (mm)||Lens Thickness (mm)||Anterior Segment Length (mm)||Posterior Segment Length (mm)|
|Right eye||11.5||44.12 @90°; 43.50 @180°||14.71||2.92||4.40||7.32||7.39|
|Left eye||11.5||44.50 @90°; 43.50 @180°||15.21||2.90||4.30||7.20||8.01|
|Normal value||11.3 ± 0.4||43.83 ± 1.21||23.4 ± 0.75||2.9 ± 0.3||4.3 ± 0.3||7.2 ± 0.3||15.3 ± 0.7|