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We identified homozygous truncating mutations in HOXA1 in three genetically isolated human populations. The resulting phenotype includes horizontal gaze abnormalities, deafness, facial weakness, hypoventilation, vascular malformations of the internal carotid arteries and cardiac outflow tract, mental retardation and autism spectrum disorder. This is the first report to our knowledge of viable homozygous truncating mutations in any human HOX gene and of a mendelian disorder resulting from mutations in a human HOX gene critical for development of the central nervous system.

Congenital fibrosis of the extraocular muscles type 1 (CFEOM1; OMIM #135700) is an autosomal dominant strabismus disorder associated with defects of the oculomotor nerve. We show that individuals with CFEOM1 harbor heterozygous missense mutations in a kinesin motor protein encoded by KIF21A . We identified six different mutations in 44 of 45 probands. The primary mutational hotspots are in the stalk domain, highlighting an important new role for KIF21A and its stalk in the formation of the oculomotor axis.

Isolated strabismus affects 1–5% of the general population 1 . Most forms of strabismus are multifactorial in origin; although there is probably an inherited component, the genetics of these disorders remain unclear. The congenital fibrosis syndromes (CFS) represent a subset of monogenic isolated strabismic disorders that are characterized by restrictive ophthalmoplegia, and include congenital fibrosis of the extraocular muscles (CFEOM) and Duane syndrome (DURS) 2 . Neuropathologic studies indicate that these disorders may result from the maldevelopment of the oculomotor (nIII), trochlear (nIV) and abducens (nVI) cranial nerve nuclei 3 , 4 , 5 . To date, five CFS loci have been mapped ( FEOM1, FEOM2, FEOM3 , DURS1 and DURS2 ) 6 , 7 , 8 , 9 , 10 , but no genes have been identified. Here, we report three mutations in ARIX (also known as PHOX2A ) in four CFEOM2 pedigrees. ARIX encodes a homeodomain transcription factor protein previously shown to be required for nIII/nIV development in mouse and zebrafish 11 , 12 . Two of the mutations are predicted to disrupt splicing, whereas the third alters an amino acid within the conserved brachyury-like domain 13 , 14 . These findings confirm the hypothesis that CFEOM2 results from the abnormal development of nIII/nIV (ref. 7 ) and emphasize a critical role for ARIX in the development of these midbrain motor nuclei 13 , 14 , 15 , 16 , 17 , 18 , 19 .

To evaluate the effects of topical timolol and apraclonidine on retrobulbar blood flow velocity waveforms in a group of healthy volunteers. Apraclonidine 1% and timolol maleate 0.5% single dose administrations were crossed over double masked in 12 healthy volunteers. The intraocular pressure measurements were followed by Doppler examination of the ophthalmic artery and the central retinal artery. Intraocular pressure was reduced significantly on both treated and fellow eyes after timolol (p = 0.003, p = 0.04 respectively) and after apraclonidine (p = 0.002, p = 0.01 respectively). After apraclonidine administration end diastolic velocity, mean velocity decreased and pulsatility index increased in the ophthalmic artery of both treated and fellow eyes. Resistivity index increased and peak systolic velocity decreased only in the ophthalmic artery of treated eyes. All Doppler indices remained nonsignificant for central retinal artery of both eyes. After timolol administration there were no significant changes of the Doppler indices in the ophthalmic artery and central retinal artery of the treated and fellow eyes. Topical timolol and apraclonidine significantly reduced the intraocular pressure. Single dose administration of apraclonidine 1% increased the vascular impedance distal to the ophthalmic artery. On the other hand, timolol 0.5% had no effect on vascular impedance.

The purpose of this paper is to review different types of superior oblique muscle surgeries, to describe the main areas in clinical practice where superior oblique surgery is required or preferred, and to discuss the preferred types of superior oblique surgery with respect to their clinical outcomes. A consecutive nonrandomized retrospective series of patients who had undergone superior oblique muscle surgery as a single procedure were enrolled in the study. The diagnosis, clinical features, preoperative and postoperative vertical deviations in primary position, type of surgery, complications, and clinical outcomes were reviewed. The primary outcome measures were the type of strabismus and the type of superior oblique muscle surgery. The secondary outcome measure was the results of the surgeries. The review identified 40 (20 male, 20 female) patients with a median age of 6 (2-45) years. Nineteen patients (47.5%) had Brown syndrome, eleven (27.5%) had fourth nerve palsy, and ten (25.0%) had horizontal deviations with A pattern. The most commonly performed surgery was superior oblique tenotomy in 29 (72.5%) patients followed by superior oblique tuck in eleven (27.5%) patients. The amount of vertical deviation in the fourth nerve palsy and Brown syndrome groups (P = 0.01 for both) and the amount of A pattern in the A pattern group were significantly reduced postoperatively (P = 0.02). Surgery for the superior oblique muscle requires experience and appropriate preoperative evaluation in view of its challenging nature. The main indications are Brown syndrome, fourth nerve palsy, and A pattern deviations. Superior oblique surgery may be effective in terms of pattern collapse and correction of vertical deviations in primary position.

A 45-year-old woman who had been operated for blow-out fracture, presented with a complaint of cosmetic concerns about her appearance. Orthoptic evaluation was notable for a left 35 ∆ exotropia and 25 ∆ hypertropia in primary position. Magnetic resonance imaging and the surgical exploration revealed a longitudinally transected left inferior rectus muscle. Transposition procedures which were carried out for left inferior and superior recti provided a good cosmetic result and satisfactory ocular alignment.

ABSTRACTBackground: According to the recently popularized classification of superior oblique (SO) palsy based on congenital variations of the tendon, the primary pathology is the abnormality of the SO tendon rather than an innervational problem in congenital cases. If this hypothesis is true, denervation atrophy of SO muscle should not occur In patients with congenital SO palsy.Methods: Eight patients with traumatic and nine patients with definite congenital SO palsy underwent magnetic resonance imaging (MRI) of the orbit. SO muscle width and cross-sectional area measurements were taken from coronal images and compared with the clinically uninvolved superior oblique muscles.Results: Atrophy of varying degrees was observed in the SO muscle both in congenital and acquired cases. No significant difference was found in the appearance of the SO muscle between acquired and congenital SO palsy groups.Conclusion: We have been unable to demonstrate abnormalities of the SO tendon in both groups. The MRI appearance of the SO muscle suggested that in congenital SO palsy, the pathology is not limited to the tendon; there also is an abnormality of the muscle itself.