Strabismus

Strabismus Publications

Whitman MC, Di Gioia SA, Chan W-M, Gelber A, Pratt BM, Bell JL, Collins TE, Knowles JA, Armoskus C, Pato M, Pato C, Shaaban S, Staffieri S, MacKinnon S, Maconachie GDE, Elder JE, Traboulsi EI, Gottlob I, Mackey DA, Hunter DG, Engle EC, Engle EC. Recurrent Rare Copy Number Variants Increase Risk for Esotropia. Invest Ophthalmol Vis Sci 2020;61(10):22.Abstract
Purpose: To determine whether rare copy number variants (CNVs) increase risk for comitant esotropia. Methods: CNVs were identified in 1614 Caucasian individuals with comitant esotropia and 3922 Caucasian controls from Illumina SNP genotyping using two Hidden Markov model (HMM) algorithms, PennCNV and QuantiSNP, which call CNVs based on logR ratio and B allele frequency. Deletions and duplications greater than 10 kb were included. Common CNVs were excluded. Association testing was performed with 1 million permutations in PLINK. Significant CNVs were confirmed with digital droplet polymerase chain reaction (ddPCR). Whole genome sequencing was performed to determine insertion location and breakpoints. Results: Esotropia patients have similar rates and proportions of CNVs compared with controls but greater total length and average size of both deletions and duplications. Three recurrent rare duplications significantly (P = 1 × 10-6) increase the risk of esotropia: chromosome 2p11.2 (hg19, 2:87428677-87965359), spanning one long noncoding RNA (lncRNA) and two microRNAs (OR 14.16; 95% confidence interval [CI] 5.4-38.1); chromosome 4p15.2 (hg19, 4:25554332-25577184), spanning one lncRNA (OR 11.1; 95% CI 4.6-25.2); chromosome 10q11.22 (hg19, 10:47049547-47703870) spanning seven protein-coding genes, one lncRNA, and four pseudogenes (OR 8.96; 95% CI 5.4-14.9). Overall, 114 cases (7%) and only 28 controls (0.7%) had one of the three rare duplications. No case nor control had more than one of these three duplications. Conclusions: Rare CNVs are a source of genetic variation that contribute to the genetic risk for comitant esotropia, which is likely polygenic. Future research into the functional consequences of these recurrent duplications may shed light on the pathophysiology of esotropia.
Dagi LR, Velez FG, Archer SM, Atalay HT, Campolattaro BN, Holmes JM, Kerr NC, Kushner BJ, MacKinnon SE, Paysse EA, Pihlblad MS, Pineles SL, Strominger MB, Stager DR, Stager D, Capo H. Adult Strabismus Preferred Practice Pattern®. Ophthalmology 2020;127(1):P182-P298.
Elhusseiny AM, Huynh EM, Dagi LR. Evaluation and Management of V pattern Strabismus in Craniosynostosis. J Binocul Vis Ocul Motil 2019;:1-6.Abstract
V pattern strabismus is the most common ocular motor disorder reported in patients with craniosynostosis. Strabismus management may prove challenging, and few studies provide perspective on surgical approach. The purpose of this review is to discuss evaluation and surgical options for treating V pattern strabismus in patients with craniosynostosis. We provide a step-by-step approach to facilitate surgical planning.
Serafino M, Granet DB, Kushner BJ, Dagi LR, Kekunnaya R, Nucci P. Use of the Delphi process for defining successful outcomes for strabismus surgery. J AAPOS 2019;23(6):309-312.Abstract
The purpose of this review was to identify areas of consensus and disagreement among experts for the definition of success following strabismus surgery using the Delphi process. Three rounds of electronic questionnaires were sent to a panel of 28 strabismus experts. Throughout the process, members of the panel were masked to one another's identities to minimize the possibility of influence among members. Prior to data collection, we defined consensus as an 85% agreement on the answer to each question. Questions for which there was no consensus were reworded, and the resultant new questions were used in each subsequent round of questioning. We arrived at consensus for 23 of the 36 questions (64%). Consensus was obtained for recommending unique criteria for the definition of success for certain specific strabismus conditions. In addition, it was considered important that stereopsis and the range of single binocular vision be included in the definition of success for certain types of strabismus.
Heidary G, MacKinnon S, Elliott A, Barry BJ, Engle EC, Hunter DG. Outcomes of strabismus surgery in genetically confirmed congenital fibrosis of the extraocular muscles. J AAPOS 2019;Abstract
PURPOSE: To detail surgical strategy and strabismus outcomes in a genetically defined cohort of patients with congenital fibrosis of the extraocular muscles (CFEOM). METHODS: A total of 13 patients with genetically confirmed CFEOM (via genetic testing for mutations in KIF21A, PHOX2A, and TUBB3) were retrospectively identified after undergoing strabismus surgery at Boston Children's Hospital and surgical outcomes were compared. RESULTS: Age at first surgery ranged from 11 months to 63 years, with an average of 3 strabismus procedures per patient. Ten patients had CFEOM1, of whom 9 had the KIF21A R954W amino acid (AA) substitution and 1 had the M947T AA substitution. Of the 3 with CFEOM3, 2 had the TUBB3 E410K AA substitution, and 1 had a previously unreported E410V AA substitution. CFEOM1 patients all underwent at least 1 procedure to address chin-up posture. Chin-up posture improved from 24° ± 8° before surgery to 10.0° ± 8° postoperatively (P < 0.001). Three CFEOM1 patients developed exotropia after vertical muscle surgery alone; all had the R954W AA substitution. Postoperatively, 1 CFEOM1 patient developed a corneal ulcer. All CFEOM3 patients appeared to have underlying exposure keratopathy, successfully treated with prosthetic replacement of the ocular surface ecosystem (PROSE) lens in 2 patients. CONCLUSIONS: CFEOM is a complex strabismus disorder for which surgical management is difficult. Despite an aggressive surgical approach, multiple procedures may be necessary to achieve a desirable surgical effect. Knowledge of the underlying genetic diagnosis may help to inform surgical management.
Dorr M, Kwon MY, Lesmes LA, Miller A, Kazlas M, Chan K, Hunter DG, Lu Z-L, Bex PJ. Binocular Summation and Suppression of Contrast Sensitivity in Strabismus, Fusion and Amblyopia. Front Hum Neurosci 2019;13:234.Abstract
: Amblyopia and strabismus affect 2%-5% of the population and cause a broad range of visual deficits. The response to treatment is generally assessed using visual acuity, which is an insensitive measure of visual function and may, therefore, underestimate binocular vision gains in these patients. On the other hand, the contrast sensitivity function (CSF) generally takes longer to assess than visual acuity, but it is better correlated with improvement in a range of visual tasks and, notably, with improvements in binocular vision. The present study aims to assess monocular and binocular CSFs in amblyopia and strabismus patients. : Both monocular CSFs and the binocular CSF were assessed for subjects with amblyopia ( = 11), strabismus without amblyopia ( = 20), and normally sighted controls ( = 24) using a tablet-based implementation of the quick CSF, which can assess a full CSF in <3 min. Binocular summation was evaluated against a baseline model of simple probability summation. : The CSF of amblyopic eyes was impaired at mid-to-high spatial frequencies compared to fellow eyes, strabismic eyes without amblyopia, and control eyes. Binocular contrast summation exceeded probability summation in controls, but not in subjects with amblyopia (with or without strabismus) or strabismus without amblyopia who were able to fuse at the test distance. Binocular summation was less than probability summation in strabismic subjects who were unable to fuse. : We conclude that monocular and binocular contrast sensitivity deficits define important characteristics of amblyopia and strabismus that are not captured by visual acuity alone and can be measured efficiently using the quick CSF.
Escuder AG, Hunter DG. The Role of Botulinum Toxin in the Treatment of Strabismus. Semin Ophthalmol 2019;:1-7.Abstract
: To perform a systematic review of the application of botulinum toxin A (BTA) in the management of strabismus in the adult and pediatric populations. : A systematic literature search was performed using the Medline database. : In 1989, with the FDA approval of botulinum toxin (onabotulinum toxin A, or BTA) for the treatment of strabismus, patients were provided with an alternative to surgical recession. In this review, we discuss the uses of BTA in the treatment of acute onset comitant esotropia or smaller angle esotropia and as an adjunct to surgery for larger angle esotropia or sixth nerve palsy. Its uses are also explored in intermittent exotropia and vertical strabismus, including thyroid-associated orbitopathy, fourth nerve palsies, and other orbital pathology. : Despite its transient kinetics, BTA can have permanent effects on ocular alignment, promoting binocularity and reduction of diplopia, and can serve as a primary treatment or a muscle sparing option in patients at risk of anterior segment ischemia or need for future surgeries.
Somsen D, Heidary G. Rapid onset of orbital cellulitis after uncomplicated strabismus surgery. J AAPOS 2019;Abstract
Orbital cellulitis is extremely uncommon following strabismus surgery. When it occurs, the infection has been reported to present from day 1 to within 1 week following surgery and has the potential for significant morbidity postoperatively. We report the case of a 6-year-old boy presenting with unilateral orbital cellulitis growing group A Streptococcus pyogenes on postoperative day 1, after uncomplicated bilateral medial rectus recessions. The patient had two contacts with streptococcal pharyngitis at the time of surgery but was completely asymptomatic himself. We hypothesize that these contacts may have led to the rapid onset of his orbital cellulitis.
Bronstad MP, Peli E, Liu R, Doherty A, Fulton AB. High prevalence of strabismic visual field expansion in pediatric homonymous hemianopia. PLoS One 2018;13(12):e0209213.Abstract
If homonymous hemianopia develops in childhood it is frequently accompanied by strabismus. In some of these cases the strabismus increases the size of the binocular visual field. We determined how prevalent visual-field-expanding strabismus is in children who have homonymous hemianopia. Medical records were examined from 103 hemianopic patients with exotropia (XT) or esotropia (ET). For each participant, we determined whether their strabismus was in a direction that resulted in visual field expansion (i.e. left exotropia with left homonymous hemianopia). Ages at which hemianopia and strabismus were first noted were compared to determine which developed first. The prevalence of XT (24%) and ET (9%) with homonymous hemianopia were both much higher than in the general population (1.5% and 5%, respectively). More strabismic eyes pointed to the blind than seeing side (62 vs 41, 60% vs. 40%, p = 0.02). Exotropic eyes were five times more likely to point to the blind side than esotropic eyes (85% vs 15%). Strabismus, especially exotropia, is much more common in pediatric homonymous hemianopia than in the general population. The strabismus is significantly more often in a visual field-expanding direction. These results support an adaptive role for the strabismus. Patients with HH and exotropia or esotropia should be aware that their visual field could be reduced by strabismus surgery.
Sharma M, MacKinnon S, Zurakowski D, Dagi LR. Consecutive superior oblique palsy after adjustable suture spacer surgery for Brown syndrome: incidence and predicting risk. J AAPOS 2018;Abstract
PURPOSE: To determine the incidence of and to identify characteristics predicting significant superior oblique palsy (SOP) after adjustable superior oblique suture spacer surgery for treatment of Brown syndrome. METHODS: The medical records of patients treated for unilateral Brown syndrome with adjustable suture spacers (2005-2016) were reviewed to identify possible association of age at surgery, spacer length, surgeon performing procedure, severity of Brown syndrome, preoperative hypotropia in primary position and affected side gaze, and reduction in Brown restriction on postoperative superior oblique function. "Good" postoperative superior oblique function was defined as absence of hypertropia and diplopia in primary position and no more than intermittent diplopia in downgaze comfortably fused with ≤4Δ base-down or head tilt of <10°. Presence of postoperative hypertropia in primary position with increase in downgaze met criteria for significant SOP. Postoperative Brown restriction of ≤ -2 indicated resolution of Brown syndrome. RESULTS: Median age at surgery was 59 months, interquartile range (IQR) was 32-82 months, and median spacer length was 6 mm (range, 2-7 mm) for 19 included patients. Preoperative median hypotropia was 9Δ (IQR, 0Δ-12Δ) in primary position and 18Δ (IQR, 5Δ-22Δ) in affected side gaze. Of 19 patients, 16 (84%) achieved sufficient resolution of Brown syndrome, but 6 (32%) developed significant SOP. Modest preoperative hypotropia in affected side gaze was the only predictor of significant SOP (likelihood ratio test = 7.11; P = 0.008). Logistic regression modeling enabled estimation of risk of significant SOP based on preoperative side gaze hypotropia. CONCLUSIONS: Suture spacer surgery can result in significant SOP. Risk may be predicted by magnitude of preoperative side gaze hypotropia.
Cestari DM, Freire MV, Chun BY. Vertical rectus muscle recession versus combined vertical and horizontal rectus muscle recession in patients with thyroid eye disease and hypotropia. J AAPOS 2018;Abstract
PURPOSE: To compare the postoperative vertical drift in patients with thyroid eye disease (TED) with hypotropia who underwent vertical rectus recession alone versus recession combined with horizontal rectus recession. METHODS: The medical records of patients with TED who underwent strabismus surgery for hypotropia between 2006 and 2015 were reviewed retrospectively. Patients were divided into two groups: group 1 underwent vertical rectus recession only; group 2 underwent vertical rectus recession plus horizontal rectus recession. Data collection included pre- and postoperative deviation measurements and amount of surgical recession performed. The amount of postoperative vertical drift between groups was compared. RESULTS: Of 67 patients who underwent surgery during the study period, 18 met inclusion criteria, 9 in each group. Mean postoperative hypotropia was 24.2 in group 1 and 24.5 in group 2 (P = 0.82). Mean vertical deviations were 0.3 and -2.2 (P = 0.134) on postoperative day 1 -0.9 and -8.0 (P = 0.043) at final follow-up for groups 1 and 2. Mean postoperative vertical drift toward hypertropia was 1.2 in group 1 and 6.8 in group 2 (P = 0.048). The surgical success rate for group 1 was superior to that for group 2 (89% vs 67% [P = 0.024]). CONCLUSIONS: There was a significantly larger postoperative vertical drift in TED patients with hypotropia who had combined vertical rectus and horizontal rectus recessions compared with those who underwent vertical rectus recession alone.
Guhan S, Peng S-L, Janbatian H, Saadeh S, Greenstein S, Al Bahrani F, Fadlallah A, Yeh T-C, Melki SA. Surgical adhesives in ophthalmology: history and current trends. Br J Ophthalmol 2018;Abstract
Tissue adhesives are gaining popularity in ophthalmology, as they could potentially reduce the complications associated with current surgical methods. An ideal tissue adhesive should have superior tensile strength, be non-toxic and anti-inflammatory, improve efficiency and be cost-effective. Both synthetic and biological glues are available. The primary synthetic glues include cyanoacrylate and the recently introduced polyethylene glycol (PEG) derivatives, while most biological glues are composed of fibrin. Cyanoacrylate has a high tensile strength, but rapidly polymerises upon contact with any fluid and has been associated with histotoxicity. Fibrin induces less toxic and inflammatory reactions, and its polymerisation time can be controlled. Tensile strength studies have shown that fibrin is not as strong as cyanoacrylate. While more research is needed, PEG variants currently appear to have the most promise. These glues are non-toxic, strong and time-effective. Through MEDLINE and internet searches, this paper presents a systematic review of the current applications of surgical adhesives to corneal, glaucoma, retinal, cataract and strabismus surgeries. Our review suggests that surgical adhesives have promise to reduce problems in current ophthalmic surgical procedures.

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