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When performed prior to visual maturity, strabismus surgery can result in the development or recovery of binocularity. When strabismus surgery is performed after visual maturity, the functional benefits of the surgery should be dichotomized according to whether the onset of the strabismus was before or after visual maturity. If the onset was after visual maturity, patients typically are diplopic. Specific success rates for eliminating diplopia vary according to the nature of the strabismus; however, overall the success rate is quite high. There is a common misperception that surgery in adults for strabismus that began prior to visual maturity is merely cosmetic. Numerous studies contradict this misconception. Even if the strabismus has been longstanding, most adults will experience some improvement in binocular function after strabismus surgery. In esotropic patients, this improvement typically takes the form of an expansion of binocular visual fields; however, some patients may also regain stereopsis. There are many psychosocial benefits to adult strabismus surgery. This is reflected in the finding that the majority of adults surveyed with strabismus would trade a portion of their life expectancy to be rid of their strabismus.

Summary 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.

Background The Delphi process has been widely used to delineate guidelines for the treatment of disorders for which there is little or no evidence in the published literature. The purpose of this study was to use the Delphi process to identify areas of consensus and disagreement on the definition of success after surgery for each type of strabismus. Methods Two rounds of electronic questionnaires were sent to 28 members of the Strabismus Success Definition Delphi Study Group. For the first round, responses to 70 questions were captured as agree (= 1) and disagree (= 2). For round 2, a total of 89 questions were captured on a Likert scale ranging from 1 (strongly disagree) to 7 (strongly agree). Consensus was determined a priori at 85%. Results In both the first and second rounds, inter-rater agreement of 85% consensus was reached for only 20% of questions. Intra-rater agreement per question was low, with κ values ranging from −0.11 to 0.62. Intra-rater agreement was also low among themes, ranging from poor to fair agreement: κ = 0.25 for motor, κ = 0.28 for sensory, and κ = 0.35 for follow-up. Conclusions This study highlights consensus areas that could be considered by researchers in designing studies and identifies areas where lack of consensus indicates that further research is needed.

To outline a systematic approach to strabismus reoperations. Many strabismologists have a formulaic approach to strabismus reoperations, e.g., treat it as a fresh case, advance previously recessed muscles to the original insertion, etc. Patients and methods: This paper is a collection of pearls gained from the author's 40+ years in practice.Effective strategies for strabismus reoperations are not formulaic and should be tailored to the specific history and findings of the patient. The first, and most important decision, is whether to operate on previously operated muscles or fresh muscles. This should be influenced, in part, by whether one is treating an overcorrection or undercorrection. Limitations of rotations and incomitance patterns should be addressed. Many important decisions should be made intraoperatively based on where muscles are found, their integrity (slipped in the capsule, stretched scar, etc.), repeated intraoperative forced ductions, and spring back balance testing.A proper plan for a strabismus reoperation takes into account a number of preoperative factors, and the surgeon should be prepared to modify the plan based on intraoperative findings.

PURPOSE: To compare long-term outcomes after bilateral lateral rectus recession (BLRc) or unilateral recess-resect (R&R) for primary treatment of childhood intermittent exotropia (IXT). DESIGN: Multicenter randomized clinical trial PARTICIPANTS: 197 children, age 3 to

Purpose Amblyopia is associated with a broad array of perceptual and neural abnormalities in the visual system, particularly in untreated or unsuccessfully treated populations. Traditionally, it has been believed that the neural abnormalities are confined to the visual cortex and subcortex (e.g., lateral geniculate nucleus). Here, we investigate the presence of neuroanatomical abnormalities earlier in the visual stream, in the optic nerves and tracts, of participants with two predominant forms of amblyopia. Methods We used diffusion magnetic resonance imaging and probabilistic tractography to compare the microstructural properties of five white matter visual pathways between 15 participants with amblyopia (eight anisometropic, five strabismic, and two exhibiting both etiologies), and 13 age-matched controls. Results Participants with amblyopia exhibited significantly smaller mean fractional anisotropy in the optic nerve and optic tract (0.26 and 0.31 vs. 0.31 and 0.36 in controls, respectively). We also found greater mean diffusivity in the optic radiation compared to controls (0.72 μm2/s vs. 0.68 μm2/s, respectively). Comparing etiologies, the abnormalities in the precortical pathways tended to be more severe in participants with anisometropic compared to strabismic amblyopia, and anisometropic participants' optic nerves, optic tracts, and optic radiations significantly differed from control participants' (all, P < 0.05). Conclusions The results indicate that amblyopia may be associated with microstructural abnormalities in neural networks as early as the retina, and these abnormalities may differ between amblyopic etiologies.

Purpose To describe the usefulness of anterior nasal transposition of the inferior oblique muscle in the fixing eye to treat nystagmus-mediated head tilt recurring after prior torsional surgery. Methods The medical records of patients who underwent anterior nasal transposition of the inferior oblique muscle in the fixing eye to treat recurrence of head tilt after prior successful torsional surgery were retrospectively reviewed. Results Three patients met inclusion criteria. In all 3 patients head tilt was eliminated after inferior oblique anterior nasal transposition with 2, 5, and 9.5 years’ follow-up. In no case did surgery result in any further intorsion of the eye. We postulate that the surgery was successful by stabilizing the normal compensatory and anticompensatory torsional movements that occur with head tilt. Conclusions Anterior nasal transposition of the inferior oblique muscle effectively treats a recurrent nystagmus-mediated head tilt after prior successful torsional surgery. It does not, however, intort the eye further in this clinical setting and must work via a different mechanism.

BACKGROUND AND PURPOSE When patients with intermittent exotropia show an increase in their near deviation after prolonged monocular occlusion, they have been said to have tenacious proximal fusion (TPF). That term is not adequately descriptive, since this finding can occur without the patient having been allowed to fuse. The purpose of this study is to investigate the possibility that this phenomenon is mediated by the preponderance of binasal retinal disparity and uncrossed localization that occurs with near fixation. PATIENTS AND METHODS Ten patients with intermittent exotropia who manifested TPF were measured at 6 m, 1/3 m, again at 1/3 m after 1 hour of monocular occlusion, and at 1/3 m with a peripheral crossed localization stimulating device (PCLSD) that simulated the retinal bitemporal disparity and peripheral crossed localization usually found with distance fixation. RESULTS For the ten patients, the mean measurement at distance was 28.3Δ±3.1, initially at near was 4Δ±3.9, at near after prolonged monocular occlusion was 25.3Δ±5.3, and at near with the PCLSD was 18.5Δ±4.1. The differences between the initial near measurement and the measurement with the PCLSD, and between the PCLSD and post-prolonged monocular occlusion were significant with P

I welcome you to the new Journal of Binocular Vision and Ocular Motility (BVOM). I am really excited about being the co-editor of this publication with Kyle Arnoldi, CO as my co-editor. Before I ac...

Objective To investigate the relationship between objective and subjective torsion in patients with cyclovertical strabismus and determine whether objective torsion differs according to which eye is fixing. Design A prospective evaluation of tests of objective and subjective torsion. Participants Thirty-six patients with various types of cyclovertical strabismus. Methods Subjective torsion was assessed with the double Maddox rod, and objective torsion was graded in a masked manner from fundus photographs. Main Outcome Measures Quantification of objective or subjective torsion. Results Objective torsion was the same regardless of which eye was used for fixation. However, after prolonged occlusion of the nonaffected eye, there was often an increase in objective torsion in the nonaffected eye. Subjective torsion typically was absent in patients with objective torsion if they did not have bifoveal fusion but was similar to objective torsion in patients with bifoveal fusional potential. Conclusions Assessment of objective and subjective torsion are each important but play separate roles in the evaluation of cyclovertical strabismus. There is no immediate torsional motor shift when fixation switches from the nonaffected to the affected eye. However, prolonged fixation of the affected eye may possibly result in a motor torsional change in the nonaffected eye in some patients. Financial Disclosure(s) The author(s) have no proprietary or commercial interest in any materials discussed in this article.

Purpose To report results of extraocular muscle surgery for superior oblique myokymia when medical treatment fails. Methods A retrospective review of 14 consecutive patients undergoing superior oblique tenectomy and inferior oblique myectomy between 1976 and 2008. Results The mean age of onset of symptoms was 35.4 ± 12.6 years (range, 16-59.5), with a mean duration of oscillopsia of 5 ± 4 years (range, 1.5-17) prior to surgery. Medical treatment was unsuccessful in all 14. Preoperatively, 2 had a small hypertropia that was consistent with an ipsilateral fourth (trochlear) nerve palsy; 12 had no manifest tropia. Postoperatively, all had complete elimination of oscillopsia, and 12 of 14 were free of diplopia in the primary position at 6 meters and 1/3 meter. The only 2 with diplopia in the primary position after surgery were the 2 with a manifest hypertropia preoperatively. Of the remaining 12 patients, 5 had a hypertropia of the affected eye limited to downgaze after surgery (mean of 6.2Δ ± 1.6Δ). Of the 5, 3 needed contralateral inferior rectus surgery, and 1 required prism for downgaze. The mean follow-up was 4.1 ± 2.4 years (range, 0.5-10). At the final visit, none had oscillopsia or uncontrolled diplopia, but 3 (21%) needed prisms. Conclusions Superior oblique tenectomy and inferior oblique myectomy effectively eliminate oscillopsia associated with superior oblique myokymia but result in diplopia in downgaze in approximately 36% of patients, which may cause symptoms in patients who require a bifocal for near work.

Background Antipodean strabismus is a rare clinical entity in which a patient manifests an esotropia when fixating with one eye and an exotropia when fixating with the other eye. It has been described in the settings of marked uncorrected anisometropia, dissociated strabismus or combinations of paresis, and mechanical restriction of eye movement. Methods A retrospective review of four patients with antipodean strabismus. Results All patients demonstrated a unique and uncommon pattern in which there was esotropia with one eye fixating and exotropia with the other eye fixating. None of the patients demonstrated anisometropia or signs of dissociated horizontal deviation. One patient developed antipodean strabismus after prior surgery to correct a traumatic sixth nerve palsy. Another patient had an associated pseudotumor cerebri. The other two patients had no pertinent medical history and, on clinical examination, demonstrated markedly asymmetric accommodative convergence/accommodation (AC/A) ratios. Conclusions Antipodean strabismus is an atypical heterotropia, which can be associated with a variety of clinical findings. This article demonstrates the uniqueness of this clinical entity and illustrates the first association of this pattern with a markedly asymmetric AC/A ratio.

Background: Muscle slippage is an adverse outcome of strabismus surgery. Its incidence is increased if adjustable sutures are used or if surgery is performed on the inferior or medial rectus muscles. Although there are no firm numbers for this complication, studies have suggested incidence rates between 7% and 41% when adjustable suture surgery is performed on the inferior rectus muscle. In theory, the semiadjustable suture procedure should decrease this adverse outcome. This procedure involves suturing the corners of the muscle firmly to the sclera and placing the center of the muscle on an adjustable suture. This study evaluates semiadjustable suture surgery with respect to muscle slippage. Methods: The primary treatment group consisted of 57 patients who underwent semiadjustable suture surgery on a total of 61 muscles that either had never previously undergone surgery or had undergone surgery and had not previously slipped postoperatively. Fifty-five were inferior rectus muscles and 6 were medial rectus muscles. An additional 7 patients had semiadjustable suture surgery on muscles that had slipped after prior surgery and were analyzed separately. The outcome evaluation was at least 6 months after surgery. Results: None of the 57 patients in the primary treatment group demonstrated muscle slippage after semiadjustable suture surgery. One of the 7 patients who had history of prior muscle slippage also had slippage after semiadjustable suture surgery. Conclusion: The semiadjustable suture procedure appears to decrease the incidence of muscle slippage.

Background Traditional teaching holds that there is a partial compensatory countertorsion after head tilt because the intorters in the eye on the side of the head tilt and the extorters in the contralateral eye are stimulated. This teaching is inconsistent with a number of clinical observations. Methods Review of existing literature, reanalysis of data from the investigator's previous experiments, and inductive and deductive reasoning were used to reconcile inconsistencies and present a theory on why torsional movements occur. Results The inconsistencies can be reconciled if one considers that during the dynamic phase of head tilt, there is an alternating series of intorsional and extorsional movements of both eyes. Each eye has slow dynamic compensatory counterrolling phases that serve as torsional “doll's-head” movements to stabilize the image during head tilt. This counterrolling is partially eliminated by a series of anticompensatory torsional saccades in the direction of head tilt, which is in contrast to traditional teaching. Conclusion Dynamic compensatory counterrolling occurs during head tilt. It is largely eliminated by anticompensatory torsional saccades in the opposite direction so that by the end of head tilt only minimal static countertorsion remains. The dynamic compensatory counterrolling motion is necessary to minimize peripheral visual movement during head tilt. The elimination of most of the counterrolling by the end of head tilt is necessary to preserve convergence and stereopsis.

The surgical approach to esotropia with a high AC/A ratio in teenagers should be dichotomized based on whether or not there is satisfactory alignment at distance with the cycloplegic correction in place. If there is not, surgery should target the near angle with glasses on. If there is good alignment at distance, bifocals should be used, and surgery deferred until the patient is approximately 18 years of age. At that time, surgery could be entertained to eliminate the need of a bifocal, by targeting the near angle measured through the distance correction. Surgery for the purpose of eliminating a bifocal in younger teenagers may be unnecessary as 99% of those who maintained satisfactory distance alignment outgrew the need of a bifocal by 18 years of age. However, many still needed a bifocal in their early teenage years.

The day before I was due to retire from 40 years of practice as an academic pediatric ophthalmologist, I delivered the keynote address at the graduation of my department’s residents and fellows. I was in transition; they were in transition. I wanted to choose my words carefully. What would be meaningful to these about-to-become colleagues who were just beginning their careers? Preparing for that presentation offered me an opportunity to review my core values that have evolved over my years in practice. I have always thought deeply about each patient’s experience when they come to see me. Through them, I have learned a lot. At the risk of sounding preachy, I elaborated 9 suggestions on patient care. Spoiler alert: Number 9 was the ultimate secret about caring for patients. For each of the 9, I invoked some wisdom from an outside source (writers, mentors, colleagues, images, patients, and mythology) to add insight about the subject at hand. The following is a summary of my address. One: On talking to patients with wisdom from Mark Twain I have often likened verbal discourse to a scattering of

Strabismus surgery in adults achieves satisfactory alignment with one operation in approximately 80% of patients, depending on the specific nature of the problem. Risks of adult strabismus surgery are relatively low, and serious complications are anecdotal and rare. Even if the strabismus has been long-standing, most adults will experience some improvement in binocular function after strabismus surgery. Consequently, adult strabismus surgery should not be considered merely cosmetic in most cases. In esotropic patients, this improvement typically takes the form of an expansion of binocular visual fields; however, some patients may also regain stereopsis. There are many psychosocial benefits to adult strabismus surgery. This is reflected in the finding that the majority of adults surveyed with strabismus would trade a portion of their life expectancy to be rid of their strabismus.

Traditional teaching is that convergence resulted from accommodation, and this relationship could be used to help manage patients with exotropia by prescribing overcorrecting minus lenses to stimulate accommodative convergence. The relationship between accommodation, convergence, and its role in managing exotropic deviations always seemed straightforward. In this issue of the Journal of AAPOS, Brodsky and colleagues present a creative and thoughtful hypothesis that turns our prior understanding of the relationship between accommodation and convergence on its head. It is based on prior work by Horwood and her coinvestigators. All strabismologists and orthoptists are intimately familiar with how to calculate the accommodation to accommodative convergence ratio (AC/A). Most are less familiar with the concept of the convergence accommodation to convergence ratio (CA/C)—specifically the accommodation that is driven by convergence. Although the common methods for calculating AC/A ratios have proven clinically useful, they are also somewhat flawed, because they are “stimulus” AC/A ratios. This means that the calculation assumes the amount of accommodation occurring is equal to the stimulus to accommodate. So for a gradient AC/A calculation, it is assumed that if one introduces a lens of 1D or 2D power, the patient in fact accommodates 1 D or 2 Ds more, respectively; for a heterophoria calculation based on comparing the change of alignment when fixation changes from 6 M to 1/3 M, it is assumed that the patient is accommodating 3 D more for the latter measurement. This contrasts with “response” AC/ A calculations, which involve measuring how much accommodation actually occurs. Such calculations require equipment not routinely found in the clinic. Similarly, determination of the CA/C requires special equipment which is probably why most clinicians are not accustomed to calculating it. Using excellent methodology, Horwood and Riddell and Horwood and colleagues published some fascinating observations

Objective The purpose of the study was to assess the accuracy of a group of strabismologists applying the Hirschberg and Krimsky tests. Design A clinical trial. Participants Sixteen very experienced strabismologists participated in this study. Intervention The participants were asked to evaluate slides of four different patients using the Hirschberg method and to evaluate two of the four patients with the Krimsky method. The slides included a patient with 25Δ left esotropia, a patient with 25Δ right exotropia, a patient with 80Δ esotropia with a positive angle kappa, and a patient with 75Δ infantile esotropia. Alternate prism and cover testing was performed immediately after the photograph was taken and considered to be the actual deviation of the patient. Main outcome measure Measured was the accuracy in assessing the angle of strabismus. Results With the Hirschberg method, each participant underestimated at least one patient by at least 10Δ. In addition, the participants tended to underestimate both large and small angle esotropic and exotropic patients with greater errors of estimation occurring with larger angles of strabismus. With the Krimsky method, a majority of participants overestimated at least one patient by 10Δ and showed difficulty in appreciating differences of 5Δ. In addition, the authors noted inconsistent responses by each participant. Conclusion The Hirschberg and Krimsky methods are substantially less accurate than the alternate prism and cover test.

Purpose: This was a prospective study assessing the efficacy of the SimulVue bifocal contact lens and the Unilens RGP aspheric multifocal contact lens (Unilens, Largo, Fla.) in the treatment of high accommodative convergence/accommodation (AC/A) esotropia in an adolescent and postadolescent population. Methods: Those patients meeting the inclusion criteria were fit with contact lenses with use of full cycloplegic refraction and later retested by an examiner masked to the previous binocular status. Particular attention was given to the sensory status and the motor fusion of each patient in their bifocal spectacles and then in their bifocal contact lenses. All patients were followed up for at least 6 months after the contact lenses were fitted. Results: Five of the six patients demonstrated larger angles of esophoria or tropia at near with the contact lenses that with bifocal spectacles. The only patient who maintained excellent stereopsis in bifocal contact lenses was the one who normalized her AC/A ratio during this study and no longer required a bifocal in her spectacle correction for fusion. The two patients who initially had no stereopsis but good alignment in spectacle correction had a large esotropia at near fixation with bifocal contact lenses. Conclusions: The SimulVue and Unilens RGP aspheric bifocal contact lenses did not adequately treat adolescent patients who had esotropia associated with a high AC/A ratio.

Purpose: Inferior oblique anteriorization is gaining popularity for the treatment of dissociated vertical divergence associated with inferior oblique overaction. This procedure is based on the theorythat moving the insertion of the inferior oblique muscle anterior to the equator changes its vector of force from one of elevation to one that opposes elevation. The purpose of this investigation is to describe, investigate the cause, and outline treatment for a complication I observed after inferior oblique anteriorization. This postoperative syndrome consists of a motility pattern that resembles marked residual inferior oblique overaction associated with a Y or V pattern. It is probably caused by a restriction of elevation of the abducting eye causing fixation duress, with a resultant upshoot of the contralateral adducting eye. Methods: A retrospective chart review was conducted for all patients on whom I performed bilateral inferior oblique anteriorization for inferior oblique overaction associated with dissociated vertical divergence. Patients in whom this postoperative syndrome developed were compared with those in whom it did not with respect to type and extent of surgery. In addition, cases of patients I treated or examined for this complication but whose inferior oblique anteriorization had been performed by other ophthalmologists were also analyzed. Results: I performed bilateral inferior oblique anteriorization in 77 patients. In 29 patients the inferior oblique muscles were placed level with the insertions of the inferior rectus muscles, in 31 patients they were placed 1 mm anterior to the insertions of the inferior rectus muscles, and in 17 patients they were placed 2 mm anterior. The postoperative syndrome described here developed in two of the 77 patients; both had the inferior oblique muscles placed 2 mm anterior to the insertions of the inferior rectus muscle. These were also the only two patients in this series in whom the new insertion of the inferior oblique muscle was spread out laterally at the time of anteriorization. I have seen an additional six patients in whom this syndrome developed after undergoing operations by other ophthalmologists. In four, the inferior oblique muscles were placed 2 mm anterior to the insertions of the inferior rectus muscles, and in two they were placed 3 mm anterior. Of the eight patients I have observed with this complication, I reoperated on six. The surgical procedure consisted of denervation or extirpation of both inferior oblique muscles in four patients and conversion to standard recessions of the inferior oblique muscles in two patients. In all six patients,the versions were markedly improved and the Y or V pattern was eliminated after reoperation. Conclusions: Anteriorization of the inferior oblique muscles more than 1 mm anterior to the insertions of the inferior rectus muscle may cause a limitation of elevation in abduction, resulting in a Y or V pattern that mimics inferior oblique overaction. This may be more likely to occur if the new insertions of the inferior oblique muscles are spread out laterally at the time of anteriorization.

Background: We have the impression that congenital aberrant innervations are more common than previously reported. Many varieties exist and typically involve the sixth nerve. The most common ocular miswjrings are Duane's syndrome and Marcus Gunn jaw-winking ptosis. The second most common miswiring involves lateral rectus activation in upgaze causing a "Y" pattern exotropia (pseudo inferior oblique overaction). This commonly is confused with inferior oblique overaction but surgery on the obliques does not cure the condition. Lateral rectus recession and elevation are required. Methods: We selected demonstrative cases from our practices to illustrate a variety of congenital aberrant innervations. A literature search for previous reported cases of aberrant innervations was performed. This report is an eclectic collection of observations of individual selected cases. Results: We found aberrant innervations of unusual varieties. These miswirings involve simultaneous firing of the lateral rectus with other muscles, including: the ipsilateral superior rectus, causing "pseudo inferior oblique overaction"; the contralateral lateral rectus, causing synergistic divergence; the ipsilateral superior rectus, in upward saccades only; and the masticatory muscles, causing exotropia with sucking. The third nerve by itself rarely is involved in congenital miswirings, but commonly shows aberrant regeneration after traumatic injuries. We know of no cases of aberrant innervation involving the fourth nerve. Summary: We present cases describing these congenital aberrant innervations and discuss a unifying hypothesis as to their typical involvement of the sixth nerve.

Importance Rectus muscle transposition to treat pattern strabismus or torsion may have an adverse outcome if the surgeon is unaware that it will affect both pattern strabismus and torsion in contradictory ways. Objective To highlight the potential adverse affects of rectus muscle transposition on torsion or pattern strabismus. Design and Participants A retrospective nonblinded medical record review of patients treated by the author between January 1, 1990, and June 30, 2009, in whom rectus muscle transposition to address pattern strabismus worsened torsion, or in whom transposition to address torsion worsened pattern strabismus. The main outcome was a worsening of either torsion or pattern strabismus. Setting A tertiary care university referral center. Intervention Rectus muscle transposition surgery to either treat pattern strabismus or torsion. Main Outcome Measures The presence of new or worsened pattern strabismus or torsion. The outcome measures were determined before data collection began. Results Eight patients were identified by the review, 5 in whom torsion developed because of transposition to address pattern strabismus and 3 in whom pattern strabismus developed after transposition to address torsion. The presence of bifoveal fusion and/or Graves orbitopathy were risk factors for these adverse outcomes. Conclusions and Relevance Rectus muscle transposition to address pattern strabismus may cause torsion, and transposition to address torsion may cause pattern strabismus.

When diplopia occurs after refractive surgery, a systematized approach to diagnosis and treatment is useful. First, determine if the problem is monocular or binocular. Monocular diplopia usually is caused by anterior segment complications and should be referred to an anterior segment surgeon. If the problem is binocular, determine if there is iatrogenic monovision. If monovision was created by the refractive surgery, determine if the double vision is due to fixation switch diplopia. If so, the monovision state needs to be reversed. If fixation switch is not the cause of the symptoms, try "optical rescue". If monovision is not present, check old refraction and motility records, and correct any residual refractive error. Strabismus may need to be treated with surgery, orthoptic exercises, or prisms.

Purpose To evaluate the outcomes of Harada-Ito surgery in correcting various types of torsional diplopia. Methods The medical records of patients who underwent Harada-Ito surgery at two academic institutions were retrospectively reviewed. Data collected included etiology of torsional diplopia, strabismus and torsion measurements, reoperation rate, patient symptoms, and use of prism. Postoperative success was defined as a lack of diplopia in the primary position at distance and downgaze at near with or without prism. Failure was defined as persistent torsional diplopia; partial success was defined as surgical success but with restrictive strabismus in the secondary gaze positions. Results A total of 26 patients (mean age, 46 years; range, 13-89 years) were included. Of these, 17 had superior oblique palsy. The mean follow-up duration was 2 years (range, 2-60 months). The surgical outcome was success in 73% of patients, partial success in 7%, and failure in 19%. All patients with ≤10° of torsion preoperatively obtained surgical success. Patients in the failure group had higher amounts of preoperative torsion compared to the success group ( P = 0.009). The reoperation rate was 23%, including four patients with additional surgery for downgaze esotropia or torsion. One-third of the patients wore a prism immediately after surgery. Conclusions Harada-Ito surgery successfully treated torsional diplopia. Patients with ≤10° of preoperative torsion had a better outcome. Downgaze diplopia was a common reason for additional surgery.

Previous studies have suggested that the location of the equator should be important in determining the site of a "safe maximum recession" of a rectus muscle, and that the location of the equator should be a function of axial length. Exactly where in relationship to the equator a muscle can be safely recessed has never been scientifically determined. Over a 4-year period, we measured axial length on all patients we operated on for strabismus. Using a previously derived formula, we were able to calculate the limbus-to-equator distance, given axial length. Based on our analysis of 28 patients in whom we recessed one or both medial recti posterior to the equator, we believe that recessions of the medial recti up to 1.5 mm posterior to the equator should not produce postoperative medial rectus underaction associated with an overcorrection, but recessions that are further than 1.5 mm posterior to the equator may do so. Recessions to a point greater than 11 mm from the limbus do not appear to be associated with late progressive overcorrection provided that the site of recession is not greater than 1 .5 mm posterior to the equator. Using our previously determined formula for estimating the location of the equator, given axial length, we have generated easy-to-use reference tables for determining the location of the equator in terms of millimeters posterior to the limbus. Also, based on axial length data from 180 strabismus patients, we have generated an algorithm for predicting axial length, given age, and refractive error, which may be useful to the strabismus surgeon in predicting the location of the equator when A-scan ultrasonography is not available.

Insertion slanting recessions or biased resections have been reported to be useful for treating A- and V-pattern strabismus, convergence insufficiency, and convergence excess esotropia. Paradoxically, good results have been reported with methods that are opposite in nature. For example, some researchers would recess the medial rectus muscles and slant the superior pole of each muscle back farther than the inferior pole (Simonsz/von Graefe method) for a V-pattern esotropia, and others would slant the inferior poles back farther (Bietti method). The Simonsz/von Graefe method seems to be based on sound concepts of oculomotor mechanics. The Bietti method has been justified based on a misquoting and misinterpretation of previous work by Alan Scott, MD. Probably neither method contributes substantially to the outcome of strabismus surgery because sarcomere remodeling should rapidly negate the effect of the slanting. Most likely it is the recession or resection itself that affects the outcome.

The paradigm that an "underacting" extraocular muscle is always atrophic or hypoplastic and that an overacting extraocular muscle should always be enlarged leads to inconsistencies with clinical observations. These include findings of "overacting" inferior oblique muscles, superior rectus muscle overaction or contracture syndrome, and normal extraocular muscle diameters in patients with apparent superior oblique muscle palsy, among other clinical entities. These inconsistencies can be reconciled if one accepts the possibility that extraocular muscle contractile activity may reflect a change in neural input to an anatomically normal muscle or that muscle contractile activity may be altered by shifts in fiber type and distribution within a normal-sized muscle. This remodeling may result from vergence adaptation or from any change in neural stimulus to the muscle. There is substantial evidence to suggest that both of these theoretical possibilities may likely occur.

Objective To determine if ocular torsion is a major cause of A and V patterns and oblique muscle overaction or merely a contributing factor. Methods Three separate investigations were conducted. (1) The trajectory of eyes with oblique muscle overaction was plotted across the horizontal field of gaze from videographs to determine if it was linear or curvilinear. (2) The effect of successful Harada-Ito surgery to reduce extorsion on overelevation in adduction in patients with fourth cranial nerve palsy was studied. (3) The effect of successful surgery to treat pattern strabismus in the form of vertical transposition of the horizontal rectus muscles on objective torsion was studied. Results (1) Three eyes with inferior oblique muscle overaction and 2 with superior oblique muscle overaction had a curvilinear rise or fall (respectively) as they moved into adduction. (2) Surgery that successfully decreased extorsion had a negligible effect on overelevation in adduction in 2 patients. (3) Horizontal rectus muscle transposition that was uniformly successful in eliminating A or V patterns consistently caused an increase in objective torsion in all 5 patients studied. Conclusion Ocular torsion may contribute to A or V patterns and overelevation or overdepression in adduction, but it is probably not the major cause of these phenomena.

Purpose To report the surgical treatment of hypertropia coexisting with exotropia, with either vertical offset surgery or additional vertical muscle surgery simultaneous to correction of the exotropia. Methods A total of 35 patients with exotropia and hypertropia who underwent a horizontal muscle surgery for exotropia were included. To determine efficacy in resolving a vertical deviation in patients with exotropia, 28 patients were compared in 2 groups: those who underwent horizontal muscle surgery with vertical offset and those who underwent horizontal muscle surgery with additional vertical muscle surgery. An additional 7 patients who had exotropia and hypertropia but did not undergo vertically corrective surgery were included for comparison. Results Vertical offset of horizontal rectus muscles (4 mm) resulted in 8 Δ correction of the distance hypertropia. Vertical rectus muscle recession used in the treatment of larger hypertropic deviations with exotropia had a 3 Δ correction per 1 mm of recession. Success rates for hypertropia correction were similar between groups, 63% vertical offset and 71% vertical muscle groups; overcorrections occurred in 29% of the vertical muscle group. The vertical correction in both groups was stable in 88% over 6 months postoperatively. Conclusions Vertical offset of the horizontal muscles simultaneous with exotropia correction has a beneficial effect in small-angle hypertropia ( Δ ). Vertical rectus muscle surgery in patients with hypertropia greater than 10 Δ had equivalent success; however, in intermittent exotropia the hypertropia was prone to overcorrection.

The authors tested preoperatively and postoperatively for binocularity with the Bagolini lenses in a series of 359 adults who underwent surgery for long-standing constant strabismus. Eighty-six percent of patients showed a binocular response with the Bagolini lens test almost immediately after surgery. Regardless of the type of deviation present preoperatively, the duration of strabismus, or the depth of amblyopia in the deviating eye (if present), the vast majority of patients developed binocularity. The development of binocularity with the Bagolini lenses after surgery appears to be related to the stability of the postoperative ocular alignment.