Predictors and efficacy of surgical treatment for consecutive exotropia.

PURPOSE: To study the surgical outcomes of consecutive exotropia and predictive factors, and to compare the medial rectus (MR) advancement, lateral rectus (LR) recession, or a combination of both procedures. METHODS: A retrospective study of patients diagnosed with consecutive exotropia that were operated on (2000-2020) were included. The convergence was classified from 0 to +++, with good: ++/+++ and poor: 0/+. A good outcome was considered when the final horizontal deviation was < 10 prism diopters (pd). Follow-up since the surgery and the number of reoperations were registered. RESULTS: A total of 88 cases were analyzed, mean age: 33.98 ± 17.68 years (57.95%: women). The near and distance horizontal deviation mean (±SD) was 34.3 pd (±16.45) and 34.36 pd (±16.33), respectively. MR advancement was performed in 36.36%, LR recession in 27.27%, and a combination of both in 36.36%. Surgery was unilateral in 65.91% (bilateral in 34.09%). A good outcome was obtained in 69.32% and reoperations in 11.36%. The insufficiency convergence was associated with a bad outcome. The near horizontal deviation (P = .006), the vertical deviation (VD) association (P = .036) and the combination of both MR advancement and LR recession (P = .017) were predictors of a bad result. The mean follow-up was 56.5 months ± 57.65. CONCLUSION: A long-term good surgical result was obtained in most patients. The greatest near deviation, the VD association, and the combination of MR advancement and the LR recession were predictive factors for bad results.

Central Mini-plication of the Medial Rectus for Convergence Insufficiency.

Five cases with a mean (± SD) age of 61 (12.02) years are described to study the outcomes of treatment with central mini-plication of the medial rectus (MR) muscles in adult convergence insufficiency with diplopia and near exotropia: mean preoperative deviation: 18 (± 2) pd. Surgical outcome was considered to be favorable when diplopia and symptoms were resolved and final exotropia at near was ≤8 pd at the end of follow-up. A central mini-plication of the medial rectus (MR) muscles was performed in 5 patients (4 unilateral). Overcorrection at distance vision was recorded in 3 cases; this resolved by 3 months postoperatively. There was not overcorrection at near vision in any case. None of the cases operated on had overcorrection at the end of follow-up. The final horizontal deviation was ≤8 pd at near vision, except for 1 case. Symptoms and diplopia resolved in every case but 2/5 required reoperations. The mean follow-up was 8 (2.12) months. Central mini-plication of 1 or 2 medial rectus muscles can improve the symptoms and signs of exotropia associated with convergence insufficiency when exercises and the prisms are rejected by the patients and when these approaches have not solved the problem.

Long term outcomes of strabismus surgery for third nerve palsy / Resultados a largo plazo de la cirugía de estrabismo para parálisis del III par

Purpose: To report long-term outcomes of strabismus surgery for treatment of third nerve palsy. Methods: We performed a 15-year retrospective study of patients who had undergone surgery. We analyzed preoperative mean deviation (at 6 months, 1 year after surgery, and at the end of follow-up), type of surgery, and factors predicting outcomes. A final deviation < 10 prism diopters (pd) was considered a good esthetic outcome, and no diplopia in the primary position at the end of follow-up was considered a good functional outcome. Results: Surgery was performed in 31 cases. Mean age was 36.27 years (women, 51.6%). Total and complete third nerve palsy was recorded in 22.6% and acquired palsy in 80.6%. Mean preoperative horizontal deviation (HD) in primary position was 40.24 pd (near) and 44.29 (distance) and 14.33 pd in vertical deviation (VD). Mean final HD was 8.94pd (near) and 11.35pd (distance), and mean final VD was 6.13. One surgery was performed in 68.9%. A favorable esthetic outcome was obtained in 64.5% and a successful functional outcome in 72.2%. Statistically significant differences were found between near HD (p = 0.019) and distance HD (p = 0.035) at 1 year compared with the end of follow-up and between VD at 6 months and 1 year after surgery (p = 0.03). Mean follow-up was 6.05 years. No specific factors predicted a successful outcome. Conclusions: Esthetic and functional results were similar. No predictors of successful outcome were identified. HD was better 1 year after surgery, and VD improved during follow-up

Objetivo: Reportar los resultados a largo plazo de la cirugía de estrabismo para tratar la parálisis del III par. Métodos: Realizamos un estudio retrospectivo a 15 años, de pacientes sometidos a cirugía. Analizamos la desviación media preoperatoria (a 6 meses, 1 año tras la cirugía, y al final del seguimiento), el tipo de cirugía, y los factores predictivos de los resultados. Se consideró un buen resultado estético una desviación final < 10 dioptrías prismáticas (pd), y un buen resultado funcional la ausencia de diplopía en la posición primaria al final del seguimiento. Resultados: Se practicó cirugía en 31 casos. La edad media fue de 36,27 años (mujeres, 51,6%). Se registró parálisis total y completa del III par en el 22,6% de los casos, y parálisis adquirida en el 80,6%. La desviación horizontal preoperatoria media (DH) en posición primaria fue de 40,24 pd (de cerca) y 44,29 (de lejos), y 14,33pd en desviación vertical (DV). La DH final media fue de 8,94 pd (de cerca) y 11,35 pd (de lejos), y la DV final media fue de 6,13. Se practicó cirugía en el 68,9% de los casos. Se obtuvo un resultado estético favorable en el 64,5% de los casos, y un resultado funcional exitoso en el 72,2%. Se encontraron diferencias estadísticamente significativas entre DH de cerca (p = 0,019) y de lejos (p = 0,035) a 1 año, en comparación con el final del seguimiento, y entre DV a 6 meses y 1 año tras la cirugía (p = 0,03). El seguimiento medio fue de 6,05 años. Ningún factor específico predijo un resultado exitoso. Conclusiones: Los resultados estético y funcional fueron similares. No se identificaron factores predictivos de un resultado exitoso. DH fue mejor 1 año tras la cirugía, y DV mejoró durante el seguimiento

Adjustable Strabismus Surgery under Topical Anesthesia: Alignment in Supine vs Seated Position.

PURPOSE: To compare ocular deviation in the operating room depending on whether the patient is in supine decubitus or seated after single-stage adjustable strabismus surgery under topical anesthesia. MATERIAL AND METHOD: We performed a prospective observational study of 30 patients with horizontal and/or vertical strabismus who underwent single stage adjustable strabismus surgery under topical anesthesia. Both distance and near deviation were evaluated before surgery, during surgery in both positions (seated and supine), and at 1 day, 1 month, and 3 months after surgery. A final horizontal deviation <10 pd and a vertical deviation <5 pd without diplopia was considered to be a good outcome (3 months after surgery). RESULTS: The mean age of the sample was 55 years and 76.7% were women. Most had esotropia (70%). The most frequently used surgical combination was the medial rectus and lateral rectus (36.7%). Surgical adjustment was necessary in 40% of cases. Mean preoperative deviation was 21.9 ± 12.63 pd (distance) and 20.66 ± 4.76 (near). Deviation with the patient supine was 8 ± 8.25 pd (distance) and 7.26 ± 5.81 (near). Deviation with the patient seated was 8.13 pd±8.38 (distance) and 8.5 ± 7.41 (near). There was no significant difference between the positions. Outcome was favorable in 70% of patients; this percentage increased to 83.33% at 1 day, 1 month, and 3 months after surgery. CONCLUSIONS: No statistically significant differences were found between ocular deviations in the seated or supine position in the operating room. Outcome was favorable in most cases 3 months after surgery. Intraoperative ocular deviation was not a predictor of outcome.

Botulinum toxin for treatment of restrictive strabismus / Botox y estrabismo restrictivo

Purpose: To study the types of acquired restrictive strabismus treated in a tertiary hospital and the outcome of treatment with botulinum toxin. Methods: We performed a 10-year retrospective study of patients with restrictive strabismus aged ≥18 years who were treated with botulinum toxin. Treatment was considered successful if the final vertical deviation was ≤5 PD, horizontal deviation ≤10 PD, with no head turn or diplopia. Results: We included 27 cases (mean age, 61.9 years). Horizontal strabismus was diagnosed in 11.1%, vertical in 51.9%, and mixed in 37%. Strabismus was secondary to cataract surgery in 6 cases, high myopia in 6, orbital fractures in 5, retinal surgery in 5, Graves ophthalmopathy in 4, and repair of conjunctival injury in 1 case. Diplopia was diagnosed in all patients, head turn in 33.3%. The initial deviation was 14 PD (range, 2-40), the mean number of injections per patient was 1.6 (range, 1-3), and the mean dose was 9.5 IU (range, 2.5-22.5). At the end of follow-up, diplopia was recorded in 59.3%, head turn in 18.5%, surgical treatment in 51.9%, and need for prism glasses in 14.8%. Outcome was successful in 37% of patients (4 high myopia, 3 orbital fractures, 2 post-surgical retinal detachment, and 1 post-cataract surgery). Mean follow-up was 3 ± 1.8 years. Conclusion: Vertical deviation was observed in half of the sample. The most frequent deviation was secondary to cataract surgery and high myopia. Treatment with botulinum toxin was successful in one-third of the patients at the end of follow-up (AU)

Objetivo: Estudiar los tipos de estrabismo restrictivo adquirido tratados en un hospital terciario, y los resultados del tratamiento utilizando toxina botulínica. Métodos: Realizamos un estudio retrospectivo de diez años en pacientes con estrabismo restrictivo y edades ≥18 años, a quienes se trató con toxina botulínica. El tratamiento se consideró exitoso cuando la desviación vertical final fue ≤5 PD, la desviación horizontal ≤10 PD, y no se produjo torsión ni diplopía. Resultados: Incluimos 27 casos (edad media, 61,9 años). Se diagnosticó estrabismo horizontal en el 11,1% de los casos, vertical en el 51,9%, y mixto en el 37%. El estrabismo fue secundario a: cirugía de cataratas en 6 casos, miopía magna en 6, fracturas orbitales 5, cirugía de la retina en 5, oftalmopatía de Graves en 4, y reparación de lesiones conjuntivales en 1 caso. Se diagnosticó diplopía en todos los pacientes, y tortícolis en el 33,3%. La desviación inicial fue de 14 PD (rango, 2-40), el número medio de inyecciones por paciente fue de 1,6 (rango, 1-3), y la dosis media de 9,5 IU (rango, 2,5-22,5). Al final del seguimiento, se registró diplopía en el 59,3% de los casos, tortícolis en el 18,5%, tratamiento quirúrgico en el 51,9%, y necesidad de gafas prismadas en el 14,8%. El resultado fue exitoso en el 37% de los pacientes (4 miopes magnos, 3 fracturas orbitaria, 2 post-cirugía de desprendimiento de retina, y 1 post-cirugía de cataratas). El seguimiento medio fue de 3 ± 1,8 años. Conclusión: Se observó desviación vertical en la mitad de la muestra. La desviación más frecuente fue secundaria a la cirugía de cataratas y a miopía magna. El tratamiento con toxina botulínica fue exitoso en una tercera parte de los pacientes al finalizar el seguimiento (AU)

Surgical treatment of superior oblique palsy: Predictors of outcome.

PURPOSE: The purpose of this study was to evaluate the incidence and outcome of surgically treated superior oblique palsy (SOP) and the factors involved in its resolution. METHODS: We performed a retrospective study of 76 patients who underwent surgery for SOP. We recorded data from the physical examination and the number and type of procedures performed. Favorable outcome was defined as resolution of or improvement in torticollis (≤5°) and diplopia in primary position (PP) and downgaze or as vertical deviation (VD) <5 prism diopters (pd) in PP and 10 pd in the oblique diagnostic position. RESULTS: Mean age was 33.12 years. Congenital SOP was the most frequent type (65.8%). Mean preoperative VD was 15.89 ± 9.94 pd, decreasing to 3.07 ± 4.36 pd after surgery. Associated horizontal deviation was recorded in 51.32% of cases. The mean number of procedures was 1.37 ± 0.62 (range 1-4), with 69.7% of patients requiring only one procedure. The mean number of muscles operated on was 1.96 ± 1.01 (inferior oblique being the most frequent). A greater reduction in VD after surgery was observed in patients with congenital SOP (P = 0.04). Although none of the factors evaluated influenced surgical outcome, amblyopic patients had a greater risk of reoperation (P = 0.04). A favorable outcome was achieved in 75% of cases. Mean follow-up was 37.08 months. CONCLUSION: Congenital SOP was twice as frequent as acquired SOP and although surgery was successful in most cases, a greater reduction in VD was obtained in congenital cases. Amblyopia was identified as a risk factor for reoperation.

Botulinum toxin for treatment of restrictive strabismus.

PURPOSE: To study the types of acquired restrictive strabismus treated in a tertiary hospital and the outcome of treatment with botulinum toxin. METHODS: We performed a 10-year retrospective study of patients with restrictive strabismus aged ≥18 years who were treated with botulinum toxin. Treatment was considered successful if the final vertical deviation was ≤5 PD, horizontal deviation ≤10 PD, with no head turn or diplopia. RESULTS: We included 27 cases (mean age, 61.9 years). Horizontal strabismus was diagnosed in 11.1%, vertical in 51.9%, and mixed in 37%. Strabismus was secondary to cataract surgery in 6 cases, high myopia in 6, orbital fractures in 5, retinal surgery in 5, Graves ophthalmopathy in 4, and repair of conjunctival injury in 1 case. Diplopia was diagnosed in all patients, head turn in 33.3%. The initial deviation was 14 PD (range, 2-40), the mean number of injections per patient was 1.6 (range, 1-3), and the mean dose was 9.5 IU (range, 2.5-22.5). At the end of follow-up, diplopia was recorded in 59.3%, head turn in 18.5%, surgical treatment in 51.9%, and need for prism glasses in 14.8%. Outcome was successful in 37% of patients (4 high myopia, 3 orbital fractures, 2 post-surgical retinal detachment, and 1 post-cataract surgery). Mean follow-up was 3±1.8 years. CONCLUSION: Vertical deviation was observed in half of the sample. The most frequent deviation was secondary to cataract surgery and high myopia. Treatment with botulinum toxin was successful in one-third of the patients at the end of follow-up.

Fat adherence syndrome following inferior oblique surgery: Treatment and outcomes / Síndrome de adherencia grasa tras cirugía del músculo oblicuo inferior: Tratamiento y resultados

Purpose: Describe surgical treatment and results in a group of patients diagnosed and operated on of fat adherence syndrome following inferior oblique surgery. Patients, material and methods: Retrospective study of 6 cases diagnosed and treated of fat adherence syndrome following inferior oblique surgery. Mean age was 24.67 years (range, 5-41), 3 males, 5 unilateral and 1 bilateral. Mean vertical deviation was 16.16pd (range, 4-25). Esotropia was associated in 4 cases, diplopia in other 2, and anomalous head posture in 3. A good outcome was considered when the final deviation was less than 10pd, with mild limitation of elevation, without anomalous head posture, and a negative duction forced test. Results: The final vertical deviation was 6.83pd (range, 0-14). A 2-4mm inferior rectus recession was performed on 4 patients associated to an inferior oblique surgery/exploration. All patients were operated on once, except 1 case. A good outcome was achieved in 3 patients. Anomalous head posture was resolved in 2 of 3 cases. Diplopia resolved after surgery. Only one case achieved orthophoria. Mean evolution time was 34.83 months (range, 6-78). Conclusion: In the treatment of the fat adherence syndrome, an inferior rectus recession is recommended, associated to inferior oblique exploration or surgery. A good favorable outcome was only achieved in half of the cases with surgical treatment. Limitation of elevation could not be completely resolved in any of the patients (AU)

Objetivo: Describir el tratamiento quirúrgico y los resultados en un grupo de pacientes con diagnóstico de síndrome de adherencia grasa tras una cirugía de oblicuo inferior. Pacientes, material y métodos: Estudio retrospectivo de 6 casos diagnosticados y tratados de síndrome de adherencia grasa tras una cirugía de oblicuo inferior. La edad media fue de 24,67 años (rango, 5-41), 3 varones, 5 cirugías unilaterales y 1 bilateral. La desviación vertical media fue de 16,16 dioptrías prismáticas (rango, 4-25). Se asoció esotropía en cuatro casos, diplopía en dos, y Tortícolis en tres. Se consideró un buen resultado cuando la desviación final fue inferior a 10pd, con leve limitación de la elevación, Tortícolis, y resultado negativo en el test de ducción forzada. Resultados: La desviación vertical final fue de 6,83pd (rango, 0-14). Se realizó una recesión del músculo recto inferior de 2 a 4mm en cuatro pacientes, asociada a una cirugía/exploración del oblicuo inferior. A todos los pacientes se les intervino una sola vez, exceptuando un único caso. Se logró un buen resultado en tres pacientes. La postura de cabeza anómala se resolvió en dos de tres casos. La diplopía se resolvió tras la intervención. En un único caso se logró ortoforia. El tiempo medio de evolución fue de 34,83 meses (rango, 6-78). Conclusión: En el tratamiento del síndrome de adherencia grasa se recomienda la recesión del músculo recto inferior, asociada a una exploración o cirugía del oblicuo inferior. Se logró un resultado favorable y bueno únicamente en la mitad de los casos con tratamiento quirúrgico. La limitación de la elevación no pudo resolverse completamente en ninguno de los pacientes (AU)

Bilateral superior oblique palsy: etiology and therapeutic options.

PURPOSE: To study the causes of bilateral superior oblique palsy (BSOP), treatment with botulinum toxin and/or surgery, and outcome of treatment. METHODS: This was an 11-year retrospective study of patients with BSOP treated with injections of botulinum toxin (Botox), surgery, or both. Treatment was considered successful when anomalous head turn and diplopia in primary gaze position and downgaze resolved. RESULTS: Bilateral superior oblique palsy was diagnosed in 12 patients (8 male; mean age, 29.5 years). Palsy was secondary to a neoplasm in 3 cases and to head trauma in 2. In 2 cases, it was ischemic, in 2 it was congenital; the remaining cases were iatrogenic (hydrocephalus secondary to meningitis, 1), hemorrhagic (1), and idiopathic (1). The clinical manifestations recorded were diplopia (10), anomalous head posture (9), V pattern (12), subjective excyclotorsion (8), and objective excyclotorsion (6). Recovery was spontaneous in 1 case with neoplastic disease. Botox was injected in 8 cases (inferior oblique and/or inferior rectus muscles [successful in 2]), and subsequent surgery was required in 6. Two patients underwent surgery without prior injection of Botox. The most common surgical technique was recession of the inferior oblique muscle (6 patients), either as the only operation or associated with other procedures. The final result was good in 72.72% (8/11). Mean follow-up was 62.6 months (range 9-99 months). CONCLUSIONS: Causes of BSOP were varied (most frequently neoplastic). Botox was effective as the only treatment in 25% (2/8). Outcome was good in a high percentage of cases with Botox, surgery, or both.

Congenital fibrosis of the extraocular muscles: magnetic resonance imaging findings and surgical treatment.

PURPOSE: We analyzed findings of orbital and cranial magnetic resonance imaging (MRI) in patients with congenital fibrosis of the extraocular muscles (CFEOM). We described surgery and its outcome. MATERIAL AND METHOD: Nine out of 10 patients with clinical findings of CFEOM underwent orbital and cranial MRI to perform a study of the extraocular muscles and cranial nerves. A multimodality workstation platform developed by the imaging laboratory of our hospital for PC computer allowed us to visualize and measure the cross sections of the extraocular muscles in a coronal section. Surgery was indicated to resolve strabismus. Outcome was considered favorable if the final deviation was < 10 pd in the primary position without head turn. RESULTS: In 8 cases (6 males, 5 unilateral [3 left eye]), MRI revealed atrophy of at least 1 of the extraocular muscles supplied by the third nerve. Five patients had third nerve aplasia or hypoplasia. Clinical findings were compatible with a probable diagnosis of CFEOM in all 10 patients. Four patients underwent ptosis surgery before being diagnosed with CFEOM. Four patients underwent surgery to correct strabismus and, of these, 2 required multiple interventions (1 needed 4 interventions). Outcome was successful in only 2 cases. CONCLUSION: Orbital and cranial MRI provided useful information about extraocular muscles and cranial nerves in CFEOM. Surgery must be performed on an individual basis; the number of reoperations is high. The outcome of surgery was favorable in half of the cases.

Horizontal rectus surgery in Duane syndrome.

PURPOSE: To study the results of horizontal rectus recession for treatment of Duane syndrome. METHODS: This was a retrospective study of 17 patients with Duane syndrome who underwent strabismus surgery between 2000 and 2008 with medial rectus recession for esotropic deviation or lateral rectus recession for exotropic deviation. The amount of surgery varied individually with the angle of deviation and abnormal head posture. Head turn was graded as mild, moderate, or severe. Botulinum toxin was injected in specific cases. An angle of deviation less than 10 PD and head turn less than 5º after surgery were considered good results. RESULTS: Treatment was successful in 12 cases (70.58%) and unsuccessful in 5 (4 with type I Duane syndrome and one with type III Duane syndrome); in 3 patients the deviation was undercorrected and 2 it was overcorrected. Ipsilateral medial rectus recession of less than 5 mm was performed in 12 patients, although 1 case with a recession of 7 experienced secondary adduction limitation. Abduction limitation was slightly improved in 29.41%. Mean follow-up was 50.59 months. CONCLUSIONS: Moderate horizontal rectus recession is a simple and effective procedure in most patients with Duane syndrome and no secondary duction limitations. The technique only slightly improved abduction in one-third of the cases.

Etiology and treatment of pediatric sixth nerve palsy.

PURPOSE: To describe the causes and treatment of sixth (abducens) nerve palsy in a series of pediatric patients. METHODS: This was a 14-year retrospective study of sixth nerve palsy in children under 14 years of age. Outcomes studied included horizontal deviation, degree of limitation of abduction, and head turn. Patients were treated with botulinum toxin injection at the time of diagnosis; surgery was indicated if treatment with botulinum toxin was unsuccessful. Success was defined as final deviation of orthotropia with no head turn or diplopia. RESULTS: Sixth nerve palsy was diagnosed in 15 patients (10 boys; mean age, 4.1 years) between 1995 and 2008. Involvement was bilateral in 2 cases and unilateral in 13 (7 right eyes). Causes included neoplasm (4 cases), trauma (2), idiopathic (3), congenital (2), viral (2), and inflammatory (1). Neoplastic causes were associated with other neurologic signs. Recovery was spontaneous in 5 cases (2 idiopathic, 1 traumatic, 1 congenital, and 1 inflammatory). Botulinum toxin was successful in 7 of 10 patients treated, with follow-up surgery required in the remaining 3 cases. The final result was good in all cases. In all 15 patients, mean time from diagnosis to resolution was 39 months (range, 5 to 170 months). CONCLUSIONS: Neoplasms were the most frequent cause of sixth nerve palsy in our patient population. Recovery was spontaneous in one third of the patients. Most required treatment with botulinum toxin, which was successful in most cases. Surgery was successful after a single procedure.

Topical anesthesia in strabismus surgery: a review of 101 cases.

PURPOSE: To analyze the results over a 10-year period with a different type of strabismus surgery performed with topical anesthesia, to describe the differences in technique compared with surgery performed with general anesthesia, and to detail current indications and technical changes made according to the experience accrued during these years. METHODS: A total of 101 patients undergoing strabismus surgery with topical anesthesia in a single hospital were analyzed. These patients were randomly selected from a total of 567 patients who had undergone extra-ocular muscle surgery in the past 10 years. RESULTS: A good result was obtained (squint angle < 10 prism diopters and absence of diplopia) in 95% of patients immediately after surgery and in 85% at final follow-up (mean follow-up: 3.1 years). The mean operating time for each muscle was 29 minutes. Surgery was well tolerated in every patient. Conversion to general anesthesia was not necessary in any case. Atropine was used in three patients (3%) because of induction of the vagal reflex. CONCLUSION: Topical anesthesia in strabismus surgery is a useful technique in the treatment of extraocular muscle pathology, with few limitations. Appropriate monitoring by an anesthetist is vital to ensure adequate control of pain and possible side effects and to enable conversion to general anesthesia. The oculocardiac reflex is infrequent. For experienced strabismus surgeons, the total surgical time is comparable with topical and general anesthesia.

Ocular dominance diagnosis and its influence in monovision.

PURPOSE: To analyze the response of normal emmetropic subjects to different ocular dominance tests and to analyze the influence of this response in surgically induced monovision. DESIGN: A prospective study of diagnostic accuracy was carried out to analyze the different tests to determine ocular dominance, without a gold standard test. METHODS: Nine different tests were carried out in a group of 51 emmetropic subjects to determine both motor and sensory ocular dominance. For analysis, patients were divided into two groups according to age. Normal ophthalmologic examination results were the inclusion requirement, with normal binocular vision and good stereoacuity. RESULTS: A significant percentage of uncertain or ambiguous results in all tests performed was found, except in the hole-in-card and kaleidoscope tests. When the tests were compared, two by two, the correlation or equivalence found was low and was much lower if tests were compared three by three. CONCLUSIONS: No clear ocular dominance was found in most studied subjects; instead, there must be a constant alternating balance between both eyes in most emmetropic persons, but not in those with pathologic features. This fact would explain the great variability both between and within different kinds of tests. Also, it would establish that the monovision technique is well tolerated in most patients, with unsuccessful results only in those patients with strong or clear dominance. Consequently, it seems appropriate to evaluate patient's dominance before monovision surgery to exclude those individuals with clear dominance.