Comparison of simultaneous prism and cover test (SPCT) and prism and alternate cover test (PACT) measurements with final power of Press-On prism power dispensed.

PURPOSE: To investigate the association of strabismic angle obtained by simultaneous prism and cover test (SPCT) and prism alternate cover test (PACT) with the final power of Press-On prism used in adults with symptomatic strabismus. METHODS: The medical records of consecutive patients seen by a single orthoptist at an urban, tertiary care hospital over a 36-month period were reviewed retrospectively. All subjects had been prescribed Press-On prism for diplopia after evaluation with SPCT and PACT measurements at distance fixation. Prism dispensed was chosen by the patient using a trial Press-On prism set. RESULTS: A total of 244 charts were reviewed. Of these, 108 adult patients had prism dispensed, and 32 had both SPCT and PACT measurements. Mean SPCT measurement was 7Δ (median, 6Δ; range, 3Δ-14Δ); mean PACT, 13Δ (median, 11Δ; range, 8Δ-20Δ). The mean prism power dispensed was 7Δ (median, 6Δ; range, 1Δ-15Δ); this was not significantly different from mean SPCT (P = 0.35). There was a large difference (6Δ) between mean PACT measurements and mean prism dispensed (P < 0.001). At follow-up of 1 year, 21 patients (66%) remained in prism. Nine patients (4%) elected to undergo eye muscle surgery, 7 with horizontal strabismus, 6 of whom had SPCT measurements of >10Δ and PACT measurements of >15Δ. CONCLUSIONS: Press-On prism power used was more closely tied to the angle of strabismus obtained by SPCT. Overall success rate of Press-On prism was good when the prism power dispensed was close to the SPCT measurement, suggesting that it is reasonable to initiate treatment with a weaker prism, approximating the SPCT measurement, building up only if there are continuing symptoms.

Non-Surgical Treatment of Symptomatic, Oblique Strabismus: A Simplified Approach.

Purpose: Determining the correct power and orientation of prism to be prescribed for patients with symptomatic, oblique-angle strabismus can be challenging and confusing, prone more to clinician gestalt than science or methodology. The author shares a simplified, approach not previously described in the scientific literature that utilizes commercially available equipment and freely available on-line prism calculators for choosing the correct Press-On™ prism power, positioning the prism correctly on the spectacle lens, and ultimately determining the correct prism prescription to be incorporated into the patient's spectacles.

A Survey to Identify Screen Test Usage by Certified Orthoptists Across the United States of America.

PURPOSE: To ascertain the use of screen tests for assessing strabismus under binocular viewing conditions by certified orthoptist colleagues around the United States of America. METHODS: A link to an online survey was distributed to all 440 registered members of the American Association of Certified Orthoptists in early 2022. A total of 135 certified orthoptists responded. RESULTS: Of the 135 respondents, 51% were from a public practice, 36% were private practice and 13% from a mixture of both. A large proportion of respondents did not use binocular screen tests to measure strabismus such as the Lancaster red/green test (85%) or Hess screen test (93%), although one respondent reported using the Harms screen test. Most respondents reported using single or double Maddox rods (75%), synoptophore (44%) and prisms (14%) in their practice to quantify strabismus clinically. CONCLUSION: There is limited use of screen tests in private and public practice in the USA. The ergonomic requirements of such tests are prohibitive to their implementation in modern clinical practice.

Clinical Characteristics of Acquired Diplopia in Adults.

PURPOSE: To describe the common causes of symptomatic strabismus and treatment required to resolve diplopia in adult patients seen by one orthoptist. PATIENTS AND METHODS: Retrospective cross-sectional study of consecutive adult patients 18 years or older seen by one orthoptist over a 3-year period with a chief complaint of double vision. RESULTS: Two hundred twenty-four consecutive adult patients were examined by the author. Chief complaint was double vision, followed by blurred vision, monocular diplopia, and eye strain. Past ocular histories were significant for early-childhood strabismus in 23 patients. Amblyopia was identified in five patients. Hypertension was a medical risk factor most associated with symptomatic strabismus. Cranial nerve paresis was the most common cause of the strabismus followed by benign, age-related divergence insufficiency esotropia. Prism was the most common treatment in 53% of patients followed by Bangerter foil occlusion in 44 patients (20%). Strabismus surgery was recommended in 11 patients (5%). Manifest refraction was successful in resolving symptoms of binocular diplopia in nine heterophoric patients (5%). Opaque pirate style occlusion was not used for any patient in this series. CONCLUSIONS: Symptomatic acquired esotropia was a common type of strabismus encountered by the author and trochlear nerve paresis a common cause of symptomatic strabismus in this retrospective cross-sectional study. Press-On™ or ground-in spectacle prism of 12 prism diopters or less resolved diplopia in 124 patients (55%).

Remote Pediatric Ophthalmology and Adult Strabismus during the COVID-19 Pandemic.

BACKGROUND: The coronavirus (COVID-19) global pandemic has been a poignant reminder of the value of telehealth services to deliver care, especially as a means of reducing the risk of infectious disease transmission caused by close personal contact, decreasing unnecessary travel for medical consultations, and limiting the number of individuals in waiting rooms. The role of telehealth in ophthalmology has historically been limited to store-and-forwarding of images, much like what is used in radiology. PATIENTS AND METHODS: Remote evaluation using two-way audio-video communications over the initial 10-week period of clinic shutdowns. Visual acuity (VA) measurement was attempted using a printed single surrounded HOTV or Snellen chart. The VA measurement of fellow eyes was compared to the prior in person clinical visit. External and strabismus examinations were also conducted. RESULTS: Fifty-eight patients were evaluated with a mean age 12.5 years (range 5 months to 82 years). Twenty of 58 (34%) were younger than 5 years of age. Reasons for evaluation were strabismus in 26 patients (45%), refractive error in 25 (43%), and amblyopia in 10 patients (19%). Recognition visual acuity was obtained in 69% (40 of 58), including every patient older than 5 years of age. Nine children from 2 to 5 years of age (mean 3 years) were unable to perform HOTV VA testing. Of nine children unable to do complete VA testing, five had been premature and seven had developmental delay. There was a mean bias of -0.12 logMAR in favor of the prior in office test in the right eyes of 21 non-amblyopic patients. The 95% limits of agreement between the in-person visit and the subsequent telehealth video visit logMAR VA were +0.20 logMAR upper limit, -0.44 logMAR lower limit. CONCLUSIONS: Telehealth video visits provided basic ophthalmic information in patients who are physically incapable to come to the office, leading to improved triage. Vision could be tested remotely in young children, but we found substantial variability in the measurement of clinically normal eyes. Improvements in the reliability of at-home visual acuity testing are needed.

A Randomized Clinical Trial of Immediate versus Delayed Glasses for Moderate Hyperopia in 1- and 2-Year-Olds.

PURPOSE: Two strategies were compared for managing moderate hyperopia without manifest strabismus among 1- and 2-year-old children: (1) immediate prescription of glasses versus (2) observation without glasses unless reduced distance visual acuity (VA), reduced stereoacuity, or manifest strabismus. DESIGN: Prospective randomized clinical trial. PARTICIPANTS: A total of 130 children aged 1 to 2 years with hyperopia between +3.00 diopters (D) and +6.00 D spherical equivalent (SE) in at least 1 eye, anisometropia ≤1.50 D SE, and astigmatism ≤1.50 D based on cycloplegic refraction and no manifest strabismus. METHODS: Participants were randomly assigned to glasses (1.00 D less than full cycloplegic hyperopia) versus observation and followed every 6 months for 3 years. Glasses were prescribed to those assigned to observation if they met prespecified deterioration criteria of distance VA or near stereoacuity below age norms, or development of manifest strabismus. MAIN OUTCOME MEASURES: At the 3-year primary outcome examination, participants were classified as failing the randomized management regimen if distance VA or stereoacuity was below age norms or manifest strabismus was observed (each with and without correction in trial frames, confirmed by masked retest, irrespective of whether deterioration had occurred previously), or if strabismus surgery had been performed. RESULTS: Of the 106 participants (82%) completing the 3-year primary outcome examination, failure occurred in 11 (21%) of 53 in the glasses group and 18 (34%) of 53 in the observation group (difference = -13%; 95% confidence interval [CI], -31 to 4; P = 0.14). Sixty-two percent (95% CI, 49-74) in the observation group and 34% (95% CI, 23-48) in the glasses group met deterioration criteria (requiring glasses if not wearing). CONCLUSIONS: For 1- and 2-year-olds with uncorrected moderate hyperopia (+3.00 D to +6.00 D SE), our estimates of failure, after 3 years of 6-month follow-ups, are inconclusive and consistent with a small to moderate benefit or no benefit of immediate prescription of glasses compared with careful observation (with glasses only if deteriorated).

Sensorimotor Characteristics of Neuro-Ophthalmology and Oculo-Plastics Patients.

BACKGROUND AND PURPOSE: Certified orthoptists are routinely required, as a standard component of outpatient care, to examine and identify the cause of double vision described by neuro-ophthalmology and oculo-plastics patients. Peer-reviewed articles in the strabismus literature describing the significance of this role of the orthoptists, especially in more complex cases of strabismus, do exist, but are outdated. The importance of creating a differential diagnosis in the understanding of the disease process is a well-recognized component of medical education and modern medicine. PATIENTS AND METHOD: This work was a retrospective chart review and descriptive study of the most common clinical characteristics of adult neuro-ophthalmology and oculo-plastics patients seen over a 9-year period by an orthoptist in a large, urban academic institution in the United States. History and clinical data obtained included demographic information; whether the subjects were neuro-ophthalmology or oculo-plastic patients or both; chief complaint; past medical history and associated medical risk factors; past ocular history of strabismus or amblyopia; whether reported diplopia was monocular or binocular; visual acuities; sensorimotor examination and fusion status information; presence or absence of ptosis; pupil size and reactivity; basic accommodative function; orthoptist and physician diagnoses; and suggested treatment of diplopia. RESULTS: Five hundred seventy-five subjects were identified based on inclusion criteria. Racial demographics matched that of the state of Maryland, with the majority of the patients being Caucasian. The minority were of Hispanic origin. Ninety-one percent of the study cohort was referred by the department of neuro-ophthalmology at the institution. Hypertension was a statistically significant medical risk factor for acquired strabismus and diplopia in this adult cohort. Etiology for the strabismus and associated diplopia suggested by the orthoptist was in close agreement with the final diagnosis made by the referring physician. Pupil-sparing oculomotor palsy (third cranial nerve, CN3) occurred as frequently as pupil-involving CN3, with tumor occurring more frequently as an etiology than aneurysm in both groups. Trochlear nerve palsy (CN4) was more often associated with hydrocephalus than abducens nerve palsy (CN6), and trauma remained a common association with acquired CN4 palsy. In patients with thyroid eye disease (TED), eso- and exo-deviations occurred with similar frequency. As has been reported in the literature, concomitant myasthenia gravis (MG) remained rare in these patients, although occurring with similar frequency in patients with both types of horizontal deviation. In patients with ptosis, asymmetry was not statistically more predictive of MG than symmetry. Prism was used most frequently, followed by surgery, to address diplopia symptoms. Lastly, there was a statistically significant association of acquired strabismus and diplopia in female subjects with breast cancer and no past ocular history of childhood strabismus or amblyopia. CONCLUSION: The thorough assessment of sensorimotor function, fusion, and visual acuity provided by the orthoptist is an important clinical adjunct in developing the differential required to make an accurate final diagnosis, which sometimes may not subscribe to accepted clinical norms reported in the literature. The orthoptist also plays an important role in the nonsurgical treatment of acquired diplopia due to strabismus. Fresnel Press-On™ or ground-in spectacle prism was a commonly used treatment for diplopia.

DVD--a conceptual, clinical, and surgical overview.

Dissociated vertical deviation (DVD) is a slow, disconjugate hypertropic deviation of a nonfixating eye. It is usually bilateral, asymmetrical, and often associated with congenital esotropia. The deviating eye elevates, abducts, and excyclotorts. This type of strabismus is often variable, making measurement and clinical quantification difficult. Specific knowledge of the mechanisms and characteristics of the dissociated deviation are required for proper assessment and effective treatment. There is currently no consensus on the mechanisms and pathophysiology of DVD. In this workshop, participants discuss the characteristics and most current methods for assessing and quantifying the deviation and explore the potential etiologies, clinical characteristics, and indications for surgical intervention and nonsurgical management of DVD.

Distance versus near visual acuity in amblyopia.

PURPOSE: There are conflicting reports about whether distance and near visual acuity are similar in eyes with amblyopia. The purpose of this study is to compare monocular distance visual acuity with near visual acuity in amblyopic eyes of children. METHODS: Subjects 2 to 6 years of age were evaluated in a randomized trial of amblyopia therapy for moderate amblyopia (20/40 to 20/80) due to anisometropia, strabismus, or both. Prior to initiating the protocol-prescribed therapy, subjects had best-corrected visual acuity measured with standardized protocols at 3 meters and 0.4 meters using single-surrounded HOTV optotypes. RESULTS: A total of 129 subjects were included. The mean amblyopic eye visual acuity was similar at distance and near (mean, 0.45 logMAR at distance versus 0.45 logMAR at near; mean difference, +0.00, 95% CI, -0.03 to 0.03). Of the 129 subjects, 86 (67%) tested within 1 line at distance and near; 19 (15%) tested more than 1 logMAR line better at distance, and 24 (19%) tested more than 1 logMAR line better at near. The mean visual acuity difference between distance and near did not differ by cause of amblyopia, age, or spherical equivalent refractive error. CONCLUSIONS: We found no systematic difference between distance and near visual acuity in 2- to 6-year-old children with moderate amblyopia associated with strabismus and/or anisometropia. Individual differences between distance and near visual acuity are likely due to test-retest variability.

Silent sinus syndrome causing cyclovertical diplopia masquerading as superior oblique paresis in the fellow eye.

Silent sinus syndrome is an insidious maxillary sinus inflammatory disease causing a lowering, thinning, or even absorption of the orbital floor. Patients usually present with progressive enophthalmos and hypoglobus. We report a 41-year-old man with silent sinus syndrome who presented with cyclovertical diplopia masquerading as superior oblique muscle paresis in the fellow eye. Inferior oblique myectomy in the fellow eye resulted in excellent alignment.

The lancaster red-green test.

Walter Brackett Lancaster introduced his red-green test in 1939. He felt that any good test of heterophoria should assess the fixation of each eye, simultaneously, without the corrupting influence of a fusion stimulus. His basic concept was to utilize the strength of the cover test-namely, accuracy in measuring ocular deviations-while at the same time devising a way to "measure quickly and accurately the position of the covered eye when the other eye is fixating" in the diagnostic positions of gaze. The Lancaster Red-Green test is a convenient tool for assessing ocular misalignment in patients with paralytic or restrictive strabismus. It is a binocular, dissociative, subjective test that can quickly and accurately measure strabismus in the nine diagnostic positions of gaze. Comitancy, primary and secondary deviations, and torsional misalignment can all be detected and graphically portrayed.