Steven M. Archer

Stereopsis and binocular vision after surgery for unilateral infantile cataract

PURPOSE To assess the prevalence and level of binocular function in children with unilateral congenital or very early infantile cataract. METHODS We retrospectively reviewed the charts of all patients with unilateral congenital or very early infantile cataract who underwent operation before 4 months of age, at the W. K. Kellogg Eye Center/University of Michigan Hospitals, from 1985 to 1995. Amblyopia was treated with a reduced patching schedule consisting of 1 hour per day per month of age for the first 6 months of life, in an attempt to improve binocular function by allowing more hours of binocular interaction during the presumed critical period for development of binocular cortical pathways. RESULTS Thirteen patients met the inclusion criteria. Seven patients had persistent hyperplastic primary vitreous (PHPV) cataract and 6 had non-PHPV cataract. Overall, visual acuity of 20/80 or better developed in 69% of patients; 100% of eyes with non-PHPV cataract achieved visual acuity of 20/60 or better. Stereopsis of 400 arc seconds or better was detectable in 62% of patients, including 3 with PHPV cataract and 3 who required strabismus surgery in the first year of life. Three children had better than 150 arc seconds of stereopsis. The incidence of large-angle strabismus was 54%. CONCLUSIONS Binocular cooperation, including gross and fine stereopsis, can develop in children with unilateral aphakia as a result of early removal of infantile cataracts. A less-strenuous patching schedule than has been historically advocated may foster this process, while restoring and maintaining good central visual acuity in patients with excellent compliance with contact lens and occlusion regimens.

Optical Characterization of Bangerter Foils

PURPOSE Optical penalization is emerging as an alternative to patching for the treatment of amblyopia. Bangerter foils offer a form of optical penalization that is distinctly different from standard techniques making use of atropine or spectacle lens manipulation, or both, to produce defocus. The authors examined the optical properties of Bangerter foils and compared them with the effect of defocus. METHODS Bangerter foils were evaluated on an optical bench to calculate point spread and modulation transfer functions. Retinal images through the foils were also simulated and qualitatively compared with those with defocus and Gaussian blur. Subjective visual acuity and contrast sensitivity were compared in two subjects wearing spectacles with foils and with simple defocus. RESULTS The optical characteristics of the Bangerter foils do not correspond well with their labeled density designation. Bangerter foils and defocus affect the modulation transfer function similarly, with more attenuation of mid-range spatial frequencies than low spatial frequencies. However, Bangerter foils do not exhibit spurious resolution and phase shifts, as does defocus. CONCLUSIONS The blur resulting from Bangerter filters is qualitatively different from defocus. Whether this difference is of any consequence when these two methods of optical penalization are used for amblyopia treatment remains to be investigated.

Effect of axial length and keratometry measurement error on intraocular lens implant power prediction formulas in pediatric patients.

PURPOSE To examine the relationship between axial length and keratometry measurement errors and intraocular lens (IOL) power calculations for pediatric eyes. METHODS The sensitivity of IOL power calculation to errors in axial length and keratometry measurements was computed as a function of axial length and keratometry for the SRK II, Hoffer Q, Holladay I, SRK/T, and Haigis formulas. RESULTS The sensitivity of the IOL power calculation to an axial length measurement error is increased at 4 to 14 D/mm error in axial length in children compared with 3 to 4 D/mm error in axial length in adults. The error in calculation is 0.8 to 1.3 D/D error in keratometry measurement for both children and adults. CONCLUSIONS Axial length measurement errors in pediatric eyes may lead to large errors in IOL power calculations.

Bangerter foils in the treatment of moderate amblyopia.

Purpose To investigate Bangerter foils as an alternative method of treating amblyopia. Patients and Methods Thirty-three amblyopic children with vision of 20/60 or better in the amblyopic eye were treated with Bangerter foils. The foils were used as primary treatment in 15 patients and after initial occlusion therapy in 18 patients. The Bangerter foils were worn full-time on the spectacle lens in front of the dominant eye. The density of the foil was decreased as vision improved. Results Thirty-one patients had good compliance. All of these achieved 20/30 vision or better in the amblyopic eye with an average of 1.4 years follow-up after cessation of treatment. Over half retained 20/20 acuity. Conclusion Bangerter foils are effective for treatment of amblyopia with 20/60 or better vision. They can be used as primary treatment or as alternative treatment in cases where patching therapy is not providing further benefit.

Measurement of Low Vision in Children and Infants

The authors evaluated a preferential looking technique (Teller acuity cards) and a set of gross behavioral indicators (visual function battery) for the ability to rank visually impaired children and infants on the basis of their visual function. Fourteen older children with a diagnosis of cicatricial retinopathy of prematurity who were capable of giving Snellen acuities and a group of 31 preverbal infants with decreased vision due to a variety of causes were tested. Teller acuity card and visual function battery findings were highly correlated with each other (and with Snellen acuities in the older group); however, the Teller acuity cards provided better discrimination in the moderately visually impaired range, whereas the visual function battery was better in the severely impaired range. It is concluded that, in children and infants, visual function over the entire spectrum of low vision can be characterized by using a combination of the Teller acuity cards and the visual function battery.

Children with Exotropia Responsive to Spectacle Correction of Hyperopia

A series of seven exotropic children (aged 2 to 10 years) had resolution of exotropia after spectacle correction of hyperopia. Their hyperopic correction ranged from 3.00 to 7.00 diopters. Six had intermittent exotropia, which became small-angle esophoria after spectacle correction. In one patient with apparently no fusion, spectacle correction converted constant exotropia to small esotropia in the monofixational range. In all patients, Worth 4-dot and Titmus Stereo Test results, when obtainable, indicated an improvement in binocular sensory status after correction of the hyperopia. We conclude that a trial of spectacle correction is warranted in exotropic children with severe hyperopia and in those with moderate hyperopia and a low accommodative convergence/accommodation ratio or evidence of hypoaccommodation.

The effect of medial versus lateral rectus muscle surgery on distance-near incomitance

PURPOSE For strabismus with distance-near incomitance (unequal distance and near deviations), it is customary to select lateral or medial rectus muscle surgery based on whether the deviation is greater at distance or near. The purpose of this study is to examine how this choice between medial and lateral rectus muscle surgery affects distance-near incomitance. METHODS Preoperative and postoperative distance and near deviations were obtained from a retrospective review of medical records of consecutive patients who underwent bilateral medial or lateral rectus muscle recessions or resections between January 1, 2000, and June 30, 2007. RESULTS A total of 626 procedures were identified. After exclusions, initial procedures included 267 medial rectus muscle recessions that produced an average of 9% more exoshift at near and 159 lateral rectus muscle recessions that produced an average of 34% more esoshift at distance. A larger preoperative distance-near incomitance is associated with a greater reduction in distance-near incomitance with surgery, irrespective of which muscles undergo surgery. Recessions for consecutive deviations and resections for residual deviations exhibited a similar pattern. CONCLUSIONS Esotropia tends to be greater at near and exotropia greater at distance fixation. The apparent greater effect of medial rectus muscle surgery on near deviation and lateral rectus muscle surgery on distance deviation is probably an artifact of this difference in preoperative characteristics. Whether a deviation is greater with distance or near fixation may not be a major consideration in choosing between medial or lateral rectus muscle surgery.

Management of binocular diplopia due to maculopathy with combined bangerter filter and fresnel prism.

Purpose To describe treatment of binocular diplopia due to maculopathy with a combination of Bangerter foil and Fresnel prism. Methods and Case Report A protocol for prescribing a combination of Bangerter foil and Fresnel prism is described. A series of three patients in whom a Bangerter foil or prism alone were ineffective for binocular diplopia due to maculopathy, along with a detailed case report of one of these patients, illustrates how a combination of both were used to treat the diplopia. Conclusions Fogging is presumed to relieve binocular diplopia due to maculopathy by inducing a functional central scotoma in the affected eye. In some patients, prism correction is needed in addition to a Bangerter foil to eliminate diplopia, possibly by impoving superimposition of the scotoma in the affected eye and the fovea of the sound eye.

Microcephaly, Jejunal Atresia, Aberrant Right Bronchus, Ocular Anomalies, and XY Sex Reversal

We present a patient with microcephaly, jejunal atresia, aberrant right tracheobronchial tree, mild left blepharoptosis, and corectopia (irregular pupil), left sectoral iris stromal hypoplasia and peripheral anterior synechia, and 46,XY sex reversal. Testosterone and dihydrotestosterone (DHT) levels were within normal limits for a male infant at 3 weeks of age. Gonadectomy at age 18 months revealed immature testis tissue and no evidence of Müllerian structures. PCR amplification of the androgen receptor (AR) gene and flanking genomic regions revealed no evidence for deletion. Array‐comparative genomic hybridization (array‐CGH) for assessment of gene dosage in other regions of the genome was normal. This patient represents a multiple anomaly disorder similar to intestinal atresia—ocular anomalies—microcephaly syndrome (MIM#243605) but incorporating 46,XY sex reversal with testicular tissue, demonstrating a defect in the sexual differentiation pathway.

Recurrent orbital schwannomas: clinical course and histopathologic correlation

BackgroundSchwannomas are slow-growing typically encapsulated tumors composed of differentiated Schwann cells, the primary class of peripheral glial cells. Complete excision is the treatment of choice for orbital schwannomas that cause pain, disfigurement, diplopia, or optic neuropathy. The presence of multiple schwannomas in a single patient suggests possible association with neurofibromatosis type 2 (NF2) or schwannomatosis.Case presentationWe present 2 patients who experienced recurrent orbital schwannoma without evidence for neurofibromatosis. The recurrence in one patient, a 59-year old man, occurred 6 years after complete excision of the initial tumor. This recurrence consisted of 2 independent tumors in the same orbit. The recurrence in the second patient, a 5 year-old girl, occurred multiple times within days to weeks of partial excisions until eventually a complete excision was performed.ConclusionThe clinical history, histopathologic features and particularly the intraoperative findings suggest that the 59 year old man suffers from orbital schwannomatosis, while the rapid recurrence in the second patient correlated with the cellular features of her plexiform schwannoma. Hence, the recurrence in each patient is linked to a different etiology, with implications for treatment and patient counseling given the difficulty in treating orbital schwannomatosis. To our knowledge, this is the first description of isolated orbital schwannomatosis.