Feasibility of a clinical trial of vision therapy for treatment of amblyopia.

PURPOSE: We conducted a pilot randomized clinical trial of office-based active vision therapy for the treatment of childhood amblyopia to determine the feasibility of conducting a full-scale randomized clinical trial. METHODS: A training and certification program and manual of procedures were developed to certify therapists to administer a standardized vision therapy program in ophthalmology and optometry offices consisting of weekly visits for 16 weeks. Nineteen children, aged 7 to less than 13 years, with amblyopia (20/40-20/100) were randomly assigned to receive either 2 hours of daily patching with active vision therapy or 2 hours of daily patching with placebo vision therapy. RESULTS: Therapists in diverse practice settings were successfully trained and certified to perform standardized vision therapy in strict adherence with protocol. Subjects completed 85% of required weekly in-office vision therapy visits. Eligibility criteria based on age, visual acuity, and stereoacuity, designed to identify children able to complete a standardized vision therapy program and judged likely to benefit from this treatment, led to a high proportion of screened subjects being judged ineligible, resulting in insufficient recruitment. There were difficulties in retrieving adherence data for the computerized home therapy procedures. CONCLUSIONS: This study demonstrated that a 16-week treatment trial of vision therapy was feasible with respect to maintaining protocol adherence; however, recruitment under the proposed eligibility criteria, necessitated by the standardized approach to vision therapy, was not successful. A randomized clinical trial of in-office vision therapy for the treatment of amblyopia would require broadening of the eligibility criteria and improved methods to gather objective data regarding the home therapy. A more flexible approach that customizes vision therapy based on subject age, visual acuity, and stereopsis might be required to allow enrollment of a broader group of subjects.

Retinopathy of prematurity in infants weighing less than 500 grams at birth enrolled in the early treatment for retinopathy of prematurity study.

PURPOSE: To describe patient characteristics, classification, and onset of prethreshold retinopathy of prematurity (ROP), and ocular findings at 6 months corrected age in infants with birth weights <500 g who were enrolled in the Early Treatment for Retinopathy of Prematurity (ETROP) Study. DESIGN: Multicenter randomized clinical trial. PARTICIPANTS: Sixty-three infants with birth weights <500 g who developed ROP and were enrolled in the ETROP Study. METHODS: Infants <1251 g at birth were logged at 26 study centers from October 1, 2000, to September 30, 2002, and underwent examinations for ROP. Infants who developed ROP and whose parents/legal guardians consented were enrolled in the ETROP Study. Infants who developed high-risk prethreshold ROP were randomized; 1 eye was treated early with peripheral retinal ablation and the other eye was managed conventionally, or, in asymmetric cases, the high-risk eye was randomized to early peripheral retinal ablation or conventional management. All eyes reaching prethreshold ROP were examined when infants reached 6 months corrected age. MAIN OUTCOME MEASURES: Retinopathy of prematurity incidence, characteristics, and ocular findings among participants. RESULTS: Thirty-four infants reached prethreshold or worse severity in 1 or both eyes. Retinopathy of prematurity was located in zone I in 43.3% of all prethreshold eyes, and plus disease was present in 46.7%. Median postmenstrual age for diagnosis of all prethreshold ROP was 36.1 weeks, but earlier (35.1 weeks) for eyes that developed high-risk prethreshold ROP. In the 27 surviving infants with prethreshold ROP, ophthalmic examination at 6 months corrected age showed a normal posterior pole in 22 (81.5%), a favorable structural outcome with posterior pole abnormalities in 4 (14.8%), and an unfavorable structural outcome (stage 4B) in 1 (3.7%). One infant developed amblyopia, 4 infants developed nystagmus, 4 infants developed strabismus, and 8 infants developed myopia >-5.00 diopters. CONCLUSIONS: This is the first report on characteristics of prethreshold ROP in infants with birth weights <500 g. These infants are at high risk for developing prethreshold ROP, although many initially achieve a favorable structural outcome. They are at risk of developing strabismus, nystagmus, high myopia, and abnormal retinal structure and should therefore receive continued long-term follow-up. FINANCIAL DISCLOSURE(S): The author(s) have no proprietary or commercial interest in any materials discussed in this article.

Epidemiology of surgical strabismus in Saudi Arabia.

PURPOSE: To describe the types and age differences of surgical strabismus. METHODS: Records of 4,886 strabismus patients who underwent surgery at the King Khaled Eye Specialist Hospital in Riyadh, Saudi Arabia from 1982 to 1996 were analyzed. Demographic and clinical data were collected from all patients as a retrospective case series. The percentages and ratios of various types of strabismus were correlated with age and gender. RESULTS: The average age of our patients was 13.2 years (range 4 months to 82 years). Esotropia was the most common type of strabismus (69.3%), while exotropia was less common (26.9%). Of patients undergoing esotropia correction, infantile esotropia and partially accommodative esotropia were equally common; non-accommodative was less common. Constant exotropia was almost three times more common than intermittent exotropia. The rate of sensory strabismus was high, 20.8% of all patients in the series, with a slight preponderance of sensory esotropia. CONCLUSIONS: The ratio of esotropia to exotropia in our study is comparable to previous studies done in predominantly European and Middle Eastern populations. Surgical esotropia decreased with age while surgical exotropia increased. Overall, our rates of sensory strabismus were much higher than previously reported, even if we compare only the younger patients.

A review of primary care vision screening.

INTRODUCTION AND BACKGROUND: Preschool vision screening (PVS) is an essential component of detecting treatable vision loss in young children. Many state screening programs are struggling to cope with unfunded mandates. Neither school nor community screenings are standardized, and often result in both under- and over-referrals. METHOD: Compared to hearing and dental screenings, PVS is not being performed in the primary care office. Why is this, and what could be done to change the situation? RESULTS: To be effective, PVS relies on the participation of the primary care office that already has a rapport with the child and a relationship with the child's family within the medical home. Vision screening can be included as part of wellness testing strategies. CONCLUSION: The current state of PVS as evidenced by the literature points to a lack of education and training in the primary care arena. Orthoptists are ideally trained to perform accurate PVS and to emphasize its importance. Because of time constraints however, they might be better utilized as a teaching liaison between ophthalmology and pediatric / family practice training programs.

Frequency doubling technology perimetry in normal children.

PURPOSE: To test visual field thresholds of normal children with frequency doubling technology (FDT) perimetry to quantify testing times and reliability characteristics in a pediatric population and to determine whether current methods of stratifying adult threshold values need revision for children. DESIGN: Prospective cross-sectional study. METHODS: Ninety-four children, ages 5 to 17 years, were recruited from local pediatric clinics and the general community and were tested at one center. Children likely to have abnormal visual fields or abnormal test taking ability because of ophthalmic, neurologic, or behavioral problems were excluded. Children were asked to perform a threshold FDT visual field with each of their eyes. Threshold results were gathered, analyzed, and compared with the standards that have been established for tests in adults. Results were validated by testing a further 72 children, with the same protocol, at a different center. RESULTS: For children older than 14 years, threshold mean deviation values were within normal limits according to the adult normative database that is used currently in FDT perimetry. Below 15 years of age, mean deviations for normal children decreased with decreasing age. The best linear fit was given by a mean deviation of -11.43 +/- 0.82 dB x age (R2 = 0.18; P < 10(-5)). CONCLUSION: This research establishes a normative model for pediatric visual field testing with FDT and, by a comparison of threshold results for normal children to established adult norms, provides evidence that parameters for normal sensitivity must be revised for children younger than 15 years.

The effect of amblyopia therapy on ocular alignment.

PURPOSE: We sought to describe the change in ocular alignment at 2 years after treatment of amblyopia in children younger than 7 years of age at enrollment. METHODS: A randomized clinical trial of patching versus atropine for 6 months followed by standard clinical care for 18 months was conducted in 357 children with anisometropic, strabismic, or combined amblyopia (20/40-20/100) whose ages ranged from 3 to younger than 7 years at enrollment. Ocular alignment was evaluated at enrollment and after 2 years of follow-up. RESULTS: At enrollment when tested at distance fixation, 161 (45%) children were orthotropic, 91 (25%) had a microtropia (1-8 Delta), and 105 (29%) had a heterotropia >8 Delta. Of the 161 patients with no strabismus, similar proportions of patients initially assigned to the patching and atropine groups developed new strabismus by 2 years (18% vs. 16%, P = 0.84). Of these cases of new strabismus, only 2 patients in the patching group and 3 patients in the atropine group developed a deviation that was greater than 8 Delta. Microtropia at enrollment progressed to a deviation greater than 8 Delta with similar frequency in both treatment groups (13% vs. 15%, P = 1.00). Of the 105 patients with strabismus greater than 8 Delta at enrollment, 13% of those in the patching group and 16% of those in the atropine group improved to orthotropia without strabismus surgery. Strabismus surgery was performed in 32 patients during the 2-year study period. CONCLUSIONS: Patients who had amblyopia treatment with patching or atropine for 6 months followed by standard clinical care were found to have similar rates of deterioration and improvement of ocular alignment. When parents begin amblyopia treatment for children without strabismus, they should be warned of the possibility of development of strabismus, although it is most often a small angle deviation. Strabismus resolved after amblyopia therapy in some cases.

Strabismus surgery for adults: a report by the American Academy of Ophthalmology.

OBJECTIVE: To describe the effectiveness and safety of surgical treatment of adult patients with strabismus, and to review the reported functional benefits and complications of strabismus surgery for adults. METHODS: A literature search was conducted in September 2001. It was repeated and updated in April 2003, with retrieval of relevant citations. Panel members reviewed the articles and rated them according to their relevance to the topic and methodology. RESULTS: The literature search identified 49 reports that describe the surgical treatment of strabismus in adult patients and meet predetermined review criteria. Of these reports, 2 were of randomized controlled trials, and 1 addressed the primary objective of this review. In this randomized study of adults with strabismus, direct comparison of surgical correction with botulinum toxin A chemodenervation indicated that surgical treatment was superior to botulinum toxin A in realigning the eyes (76.9% vs. 29.4%, P = 0.027). Several large case series of adults with strabismus (level III evidence) with successful surgical realignment rates of 68% to 85% have been reported. Functional benefits of surgical treatment are reported in many patients. These include elimination of diplopia, development of binocular fusion, expansion of binocular visual fields, and improvement of head position. Surgical complications, including new, postoperative diplopia (1%-14%) or scleral perforation (0.8%-1.8%), occur in a minority of patients. Unplanned reoperations (subsequent strabismus procedures that were not anticipated as part of a staged treatment) were needed in up to 21% of patients in large case series of comitant strabismus, and in up to 50% of patients with thyroid ophthalmopathy. CONCLUSIONS: Despite the paucity of level I evidence from randomized controlled trials, the existing literature suggests that surgical treatment of adults with strabismus is safe and effective in improving ocular alignment. In many cases it improves visual function, based largely on level III evidence. Risks include unplanned reoperation, postoperative diplopia, and scleral perforation. Additional level I studies of surgical treatment of adult patients would help to document the effectiveness and substantiate the safety of this treatment.

Intraocular lens implantation during infancy: perceptions of parents and the American Association for Pediatric Ophthalmology and Strabismus members.

BACKGROUND: To determine whether a randomized clinical trial, the Infant Aphakia Treatment Study, comparing intraocular lens (IOL) implantation with contact lens (CL) correction for infants with a unilateral congenital cataract (UCC), is feasible by (1) ascertaining whether American Association for Pediatric Ophthalmology and Strabismus (AAPOS) members have equipoise regarding these two treatments and (2) evaluating the willingness of parents to agree to randomization. METHODS: All AAPOS members were surveyed in August 1997 and again in June 2001 regarding their use of CLs and IOL implants to correct infants vision after unilateral cataract surgery. In addition, a pilot study was begun in March 2002 to evaluate the safety of IOL implantation during infancy and the willingness of parents to randomize their children with a UCC to either IOL implantation or CL correction. RESULTS: In 1997, 89% of the 260 respondents reported that in the previous year they had treated at least one infant with a UCC, but only 4% had implanted an IOL in an infant <7 months old. Silsoft (Bausch & Lomb, Rochester, NY) CL correction was the preferred treatment choice for 84% of the respondents. In 2001, 21% of the 279 respondents had implanted an IOL in an infant. On a scale from 1 to 10 with 1 strongly favoring an IOL implant and 10 strongly favoring a CL, the median score was 7.5. Sixty-one percent of the respondents indicated that they would be willing to randomize children with a UCC to one of these two treatments. The main concerns about IOL implantation were poor predictability of power changes, postoperative complications, inflammation, and technical difficulty of surgery. The main concerns about CL correction were poor compliance, high lens loss rate, high cost, and keratitis. In our pilot study, 30 infants <7 months of age were evaluated at nine clinical centers for a visually significant UCC. Of 24 infants eligible for randomization, the parents of 17 (71%) agreed to randomization. CONCLUSIONS: Although most AAPOS members still favor CL correction after cataract surgery for a UCC, five times as many had implanted an IOL in an infant in 2001 compared with the number in 1997. Parents were almost equally divided in their preference for IOL implant versus CL correction. Given the relative equipoise of AAPOS members regarding these treatments and the willingness of more than two thirds of parents to agree to randomization, it seems likely that a randomized clinical trial comparing these two treatments could indeed be conducted.