Ultrasound biomicroscopy (UBM) characteristics of scleral tunnels created with suture needles commonly used during strabismus surgery.

PURPOSE: To enhance the safety and efficacy of surgical treatment of strabismus, we sought to measure and determine the ultrasound biomicroscopy (UBM) profile of scleral tunnels created with needles commonly used during strabismus surgery, to determine which needles are less likely to create the complication of scleral perforation. METHODS: Adult cadaver eyes were secured in a styrofoam head. Intraocular pressure was maintained between 15 and 21 mm Hg. Then S14, S24, S28 and TG100 needles were used to create scleral tunnels simulating those created during routine strabismus surgery. Ten scleral tunnels were created with each needle type at 3 different sites on the globe, for a total of 120 passes. The thickness of the sclera and the maximum depth and length of each scleral tunnel were measured using UBM. RESULTS: The mean tunnel depth below the scleral surface (+/- SD) was 0.43 +/-0.11 mm, 0.37 +/-0.09, 0.40 +/-0.08 and 0.34 +/-0.07 mm, for the S14, S24, S28 and TG100 needles, respectively (P=0.002, One way ANOVA). For both the S14 and S28 needles, there was a "statistically significant" P 0.05) linear trend of an increase in the depth of the pass as the length of the pass increased (P=0.01 for the S14 and P=0.02 for the S28 {Pearson Correlation 2 tailed test}). A similar trend was found with the S24 needle but the trend was not "statistically significant" (P=0.35). No such trend was found with the TG100 needle. CONCLUSIONS: Needle design had a definite impact on the characteristics of scleral tunnels created to simulate those made during strabismus surgery and may influence needle selection by the surgeon for different or various surgical circumstances, but the differences were not such as to predicate for or against the general use of any of these four needles for strabismus surgery.

Pulsed mode versus near-continuous mode delivery of diode laser photocoagulation for high-risk retinopathy of prematurity.

OBJECTIVE: To compare structural and functional outcomes and efficiency of diode laser photocoagulation for retinopathy of prematurity (ROP) when delivered in a pulsed mode versus a near-continuous mode. METHODS: A retrospective study was conducted of 138 patients who underwent diode laser photocoagulation for threshold ROP using either pulsed or near-continuous delivery. Laser-related complications and structural and functional outcomes were analyzed. Prospectively, time efficiency and total energy used were evaluated in nine infants with bilateral symmetric high-risk prethreshold ROP in which one eye of each infant was randomized to pulsed and the fellow eye to near-continuous delivery. RESULTS: There was no significant difference between groups with regards to prevalence of posterior disease (Zone 1 or posterior Zone 2) (p = 0.11), postoperative vitreous haze (p = 0.60), postoperative complications (p = 0.38), retinal detachment (p = 0.90), strabismus (p = 0.73), amblyopia (p = 0.69), or refractive error (p = 0.95). Mean time for treatment was 23 minutes using pulsed delivery versus 14 minutes per eye with near-continuous delivery (p < 0.001). The mean total power used per eye with pulsed mode delivery was 1.5 x 10(5) W versus 1.1 x 10(5) W with near-continuous delivery (p = 0.015). CONCLUSIONS: No differences in complications, functional outcome, or structural outcome were found between using pulsed mode and near-continuous mode diode laser delivery for high-risk ROP. Near-continuous laser delivery, in our hands, was more time-efficient and used less total power.

Long-term outcomes of photorefractive keratectomy for anisometropic amblyopia in children.

PURPOSE: To evaluate the long-term visual acuity (VA) and refractive error responses to excimer laser photorefractive keratectomy (PRK) for treatment of anisometropic amblyopia in children. DESIGN: Prospective interventional case-control study. PARTICIPANTS: Eleven children, 2 to 11 years old, with anisometropic amblyopia who were noncompliant with conventional therapy with glasses or contact lenses and occlusion therapy were treated with PRK. A cohort derived retrospectively of 13 compliant and 10 noncompliant children with refractive errors similar to those of the PRK group who were treated with traditional anisometropic amblyopia therapy served as control groups. INTERVENTION: Photorefractive keratectomy for the eye with the higher refractive error. MAIN OUTCOME MEASURES: (1) Refractive error reduction and stability in the treated eye, (2) cycloplegic refraction, (3) VA, (4) stereoacuity, and (5) corneal haze up to 3 years after PRK. Compliant and noncompliant children with anisometropia amblyopia were analyzed as controls for refractive error and VA. RESULTS: Preoperative refractive errors were -13.70 diopters (D) (+/-3.77) for the myopic group and +4.75 D (+/-0.50) for the hyperopic group. Mean postoperative refractive errors at last follow-up (mean, 31 months) were -3.55 D (+/-2.2.5) and +1.41 D (+/-1.07) for the myopic and hyperopic groups, respectively. At last follow-up, cycloplegic refractions in 4 (50%) of 8 myopes and all hyperopes (100%) were within 3 D of that of the fellow eye. Five (63%) of 8 myopic children achieved a refraction within 2 D of the target refraction. Two (67%) of 3 hyperopic patients maintained their refractions within 2 D of the target. Refractive regressions (from 1 year after surgery to last follow-up) were 0.50+/-1.41 D (myopes) and 0.60+/-0.57 D (hyperopes). Seven children (77%) were able to perform psychophysical VA testing preoperatively and postoperatively. Five (71%) of the 7 children had uncorrected VA improvement of at least 2 lines, and 4 (57%) of 7 had best spectacle-corrected VA improvement of at least 2 lines, with 1 improving 7 lines. Five (55%) of 9 children had improvement of their stereoacuity at last follow-up. Subepithelial corneal haze remained negligible. The mean final VA of the PRK group was significantly better than that of the noncompliant control group (P = 0.003). The mean final refractive error for both myopic and hyperopic groups was also significantly better that that of the control groups (P = 0.007 and P<0.0001, respectively). CONCLUSIONS: Photorefractive keratectomy for severe anisometropic amblyopia in children resulted in long-term stable reduction in refractive error and improvement in VA and stereopsis, with negligible persistent corneal haze.

Involution of retinopathy of prematurity after laser treatment: factors associated with development of retinal detachment.

PURPOSE: To identify specific features during the process of involution of retinopathy of prematurity after treatment at threshold that are associated with development of a retinal detachment. DESIGN: Retrospective case series. METHODS: The evolution of retinal detachments over time was analyzed retrospectively in 262 treated eyes of 138 infants. Specific features hypothesized to be associated with development of a retinal detachment were analyzed, including vitreous organization defined as clinically important, active stage 3 disease and active plus disease more than 21 days after treatment, and vitreous hemorrhage defined as clinically important. RESULTS: A retinal detachment developed in 36 (13.7%) of 262 eyes. Vitreous organization meeting our clinically important definition was associated with a 31-fold (confidence interval [CI] 5.37-183.63; P < .0001) and 13-fold (CI 2.97-58.59; P < .0001) increase in the odds for retinal detachment for right and left eyes, respectively. Vitreous hemorrhage defined as clinically important was associated with a 38-fold (CI 2.69-551.19; P = .007) and 15-fold (CI 1.65-144.12; P = .02) increase in the odds for retinal detachment for right and left eyes, respectively. The timing of retinal detachment relative to vitreous hemorrhage was not determined. Prolonged activity of Stage 3 disease or plus disease more than 21 days after treatment was not associated with development of a retinal detachment. CONCLUSIONS: Clinically important vitreous organization and vitreous hemorrhage were predictive for development of a retinal detachment. Evaluation of preemptive reintervention strategies for eyes at highest risk for developing a retinal detachment may be reasonable.

Corneal thickness in children.

OBJECTIVE: To determine normal central and paracentral corneal thickness measurements in the pediatric population and to determine if these measurements are consistent across different pediatric age groups and different racial groups. DESIGN: Prospective observational case series. METHODS: Pachymetry measurements were performed on 198 eyes of 108 children. The measurements were taken centrally as well as at four paracentral sites 3 mm from the corneal center at the 3, 6, 9, and 12 o'clock positions. The two-tailed t test was used for comparison of the continuous means for values of corneal thickness. Analysis of variance (ANOVA) was performed to determine differences among age and ethnic groups RESULTS: The mean central corneal thickness (CCT) was 549 +/- 46 microm. Paracentral corneal thickness mean values, as measured 3 mm from the corneal center, were as follows: superior, 575 +/- 52 microm; nasal, 568 +/- 50 microm; inferior, 568 +/- 51 microm; and temporal, 574 +/- 47 microm. The mean CCT values were significantly thinner than at each of the mean paracentral points (P < .05 for each comparison, paired t test). Paracentral corneal thickness measurements demonstrated no significant differences between locations (P > .05, variance analysis). The mean CCT +/- SD for each age group was as follows: 6 to 23 months, 538 +/- 40 microm; 2 to 4 years, 546 +/- 41 microm; 5 to 9 years, 566 +/- 48 microm; and 10 to 18 years, 554 +/- 35 microm (ANOVA P = .012). ANOVA performed on central pachymetry values demonstrated no significant differences among racial subgroups. CONCLUSIONS: Pediatric central and paracentral corneal thicknesses increase slowly over time and reach adult thicknesses at 5 to 9 years of age.

Risk factors for treatment failure of anisometropic amblyopia.

PURPOSE: This study sought to explore factors which might predict the lack of vision improvement following therapy of anisometropic amblyopia. METHODS: We retrospectively reviewed the records of 104 children aged 3 to 8 years who had anisometropic amblyopia with a difference in the refractive power between the two eyes of at least 1 diopter, a difference in corrected visual acuity between the two eyes of at least 3 logMAR units, visual acuity in the amblyopic eye of 20/50 or worse, and no ocular structural abnormalities. Patients were treated with either patching or atropine penalization therapy. Patients with strabismus were included. Treatment failure was defined in two ways: (1) functional failure indicating a final visual acuity in the amblyopic eye worse than 20/40 and (2) relative failure indicating less than three lines of logMAR visual acuity improvement regardless of final vision. RESULTS: Failure risk factors were as follows: age above 6 at the onset of treatment (adjusted odds ratio [OR] (95% confidence limits [CL] = 4.69 [1.55, 14.2]), the presence astigmatism of more than 1.50 diopters in the amblyopic eye (adjusted [OR] (95% CL) = 5.78 [1.27, 26.5]), poor compliance with treatment (adjusted [OR] (95% CL) = 5.47 [1.70, 17.6]), and initial visual acuity in the amblyopic eye of 20/200 or worse (adjusted [OR] (95% CL) = 3.79 [1.28, 11.2]). Strabismus was not found to be a significant risk factor. Neither the type or amount of refractive error nor the difference in the refractive power between the two eyes was a significant risk factor for treatment failure. CONCLUSION: Eyes with poor initial visual acuity, the presence of significant astigmatism, and age over 6 years were less likely to achieve successful outcome. The clinical profile of patients with anisometropic amblyopia may be useful in predicting response to therapy, but compliance with treatment has a major effect on response to therapy.

Parent-administered visual acuity testing: is it reliable and can it improve office efficiency?

PURPOSE: To evaluate the accuracy of a parent-administered visual acuity test, using the electronic visual acuity tester (EVA) (JAEB Center, Tampa, FL) and evaluate its use as a means to improve efficiency of office acuity testing. METHODS: This was a prospective experimental study. Part I: Sixty-four children had their visual acuity determined using the EVA, first by their parents and then by an ophthalmic technician. Acuity scores were compared. Part II: Forty-four other children were randomly assigned to one of 2 groups. Group A (parent-prescreen) children had their visual acuity determined first by the parents using the EVA. The visual acuity result in that child was then rechecked by the technician using the Reinforcement Phase and Phase 2 of the Amblyopia Treatment Study (ATS) visual acuity testing protocol. Group B (full ATS protocol) children had their acuity determined by the technician using the full ATS protocol. The number of optotypes presented by the technician in order to determine the acuity in each group was compared. RESULTS: Part I: Reliability of parent-determined visual acuity scores was high (r = 0.91 and 0.81 for right eyes (OD) and left eyes (OS), respectively), with 93% of right eye parent scores and 85% of left eye parent scores within 0.11 logarithm of minimal angle of resolution (logMAR) units (ie, within one line of vision) of the technician score. Part II: The parent prescreen group (Group A) required presentation of 66% fewer optotypes to the OD and 68% fewer optotypes to the OS than the full ATS protocol group (Group B) (OD: P = 5.4 x 10(-18); OS: P = 6.5 x 10(-18)). CONCLUSIONS: Visual acuity testing results by parents using the EVA are reliable. Electronic visual acuity prescreening by parents reduces the number of optotype presentations required to be shown by the technician to accurately determine acuity. Use of a parent-assisted screening system in the waiting room may translate to increased office efficiency.

Photorefractive keratectomy for pediatric anisometropia: safety and impact on refractive error, visual acuity, and stereopsis.

PURPOSE: To establish the safety and possible efficacy of excimer laser photorefractive keratectomy (PRK) for treatment of pediatric anisometropia. DESIGN: Interventional case series METHODS: This is a prospective, noncomparative interventional case series at an individual university practice of photorefractive keratectomy in 11 children aged 2 and 11 years with anisometropic amblyopia who were unable or unwilling to use contact lens, glasses, and occlusion therapy to treat the amblyopia. The eye with the higher refractive error was treated with PRK using a standard adult nomogram. The refractive treatment goal was to decrease the anisometropia to 3 diopters or less. Main outcome measures were cycloplegic refraction, refractive correction, degree of corneal haze, uncorrected and best spectacle-corrected visual acuity, and stereopsis over 12 months. RESULTS: All patients tolerated the procedure well. The mean refractive target reduction was -10.10 +/- 1.39 diopters for myopia and +4.75 +/- 0.50 diopters for hyperopia. The mean achieved refractive error reduction at 12 months for myopia was -10.56 +/- 3.00 diopters and for hyperopia was +4.08 +/- 0.8 diopters. Corneal haze at 12 months was minimal. Uncorrected visual acuity improved by 2 or more lines in 6 (75%) of the eight children able to perform psychophysical acuity tests. Best spectacle-corrected visual acuity improved by 2 lines in 3 (38%) of patients. Stereopsis improved in 3 (33%) of nine patients. CONCLUSIONS: Pediatric PRK can be safely performed for anisometropia. The refractive error response in children appears to be similar to that of adults with comparable refractive errors. Visual acuity and stereopsis improved despite several children being outside the standard age of visual plasticity. Photorefractive keratectomy may play a role in the management of anisometropia in selected pediatric patients.

The effect of off-the-visual-axis retinoscopy on objective refractive measurement.

PURPOSE: To determine the effect of off-axis retinoscopy on objective refractive measurement. DESIGN: Prospective experimental study. METHODS: Eight volunteers underwent cycloplegic retinoscopy of their right eye on-the-visual-axis, and 5, 10, 15, and 20 degrees off-the-visual-axis in adduction. A single masked examiner performed all retinoscopy with random order of the patient and axis refracted. RESULTS: The average spherical retinoscopic value at 0, 5,10,15, and 20 degrees of off-axis alignment was -0.40, -0.90, -1.00, -1.38, and -1.80 diopters, respectively. The average spherical equivalent retinoscopic value obtained for each of the above positions of eye alignment was -0.02, -0.59, -0.45, -0.64, and -0.98 diopters, respectively. The induced cylinder power increased by an average of 3% for each degree of off-axis retinoscopy, though the axis of the cylinder was not predictable. CONCLUSION: Objective refractive measurement by retinoscopy is significantly altered by off-the visual-axis retinoscopy. The induced error may be clinically important even with small degrees of eccentricity.

Use of the RetCam 120 for fundus evaluation in uncooperative children.

PURPOSE: To report our experience using the RetCam 120 to evaluate suspected retinal pathology in children who did not cooperate for standard in-office examination. DESIGN: Interventional case series. METHODS: We reviewed charts of eight consecutive uncooperative children with suspected fundus abnormalities that were photographed using the RetCam 120 as a routine part of patient care. RESULTS: Three uncooperative children with suspected pathology required RetCam 120 photos because of inadequate fundus examination. Five had pathology or suspected pathology that required more detailed examination. In all of these children, we were able to reach or rule out a diagnosis. CONCLUSION: The Retcam 120 digital fundus camera has utility as an in-office diagnostic tool for fundus examination of poorly cooperative children and may be a good alternative to examination under anesthesia or sedation in selected cases.