Sound Eye Research Articles

Monocular Oral Reading Performance After Amblyopia Treatment in Children

To evaluate the monocular oral reading rate, accuracy, fluency, and comprehension in 10-year-old children previously treated for amblyopia. Prospective, observational case series. Seventy-nine children (mean age, 10.3 years) previously treated in a multicenter randomized trial comparing patching and atropine were tested at seven sites using a modification of the Gray Oral Reading Test, Fourth Edition (GORT-4). The mean visual acuities (VA) in the amblyopic and fellow eyes at the time of the reading assessment were 0.17 logarithm of the minimum angle of resolution (logMAR) units (approximately 20/32) and -0.03 logMAR units (approximately 20/20), respectively. Compared with the sound eye, amblyopic eye performance was worse when reading orally with respect to rate (P < .001), accuracy (P = .03), and fluency (P < .001). Reading comprehension scores were similar with the amblyopic and fellow eyes (P = .45). Similar results were found with respect to original treatment group assignment (atropine or patching). There was a modest correlation between interocular difference (IOD) of VA at age 10 years and IOD in reading rate (r = 0.37; 95% confidence interval [CI], 0.18 to 0.56) and fluency (r = 0.28; 95% CI, 0.08 to 0.49). There was no correlation between the IOD in VA and IOD in accuracy (r = 0.08; 95% CI, -0.14 to 0.30) or comprehension (r = 0.16; 95% CI, -0.05 to 0.37). The monocular oral reading ability when measured with the GORT-4 was slightly worse when reading with previously treated amblyopic eyes compared with fellow eyes in terms of rate, accuracy, and fluency, but reading comprehension testing was similar.

Binocular coordination of saccades in Duane Retraction Syndrome

Disconjugate oculomotor adaptation is driven by the need to maintain binocular vision. Since binocular vision in Duane Retraction Syndrome (DRS) patients is normal in half of their horizontal field of gaze (i.e., sound-side of gaze), we wondered whether oculomotor adaptive capabilities are efficient despite such a severe impairment of eye motility towards the other half of the horizontal field of gaze (i.e., affected-side gaze). We compared properties of horizontal saccades of patients with congenital unilateral Duane Retraction Syndrome type I in binocular viewing and monocular viewing conditions by simultaneously recording both eyes with the search coil technique. Our results show a mismatch between the pulse and the step signal of the innervation for saccades. When tested in the affected eye viewing condition (sound eye covered), the eyes showed not only similarly-directed increases of the saccadic gain (pulse signal) in the two eyes but also disjunctive post-saccadic drifts (step signal). This behavior suggests that visuomotor errors presented only to the affected eye were transferred to the sound eye, producing conjugate changes of the saccadic command. The post-saccadic command remained unchanged, however, and controlled the final position of each eye separately. This suggests that monocular adaptation is possible only for the step of innervation (i.e., controlling the final eye position) but not for the pulse of innervation (i.e., controlling the saccadic gain), even though the peculiarity of unilateral DRS type I offers a clear advantage for separate pathways of control for the two eyes.

Comparison of the visual effects of Fresnel prisms in normal and amblyopic eyes

To assess the effects of Fresnel prisms on visual acuity and peak contrast sensitivity in the amblyopic and sound eyes of participants with amblyopia and to determine whether these functions were affected by Fresnel prisms to a different degree than those of controls. The LogMAR visual acuity and peak contrast sensitivity of 10 unilateral amblyopic participants (mean age, 22.6 years) and 9 controls (mean age, 26.2 years) were tested with Fresnel prisms of powers 5(Delta), 10(Delta), 15(Delta), 20(Delta), and 25(Delta) and without a Fresnel prism. A statistically significant reduction in visual acuity with increasing prism power was found for all 3 groups, with the visual acuity of the amblyopic eyes being the least affected by the prisms. No statistically significant differences were found between the control and the sound eyes. No statistically significant differences in the effects of the prisms on peak contrast sensitivity could be detected between the 3 groups. Fresnel prisms were found to have a smaller effect on those amblyopic eyes with a poorer baseline visual acuity, indicating that these eyes may tolerate strong prisms without substantially impairing their visual acuity. Fresnel prisms have a lesser effect on the visual acuity of amblyopic eyes than on controls. In contrast, results for peak contrast sensitivity were very similar for each of the groups tested, and no significant differences were evident between the amblyopic, sound, and control eyes.

The Prospective Comparison of the Efficacy of Intermittent Atropine Penalization and Part-time Occlusion Therapy

Purpose: The objective of this study was to compare prospectively the efficacy between intermittent atropine penalization and part-time occlusion therapy for amblyopia in patients younger than 10 years old. Methods: The patients with newly diagnosed amblyopia were randomly assigned to either atropine penalization (Group A) or occlusion therapy (Group O). One drop of atropine was instilled into the sound eyes of patients in group A twice per week, while each patient in group O underwent daily patching for 6 hours in their sound eyes. The minimum follow-up time was 3 months after treatment. Best corrected visual acuity and compliance were compared for both groups. Results: A total of 43 patients were enrolled in this study, with 18 assigned to group A and 25 to group O. The follow-up period was not significantly different between group A and group O (6.3 and 7.0 months, respectively; p=0.437). The final corrected visual acuity (LogMAR) scores of amblyopic eyes in both groups showed significant improvement in the visual acuity of amblyopic eyes compared with that at baseline (0.28 in group A and 0.19 in group O). Group A had a higher level of compliance than group O (97.0 and 91.5%, respectively; p=0.007). There was no difference in the groups with regard to visual acuity in amblyopic eyes, which showed similar improvement (3.5:3.4 lines, respectively; p=0.867). Conclusions: This study shows that for treating amblyopia in children younger than 10 years old, intermittent atropine penalization seems to be as effective as part-time occlusion. J Korean Ophthalmol Soc 49(6):958-966, 2008

Laser in situ Keratomileusis for Spherical Hyperopia and Hyperopic Astigmatism Using the NIDEK EC-5000 Excimer Laser

To assess the efficacy, predictability, and safety of LASIK for the surgical correction of low to moderate hyperopia and hyperopic astigmatism using the NIDEK EC-5000 excimer laser. In a multicenter United States Food and Drug Administration (FDA) regulated study of LASIK, 7 centers enrolled 293 eyes with manifest refraction sphere that ranged from +0.50 to +6.00 diopters (D) with or without astigmatism up to 3.00 D. The intended outcome was plano in all eyes. Patients were treated bilaterally. One year postoperative outcomes are reported. The mean spherical equivalent refraction (MRSE) for all eyes changed from +3.51 +/- 1.45 [corrected] D (range: +0.50 to +6.63 D) preoperatively to +0.35 +/- 0.54 D (range: +1.63 [corrected] to +2.00 D) 1 year [corrected] Overall, 61% (170/279) of eyes achieved distance uncorrected visual acuity (UCVA) of 20/20 or better, 82% (228/279) of eyes saw 20/25 or better, and 99% (277/279) of eyes saw 20/40 or better. Refractive accuracy was demonstrated as 63.1% (176/279) of eyes achieved a MRSE within +/- 0.50 D and 90.3% (252/279) of eyes within +/- 1.00 D. Less than 2% (4/279) of eyes lost 2 lines of distance best spectacle-corrected visual acuity. Stability of refraction was demonstrated by 6 months, with a mean hyperopic shift of < 0.03 D from 3 to 6 months. The NIDEK EC-5000 corrected hyperopia and hyperopic astigmatism with UCVA, refractive accuracy, 1-year stability, and safety that surpassed all FDA criteria.

Prescription and management of contact lenses in patients with monocular visual impairment

Purpose Contact lens correction for refractive error in patients with monocular visual impairment may be desirable. However, the potential for damage to the sound eye must always be considered in such patients. This report outlines the prescription and management of contact lens wear in a monocular patient. The case report is followed by a discussion of the risks of vision loss associated with contact lens wear. Case report The author conducted a clinical interview, refraction, ocular examination, and contact lens evaluation of a 38-year-old female patient who had undergone a lensectomy in her right eye and the enucleation of her left eye. The patient presented wearing a conventional aphakic hydrogel contact lens in her right eye. She routinely wore her contact lens for up to 16 hours daily and occasionally slept while wearing it. Best-corrected spectacle acuity was 20/40-2 with +13.75 diopter sphere in her right eye. Clinical examination showed 3 to 4 mm of well-perfused neovascularization with associated pannus in the superior quadrant of her cornea and 1 to 2 mm of peripheral neovascularization in the remainder of the cornea. She was refit with a 2-week replacement hydrogel contact lens that partially corrected her refractive error, and she was encouraged to wear polycarbonate spectacles full time for the remainder of her refractive correction and for protection of the right eye. Conclusions Monocularly impaired patients who choose to wear contact lenses for the correction of refractive error should be aware of the risk of potentially sight-threatening contact lens complications. The importance of meticulous hygiene and appropriate contact lens wearing schedules should be emphasized with monocular patients. They should also be encouraged to wear the appropriate spectacle correction to reduce the risk of injury to their sound eyes.

The effect on refractive error of unilateral atropine as compared with patching for the treatment of amblyopia

Our objective was to determine whether the use of unilateral atropine as amblyopia therapy leads to an asymmetric change in refractive error compared with patching. Patients were enrolled in a clinical trial in which atropine 1% solution or occlusion with an adhesive patch was administered daily to the sound eye of children 3 to less than 7 years of age for a period of at least 6 months to a maximum of 2 years. Refractive error at entry and at 2 years was determined with cycloplegic retinoscopy for 282 of 419 patients enrolled. The baseline mean refractive error was + 3.13 diopters (D) in patients assigned randomly to receive atropine and + 2.58 D in patients assigned randomly to wear the patch. The mean change in refractive error of the sound eye was + 0.10 D in the atropine group (N = 134) and + 0.08 D in the patch group (N = 148). Patients also were subdivided into those treated with atropine only (n = 41) and patching only (n = 64) because some children changed treatments during their study participation. The mean change for the sound eyes was -0.21 D for the patients receiving only atropine and -0.06 D for the patients receiving only patching. Unilateral atropine applied to the sound eye compared with occlusion was not associated with any adverse effect on refractive error following up to 2 years of treatment.

Monocular activation of V1 and V2 in amblyopic adults measured with functional magnetic resonance imaging

Although previous neuroimaging efforts clearly indicate visual cortical dysfunction in adults with amblyopia, the extent of abnormalities remains unclear. This functional magnetic resonance imaging (fMRI) study directly compared activity in visual cortex produced by monocular stimulation in 18 adults (six esotropic strabismics, six anisometropes, and six controls). Measures were made in three cortical regions-of-interest, individually defined using standard retinotopic mapping techniques in the nonamblyopic eye, corresponding to extrafoveal V1, extrafoveal V2, and the foveal representation at the occipital pole. Fixation stability was monitored and found not to differ significantly between subject groups. Overall results showed depressed fMRI signal magnitude for amblyopic eyes compared with sound eyes, although a few subjects did not show this trend. Assessment of the spatial extent of activation using an ocular dominance index did show significantly larger interocular differences for both strabismics and anisometropes compared with control subjects for whom eye dominance was carefully defined. In addition, both amblyopic groups showed less cortical area able to be significantly driven by either eye. The magnitude of these effects was equivalent in V1, V2, and the foveal representation, as well as between amblyopic groups. No difference was detected in the strength of signal from the nasal versus temporal retina in either amblyopic group. Asymmetries in magnitude of monocular activation do occur in subjects with amblyopia, but these basic measures are limited in terms of sensitivity for mild to moderate amblyopia and for specificity between subtypes.

Association Between Fixation Preference Testing and Strabismic Pseudoamblyopia

Fixation preference testing is the mainstay of clinical diagnosis of strabismic amblyopia in preverbal children and infants. The purpose of this study is to evaluate the strength of the association between fixation preference and strabismic amblyopia. Eighty patients (3 to 8.3 years) with manifest strabismus and the capability to cooperate with a Snellen acuity test were prospectively examined. Thirty patients were diagnosed as having partially accommodative esotropia, 15 as having congenital esotropia, 15 as having primary acquired esotropia, 15 as having congenital exotropia, and 5 as having hypertropia. Visual acuity levels were measured using a Snellen E-chart. Fixation preference was evaluated and graded from 0 (free alternation) to 3 (strong uniocular fixation). At the end, we compared visual acuity and the grade of fixation preference. Amblyopia was defined as a difference of two or more Snellen lines between the two eyes. Sixty patients (75%) had strong uniocular fixation (grade 3). Of these patients, 50 (85%) had no amblyopia and only 10 had deep amblyopia. Ten patients (12.5%) had moderate fixation (grades 1 and 2). Of these patients, five (50%) had no amblyopia and five had moderate amblyopia. Ten patients (12.5%) had free alternation (grade 0). These patients had equal vision. Treatment of strabismic amblyopia on the basis that the sound eye will show strong fixation preference can be hazardous. Fixation preference could be a severe form of eye dominance, and better methods for testing visual acuity in preverbal children are required.

Clinical Effects of Conjunctiva-Müller Muscle Resection in Anophthalmic Ptosis

PurposeTo evaluate the clinical effects of conjunctiva-Müller muscle resection through conjunctival incision in anophthalmic patients with mild ptosis.MethodsConjunctiva-Müller muscle resection was performed by one surgeon in 8 patients (8 eyes) who had received evisceration or enucleation and responded to 10% phenylephrine solution to correct ptosis. The average age of the patients was 35.87±13.4 years. Ptosis was seen from 1 to 34 months after evisceration or enucleation. The preoperative MRD 1 was -2 to 0.5 mm (average : -0.25±1.10 mm) and the difference of MRD 1 between before and after 10% phenylephrine use was 2.56±0.98 mm. The Müller muscle was resected 7.5 to 9 mm through conjunctival incision during surgery to match the MRD 1 of sound eye. Mean follow-up period after the operation was 2 to 16 months (average : 8.1 months).ResultsPostoperatively, the MRD 1 increased by 1.81±0.88 mm on the average, corresponding to the improvement in lid elevation after the use of 10% phenylephrine performed before resection. Surgery was successful in most patients, and postoperative difference in MRD 1 was less than 1 mm from the sound eye. No special postoperative complication was observed.ConclusionsConjunctiva-Müller muscle resection is one of the effective methods of correcting mild ptosis in anophthalmic patients.

Ocular Torsion in Unilateral Superior Oblique Palsy

Purpose: We evaluated the concordance of laterality of the paretic eye and the torsional eye in unilateral superior oblique palsy showing an inferior oblique overaction. Methods: Thirty-nine patients diagnosed as having a unilateral superior oblique palsy were evaluated for visual acuity, refractive manifestation, ocular movement, prism cover test, and fundus photograph. Of these patients, 32 derived from congenital causes and 7 acquired the condition from trauma. An ocular movement exam was performed to check an inferior oblique overaction, and a fundus photograph was used to measure the ocular torsional amount. Inferior oblique myectomy or recession was performed along with horizontal strabismus surgery. Results: Objective extorsion was presented in paretic eyes of 29 patients (74.4%) and nonparetic eyes of 10 patients (25.6%). The congenital superior oblique palsy patients were divided into two groups by the concordance of laterality of paretic eyes and torsional eyes. In the concordance group of 22 patients, the torsional amount was decreased from +17.69°to +7.98°and inferior oblique overaction from +2.27°to +0.25°after an inferior oblique muscle weakening procedure. In the discordance group of 10 patients, torsional amount was decreased from +16.97°to +8.73°and inferior oblique overaction from +2.50°to +0.21°postoperatively. In acquired oblique palsy patients, all patients showed the concordance of laterality, and the torsional amount was decreased from +16.76°to +8.80°and inferior oblique overaction from +2.5°to +0.21°after inferior oblique weakening procedure. Conclusions: We found that the paretic eye and the torsional eye may not coincide in congenital superior oblique palsy but always coincide in acquired oblique palsy after trauma. After an inferior oblique muscle weakening procedure, ocular torsional amount of paretic or sound eye is decreased in every case.

Continuous Full-Time Occlusion of the Sound Eye Vs Full-Time Occlusion of the Sound Eye Periodically Alternating with Occlusion of the Amblyopic Eye in Treatment of Amblyopia: A Prospective Randomized Study

To compare continuous full-time (24 hours per day) occlusion of the sound eye with full-time occlusion (24 hours per day) of the sound eye 1 day more than the years of age periodically alternating with occlusion of the amblyopic eye for 1 day, as treatments for profound strabismic amblyopia in children older than 5 years. A total of 53 patients with visual acuity (VA) of 0.4 and less in the amblyopic eye (tested by crowded Landolt Cs) after previously being provided optimal optical correction were randomly assigned to receive either of the two patching regimens. VA and pattern reversal visual evoked potentials (PVEP) were recorded prospectively at 1-month intervals. Improvement in VA and the reduction in crowding difficulties (CD) were the main outcome measures of the treatment efficiency. Both treatment modalities were equally effective. Of the 51 subjects who completed the study, 21 (41.2%) were cured whereas 32 (62.7%) attained satisfactory improvement. Recovery of VA was related to age, with cure being obtained in 23.5% (4/17) and satisfactory improvement in 52.9% (9/17) of patients older than 9 years. Larger gain in VA influenced the stability of the vision over time. It can be concluded that in clinically monitored parameters both treatment modalities were equally effective without any statistical or clinical significance in the observed groups of patients. However, events like the ""trade-off"" effect, occurrence of occlusion amblyopia, or prolongation of PVEP latency of the sound eye indicate that full-time continuous occlusion possibly presents a more effective form of treatment.

Effects of Unilateral Ocular Motor Nerve Palsies on Smooth Pursuit Eye Movements in Adult Patients

Aim: The aim of this study was to investigate the influence of single ocular muscle weakness on smooth pursuit eye movements. Methods: Infrared video recordings of horizontal and vertical eye movements were obtained from 14 adult patients with either unilateral abducens nerve palsy or trochlear nerve palsy. During the recordings, subsequent series of horizontal, vertical and oblique ramp stimuli of 10°/s constant target velocity and ±10° amplitude were presented under monocular viewing conditions. Results: In both forms of ocular nerve palsies, similar changes of pursuit eye movements were observed in the pulling plane of the paretic muscles. The movements of the covered paretic eye showed the lowest amplitude and gain values as well as the lowest numbers of catch-up saccades. The highest amplitude and gain values were calculated from the movements of the covered sound eye. The highest numbers of saccades, however, were produced by the fixating paretic eye. Conclusions: We conclude that the fixating paretic eye compensates for the paresis by raising the pursuit gain and the number of catch-up saccades. In the covered paretic eye, however, monocular adaptation is connected with a symmetric low pursuit gain and a reduced number of saccades in the pulling plane of the paretic muscle.

Selective fovea-related deprived activation in retinotopic and high-order visual cortex of human amblyopes

Amblyopia is a visual disorder starting at early childhood and characterized by reduced visual acuity not of optical origin or due to any eye disease. One expression of such an anomalous early visual experience is abnormal foveal vision. In a previous fMRI study, faces that were presented to amblyopic eyes evoked little response compared to houses in high-order visual areas. Patients also demonstrated reduced recognition of facial expression, raising the possibility that these face-selective abnormalities are related to foveal vision deficit. Whether this deficit originates in low-level processing or is mediated by compromised activation in high-order visual areas is unresolved. In the present functional magnetic resonance imaging (fMRI) study, we explored the impact of amblyopia on the representation of object images presented in foveally biased central versus peripheral retinotopic eccentricities through manipulation of object size. Small and large pictures were correlated to visual acuities of 6/6 and 6/60, respectively. In low-level visual areas, the amblyopic eye showed significantly reduced activation for centrally placed, small pictures than the sound eye, while activation to large pictures was only slightly reduced. Similarly, in high-order visual areas, the amblyopic eye showed marked reduction in activation in the fusiform gyrus, with normal activation in the collateral sulcus. The center/periphery size-related amblyopic outcomes of this study support a “bottom–up” nature of the center–periphery effect observed in high-order visual areas. Taken together, these findings point to the regional extent and functional selectivity of fovea-related cortical reorganization that is related to abnormal visual development of one eye.

Retinal Nerve Fiber Layer Thickness in Amblyopic Eyes

To compare the peripapillary retinal nerve fiber layer (RNFL) thickness of sound and amblyopic eyes. Prospective observational case series. Institutional. Patients with unilateral strabismic, anisometropic, or combined amblyopia. Fast RNFL analysis with ocular coherence tomography (OCT) of sound and amblyopic eyes. Mean RNFL thickness. For the 17 patients (mean age 10.7 years) in whom both eyes were imaged, the mean thickness of the sound eye was 109.2 microm (median 112.7) and of the amblyopic eye was 104.2 microm (median 105.0), and the average difference (sound eye less amblyopic eye) was 5.0 microm (median 3.0) (95% confidence interval -2.3, 12.2, P = .17). The sound eye was 10 microm or more thicker than the amblyopic eye in four patients; the amblyopic eye was 10 microm or more thicker than the sound eye in one patient; and the difference was within 10 microm in 12 patients. Test-retest data were obtained for 23 pairs of sound eyes and 21 pairs of amblyopic eyes, with 75% of the test-retest pairs within 7%. We found a small, but not clinically significant, difference in nerve fiber layer (NFL) thickness between amblyopic and sound eyes. Reliability was excellent, with most eyes testing within 7% of the first test.

Posterior Canal Dehiscence Syndrome Caused by an Apex Cholesteatoma

To compare audio-vestibular findings caused by a dehiscence of the posterior semicircular canal with those found in the superior canal dehiscence syndrome. Case report. University hospital, tertiary referral center. The 44-year-old woman suffered from a gradual hearing loss with pulse-synchronous tinnitus as well as sound and pressure-induced vertigo. Audio-vestibular testing and high-resolution computed tomography. The superior canal dehiscence syndrome is caused by failure of normal postnatal bone development in the middle cranial fossa leading to absence of bone at the most superior part of the superior semicircular canal. The typical features for this syndrome are sound- and pressure-induced vertigo with torsional eye movements, pulse synchronous tinnitus and apparent conductive hearing loss in spite of normal middle-ear function. We present a patient with very similar symptoms and findings who, instead, had a posterior semicircular canal dehiscence caused by an apex cholesteatoma. Patients with semicircular canal dehiscence have common auditory-vestibular features regardless of which of the two vertical semicircular canals is affected. The only obvious difference between the two is the vertical component of the sound and pressure-induced eye movements (which beats in opposite directions).

The Reproducibility of Blur with a Bangerter Filter

Background: Bangerter filters before the sound eye are an accepted method of treating mild amblyopia. The visual acuity fraction labeling is considered by some not to be reliable. Our purpose was to analyze the visual degradation caused by the filter and to evaluate the consistency of these objective measures for a set of filters of the same labeled density. Methods: Twelve new 0.2 density Bangerter filters and a single 0.1 and 0.4 filter were obtained. A sine-wave grating was analyzed through each filter producing a spatial frequency response (SFR) that measures the degradation of the grating.

Representation of Eye Position in Primate Inferior Colliculus

We studied the representation of eye-position information in the primate inferior colliculus (IC). Monkeys fixated visual stimuli at one of eight or nine locations along the horizontal meridian between -24 and 24 degrees while sounds were presented from loudspeakers at locations within that same range. Approximately 40% of our sample of 153 neurons showed statistically significant sensitivity to eye position during either the presentation of an auditory stimulus or in the absence of sound (Bonferroni corrected P < 0.05). The representation for eye position was predominantly monotonic and favored contralateral eye positions. Eye-position sensitivity was more prevalent among neurons without sound-location sensitivity: about half of neurons that were insensitive to sound location were sensitive to eye position, whereas only about one-quarter of sound-location-sensitive neurons were also sensitive to eye position. Our findings suggest that sound location and eye position are encoded using independent but overlapping rate codes at the level of the IC. The use of a common format has computational advantages for integrating these two signals. The differential distribution of eye-position sensitivity and sound-location sensitivity suggests that this process has begun by the level of the IC but is not yet complete at this stage. We discuss how these signals might fit into Groh and Sparks' vector subtraction model for coordinate transformations.

Properties of Saccades in Duane Retraction Syndrome

To improve understanding of the binocular control of saccades by making high-resolution eye movement recordings in patients with unilateral Duane retraction syndrome (DRS) type I (marked by congenital absence of the sixth cranial nerve). Binocular eye movements were recorded in four patients in binocular viewing conditions during a saccade task. Affected-side gaze showed normal saccades of the sound eye and undershooting saccades of the affected eye-evidence of intact interneurons, but deficient motoneurons, in the sixth-nerve nucleus on the affected side. Postsaccadic smooth onward drift followed undershooting saccades of the affected eye. Sound-side gaze, in the centripetal direction, showed relatively accurate saccades despite large offsets in initial position between the two eyes. In the centrifugal direction, there was a consistent undershoot of the affected eye. The sound eye showed unexpected overshoot. Postsaccadic drifts in opposite directions in the two eyes brought both eyes onto the target in an optimal time course. Studying the characteristics of the saccadic system in this oculomotor disorder gives new insight into binocular control of saccades and adaptation. In these patients, the oculomotor system was not capable of adapting the pulse command to the two eyes separately, even though DRS offers clear advantages of independent control. In contrast, independent adaptation of the saccadic step command was sent to the two eyes. This supports the idea that the rapid part of the saccadic command is common to both eyes.

Evaluating reading acuity and speed in children with microstrabismic amblyopia using a standardized reading chart system

To examine if standardized reading charts with highly comparable test items can be used for evaluating impairments in the monocular reading performance of children with microstrabismic amblyopia characterized by a small angle of squint with less than 5 degrees. The reading performance of 22 children (mean age: 11.7+/-1.6 years) with unilateral microstrabismic amblyopia was evaluated monocularly in both eyes, using standardized reading charts for the simultaneous determination of reading acuity and speed. The print sizes of the highly comparable sentence optotypes were logarithmically graded, providing constant geometric proportions for all testing distances in order to control contour interaction. All children were under continuous amblyopia therapy. In the amblyopic eyes, reading acuity and maximum reading speed were significantly impaired when compared to the sound fellow eyes (P<0.001). In respect of the maximum reading speed, a mean inter-ocular difference of 33+/-19 words per minute was found, revealing functionally relevant deficits in monocular reading performance. The amblyopic eyes achieved only a significantly reduced reading acuity (mean inter-ocular difference: LogRAD 0.5+/-0.24; P<0.001). In eight children, the amblyopic eyes achieved a best-corrected visual acuity of LogMAR 0.0 or better: in respect of the visual acuity, there was no significant inter-ocular difference, but reading acuity and maximum reading speed were significantly impaired when compared to the fellow eyes. Microstrabismic amblyopia was associated with significant impairment of reading acuity and speed in treated amblyopes, even in those with no persistent acuity deficit. To improve treatment addressing these functional deficits, reading performance should be monitored over time using standardized reading tests, which provide essential information about functionally relevant reading impairments.