Stereoacuity In Patients Research Articles

Correlation between Central Visual Field Defects and Stereopsis in Patients with Early-to-Moderate Visual Field Loss

To investigate the association between stereoacuity and the presence of central visual field defects (CVFDs) due to glaucoma. A prospective, cross-sectional cohort study. Participants with early-to-moderate glaucoma with a visual acuity better than 20/40, less than a 2-line difference in visual acuity between eyes, and 2 reliable Humphrey visual fields (VFs) (24-2 SITA standard) with mean deviation (MD) in the worse eye better than-12 dB. Stereoacuity was measured using the Titmus stereo test. Participants with a significant field defect (P<0.005) in any 1 of the central 4 points in the 24-2 SITA standard total deviation map in either eye were classified as having a CVFD. Vision-related quality of life (VR-QOL) was measured using 25-item National Eye Institute Visual Function Questionnaire scores. Logistic regression was used to determine the associations between the level of stereoacuity and age, sex, race, glaucoma type, presence of CVFDs, visual acuity, contrast sensitivity, and VF MD. Stereoacuity in the CVFD and non-CVFD groups. Sixty-five participants met the inclusion criteria. The mean age of the participants was 64.3±8.0 years, and 64.6% were women. The median stereoacuity was 60 arc seconds (interquartile range [IQR], 40-120 arc seconds). Forty-two (65%) patients had CVFDs, and 23 (35%) patients did not. The median stereoacuity of the CVFD group was worse than that of the non-CVFD group (60 arc seconds [IQR, 50-140 arc seconds] vs. 40 arc seconds [IQR, 40-80 arc seconds], respectively; P=0.001). The non-CVFD group had a higher percentage of participants with normal stereopsis than the non-CVFD group (61% vs. 21%, respectively; P=0.001). A multivariable analysis found that the presence of CVFDs was associated with worse stereopsis levels (odds ratio, 4.49; P=0.021). The CVFD group had a lower Visual Functioning Questionnaire-25 (VFQ-25) composite score (84.0 vs. 91.4; P=0.004) and lower VFQ-25 subscale scores for general vision, near activities, and mental health (P<0.05). Central visual field defects were associated with increased odds of poor stereoacuity in patients with early-to-moderate glaucomatous VF loss. Specifically, patients without CVFDs are more likely to have normal stereopsis and higher VR-QOL than those with CVFDs. Patients with CVFDs should be counseled regarding how depth perception difficulties may affect daily living. Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.

Stereoacuity in Patients with Non-Amblyopic Anisometropia

Purpose: To compare the stereoacuity between patients with uncorrected and corrected non-amblyopic anisometropia, and to evaluate the correlation between the degrees of anisometropia and stereoacuity.Methods: We retrospectively reviewed the records of patients with non-amblyopic anisometropia who underwent the stereoacuity test. Patients were divided into uncorrected anisometropia (n = 33) and corrected by spectacles (n = 30) groups. The clinical characteristics and sensory status of patients were evaluated using the Worth 4-dot, Titmus, Lang II, and TNO tests, and compared between the groups. Correlation analysis was performed between the degree of anisometropia and the level of stereopsis.Results: The uncorrected and corrected anisometropia groups did not significantly differ in mean age (12.2 ± 3.7 and 11.8 ± 4.0 years) or degree of anisometropia (2.12 ± 1.21 and 1.81 ± 1.25 diopters). The rate of sensory fusion in the distant Worth 4-dot test was lower in the uncorrected anisometropia than the corrected anisometropia group. The level of stereopsis was also worse in the uncorrected anisometropia than the corrected anisometropia group in all stereoacuity tests. There was a strong positive correlation between the degree of anisometropia and the level of stereoacuity on the Titmus, Lang II, and TNO tests (r = 0.690, r = 0.614, and r = 0.655, respectively; all p &lt; 0.001) in the uncorrected anisometropia group. However, the corrected anisometropia group showed a weak positive correlation between the degree of anisometropia and the level of stereoacuity only on the TNO test (r = 0.366; p = 0.047).Conclusions: Stereoacuity was better in the corrected anisometropia group than in the uncorrected group. It significantly worsened with increasing anisometropia in the uncorrected group, but only a weak correlation was observed in the corrected group. Therefore, prescribing glasses could be recommended to improve stereopsis in adolescents and young adults with anisometropia.

Comparison of stereoacuity in patients of anisometropia, isometropia and emmetropia.

To compare the stereoacuity in patients with anisometropia, isometropia, and emmetropia. A cross-sectional study was conducted on 1403 subjects (range: 5-45 years) divided into anisometropes (n = 403), isometropes (n = 500), and emmetropes (n = 500). There were 258 amblyopic eyes among anisometropes and 156 amblyopic eyes among isometropes. Stereoacuity was measured using the Titmus stereo test consisting of a combination of contour targets. There were 675 males and 728 females. A significant (P < 0.001) reduction in stereoacuity was found in anisometropes as compared to isometropes and emmetropes. The stereoacuity was even worse in amblyopes as compared to non-amblyopes. Most patients with anisometropia of <3.0 D had fair stereoacuity. However, as the degree of anisometropia increased to >3.0 D, stereoacuity deteriorated gradually. Marked reduction of stereoacuity was observed in severe degree of anisometropia (>6.0 D). Overall, an anisometropia of ≥2.12 D was associated with reduced stereoacuity. Among the anisometropes, it was found to be the poorest in myopia, followed by myopia with astigmatism, hypermetropia with astigmatism, and hypermetropia. The level of stereoacuity was worse in anisometropes as compared to isometropes and emmetropes. Amblyopes had a greater reduction in stereoacuity than non-amblyopes. Stereoacuity decreased as the degree of anisometropia increased. Among the anisometropes, myopes had worst stereoacuity than hypermetropes.

Binocular Visual Function Changes After Corneal Collagen Cross-linking in Patients With Keratoconus.

High-order aberrations (HOAs) have been demonstrated to profoundly affect both visual acuity and stereoacuity in patients with keratoconus. Corneal collagen cross-linking (CXL) has been proven to significantly lower HOAs in keratoconus. Yet, to the present date, no evaluation of the effect of the procedure on stereopsis has been performed. The purpose of the study was to assess differences in binocular visual performance in patients with keratoconus before and after CXL. Patients with keratoconus undergoing standard Dresden protocol epi-off CXL in the ophthalmology department of Policlinico Universitario Agostino Gemelli Hospital received slitlamp examination, uncorrected distance visual acuity and corrected distance visual acuity assessment, corneal tomography, Lang stereotest, TNO stereoacuity assessment, distance and near cover test, and Irvine test before surgery and 6 months after CXL. Stereopsis tests were performed with spectacle correction. The analysis included 30 patients (mean age 24.63 ± 3.49 years). The Lang test improved after treatment ( P 0.027), with 6 of 30 patients (20%) showing a positive Lang test before CXL compared with 16 of 30 patients (53.3%) after treatment. Moreover, TNO stereoacuity increased after treatment ( P 0.043), and 14 of 30 patients (46.7%) manifested an improvement of at least 250″ at the TNO test after CXL. In this subgroup of patients, total root mean square values decreased after treatment ( P < 0.001), whereas patients who did not manifest a clinically significant improvement in stereoacuity did not show a reduction in total root mean square values after CXL ( P = 0.11). The results of cover test and Irvine test did not vary after CXL. Patients with keratoconus showing a reduction of HOAs after CXL also manifest a significant improvement in stereoacuity after the treatment.

Aniseikonia and visual functions with optical correction and after refractive surgery in axial anisometropia.

To evaluate differences in the subjective aniseikonia and stereoacuity in patients with axial anisometropia after full correction of the refractive error with spectacles, contact lenses, and refractive surgery. A prospective study was performed in Cairo University Hospitals on 20 patients with axial anisometropia caused by unilateral myopia > 5 D with > 4 D inter-ocular difference in spherical equivalent who were suitable candidates for excimer laser ablation (LASIK) or implantable collamer lens implantation (ICL). All patients had measurement of best-corrected visual acuity (BCVA), fusion, stereoacuity, and magnitude of aniseikonia with spectacles, contact lenses, and after surgery. The mean age at time of surgery was 25.7 ± 3.1years. There were no statistically significant differences in the BCVA or stereoacuity with spectacles, contact lenses, or after refractive surgery. Microkonia < 5%) was perceived with spectacles in 8 patients (40%) and remained unchanged in 7 of these 8 patients with contact lenses. Following LASIK (n = 11), there was an induced macrokonia < 2% in 4 patients (36%), persistent microkonia of 3% in 1 patient (9%), and no change in image size in 6 (55%) patients. Following ICL implantation (n = 9), there was a perceived macrokonia of 2% in 4 patients (44%), disappearance of microkonia in 1 patient (11%) and no change in 4 patients (44%). Differences in BCVA, stereoacuity, and aniseikonia after correction of anisometropia by glasses, contact lens and surgery are both clinically and statistically insignificant. Retinal or neural adaptation might have a role in correction for differences in image size.

A comparative study of stereoacuity in patients with various grades of cataract and bilateral pseudophakia.

Purpose:To compare the stereopsis in patients with various grades of cataract and bilateral pseudophakia.Methods:A cross-sectional observational study was conducted at a tertiary care center in South India from December 2016 to September 2018, wherein the stereoacuity of patients having bilateral senile cataract or bilateral pseudophakia, was measured using the Titmus Fly chart. Those with any form of squint, glaucoma or retinal pathology were excluded. The patients were divided into three groups based on the severity of cataract, determined by the Lens Opacification Classification System (LOCS)-III. Group 4 included those with bilateral pseudophakia. Statistical analysis was performed using one-way ANOVA test with post hoc analysis using the Bonferroni test, to study the difference of stereoacuity between the groups.Results:A total of 200 patients were evaluated. The mean stereoacuity was 65.2 ± 18.2, 114.8 ± 83.42, 402.4 ± 223.7 and 107.2 ± 71.68 arc seconds in groups 1, 2, 3 and 4, respectively (P < 0.001). The mean best corrected visual acuity (BCVA) in LogMAR units was 0.19 ± 0.15, 0.37 ± 0.24, 0.82 ± 0.26 and 0.14 ± 0.13 in groups 1, 2, 3 and 4, respectively (P = 0.01). On comparison between four groups, there was a generalised decrease in BCVA and stereoacuity with increasing grades of cataract except for group 4 which included the bilateral pseudophakics. On post hoc analysis to analyse intergroup variation a statistically significant difference in stereo acuity was noticed when group 3 was compared to other groups.Conclusion:Stereoacuity decreases with increasing grades of cataract. Better stereoacuity is seen in patients with bilateral pseudophakia when compared with high grades of cataract.

Near and Distance Stereoacuity in Patients With Primary Open-angle Glaucoma.

To compare near and distance stereoacuity between patients with primary open-angle glaucoma (POAG) and a control group, and to analyze the associations between stereoacuity and POAG severity. This cross-sectional study compared near and distance stereoacuity between the POAG and control groups. The data from the POAG group were used to assess the associations between stereoacuity (both near and distance) and the severity of visual field (VF) defects (based on Hodapp-Anderson-Parrish classification and the VF index). The study included 94 eyes of 47 patients with POAG and 80 eyes of 40 control subjects. Near and distance stereoacuity were significantly lower in the POAG group than in the control group (both P<0.001). Near stereoacuity worsened with POAG severity in terms of both the Hodapp-Anderson-Parrish classification and VF index (P=0.007 and P=0.049, respectively). However, distance stereoacuity was not associated with POAG severity for either categorization (P=0.12 and P=0.57, respectively). The proportions of patients with reduced near stereoacuity and those with a lack of distance stereoacuity were higher in the POAG group than in the control group. Near and distance stereoacuity were significantly lower among patients with POAG than among control subjects. Near stereoacuity worsened with increasing POAG severity but distance stereoacuity did not. However, the proportion of patients with a lack of distance stereoacuity was higher in the POAG group than in the control group.

Stereoacuity outcomes following surgical correction of the nonaccommodative component in partially accommodative esotropia

Previous studies of partially accommodative esotropia (PAET) have assessed factors requiring surgery and alignment outcomes. The purpose of the present study was to additionally evaluate stereoacuity in patients who required surgery for their nonaccommodative component. The medical records of consecutive patients with PAET who underwent bilateral medial rectus recession from April 1990 to July 2010 to treat the nonaccommodative component were reviewed retrospectively. Preoperative data included visual acuity, stereoacuity, cycloplegic refraction, deviation at distance and near, and age at surgery. The primary outcomes were stereoacuity and alignment. A total of 84 patients were included. Stereopsis by the Titmus StereoTest was demonstrated in 51 (61%) by the final visit. The average follow-up time was 4.4±2.8years (range, 0.8-11.0years). Fine stereopsis (100 arcsec or better) was appreciated in 29 patients(35%, 57% of those with stereopsis). Of those with residual esotropia, 11 (50%) demonstrated stereopsis, and 7 (32%) appreciated fine stereoacuity. No exotropic patient had stereopsis. There was a statistically significant correlation between age at time of surgery and stereopsis at 1year (ρ=0.233; P=0.033) but not at the final visit (ρ=0.106, P=0.34). Of the 84 patients, 56 (67%) had a favorable alignment (within 10Δ of orthotropia) at the final visit; 22 (26%) had residual esotropia; and 6 (7%) had consecutive exotropia. In this subset of esotropic patients who required surgery for their nonaccommodative component, favorable sensory outcomes can be achieved. Furthermore, favorable stereoacuity can be found even when there is a residual esodeviation.

Improvement in fusion and stereopsis following surgery for intermittent exotropia.

To evaluate fusion stereopsis in patients with intermittent exotropia before and after strabismus surgery. Fifty-three patients (mean age: 11.8 years, range: 5 to 25 years) with intermittent exotropia were enrolled. Fusion was measured with the Worth 4-dot test. Near stereopsis was examined with Titmus and stereoscopic test charts (created in China by Shao-Ming Yan). Distance stereopsis was tested with random-dot stereograms produced by Tianjin Eye Hospital. All patients completed the tests preoperatively and 2 and 6 weeks postoperatively. There were no statistically significant differences in stereoscopic test charts among groups preoperatively (P > .05) and postoperatively (P > .05) or on Titmus tests preoperatively (P > .05) and postoperatively (P > .05). Among 53 patients, the percentage of distance stereoscopic improvement was 49% after 2 weeks and 77% after 6 weeks compared to 13% preoperatively. Six weeks postoperatively, random-dot stereograms were significantly different in those younger than 7 years and older than 13 years (P < .05), as well as those 7 to 13 years and older than 13 years (P < .05). Fifty (94%) demonstrated peripheral fusion and only 21 (40%) demonstrated central fusion preoperatively. Six weeks postoperatively, all patients exhibited peripheral fusion and 52 (98%) demonstrated central fusion. Central fusion in patients with intermittent exotropia significantly increased after 6 weeks (chi-square = 42.29, P < .01). Patients with intermittent exotropia have good near stereoacuity preoperatively and postoperatively. Even if surgery is postponed until adolescence, distance stereopsis can still be recovered. Surgical intervention can restore central fusion and stereoacuity in patients with intermittent exotropia.

Stereo-Acuity in Patients Implanted with Multifocal Intraocular Lenses: Is the Choice of Stereotest Relevant?

Purpose: A randomized and double-blinded study design was implemented to assess the stereo-acuity in patients symmetrically implanted with four types of multifocal intraocular lenses (MIOLs), compared to a monofocal lens (control group). In addition, the influence of the type of test employed for the evaluation of stereo-acuity was explored.Materials and Methods: Six months after cataract intervention, stereo-acuity was measured with the Titmus and TNO stereotests in 143 patients implanted with one of the following MIOL lens types: hybrid spherical SN60D3, hybrid aspheric SN6AD1, diffractive aspheric ZMA00 and refractive spherical NXG1. A control group implanted with the monofocal aspheric ZA9003 (in which stereo-acuity was measured with a near addition) was also included in the study.Results: Statistically significant better stereo-acuity was found in the monofocal group with both stereotests (except for the SN60D3 group with the Titmus test) (all p < 0.001). No significant differences in stereo-acuity between MIOLs were found using the Titmus test. However, with the TNO, patients implanted with hybrid diffractive MIOLs exhibited statistically significant worse stereo-acuity than those with the refractive design (SN60D3, p < 0.001; SN6AD1, p = 0.006).Conclusions: Patients implanted with MIOLs have worse stereo-acuity than those implanted with monofocal IOLs due to the decrease in retinal image contrast originating in the simultaneous presence of two images. A wavelength-based stereotest such as the TNO induces large differences in image contrast between fellow eyes implanted with diffractive-based MIOLs, which may result in an underestimation of the real stereo-acuity of the patient.

To evaluate stereoacuity in patients with acquired esotropia and to determine factors associated with favourable outcomes.

Aim:To evaluate stereoacuity in patients with acquired esotropia and determine the factors associated with favorable outcomes.Materials and Methods:A total of 68 subjects aged 6 years and above were included in the study. Thorough clinical evaluation including binocular status examination using the Bagolini-striated glass test, The Netherland Organization (TNO), and Randot stereo test were done. The subjects were divided into two groups 1 and 2, based on the amount of deviation. Statistical analysis of the result was performed.Result:The duration of misalignment in the group with deviation less than or equal to 8 prism diopters (PD) was 1.49 ± 0.86 years, whereas in the group with deviation more than or equal to 10 PD was 4.64 ± 2.99 years (P = 0.000). Among the subjects in group 1, 89.5% achieved fusion and 52.6% had stereoacuity on both TNO and Randot, whereas in group 2 40% achieved fusion and 3.3% stereopsis on both TNO and Randot (one case with only coarse stereopsis). A subanalysis within group 1 revealed a statistically significant difference for the duration of misalignment (P = 0.02), but a marginal difference for the amount of deviation (P = 0.3).Conclusion:A horizontal deviation up to 8 PD was compatible with stereopsis. Also, the duration of constant misalignment affects the attainment of stereopsis despite successful realignment.

The Initial Factors Influencing Successful Final Stereoacuity in Refractive Accommodative Esotropia

Purpose: To evaluate the initial factors influencing successful final stereoacuity in patients with refractive accommodative esotropia. Methods: The charts of 48 refractive accommodative esotropia patients 2 years of age or older andassessed using the Titmus stereoacuity test were retrospectively reviewed. Hyperopic refractive error on post-cycloplegic refraction, age at first glasses, stereoacuity after refractive correction and amblyopia were categorized and evaluated as the factors influencing final stereoacuity. Results: The mean follow-up period was 43.51 ± 30.02 months. The mean hypermetropia at the initial examination was 4.67 ± 2.18 diopters (D), the mean age at first glasses was 48.09 ± 20.22 months and the mean stereoacuity after refractive correction was 1243.75 ± 1378.24 seconds of arc. The rates of successful stereoacuity at the final visit were 83.3% without amblyopia, 75.0% with mild amblyopia and 42.9% with moderate amblyopia which were statistically significant (p = 0.039). Hyperopic refractive error and age at first glasses were categorized as +1.0 to <3.0 D, +3.0 to <5.0 D, ≥+5.0 D and 2 to <4 years, 4 to <6 years and ≥6 years, respectively, and the rates of successful stereoacuity at the final visit were 83.3%, 66.7%, 61.9% (p = 0.362) and 71.4%, 75.0% and 54.5% (p = 0.334), respectively. Conclusions: The amblyopia at the initial examination was significantly associated with the outcome of stereoacuity at the final visit in patients with refractive accommodative esotropia. J Korean Ophthalmol Soc 2014;55(6):877-881

Perceptual Relearning of Binocular Fusion and Stereoacuity After Brain Injury

Background. Brain lesions may disturb binocular fusion and stereopsis, leading to blurred vision, diplopia, and reduced binocular depth perception for which no evaluated treatment is currently available. Objective. The study evaluated the effects of a novel binocular vision treatment designed to improve convergent fusional amplitude and stereoacuity in patients with stroke or traumatic brain injury (TBI). Methods. Patients (20 in all: 11 with stroke, 9 with TBI) were tested in fusional convergence, stereoacuity, near/far visual acuity, accommodation, and subjective binocular reading time until diplopia emerged at 6 different time points. All participants were treated in a single subject baseline design, with 3 baseline assessments before treatment (pretherapy), an assessment immediately after a 6-week treatment period (posttherapy), and 2 follow-up tests 3 and 6 months after treatment. Patients received a novel fusion and dichoptic training using 3 different devices to slowly increase fusional and disparity angles. Results. At pretherapy, the stroke and TBI groups showed severe impairments in convergent fusional range, stereoacuity, subjective reading duration, and partially in accommodation (only TBI group). After treatment, both groups showed considerable improvements in all these variables as well as slightly increased near visual acuity. No significant changes were observed during the pretherapy and follow-up periods, ruling out spontaneous recovery and demonstrating long-term stability of binocular treatment effects. Conclusions. This proof-of-principle study indicates a substantial treatment-induced plasticity of the lesioned brain in the relearning of binocular fusion and stereovision, thus providing new, effective rehabilitation strategies to treat binocular vision deficits resulting from permanent visual cortical damage.

Stereopsis in bilaterally multifocal pseudophakic patients

The purpose of this study was to evaluate stereoacuity in patients with bilateral implantation of an aspheric bifocal intraocular lens (IOL). Thirty patients scheduled for cataract surgery were implanted with the aspheric bifocal AcrySof ReSTOR IOL. Stereoacuity was measured using the vectographic Titmus and Random dot stereotests (fixed disparity) and the Howard–Dolman apparatus (threshold disparity) under photopic conditions (85 cd/m2) after phacoemulsification for cataract surgery in 30 patients with low astigmatism (≤1D). Visual acuity at distance and near was also examined. All patients were examined at 1-year follow-up. Mean stereoacuity with the Titmus and the Random dot sterereotests was 44.55 ± 1.08 sec arc (range, from 40 to 80) and 41.25 ± 1.12 sec arc (range, from 20 to 70) respectively. The Howard–Dolman method showed a mean value of 18.42 ± 6.10 sec arc, ranging from 11 to 30 sec arc. No statistically significant differences were found between the Titmus and the Random dot sterereotests values (P = 0.189). However, these values differ significantly from that found using the Howard-Dolman method (P = 0.005). Visual acuity at distance and near was 0.04 ± 0.05 and 0.04 ± 0.04 logMAR (about 20/20) respectively. Despite simultaneous images on the retina after bifocal IOL implantation, patients showed useful stereoacuity. This study confirms that retinal image blur associated with multifocality does not deteriorate stereoacuity. Stereoscopic threshold measurement with a Howard–Dolman apparatus is more accurate than vectographic tests when assessing stereoacuity after IOL surgery.

Stereoacuity in Patients with Schizophrenia

Stereoacuity in Patients with Schizophrenia

Factors Affecting Stereopsis After Pediatric Cataract Surgery

Purpose: To evaluate factors influencing stereoacuity outcomes after pediatric cataract surgery. Methods: We retrospectively reviewed 38 eyes of 22 patients who had undergone irrigation and aspiration of cataracts and primary posterior chamber intraocular lens implantation from February 1992 to July 2006. In all patients, stereoacuity was assessed with the Titmus stereo test. Patients were divided into two groups according to stereoacuity: group 1 (n=9) had a stereoacuity less than 100 sec/arc; group 2 (n=13) had a stereoacuity more than 100 sec/arc. Nine variables associated with stereoacuity were evaluated in each group. Results: Postoperative strabismus was the strongest factor influencing the stereoacuity level. Good postoperative mean visual acuity was related with good stereoacuity. Though mean visual acuity in two children with exodeviation over 30PD was 0.7 and 0.8, their stereoacuity was 400 sec/arc. Showing little difference in the spherical equivalent between the eyes was also related to good stereoacuity. Conclusions: Postoperative strabismus onset, postoperative mean visual acuity between the two eyes, and differences in the spherical equivalent were important factors influencing stereoacuity in patients after pediatric cataract surgery.

Assessment of a New Distance Randot Stereoacuity Test

We sought to develop a new "Distance Randot" test, establish a normative data set for children and adults, and compare with established measures of stereoacuity. Distance Randot, distance Frisby-Davis 2 (FD2), and near Preschool Randot stereoacuity (Stereo Optical Co., Inc., Chicago, IL) were assessed in 23 normal children (ages 4-14 years), 21 normal adults (ages 20-36 years), and 131 patients with a variety of strabismic conditions (ages 4-85 years). For each test, stereoacuity was defined as the smallest disparity in which 2 targets were correctly identified. The simultaneous prism and cover test (SPCT) and the alternate prism and cover test (APCT) were used to assess misalignment. For the new Distance Randot test, normative results were similar to published data obtained with established near and distance stereoacuity tests. In the patient cohort, comparing stereoacuity data obtained from Distance Randot stereoacuity test and the Near Preschool Randot stereoacuity test, most of the patients with discordant scores had poorer distance than near stereoacuity. Comparing the Distance Randot stereoacuity test and the Distance FD2, all of the patients with discordant scores had poorer Distance Randot than FD2 scores. Distance Randot test is more likely to detect abnormalities in distance stereopsis and may provide a useful tool in measuring distance stereoacuity in patients with and without strabismus. However, further studies are needed to define the efficacy of the Distance Randot test in monitoring progression specific conditions such as intermittent exotropia, where it may prove useful as a guide to the timing of intervention.

Stereopsis in bilaterally pseudophakic patients

Purpose: To investigate the stereoacuity in patients who have had implantation of a monofocal intraocular lens (IOL) in each eye and to identify the principal risk factors for impaired stereoacuity. Setting: Hayashi Eye Hospital, Fukuoka, Japan. Methods: One hundred patients scheduled for bilateral phacoemulsification and monofocal IOL implantation were recruited. Near stereoacuity was measured approximately 2 weeks after surgery using the Titmus test. Various parameters that may be associated with stereoacuity in pseudophakic patients were measured using the New Aniseikonia Test (Handaya Corp.). Parameters included age, visual acuity, spherical equivalent, astigmatism, axial length, pupil diameters, IOL decentration and tilt, and aniseikonia. Stepwise multiple regression analysis was performed to identify independent predictors of impaired stereoacuity. Results: The mean stereoacuity was 57.1 seconds of arc ± 36.9 (SD); 90 patients (90%) had a good stereoacuity (ie, 100 seconds of arc or better). Simple regression analysis showed that a larger difference in spherical equivalent between fellow eyes and older age was significantly associated with poor stereoacuity. The best final model ( R 2 = 0.375) in the multiple regression analysis identified a greater difference in spherical equivalent to be the most significant predictor of impaired stereoacuity, followed by older age and a larger pupil diameter. Conclusions: Ninety percent of patients with bilateral pseudophakia had useful stereoacuity. The main risk factor for poor stereoacuity was a greater difference in the spherical equivalent between the eyes, followed by older age and a larger pupil diameter. These results indicate the need for an accurate preoperative IOL power calculation.

The use of binocular visual acuity in the assessment of intermittent exotropia

Background: It has been suggested that a decrease in distance stereoacuity in patients with intermittent exotropia is a good indicator of diminishing control. However, there has been no adequate explanation for this reported reduction in distance stereoacuity in these patients. We postulate that the decrease in stereoacuity is related to blurred visual acuity created by an increasing demand on accommodation, which these patients use in an attempt to control the exodeviation. This can best be assessed by measuring binocular visual acuity (BVA). Analysis of BVA could provide a useful clinical tool to evaluate control measures used by patients with intermittent exotropia. Methods: A prospective study of patients with intermittent exotropia, ranging in age from 6 to 60 years, was performed. Only those patients with the presence of either basic or divergence excess (simulated or true) type exodeviation were included in the study. The data analysis included the age of these patients, age at onset of the deviation, monocular and binocular visual acuity, oculomotor and fusional status, and near and distance stereoacuity. Results: Data from 36 patients show that the measurements of BVA correlated well with a corresponding loss of distance stereoacuity but not with the size of the deviation. Conclusion: The decrease of stereoacuity reported in patients with exotropia can be explained by increased accommodation and decreased distance BVA. This measurement can be a simple method of quantifying the fusional control of patients with intermittent exotropia. (J AAPOS 2000;4:154–7)

Assessment of central and peripheral fusion and near and distance stereoacuity in intermittent exotropic patients before and after strabismus surgery

PURPOSE: To determine whether central fusion and distance stereoacuity are useful as objective measures in assessing the need for and success of surgery for intermittent exotropia (X[T]). METHODS: A prospective, institutional, clinical trial was conducted of 26 consecutive patients with X(T) who were undergoing strabismus surgery in whom fusion (central and peripheral) and stereoacuity (at near and distance) were assessed preoperatively and postoperatively, as well as in 112 normal subjects. To obtain accurate measurements with sensory tests, the lower age was limited to 5 years for inclusion. A successful surgical alignment was defined as an exotropia of 10 prism diopters or less at 6 m. Sensory and motor outcome measures were determined 1 year after surgery. RESULTS: The successful surgical alignment rate was 69%. All patients with X(T) demonstrated peripheral fusion, whereas 35% demonstrated central suppression preoperatively and postoperatively. Central fusion was not predictive of surgical outcome ( P = .078); however, there was a trend toward less surgical success in patients with central suppression. Patients with X(T) exhibited good near stereoacuity before and after surgery. Distance stereoacuity in patients with X(T) preoperatively was significantly diminished compared with normal subjects ( P < .001) and was improved in 58% postoperatively. Patients who achieved successful surgical alignment had a greater likelihood of demonstrating distance stereoacuity improvement postoperatively than patients who failed to achieve successful surgical alignment ( P = .003). Patients with central suppression were unlikely to improve their distance stereoacuity postoperatively ( P = .014). CONCLUSIONS: Successful surgery may improve distance stereoacuity. Better distance stereoacuity and central fusion are frequently associated with better surgical success in X(T).