Defining real change in measures of stereoacuity.

PURPOSE: To establish the thresholds for "real change" in stereoacuity by defining long-term test-retest variability as 95% limits of agreement for 4 stereoacuity tests. DESIGN: Retrospective cohort study. PARTICIPANTS AND CONTROLS: We identified 36 patients (median, 17 years; range, 7-76) with any type of stable strabismus who had stereoacuity measured on 2 consecutive visits. Stable strabismus was defined as angle of deviation within 5 prism diopters by simultaneous prism and cover test and prism and alternating cover test. METHODS: Stereoacuity was measured at near using the preschool Randot and the near Frisby stereotests and at distance using the Frisby-Davis distance (FD2) and the distance Randot stereotests. Stereoacuity was transformed to log units for analysis. The 95% limits of agreement were calculated based on a 1.96 multiple of the standard deviation of differences between test and retest. MAIN OUTCOME MEASURES: The 95% limits of agreement for change in stereoacuity thresholds at 2 consecutive visits. RESULTS: The 95% limits of agreement were 0.59 log arcsec for the preschool Randot, 0.24 for the near Frisby, 0.68 for the FD2, and 0.46 for the distance Randot. These values correspond with the following octave steps (doublings of threshold; e.g., 200-400 arcsec): preschool Randot, 1.95; near Frisby, 0.78; FD2, 2.27; and distance Randot, 1.52. CONCLUSIONS: A change of approximately 2 octaves of stereoacuity threshold are needed to exceed test-retest variability for most stereoacuity tests. Changes <2 octaves cannot be distinguished from test-retest variability. When used to guide patient management, caution should be taken in interpreting changes in stereoacuity of <2 octaves. FINANCIAL DISCLOSURE(S): The authors have no proprietary or commercial interest in any materials discussed in this article.

Strabismus surgery for internuclear ophthalmoplegia with exotropia in multiple sclerosis.

BACKGROUND: Internuclear ophthalmoplegia (INO) is a disabling condition affecting up to 40% of patients with multiple sclerosis (MS). Management of bilateral internuclear ophthalmoplegia (BINO) with exotropia in MS has been controversial because of the uncertain course of MS. Diplopia associated with INO severely impacts the patient's quality of life and, therefore, treatment should be considered. METHODS: Three patients (ages 28, 62, and 82 years) who had BINO with exotropia and disabling diplopia secondary to MS underwent bilateral medial rectus resections with either unilateral or bilateral adjustable lateral rectus recession(s). Alignment was measured preoperatively and postoperatively, and symptoms were recorded. RESULTS: Preoperative exotropia ranged from 40(Delta) to 64(Delta) for distance fixation and from 50(Delta) to 70(Delta) for near fixation. Preoperatively, all patients had diplopia at distance and near fixation. Immediately after surgery, patients were adjusted to 10(Delta) to 18(Delta) ET at distance fixation with the expectation of an exotropic drift. None of the patients had a tropia at distance and near fixation 6 months after surgery, with single vision in primary position and reading. Two patients had a 2-year follow-up examination; 1 required a small amount of base-in prism for comfortable reading. CONCLUSIONS: Three patients who had BINO with exotropia secondary to MS all benefited from surgery. Surgery should be considered as an option for symptomatic patients who have BINO with exotropia caused by MS.

The effect of induced monocular blur on measures of stereoacuity.

PURPOSE: To determine the effect of induced monocular blur on stereoacuity measured with real depth and random dot tests. METHODS: Monocular visual acuity deficits (range, 20/15 to 20/1600) were induced with 7 different Bangerter filters (<0.1, 0.1, 0.2, 0.3, 0.4, 0.8, and 1.0) in 15 visually normal adults. Stereoacuity was measured with Frisby and Frisby Davis Distance (FD2) real depth tests and Preschool Randot (PSR) and Distance Randot (DR) random dot tests. Stereoacuity results were grouped as either "fine" (60 and 200 arcsec to nil) stereo. RESULTS: Across visual acuity deficits, stereoacuity was more severely degraded with random dot (PSR, DR) than with real depth (Frisby, FD2) tests. Degradation to worse-than-fine stereoacuity consistently occurred at 0.7 logMAR (20/100) or worse for Frisby, 0.1 logMAR (20/25) or worse for PSR, and 0.1 logMAR (20/25) or worse for FD2. There was no meaningful threshold for the DR because worse-than-fine stereoacuity was associated with -0.1 logMAR (20/15). Course/nil stereoacuity was consistently associated with 1.2 logMAR (20/320) or worse for Frisby, 0.8 logMAR (20/125) or worse for PSR, 1.1 logMAR (20/250) or worse for FD2, and 0.5 logMAR (20/63) or worse for DR. CONCLUSIONS: Stereoacuity thresholds are more easily degraded by reduced monocular visual acuity with the use of random dot tests (PSR and DR) than real depth tests (Frisby and FD2). We have defined levels of monocular visual acuity degradation associated with fine and nil stereoacuity. These findings have important implications for testing stereoacuity in clinical populations.

Quality of life in intermittent exotropia: child and parent concerns.

OBJECTIVE: To identify specific health-related quality-of-life (HRQOL) concerns for children with intermittent exotropia (IXT) and their parents. METHODS: Twenty-four children aged 5 to 17 years with IXT and 1 parent for each child were recruited. Individual interviews with the child and then the parent were audiotaped and transcribed. Transcripts were reviewed, phrases regarding effects of IXT on HRQOL recorded, and specific topic areas identified. Topic frequency was analyzed to determine children's perceptions of their own HRQOL, parents' perceptions of their child's HRQOL, and parents' own HRQOL. RESULTS: Child interviews generated 18 topics. Worry (10 of 24 patients [42%]) was most frequently mentioned. Parent interviews generated 22 topics regarding their children's HRQOL. The most frequently mentioned topic was comments from others (15 of 24 patients [63%]). Regarding the parents' own HRQOL, 14 topics were identified; the most frequently mentioned was worry regarding possible surgery (15 of 24 patients [63%]). CONCLUSIONS: Multiple individual interviews revealed specific HRQOL concerns, such as worry, in children with IXT and their parents. We will use the concerns identified to develop condition-specific HRQOL instruments for IXT.

The effect of Bangerter filters on optotype acuity, Vernier acuity, and contrast sensitivity.

PURPOSE: Bangerter filters are designed to cause progressive degradation of distance optotype acuity to predicted levels (density label indicating expected decimal acuity) and are used to treat amblyopia and diplopia. Few authors have reported data regarding induced acuity deficits. We investigated the effect of Bangerter filters on distance and near optotype acuity, vernier acuity, and contrast sensitivity. METHODS: Fifteen subjects with best-corrected optotype acuity of at least 20/25 in each eye were blurred sequentially in one eye with 7 Bangerter filters (densities <0.1, 0.1, 0.2, 0.3, 0.4, 0.8, and 1.0). At each filter level, distance and near optotype acuity (LogMAR), vernier acuity, and contrast sensitivity were assessed. Mean log acuities were compared using generalized estimating equation methods. RESULTS: The 1.0, 0.8, and 0.4 filters degraded distance optotype acuity to a similar degree (mean 0.22, 0.23, and 0.28 logMAR). Subsequent filters progressively degraded acuity: 0.44, 0.57, 0.93, and 1.69 logMAR. Near optotype acuity was reduced in a similar pattern. Vernier acuity was minimally degraded by 1.0, 0.8, and 0.4 filters (18, 19, and 20 arcsec), followed by progressive degradation with subsequent filters (31, 35, 113, and 387 arcsec). Contrast sensitivity was minimally reduced with filters 1.0 through 0.2 and then precipitously degraded with 0.1 and <0.1 filters. CONCLUSIONS: The 1.0, 0.8, and 0.4 filters cause similar, minimal degradation of distance and near optotype and vernier acuity, whereas subsequent filters cause progressive degradation. Contrast sensitivity is not markedly reduced until the 0.1 filter. These results have important implications for the use of Bangerter filters therapeutically.

Comparison of a diplopia questionnaire to the Goldmann diplopia field.

PURPOSE: To compare diplopia scores obtained with a new diplopia questionnaire to the established Goldmann diplopia field. METHODS: Seventy-five consecutive patients with binocular diplopia associated with any type of strabismus were assessed with the diplopia questionnaire and the Goldmann perimeter. Diplopia was scored, according to published protocols, from 0 to 100, where 0 is no diplopia and 100 is diplopia in all measured positions. Where there was a discrepancy of more than 20 points between the Goldmann diplopia field and the diplopia questionnaire, two observers classified the reasons for the discrepancy. RESULTS: There was fair overall agreement between the diplopia questionnaire and the Goldmann diplopia field, with 44 (59%) of 75 patients having agreement within 20 points (intraclass correlation coefficient 0.53, 95% CI 0.35-0.68). Of the 31 (41%) of 75 patients who had a discrepancy of more than 20 points, 13 (42%) of 31 exhibited a higher diplopia score with the diplopia questionnaire than the Goldmann perimeter, and 18 (58%) of 31 showed a higher diplopia score with the Goldmann diplopia field than the questionnaire. The most frequent reason for a higher diplopia questionnaire score was the proximal test distance of the Goldmann diplopia field (6 of 13 cases). The most frequent reason for a higher Goldmann diplopia field score appeared to be patient adaptation to diplopia (9 of 18 cases). CONCLUSIONS: The diplopia questionnaire may better represent binocular diplopia in everyday life than the Goldmann perimeter, capturing adaptation to diplopia, suppression, fragile fusion, and diplopia with distance fixation.

Improvement in distance stereoacuity following surgery for intermittent exotropia.

PURPOSE: To evaluate whether distance stereoacuity improves following surgery for intermittent exotropia using the Frisby Davis Distance (FD2) and Distance Randot stereotests. METHODS: Eighteen patients (median age, 24 years; range, 5 to 68 years) with intermittent exotropia were prospectively enrolled. Stereoacuity was measured pre- and 6 weeks postoperatively using the FD2 and Frisby near tests (real depth tests) and Preschool Randot and Distance Randot tests (polaroid vectographs). RESULTS: Distance stereoacuity measured with the FD2 improved from a median preoperative value of 80 to 40 arcsec postoperatively (p = 0.04) and stereoacuity measured with the Distance Randot improved from a median of nil to 200 arcsec (p = 0.06). In those that had subnormal stereoacuity preoperatively, there was even more marked improvement in distance stereoacuity (FD2 median nil vs 40 arcsec, p = 0.002; Distance Randot median nil vs 200 arcsec, p = 0.004). Near stereoacuity measured with Frisby and Preschool Randot remained unchanged pre- to postoperatively (median, 60 and 80 arcsec, respectively). CONCLUSIONS: There was improvement in distance stereoacuity measured with both the FD2 and the Distance Randot stereotests in patients who underwent surgery for intermittent exotropia. The FD2 and Distance Randot may be useful outcome measures in future clinical trials of interventions for intermittent exotropia.

Postoperative endophthalmitis caused by Sphingomonas paucimobilis.

We present a case in which a new organism, Sphingomonas paucimobilis, caused endophthalmitis after phacoemulsification in a 73-year-old woman. The case shows a recurrent acute endophthalmitis with complete resolution only after vitrectomy. This organism has not been described as a cause of endophthalmitis and was resistant to initial medical management. We also describe an interaction between this organism and a co-infective organism that may account for the unusual clinical course.

Do variations in the theatre team have an impact on the incidence of complications?

BACKGROUND: To examine whether variations in non-medical personnel influence the incidence of complications in a cataract theatre. METHODS: A retrospective Case-Control study was undertaken in a single-site, designated cataract theatre. Staffing variations within theatre were examined and the incidence of cataract complications was assessed. RESULTS: 100 complicated lists and 200 uncomplicated control lists were chosen. At least 7 nurses were present for every list. Mean experience of the nurses was 6.4 years for case lists and 6.5 years for control lists. Average scrub nurse experience in years was 7.6 years for complicated lists and 8.0 years for controls. 26% of complicated case lists were affected by unplanned leave and 17% in control lists. Odds ratio 1.7 (1.0 to 3.1) 95% CI. CONCLUSION: Unplanned leave can have a detrimental effect on the operating list. The impact of this may be modifiable with careful planning.