Striated myogenesis and peristalsis in the fetal murine esophagus occur without cell migration or interstitial cells of Cajal.

Esophageal striated myogenesis progresses differently from appendicular myogenesis, but the mechanism underlying this process is incompletely understood. Early theories of transdifferentiation of smooth muscle into striated muscle are not supported by transgenic fate-mapping experiments; however, the origin of esophageal striated muscle remains unknown. To better define the process of striated myogenesis, we examined myogenesis in murine fetal cultured esophageal whole-organ explants. Embryonic day 14.5 (E14.5) esophagi maintained a functional contractile phenotype for up to 7 days in culture. Striated myogenesis, as evidenced by myogenin expression, proceeded in a craniocaudal direction along the length of the esophagus. Esophageal length did not change during this process. Complete, but not partial, mechanical disruption of the rostral esophagus inhibited myogenesis distally. Addition of fibroblast growth factor-2 (FGF-2) to the culture media failed to inhibit striated myogenesis, but attenuated smooth muscle actin expression and reduced peristaltic activity. Inhibition of c-kit failed to inhibit peristalsis. These results suggest that striated myogenic precursors are resident along the entire length of the esophagus by day 14.5 and do not migrate along the esophagus after E14.5. Induction of myogenesis craniocaudally appears to require physical continuity of the esophagus and is not inhibited by FGF-2. Finally, peristalsis in E14.5 esophagi appears not to be regulated by interstitial cells of Cajal.

Adjustable and non-adjustable strabismus surgery: a retrospective case-matched study.

Adjustable suture strabismus surgery was introduced to improve results in unpredictable strabismus cases. However, its usage is increasing and in some centres is routine. The present authors propose that the routine use of the adjustable suture technique can only be justified if it can be shown to confer an advantage to the patient. In a retrospective analysis of matched data, they compared the results of their adjustable with non-adjustable strabismus surgery. The adjustable suture procedures performed during a 5-year period, on non-thyroid eye disease patients, were matched to non-adjustable cases according to the type and aetiology of strabismus and the magnitude of deviation. Pairs were matched as closely as possible according to age and strabismus surgery history. All cases were incomitant. The surgical results of the two groups were analysed with regard to the pre-operative and post-operative angles of deviation, the post-operative drift, and a successful outcome, pre-defined by carefully selected criteria. Twenty-six cases were analysed in each of the two groups. Mean pre- and post-operative angles of deviation showed no significant difference between the two groups. 'Success' rates were 81% in the adjustable group and 88% in the non-adjustable group. Given that the success rate of the two techniques is similarly high, a much larger study is required to detect a difference in results, with statistical significance. The authors conclude that there is currently insufficient evidence that patients, without thyroid eye disease, benefit from the longer and potentially uncomfortable procedure of adjustable suture strabismus surgery to support its rapidly growing use and that a prospective randomised controlled trial is indicated.

The usefulness of Vistech and FACT contrast sensitivity charts for cataract and refractive surgery outcomes research.

AIM: To investigate the repeatability and sensitivity of two commonly used sine wave patch charts for contrast sensitivity (CS) measurement in cataract and refractive surgery outcomes. METHODS: The Vistech CS chart and its descendant, the Functional Acuity Contrast Test (FACT), were administered in three experiments: (1) Post-LASIK and age matched normal subjects; (2) Preoperative cataract surgery and age matched normal subjects; (3) Test-retest repeatability data in normal subjects. RESULTS: Contrast sensitivity was similar between post-LASIK and control groups and between the Vistech and FACT charts. The percentage of subjects one month post-LASIK achieving the maximum score across spatial frequencies (1.5, 3, 6, 12, 18 cycles per degree) were (50, 33, 13, 13, 0 respectively) for FACT, but only (0, 0, 13, 4, 0 respectively) for Vistech. A small number of cataract patients also registered the maximum score on the FACT, but up to 60% did not achieve the minimum score. Test-retest intraclass correlation coefficients varied from 0.28 to 0.64 for Vistech and 0.18 to 0.45 for FACT. Bland-Altman limits of agreement across spatial frequencies were between +/-0.30 and +/-0.85 logCS for Vistech, and +/-0.30 to +/-0.75 logCS for FACT. DISCUSSION: The Vistech was confirmed as providing poorly repeatable data. The FACT chart, likely because of a smaller step size, showed slightly better retest agreement. However, the reduced range of scores on the chart due to the smaller step size led to ceiling (post-LASIK) and floor (cataract) effects. These problems could mask subtle differences between groups of patients with near normal visual function as found post-refractive or cataract surgery. The Vistech and FACT CS charts are ill suited for refractive or cataract surgery outcomes research.

Use of pulse oximetry to monitor venous saturation during extracorporeal life support.

OBJECTIVE: To assess the ability of two different pulse oximeters to display continuous venous oxygen saturation through an extracorporeal bypass circuit with a degree of accuracy comparable to direct in-line oximetry. DESIGN: Prospective, comparison study of pulse oximeters (test oximeter 1 or test oximeter 2) and an in-line oximeter (test oximeter 3). SETTING: A tertiary care neonatal intensive care unit. PATIENTS: Sixty-five consecutive neonates with severe cardiorespiratory failure undergoing extracorporeal life support. INTERVENTIONS: The accuracy of the oximeters was determined by simultaneously comparing the saturation displayed by the pulse oximeters (test oximeters 1 and 2) and/or the in-line oximeter (test oximeter 3) with the measured fractional venous oxygen saturation obtained at regular intervals from the extracorporeal circuit. MAIN OUTCOME MEASURES: Venous oxygen saturation was the criterion standard used to determine accuracy. Bias was defined as the mean difference between observed pulse oximeter or in-line oximeter values and the measured venous oxygen saturation. Mean biases were calculated for venous oxygen saturation measurements between 55% and 99% at intervals of 10%. Precision (the standard deviation of the bias) was calculated for low (55% to 75%), medium (76% to 81%), and high (82% to 99%) venous oxygen saturation values. A total of 983 venous oxygen saturation measurements were made and compared with simultaneous oximeter readings from test oximeter 1 (n = 600), test oximeter 2 (n = 478), and test oximeter 3 (n = 587). RESULTS: Test oximeter 1 was the most precise instrument at each level of venous oxygen saturation (SD, 4.0 to 4.8). Test oximeter 3 demonstrated the most consistent mean bias (range, 8), but was the most inaccurate oximeter across all levels of venous oxygen saturation. CONCLUSIONS: In addition to its known clinical usefulness, pulse oximetry may serve as an adequate substitute for in-line oximetry during extracorporeal life support.

Secondary exotropia: a retrospective analysis of matched cases.

Secondary exotropia, that is exotropia following surgery for esotropia, remains frustratingly common, even among experienced strabismologists. In this study, we have compared a group of secondary exotropia cases with a matched group of cases of residual esotropia. Of the factors analyzed, only the presence of an A- or V-pattern preoperatively (P = .0077), the presence of limited postoperative adduction (P < .001), and postoperative binocular function (P = .0073) identified the secondary exotropes. The presence of reduced adduction postoperatively in subjects with secondary exotropia was a poor prognostic sign with 11 of the 13 cases requiring further surgery for poor cosmesis. The authors suggest two subclassifications of secondary exotropia.

Microsporidial keratoconjunctivitis in a patient with AIDS.

A male patient is described with acquired immune deficiency syndrome (AIDS) who developed chronic keratoconjunctivitis and chronic sinusitis due to infection with the microsporidian Encephalitozoon cuniculi. Diagnosis was confirmed by electron microscopic examination of conjunctival epithelial cells and nasal polypectomy specimens. Treatment with propamidine isethionate 0.1% (Brolene) eye drops six times daily led to a prompt resolution of the keratoconjunctivitis.

Preferential looking in the mentally handicapped.

We have assessed the feasibility of Preferential Looking (PL), using Teller Acuity Cards, for the estimation of binocular and monocular visual acuities in a group of mentally handicapped adults. Our results show the comparison between grating and recognition acuities, inter-observer variation, success rate, time taken and the sensitivity of this method in identifying monocular visual deficit in this group of subjects. The reasons for success or failure with PL methods in relation to criteria for mental handicap are discussed.

Preferential looking in clinical practice: a year's experience.

Preferential Looking (PL) is now a well established laboratory method of measuring visual acuity in preverbal children. We have evaluated the feasibility of its routine use in clinical practice. We present our methods and results obtained in 80 normal children and 36 children with visual disorder and discuss the problems encountered in applying this test.

The use of computerized contrast sensitivity, Arden gratings and low contrast letter charts in the assessment of amblyopia.

Contrast sensitivity measured with an electronic display was compared with Arden gratings and low contrast letter charts in normal and amblyopic children and adults. The low contrast letter charts and the Arden gratings used in the conventional manner revealed no additional information over that obtained by conventional Snellen acuity. However, the interocular differences found with each plate of the Arden gratings compared favourably with the computerized CSF. With the addition of an extra plate to test at a higher spatial frequency, the Arden gratings would be a useful technique for monitoring amblyopia therapy.

Assessment of vision in amblyopia.

This paper presents a brief review of clinical methods of assessment of vision in amblyopic infants and children. The problems encountered in this context include attention and motivation of the patient, and reliability and standardisation of method. Various solutions are examined and the relevance of the newer techniques of acuity estimation by preferential looking (PL), visual evoked cortical potentials (VECP) and psychophysical tests of contrast sensitivity is discussed.

Posterior capsulotomy and retinal detachment following extracapsular lens surgery.

A retrospective analysis of the results of extracapsular cataract surgery with and without implant is presented. Surgery was performed by a group of consultants and registrars from 1975 to 1982, and minimum patient follow-up was 12 months (mean 26.2 months). The incidence of postoperative capsulotomy was 14.3%, but the need for this procedure declines, becoming negligible after 3.5 years. Of 242 eligible eyes, aphakic retinal detachment occurred in only one.

Disciform macular degeneration in young adults.

We describe cases of haemorrhagic disciform macular detachment occurring in young adults in association with multifocal disease at the level of the retinal pigment epithelium (RPE). The cause of the original focal lesions is unknown. Our cases demonstrate a variable and unpredictable clinical course in which the disciform response may develop rapidly.

A device for automated laser delivery in retinal photocoagulation.

We report a modification to the argon-krypton laser (Lasertek Model AK 41) which allows optional automatic operation. This is a safe, time-saving device for use in cases requiring extensive retinal laser treatment.