The Success of Unilateral Surgery for Constant and Intermittent Exotropia and Factors Affecting It in a Large Scandinavian Case Series.

PURPOSE: To compare the results of surgery for constant and intermittent exotropia, to determine factors affecting surgical success, and to evaluate the effect of horizontal rectus muscle surgery on distance-near incomitance. METHODS: In this retrospective study of 291 Scandinavian patients, inclusion criteria were surgery for constant (n = 101) or intermittent (n = 190) exotropia with no vertical deviation, no previous strabismus surgery, and available postoperative follow-up data. Medical records of patients (age: 3 to 85 years) undergoing surgery were reviewed. Surgical success was defined as postoperative esodeviation of less than 5 prism diopters (PD) to exodeviation of 10 PD or less. RESULTS: Surgical success was 70% in constant exotropia and 80% in intermittent exotropia (P > .05). At follow-up 1.5 years after surgery, a significant drift was found in intermittent exotropia (P < .05). Different surgeons, spherical equivalents, anisometropia, amblyopia, gender, and age had no effect on surgical success (P > .05). The surgical success rate increased with decreasing preoperative angle (P < .05). Resection of the medial rectus muscle had a greater effect on the near deviation, whereas recession of the lateral rectus muscle had a greater effect on the distance deviation (P < .05). CONCLUSIONS: Surgical success was equally good in constant and intermittent exotropia, but better long-term stability was observed following surgery for constant exotropia. The only factor affecting surgical success was the preoperative deviation, with smaller deviations having a better outcome. A distance-near incomitance may be an important consideration in choosing the magnitude of medial versus lateral rectus muscle surgery. [J Pediatr Ophthalmol Strabismus. 2021;58(1):34-41.].

The impact of vision screening in preschool children on visual function in the Swedish adult population.

BACKGROUND: Amblyopia is the most common monocular visual impairment in Scandinavia. A visual screening programme for preschool children was introduced in Sweden in the 1970s to reduce the prevalence of amblyopia. The purpose of this study was to investigate the impact of this visual screening programme in adult men recruited to the armed forces in Sweden. METHODS: The prevalence of amblyopia was compared in recruits born in 1956-1957 (n = 1500), before the introduction of the visual screening programme (unscreened), and those born in 1977-1979 (n = 2626), after the visual screening programme was introduced (screened). Amblyopia was defined as bilateral, if the bilateral best corrected visual acuity (BCVA) was <0.5 (20/40), and unilateral if there was a ≥2-line interocular difference and BCVA was <0.625 (20/32) in the worse eye. Subgroup analysis was performed on recruits with hyperopia, myopia and anisometropia. RESULTS: The prevalence of amblyopia was significantly lower after the introduction of the Swedish visual screening programme. Forty-seven (3.3%) of the unscreened and 23 (0.9%) of the screened recruits had unilateral amblyopia (p < 0.0001, OR = 0.26 (95%CI 0.16-0.43)). The risk for developing amblyopia was markedly reduced by screening in recruits with hyperopia (≥2D) (p < 0.0001 and OR 0.034 (95% CI 0.003-0.207)) and anisometropia (≥1.5D interocular difference) (p < 0.01 and OR 0.20 (95% CI 0.08-0.66)). Only a few recruits with myopia had amblyopia. CONCLUSIONS: The results demonstrate the value of the Swedish visual screening programme for preschool children in preventing amblyopia. Anisometropia or high hyperopic refractive errors can be identified by screening and corrected to prevent amblyopia.

Clinical evidence supporting the use of donor sclera as spacer material in complicated cases of strabismus surgery - retrospective evaluation of surgical results in 117 patients with thyroid-associated ophthalmopathy or congenital strabismus.

PURPOSE: To examine the outcome of the use of donor sclera as spacer material in complicated cases of strabismus surgery. METHODS: A retrospective cohort study on patients with complicated thyroid-associated ophthalmopathy (TAO) (n = 42) or congenital strabismus (n = 75). Patients underwent strabismus surgery during 1994-2014. The surgical results were evaluated in terms of the reduction in the angle of deviation, the need for re-operation, complications and patient satisfaction. RESULTS: The majority of the TAO patients underwent surgery for vertical strabismus (n = 25). The vertical angle of deviation in the primary position was significantly reduced from a median of 23 prism dioptres (PD) to 2 PD (n = 35, p < 0.001). The horizontal angle of deviation in primary position for TAO patients with esotropia was significantly reduced, from a median of 35 PD to 2 PD (n = 17, p < 0.001). The majority of the congenital cases had horizontal strabismus (esotropia = 29, exotropia = 27). The angle of deviation in esotropia was reduced from a median of 29 PD to 8 PD (n = 36, p < 0.001) and in exotropia from 30 PD to 10 PD (n = 34, p < 0.001). Most of the patients were satisfied with the outcome of surgery, and only 12% required re-operation within 2 years. CONCLUSION: This is the first clinical study on the use of donor sclera as spacer material in complicated cases of strabismus surgery. The surgical results were good in terms of the reduction in the angle of deviation, the need for re-operation, complications and patient satisfaction, supporting the use of donor sclera for strabismus surgery.

Hypoperfusion following the injection of epinephrine in human forearm skin can be measured by RGB analysis but not with laser speckle contrast imaging.

BACKGROUND: The time taken for epinephrine to achieve its optimal effect during local anesthesia has recently become the subject of debate. The time from injection to commencement of surgery is traditionally quoted to be 7 to 10 min, while recent reports claim that it may take 30 min to achieve maximum hypoperfusion, which would prolong the time required for surgical procedures. The discrepancy may be related to difficulties associated with the techniques used to measure blood perfusion. The aim of this study was to test two methods of determining the time to maximum hypoperfusion. METHODS: Laser speckle contrast imaging (LSCI) and red, green, blue (RGB) analysis of images obtained with a commercial digital camera, were used to monitor the effect of infiltration with commonly used local anesthetic preparations: lidocaine (20 mg/ml) + epinephrine (12.5 µg/ml), lidocaine (10 mg/ml) + epinephrine (5 µg/ml), and lidocaine (20 mg/ml) alone, in healthy subjects. RESULTS: LSCI showed a paradoxical increase in signal after the injection of local anesthetics containing epinephrine, probably due to a change in the laser penetration depth resulting from blanching of the skin. However, RGB analysis of digital photographs gave more reliable results, showing skin blanching that corresponded to the expected effect of epinephrine in local anesthetics. The time to maximum effect was found to be 7 (range 5-10) minutes for 12.5 µg/ml epinephrine, and 9 (range 7-13) minutes for 5 µg/ml epinephrine in lidocaine. CONCLUSIONS: RGB analysis of digital images proved to be a valid technique for monitoring the effect of local anesthetics with epinephrine in human skin. The technique requires only a commercial digital camera and constitutes a cheap, simple method. The optimal delay between epinephrine injection and incision, to minimize bleeding, was found to be 7 to 9 min, which is in good agreement with common surgical practice.

Comparison of a new digital KM screen test with conventional Hess and Lees screen tests in the mapping of ocular deviations.

PURPOSE: To evaluate the digital KM screen computerized ocular motility test and to compare it with conventional nondigital techniques using the Hess and Lees screens. METHODS: Patients with known ocular deviations and a visual acuity of at least 20/100 underwent testing using the digital KM screen and the Hess and Lees screen tests. The examination duration, the subjectively perceived difficulty, and the patient's method of choice were compared for the three tests. The accuracy of test results was compared using Bland-Altman plots between testing methods. RESULTS: A total of 19 patients were included. Examination with the digital KM screen test was less time-consuming than tests with the Hess and Lees screens (P < 0.001 and P = 0.003, resp., compared with the digital KM screen). Patients found the test with the digital KM screen easier to perform than the Lees screen test (P = 0.009) but of similar difficulty to the Hess screen test (P = 0.203). The majority of the patients (83%) preferred the digital KM screen test to both of the other screen methods (P = 0.008). Bland-Altman plots showed that the results obtained with all three tests were similar. CONCLUSIONS: The digital KM screen is accurate and time saving and provides similar results to Lees and Hess screen testing. It also has the advantage of a digital data analysis and registration.

A novel surgical technique employing donor sclera in strabismus surgery.

We describe a novel surgical technique employing donor sclera as a spacer to solve the problem encountered in complicated cases of restrictive strabismus surgery when no more muscle or tendon is available for surgical extension of the eye muscle to correct the angle of deviation. This is often the case in patients who have previously undergone extensive surgery and in patients with mechanical restrictions, such as thyroid-associated orbitopathy (TAO).

Insulin aspart pharmacokinetics: an assessment of its variability and underlying mechanisms.

BACKGROUND: Insulin aspart (IAsp) is used by many diabetics as a meal-time insulin to control post-prandial glucose levels. As is the case with many other insulin types, the pharmacokinetics (PK), and consequently the pharmacodynamics (PD), is associated with clinical variability, both between and within individuals. The present article identifies the main physiological mechanisms that govern the PK of IAsp following subcutaneous administration and quantifies them in terms of their contribution to the overall variability. MATERIAL AND METHODS: CT scanning data from Thomsen et al. (2012) are used to investigate and quantify the properties of the subcutaneous depot. Data from Brange et al. (1990) are used to determine the effects of insulin chemistry in subcutis on the absorption rate. Intravenous (i.v.) bolus and infusion PK data for human insulin are used to understand and quantify the systemic distribution and elimination (Pørksen et al., 1997; Sjöstrand et al., 2002). PK and PD profiles for type 1 diabetics from Chen et al. (2005) are analyzed to demonstrate the effects of IAsp antibodies in terms of bound and unbound insulin. PK profiles from Thorisdottir et al. (2009) and Ma et al. (2012b) are analyzed in the nonlinear mixed effects software Monolix® to determine the presence and effects of the mechanisms described in this article. RESULTS: The distribution of IAsp in the subcutaneous depot show an initial dilution of approximately a factor of two in a single experiment. Injected insulin hexamers exist in a chemical equilibrium with monomers and dimers, which depends strongly on the degree of dilution in subcutis, the presence of auxiliary substances, and a variety of other factors. Sensitivity to the initial dilution in subcutis can thus be a cause of some of the variability. Temporal variations in the PK are explained by variations in the subcutaneous blood flow. IAsp antibodies are found to be a large contributor to the variability of total insulin PK in a study by Chen et al. (2005), since only the free fraction is eliminated via the receptors. The contribution of these and other sources of variability to the total variability is quantified via a population PK analysis and two recent clinical studies (Thorisdottir et al., 2009; Ma et al., 2012b), which support the presence and significance of the identified mechanisms. CONCLUSIONS: IAsp antibody binding, oligomeric transitions in subcutis, and blood flow dependent variations in absorption rate seem to dominate the PK variability of IAsp. It may be possible via e.g. formulation design to reduce some of these variability factors.

A comparison of pharmacokinetics and pharmacodynamics of biphasic insulin aspart 30, 50, 70 and pure insulin aspart: a randomized, quadruple crossover study.

The purpose of this study was to evaluate pharmacokinetic and pharmacodynamic profiles of pure insulin aspart and three different formulations of insulin aspart and protaminated insulin aspart: biphasic insulin aspart 30 (BIAsp30), biphasic insulin aspart 50 (BIAsp50) and biphasic insulin aspart 70 (BIAsp70). Nineteen type 1 diabetes patients received individually identical doses of the four different insulin aspart preparations on 4 separate days in this randomized crossover study. Having achieved overnight stable blood glucose control by intravenous infusions of human insulin, one of the trial insulins was injected subcutaneously and a standard meal was given in the morning. Plasma glucose and serum insulin aspart were recorded the following 12 hr. During the first 4 hr after injection with the trial insulin, the area under the curve for levels of insulin aspart (AUC(ins)) was significantly higher during insulin aspart treatment as compared to the other three insulin treatments, followed by BIAsp70, BIAsp50 and BIAsp30 (P < 0.05). Over the last 4 hr, the AUC(ins) for BIAsp30 was significantly higher as compared to the other insulin preparations (P < 0.05). By contrast, during the initial 4 hr, the area under the curve for levels of glucose (AUC(glu)) was highest after injection with BIAsp30 compared to the other three treatments (P < 0.05), while during the last 4 hr the highest AUC(glu) was seen following insulin aspart (P < 0.05). We conclude that when insulin aspart is pure or formulated with protamine in three different ratios, the pharmacokinetic profiles are readily distinguishable. These differences in pharmacokinetics are reflected in the pharmacodynamic profiles.