Use of preoperative assessment of positionally induced cyclotorsion: a video-oculographic study

Purpose: Positionally induced cyclotorsion could be an important factor concerning correction of astigmatism in refractive surgery. The method of binocular three dimensional infrared video-oculography (3D-VOG) was used to determine a possible influence of body position on cyclotorsion. Methods: 38 eyes (19 healthy subjects, median value of age 25.5) with normal binocular vision were examined using 3D-VOG. This method records ocular motions and positions of both eyes simultaneously in the x, y, and z axis. Cycloposition of the eyes was recorded first in a seated position (both eyes open, test 1), then in a supine position (right eye closed, test 2), occlusion of both eyes (test 3), both eyes open (test 4). Cyclovergence was calculated as the difference between the right and the left eye positions. Results: The range of cyclotorsion of the right and left eye in all four tests was between 1.13° excyclotorsion and 0.34° incyclotorsion. There was no statistically significant difference of the median values for torsion for the four test situations. Concerning the influence of body position on cyclotorsion, a statistically significant difference between the different test positions and settings did not exist. Median values for right/left torsion/cyclovergence were: 0.17/0.04/0.02 (test 1), −0.31/−0.71/−0.16 (test 2), −1.09/−0.60/0.82 (test 3), 0.28/0.28/−0.82 (test 4). Conclusions: Cyclotorsion does not significantly change between seated and supine position in subjects with normal binocular vision and stable fixation. In these subjects, an erroneous refractive surgery due to incorrect measurement of the axis of astigmatism in the seated position and performing the refractive surgery in the supine position, is very unlikely

Surgical treatment of myopic strabismus fixus: a graded approach

BACKGROUND: Surgical treatment of myopic strabismus fixus is challenging. Options for its correction range from conventional combined recession-resection surgery to innovative surgical procedures aiming to correct the deviated muscle paths. In this report we review our experience and compare the results of various surgical options for treatment of strabismus fixus. METHODS: We report the surgical outcomes of nine adults with acquired strabismus fixus due to myopia with a follow-up of 1 year. Patients were enrolled between May 2003 and April 2007 in this retrospective study. The surgical procedure was determined depending on the angle of deviation and extent of motility impairment. A new transposition technique was performed in one patient who had an extreme variant of strabismus fixus. RESULTS: Combined recession-resection surgery was performed in four patients with resulting small-angle esotropia. In patients with both esotropia and hypotropia due to muscle alignment, we performed an additional upward displacement of both horizontal recti muscles combined with a myopexy of the lateral rectus muscle. The results were satisfying; in particular in one patient who had a transposition procedure a significant improvement was achieved. CONCLUSIONS: For treatment of myopic strabismus fixus, a graded approach seems advisable. Combined recession-resection surgery yields good results for smaller deviations with mildly impaired motility, additional fixation techniques need to be applied once the horizontal muscle paths are deviated, and in extreme cases, a transposition procedure is required

Angiopoietin-2 causes pericyte dropout in the normal retina: evidence for involvement in diabetic retinopathy

Pericyte loss is an early pathologic feature of diabetic retinopathy, consistently present in retinae of diabetic humans and animals. Because pericyte recruitment and endothelial cell survival are controlled, in part, by the angiopoietin/Tie2 ligand/receptor system, we studied the expression of angiopoietin-2 and -1 in relation to the evolution of pericyte loss in diabetic rat retinae, using quantitative retinal morphometry, and in retinae from mice with heterozygous angiopoietin deficiency (Ang-2 LacZ knock-in mice). Finally, recombinant angiopoietin-2 was injected into eyes of nondiabetic rats, and pericyte numbers were quantitated in retinal capillaries. Angiopoietin-1 protein was present in the normal maturing retina and was upregulated 2.5-fold in diabetic retinae over 3 months of diabetes. In contrast, angiopoietin-2 protein was consistently upregulated more than 30-fold in the retinae of diabetic rats, preceding the onset of pericyte loss. Heterozygous angiopoietin-2 deficiency completely prevented diabetes-induced pericyte loss and reduced the number of acellular capillary segments. Injection of angiopoietin-2 into the eyes of normal rats induced a dose-dependent pericyte loss. These data show that upregulation of angiopoietin-2 plays a critical role in the loss of pericytes in the diabetic retina