Binocular vision & strabismus quarterly最新文献

Purpose: To discuss the clinical relevance of the article with the same name by authors R.J. Fullard, R.P. Rutstein and D.A. Corliss.

Methods: The results of the authors are compared to clinical relevant aniseikonia values. Also, the (in)accuracy of the analysis is questioned.

Results: The authors used an aniseikonia test range (-3.5% to 3.5%) that for the most part will not give symptoms. The measurement results show deviations from the expected aniseikonia values in the order of 0.3%, which is not clinically significant. The repeatability values found (approximately 0.5%) are small enough for clinically useful aniseikonia management. More accurate results could have been obtained if the accuracy of the the size lenses would have been taken into account.

Conclusions: When considering the clinical relevance of the findings in the article, it becomes clear that the Aniseikonia Inspector is a useful (and only) tool for complete aniseikonia management.

Purpose: Depth perception is an important part of many everyday tasks such as driving, catching a ball, and threading a needle. Binocular cues such as horizontal retinal image disparity (HRID) are significant cues to depth and play an important role in overall depth perception. Stereoscopic threshold (stereoacuity) is directly proportional to the interpupillary distance (IPD). Therefore, decreasing the IPD would predictably decrease streoacuity. Tilting the head toward one shoulder or the other will decrease the horizontal separation between the eyes thereby decreasing the IPD. This results in a decrease in stereoacuity. Although this has been demonstrated mathematically it has yet to be shown to have clinical significance.

Methods: All subjects had normal vision, eye alignment, and ocular health. Stereoacuity was evaluated using the BVAT distance stereoacuity test with the subject's head upright as well as when tilted to the right and left at 10, 20 and 30 degrees. A digital potograph verified the head tilt and IPD. The median stereoacuity for each head position was analyzed using the Friedman Test and pair-wise comparisons were made between different head positions using the Paired T-Test.

Results: 77.2% (44/57) of subjects exhibited a decrese in stereoacuity of at least 15 arc-sec with head tilt. The median change in stereoacuity from the upright was 22.5 to 45 arc-sec for the 6 head tilt positions (P 0.001). Although statistically the decrease in stereoacuity was not linear with regard to head tilt, there was an almost linear correlation between increasing head tilt and decreasing stereoacuity.

Conclusions: Head tilt to either the left or right creates a relative decrease in interpupillary distance with regards to the horizontal plane. This effective decrease in IPD results in a decrease in a subject's stereoacuity. Additionally, the greater the head tilt, the greater the loss of stereoacuity. This information is useful in counseling individuals, especially those engaged in activities where stereoacuity is critical to performance, to make a special effort to maintain a straight head position.

Purpose: To compare the maximum vertical fusion amplitudes in vertical directions (response pattern by respective higher eye), to investigate for possible asymmetry.

Methods: Vertical fusion amplitude (VFA) was measured in one hundred normal adults with normal single binocular vision using a computer based device that produced a gradually increasing, but optically distant test distance, Vertical fusion amplitudes in the vertical left- over-right (L/R, elevation of the left eye above the right eye) pattern direction were compared to the vertical fusion amplitudes in the vertical right-over-left direction pattern(R/L).

Results: The mean VFA was 4.08 +/-1.01 prism diopters, with vertical fusion amplitudes of 4.40 +/-1.44 prism diopters in the L/R direction and 3.75 +/-1.19 prism diopters in the R/L direction. There was no association between ocular dominance and the direction of greater VFA. Asymmetry in the vertical fusion response was found, with 77/100 subjects showing greater than a 10% difference between the means of the L/R and R/L measurements. The group with asymmetry had 17% greater mean VFA than the symmetric group.

Conclusion: Normal adults frequently have asymmetric directional vertical fusion amplitudes. The asymmetry appears to be due to the contribution of the direction with the greater VFA, rather than the result of both alternatives. These results are intriguing and bear further investigation. Possible explanations my be asymmetry of orbital anatomy or functional asymmetry of either muscular or neuronal origin. They do not appear to be due to the relative ocular dominance. Inherent VFA asymmetry should therefore be considered in all forms of vergence testing in the vertical direction.

An 11 year old boy with nephropathic cystinosis developed moderate to severe bilateral optic disc edema two months after he received a deceased donor renal allograft. The bilateral optic disc edema was found to be a result of intracranial hypertension diagnosed by lumbar puncture. No etiology was found. He was treated with acetazolamide and his optic dis edema resolved over a period of eight months and did not recur after acetazolamide was discontinued. The mechanism of intracranial hypertension in patients with nephropathic cystinosis is not well understood, but may involve obstruction of cerebrospinal fluid outflow due to deposition of cystine crystals in arachnoid villi.

Introduction: Monocular elevation deficiency with a tight ipsilateral inferior rectus muscle and fixation preference for the contralateral eye is a well recognized entity in strabismus. Most descriptions of the condition, however, do not document oblique muscle forced duction testing in the contralateral eye. The purpose of this report is to raise awareness that monocular elevation deficiency can be associated with, and may be secondary to, a floppy (lax) superior oblique muscle tendon in the contralateral fixating eye.

Methods: Retrospective case series.

Results: All 4 patients were previously diagnosed with congenital monocular elevation deficiency. All had variable head tilt towards the hypotopic eye, pseudoptosis with mild elevation limitation in that eye, and bilateral fundus excyclotorsion. In addition to inferior rectus muscle restriction in the hypotropic eye, forced duction testing was significant for contralateral superior oblique muscle tendon laxity.

Conclusions: Fixation preference for the eye with lax superior oblique muscle tendon may have led to a tight inferior rectus muscle in the non preferred eye. However, a congenital association between tight inferior rectus muscle and a lax superior oblique muscle tendon in the other eye cannot be ruled out. Patients diagnosed with monocular elevation deficiency should have careful attention to forced duction testing of the contralateral superior oblique muscle tendon.

Background: In progressive esotropia associated with high myopia and axial elongation, eso-hypodeviation of the eyeball occurs due to ocular dislocation and often progresses to complete fixed esotropia in the terminal stage. We report a rare case of this condition in whom manual pushing of the eyeball temporarily moved the ocular dislocation back into the muscle cone. A normal eye position and ocular movement were obtained in subsequent strabismus surgery. To our knowledge, there has been no previous report of such a case. It is uncertain if medial rectus muscle recession should be performed simultaneously with combination of the muscle bellies of the superior and lateral rectus muscles in surgery for progressive esotropia caused by high myopia. We discuss this issue in the context of the current case.

Case report: The patient was a 60 year old woman with a chief complaint of severe eso-hypotropia of the left eye, for which requested treatment. Ophthalmologic findings include refractive indices of -5.15 D right eye and left eye -22.0 D respectively. The left eye position was severely eso-hypotropic and ocular movement was limited in all directions. However, the left eye became capable of abduction when the medial side of the eye was pushed manually by rubbing during attempted levoversion. During levoversion while the patient was pushing the eyeball, the dislocation was reduced on Computerized Tomography imaging. In surgery, left medial rectus muscle recession and combination of the muscle bellies of the left superior rectus muscle and the left lateral rectus muscle were performed. After surgery, the eye position was markedly corrected and the abduction limitation was improved.

Conclusion: We encountered a case of progressive esotropia caused by high myopia in which ocular dislocation could be temporarily reversed. In this disease, pushing of the eyeball (push test) can be used to determine whether dislocation ban be temporarily reversed. If this is possible, determination of the degree of abduction may be useful for selection of an appropriate surgical procedure.