Extraocular Muscle Surgery for Extorsion after Macular Translocation Surgery

Review: Binocular double vision in the presence of visual field loss

Binocular double vision in strabismus is marked by diplopia (seeing the same object in two different directions) and visual confusion (seeing two different objects in the same direction). In strabismus with full visual field, the diplopia coexists with visual confusion across most of the binocular field. With visual field loss, or with use of partial prism segments for field expansion, the two phenomena may be separable. This separability is the focus of this review and offers new insights into binocular function. We show that confusion is necessary but is not sufficient for field expansion. Diplopia plays no role in field expansion but is necessary for clinical testing of strabismus, making such testing difficult in field loss conditions with confusion without diplopia. The roles of the three-dimensional structure of the real world and the dynamic of eye movements within that structure are considered as well. Suppression of one eye's partial view under binocular vision that develops in early-onset (childhood) strabismus is assumed to be a sensory adaption to diplopia. This assumption can be tested using the separation of diplopia and confusion.

A method to decrease the frequency of unintentional slippage after vitrectomy for rhegmatogenous retinal detachment

PURPOSE

To investigate a method for preventing retinal slippage after standard vitrectomy for rhegmatogenous retinal detachment.

METHODS

Eighty six eyes with bullous rhegmatogenous retinal detachment underwent successful standard vitrectomy. Patients were divided into 2 groups. In Group 1, 44 patients started face-down positioning at approximately 10 minutes after the end of the surgery. In Group 2, 42 patients started face-down positioning immediately at the end of the surgery. Postoperative retinal slippage was determined by fundus autofluorescence at 1 month postoperatively. Statistical analysis examined several factors to determine the association between the start time of the face-down positioning and retinal slippage.

RESULTS

Retinal slippage occurred in 63.6% of Group 1 and in 24.0% of Group 2 patients. This difference was statistically significant (P = 0.004, Fisher's exact probability test). Both the extent of retinal slippage (P = 0.029) and the face-down position (P < 0.001) were significantly associated with the retinal slippage.

CONCLUSION

Earlier implementation of face-down positioning may prevent retinal slippage after surgery in eyes with rhegmatogenous retinal detachment treated by standard vitrectomy.

Torsional anomalous retinal correspondence effectively expands the visual field in hemianopia

PURPOSE

Exotropia in congenital homonymous hemianopia has been reported to provide field expansion that is more useful when accompanied with harmonious anomalous retinal correspondence (HARC). Torsional strabismus with HARC provides a similar functional advantage. In a subject with hemianopia demonstrating a field expansion consistent with torsion, we documented torsional strabismus and torsional HARC.

METHODS

Monocular visual fields under binocular fixation conditions were plotted using a custom dichoptic visual field perimeter. The dichoptic visual field was also modified to measure perceived visual directions under dissociated and associated conditions across the central 50° diameter field. The field expansion and retinal correspondence of a subject with torsional strabismus (along with exotropia and right hypertropia) with congenital homonymous hemianopia was compared with that of another exotropic subject with acquired homonymous hemianopia without torsion and to a control subject with minimal phoria. Torsional rotations of the eyes were calculated from fundus photographs and perimetry.

RESULTS

Torsional anomalous retinal correspondence documented in the subject with congenital homonymous hemianopia provided a functional binocular field expansion up to 18°. Normal retinal correspondence was mapped for the full 50° visual field in the control subject and for the seeing field of the acquired homonymous hemianopia subject, limiting the functional field expansion benefit.

CONCLUSIONS

Torsional strabismus with anomalous retinal correspondence, when occurring with homonymous hemianopia provides useful field expansion in the lower and upper fields. Dichoptic perimetry permits documentation of ocular alignment (lateral, vertical, and torsional) and perceived visual direction under binocular and monocular viewing conditions. Evaluating patients with congenital or early strabismus for HARC is useful when considering surgical correction, particularly in the presence of congenital homonymous hemianopia.

[Study of the optic nerve head-fovea angle with retinophotography in healthy patients]

PURPOSE

The measurement of ocular torsion remains complicated and delicate when using subjective methods of measurement. Objective measures are now accessible in daily practice. This study determined the standards for ocular torsion in healthy patients with fundus photographs.

MATERIALS AND METHODS

Prospective study on 150 patients divided into three different age groups: children (under 15 years); young adults (15-50 years); and adults (over 50 years). All patients included had a normal oculomotor examination and were close to emmetropia. The fundus photographs were taken using a standardized system. The results were analyzed with a graphic computer program and took into consideration reproducible anatomical models; a statistical study determined the thresholds of statistical significance.

RESULTS

The optic nerve head-fovea angle followed a Gaussian distribution (mean, 6.3; standard deviation, 3.4). The measure was reproducible in a single patient through different successive examinations. There was no variation of this angle between the patients of different ages. Furthermore, in 87% of the patients, the fovea had a projection between the center and the lower edge of the optic nerve head, indicating that these anatomical models are reliable in a clinical evaluation of torsion.

DISCUSSION

This study confirms the accuracy of the objective measurements of ocular torsion and validates the anatomical models proposed by the rare studies already published.

CONCLUSIONS

The era of systematic ophthalmic photography is opening new perspectives in diagnosis now that the range in healthy patients has been determined, necessary before the disease could be analyzed. This validation of reliable and simple anatomical models should make this method easy to use in clinical and daily practice.