Primary Gaze Position Research Articles

How to improve ZMC fracture reconstruction due to severe enophthalmos

Introduction and importanceZygomaticomaxillary (ZMC) fractures are common, often resulting from traffic accidents, and account for 17 % of facial fractures. These fractures can lead to issues such as enophthalmos, flattened cheeks, diplopia, maxillary hypoesthesia. If the reduction is inadequate to restore facial structure, long term-functional and aesthetic complications may arise. In such cases a computed tomography (CT) scan with 3-dimensional (3D) reconstruction is valuable to assessing the fracture and planning surgery, with current technological advancements, 3D printing can now be utilised for this purpose. Presentation of caseA 24-year-old male, after a motorcycle accident and initial surgery for maxillofacial fractures, experienced persistent diplopia and facial numbness. Physical examination showed malpositioning of the right eye, and a CT scan with 3D reconstruction revealed multiple fractures and prior internal fixation. A 3D-printed model was created to plan a second surgery using rib cartilage and a silicone orbital base for orbital rim reconstruction. Post-surgery, the patient reported minimal pain and no diplopia or blurred vision in the primary gaze position. Clinical discussions3D printing is beneficial in facial reconstruction, aiding in surgical planning by allowing precise measurement and design of graft. Rib cartilage can serve as an alternative for orbital rim reconstruction, and 3D printing facilitates accurate harvesting of the rib. ConclusionIn cases of severe ZMC fracture, 3D printing was utilised as a guide during surgical preparation to achieve improved outcomes.

Factors Associated with Retinal Microvasculature Dropout Induced by Elevation of Intraocular Pressure in Primary Open-Angle Glaucoma.

To investigate the risk factors related to decrease in vessel density (VD) observed in primary open-angle glaucoma (POAG), due to acute increase in intraocular pressure (IOP) by an ophthalmodynamometer (OPD). This cross-sectional study involved 42 eyes of participants (22 Controls and 20 POAG patients) that underwent optical coherence tomography angiography (OCT-A) to assess VD in the peripapillary region in three examination sets: primary gaze position (1), 25-degree adduction (2) and 25-degree adduction with OPD compression (3). Individual relationships between IOP levels and changes in the superficial complex VD were evaluated after image processing and exclusion of large retinal vessels. Multivariable regression analysis was used to verify factors associated with differences in VD induced by IOP elevation. A significant increase in IOP was induced by OPD compression during adduction (mean ± SD, Control: + 13.8 ± 2.8; POAG: + 13.4 ± 2.1mmHg). Only during IOP elevation (set 3), a significant VD decrease was observed both in POAG eyes (p = 0.008) and controls (p = 0.022). Baseline IOP (p = 0.022), maximum IOP (p = 0.003), and scleral rigidity (p = 0.029) were significantly associated with VD decreases in eyes with POAG. No changes were observed in VD during adduction gaze exclusively. Acute IOP elevation induced with OPD, but not adduction gaze, decreased peripapillary VD measured with OCT-A imaging. IOP levels and scleral rigidity significantly affected VD reduction in POAG patients. Thus, high scleral rigidity may decrease the ability of the globe to dampen the well-known effects of IOP fluctuation on glaucoma onset and progression. What is known Decrease vascular density in the peripapillary retina was associated with POAG, but factors related to the vascular response to elevated IOP are unexplored. What is new OCT-A quantification shows decreases in vascular density of the superficial layers of the peripapillary retina during an acute elevation in IOP. High IOP levels and scleral rigidity significantly affected vascular density reduction in POAG patients.

Superior rectus/levator complex in acquired anophthalmic socket repaired with spheric implant-a computed tomography scan and topographic study.

To determine whether the levator palpebrae superioris (LPS)/superior rectus (SR) muscle complex, can influence the position of the upper lid and fornix in acquired anophthalmic sockets. This comparative non-randomized and non-interventional study included retrospective data of 21 patients with unilateral acquired anophthalmic sockets repaired with spheric implants. High-resolution computed tomography (CT) measurements of the LPM/SR muscle complex and clinical topographic position of the upper lid, superior and inferior fornix depth in primary gaze position were evaluated. Demographic data were presented as frequency and percentage proportions and quantitative variables comparing the socket measurements with the normal contralateral orbit was statistically analyzed using non-parametric tests considering P<0.05. The anophthalmic orbits had a significantly shorter LPS length (P=0.01) and significantly thicker SR (P=0.02) than the normal orbit. Lagophthalmos was present in anophthalmic sockets but not in normal orbits (P=0.002), while levator function was normal in both (P>0.05, all comparisons). The superior fornix depth was similar in the anophthalmic socket and the contralateral normal orbit (P=0.192) as well the inferior fornix depth (P=0.351). Acquired anophthalmic sockets repaired with spheric implants have shorter LPS, thicker SR, and more lagophthalmos than normal orbits. The relationship of the LPS and SR with other orbital structures, associated with passive or active forces acting in the final position of the lids and external ocular prosthesis should be further investigated.

Medial Rectus Disinsertion for the Management of Large-Angle Sensory Esotropia.

Background and Objectives: The aim of the report is to report the outcomes of the medial rectus (MR) disinsertion procedure for the management of large-angle esotropia (ET) patients. Materials and Methods: This is a retrospective case series of patients with large-angle ET who underwent an MR disinsertion procedure between March 2012 to April 2022. The procedure happened accidentally during muscle surgery. The demographic and clinical data, including sex, age, visual acuity, pre- and postoperative angle of strabismus, duction limitations, results of intraoperative forced duction tests, and follow-up duration were collected from medical records. Results: Five patients were enrolled in this study. The mean age was 62.2 ± 9.8 years, and the mean follow-up was 24.8 ± 8.7 months. The ET at the primary position of gaze was 92.0 ± 17.9 prism diopters (PD) before MR disinsertion and 38.0 ± 29.5 PD after MR disinsertion only. Abduction deficiency was -4 before after MR disinsertion, which improved to -1 at the last follow-up. Conclusions: The results of MR disinsertion were not as frustrating as anticipated. MR disinsertion may be considered in patients with large-angle sensory ET who refuse surgery on the opposite eye.

Clinical characteristics and associated features of pure orbital roof fractures: A ten-year retrospective review

PurposeTo present the demographics and clinical characteristics of pure (rim-sparing) orbital roof fractures. MethodsThis retrospective observational study used 10 years of data from a single institution. Patient age, sex, laterality, field of binocular single vision, associated injuries, and radiologic features were analyzed. Orbital roof fractures were categorized into four groups: comminuted/open, hinged, trapdoor, and linear. These were further subdivided into blow-in (-down) and blow-out (-up) fractures. Injury etiology was classified into fall, traffic accidents, sports injuries, assault, work-related, and others. ResultsData documented a low incidence rate of 2.5% (27 patients) in 1074 patients. Most patients were male (81%). The most common cause of injury was fall (48%), followed by traffic accidents (22%). Comminuted/open fractures constituted the bulk of fracture types (54%), followed by hinged, and linear fractures. Blow-in and blow-out fractures had an incidence rate of 50% each. Concomitant fractures of the medial and inferior orbital walls were predominant. Low surgical intervention was noted owing to acceptable field of binocular single vision outcomes, and the field of binocular single vision included the primary position of gaze in 88% of patients. ConclusionPure orbital roof fractures occurred in 2.5% of patients with pure orbital fractures. Patients were predominantly male with trauma caused by high energy forces, which regularly caused comminution of the roof and fractures of the medial and inferior orbital walls. Most patients were managed conservatively.

The role of surface electromyography in confirming the effect of blepharoplasty on strength of levator palpebrae superioris muscle in congenital blepharoptosis

BackgroundBlepharoptosis is an abnormal drooping of the upper eyelid margin with the eye in the primary gaze position. The clinical evaluating tests of upper eyelid muscle function lack objectivity, while surface electromyography (SEMG) is an objective evaluating tool of muscle power. We aimed to confirm the effect of blepharoplasty on levator muscle power after its shortening via levator aponeurosis resection surgery in cases of congenital ptosis through electrophysiological and clinical studies.The study included 40 patients aged ≥ 10 years with congenital blepharoptosis from the ophthalmology department of our university hospital, along with 40 age- and sex-matched healthy controls. All participants were subjected to clinical and electrophysiological assessment of levator muscle before and after blepharoplasty.ResultsThere was a significant improvement in clinical and electrophysiological findings among cases post-surgery compared with preoperative parameters. We recorded clinical improvement in 90% of patients postoperatively regarding eyelid morphology, symmetry, and visual field. Meanwhile, 82.5% of patients showed improvement in their muscle power using SEMG parameters in terms of improved muscle amplitude and firing characters compared with preoperative measures.ConclusionSEMG provides a standardized, objective method of analysis of upper eyelid muscle power. It confirms that levator muscle shortening via levator aponeurosis resection surgery could increase its power based on its pre-surgical power and electrophysiological characteristics; so, it could be considered an indicator of post-operative improvement of ptosis based on electrophysiological measurements before surgery. The relatively short follow-up period and lack of quantitative analysis of EMG were limitations of this study.

Thyroid Eye Disease and Rare Manifestations of Severe Restrictive Strabismus with Large Hypertropia: A Case Report and Treatment Considerations

Introduction : Restrictive strabismus with large hypertropia is an infrequent manifestation of thyroid eye disease that arises due to severe thickening of the superior rectus muscle. This condition can lead to losing the visual axis in the primary gaze position, and prompt management is essential.&#x0D; Case Illustration : A Forty-seven-year-old man came to the hospital and presented with misalignment in both eyes, known for five months before admission. Ophthalmology examination revealed visual acuity for both eyes was 0.4—Large hypertropia with 50 prism diopters and exotropia with 20 prism diopters, and down shoot restrictions were found in both eyes. The patient had a history of hyperthyroidism since eight months ago and regularly took PTU medication. CT scan of the orbit showed hypertrophy on the extraocular muscle.&#x0D; Discussion : Continued fibroblast stimulation results in collagen deposition and subsequent fibrosis, ultimately leading to restrictive strabismus in TED patients. For patients with large hypertropia, the primary surgical approach remains recession of the involved restricted muscles, with or without tendon elongation surgery. Vertical rectus muscle resection is preferred for its low inflammation and restriction risk, while hemi hang-back is another suitable option.&#x0D; Conclusion : The recession of restricted muscles and tendon elongation, preferably vertical rectus muscle resection, is necessary for patients with rare manifestations of restrictive strabismus and large hypertropia in thyroid eye disease.

Objective Diplopia Outcomes for Patients Treated With Teprotumumab for Thyroid Eye Disease.

Thyroid eye disease (TED) is a condition caused by inflammatory damage to the periocular tissue that often leads to double vision. Teprotumumab is an insulin-like growth factor 1 receptor antibody that was FDA approved for the management of TED in 2020, although much is yet to be elucidated regarding its effects on diplopia outcomes among patients with TED. Diplopia is a significant and life-altering effect of TED. Previous studies have reported the effect of teprotumumab on double vision subjectively using the Gorman diplopia score. However, there is a gap in the literature addressing the effect of teprotumumab treatment on objective ocular alignment measures. The purpose of our study was to address this gap. We performed a retrospective review of patients who were diagnosed with TED, presented with diplopia, and treated with teprotumumab in a single-center academic ophthalmology practice. The primary outcome was change in ocular alignment in primary gaze position at 6 months (completion of teprotumumab treatment). Secondary outcomes included change in ocular alignment in other gaze positions, proptosis, eyelid position, and clinical activity score (CAS) at 6 months compared with baseline. To determine what factors may predict ocular alignment response to teprotumumab, we analyzed baseline characteristics among 3 groups, divided based on whether ocular alignment was worsened, stable, or improved at 6 months. Seventeen patients met inclusion criteria, 3 (18%) worsened, 10 (59%) were stable, and 4 (24%) improved. CAS ( P = 0.02) was significantly different among the groups and was higher in those who worsened and those who improved compared with those who remained stable. Right gaze horizontal prism deviation ( P = 0.01) and left gaze horizontal prism deviation ( P = 0.03) were significantly different among the groups, with a greater degree of left gaze horizontal prism deviation in the worse group than the stable group ( P = 0.04). Our study demonstrated that most patients remained stable after teprotumumab treatment regarding ocular alignment in primary gaze and the number of patients who improved was slightly higher than the number of patients who worsened after teprotumumab treatment. There are some baseline measures, such as CAS and right and left gaze horizontal prism deviation that can help better predict how a patient will respond to teprotumumab treatment. Our results can better inform physicians of how to counsel patients with TED when considering teprotumumab therapy.

Real-time continuous EOG-based gaze angle estimation with baseline drift compensation under stationary head conditions

Objective:This work aims to propose a novel method to estimate the gaze from electrooculography (EOG) signals while compensating for the baseline drift, and which intrinsically detects fixations, saccades and blinks. In contrast to existing baseline drift mitigation techniques, the proposed framework is real-time-implementable, and does not require the average point of gaze to lie at the primary gaze position, nor does it disrupt the overall ocular pose-induced EOG signal DC characteristics. The EOG data used to validate the proposed method is also being made publicly available. Methods:The proposed method is based on the dual Kalman filter, which estimates the gaze angles (GAs) and the baseline concurrently, taking into consideration the EOG signal’s non-stationary and temporally-multimodal characteristics. In fact, it is a multiple-model technique based on a battery model of the eye wherein fixations, saccades and blinks are modelled separately. Results:When applied to short EOG data segments, a horizontal and vertical GA estimation error of 1.64 ± 0.82°and 1.97 ± 0.34°, respectively, was obtained, which compared well with the corresponding results obtained using the state-of-the-art linear regression models. Conversely, for longer data segments, the proposed framework yielded superior GA estimation performance when compared to the state-of-the-art techniques. Eye movement detection and labelling F-scores exceeding 90% were achieved. Conclusion:The proposed method yields reliable gaze estimation performance, and accurately detects fixations, saccades and blinks. Significance:This work proposes an integrated method to simultaneously estimate the GAs and address the baseline drift issue without the limitations of existing baseline drift mitigation techniques.

Lateral Tarsal Strip versus Tensor Fascia Lata Sling for Paralytic Ectropion: Comparison and Long-Term Outcomes.

Paralytic ectropion increases risk for corneal injury in facial palsy patients. Although a lateral tarsal strip (LTS) provides corneal coverage through superolateral lower eyelid pull, the unopposed lateral force may result in lateral displacement of the lower eyelid punctum and overall worsening asymmetry. A tensor fascia lata (TFL) lower eyelid sling may overcome some of these limitations. This study quantitatively compares scleral show, punctum deviation, lower marginal reflex distance, and periorbital symmetry between the two techniques. Retrospective review was performed on facial paralysis patients who underwent LTS or TFL sling surgery with no prior lower lid suspension procedures. Standardized preoperative and postoperative images in primary gaze position were used to measure scleral show and lower punctum deviation using ImageJ, and lower marginal reflex distance using Emotrics. Of 449 facial paralysis patients, 79 met inclusion criteria. Fifty-seven underwent LTS surgery and 22 underwent TFL sling surgery. Compared with preoperatively, lower medial scleral show improved significantly with both LTS (10.9 mm 2 ; P < 0.01) and TFL (14.7 mm 2 ; P < 0.01). The LTS group showed significant worsening of horizontal and vertical lower punctum deviation when compared with the TFL group (both P < 0.01). The LTS group was unable to achieve periorbital symmetry between the healthy and paralytic eye across all parameters measured postoperatively ( P < 0.01); and the TFL group achieved symmetry in medial scleral show, lateral scleral show, and lower punctum deviation. In patients with paralytic ectropion, TFL sling provides similar outcomes to LTS, with the added advantages of symmetry without lateralization or caudalization of the lower medial punctum. Therapeutic, III.

Head and facial anthropometry of the Indian population for designing a spectacle frame.

To establish the normative data of the head and face measurements needed to design an appropriate spectacle frame for the Indian population. Indian subjects between 20 and 40 years were included in the study. Thirteen parameters were measured using the direct and indirect methods using ImageJ software. Photographs of subjects were captured in the primary gaze position, with the head turned toward the subject's right and left by 90° from the primary gaze. The mean ± standard deviation of age was 27.6 ± 5.7; 55.38% were males. An independent t-test showed a significant difference in nose width (P = 0.001), inter-pupillary distance (P = 0.032), and body mass index (P = .012) between males and females. Inner inter-canthi distance (P = .265), outer inter-canthi distance (P = .509), and frontal angles (P = .536) showed no significant difference. There is a significant difference in face width compared with the other studies. The mean head width of males (154.168 ± 9.121) was wider than that of females (145.431 ± 8.923). This suggests a smaller distance between the temples of a spectacle frame for females. Considering the above factors, there is a need for a customized spectacle frame design providing better optics, improved cosmesis, and comfort to the wearer.

Monopolar and bipolar electrooculography signal characteristics due to target displacements—have we seen the whole picture?

The development of electrooculography (EOG)-based human-computer interface systems is generally based on the processing of the commonly referred to horizontal and vertical bipolar EOG channels, which are computed from a horizontally-aligned and another vertically-aligned pair of electrodes, respectively. Horizontal (vertical) target displacements are assumed to result in changes in the horizontal (vertical) EOG channel only, and any cross-talk between the bipolar channels is often neglected or incorrectly attributed solely to electrode misalignment with respect to the ocular rotation axes. Objective. The aim of this work is to demonstrate that such cross-talk is intrinsic to the geometric relationship between the orientation of the verging ocular globes and the planar displacement of the gaze target with respect to the primary gaze position. Approach. Since it is difficult to record actual EOG data with electrodes which are perfectly-aligned with the ocular rotation axes, this is studied by simulating the EOG potential values for various horizontally- and vertically-displacing targets using a dipole model of the eye. Main results. We show that cross-talk between the horizontal and vertical bipolar EOG channels is manifested even if the electrodes are aligned with the ocular rotation axes. Specifically, for a horizontally- (vertically-)displaced target, while the monopolar EOG signals obtained from the horizontally- (vertically-)aligned electrodes exhibit an expected predominant potential displacement, a smaller displacement is also exhibited in the monopolar EOG signals obtained from the vertically- (horizontally-)aligned electrodes. These unexpected displacements in the vertically- (horizontally-)aligned monopolar channels may have different magnitudes, resulting in an effective potential displacement in the vertical (horizontal) bipolar EOG channel. Significance. This is significant as it shows that, unlike in many works published so far for EOG-based ocular pose estimation, it is not sufficient to only use the horizontal (vertical) bipolar EOG channel to estimate the horizontal (vertical) displacement of the ocular pose.

THE EFFECT OF PALPEBRAL FISSURE HEIGHT IN PRIMARY GAZE POSITION ON TEAR FILM STABILITY.

This study aimed to investigate the effect of palpebral fissure height in primary gaze position in healthy individuals on tear film stability. In this cross-sectional study, 120 subjects (60 male and female each) were enrolled and divided according to age into two groups, i.e., group 1 (aged 18-50 years) and group 2 (aged 51 and older). Palpebral fissure height on both eyes was measured in primary gaze position with a clear plastic ruler held in a central vertical position between the upper and lower lid margin, and the standard tear break-up time (TBUT) test was performed to evaluate tear film stability. Palpebral fissure height was significantly higher in younger than older subjects in all measurements on both eyes (p<0.001), and TBUT was shorter in older than in younger subjects. In all subjects included in the study, palpebral fissure height was not related to TBUT (p=0.589). However, analyzing the two age groups separately, a significant negative correlation was found between the palpebral fissure height and TBUT in both groups of younger (p<0.001) and older (p=0.009) subjects. In conclusion, an enlarged exposed ocular surface due to higher palpebral fissure height in healthy individual's primary gaze position negatively affects tear film stability expressed by TBUT.

A-Scan Ultrasonographic Evaluation of Patients with Idiopathic Intracranial Hypertension: Comparison of Optic Nerves.

Background: To evaluate the interocular optic nerve diameter (ONDs) asymmetry in patients with idiopathic intracranial hypertension (IIH) utilizing the A-scan ultrasound technique. Methods: Thirty-seven patients diagnosed with IIH were recruited from outpatients referred to the University Eye Unit between June 2014 and December 2021. Patients with optic disc pseudoedema or edema caused by other conditions were excluded. All patients with negative neuroimaging for intracranial space-occupying masses underwent standardized A-scan measurement of the OND in the primary gaze and lateral position (30 degrees test). Results: Mean, median, standard deviation, the minimum and maximum value of the two eyes at 0 degrees and the difference between the left and right thicker and thinner ONDs were measured. The two-tailed paired student t-test between the two eyes was performed using SPSS software. A statistically significant difference (p-value <0.001) between the two eyes, without a side prevalence, was found. Conclusions: Due to the differences between the ONDs of both eyes, we propose to use the mean of the ONDs between the left and right eyes at 0 degrees with the standardized A-scan diagnostic technique for a better follow-up of patients with IIH.

Aesthetic Changes of Brow-Eyelid Continuum After Correction of Moderate-Severe Blepharoptosis with Conjoint Fascial Sheath Suspension.

As periorbital aesthetic commonly improved in blepharoptosis patients after correction surgery, the aim of this study was to elaborate the brow-eyelid continuum changes in moderate-severe ptosis patients who underwent conjoint fascial sheath suspension systematically. Patients with moderate-severe ptosis who underwent conjoint fascial sheath suspension were assessed by using pre- and post-operative digital photographs in the primary gaze position of the eye. The main outcome measurements included marginal reflex distance1 (MRD1), palpebral fissure height (PFH), eyebrow position, the symmetry of face and the horizontal forehead lines condition. There were 43 patients (53 eyelids) in our study, including 33 unilateral and 10 bilateral patients. The mean levator function was 3.00 ± 1.07mm. Before surgery, the mean MRD1 and PFH were 0.60 ± 1.14mm and 6.75 ± 1.71mm, respectively. The mean eyebrow height at medial, center, lateral position was 33.16 ± 3.95mm, 35.99 ± 4.02mm and 34.35 ± 4.80mm, respectively. It was found that MRD1 and PFH symmetry both were 23.26% and eyebrow symmetry was 62.79%. For forehead wrinkles, 48.84% of the patients was mild, 34.88% was moderate, and 16.28% was severe. The average follow-up was 12.78 months (ranged from 12 to 18months). One month after surgery, the mean MRD1 and PFH were 5.68 ± 0.86mm, 11.61 ± 0.97mm, respectively, both of which improved significantly (P < 0.0001). The mean eyebrow height at medial, center, lateral position descended to 28.22 ± 4.77mm (P = 0.017), 31.41 ± 4.58mm (P = 0.033) and 30.28 ± 3.41mm (P = 0.018), respectively. The result showed that the rate of patients with MRD1 symmetry was 32.56%, PFH symmetry was 30.23%, and eyebrow symmetry was 90.7%. For forehead wrinkles, 69.77% was mild and 30.23% was moderate. Then, patients' eyebrow gradually elevated, while their upper eyelid dropped. At the last follow-up, the mean MRD1 and PFH were 3.83 ± 0.98mm and 9.84 ± 1.56mm, respectively. The mean eyebrow height at medial, center, lateral position improved to 30.52 ± 4.59mm (P = 0.031), 32.40 ± 4.68mm (P = 0.033), 31.19 ± 4.16mm (P = 0.028), respectively. The patients with MRD1 symmetry accounted for 86.05%, PFH symmetry 86.05%, and eyebrow symmetry 90.7%. For forehead wrinkles, 67.44% was mild and 32.56% was moderate. CFS suspension can effectively reconstruct moderate-severe ptosis patients' aesthetics of the brow-eyelid continuum by descending elevated eyebrow, improving facial symmetry and reducing forehead rhytids. This journal requires that authors assign a level of evidence to each article. For a full description of these Evidence-Based Medicine ratings, please refer to the Table of Contents or the online Instructions to Authors www.springer.com/00266 .

Augmented lateral rectus muscle recession for treatment of infantile exotropia.

The surgical outcome is usually not satisfactory for treatment of primary infantile exotropia (PIE) with large exodeviation angels of more than 50 prism diopters (PD). Here, we evaluate the effectiveness of augmented bilateral lateral rectus muscle recession (ABLRR) in treatment of PIE with large deviation angles. A retrospective analysis was performed for 25 patients with PIE who underwent ABLRR. ABLRR was performed using a hemi-hang-back technique. Ocular alignment, ocular motility and binocular vision were evaluated pre- and postoperatively. Fourteen males and 11 females with PIE were included in this study, with a mean age of (3.92 ± 2.02) years (range, 1-7years). The average exodeviation angle was (-66.32 ± 7.84) PD (range, -60--80 PD) preoperatively. All patients underwent ABLRR using the hemi-hang-back technique. Three of them underwent bilateral inferior oblique muscle anterior transposition in the same operation. The mean surgical dosage was (11.08 ± 1.19) mm for each lateral rectus muscle. The mean of deviation angel was -2.28 ± 5.08 PD postoperatively (P < 0.05). All patients did not have abduction deficiency after a large amount of lateral rectus recession. Twenty-one of 25 patients (84.0%) achieved orthophoria at the primary gaze position at the final visit, and 13 patients obtained binocular vision. ABLRR is an effective and safe surgical procedure for treatment of PIE with a large deviation angle.

Perception of Coherent Motion in Infantile Nystagmus Syndrome.

PurposeResearch on infantile nystagmus syndrome (INS) and motion perception is limited. We investigated how individuals with INS perform coherent motion tasks. Particularly, we assessed how the null position affects their performance.MethodsSubjects with INS and controls identified the direction of coherent motion stimuli (22 subjects with INS and 13 controls) in a two-alternative forced-choice design. For subjects with INS, testing was done at the null position and 15 degrees away from it. If there was no null, testing was done at primary gaze position and 15 degrees away from primary. For controls, testing was done at primary gaze position and 20 degrees away from primary. Horizontal and vertical motion coherence thresholds were determined.ResultsSubjects with INS showed significantly higher horizontal and vertical motion coherence thresholds compared with controls at both gaze positions (P < 0.001). Within the INS group, for 12 subjects with INS who had an identified null position, no differences in coherence thresholds were found between their null and 15 degrees away from it (P > 0.05).ConclusionsCoherent motion perception was impaired in subjects with INS. The null position did not significantly influence motion coherence thresholds for either horizontal or vertical motion.

TEMoD: Target-Enabled Model-Based De-Drifting of the EOG Signal Baseline using a Battery Model of the Eye.

The electrooculography (EOG) signal baseline is subject to drifting, and several different techniques to mitigate this drift have been proposed in the literature. Some of these techniques, however, disrupt the overall ocular pose-induced DC characteristics of the EOG signal and may also require the data to be zero-centred, which means that the average point of gaze (POG) has to lie at the primary gaze position. In this work, we propose an alternative baseline drift mitigation technique which may be used to de-drift EOG data collected through protocols where the subject gazes at known targets. Specifically, it uses the target gaze angles (GAs) in a battery model of the eye to estimate the ocular pose-induced component, which is then used for baseline drift estimation. This method retains the overall signal morphology and may be applied to non-zero-centred data. The performance of the proposed baseline drift mitigation technique is compared to that of five other techniques which are commonly used in the literature, with results showing the general superior performance of the proposed technique.

Возможности призматической коррекции при лечении врожденного горизонтального нистагма

Purpose. Analysis the effectiveness of prismatic correction in the treatment of congenital horizontal nystagmus. Material and methods. The study included 20 patients with congenital horizontal nystagmus. Depending on the type of nystagmus and compensatory mechanisms to reduce its amplitude, two groups were identified: 10 patients with pendular nystagmus and nystagmus blockage syndrome (mean age, M±sd, 5.8±1.9 years) and 10 patients with jerky nystagmus and abnormal head posture and a null zone (5.7±2.1 years). Fresnel prisms were used to select and prescribe prismatic correction. Patients were under dynamic control from 6 months to 2 years with an assessment of the results every 3 months. Results. During treatment (using prism correction), uncorrected visual acuity had a statistically significant increase of 1.8 and 1.5 times both in the first (p=0.004) and the second (p=0.001) group, respectively. A similar, and even more pronounced, change in visual acuity was observed for corrected visual acuity – in the first group it increased 3 times (p=0.001) and in the second group 2.2 times (p=0.001). Conclusion. Prismatic correction in pendular nystagmus and esotropia allows to simulate (eliminate) nystagmus blockage syndrome and, thereby, to improve the quality of vision of the patient. In its turn, prismatic correction in jerky nystagmus with abnormal head posture allows to move null zone into the primary position of gaze, increase visual acuity due to the optimal optical correction and improve the patient's quality of life. Key words: nystagmus blockage syndrome, convergence fusion, abnormal head posture, null zone, Fresnel prisms

Velocity Discrimination in Infantile Nystagmus Syndrome.

PurposeResearch on infantile nystagmus syndrome (INS) and velocity discrimination is limited, and no research has examined velocity discrimination in subjects with INS at their null position and away from it. This study aims to investigate how individuals with INS perform, compared with controls, when carrying out velocity discrimination tasks. Particularly, the study aims to assess how the null position affects their performance.MethodsINS subjects (N = 21, mean age 24 years; age range, 15–34 years) and controls (N = 16, mean age 26 years; age range, 22–39 years) performed horizontal and vertical velocity discrimination tasks at two gaze positions. Eighteen INS subjects were classified as idiopathic INS and three had associated visual disorders (two had oculocutaneous albinism, and one had congenital cataract). For INS subjects, testing was done at the null position and 15° away from it. If there was no null, testing was done at primary gaze position and 15° away from primary. For controls, testing was done at primary gaze position and 20° away from primary. Horizontal and vertical velocity discrimination thresholds were determined and analyzed.ResultsINS subjects showed significantly higher horizontal and vertical velocity discrimination thresholds compared with controls at both gaze positions (P < 0.001). Horizontal thresholds for INS subjects were elevated more than vertical thresholds (P < 0.0001) for INS subjects but not for controls. Within the INS group, 12 INS subjects who had an identified null position showed significantly lower horizontal and vertical thresholds at the null than at 15° away from it (P < 0.05).ConclusionsVelocity discrimination was impaired in INS subjects, with better performance at the null. These findings could assist in understanding how INS affects the daily activities of patients in tasks involving moving objects, and aid in developing new clinical visual function assessments for INS.