Physiological utility of ultrasound biomicroscopy in the lacrimal drainage system

Novel Evidence Concerning Lacrimal Sac Movement Using Ultra-High-Frequency Ultrasound Examinations of Lacrimal Drainage Systems

PURPOSE

Current hypothesis regarding the mechanism of active tear drainage is based on studies performed ex vivo or under nonphysiological conditions. Novel ultra-high-frequency ultrasound has the advantage of generating images with superior resolution, enabling measurements of low flow in small vessels, and the tracking of tissue motion in real time. The purpose of this study was to investigate the lacrimal drainage system and active drainage using this modality.

METHODS

The upper lacrimal drainage system was investigated with 40-70 MHz ultrasound in 22 eyes in 13 patients. Irrigation confirmed a lacrimal obstruction in 10 eyes. Motion tracking was used to map movement of the lateral lacrimal sac wall and to measure flow when possible.

RESULTS

The anatomy of the upper lacrimal drainage system was mapped in vivo, including the proximal canaliculi, which have not previously been imaged. The lacrimal sac lumen is slit shaped in its resting state but is distended when irrigated or if a nasolacrimal duct obstruction is present. Thus, the healthy lacrimal sac is not a cavity, and the medial retinaculum does not act against a stretched structure. Motion tracking visualized the "lacrimal pump," showing that the direction of motion of the lateral lacrimal sac wall is mainly in the sagittal plane during blinking.

CONCLUSIONS

Ultra-high-frequency ultrasound allows detailed physiological monitoring of the upper lacrimal drainage system in vivo. Our findings suggest that current theories of active tear drainage need to be reappraised.

A systematic review of ultrasound biomicroscopy use in pediatric ophthalmology

Ultrasound biomicroscopy (UBM) is the only available option for noninvasive, high-resolution imaging of the intricate iridociliary complex, and for anterior segment imaging with corneal haze or opacity. While these unique features render UBM essential for specific types of trauma, congenital anomalies, and anterior segment tumors, UBM imaging has found clinical utility in a broad spectrum of diseases for structural assessments not limited to the anterior intraocular anatomy, but also for eyelid and orbit anatomy. This imaging tool has a very specific niche in the pediatric population where anterior segment disease can be accompanied by corneal opacity or clouding, and anomalies posterior to the iris may be present. Pediatric patients present additional diagnostic challenges. They are often unable to offer detailed histories or fully cooperate with examination, thus amplifying the need for high-resolution imaging. This purpose of this systematic review is to identify and synthesize the body of literature involving use of UBM to describe, evaluate, diagnose, or optimize treatment of pediatric ocular disease. The collated peer-reviewed research details the utility of this imaging modality, clarifies the structures and diseases most relevant for this tool, and describes quantitative and qualitative features of UBM imaging among pediatric subjects. This summary will include information about the specific applications available to enhance clinical care for pediatric eye disease.

Value of ultrasound biomicroscopy in assessment of small masses at medial canthal region

PURPOSE

Conventional imaging techniques are not sensitive enough to reveal detailed structures of lacrimal drainage system (LDS) and its surrounding tissue (ST). Our study aimed to explore utility of ultrasound biomicroscopy (UBM) in assessment of small masses at the medial canthal region and compare performance of UBM with conventional imaging techniques.

METHODS

We prospectively recruited cases with small mass (long axis < 1 cm) at the medial canthal region (upper LDS-located area) from June 2017 to October 2018. UBM ± color Doppler flow imaging (CDFI) and conventional imaging techniques (computed tomography, magnetic resonance imaging, and dacryocystography) were conducted by four independent practitioners. Results were analyzed against gold standards with Cohen's kappa test in three aspects including LDS patency, mass location, and presumptive diagnosis. Corresponding gold standards were syringe and dacryocystography, intraoperative findings, and pathological/empirical diagnosis.

RESULTS

Seventy-two cases were recruited, including 20 cases of LDS lesions and 52 cases of ST lesions. Female (odds ratio 7.14) and age ≥ 37 (odds ratio 9.80) were risk factors for LDS lesion, and age range of 15-25 (odds ratio 9.17) was a risk factor for inflammatory ST lesion. In terms of LDS patency, UBM results were reliable for the detection of pre-saccal obstruction (kappa = 0.920), but were not reliable for intra-saccal and post-saccal obstruction (kappa = 0.106). In terms of mass location, the UBM (kappa = 0.766) performed better than conventional techniques (except for dacryocystography) to sort out ST lesions, with sensitivity of 93.8% and specificity of 83.3%. In terms of diagnosis, the UBM (kappa = 0.882) outweighed conventional techniques (except for magnetic resonance imaging) to distinguish cysts from nodules, with sensitivity of 93.8% and specificity of 94.4%. Notably, the UBM + CDFI achieved better performance than the UBM when screen out inflammatory lesions (kappa = 0.926 vs kappa = 0.689) and LDS-adjacent lesions (kappa = 0.815 vs kappa = 0.673), resulting in sensitivity of 91.7% and specificity of 100% for both testing items. If deep lesions (at the lacrimal sac-harbored area) were excluded, UBM reliability to detect inflammatory lesions (kappa = 0.915) and LDS-adjacent lesions (kappa = 0.770) improved, achieving sensitivity of 90.0% and 88.9%, and specificity of 100.0% and 92.7%, respectively.

CONCLUSIONS

The UBM is a valuable tool to assess superficial masses at the medial canthal region regarding pre-saccal obstruction, mass location, and presumptive diagnosis.

TRIAL REGISTRATION

This work was registered on Chinese Clinical Trial Registry website with registration number ChiCTR1800018956 .

Estimation of Eyelid Pressure Using a Blepharo-Tensiometer in Patients with Functional Nasolacrimal Duct Obstruction

Purpose

To compare the eyelid pressure between patients with functional nasolacrimal duct obstruction (FNLDO) and normal controls using blepharo-tensiometer, and to evaluate the relationship between eyelid pressure and the outcomes of silicone intubation (SI) in patients with FNLDO.

Study design

Prospective case-control study.

Methods

We enrolled 36 eyes of 36 patients with suspected FNLDO who underwent SI and 36 healthy eyes of age-matched controls. One eye of each patient with FNLDO was randomly selected for analysis. The eyelid pressure was estimated using a blepharo-tensiometer and compared between the control and FNLDO groups. The relationship between eyelid pressure and clinical variables was analyzed. The outcomes of SI were assessed at 6 months after surgery using subjective and objective criteria.

Results

The eyelid pressure was significantly lower in the FNLDO group than in the control group (P=0.008). In the control group, the eyelid pressure was correlated with age (P<0.001) and lower eyelid laxity (P=0.016). In the FNLDO group, the eyelid pressure was only correlated with age (P<0.001). The success rate of SI for FNLDO was 69.4% (25 of 36 eyes). The eyelid pressure was higher in the surgical success subgroup than in the failure subgroup, although the difference was not statistically significant (P=0.08).

Conclusions

Our results suggest that the eyelid pressure measured using a blepharo-tensiometer has a diagnostic value since it is decreased in patients with FNLDO. The role of eyelid pressure as a possible predictor of the outcomes of SI for FNLDO should be investigated in further studies. This trial is registered with KCT0002828.

Meibomian Gland Dysfunction in Cranial Nerve VII Palsy

PURPOSE

To examine clinical findings on meibomian gland dysfunction (MGD) in patients with unilateral cranial nerve VII (CN VII) palsy.

METHODS

This prospective observational study included 35 patients with unilateral CN VII palsy. The following features were compared between the affected and the unaffected sides: incidence of eyelid abnormalities (irregular eyelid margin, vascular engorgement, and plugged meibomian gland orifices), Marx line score, meibom expression score, area and density scores for corneal fluorescein staining, Schirmer test I (without topical anesthesia), and tear break-up time.

RESULTS

The affected side demonstrated significantly higher incidences of vascular engorgement (p = 0.004) and plugged meibomian gland orifices (p < 0.001) than the unaffected side. The incidence of an irregular eyelid margin was similar for both sides (p = 0.168). The scores for the Marx line (p < 0.001), meibom expression (p < 0.001), area (p = 0.034), and density (p = 0.026) were significantly higher for the affected side than for the unaffected side. The affected side showed a significantly higher Schirmer value than the unaffected side (p = 0.030). Tear break-up time was significantly shorter on the affected side than on the unaffected side (p = 0.023).

CONCLUSIONS

MGD was more markedly demonstrated on the affected side in patients with unilateral CN VII palsy.