Dynamic Mechanical Properties of Porcine Lacrimal Canaliculus

Congenital canaliculops with punctal agenesis: is there a possibility to establish patency?

Canaliculops is a non-inflammatory dilatation of the canaliculus which can be secondary to trauma, punctal agenesis, herpetic infections or chronic drug use. This condition can affect either canaliculi and has shown female preponderance. Treatment described so far has consisted of cyst marsupialization with no literature on the post-operative epiphora in these cases. We describe two cases of canaliculops with punctal agenesis where we have tried to establish lacrimal patency.

Punctal dilatation and non-incisional canalicular curettage in the management of infectious canaliculitis

OBJECTIVE

To describe the outcomes of punctal dilatation and non-incisional canalicular curettage in patients with infectious canaliculitis.

METHODS

A retrospective analysis of 53 canaliculi of 47 eyes of 46 consecutive patients diagnosed with canaliculitis was performed from November 2015 to December 2018. All patients were treated with punctal dilatation and a non-incisional canalicular curettage. Parameters studied include demographics, clinical presentation, microbiological analysis, management and treatment outcomes. The outcome measures were clinical resolution of canaliculitis and resolution of epiphora.

RESULTS

The mean age at presentation was 59.34 years with female preponderance (M:F = 19:28). Left eye was more affected (64%, n = 30) as compared to the right (36%, n = 17). Only one patient presented bilaterally. Lower canaliculus was most commonly involved (68%, n = 32). Six eyes showed involvement of both upper and lower canaliculus. Presenting symptoms include discharge (81%), swelling of the eyelids (64%), watering (55%), redness (51%) and pain (39%). Punctal dilatation and non-incisional canalicular curettage were performed using punctum dilator and a small chalazion scoop (1 mm Meyhoefer chalazion curette). Of the 53 involved canaliculi, 14 canaliculi of 14 eyes underwent a repeat curettage for complete resolution and 1 canaliculus underwent the same procedure thrice. The most common micro-organisms isolated were Streptococci species (28% cases). At a mean follow-up of 6.8 months, resolution of canaliculitis was achieved in all patients; however, epiphora persisted in two eyes (4%).

CONCLUSION

Non-incisional canalicular curettage is a minimally invasive technique with good preservation of the punctal and canalicular anatomy. It also facilitates good anatomical and functional outcomes in infectious canaliculitis.

A case report on complete cure of recurrent primary canaliculitis by 4-snip punctoplasty and canalicular curettage

RATIONALE

For the treatment of primary canaliculitis, 1,2,3-snip punctoplasty and canalicular curettage are commonly used; however, a recurrence rate of 6.6% to 22% has been reported. Herein, we describe a case of recurrent primary canaliculitis that was completely cured by 4-snip punctoplasty and canalicular curettage.

PATIENT CONCERNS

A 53-year-old woman was admitted to our hospital with chief complaints of epiphora, discharge, eyelid flare up, and swelling near the inferior lacrimal punctum in the left eye, which initially presented 6 months earlier.

DIAGNOSIS

Based on the aforementioned symptoms, the patient was initially diagnosed with bacterial conjunctivitis at a local ophthalmologic clinic and used antibiotic eye drops for 6 months. However, her symptoms did not improve and they worsened at 2 weeks prior to admission. She was subsequently diagnosed with chronic dacryocystitis and referred to our hospital for surgical treatment. Slit lamp examination results showed conjunctival congestion in the inner corner of the left eye, along with eyelid flare up, swelling near the inferior lacrimal punctum, and yellowish discharge and concretion from the lacrimal punctal orifice. Furthermore, punctal regurgitation was not observed in the lacrimal sac compression test. Thus, the patient was diagnosed with primary canaliculitis on the basis of her clinical symptoms and laboratory findings.

INTERVENTIONS

Based on the diagnosis of primary canaliculitis, 1-snip punctoplasty and canalicular curettage were performed, and the patient was prescribed oral antibiotics for 2 weeks together with topical antibiotics for 4 weeks. Overall, the patient's symptoms improved after surgery, but epiphora and yellowish discharge from the lacrimal punctal orifice developed again 2 months after surgery during outpatient follow-up. Based on the diagnosis of recurrent primary canaliculitis, 4-snip punctoplasty and canalicular curettage were performed, and the patient was prescribed oral antibiotics for 2 weeks together with topical antibiotics for 4 weeks.

OUTCOMES

Over a 6-month follow-up period, the symptoms disappeared completely and no other findings were observed.

LESSONS

Four-snip punctoplasty and canalicular curettage are simple clinical procedures that can minimize the recurrence rate of primary canaliculitis. Hence, 4-snip punctoplasty and canalicular curettage should be considered as the 1st-line treatment for primary canaliculitis and recurrent cases.

Standardized static and dynamic evaluation of myocardial tissue properties

INTRODUCTION

Quantifying the mechanical behaviors of soft biological tissues is of considerable research interest. However, validity and reproducibility between different researchers and apparatus is questionable. This study aims to quantify the mechanical properties of myocardium while investigating methodologies that can standardize biological tissue testing.

MATERIALS AND METHODS

Tensile testing was performed to obtain Young's modulus and a dynamic mechanical analysis (DMA) determined the viscoelastic properties. A frequency range of 0.5 Hz (30bpm) to 3.5 Hz (210bpm) was analyzed. For tensile testing three different preconditioning settings were tested: no load, 0.05 N preload, and a cyclic preload at 2.5% strain and 10 cycles. Samples were placed in saline and tested at 37 °C. Five ovine and five porcine hearts were tested.

RESULTS AND DISCUSSION

Cyclic loading results in the most consistent moduli values. The modulus of ovine/porcine tissue was mean = 0.05/.06 MPa, SD = 0.02/0.03 MPa. The storage/loss modulus varied from = 0.02/0.003 MPa at 0.5 Hz to 0.04/0.008 MPa at 3.5 Hz; Stiffness increases linearly from 400 to 800 N m^-1 with a tan delta around 0.175.

CONCLUSIONS

Static analysis of the mechanical properties of myocardial tissue confirms that; preconditioning is necessary for reproducibility, and DMA provides a platform for reproducible testing of soft biological tissues.

Mechanistic modeling of ophthalmic drug delivery to the anterior chamber by eye drops and contact lenses

Ophthalmic drug for the anterior chamber diseases are delivered into tears by either eye drops or by extended release devices placed in the eyes. The instilled drug exits the eye through various routes including tear drainage into the nose through the canaliculi and transport across various ocular membranes. Understanding the mechanisms relevant to each route can be useful in predicting the dependency of ocular bioavailability on various formulation parameters, such as drug concentration, salinity, viscosity, etc. Mathematical modeling has been developed for each of the routes and validated by comparison with experiments. The individual models can be combined into a system model to predict the fraction of the instilled drug that reaches the target. This review summarizes the individual models for the transport of drugs across the cornea and conjunctiva and the canaliculi tear drainage. It also summarizes the combined tear dynamics model that can predict the ocular bioavailability of drugs instilled as eye drops. The predictions from the individual models and the combined model are in good agreement with experimental data. Both experiments and models predict that the corneal bioavailability for drugs delivered through eye drops is less than 5% due to the small area of the cornea in comparison to the conjunctiva, and the rapid clearance of the instilled solution by tear drainage. A contact lens is a natural choice for delivering drugs to the cornea due to the placement of the contact in the immediate vicinity of the cornea. The drug released by the contact towards the cornea surface is trapped in the post lens tear film for extended duration of at least 30min allowing transport of a large portion into the cornea. The model predictions backed by in vivo animal and clinical data show that the bioavailability increases to about 50% with contact lenses. This realization has encouraged considerable research towards delivering ocular drugs by contact lenses. Commercial contacts are, however, not ideal for drug delivery due to the short release durations which may necessitate wearing multiple lenses each day, reducing the viability of this approach. Recent research has focused on designing contacts that retain all critical properties while increasing the release durations to a few hours or a few days. Beagle dog studies with contact lenses containing vitamin E nanobarriers to attenuate drug transport have shown promising results. Human studies using contacts for drug delivery have also been conducted for allergy therapy but drug eluting contacts are not available in the market for any therapy.

Incision-sparing management of canaliculitis

PURPOSE

To report our results of canaliculitis treatment with our incision-sparing technique which includes dilation of the punctum and compression of the canaliculus to express the sulphur granules, curettage and irrigation of the canaliculus with antibiotic solutions, and topical antibiotic use.

METHODS

The medical records of all patients treated for canaliculitis between October 2009 and March 2013 were rewiewed. The punctum of affected canaliculus was dilated under local anesthesia. Then, starting just distal to common canaliculus, the horizontal canaliculus was compressed along its entire length using either a forceps or a cotton tip applicator on the conjunctival surface and a curette on the skin. Compression was repeated until no more sulphur granules appeared and the swelling of the canaliculus disappeared. A chalazion curette was inserted into canaliculus to evacuate any residual concretions. The canaliculus were irrigated with antibiotic solutions and the patients were prescribed topical antibiotic solutions for one month Patients with follow-up less than 3 months after the intervention were excluded from the study.

RESULTS

Nine patients met criteria for canaliculitis. There were 1 male and 8 female patients. Median age of the patients was 53 years (range 36-72 years). All patients had unilateral lower canaliculitis. Mean duration of the symptoms was 13.4 months (range 4-36 months). We followed up all patients for at least 3 months after the intervention. The signs and symptoms resolved completely in all patients within 1 month and recurrence was not observed in any patient. No patients reported epiphora after the procedure.

CONCLUSION

Our incision-sparing technique is effective in the treatment of canaliculitis. We suggest that minimally invasive or incision-sparing techniques be attempted before canaliculotomy to decrease postoperative complications rates.

Effect of viscosity on tear drainage and ocular residence time

PURPOSE

An increase in residence time of dry eye medications including artificial tears will likely enhance therapeutic benefits. The drainage rates and the residence time of eye drops depend on the viscosity of the instilled fluids. However, a quantitative understanding of the dependence of drainage rates and the residence time on viscosity is lacking. The current study aims to develop a mathematical model for the drainage of Newtonian fluids and also for power-law non-Newtonian fluids of different viscosities.

METHODS

This study is an extension of our previous study on the mathematical model of tear drainage. The tear drainage model is modified to describe the drainage of Newtonian fluids with viscosities higher than the tear viscosity and power-law non-Newtonian fluids with rheological parameters obtained from fitting experimental data in literature. The drainage rate through canaliculi was derived from the modified drainage model and was incorporated into a tear mass balance to calculate the transients of total solute quantity in ocular fluids and the bioavailability of instilled drugs.

RESULTS

For Newtonian fluids, increasing the viscosity does not affect the drainage rate unless the viscosity exceeds a critical value of about 4.4 cp. The viscosity has a maximum impact on drainage rate around a value of about 100 cp. The trends are similar for shear thinning power law fluids. The transients of total solute quantity, and the residence time agrees at least qualitatively with experimental studies.

CONCLUSIONS

A mathematical model has been developed for the drainage of Newtonian fluids and power-law fluids through canaliculi. The model can quantitatively explain different experimental observations on the effect of viscosity on the residence of instilled fluids on the ocular surface. The current study is helpful for understanding the mechanism of fluid drainage from the ocular surface and for improving the design of dry eye treatments.