Secondary Acquired Nasolacrimal Duct Obstruction as a Specific Complication of Treatment With Radioactive Iodine (Morphological Study).

PURPOSE: To conduct a morphological study of structural changes in the nasolacrimal duct in secondary acquired nasolacrimal duct obstruction (SALDO) as a result of treatment with radioiodine. METHODS: Twenty patients (20 cases) were involved: 10 cases with secondary acquired nasolacrimal duct obstruction at Hasner's valve level due to the treatment with radioiodine (group 1) and 10 cases with primary acquired nasolacrimal duct obstruction (group 2). During surgery, a biopsy of nasolacrimal duct tissue from Hasner's valve area was taken. A morphological study was performed using semi-fine sections technique. RESULTS: Patients of group 1 showed the following: desquamation of columnar epithelium, pinpoint ulceration of nasolacrimal duct wall, collapse of a significant part of the capillary bed, and absence of blood cells in their lumen. State of secretory cells of mucous glands varied from necrobiotic to the different stages of dystrophic, decreased lumens of acini with abundant microvesicles in cell cytoplasm were revealed. A specific sign noted in patients of group 2 was mixed inflammatory infiltration of the mucosa of the nasolacrimal duct. The picture corresponds to the exacerbation of a chronic inflammatory process. CONCLUSIONS: Changes revealed in patients of group 1 include desquamation of nasolacrimal duct epithelium, mucous gland lesion, and moderate fibrosis that indicate a probable primary character of the lesion. In patients of group 2, fibrotic changes were more significant and were due to a chronic inflammatory process. Thus, secondary acquired nasolacrimal duct obstruction after treatment with radioactive iodine has a specific pathogenesis and should be classified as a separate nosological form.

Microstructural changes in sclera under thermo-mechanical effect of 1.56 µm laser radiation increasing transscleral humor outflow.

BACKGROUND AND OBJECTIVES: Pores in the sclera are a candidate pathway for aqueous transport and therefore can be utilized to decrease the intraocular pressure (IOP) in glaucomatous eyes. Since pore formation is a well-known mechanism for stress relaxation in solids, laser-induced creation of pores in cartilage increases hydraulic permeability and promotes tissue regeneration. The aim of this paper is to demonstrate the thermo-mechanical effect of non-destructive laser irradiation on microstructural changes in sclera, in particular pore formation, resulting in substantial increase of water permeability of eye tissues that can be a novel approach to normalize the IOP. MATERIALS AND METHODS: Experiments were performed ex vivo on eight eyes of four mini-pigs and in vivo on eight eyes of four rabbits using pulse repetitive laser radiation of 1.56 µm in wavelength. Twenty laser spots of 0.6 mm in diameter with laser settings (power 0.9 W, pulse duration of 200 milliseconds, pulse repetition rate of 2 Hz) resulting in substantial increase of sclera hydraulic permeability were applied on the sclera at 1-2 mm from the eye limb. Sclera and underlying structures (choroid and ciliary body) of the rabbits' eyes were examined histologically in 1 and 45 days after laser irradiation, atomic force microscope (AFM) was applied before and after laser irradiation. RESULTS: Histological and AFM examinations have clearly recognized laser-assisted stable structural alterations: rarefication of the collagen structure in the laser irradiated zone and formation of sub-micron pores. Laser-induced alterations in the structure of ciliary bodies were small in size and mainly reversible. We have proposed a possible mechanism of the arising pores stabilization due to formation of small stable gas bubbles in sclera tissue. CONCLUSIONS: It is shown, for the first time, that thermo-mechanical effect of pulse repetitive laser irradiation results in pores formation in sclera. That can be a basis of a novel, safe, and effective technique for IOP normalization due to enhancing of uveoscleral outflow under non-destructive laser irradiation of the sclera.

Ocular surface changes in thyroid eye disease.

PURPOSE: To study the incidence and risk factors of ocular surface damage in thyroid eye disease (TED) and to determine histological changes underlying positive vital staining in this condition. METHODS: Forty-six patients (92 eyes) with TED were included in this study. Routine ophthalmologic examination, Schirmer test I, vital staining and corneal sensitivity were performed. Fifteen patients with positive vital staining underwent impression cytology and incisional biopsy. RESULTS: Positive vital staining with lissamine green was observed in 56 eyes (60.9%), 30 patients (65.2%). The average degree of staining was 4.57 ± 0.44 (National Eye Institute Workshop grading system). Severe dry eye syndrome was found in 16%. The following histological changes of conjunctiva were revealed: significant epithelial dystrophy with cell polymorphism, goblet cells loss, excessive desquamation and epithelial keratinization with local leukocytic infiltration of substantia propria. CONCLUSIONS: According to our results dry eye syndrome is present in 65.2% of patients (60.9% eyes) with TED. Significant risk factors of ocular surface damage in TED were exophthalmos, lagophthalmos, palpebral fissure height and lower lid retraction. Positive conjunctival staining results from punctuate epithelial erosions and excessive desquamation of superficial cells. Histopathologic changes detected in conjunctiva consistent with dry eye and are not specific for TED.

Revealing structural modifications in thermomechanical reshaping of collagenous tissues using optical coherence elastography.

Moderate heating of such collagenous tissues as cornea and cartilages by infra-red laser (IR laser) irradiation is an emerging technology for nondestructive modification of the tissue shape and microstructure for a variety of applications in ophthalmology, otolaryngology and so on. Postirradiation high-resolution microscopic examination indicates the appearance of microscopic either spheroidal or crack-like narrow pores depending on the tissue type and irradiation regime. Such examinations usually require special tissue preparation (eg, staining, drying that affect microstructure themselves) and are mostly suitable for studying individual pores, whereas evaluation of their averaged parameters, especially in situ, is challenging. Here, we demonstrate the ability of optical coherence tomography (OCT) to visualize areas of pore initiation and evaluate their averaged properties by combining visualization of residual irradiation-induced tissue dilatation and evaluation of the accompanying Young-modulus reduction by OCT-based compressional elastography. We show that the averaged OCT-based data obtained in situ fairly well agree with the microscopic examination results. The results obtained develop the basis for effective and safe applications of novel nondestructive laser technologies of tissue modification in clinical practice. PICTURE: Elastographic OCT-based images of an excised rabbit eye cornea subjected to thermomechanical laser-assisted reshaping. Central panel shows resultant cumulative dilatation in cornea after moderate (~45-50°C) pulse-periodic heating by an IR laser together with distribution of the inverse Young modulus 1/E before (left) and after (right) IR irradiation. Significant modulus decrease in the center of irradiated region is caused by initiated micropores. Their parameters can be extracted by analyzing the elastographic images.