Effects of lacrimal drainage occlusion with nondissolvable intracanalicular plugs on hydrogel contact lens wear.

PURPOSE: To investigate effects of lacrimal drainage occlusion with intracanalicular silicone plugs in hydrogel lens wearers with the symptom of dryness. Effects of rewetting drops in combination with the plugs were also evaluated. METHODS: A 6-week, prospective, double masked, placebo-controlled study design was followed. Thirty-five patients (26 females and 9 males) were entered into the study based on specific symptoms and signs of dry eye with hydrogel lens wear. Baseline symptoms, noninvasive prelens tear film break-up time, lens water content, fluorescein, and rose bengal staining were recorded. Herrick Lacrimal Plugs were inserted into both canaliculi of one previously randomized eye by an independent investigator. The fellow eye was manipulated in a sham procedure. Symptoms and signs were followed over 4 weeks. Nonpreserved rewetting drops were used in both eyes during the 5th week. Symptoms and signs were again followed. RESULTS: Symptoms improved more significantly in the plugged eye than the control eye after insertion of the plugs, and again after use of the drops. This improvement diminished in some of the patients. Prelens tear film break-up time was not significantly changed. Water content of all lenses combined increased only in the plugged eye with the use of drops. Fluorescein staining decreased significantly in the plugged eye. Rose bengal staining showed a slight decrease in the plugged eye. CONCLUSIONS: Intracanalicular silicone plugs offer improvement of symptoms and signs of dryness in this population. There seems to be some decrease in improvement of symptoms with the plugs over time. Concurrent use of rewetting drops increases the benefits.

Swelling of collagen intracanalicular implants.

BACKGROUND: Absorbable intracanalicular collagen implants are used to attempt to determine if permanent closure of the tear drainage system will diminish or alleviate the signs and symptoms of dryness. The rate of swelling of the collagen implants was measured in vitro in this study. METHODS: Collagen implants were submersed in saline, Refresh Plus artificial tears or Tobrex antibiotic solution on a hanging drop microscope slide. The diameter of the collagen rod was measured over time using videotaping and image processing. RESULTS: The 0.3- and 0.4-mm diameter collagen implants swelled approximately 55% to 65% in Unisol 4 Preservative Free saline and Refresh Plus artificial tear solution, with the majority of the swelling occurring over the first 30 minutes. The 0.4-mm diameter implants took slightly longer to reach the fully swollen state than did the 0.3-mm implants. They swelled somewhat less in Tobrex Ophthalmic Solution. CONCLUSIONS: Collagen implants swell approximately 60%, with the majority of the swelling occurring in the first 30 minutes. Thus, it will take approximately 30 minutes after insertion of the implants for the full occlusive effect to occur.

A synopsis of extended-wear lenses and lens care regimens.

The clinical properties of hydrogel and rigid gas-permeable contact lenses for extended wear are examined, with emphasis on oxygen permeability and transmissibility, so that clinicians may select lenses likely to minimize corneal edema or may predict the amount of edema likely with a given lens. Lens deposit formation and related problems are also described, as are lens care systems, particularly their limitations with respect to preventing infections. The advantages, disadvantages, and limitations of lens cleaners are discussed, and recommendations for use are provided.

One-week vs. 2-week hydrogel extended wear schedules.

Fifteen myopic patients wore 58% water content lenses for extended wear. The lens on one eye was removed weekly for 1 night and the lens on the other eye was removed only every 2 weeks. The patients were followed for 3 months. No significant difference in daytime corneal thickness was found between the two eyes at any visit. In comparing the corneal thickness the day before vs. the day after resuming lens wear, the mean thickness was no different for the 1-week schedule and tended to be slightly greater prior to removal for the 2-week schedule but not statistically different. There was no statistical difference in K-readings or corneal shape factor between the eyes. A mean increase in myopia was recorded, but it was only statistically significant for two visits for the 1-week wearing schedule eye. The number of positive biomicroscopic findings were slightly greater with the 2-week schedule. Two eyes developed corneal ulcers, one occurring on the 1-week schedule and one on the 2-week schedule.

Effect of some solutions on HGP contact lens parameters.

The effect of five common contact lens solutions on the overall diameter and base curve radii of PMMA, siloxane/acrylate and fluorosiloxane/acrylate lenses was studied. The alcohol containing cleaner, Miraflow, caused a significant swelling and base curve change of the siloxane/acrylate and fluorosiloxane/acrylate lenses with 30 minutes or longer soaking. Miraflow did not affect PMMA lenses. None of the other solutions tested affected any of the lenses tested.

Measured power distribution across the Bausch and Lomb Soflens (PAI) Bifocal.

The power distribution across Bausch and Lomb Soflens PAI Bifocal lenses was measured using a series of double aperture stops on a lensometer. The add power at different distances from the lens center is presented. A gradual increase in plus power approximately equivalent to an aspheric back surface of an eccentricity of 0.75 was found. The change in add with change in apical radius (lens distance power) is also reported. The measured change is compared to the calculated power change over the same radius range.

Critical base curve and diameter interval in the fitting of spherical soft contact lenses.

The effect of base curve and diameter variation on the fit or DuraSoft lenses was evaluated in terms of eight clinical fitting criteria: refraction, lens position, centering ability, stability of vision, amount and direction of movement, subjective comfort, and corneal physiological response. The minimum or critical intervals of base curve and diameter change necessary to produce significant changes in these criteria were determined. The results are discussed in relation to the design of diagnostic sets of lenses and the changes necessary to produce effective variations in clinical fit.

A comparison of different rigid contact lenses: edge thicknesses and contours.

The edge thickness and contour of rigid lenses is an important factor in lens comfort and acceptance. In this study the edges of two CAB lenses, a PMMA-silicone combination lens, a pure silicone lens had standard PMMA lenses are evaluated by molding the lenses. Considerable variation in thickness and contour of the peripheral portion of the lenses were found.

Clinical study of corneal response to the wear of low water content soft lenses.

The changes in central and peripheral corneal thickness and topography during initial (1st-day) wear, adaptation to, and long-term wear of the DuraSoft lens were monitored in a group of 10 patients. Monitoring was by means of the electronic digital pachometer and the photoelectronic keratoscope (PEK). A variety of physiological responses to lens wear was noted in individual patients, but generally the changes occurring were comparable to those reported for other soft lenses. These changes consisted of an average increase of 5-6% in central and peripheral corneal thickness during the initial phase of wear and 4-5% during adaptation; this was followed by a reduction with long-term wear to 2-3%. Corneal topography was relatively stable throughout the period of the study.

Inspection of back surface aspheric contact lenses.

Two methods of clinically inspecting and verifying rigid back surface aspheric contact lenses were investigated. A modification of the Radiuscope was found to be an accurate method for making such measurements. Measurement data of a number of aspheric lenses obtained by using this procedure are presented.

The United States Food and Drug Administration and the practice of optometry.

In the past decade the United States Food and Drug Administration has become increasingly involved with the regulation of materials used in the practice of optometry. It is the purpose of this paper to help the practitioner understand the FDA involvement, historically and legally, organization, how one can have input into the process, the procedures for testing and approving new drugs and devices, their regulation and the advantages and disadvantages of such control.

Soft lens cleaners: their effectiveness in removing depostis.

The useful life of a hydrophilic lens is often reduced by deposits forming on or within the polymeric structure of the lens. To eliminate this problem, several cleaning agents have been formulated to prevent and/or remove these deposits. The efficacy of these agents in cleaning heavily deposited lenses is the topic of this investigation.

Measured and laboratory-stated parameters of hydrophilic contact lenses.

One hundred thirty-one new hydrophilic lenses made by 3 manufacturers were randomly selected from an optometry clinic for measurement and inspection. Approximately 60% of the base-curve specifications fell within the following ranges for the measured dimensions: Bausch & Lomb Soflens contact lenses, less than 0.150 mm; Milton Roy Naturvue lenses, less than 0.375 mm; Soft Lens Inc. Hydrocurve, less than 0.225 mm. More than 65% of the lenses supplied by all the manufactures were within 0.25 D of the power specification. About two-thirds or more of all lenses had a central thickness and overall diameter within 0.04 mm and 0.40 mm, respectively, of the manufacturers' specifications, although there were notable differences among manufacturers. Most of these new lenses exhibited surface scratches and other surface defects, and many lenses had edge defects.

The "aging" of a HEMA contact lens.

The physical characteristics and attendant patient complaints associated with termination of the useful service lives of 26 HEMA lenses are compared with the characteristics of a control (undispensed) population of such lenses.