The CLAO journal : official publication of the Contact Lens Association of Ophthalmologists, Inc最新文献

Purpose: The SEED Company, Ltd. developed the novel SEED S-1, a rigid gas-permeable contact lens (RGPCL) with a hydrophilic monomer grafted onto its surface by polymerization. This article describes the use of the polymerized graft material poly(ethylene glycol) (PEG) used as a biomaterial, and characterizes the surface of the RGPCL.

Methods: The grafting of PEG onto a RGPCL was carried out by plasma treatment and polymerization, and the characteristics of the RGPCL surface were obtained by measuring the water equilibrium contact angle and the surface zeta potential. The zeta potential was measured using an electrophoretic light-scattering photometer. Furthermore, the characteristics of the interaction between the polymer surface and protein was obtained by observing the relationship of adsorption between the protein and lipids and the polymer surfaces.

Results: The RGPCL became hydrophilic with increasing ethylene glycol units when the graft was polymerized onto the otherwise hydrophobic surface. After the graft polymerization of PEG onto the RGPCL, the surface zeta potentials increased to a negative static surface with the increased addition of ethylene glycol units. Additionally, the amount of adsorption of protein and lipids were decreased, respectively, as the ethylene glycol chain increased in length.

Conclusions: The hydrophobic surface of the RGPCL was changed to a hydrophilic surface by graft polymerization of PEG. This suggests that novel RGPCL surfaces can be designed by graft polymerization, using such ethylene glycol groups.

Purpose: The purpose of this study was to evaluate the safety of the Herrick Lacrimal Plug (HLP) (Lacrimedics, Eastsound, WA) by reviewing medical records obtained from patients in whom the HLP was implanted.

Methods: A total of 228, primarily dry-eye, patients who had received one or more HLP implants at 19 centers during 1994 were included in the review; both centers and patients were randomly selected for inclusion. Medical records were examined for evidence of adverse events, which were characterized by presumed relationship to treatment, time of occurrence, severity, treatment required, and clinical outcome. Patients were contacted by phone whenever possible to verify the accuracy of the information extracted from their medical records.

Results: A total of 35 adverse events likely, or definitively related to treatment, were recorded for 25 (11.0%) of 227 evaluable patients who were followed for 0 to 4.6 years (mean, 0.9 years). The most common adverse event was epiphora (21), followed by plug displacement (7), ocular irritation (5), ocular pain (1), and headache (1). Sixteen (7.0%) patients (15 epiphora, 1 headache) had one or more plugs removed using a perfusion technique, with symptoms resolving for 13 patients, reduced for one but persisting for the remaining two. None of the baseline or treatment variables were found to be predictors of the occurrence of an adverse event following plug implantation.

Discussion: Approximately 10% of the patients who underwent implantation with the HLP in this series presented with a device-related adverse event, most commonly epiphora, which usually resolved following plug removal with a saline perfusion method. For the two patients (0.9%) whose epiphora did not resolve following plug removal, both had the same symptom before plug implantation, so it is unclear if persistence was the result of plug retention in the lacrimal drainage system or merely continuation of a preexisting condition.

Purpose: This study examined the effects of a soft multifocal progressive contact lens on individual Zernike coefficients describing the aberrations of the eye.

Methods: Ocular wavefront aberrations (OWA) of 10 subjects not wearing contact lenses were quantified using a Shack-Hartmann aberrometer and were repeated after lens insertion (two lenses,+2 diopters [D], and -2D distance power, order of insertion was randomized). All data were captured and stored on computer. Each coefficient of the Zernike polynomials representing, coma, spherical aberration (SA), and the fifth-order aberrations were evaluated for each OWA. Pupil size was monitored using an infrared device.

Results: After subjecting the data to various permutations, the following relationships and chief findings were detected: (1) Comparing coefficients with and without lenses, significant correlations for coma (Z(1)3 [rho,theta], P=0.0056; -2D and P=0.0399, +2D); SA (Z(0)4 [rho,theta], P=0.0006; -2D; and P=0.0061,+2D). Fifth-order aberration (Z(-1)5 [rho,theta], P= 0.0029,+2D). (2) With the -2D lens, the average root-mean-square (RMS) value for the SA coefficient Z(4)4 (rho,theta) and fifth-order Z(-3)5 (rho,theta) increased (P=0.045 and 0.0392, respectively). (3) With the +2D lens, the average RMS value for fifth-order coefficient Z(1)5(rho,theta) increased (P=0.0278). (4) Coma (Z(1)3 [rho,theta] coefficient) correlated with pupil size (P<0.05). Initial mean (+/-SD) pupil size (mm) was 3.05 (0.499), and this did not change significantly.

Conclusions: Z(1)3(rho,theta) and Z(0)4(rho,theta) coefficients may be useful objective markers of success or failure for such contact lenses. The -2D lens had a more predictable effect on SA compared with the +2D lens design. The opposite occurs when considering the effects on the higher fifth-order order aberrations.

Purpose: This study evaluated the clinical performance of contact lens wear, primarily comfort and dryness during the daytime and at the end of the day, associated with the use of a multipurpose solution containing hydroxypropyl methylcellulose (HPMC), COMPLETE ComfortPLUS (Allergan, Irvine, CA) compared to a citrate-based multi-purpose disinfecting solution used without manual rubbing, NO RUB OPTI-FREE EXPRESS (Alcon, Ft. Worth, TX).

Methods: This randomized, investigator-masked, cross-over study was conducted with 64 subjects who underwent adaptation and were planned-replacement lens wearers. Each solution was used by the subject for 1 month, with a 1-week wash-out period during which the subject's own solutions were used. When new solutions were issued, new contact lenses also were dispensed.

Results: The level of comfort, the primary endpoint of the study, in the evening (on a 50-point scale) was rated better with OPTI-FREE EXPRESS at the end of the 1-month period of wear (mean 39 vs. 37, P=0.03). Dryness, the most frequently reported symptom, occurred at a similar level of rating with both care systems (P >0.05). Few other clinically significant differences between the regimens were noted.

Conclusions: The overall clinical performance of the citrate-based solution used without manual rubbing was similar to that of the solution containing HPMC. The subjective results of comfort-level and dryness with the two regimens demonstrated that the inclusion of HPMC did not provide unique performance advantages.

Purpose: This article reports a microbiologic study of two kinds of monthly frequent-replacement daily wear soft contact lenses, with different amounts of water content, in asymptomatic contact lens wearers.

Method: We studied 35 lenses of 18 patients who wear frequent-replacement soft contact lenses with a water content of 38% and 40 lenses of 20 patients using frequent-replacement contact lenses with a water content of 55%. The lenses worn by patients regularly for 1 month were removed from their eyes in a sterile manner on the 30th day and were studied microbiologically to isolate pathogenic agents.

Results: In the group of monthly frequent-replacement soft contact lenses with a water content of 38%, microorganisms were isolated at a rate of 91%; and in the group of monthly frequent-replacement soft contact lenses with a water content of 55%, microorganisms were isolated at a rate of 85%. When the two groups were compared, there was no statistically significant difference (P=0.31). Although coagulase-negative staphylococci, Corynebacterium spp, and gram-negative rods were detected in both groups, Staphylococcus aureus, non-hemolytic streptococci, Neisseriae spp, and Penicillium spp also were isolated in the group with the higher water content.

Conclusion: Bacteria spreading from the environment or from skin flora to the eyes showed more diversity in the group of frequent-replacement soft contact lenses with a high water content. Additionally, Penicillium spp also was isolated in this group. Therefore scrupulous attention to daily lens care is crucial for people who wear frequent-replacement soft contact lenses.

Purpose: Empirical fitting success is important to expanding the soft toric contact lens market. Previous study has lead to the hypothesis that lens flexure may alter expected fitting relationships and back vertex power (BVP) in situ. In this study, baseline topographic features as potential variables in predicting soft toric fitting success were analyzed.

Methods: One-hundred forty-nine eyes were empirically fit with back surface toric soft lenses after placido-based videokeratography was performed. Measurements recorded from baseline instantaneous maps included: flat simulated keratometry (Sim-K) value (in diopters) and axis, steep Sim-K value (in diopters) and axis, eccentricity of the flat meridian, and the form of corneal astigmatism. Astigmatism was classified as types I-V based upon differences between central and peripheral corneal toricity.

Results: Ninety-three of 149 (62.4%) eyes were successfully fit empirically with the first trial lens. One-hundred thirty-five of 149 (90.6%) eyes were ultimately successful after unsuccessful trial lenses were adjusted and reordered. There were no differences between the empirically fit success and failure groups in instrument reported eccentricity, Sim-K values, or Sim-K axes (P>0.05). Of 115 eyes classified for form of corneal astigmatism, 76 (66%) were classified with high or irregular peripheral astigmatism (types IV and V). There was a significant association between fitting success and the form of corneal toricity (P=0.0327). Thirty-nine of 115 (34%) eyes were classified as corneal types I-III (spherical or minimally toric corneal periphery) and were associated with empirical fitting success (P=0.0092).

Conclusion: Empirical soft toric fitting success can be anticipated in spherical corneas, central astigmatism, or corneas with peripheral toricity which matches the central toricity. However, high and irregular peripheral corneal toricity occurs in the majority of astigmatic patients. Corneal topography is a valuable tool to assess peripheral astigmatism which may be one factor influencing unexpected lens performance.

Purpose: To compare the percent hydration by wet weight of hydrogel contact lenses given by the manufacturers with the values obtained using the refractive index and the gravimetry methods.

Methods: We used a Valentine refractometer to determine the refractive index of new hydrogel contact lenses at equilibrium swelling in the original solution and container. From the refractive indexes we then obtained the percent hydration of the lenses using a previously prepared graph of refractive index vs percent hydration of saccharose in a phosphate buffer solution (pH 7.0). We used an electronic analytical balance of 0.01 mg resolution to obtain the weights of new lenses when dry and at equilibrium swelling dry, and calculated the percent hydration of the lenses from the difference of the wet and dry weights.

Results: The hydration values of the contact lenses obtained from the index of refraction differed more than those obtained by gravimetry from the values given by the manufacturers. Acuvue lenses were an exception-the difference for them was negligible.

Conclusion: Gravimetry is more accurate, but more cumbersome and time-consuming than the index of refraction for the determination of the hydration of the hydrogel contact lenses. However, when a fast and easy method is required to obtain the approximate hydration of hydrogel contact lenses, the use of the refractive index method can give acceptable results for most applications.

Purpose: Evaluate the ZEBRA 2000 (Z-10) bifocal contact lens on presbyopic and aphakic patients.

Methods: Thirty-eight patients, 37 presbyopes and one aphake, were fit in the Z-10 and evaluated for 6 months.

Results: Twenty patients (53%) completed 6 months of contact lens wear. Ten (26%) discontinued due to lens related problems, three (8%) discontinued due to other health problems, and five (13%) were lost to follow-up. Average refits per eye were 1.75. Average distance visual acuity was 20/25; average near visual acuity was J1.6; average wear time, 11 hours. Patient satisfaction was rated good in comfort and vision and fair in nighttime glare by patients' subjective evaluation.

Conclusions: The ZEBRA 2000 (Z-10) can be a useful addition in fitting the general presbyopic patient population.

Purpose: To characterize the nature and duration of contact lens training in ophthalmology residency training programs and to ascertain the comfort level of residents in fitting various types of contact lenses and in dealing with common contact lens-related complications.

Methods: Surveys were mailed to 126 ophthalmology residency program directors/coordinators and requested to be distributed to 1,381 ophthalmology residents. The questionnaire addressed issues related to contact lens training, hours of clinical and didactic training, comfort with fitting a variety of different types of contact lenses and dealing with common contact lens-related complications, and plans for incorporation of contact lens dispensing into future practice.

Results: Two hundred and forty-nine residents (18%) responded from 84 programs (67%). Most programs (87%) have some form of supervised contact lens training, frequently conducted by an optometrist (61% of programs), that consists of 20 hours or less of clinical experience and 20 hours or less of didactic training. A majority of the responding graduating residents (66%) feel comfortable fitting spherical soft contact lenses, while less than half of all residents feel comfortable fitting any other type of contact lens. In addition, most residents (65%) feel comfortable diagnosing and treating common contact lens-related complications.

Conclusions: Most ophthalmology residency programs offer some form of supervised contact lens training which allows a majority of residents to feel comfortable fitting only spherical soft contact lenses, while also dealing comfortably with most contact lens-related problems. A comparison with previous data suggests increasing comfort with fitting most types of contact lenses over the last decade.