Cristina M. Schnider

The effects of 2 week senofilcon—A silicone hydrogel contact lens daily wear on tear functions and ocular surface health status

PURPOSE To prospectively investigate the effects of 2 week senofilcon A contact lens (CL) daily wear on the functional visual acuity (VA), ocular surface and tear film. METHODS Seventeen right eyes of 17 senofilcon A CL wearers without any ocular or systemic diseases were examined before and 2 weeks after lens wear. Visual acuity measurements, tear evaporation rate, ELISA for tear cytokines, strip meniscometry, tear lipid layer interferometry, tear film break-up time (BUT), in vivo confocal microscopy, corneal sensitivity, ocular surface vital staining, Schirmer I test and brush cytology for MUC5AC mRNA expression were performed before and after CL wear. RESULTS The best corrected Landolt VA, functional VA parameters, the mean lipid layer interferometry grades, tear evaporation rates, Schirmer test values, vital staining scores and in vivo confocal microscopy parameters did not show any significant differences after 2 weeks of CL wear. The tear film BUT showed a significant decrease together with a significant down regulation of MUC5 AC mRNA expression after CL wear. A statistically significant elevation in the mean tear interleukin (IL)-6 concentration was also observed after 2 weeks of CL wear. CONCLUSIONS Two week senofilcon A daily CL wear seems to be associated with tear instability, a decrease in MUC5AC expression, and elevation of IL-6 in tears without significant alterations in epithelial damage scores or in the morphology or density of in vivo keratoconjunctival cells and nerves. Alterations associated with long term wear and patients with dry eye disease need to be studied in future trials.

The role of oxidative stress and inflammation in conjunctivochalasis

Purpose. To investigate the status of oxidative stress and histopathologic alterations in patients with conjunctivochalasis and compare the findings with those in healthy control subjects. Methods. Eleven patients (n = 20 eyes) with Yokoi grade 3 conjunctivochalasis and 11 health control subjects (n = 22 eyes) were prospectively recruited. ELISA for tear hexanoyl-lysine (HEL) and inflammatory cytokines, tear film break-up time tests, Schirmer test measurements, and fluorescein and rose bengal vital staining were performed. Conjunctival specimens obtained during surgery for conjunctivochalasis and cataract underwent immunohistochemical staining for HEL+8-OHdG, MMP-3, and MMP-9, and positively stained cells were counted. Transmission electron microscopy was also performed, with staining for elastic fibers in the conjunctival stroma. Results. The mean tear stability and vital staining scores were significantly worse in the conjunctivochalasis patients than in the control subjects. The tear HEL and tear cytokine levels showed significantly higher values in eyes with conjunctivochalasis. IL-1beta and IL-6 levels showed a significant correlation with corneal epithelial damage. IL-1beta and TNFalpha showed a significant correlation with 8-OHdG-stained cell counts. Specimens from patients with conjunctivochalasis revealed a significantly higher number of cells positively stained for HEL, 8-OHdG, MMP-3, and MMP-9 than did specimens from age- and sex-matched control subjects. Transmission electron microscopy showed decreased intercellular cohesiveness, with the conjunctival stroma showing an accumulation of elastic fibers. Conclusions. Lipid and DNA oxidative stress were present in the conjunctiva. Increased tear inflammation seemed to coexist with loss of conjunctival epithelial cohesiveness and increased collagenolytic activity, which may explain the conjunctival laxity observed in patients with conjunctivochalasis.

UV-B exposure to the eye depending on solar altitude

Purpose:To assess the validity of the solar ultraviolet index (UVI) as a determiner of eye risk under different conditions of facial profiles and orientation, and reflected light. Methods:Ocular UV radiation (UVR) exposure was measured as a function of the time of the day (solar altitude) using a two-dummy-type mannequin dosimetry system with embedded UVR (260-310 nm) sensors, in September and November in Kanazawa, Japan, on a motorized sun-tracking mount with one dummy face directed toward the sun and the other away from the sun. Results:A bimodal distribution of UV-B exposure was found in September for the face directed toward the sun, which differed dramatically from the pattern of ambient UVR exposure and measurements taken on the top of the head and those for the eye taken later in the year. Although the overall level was lower, a higher solar altitude is associated with higher UVR exposure in the condition facing away from the sun. Conclusions:The UVI is based on ambient solar radiation on an unobstructed horizontal plane similar to our measures taken on the top of the head, which differed so much from our measures of ocular exposure that UVI as a determiner of eye risk is deemed invalid. The use of the UVI as an indicator for the need for eye protection can be seriously misleading. Doctors should caution patients with regard to this problem, and eye protection may be warranted throughout the year.

Corneal topography and soft contact lens fit.

Purpose. To determine which ocular topography variables affect soft contact lens fit. Methods. Fifty subjects each wore three pairs of soft lenses in random succession (Vistakon Acuvue 2, Vistakon Acuvue Advance, Ciba Vision Night & Day), and various aspects of lens fit were evaluated. The steeper base curves of each type were worn in one eye and the flatter base curves in the other eye. Corneal topography data were collected using a Medmont E300 corneal topographer (Camberwell, Australia). Corneal curvature, shape factor (SF), and corneal height were measured over a 10 mm chord and also over the maximum measurable diameter. These were measured in the horizontal, vertical, steepest, and flattest meridians. Results. With each lens type, the steeper base curve provided the best fit on the greatest proportion of eyes and the significant differences in various aspects of fit were noted between base curves. For each lens type, there was no significant difference in mean K-reading between those eyes best fit with the steeper base curve and those eyes best fit with the flatter base curve. Two of the lenses showed a positive correlation between centration and horizontal corneal height (maximum), whereas one lens showed a negative correlation between centration and horizontal SF (SF = e2). Several lenses showed a positive correlation between post-blink movement and horizontal or vertical corneal SF. Conclusions. The measurement of corneal topography using current Placido disc instrumentation allows a better prediction of soft lens fit than by keratometry, but it is not reliable enough to enable accurate selection of the best fitting base curve. Some correlations are evident between corneal measurements; however, trial fitting remains the method of choice for selection of soft lens base curve.

The impact of silicone hydrogel materials on overnight corneal swelling.

Purpose. To identify the corneal swelling response associated with silicone hydrogel contact lens wear. Methods. Twenty-five subjects were recruited to participate in this single-center, controlled, single-masked, clinical trial. The corneal swelling response was evaluated by central corneal pachymetry after overnight wear of balafilcon A, etafilcon A, lotrafilcon A, senofilcon A, and no lens wear. More specifically, after 8 hours of closed-eye wear of each material, corneal thickness was measured immediately on eye opening, in addition to the first 4 hours of open-eye wear. Paired t tests were used to compare the swelling response from each condition to that associated with senofilcon A, and given the numerous statistical comparisons, a P value of ≤0.01 was considered significant. Results. At eye opening, there was no difference in the swelling response when comparing balafilcon A (1.35%), lotrafilcon A (1.22%), or no lens wear (0.77%) to senofilcon A (1.40%), although the swelling response associated with etafilcon A was significantly greater (P<0.001) than that associated with senofilcon A. There were no differences between balafilcon A, lotrafilcon A, and no lens wear compared to senofilcon A during the open-eye deswelling period. However, 1 hour after eye opening, corneal swelling remained significantly greater with etafilcon A than with senofilcon A (1.76% vs. –0.51%, respectively, P=0.01), although no other time-specific comparisons differed. Conclusions. Silicone hydrogel lenses, with high oxygen transmissibilities, are associated with very little corneal swelling after overnight wear of the lenses.

Passive cigarette smoke exposure and soft contact lens wear.

Purpose. To prospectively investigate the effects of passive cigarette smoke exposure on the ocular surface and tear film in soft contact lens (SCL) wearers. Methods. Twelve right eyes of 12 SCL wearers without any ocular or systemic diseases and 10 right eyes of 10 subjects who never wore CLs were examined before and 2 h after 5 min of passive cigarette smoke exposure in a controlled smoke chamber. Tear evaporation rate measurement, tear film break-up time (TBUT) examination, ocular surface fluorescein, rose bengal stainings, and Schirmer I test were performed at each visit. Results. The mean tear evaporation rates, TBUTs, and vital staining scores were significantly worse in CL wearers compared with healthy control subjects. TBUTs showed significant worsening after passive smoke exposure in both groups. The mean tear evaporation rate and vital staining scores showed a significant increase with brief passive smoke exposure in subjects not wearing CLs but not in CL wearers. Conclusion. Even brief passive exposure to cigarette smoke is associated with adverse effects on the ocular surface as evidenced by an increase in tear instability and damage to the ocular surface epithelia in SCL wearers and non-CL wearers.

Clinical performance and patient preferences for hydrogel versus RGP lenses: A crossover study

Abstract A clinical trial was conducted with 20 subjects to compare patient preference and corneal physiology for hydrogel (soft) contact lenses to that with rigid gas permeable (RGP) contact lenses. Each subject wore each type of lens for 6 weeks and then switched materials for the remaining 6 weeks. Initially, half the subjects wore RGP contact lenses, while the other half wore soft contact lenses. Subjects were monitored after 1 week, 3 weeks, and 6 weeks of wear with each lens type. At the completion of the study, eight of the subjects preferred the RGP contact lenses while 12 of the subjects preferred the soft contact lenses. Excluding foreign body staining, all subjects demonstrated corneal fluorescein staining with soft contact lenses equal to or greater than that found with the RGP contact lenses. Although five subjects could not fully adapt to the RGP lenses, seven of the 12 subjects who preferred the soft contact lenses were also “successful” RGP lens wearers. “Successful” was defined as being that the lenses provided clear vision and good comfort without interrupting corneal physiology. The results of this study indicate that 75% of subjects traditionally deemed more suitable for soft lenses could successfully wear RGP lenses and that 40% of the subjects may actually prefer them.

Effect of patient personality profile and verbal presentation on successful rigid contact lens adaptation, satisfaction and compliance.

Background. Rigid gas permeable (RGP) lenses have numerous benefits, including quality of vision, ocular health, and reduction of myopic progression in young people. Nevertheless, RGP lens use is not increasing in the United States. It is possible that certain patient personality characteristics and/or how a practitioner presents RGP lenses to a new patient may affect satisfaction and success. The purpose of this study was to evaluate the effect of individual patients personality and the practitioners method of presenting RGP lenses to new patients on their ability to adapt to these lenses. Methods. Forty-nine subjects, all noncontact lens wearers, were entered into this 1-month study, which was conducted at both the University of Missouri-St. Louis School of Optometry and the Pacific University College of Optometry. All subjects initially completed standardized questionnaires pertaining to locus of control, openness to new experiences, and motivation/expectations. After diagnostic fitting with a RGP lens material, the subjects were placed into one of the following three groups: (1) Fear-Arousing Non-Enthused; (2) Neutral Content Non-Enthused; or (3) Neutral Content Enthused. They observed one of three video presentations on RGP lens wear. Subjects submitted daily questionnaires providing their evaluation of such factors as comfort, wearing time, and handling. Results. The results showed that there was a significant difference (x2=6.99; p<0.05) among the different groups in the number of dropouts: 6/19 with the Fear-Arousing Non-Enthused group, 2/17 with the Neutral Content Non-Enthused group, and 0/13 with the Neutral Content Enthused group. There was also a significant difference (ANOVA F=4.1, p<0.05) among the groups on compliance, with the Neutral Content Enthused group demonstrating greater compliance. In terms of satisfaction, there was no significant difference among presentation groups. Conclusion. It was concluded that the method of presentation is important for successful RGP contact lens wear. If presented with genuine interest and a positive and realistic attitude, patients are more likely to succeed in RGP lens wear during the initial critical period.

Complications associated with RGP extended wear: two case reports

This paper presents two case reports that indicate the need for caution when fitting and assessing the RGP extended wear patient. Problems that arose related to corneal erosion, lens adherence and corneal distortion.

Normative data and control studies of flash VEP's for comparison to a clinical population.

ABSTRACT The effects of aging, interocular comparisons, pupil dilation, iris pigmentation, and simulated cataracts on bright flash visual evoked potentials (VEPs) of normal observers were studied to assess the flash VEP as a potential predictor of postsurgical visual function in cataract patients. Seventy‐six observers (from 20 to 80 years old) were tested for age differences in flash VEPs. Implicit time measures for transient responses increased significantly as a function of age, but neither transient nor steady‐state response amplitudes were altered significantly. Moreover, no signficant changes in VEPs occurred as a function of interocular comparisons, pupil dilation, or differences in iris pigmentation of normal observers. Simulation of cataracts with 14 observers did not affect implicit time measures, but did change response amplitudes significantly. Therefore, implicit time measures of cataract patients should be compared either to those of normal age‐matched controls or, in the case of a unilateral problem, to the normal fellow eye. Delayed implicit time measures, after the appropriate comparison, suggest optic nerve/ pathway dysfunction. However, comparisons of amplitude measures require compensation for opacity density.