John McNally

Risk factors for corneal infiltrative events with 30-night continuous wear of silicone hydrogel lenses.

Purpose. This analysis reports on risk factors for corneal infiltrative events from a 1-year, randomized clinical trial of lotrafilcon A lenses. Methods. Six hundred fifty-eight subjects randomized to lotrafilcon A lenses were observed in a 1-year clinical trial in the United States. Risk factors gathered at baseline were analyzed to determine their association with corneal infiltrative events. Results. Factors examined but not found to be associated with events were male sex, history of extended or daily lens wear, refractive error, neovascularization, or assessment of lens fit. Significant factors included subject age 18 to 29 years, smoking, smoking and young age combined, history of corneal scar, contact lens acute red eye (CLARE), and corneal infiltrates. Conclusion. Risk factors for corneal infiltrative events with silicone hydrogel lenses worn for 30 nights of continuous wear have been identified. Wearers with a history of inflammatory events such as contact lens peripheral ulcer or CLARE should consider 30-night continuous wear with these lenses. Careful counseling of wearers who smoke is advised.

Effect of lens base curve on subjective comfort and assessment of fit with silicone hydrogel continuous wear contact lenses

Purpose. To study the effect of base curve on subjective comfort of silicone hydrogel extended wear lenses. Methods. Ninety-five subjects were first trial fitted with 8.6-mm base curve lotrafilcon A (Focus Night & Day) lenses and then with 8.4-mm lenses only if poor subjective comfort or poor fit was present. Comfort and fit were assessed after 15 min. Subjects with discomfort or signs of poor fit were then trial fitted with 8.4-mm lenses. Results. Of 190 eyes, 74.2% were fitted with 8.6-mm lenses, and 23.7% required 8.4-mm lenses. Two (2.1%) subjects could not be fitted with either base curve. Mean steep keratometry (K) reading for eyes dispensed with 8.6-mm lenses was 43.88 D and 45.56 D for eyes dispensed in the 8.4-mm lenses (p < 0.001). Conclusions. A clinically useful criterion showing the need for 8.4-mm lenses was steep K of ≥45.50 D; 77% of these eyes required the steeper lens for good comfort and fit. Subjective discomfort with 8.6-mm lenses was also a useful signal for the need of a steeper lens; mean comfort scores for those subjects rose from 6.33 with 8.6-mm lenses to 9.44 with the 8.4-mm lenses for eyes requiring the steeper lens (p < 0.001).

The clinical performance of a silicone hydrogel lens for daily wear in an Asian population.

Purpose. To evaluate slitlamp findings, frequency and severity of symptoms, and wearing time with a silicone hydrogel contact lens when used for daily wear by patients of Asian ethnicity. Methods. This was a five-site, 88-patient, prospective, open-label study involving 1 month of daily wear of lotrafilcon A lenses (Focus NIGHT & DAY, CIBA Vision, Duluth, GA) among adapted soft lens wearers previously wearing etafilcon A (ACUVUE 2, Johnson & Johnson Vision Care, Jacksonville, FL) or polymacon (Optima FW, Bausch & Lomb, Rochester, NY) lenses. Results. Statistically significant improvements in conjunctival redness, limbal redness, and corneal neovascularization were reported after 1 week and 1 month of wear. Patients reported statistically significant improvements in subjective symptoms of redness, dryness during the day, and dryness at the end of the day. More patients reported increased than reduced average daily wear time and average daily comfortable wear time with the silicone hydrogel lens. Conclusions. Significant improvements in clinical signs and subjective symptoms may occur when some patients of Asian ethnicity wearing conventional hydrogel lenses for daily wear are refitted with silicone hydrogel lenses for daily wear.

Corneal epithelial disruption with extremely thin hydrogel lenses

Recent reports indicate that acute and chronic adverse effects of extended wear contact lenses may be overcome with lenses of higher oxygen transmissibility. For hydrogel lenses, higher water content and thinner lenses have been proposed. Several studies have shown corneal epithelial disturbance with thin high water hydrogel lenses. In this study hydrogel lenses of 38, 55, 65 and 75% water were tested in a ‐3.00 D monocurve lens design and in a parallel lens design. Center thicknesses were the thinnest yet reported, ranging from 0.022 to 0.036 mm. Subjects stayed in a low humidity (25–35%) environment for a 6 hour testing period. With regard to epithelial disturbance, the results show a trend that the higher the water content the earlier the onset, the greater the maximum level and the greater percentage subjects that exhibited the epithelial disruption. The ‐3.00 D lenses produced more epithelial disturbance than the parallel designs. The location of the disturbed epithelium was central for the ‐ 3.00 D lenses and along the lid margins for the parallel lenses. Between onset and termination of the study at six hours, the severity of epithelial disturbance waxed and waned. These results do not concur with the current understanding of the mechanism of epithelial disturbance with thin high water hydrogel lenses and suggest the need for further evaluations.

Session VI: How Popular Will Continuous Wear Become?: Discussion and Summary

The ideal case for why daily wear (DW) is preferable to extended wear (EW) was presented by Dr. Barry Weissman, who was tasked with the same assignment at the previous Keystone Symposium in 1989. The principal reason given then and now for primacy of DW involves lens-induced hypoxia in EW with an increase in risk for the most feared complication: microbial keratitis (MK). Although it is conceded that the new hyper-oxygen transmissible materials seem to have overcome lens-related hypoxia issues in DW and EW, there is yet a paucity of new information on MK rates with the new lenses, and hence, caution is advised until final studies are available. Thus, a significant factor for the popularity of continuous wear may be practitioner-related reluctance to recommend EW to patients. However, Dr. Arthur Epstein makes both the case for strong and long-standing patient preferences for EW and cites the availability of preliminary data demonstrating that MK rates using the new hyper-Dk lenses have apparently decreased from 10to 40-fold. Large-scale clinical trial data for the performance of each of the three new hyper-oxygen transmissible lenses was then presented by Drs. Gleason (The rigid gas-permeable [RGP] Menicon Z lens; Menicon, Nagoya, Japan), Brennan (the Bausch and Lomb PureVision lens; Rochester, NY), and Chalmers (Ciba Vision Focus Night & Day lens; Duluth, GA). The panel noted as a group: (1) the overall superior clinical performance of each of the novel hyper-Dk lenses as compared with a conventional, hydrogel control lens (Acuvue; Vistakon, Inc., Jacksonville, FL), which seems related to increased oxygen transmission of the hyper-Dk RGP and silicone hydrogel materials; (2) the interesting and unexpected lack of apparent hyper-Dk RGP lens binding to the cornea in successful 30-night EW; (3) the apparent wettability, stability, and comfort of the new materials; and (4) the emergence, for the first time, of significant patient-specific risk factors for adverse events, including MK (adolescent, men, and smokers) shown by Dr. Chalmers. Interestingly, the isolated cluster of Australian cases of MK associated with wear of silicone hydrogel lenses also occurred in young, male swimmers. Taken together, the discussants believe that this exciting new data begins to build the first profile of a higher-risk EW patient whose exclusion or more careful clinical monitoring could further reduce potential risk for MK. The question of overall RGP safetydiscomfort problems versus silicone hydrogels was also explored. The hyper-RGP clinical data demonstrated expected 3 and 9 o’clock staining but also revealed that nearly two thirds of study patients achieved EW greater than 22 days. However, RGP lenses are often not as comfortable as their silicone hydrogel counterparts, and there was a panel concession that the percentage of patients who select RGP EW may continue to be smaller world wide than continuous wear of silicone hydrogel lenses. The interesting exception to this raised by the panel was the recent re-emerging intense interest in orthokeratology, where new hyper-Dk rigid materials may provide a safer (less MK) basis for re-examination of this old technique as a reasonable option for the correction of low, spherical myopia. Overall, the panel did not apparently conclude that the clinical performance of any one of the new hyper-oxygen transmissible lenses was superior to the others; but, taken as a group, the new hyper-Dk lenses are clearly superior in efficacy and potential safety to their conventional counterparts. As such, it is expected that this group will rapidly displace conventional lenses in both DW and EW modalities. However, the excitement of these new lenses is the demonstration of safe EW up to 30-night use. This represents the clear victory of new technology over past, hypoxia-related complications, including MK. Issues of the clinical importance of tear exchange rates by lens type were also discussed. It is unknown at this time whether promotion of increased rates of tear exchange under silicone hydrogel lenses is a vitally important goal for corneal health. However, all agree that this is an important area for future research. Dr. Oliver Schein wisely tempered enthusiasm for the safety of continuous wear with the new materials. His discussion indicates that risk data for MK can be rapidly assessed by somewhat more inexpensive studies but that documentation of decreased incidence rates for MK are more complex and will take more time and resources to accomplish. All agreed that preliminary pilot data from two independent sources seems to indicate a substantial reduction in risk for MK (10to 40-fold). Future epidemiologic studies are clearly needed to confirm this information. If this is the case, and if practitioners are willing to look objectively at and accept the highly favorable biologic results with the new hyper-oxygen transmitting RGP and silicone hydrogel lenses presented in this publication, the future for the long-sought goal of safe, effective, and widespread continuous contact lens use has never been brighter.