Patient use of smartphones to communicate subjective data in clinical trials

Purpose. Various methods have been used in clinical trials to collect time-sensitive subjective responses, including study diaries, telephone interviews, and use of text messaging. However, all of these methods are limited by the uncertainty of when the participants enrolled in the study actually record their responses. This technical note reports on the utility of the BlackBerry smartphone to collect such data and why such a system provides advantages over other methods to report subjective ratings in clinical studies.

Methods. The Centre for Contact Lens Research developed an on-line web-enabled system that permits participants to record and immediately transmit subjective rating scores in numerical form directly into a web-enabled database. This, combined with the utility of BlackBerrys, enabled time-specific e-mail requests to be sent to the study participants and then for that data to be simultaneously transmitted to the web-enabled database. This system has been used in several clinical trials conducted at the Centre for Contact Lens Research, in which data were collected at various times and in several specific locations or environments.

Results. In the clinical trials conducted using this system, participants provided responses on 97.5% of occasions to the requests for data generated by the automated system. When the request was for data on a set date, this method resulted in responses of 84.1% of the time.

Conclusions. The series of clinical trials reported here show the benefits of the utilization of the BlackBerry to collect time- or environment-sensitive data via a web-enabled system.

Reliability and validity of the Melbourne edge test and high/low contrast visual acuity chart

Purpose. The purposes of the study were to investigate the test-retest reliability and the validity of new versions of the Melbourne Edge Test (MET) and the High/Low Contrast Visual Acuity (H/LCVA) chart and to investigate the agreement between the original and new versions.

Methods. The MET original photographic version, MET new light box version, H/LCVA Chart original photographic version, H/LCVA Chart new printed version, and the Pelli-Robson chart were administered twice to one eye of 22 subjects with low vision and 20 soft contact lenses wearers.

Results. For the low vision group, the test-retest 95% limits of agreement were ±5.2 dB for the MET new light box version and ±0.39 logarithm of the minimum angle of resolution (logMAR) for the LCVA component of the H/LCVA new printed version. For the soft contact lens group, the test-retest 95% limits of agreement were ±2.1 dB for the MET new light box version and ± 0.26 logMAR for the LCVA component of the H/LCVA new printed version. Moderate to high correlations were obtained between contrast sensitivity tests, thus providing evidence of validity. Scores obtained for the new test versions were significantly higher than the original versions (p < 0.01).

Conclusions. Of all the tests administered, the MET original photographic version and the Pelli-Robson Chart had the highest test-retest reliability for the low vision group. For the soft contact lens group, the H/LCVA original version (low contrast letters, 18% Weber) and the Pelli-Robson Chart had the highest reliability.

Canadian uncorrected refractive error

Uncorrected refractive error is the leading cause of visual impairment in the world. In Canada there are potentially 2 million people with visual impairment that could be corrected by simply wearing glasses or contact lenses. This number will double in the next 20 years due to Canada’s rapidly ageing population. Visual impairment can seriously affect quality of life. People with vision problems are more likely to fall, have a higher risk of fractures and other injuries, and they may be more likely to limit or stop driving. Visual impairment is also an independent risk factor for increased mortality in older persons.

Effect of retinal image defocus on the thickness of the human choroid

PURPOSE: To describe the time-course and amplitude of changes to sub-foveal choroidal thickness (SFCT) induced by imposed hyperopic and myopic retinal defocus and to compare the responses in emmetropic and myopic subjects. METHODS: Twelve East Asian subjects (age: 18-34 years; six were emmetropic and six had myopia between -2.00 and -5.00 dioptres (D)) viewed a distant target (video movie at 6 m) for 60 min on two separate occasions while optical coherence tomography (OCT) images of the choroid were taken in both eyes every 5 min to monitor SFCT. On each occasion, one eye was optimally corrected for distance with a contact lens while the other eye wore a contact lens imposing either 2.00 D hyperopic or 2.00 D myopic retinal defocus. RESULTS: Baseline SFCT in myopic eyes (mean ± S.D.): 256 ± 42 μm was significantly less than in emmetropic eyes (423 ± 62 μm; p < 0.01) and was correlated with magnitude of myopia (-39 μm per dioptre of myopia, R(2) = 0.67: p < 0.01). Repeated measures anova (General Linear Model) analysis revealed that in both subject groups, 2.00 D of myopic defocus caused a rapid increase in SFCT in the defocussed eye (significant by 10 min, increasing to approximately 20 μm within 60 min: p < 0.01), with little change in the control eye. In contrast, 2.00 D of hyperopic defocus caused a decrease in SFCT in the experimental eye (significant by 20-35 min. SFCT decreased by approximately 20 μm within 60 min: p < 0.01) with little change in the control eye. CONCLUSIONS: Small but significant changes in SFCT (5-8%) were caused by retinal defocus. SFCT increased within 10 min of exposure to 2.00 D of monocular myopic defocus, but decreased more slowly in response to 2.00 D of monocular hyperopic defocus. In our relatively small sample we could detect no difference in the magnitude of changes to SFCT caused by defocus in myopic eyes compared to emmetropic eyes.

The epidemiology of dry eye in Melbourne, Australia

OBJECTIVE: To describe the epidemiology of dry eye in the adult population of Melbourne, Australia. DESIGN: A cross-sectional prevalence study. PARTICIPANTS: Participants were recruited by a household census from two of nine clusters of the Melbourne Visual Impairment Project, a population-based study of age-related eye disease in the 40 and older age group of Melbourne, Australia. Nine hundred and twenty-six (82.3% of eligible) people participated; 433 (46.8%) were male. They ranged in age from 40 to 97 years, with a mean of 59.2 years. MAIN OUTCOME MEASURES: Self-reported symptoms of dry eye were elicited by an interviewer-administered questionnaire. Four objective assessments of dry eye were made: Schirmer's test, tear film breakup time, rose bengal staining, and fluorescein corneal staining. A standardized clinical slit-lamp examination was performed on all participants. Dry eye for the individual signs or symptoms was defined as: rose bengal > 3, Schirmers < 8, tear film breakup time < 8, > 1/3 fluorescein staining, and severe symptoms (3 on a scale of 0 to 3). RESULTS: Dry eye was diagnosed as follows: 10.8% by rose bengal, 16.3% by Schirmer's test, 8.6% by tear film breakup time, 1.5% by fluorescein staining, 7.4% with two or more signs, and 5.5% with any severe symptom not attributed to hay fever. Women were more likely to report severe symptoms of dry eye (odds ratio [OR] = 1.85; 95% confidence limits [CL] = 1.01, 3.41). Risk factors for two or more signs of dry eye include age (OR = 1.04; 95% CL = 1.01, 1.06), and self-report of arthritis (OR = 3.27; 95% CL = 1.74, 6.17). These results were not changed after excluding the 21 people (2.27%) who wore contact lenses. CONCLUSIONS: These are the first reported population-based data of dry eye in Australia. The prevalence of dry eye varies by sign and symptom.

Human corneal epithelial cell shedding and fluorescein staining in response to silicone hydrogel lenses and contact lens disinfecting solutions

A pilot study was conducted to evaluate human corneal epithelial cell shedding in response to wearing a silicone hydrogel contact lens/solution combination inducing corneal staining. The nature of ex vivo collected cells staining with fluorescein was also examined. A contralateral eye study was conducted in which up to eight participants were unilaterally exposed to a multipurpose contact lens solution/silicone hydrogel lens combination previously shown to induce corneal staining (renu® fresh™ and balafilcon A; test eye), with the other eye using a combination of balafilcon A soaked in a hydrogen peroxide care system (Clear Care®; control eye). Lenses were worn for 2, 4 or 6 hours. Corneal staining was graded after lens removal. The Ocular Surface Cell Collection Apparatus was used to collect cells from the cornea and the contact lens. In the test eye, maximum solution-induced corneal staining (SICS) was observed after 2 hours of lens wear (reducing significantly by 4 hours; p < 0.001). There were significantly more cells collected from the test eye after 4 hours of lens wear when compared to the control eye and the collection from the test eye after 2 hours (for both; n = 5; p < 0.001). The total cell yield at 4 hours was 813 ± 333 and 455 ± 218 for the test and control eyes, respectively (N = 5, triplicate, p = 0.003). A number of cells were observed to have taken up the fluorescein dye from the initial fluorescein instillation. Confocal microscopy of fluorescein-stained cells revealed that fluorescein was present throughout the cell cytoplasm and was retained in the cells for many hours after recovery from the corneal surface. This pilot study indicates that increased epithelial cell shedding was associated with a lens-solution combination which induces SICS. Our data provides insight into the transient nature of the SICS reaction and the nature of fluorescein staining observed in SICS.

An international survey of toric contact lens prescribing

To characterize toric contact lens prescribing worldwide. Up to 1,000 survey forms were sent to contact lens fitters in up to 39 countries between January and March every year for 5 consecutive years (2007–2011). Practitioners were asked to record data relating to the first 10 contact lens fits or refits performed after receiving the survey form. Only data for toric and spherical soft lens fits were analyzed. Survey data collected since 1996 were also analyzed for 7 nations to assess toric lens fitting trends since that time. Data were collected in relation to 21,150 toric fits (25%) and 62,150 spherical fits (75%). Toric prescribing ranged from 6% of lenses in Russia to 48% in Portugal. Compared with spherical fittings, toric fittings can be characterized as follows: older age (29.8 ± 11.4 years vs. 27.6 ± 10.8 years for spherical lenses); men are overrepresented (38% vs. 34%); greater proportion of new fits (39% vs. 32%); use of silicone hydrogel lenses (49% vs. 39%); and lower proportion of daily disposable lenses (14% vs. 28%). There has been a continuous increase in toric lens prescribing between 1996 and 2011. The proportion of toric lens fits was positively related to the gross domestic product at purchasing power parity per capita for year 2011 (r2 = 0.21; P=0.004). At the present time, in the majority of countries surveyed, toric soft contact lens prescribing falls short of that required to correct clinically significant astigmatism (≥0.75 diopters) in all lens wearers.

Trends in US contact lens prescribing 2002 to 2014

Purpose To document contact lens prescribing patterns in the United States between 2002 and 2014. Methods A survey of contact lens prescribing trends was conducted each year between 2002 and 2014, inclusive. Randomly selected contact lens practitioners were asked to provide information relating to 10 consecutive contact lens fits between January and March each year. Results Over the 13-year survey period, 1650 survey forms were received from US practitioners representing details of 7702 contact lens fits. The mean (±SD) age of lens wearers was 33.6 (±15.2) years, of whom 65.2% were female. Rigid lens new fits decreased from 13.0% in 2002 to 9.4% in 2014. Across this period, silicone hydrogels have replaced mid water contact lens hydrogels as the soft lens material of choice. Toric lenses represented about 25 to 30% of all soft lens fits. Multifocal soft lenses are generally preferred to monovision. Daily disposable lens fits have recently increased, and in 2014, they represented 27.1% of all soft lens fits. Most lenses are prescribed on 1 to 2 weekly or monthly lens replacement regimen. Extended wear remains a minority lens wearing modality. The vast majority of those wearing reusable lenses use multipurpose lens care solutions. Lenses are mostly worn 7 d/wk. Conclusions This survey has revealed prescribing trends and preferences in the United States over the past 13 years.

Clinical performance of an innovative back surface multifocal contact lens in correcting presbyopia

Purpose: This prospective study was designed to subjectively and objectively evaluate the performance of an aspheric multifocal back surface rigid gas permeable (RGP) contact lens. The multifocal element of this lens design consisted of an aspheric optical zone that varied according to the patient's ametropia, corneal topography, and required reading addition.

Methods: We fit 28 presbyopic subjects with an aspheric multifocal back surface RGP contact lens (age range: 45 to 68 years). Reading additions ranged from +0.75 D to +2.50 D. Subjects were assessed initially and at 2, 6, and 12 weeks for ocular changes, visual performance, and subjective responses.

Results: We required 116 RGP lenses to achieve an acceptable fit and visual acuity in 28 subjects (55 eyes). At the final visit, the distance logMAR acuity with the multifocal contact lens (+0.12 +/-0.10) was not statistically different (t=-0.623, P= 0.5388) from spectacle acuity at the initial visit (+0.10 +/-0.12). The near logMAR acuity with the multifocal contact lens at the final visit (0.36 +/- 0.12) was not statistically different from that for near acuity with spectacles at the initial visit (0.33 +/- 0.13). No slit lamp signs worsened during the study. A reduction in myopia of 0.67 D was noted by the final visit. Spectacle blur was noted if the acuity at the initial refraction was compared to the acuity with the same refraction at the final visit (t= -3.287, P= 0.0028) but not when the refractive changes were incorporated (t= 1.058, P= 0.3127). All subjects rated the performance of the lenses very highly: comfort, 86%; distance acuity, 83%; near acuity, 73%; and stability of vision, 74%. Twenty-four subjects (86%) chose the multifocal contact lens as their preference.

Conclusion: We demonstrated that a multifocal design is able to provide acceptable distance and near correction for presbyopic patients. The aspheric geometry required can be optimized for a given patient by considering his/her degree of ametropia, as well as the corneal topography.

Comfort and adaptation to silicone hydrogel lenses for daily wear

Objectives. To investigate initial comfort and adaptation of currently successful low oxygen transmissibility soft lens wearers refitted with silicone hydrogel (SH) lenses for daily wear.

Methods. Fifty-five subjects were enrolled in a subject-masked 5-month clinical trial in which they wore 5 SH lenses in a randomized, crossover design. Comfort, burning, and dryness were rated on scales of 0 to 100 immediately on insertion and the time for lens settling was recorded. Symptoms were then rated at various times, using BlackBerry wireless communication devices (Research in Motion, Waterloo, Canada), during the day for 2 cycles of 2 weeks wear for each lens type.

Results. Comfort immediately on insertion varied between lens types (P=0.002). All lens types were reported by the subjects to have settled within 30 to 45 sec of insertion (P=0.14) and settled comfort was greater than comfort immediately on insertion (P<0.001). Comfort within the first hour of wear also varied between lens types (P=0.02). Comfort during the day decreased significantly for all lenses (P=0.001), but there was no difference between lenses (P=0.19) and no effect of lens age (P=0.15). The wearing times were greater with the SH lenses than the habitual lenses worn before study commencement (P=0.001). Overall performance of the lenses after 4 weeks was high, with no difference between lenses (P=0.45).

Conclusions. Initial comfort and adaptation to all SH lenses were good and no differences in the overall ratings were found between the 5 SH lenses investigated. Decreased comfort was noted later in the day with all lens types, but longer wearing times were reported with the SH lenses than previous hydroxyethyl methacrylate-based lenses.

Investigation of the performance of the menifocal Z gas-permeable bifocal contact lens during continuous wear

Purpose. The Menifocal Z is an alternating vision, concentric, bifocal gas-permeable (GP) contact lens; center distance is connected to near periphery by a smooth transition zone. The lens is produced using tisilfocon A (Menicon Z material), which is approved for up to 30 days of continuous wear (CW). The aim of this study was to evaluate the clinical performance of the Menifocal Z when worn for up to 30 days of CW for 6 months.

Methods. Thirty-five existing GP lens wearers were enrolled in the study. Subjects were fitted with Menifocal Z lenses and follow-up visits were conducted after 2 weeks of daily wear and 1 day, 1 week, 6 weeks, 3 and 6 months of CW. A range of objective and subjective clinical performance measures were assessed, including distance and near visual acuity, the physiological response to CW, and subjective evaluation of vision and comfort.

Results. Twenty-seven subjects (77%) completed the study and eight (23%) discontinued: five (14%) as a result of lens-related problems (four vision, one comfort) and three (9%) as a result of non-lens related reasons. Average CW time achieved by the subjects was 22 ± 2 days. Mean binocular logarithm of the minimum angle of resolution (logMAR) acuities at 6 months were: high contrast distance 0.03 (20/20-), low contrast distance 0.63 (20/80-), and high contrast near 0.26 (20/25, N4). Adverse responses and lens binding were minimal, and there were no significant increases in corneal staining, corneal vascularization, or superior palpebral conjunctival papillae over time (p > 0.05). Problems with night vision (distance and near) with the lenses were the most common difficulties reported by the subjects.

Conclusions. The Menifocal Z appears to be a promising option for presbyopic vision correction, providing successful correction of distance and near vision in a group of experienced GP lens wearers. The hyper Dk tisilfocon A (Menicon Z) material allowed for safe wear of the lenses on a CW basis.