Kathleen Watt

Microbial keratitis in overnight orthokeratology : review of the first 50 cases

Purpose. Despite growing evidence for clinical efficacy of orthokeratology (OK) for the temporary reduction of myopic refractive error, there has been an increasing number of reports of microbial keratitis (MK) in association with overnight wear of OK lenses. This article analyzes the first 50 cases of MK reported in overnight OK, in order to define the spectrum of the disease and to identify possible risk factors. Methods. All reported cases of presumed MK in overnight OK from 2001 onwards were included in the analysis. Demographic data of patients affected and lenses worn, and details of the disease process and possible risk factors were extracted from these reports. Results. Most cases of MK in OK were reported from East Asia (80%) and most affected patients were Asian (88%). The peak age range was from 9 to 15 years (61%). Although Pseudomonas aeruginosa was the predominant organism implicated in this series of cases (52%), an alarmingly high frequency of Acanthamoeba infection (30%) was found. Inappropriate lens care procedures, patient noncompliance with practitioner instructions, and persisting in lens wear despite discomfort emerged as potential risk factors. Conclusions. The high frequency of MK in overnight OK in young Asian patients is likely to reflect the demographics of the OK lens-wearing population. The high frequency of Acanthamoeba infection strongly suggests that tap water rinsing should be eliminated from the lens care regimen for overnight OK. This study does not reveal the absolute incidence or relative risk of MK in overnight OK, and it is therefore premature to ascribe increased risk to this lens-wearing modality compared with other contact lens modalities.

Trends in Microbial Keratitis Associated With Orthokeratology

Purpose. Orthokeratology is a clinical technique that uses reverse-geometry rigid gas-permeable contact lenses to alter corneal shape to provide temporary reduction of refractive error. Microbial keratitis is the most severe, potentially vision-threatening adverse response associated with orthokeratology contact lens wear. This article aims to review all reported cases of confirmed and presumed microbial keratitis associated with orthokeratology and to examine trends in microbial keratitis in orthokeratology over time. Methods. Cases of microbial keratitis associated with orthokeratology were identified from case reports published in the optometric, ophthalmologic, and vision science literature and published in abstract form for papers or posters presented at optometric or ophthalmologic conferences. Results. A total of 123 cases of microbial keratitis associated with orthokeratology have been reported since 2001, dating back to 1997. Most patients were female, East Asian, and aged between 8 and 15 years. The infectious organism was implicated as Pseudomonas aeruginosa for 46 (38%) of these cases and as Acanthamoeba species for 41 (33%) cases. The peak year for occurrence of microbial keratitis was 2001 and accounted for more than half (64 [52%] of 123) of all reported cases. All cases in this year were reported from East Asia, including China (47 cases), Taiwan (11 cases), and Hong Kong (6 cases). Conclusions. Although there has been an increasing number of reports of microbial keratitis associated with orthokeratology since 2001, most (85 [69%] of 123) of these cases occurred in East Asia, particularly in China and Taiwan, during a relatively short period, when regulation of this modality was limited. The high prevalence of cases of Acanthamoeba keratitis reported with this modality emphasizes the importance of eliminating the use of tap water in care regimens for overnight orthokeratology.

Myopia control during orthokeratology lens wear in children using a novel study design.

PURPOSE To investigate the effect of overnight orthokeratology (OK) contact lens wear on axial length growth in East Asian children with progressive myopia. DESIGN A prospective, randomized, contralateral-eye crossover study conducted over a 1-year period. PARTICIPANTS We enrolled 26 myopic children (age range, 10.8-17.0 years) of East Asian ethnicity. METHODS Subjects were fitted with overnight OK in 1 eye, chosen at random, and conventional rigid gas-permeable (GP) lenses for daytime wear in the contralateral eye. Lenses were worn for 6 months. After a 2-week recovery period without lens wear, lens-eye combinations were reversed and lens wear was continued for a further 6 months, followed by another 2-week recovery period without lens wear. Axial eye length was monitored at baseline and every 3 months using an IOLMaster biometer. Corneal topography (Medmont E300) and objective refraction (Shin-Nippon NVision-K 5001 autorefractor) were also measured to confirm that OK lens wear was efficacious in correcting myopia. MAIN OUTCOME MEASUREMENTS Axial length elongation and myopia progression with OK were compared with conventional daytime rigid contact lens wear. RESULTS After 6 months of lens wear, axial length had increased by 0.04±0.06 mm (mean±standard deviation) in the GP eye (P=0.011) but showed no change (-0.02±0.05 mm) in the OK eye (P=0.888). During the second 6-month phase of lens wear, in the OK eye there was no change from baseline in axial length at 12 months (-0.04±0.08 mm; P=0.218). However, in the GP eye, the 12-month increase in axial length was significant (0.09±0.09 mm; P<0.001). The GP lens-wearing eye showed progressive axial length growth throughout the study. CONCLUSIONS These results provide evidence that, at least in the initial months of lens wear, overnight OK inhibits axial eye growth and myopia progression compared with conventional GP lenses. Apparent shortening of axial length early in OK lens wear may reflect the contribution of OK-induced central corneal thinning, combined with choroidal thickening or recovery due to a reduction or neutralization of the myopiogenic stimulus to eye growth in these myopic children.

Microbial keratitis in orthokeratology: the Australian experience

Background:  This study was conducted to investigate the demographics of orthokeratology (OK) practice in Australia, to uncover any previously undocumented cases of serious adverse responses in OK, including microbial keratitis (MK), and to review the demographics of MK in OK in Australia.

A Possible Association Between Dry Eye Symptoms and Body Fat: A Prospective, Cross-Sectional Preliminary Study.

Objectives: To examine the relationship between dry eye symptoms and adiposity in a population study. Methods: A prospective cross-sectional single-visit preliminary study was designed to sample ocular symptoms and indices of adiposity in the general adult population. Patients recruited from the UNSW optometry clinic, the university campus and surrounding community, and overseas were invited to complete a survey composed of the short form Dry Eye Questionnaire (SFDEQ) (Dry Eye Questionnaire-5 or Contact Lens Dry Eye Questionnaire-8) and the Ocular Comfort Index (OCI) via hardcopy or online. Participants self-measured their weight, height, waist circumference (WC), and body fat % (optional). Associations between measures of adiposity (Body mass index [BMI], WC, and body fat %) and ocular symptoms scores (SFDEQ and OCI) were determined using Spearman correlation coefficients. Group differences were compared using independent t test. Results: Three hundred and five participants including 52 contact lens wearers completed the study and 78 of them measured body fat %. There was a moderate correlation between body fat % and dry eye symptoms (SFDEQ r=0.34, P=0.003; OCI r=0.32, P=0.004). The interaction between body fat % and gender, wear of contact lenses, and older age were shown to be significant predictors of less ocular comfort in multivariate analysis (F(3,74)=12.13, P<0.001). Conclusions: An association between adiposity measured by body fat % and symptoms of dry eye was demonstrated in the general adult population. Confirmation of these findings in a large study is required.

Attitudes and Barriers to Evidence-Based Practice in Optometry Educators

Purpose Evidence-based practice (EBP) is an essential component of good quality, patient-centered health care. This requires practitioners to acquire EBP skills and knowledge during undergraduate and continuing education. Evidence-based practice education exists in a range of health care disciplines, including optometry. Evidence-based practice education, however, depends on relevant skills and knowledge in educators. Courses and workshops exist for the development of EBP teaching skills in some areas of health care but not in optometry. Here, we describe a pilot workshop designed to enhance the teaching of EBP and to investigate the perspectives of optometric educators on EBP including their attitudes and perceived barriers to EBP and its teaching. Methods Twenty-seven optometric educators including 8 facilitators participated. Of these, 14 were academics (including the 8 facilitators) and 13 were practitioners. Evidence-based practice attitudes were assessed using the Evidence-Based Practice Attitude Scale-50 with appropriate modifications for optometry. Workshop design incorporated strategies to trigger discussion among participants. A nominal group technique was used to identify, prioritize, and reach consensus on barriers to EBP. Results Although some participants expressed reservations about EBP, a common understanding of the contemporary definition of EBP emerged in educators. Thirty-five barriers to EBP were identified; “time” was selected in the top five barriers by most participants and attracted the highest total score, well above any other barrier (negative attitude to EBP, volume of evidence, integration with clinical practice, and lack of lifelong learning mind-set). Attitudes toward EBP were generally positive and negatively correlated with age and time since graduation, respectively. Conclusions A group of optometrists and academics new to implementing education in EBP displayed positive attitudes to EBP but considered that its application and teaching could be significantly hindered by a lack of time to access and appraise the large volume of available research evidence in the field of eye care.

Impact of supervised student optometry consultations on the patient experience

Understanding patient perceptions of having students involved in their clinical care is important as we strive to develop optimal models of care that integrate teaching with the best possible experience for the patient. The aim was to ascertain the impact of supervised optometry student consultations on the patient experience.

Optical treatment of amblyopia: a systematic review and meta-analysis: Optical treatment of amblyopia

Despite evidence that amblyopia can often be treated by optical treatment alone, many practitioners still do not use an optical‐correction‐only phase in amblyopia treatment and some investigators omit this important step in their research. This paper aims to systematically review the evidence for the optical treatment of strabismic, refractive and combined‐mechanism amblyopia and to quantify the evidence via a meta‐analysis.

The Effects of Vertical Yoked Prism on Horizontal Heterophoria

Purpose Vertical yoked prisms (VYPs) have been recommended for the remediation of vergence dysfunction, but the evidence base for their use is mostly low level. This study investigates the effect of VYP on horizontal subjective dissociated heterophoria. Methods Phoria measurement was performed in primary gaze with the Modified Thorington technique at 3 m and at 40 cm on 40 nonpresbyopic young adults. Subjects were seated and head position was held constant. Baseline measures (without yoked prism) of distance and near phoria were measured. Phorias were measured again through the following range of VYP, randomly presented: 2 prism diopters (&Dgr;) base up (BU), 2&Dgr; base down (BD), 5&Dgr; BU, and 5&Dgr; BD. Twenty-six subjects also had their phorias measured with control lenses of +0.125 DS OU (because of unavailability of Plano trial lenses) randomly presented along the other conditions. Results There was no significant difference overall between phoria measured in any of the yoked prism conditions, including the baseline measure, at distance or near. Neither was there evidence of a predictable esophoric or exophoric shift with either BU or BD prism. Conclusions Vertical yoked prisms did not exert any immediate effect on horizontal phoria in young adults when posture was controlled. This suggests that, if VYPs do indeed improve horizontal vergence problems, they do not do so by a direct or immediate impact on horizontal phoria.