IN THIS ISSUE:
Corneal Inflammatory Events with Daily Silicone Hydrogel Contact Lenses?
In a 12-month study, 200 participants allowed our authors to conclude the probability and risk factors for development of a corneal inflammatory event (CIE) during daily wear of lotrafilcon A silicone hydrogel contact lenses had an unadjusted cumulative incidence of just over 7%. But the incidence of symptomatic CIEs was just under 2%. Normal flora in substantial numbers on the lid margins was associated with about a 5-fold increased risk of a CIE. The authors conclude the probability of experiencing a CIE during daily wear of lotrafilcon A contact lenses is low, symptomatic CIEs are rare, and patient factors such as high levels of bacterial bioburden on lid margins contribute to the development of CIEs. (p. 3)
Editor’s Choice open access
Do Antibiotic Drugs Lower Inflammation with Continuous Wear CL?
Our authors’ “proof of principle” study using twice-daily antibiotic instillation did not significantly influence rate of inflammatory events during a 30-day continuous wear schedule. As expected, higher levels of contamination were recorded even with a low level of complications. (p. 13)
Can CL Comfort be Increased with Lens Changes During the Day?
Final end-of-day comfort did not increase after a 10-hour wearing day despite fresh contact lens changes midway through the day. The authors suggest possible etiological factors include a fatigue-like response in one or more ocular tissues, or stimulation of ocular surface nociceptors induced by the presence of the contact lens induces end of day discomfort. (p. 24)
Impact of Hyaluronic Acid in Ophthalmic Products
Hyaluronic acid (HA) is a natural lubricant and moisture absorber that is found throughout the eye. Previous research has suggested that there is a correlation between the molecular weight of HA and its biocompatibility/biological functions with high molecular weight HA exhibiting more biological benefits. Our authors’ study found a wide range of HA molecular weights and concentrations in 11 marketed ophthalmic products. They say that more research may be warranted to better understand the clinical and biological implications of the molecular weights and concentrations of HA in ophthalmic products. (p. 32)
A Safe and Effective Dose of Sodium Hyaluronate for Dry Eyes
Our authors concluded that 0.18% sodium hyaluronate eye drops were not only effective in relieving symptoms in patients with moderate to severe dry eye but did not affect the higher-order aberrations of coma or spherical aberration. (p. 39)
How Well Does Culture of Contact Lenses Reflect Corneal Cultures for Microbial Keratitis?
Using microbial investigations and positive cornea cultures in suspected infectious keratitis cases associated with contact lens wear between January 2001 and November 2011, our authors found the same microbes in 94% of contaminated contact lens cases and cornea cultures and corneal cultures correlated with the same microbes in 77% of contaminated cases. This result suggests that contact lens cultures might be an effective test to detect the causative microorganism when corneal cultures are unavailable. Interestingly, Pseudomonas aeruginosa was the predominant organism isolated. (p. 47)
Ocular Pulse Change with Age a Potential Early Cardiovascular Disease Indicator?
Corneal expansion, defined as the ocular pulse, is primarily caused by choroidal blood volume pulsation and the natural variations in the intraocular pressure. Pathological alterations in ocular blood supply are associated with corresponding changes in the form of the ocular pulse signal.
Our authors study age-related changes in the shape of the ocular pulse in relation to simultaneously registered blood pulsation and electrocardiogram signals in healthy subjects. About 70% of older subjects, and none of the younger subjects, showed evidence of ocular pulse dicrotism (double peak), which could be a natural sign of aging or an early indication of vascular disease. This ocular pulse dicrotism has been not been observed previously. If related to cardiovascular disease, it could become a noninvasive window to early diagnosis. (p. 54)
Refractive Error Differences Between the Two Eyes Much Higher in Older Adults
In a study of the same patients over a 12-year period, significant refractive error differences between the eyes (anisometropia) is shown to be 10 times greater in the over 80 age group (32%) than in children (3%). Uncorrected anisometropia is likely to lead to disturbances in depth perception, which in turn may contribute to disturbing and dangerous falls in the elderly. It also suggests that “over-the-counter readers”, which always have the same prescription in each eye, may be a very imperfect solution for many older people. Most of these differences between the eyes are likely a result of differences in aging changes in the crystalline lens in each eye. (p. 54)
Ocular Aberrations in Rural Chinese Adults
The authors investigated the effect of monochromatic aberrations on refraction of 404 rural Chinese adults who grew up in villages and did farm work during their lives. The refraction of the adults became more hyperopic with age. Their higher-order optical aberrations were similar to that of other ethnic populations and significantly increased with age. However, no differences in these aberrations were found among myopic, emmetropic, and hyperopic adults after adjusting for age. These findings suggest that higher-order optical aberrations are not sufficient to account for the myopia epidemic in China. (p. 68)
A New Acuity Test: Testability, Validity and Inter-Observer Reliability
The Pacific Acuity Test is a new vanishing optotype acuity test that employs two figures in a forced-choice format to measure recognition acuities with preverbal children. In a sample of children age 6-36 months, our authors found a transition from relatively low to high testability at 16-22 months using this dual-optotype strategy. This study should help clinicians to examine young children and individuals with disabilities. Further research is needed to evaluate the accuracy of the test for children with amblyopia or pathological visual deficits. (p. 76)
Improving Reading for Patients with Central Vision Loss
With training sessions of 10 blocks of 100 words in a session using binocular presentations at threshold level reading acuity, the authors discouraged letter-by-letter reading and timed each session. The group of 10 patients improved binocular acuity with each session and after 10 sessions improved one line of acuity (0.1 logMAR). Furthermore, they noted improvement in continuous text reading and 60% improvement in fixation stability in each eye. They suggest the use of their technique for vision rehabilitation of low-vision patients. (p. 86)
Magnification Equations Applied to New Environments
Spectacle magnification was determined for ophthalmic lenses in air and for water environments. The reference was the retinal image for an uncorrected eye in air with a natural pupil. The authors developed equations showing the spectacle magnification when the limiting stop is either the entrance pupil of the eye or an artificial pupil at the front of a lens. When an artificial pupil is placed at the front of lenses, spectacle magnification is hardly affected by lens power. In water, spectacle magnification is highly sensitive to the distance between the cornea and eye entrance pupil. (p. 97)
Perception of “Up” is Resistant to Blur
Orientation in the environment is important for many aspects of our vision including recognizing objects, planning our actions, our balance, and our navigation. The authors studied the effect of blur on the perception of self-orientation by measuring the impact of tilted cues on the perceived visual vertical and perceptual upright. Visual cues to self-orientation remained effective until vision was degraded to about 20/240. They conclude that tasks that require knowledge of self-orientation with uncorrected refractive errors of greater than about 2D may be more hazardous than expected. (p. 103)
Post–Laser-Treatment Visual Field Improvement in Severe Diabetic Retinopathy
The authors’ study reveals how the patterns of central visual field loss seen in untreated proliferative diabetic retinopathy change when the eye is treated with low-dose retinal laser. Post-treatment, the majority of patients showed a regression of their retinopathy and an improvement in their central visual field. Visual field improvements occurred to both the spatial pattern of loss and to the global indices of Mean Deviation and Pattern Deviation. Improvements in the visual field were largest in eyes with more severe loss. (p. 111)
Acting Improves Student-Patient Communication Skills
Using mock clinical encounters with patient actors, our authors found that educational enrichment, in the form of immediate instructor feedback, combined with viewing of videotaped sessions, improved student-patient communication skills. These mock patient encounters provided a low-risk environment for training student clinicians in patient communication skills, allowing them to gain experience with challenging scenarios that are critical for practical competency. (p. 121)
iPhone for Tear Film Evaluation?
Our authors developed a novel application for an iPod or iPhone that created an illuminated target of parallel black and white bands. Their new portable digital meniscometer was used as a noninvasive method to measure the tear meniscus radius, useful in dry eye diagnosis. They found their instrument was accurate and reliable, and was able to provide similar values for tear meniscus radius, in human studies, to the existing video-meniscometer. The instrument appears suitable for a general use of meniscometry in both research and clinical practice. (p. e1)
New Approach to Imaging the Retina
The authors report on an innovative imaging technique to obtain near-infrared autofluorescence images using simultaneous fluorescein angiography + indocyanine green angiography (FA + ICGA) acquisition mode without dye injection, of Spectralis HRA + OCT (Heidelberg Retina Angiograph). They set the maximum level of illuminance and Automatic Real Time Module (ART) to increase signal-to-noise ratio. This combined scanning laser ophthalmoscope technique is a simple trick that the authors suggest allows the Spectralis HRA + OCT device to create high-quality NIA ART images without requiring a separate HRA2 device. (p. e9)
Genetic Testing After Radiation: A Future Direction Suggested?
The authors present three novel cases where genetic analysis was successfully obtained from uveal melanoma that was previously treated years earlier with radiotherapy. This small case series is the first to utilize genetic expression profiling years after radiation treatment has been successfully performed. Because genetic testing was performed for these patients before radiation treatment, the generalizability of these results will benefit from ongoing clinical evaluation. (p. e14)
New Imaging Makes for Successful Treatment of Corneal Abrasion
This case report demonstrates the use of in vivo corneal confocal microscopy to reveal the reason for persistent disturbance of vision after a traumatic corneal abrasion. The authors were not able to detect the pathology using the corneal OCT. But using in vivo corneal confocal microscopy, they found a structural abnormality and successfully treated the epithelial corneal layers of the affected area. These findings suggested another treatment was called for; they successfully used therapeutic abrasion of the epithelial layers in the affected area. Their findings suggest an vivo corneal confocal microscopy can reveal corneal pathology even in case of only fine structure changes where other methods are not beneficial. (p. e18)