IN THIS ISSUE:
Prentice Would be Proud!
Our 2012 Prentice Medalist takes a modern look at the Prentice legacy by noting that wavefront aberrometry is a 21st-century technology changing both our way of thinking about the eye as an imaging system and the measurement of its optical flaws. Thibos reviews the basic optical concepts underlying the clinical application of wavefront technology to many aspects of optometric practice. He makes a fascinating connection to Charles Prentice, generally considered the “Father of Optometry”, and his insights over 100 years ago. Thibos connects these insights to the revolutionary modern optics of the 21st century. Readers are treated to the video of the entire lecture, with a written transcript for the hearing impaired. Download onto your iPad. (p. 911)
Editor’s Choice open access
Solving the Power Mystery of Contact Lenses on the Eye
The authors compared the on-eye and off-eye optics of soft contact lenses. Sphere power measured in a wet cell closely matches lens specifications, but on-eye power can be significantly different because some lenses do not completely conform to the eye. The authors found that spherical aberration varied with sphere power as predicted by optical theory, but spherical aberration levels varied between lens designs and can change when placed on the eye. (p. 924)
Microbial Keratitis: What’s the Fuss?
Our authors provide a context for the risks of microbial keratitis (MK) with overnight contact lens wear, whether it be in overnight corneal reshaping or other overnight modalities. In their retrospective study, they estimate the incidence of MK associated with wearing overnight corneal reshaping contact lenses. Two cases of MK were identified in a sample of 1317 patients representing 2599 patient years of wear, but neither resulted in a loss of visual acuity. The risk of microbial keratitis with overnight corneal reshaping contact lenses appears similar to that with other overnight modalities. (p. 937)
Comfort Compared with Hydrogel Daily Disposable Contact Lenses
The authors’ study evaluated the ocular comfort in 104 subjects who wore three silicone hydrogel daily disposable lenses (DAILIES TOTAL1 [DT1], 1-DAY ACUVUE TRUEYE [AVTE], and Clariti 1 day [C1D]). All three silicone hydrogel daily disposable lenses performed well; however, comfort over the first 12 hours was highest with DT1 (similar to AVTE between 8 and 12 hours) and lowest with C1D. Comfort at the end of the day was lowest with C1D. This study used a new metric known as “cumulative comfort” to assess ocular comfort over the day, and with this metric the cumulative comfort was highest for the DT1 lens. (p. 945)
Mechanical Pressure or Hypoxia Responsible for Corneal Sensitivity Loss?
It is not clear what the relative contributions of hypoxia and mechanical force are to changes in corneal sensitivity during contact lens wear. Our authors provide some indirect evidence that mechanical force from contact lenses may be the key player. They deduce this from their finding of reduced sensitivity of the cornea after a single night of orthokeratology lens wear. All lens types in the comparative study had the same oxygen permeability, though only the OK lenses, with a different pressure on the cornea, showed significant corneal sensitivity change. (p. 954)
Discontinuation of Silicon Hydrogel Contact Lenses in Chinese Children
In our authors’ study of Chinese children aged 7 to 14 years, discontinuation of daily-wear silicone hydrogel contact lenses over a 2-year period was about 30%. There were less than 15% adverse events (mainly mechanically driven events), but none resulted in any visual loss. A significant percent of all those discontinuing daily wear did so in the first month of lens wear. (p. 961)
Was Rembrandt Strabismic?
Probably not, say our authors. A previous report claimed, based on asymmetric iris placement in Rembrandt’s self-portraits, that he was strabismic. Our authors studied this and conclude that the effect of head turn, angle kappa, and painting oneself using a mirror can result in enough asymmetry in iris placement to give the appearance of strabismus. Also, Rembrandt’s studio painted other portraits with a strabismic appearance, so some of Rembrandt’s apparent strabismus may have been due to artistic style. (p. 970)
Do Eye Movements Influence Myopia Development?
Apparently not, say our authors. They could find no difference in saccadic eye movements of emmetropes and myopes. Furthermore, when analyzing the emmetropic group alone, none of the saccadic eye movement parameters they measured were correlated with axial length or refractive error. (p. 980)
Mismatch of Signs and Symptoms For Convergence Insufficiency Severity?
Convergence insufficiency (CI) is a common binocular vision disorder that is often associated with symptoms while reading or performing close work. While previous studies show a positive correlation between the clinical signs (receded near point of convergence, exophoria at near, and insufficient positive fusional vergence) and symptoms, our authors found no relationship between symptom level and severity of each clinical sign (mild, moderate, and severe) among children with all three signs of CI. (p. 988)
Age-Based Design Needed for Intraocular Lenses?
The authors conducted a prospective observational study of 300 eyes of 167 patients and characterized changes in monochromatic higher-order aberrations that occur in the aging eye. They found a strong correlation for these aberrations with increasing age, as well as the expected correlation between eyes. The age changes in these aberrations occur within the eye and not at the cornea. They propose the use of an age-adjusted aspherical intraocular lens to counteract a non–age-changing corneal spherical aberration. (p. 996)
Targeting Vision Screening Programs
The authors conducted a retrospective review of 840 vision screening forms from a screening program in Omaha, Nebraska. They found that female gender, age older than 65, African American or Hispanic ethnicity, glaucoma diagnosis, and persistent eye pain were significant risk factors for failing a vision screening test. They argue that a focus on identified risk factors and chronic conditions, such as diabetes, as well as developing targeted vision screening programs, can improve vision health. (p. 1004)
Conjunctivitis and Refractive Error Problems for Squatter Settlement Children
In a first study of vision and eye problems in the overcrowded squatter settlements along the riverbanks in Kathmandu valley, the authors found ocular infection and refractive error represents the most common ocular morbidity in children. In the settlements, which lack sanitation and drinking water, they made a cross-sectional and community-based five-settlement study of 366 children among the 3502 children up to 14 years of age who live in the 45 squatter settlements in Kathmandu valley. (p. 1012)
Overweight Not a Risk Factor for Cataract in Korea
Being overweight is usually considered a risk factor for cataract formation, but the authors found low prevalence of cataract in overweight Koreans. Because the authors could not discover any other unusual points among anthropometric characteristics, lifestyle, and blood level (e.g., glucose, insulin, and cholesterols) in the overweight group, they suggest that some nutrients (e.g., vitamin B2) might play a beneficial role in the inhibition of cataract. They call for more studies in other populations. (p. 1019)
Surprising Treatment Results Suggests New Paradigm
Multiple myeloma is the most common plasma cell tumor; however, ocular plasmacytomas are rare and only a few cases of binocular metastasis have been reported. Our authors present a case study using intraocular bevacizumab to treat secondary glaucoma to binocular plasmacytoma. Surprisingly, intravitreal bevacizumab injection also inhibited ocular metastasis suggesting, to the authors, a promising treatment for ocular metastases. (p. e236)
Keratoplasty Feasible Even in Presence of Glaucoma Implants
In recent years, Descemet membrane endothelial keratoplasty (DMEK) is replacing full-thickness penetrating keratoplasty for the treatment of corneal endothelial disorders. However, it has been unclear whether DMEK is feasible in eyes with glaucoma implants. Our authors’ two case studies suggest that it is feasible even in their complicated cases. (p. e241)
Latanoprost-Induced Prostaglandin-Associated Periorbitopathy
Bimatoprost, travoprost, and latanoprost are prostaglandin F2-alpha analogues for glaucoma treatment. The authors report three cases, with supporting photodocumentation, of latanoprost users developing deepening of the upper eyelid sulcus, blepharoptosis, and enopthalmos. Because latanoprost is so widely prescribed in glaucoma treatment, our authors suggest that it is imperative for eye doctors to be aware of this side effect. (p. e245)
Seeking Guidelines for Scleral Lens Fitting in Successful Dry Eye Patients
Scleral contact lenses are used to treat symptoms of severe dry eyes, but fitting procedures are not standardized. Our authors’ retrospective case series sought to establish average vault over central cornea, using anterior segment optical coherence tomography, in successful scleral lens wearers with dry eye. They report, from a study of 20 eyes in 12 consecutive patients, that the variability of the vault over the central cornea was large enough to preclude application of vault dimension in any useful dry eye guidelines for these lenses. (p. e248)