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Research Update

Welcome to our monthly Research Update, available exclusively to IACLE and BCLA members to support your teaching and practice.

Issue 33 – September 2019

This time, in myopia control, we look at two relatively less discussed aspects.

Eye shape has been receiving increasing attention as a possible biomarker for myopia. A review paper discusses recent findings on eye shape changes in myopic eyes. Another study examines the role of dietary factors in myopia and a systematic review evaluates the effects of outdoor light exposure on myopia. 

We include a study that investigates the effect of soft contact lens wear on the morphology of the epithelial‐lamina propria junction of the conjunctiva, observed by confocal microscopy. A team from Hong Kong tests the effectiveness of RGP lens care solutions against biofilm. American researchers analyze the patterns of contact lens-related and non-lens related corneal ulcers. And finally, we include an international survey of orthokeratology lens fitting. 

Happy reading!

The IACLE Education Team

JOURNALS
Journals reviewed in this issue:
 
Eye & Contact Lens: 45:5  
Optometry and Vision Science: 96:9
International Journal of Environmental Research & Public Health: 16:4
Ophthalmic & Physiological Optics: 39:5
Contact Lens & Anterior Eye: 42:4
 
MYOPIA

Eye shape and myopia

Matsumura et al review recent findings on eye shape changes in myopic eyes and abnormal eye shapes in pathologic myopia. Shape change of non-myopic eyes follows the global expansion model while that of myopic eyes follows the axial elongation model. Abnormal eye shape changes can cause not only simple myopia but also ocular complications through biomechanical stretching. Eyes with pathologic myopia have abnormal and complex irregular curvatures of the posterior segment, such as staphyloma and dome-shaped macula.

Eye & Contact Lens 2019;45:5 279-285. Read the full text

Dietary zinc intake and myopia

To test the hypothesis that low zinc intake may be associated with myopia, Burke et al enrolled 1,095 children/adolescents aged 12 to 19 years who participated in the US National Health and Nutrition Examination Survey 2007-2008. The relationship between total zinc intake and myopia after adjustment for potential confounders was examined. In contrast to previous Asian studies, total zinc intake was not associated with the presence of myopia.

Optom Vis Sci 2019;96:9 647-654. Read the abstract

Outdoor exposure and myopia: a systematic review

To evaluate the effects of outdoor light exposure on myopia, Ciao-Lin Ho et al conducted a systematic review and meta-analysis including data from 13 studies of 15,081 children aged 4-14 years at baseline. Outdoor light exposure slows myopic progression in myopes. Outdoor intervention programs can significantly reduce myopia incidence by about 50%, slow myopic spherical equivalent refractive error progression by 33% and axial elongation by 25% for individuals in Asia. Daily outdoor light exposure of more than 120 min was the most effective intervention, and weekly intervention time showed a dose-response relationship with all three indicators. Combining outdoor light exposure during recess time and one additional hour of outdoor light exposure after school was most effective.

Int J Environ Res Public Health 2019;16:4 E2595. doi:10.3390/ijerph16142595. Read the full text

OCULAR SURFACE

Conjunctival morphology, soft CLs & ocular symptoms

To investigate the effect of soft contact lens (CL) wear on the morphology of the epitheliallamina propria junction and a possible association with discomfort, Lópezde la Rosa et al recruited 92 subjects (soft CL wearers, previous wearers and non-wearers). Confocal microscopy of the tarsal conjunctiva evaluated the morphology of papillae. Both soft CL wear and the presence of ocular symptoms were associated with morphological alterations to the epitheliallamina propria junction in the form of a more rounded papillae shape.

Ophthalmic Physiol Opt 2019;39:5 328-336. Read the abstract

LENS CARE

Evaluation of biofilm in contact lens cases

Cho & Boost evaluated the effectiveness of solutions for rigid contact lenses in prevention and disruption of biofilm in lens cases, and methods for biofilm detection. Four disinfecting solutions, three lens case designs and three organisms were included for testing. Solutions tested were revealed to have varying degree of effectiveness on biofilm survival. None was able to prevent biofilm formation or disrupt established biofilm, but those containing chlorhexidine or povidone iodine were able to penetrate the biofilm and kill organisms.

Ophthalmic Physiol Opt 2019;39:5 337-349. Read the abstract

INFECTIONS

Contact lens versus non-contact lens related corneal ulcers

To compare infectious contact lens-related corneal ulcer (CLRU) and non-CLRU cases, Bennett et al retrospectively analyzed 677 identified cases of corneal ulcers at an academic center. Less than half (46%) of the cases were CLRU. CLRU cases were seen more commonly in younger patients and women than non-CLRU cases. CLRU was disproportionately associated with Pseudomonas species and non-CLRU with Staphylococcal species. Acanthamoeba keratitis was exclusively associated with CL use.

Eye & Contact Lens 2019;45:5 301-305. Read the abstract

ORTHOKERATOLOGY

International survey of OrthoK lens fitting

Morgan et al report the extent of orthokeratology (OK) contact lens fitting worldwide along with associated demographics and fitting patterns. Data were obtained for 295,044 contact lens fits, of which 2,702 were with OK lenses from 45 countries over 14 consecutive years. There has been a slight overall increase in OK lens fitting over the survey period. Typically, OK lenses are fitted in high-Dk materials on a planned replacement basis to younger patients, presumably for the primary purpose of arresting the progression of myopia.

Cont Lens Anterior Eye 2019;42:4 450-454. Read the full text 

© International Association of Contact Lens Educators 2019

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