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Vision-Related Activities and Quality of Life in Glaucoma
December 2015
Ekici et al. examined the relationships between clinical visual assessments, vision-related performance (VRP), and subjective vision-related quality of life (VRQoL) in a large, prospective cohort study. The strongest correlation they found was between contrast sensitivity and the ability to perform vision-related activities.
The researchers studied 161 patients with moderate-stage glaucoma recruited from May 2012 to May 2014 in an ongoing prospective, 4-year longitudinal observational study. This report includes cross-sectional results from the baseline visit. Patients received a complete ocular examination, automated visual field (VF) test, and an optical coherence tomographic scan. Contrast sensitivity was measured with the Pelli-Robson and the Spaeth-Richman Contrast Sensitivity (SPARCS) tests. VRP was determined by the Compressed Assessment of Ability Related to Vision (CAARV) test. VRQoL was assessed by the National Eye Institute Visual Function Questionnaire 25 and a modified Glaucoma Symptom Scale (MGSS).
The strongest correlation was found between SPARCS score in the better eye and total CAARV score. The CAARV score also correlated with the Pelli-Robson score, VF mean deviation, and visual acuity (VA) in the better eye. There were more correlations between contrast sensitivity tests and VF mean deviation with VRQoL measurements than with other clinical measures (VA, intraocular pressure, Disc Damage Likelihood Scale, and mean retinal nerve fiber layer [RNFL] thickness). The MGSS scores were lower (worse) in women compared with men (p = .01 for the better eye, p = .05 for the worse eye, and p = .03 for both eyes). Structural measures such as RNFL thickness were generally not informative with respect to VRP or VRQoL.
The authors concluded that contrast sensitivity tests and VF mean deviation were associated with both objective measures of the ability to act and subjective measurements of VRQoL. The strongest correlation was between the SPARCS score (contrast sensitivity) in the better eye and total CAARV score. The authors noted that the results of this study were limited by the patient population and apply only within the bounds of the tested cohort.
Myopia, Birth Order, and Educational Exposure
December 2015
Visual impairment due to myopia is an important public health issue. A prior analysis of population-based cohorts aged 15 to 22 years had found that myopia and high myopia were approximately 10% more common in first-born compared with later-born children. Guggenheim et al. examined whether that association was also present in an earlier generation and, if so, whether it was attenuated after adjusting for educational exposure. The latter question was based on the hypothesis that there was less parental investment in the education of later-born children.
The researchers evaluated a cross-sectional study of United Kingdom Biobank participants recruited from 2006 to 2010. Analysis was restricted to participants aged 40 to 69 years who had a vision assessment, self-reported white ethnicity, and no history of eye disorders (n = 89,120). Myopia and high myopia were defined as autorefraction of −0.75 D or less and −6.00 D or less, respectively.
Two models were used to analyze odds ratios (ORs) for myopia and high myopia by birth order using logistic regression and adjusting for age and sex (model 1) or adjusting for age, sex, and highest educational level (model 2). In model 1, birth order was associated with both myopia and high myopia. The risk for myopia became progressively lower for later birth orders, suggesting a dose response. In model 2 (adjusted for education), the effect sizes were attenuated by approximately 25% for both myopia and high myopia, and the apparent dose response for successive births was no longer seen.
These data suggest that the association between birth order and myopia is not due to a new environmental factor in the last 30 to 40 years. The attenuated effect size after adjustment for educational exposure supports the concept of reduced parental investment in education of children with later birth orders, conferring a relative protection from myopia.
3-D Graphical Method for Displaying IOL Calculations
December 2015
Calculating the most accurate power of the intraocular lens (IOL) is a critical factor in optimizing patient outcomes after cataract surgery. Ladas et al. developed a graphical method for displaying IOL calculation formulas in 3 dimensions, and they describe how they incorporated information from several existing IOL formulas to create a “super formula.”
They used a numerical computing environment to create 3-D renderings, or “surfaces,” of the Hoffer Q, Holladay I, Holladay I with Koch adjustment, Haigis, and SRK/T formulas. These surfaces then were analyzed to determine where the IOL powers calculated by each formula differed by more than 0.5, 1.0, and 1.5 D. Next, a “super surface” was rendered that incorporated the ideal portions from 4 of the 5 formulas to generate a super formula. Last, IOL power values for a set of 100 eyes from consecutive patients at an eye institute were calculated using the 5 formulas and the super formula.
In these eyes, the super formula localized to the correct portion of the super surface 100% of the time and thus chose the most appropriate IOL power. The individual formulas deviated from the optimal super formula IOL power values by more than 0.5 D 30% of the time with Hoffer Q, 16% with Holladay I, 22% with Holladay I with Koch adjustment, 48% with Haigis, and 24% with SRK/T. The authors concluded that their method represents IOL formulas in 3 dimensions. Further, they state that the IOL super formula incorporates the ideal segments from each of the existing formulas and provides an algorithm for choosing the optimal IOL formula for an individual eye. The authors suggest that this method may broaden the conceptual understanding of IOL calculations and stimulate further research.
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JAMA Ophthalmology summaries are based on authors’ abstracts, as edited by senior editor(s).
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