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Treatment Effect and Corneal Light Scattering in 2 CXL Regimens
November JAMA Ophthalmology
In order to indirectly quantify the treatment effect of corneal cross-linking (CXL), Rehnman et al. assessed the spatial distribution and time course of the increased corneal densitometry (measured by corneal light backscatter) seen after CXL. They concluded that the degree of backscatter relates to the reduction in corneal steepness and could be helpful in evaluating the effect of CXL.
This open-label randomized clinical trial included 43 patients (60 eyes), aged 18 to 28 years, who had progressive keratoconus and were treated with CXL at a university hospital in Sweden. The eyes were randomized to receive conventional CXL (n = 30) using the Dresden protocol or CXL with mechanical compression of the cornea using a flat rigid contact lens sutured to the cornea during the treatment (CRXL; n = 30). Patients were treated and followed for a 6-month period between Oct. 13, 2009, and May 31, 2012.
The main outcome measures included change in corneal densitometry after conventional CXL and CRXL. A densitometry increase was seen after both treatments, but it was deeper and more pronounced in the conventional CXL group (difference between the groups at 1 month in the center layer, zone 0-2 mm, 5.02 grayscale units [GSU]; p < .001). This increase diminished with time but was still noticeable at 6 months (difference between the groups at 6 months, 3.47 GSU; p < .001) and was proportional to the reduction in corneal steepness (R = −0.45 and −0.56 for conventional CXL and CRXL, respectively).
The authors concluded that the amount of corneal light backscatter relates to the reduction in corneal steepness. It may be a useful complement to other methods to evaluate the effect of CXL, for example, in comparing different treatment regimens.
Vaccinations and Retinal Hemorrhage in Children
November JAMA Ophthalmology
Vaccinations have been proposed as a cause of retinal hemorrhage in children, primarily as part of a defense strategy in abusive head trauma cases. To investigate this issue, Binenbaum et al. conducted a retrospective cohort study on the prevalence and causes of retinal hemorrhage among infants and young children in an outpatient ophthalmology clinic setting. Only a very small number of retinal hemorrhages were found in this population, and all instances could be attributed to child abuse.
Participants were children aged 1 to 23 months old who had a dilated fundus examination between June 1, 2009, and August 30, 2012, at pediatric ophthalmology clinics in Philadelphia. (Children who had intraocular surgery or active retinal neovascularization were excluded.) In 7,675 outpatient fundus examinations of 5,177 participants, 9 children were found to have retinal hemorrhage, for a prevalence of 0.17%. All 9 had abusive head trauma diagnosable with nonocular findings.
The researchers also investigated possible temporal association between vaccination injection and retinal hemorrhage in a subset of 2,210 children who had complete immunization records available and who underwent 3,425 ophthalmoscopic examinations. In this subset, 163 children had an eye exam within 7 days of vaccination, 323 within 14 days, and 494 within 21 days. No children had retinal hemorrhage within 7 days of vaccination, 1 child had a hemorrhage within 14 days, and no additional child had hemorrhage within 21 days. No temporal association was found between vaccination injection and retinal hemorrhage in the prior 7, 14, or 21 days.
The authors found that retinal hemorrhage was rare among outpatients younger than 2 years, despite the frequency of vaccination in this age group. No temporal association, either immediate or delayed, was identified between vaccination and retinal hemorrhage. The authors concluded that no evidence supports the theory that vaccination causes retinal hemorrhage, and this notion should not be accepted clinically or in legal cases. They state that ophthalmologists who find an incidental retinal hemorrhage in the absence of known ocular or medical disease should consider a child abuse evaluation.
Exacerbation of Chronic Health Conditions by Visual Impairment
November JAMA Ophthalmology
Using data from the Korean National Health and Nutrition Examination Survey (KNHANES), Park et al. investigated the effect of visual impairment (VI) in combination with other chronic health conditions on health-related quality of life (HRQOL). They found that concurrent VI increased the negative impact of the conditions they studied on HRQOL.
KNHANES is an ongoing population-based, government-run, cross-sectional survey of randomly selected households in South Korea. The researchers analyzed data from 28,382 participants aged 19 years and older in the 2008-2012 survey whose records included measurements of both visual acuity (VA) and HRQOL. VI was defined as a distance best-corrected VA of less than decimal 0.32 (approximate Snellen equivalent 20/63). HRQOL was assessed using the European Quality of Life–5 Dimensions Questionnaire (EQ-5D).
Linear regression models were used to examine interactions between VI and each of 14 chronic health conditions on the EQ-5D score, adjusted for demographic and socioeconomic covariates. The EQ-5D index score for participants with VI was substantially lower than for those without VI (mean difference, −0.158; p < .001). When each of the chronic health conditions was stratified by VI, the index scores were lower with VI and the chronic health condition together than with the chronic health condition alone, with the exception of myocardial infarction/ischemic heart disease. In particular, participants with stroke, osteoarthritis/rheumatic arthritis, hepatitis B or C, or depression showed lower EQ-5D index scores than expected when they concurrently had VI, indicating an interaction between VI and each condition.
The results suggest that VI substantially exacerbates the effect on HRQOL of concurrent chronic health conditions. Further, the additive effect of VI on HRQOL was strongest in combination with stroke, osteoarthritis/rheumatic arthritis, hepatitis, or depression. However, because this study group consisted of South Koreans, generalization to other races/ethnicities and countries should be approached with caution.
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JAMA Ophthalmology summaries are based on the abstracts, as edited by senior editor(s).
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