German investigators examined whether optic disc hemorrhages (ODH) lead to significant loss of nerve fibers at the lesion site over time and whether such a loss is reflected by visual field defects corresponding to the affected nerve fiber bundle.

In this retrospective study of 10 sequential glaucoma patients (ten eyes) with ODH, they used high-resolution OCT circular scans (Spectralis HRA + OCT) to determine peripapillary retinal nerve fiber layer (RNFL) thickness at the time of ODH presentation and at follow-up visit between 3 and 6 months. They also analyzed corresponding perimetric data for global (mean defect, MD) and localized progression of visual field defects.

According to the investigators, ODH were mostly located in the inferior quadrant as determined clinically and from fundus photographs. They also reported that iterative OCT imaging revealed a significant RNFL reduction in the affected quadrant relative to the respective quadrant in the fellow eye (RNFL change = –2.25 ± 2.69 µm vs. 0.75 ± 2.78 µm, p = 0.01) within 120 ± 43 days. However, only three cases presented with new/progressive nerve fiber bundle defects corresponding to the lesion site within the given follow-up period.

To conclude, ODH lead to a significantly higher RNFL loss at the lesion site relative to the overall structural progression in glaucoma patients. However, this focal change is not generally reflected by respective nerve fiber bundle defects in the time frame investigated.

The authors of the following Chinese study sought to differentiate the associations of exudative age-related macular degeneration (AMD) and polypoidal choroidal vasculopathy (PCV) with the ARMS2/HTRA1 locus. They found a strong and consistent association of the ARMS2/HTRA1 locus with both exudative AMD and PCV, suggesting the two disorders share, at least partially, similar molecular mechanisms.

They sequenced the entire ARMS2 sequence and genotyped HTRA1 rs11200638 in 568 unrelated Chinese individuals: 156 exudative AMD patients, 164 PCV patients and 248 controls. The authors also performed a meta-analysis to examine the effects of rs10490924 and rs11200638 at the ARMS2/HTRA1 locus in PCV.

In total, they identified 31 polymorphisms in ARMS2. They also observed significant associations with both exudative AMD and PCV in 11 of them and HTRA1 rs11200638, with different genotypic distributions between exudative AMD and PCV (p<0.001). The study authors reported that after adjusting for rs11200638, ARMS2 rs10490924 remained significantly associated with exudative AMD (p=0.011), but not with PCV (p=0.077). Moreover, meta-analysis showed consistent allelic associations of rs10490924 and rs11200638 with PCV in different study populations.

In conclusion, different effect sizes indicate the existence of additional genetic and environmental factors affecting them to different extents.

Researchers aimed to explore the relationship of sleep apnea and the subsequent development of retinal vein occlusion (RVO). They conducted a retrospective nonrandomized, matched-control cohort study using the Taiwan National Health Insurance Research Database and found that sleep apnea may be an independent risk factor for RVO.

From 1997 through 2007, they identified newly diagnosed sleep apnea cases in the database and selected a control group without sleep apnea, matched for age, gender and comorbidities, for comparison. Additionally, they followed the 2 cohorts and observed and the occurrence of RVO.

The researchers noted that of the 35,634 sampled patients (5,965 sleep apnea patients vs 29,669 controls), 52 (0.15%) experienced RVO during a mean follow-up period of 3.72 years, including 13 (0.22%, all branch RVO) from the sleep apnea cohort and 39 (0.13%, 39 branch RVO and 10 central RVO) from the control group. Kaplan-Meier analysis revealed the tendency of sleep apnea patients toward RVO development (p = .048, log-rank test). Furthermore, patients with sleep apnea experienced a 1.94-fold increase (95% confidence interval, 1.03 to 3.65; p = .041) in incident RVO, which was independent of age, gender and comorbidities.

In ophthalmic randomized controlled trials (RCTs), each subject may have 2 potential data points (i.e., eyes) contributing to the clinical trial; therefore, various study designs may arise requiring different statistical tools. This study aimed to assess the appropriateness of study design, statistical tools used and reporting of results in ophthalmic RCTs.

In this systematic review of 69 ophthalmic RCTs published in 4 major general clinical ophthalmology journals in 2009, the study design, sample size calculation, statistical analysis and reporting methodology of all RCTs were assessed. For the main outcome measure, the study design of each article under review is evaluated.

The most common study design was a one-eye design (48%). Within this group, only half described the method of selecting the study eye, among which 5 chose the study eye by random selection. In the remaining trials, there were paired-eye design (13%), subject design (19%) and two-eye design (19%). Among the 13 two-eye design studies, 4 allocated both eyes of the subject to the same group, 4 allocated the eyes to different groups, and 4 did not restrict the allocation. None of these studies adjusted for the clustering effect in sample size calculation. Only 5 studies used statistical methods adjusting for nonindependence.

There is currently substantial heterogeneity in the quality among published ophthalmic RCTs in terms of proper use of study design, sample size calculation, randomization method and statistical tools. Future ophthalmic researchers are suggested to consult a statistician and to follow some guidelines such as the CONSORT statement when performing an RCT to improve further the quality of clinical trial.