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February 16, 2022


The most important ophthalmology research updates, delivered directly to you.
 

In this week's issue
  • Longitudinal cohort study shows RNFL and ganglion cell layer may correlate with cognitive decline 
  • Blue-light filtering IOLs did not increase rates of insomnia 
  • In a longitudinal five-year prospective cohort, color-deficient individuals had lower myopia incidence 

RNFL and Ganglion Cell Layer: Potential Biomarkers for Alzheimer’s Disease

JAMA Ophthalmology

Connections between cognition and vision could be more than just a synapse. Identifying biomarkers for early, preclinical Alzheimer’s disease (AD) is a growing field of research. With the help of biomarkers, researchers hope to recognize patients at risk of cognitive decline at a point where treatment may delay progression. Studies have shown that the retinal nerve fiber layer (RNFL) and ganglion cell layer (GCL) of patients with AD tends to be thinner than those without AD. However, these data are from patients with clinically significant AD. Little is known about RNFL and GCL thickness in patients with early cognitive changes. In a longitudinal cohort study of 865 patients sourced from a New Zealand database, researchers compared cognitive metrics at ages 7, 9, 11, and 45 with RNFL and GCL thickness measured at age 45. Cognitive metrics included Full Scale IQ (FSIQ), processing speed, perceptual reasoning, and verbal comprehension. Multivariable linear regression models showed lower FSIQ scores associated with thinner mean RNFL (Adult: B = 0.202, 95% CI 0.089-0.315; Child: B = 0.213, 95% CI 0.108-0.318) and GCL (Adult: B = 0.178, 95% CI 0.005-0.351; Child: B = 0.247, 95% CI 0.087-0.406) measurements. Reduction in processing speed from childhood to adulthood was associated with thinner RNFL measurements (B = 0.292, 95% CI 0.019-0.566) but not GCL measurements. Together, these results indicate that RNFL thickness may be a potentially useful biomarker for cognitive decline; however, progression to AD was not assessed. Additional work with RNFL measurements and cognitive assessments throughout life would elucidate whether RNFL changes precede cognitive decline. 

Blue-light filtering intraocular lenses: A cohort study

American Journal of Ophthalmology

You've heard of blue-light glasses, but have you heard of  blue-light filtering intraocular lenses? Some suggest that blue-light filtering glasses may improve the quality of sleep, while Blue-light filtering IOLs (BF-IOLS) may interfere with the circadian rhythm by blocking blue light constantly. A nationwide cohort study in Taiwan compared the incidence of clinically diagnosed insomnia after cataract surgery in those with vs. without BF-IOLS. It included 171,415 patients, with 19,604 (11.4%)  patients with BF-IOL implants and 151,811 (88.6%)  patients with non-BF-IOL implants. The patients were followed for up to 10 years, with a mean follow up period of 6 years. There was no significant difference in incidence rates of insomnia between the BF-IOL and non-BF-IOL groups ( 2.97 and 3.21 per 100 person-years, p=1.329). The key strength of this study was its size and duration; however, important limitations include non-randomized IOL groups and confounding factors that may also affect insomnia.

Relationship between color vision deficiency and myopia

IOVS

Besides having to turn on “color blind mode” on Wordle, are people living with color vision deficiency more or less likely to develop myopia? Emmetropization occurs during normal eye growth to allow for the eye to grow to match its retinal position with the image focal plane, matching its optical power to axial length. When images fall in front of the retina, this results in myopia or nearsightedness (cue the need for glasses, contacts, or refractive surgery!). Prior studies have shown that the emmetropization process is sensitive to chromatic cues which may cause different refractive statuses between people with color vision deficiency (CVD) versus normal color vision (CN). A longitudinal five-year prospective cohort study was conducted among primary school aged children in China to explore the relationship between CVD with myopia progression and axial elongation. Myopia incidence was lower in the color vision deficiency group (35.4%) compared to the color normal group (56.7%) as well as change in spherical equivalent refraction (-1.81 D in color vision deficiency vs. -2.41 D in color normal). While these results are limited to a particular geographic region and ethnic background, they provide unique insight into the lower incidence of myopia and slower myopic progression in people with color vision deficiencies. These differences could be due to altered cone ratios or cone contrast and more studies should be conducted to evaluate this relationship across broader age groups and racial populations.

Glaucoma

Anterior Angle Depth and Diagnostic Factors Associated with Angle Closure Disease

Journal of Glaucoma

Shallow anterior chamber angle depth (ACD) is a major risk factor for developing primary angle closure disease (PACD). However, not all patients progress to angle closure. Investigators sought to determine the difference between patients with ACD that do not progress to PACD to those who have similar angle measurements and do develop PACD through means of anterior chamber OCT. Comparing multiple parameters between the ACD and PACD groups, PACD was determined to be more associated with increased IOP (18.4 vs. 14.0 mm Hg, P=0.005). PACD was also more associated with specific angle parameters such as smaller angle recess area and trabecular iris space area (P<0.005) when measured at 250 um. These effects were not significant when measured at 500 and 750 μm. This cross-sectional study is novel in its unique findings in patients that develop PACD, however there is no evidence for causality or mechanism at this time.

Public Health

Impact of COVID-19 Restrictions on Retinal Detachment

Ophthalmology Retina

While non essential surgeries were temporarily ceased during the early phase of the COVID-19 pandemic, rhegmatogenous retinal detachment repair was conducted an emergency procedure. This retrospective multicenter cohort study analyzed practice patterns of vitreoretinal surgeons in North America less than 10 years out of training with regards to rhegmatogenous retinal detachment surgeries during and after the early COVID-19 lockdown period. Post lockdown characteristics were significant for less use of C3F8 vs SF6 (p=0.034) with PPV and pneumatic retinopexy more commonly utilized in patients with COVID-19. Longer time to repair and increased years of age were associated with higher rates of post operative proliferative vitreoretinopathy. Limitations included differences in surgical strategy among surgeons included as well as patients lost to follow up (particularly due to pandemic limitations). The effects of pandemic delays in surgical care deserve further study and attention to differences in patient outcomes.

Question of the Week
A 24-year-old male presents to the emergency department with bilateral severe eye pain that started a few hours after falling asleep. He also has a gritty sensation in his eyes, redness, and tearing. He is on vacation. The patient has not experienced anything like this in the past. His pupils are slightly miotic but he otherwise has normal visual acuity, pressure, motility, and confrontational visual fields. Slit lamp exam shows erythematous eyelids, bulbar conjunctival injection with sparing of palpebral conjunctiva, sluggishly reactive pupils, and a mild anterior chamber reaction. A fluorescein staining pattern of the cornea is shown below.
What is the most likely diagnosis?
 
A.     Dry eye syndrome
B.     Ultraviolet keratitis
C.     Cluster headache
D.     Viral conjunctivitis

 
Keep scrolling for answer or click here
 

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