January 18, 2022

The most important ophthalmology research updates, delivered directly to you.
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In this week's issue

  • The risk of acanthamoeba keratitis is significantly greater in daily wear contact lens users versus daily disposable contact lens users.
  • Research productivity prior to ophthalmology residency is significantly associated with research productivity during and after residency.
  • A new study discovers a significant association between certain medication use and need for cataract surgery.
  • Detection of circulating tumor DNA in uveal melanoma patients after plaque brachytherapy or enucleation may help predict risk of metastasis.

Acanthamoeba keratitis risk factors for daily wear contact lens users


Thinking about switching to daily disposable contact lenses? Here’s why you should. A new study significantly greater risk of Acanthamoeba Keratitis (AK) with soft, reusable daily wear (DW) lenses compared to single use daily disposable (DD) lenses. AK  associated with contact lens use results in vision loss for many patients and disproportionately higher costs. In this study, researchers performed a retrospective case-control analysis to compare risk factors for AK in different contact lens users. 83 AK cases and 122 controls were included. The risk of AK was 3x greater in DW users (OR=3.84) and 4x greater in rigid lens users (OR=4.56) compared to DD users. PAR% calculations suggest 30-62% of cases of AK can be prevented by switching to DD lens use. Further, AK was associated with modifiable risk factors in DD users such as lens reuse, showering in contacts, and overnight wear. Results from this study encourage more users to switch to DD lenses and current users to adhere to safe use guidelines. Given the prevalence of AK in this population, these measures can have significant public health benefits. 

Correlation between pre-residency publications and future research productivity

JAMA Ophthalmology

Publication count in residency applications – pass or fail? Research is an important aspect of ophthalmology residency applications and is expected to become even more so following the transition to pass/fail scoring for Step 1 of the United States Medical Licensing Examination. Despite its critical role in residency selection, little is known about the ability of pre-residency research to predict long-term academic productivity. To investigate this further, researchers searched PubMed for articles authored by any one of 964 ophthalmologists who graduated residency between 2013 and 2016. Articles for each ophthalmologist were classified as pre-, intra-, or post-residency. Analysis of these data showed a moderate, but significant, correlation between pre- and intra-residency publications (ρ = 0.38, 95% CI 0.32-0.43, P < 0.001), as well as pre- and post-residency publications (ρ = 0.26, 95% CI 0.20-0.31, P < 0.001). These results suggest that publications before residency training are at least somewhat predictive of research productivity during and after residency. It is worth noting, however, that these univariate analyses did not adjust for the extent of resources available to trainees in medical school or residency. Care should be exercised when considering the academic potential of those who trained in less research-oriented institutions, as their opportunities to engage in meaningful research may have been limited.

What drugs do ophthalmologists need to look out for in their cataract evaluation patients?

American Journal of Ophthalmology

Thought you could escape body medicine in ophthalmology? Think again! Cataracts are a leading cause of blindness worldwide however beyond steroid use, there is limited strong data on cataract development secondary to systemic medications. This retrospective, cross-sectional study analyzed 14,931 participants from the National Health and Nutrition Examination Survey (NHANES) data (1999-2008) to determine if there are associations between certain systemic medications and cataracts requiring surgical treatment. Comparing the 2,010 participants who underwent cataract surgery to the other participants in the study, they were significantly more likely to be older, less educated, white, non-Hispanic women with diabetes, hypertension, and dyslipidemia. After controlling for demographics, socioeconomic background, and certain comorbidities, the study demonstrated that tricyclic antidepressants (OR 2.21, p=0.001), insulin (OR 2.13, p<0.0001), and group III antiarrhythmics (OR 0.011, p<0.0001) were the three drug classes with the strongest positive association with cataract surgery while sex hormone therapy in women demonstrated the strongest negative association (OR 0.011, p<0.0001). Further studies can build upon these findings by conducting randomized clinical trials, classifying the type of cataract that required surgery, and evaluating medication compliance among participants.

Could ctDNA measurements play a role in clinically managing uveal melanoma?


Detection of circulating tumor DNA (ctDNA) in plasma has become a new tool for minimally invasive diagnosis and monitoring of treatment response and recurrence in some cancers. This single-center, retrospective study evaluated if ctDNA in plasma was measurable and provided clinically relevant data in 69 patients undergoing plaque brachytherapy or enucleation for uveal melanoma (UM). ctDNA was detectable in 20 patients during the perioperative period with a significant increase during the second and third day of brachytherapy, likely due to treatment-induced necrosis and apoptosis of cancer cells. Patients who developed detectable ctDNA levels during follow-up period of 21 months were significantly more likely to develop metastasis compared to patients with follow-up ctDNA that became undetectable. No association was found between detectability of ctDNA and tumor size, stage, or location. Limitations include a small sample size and exclusion of BAP1 in the multigene panel for detecting ctDNA. Results emphasized the potential for ctDNA as a biomarker for detecting metastasis before it is radiographically detectable and the recommendation to include genes not classically associated with UM in ctDNA gene panels.


In vivo confocal microscopy for diagnosis of Acanthamoeba keratitis


Corneal cultures could use a little help. Acanthamoeba is a protozoan found in water, air, and soil that can cause severe, painful, and sight threatening Acanthamoeba keratitis (AK). Corneal scraping cultures are the gold standard for diagnosis, which can be difficult. Acanthamoeba cysts and trophozoites may be identifiable by in vivo confocal microscopy (IVCM), and studies have shown high specificity and sensitivity of IVCM for the diagnosis of AK, comparable or superior to KOH prep or Gram stain. The purpose of this retrospective comparative case series was to determine the potential advantage of using IVCM for AK by comparing outcomes in patients diagnosed with the aid of IVCM versus by corneal culture only. They evaluated 26 eyes of 23 patients over a 5-year period. The diagnostic delay was significantly longer in the culture only group (25 ± 29 days) compared with the IVCM group (3 ± 3 days). At 6 months, there was a significant difference in best-corrected visual acuity between the culture-only group (1.46 ± 1.07) and the IVCM/C group (0.22 ± 0.22), after adjusting for baseline visual acuity. The results of this study suggest that IVCM may expedite the diagnosis of this rare disease, ultimately limiting vision loss. While future studies require larger samples and a more standardized protocol, IVCM could grow to be used as an adjunct tool in the diagnosis of AK.

Lens Landmarks

Ever wonder where those famous “EDTRS letters” come from? The Early Treatment Diabetic Retinopathy Study (ETDRS) explored the role of focal laser coagulation, panretinal photocoagulation (PRP), and aspirin use for the treatment of non-proliferative diabetic retinopathy (NPDR) and early proliferative diabetic retinopathy (PDR). A total of 3,711 patients were included in ETDRS and randomized into two cohorts according to aspirin use (aspirin, 650 mg/day, n = 1,856; placebo, n = 1855). For each patient, each eye was assigned to early or deferred photocoagulation. The cohort of early photocoagulation eyes was further subdivided according to timing of focal and panretinal/scatter photocoagulation. Photocoagulation in deferred eyes was initiated upon detection of high-risk PDR. 

Key Points:
  • Defined grading criteria for NPDR (see linked study with images)
  • Early focal photocoagulation reduced the risk of vision loss from diabetic macular edema (ETDRS Report Number 1, 9)
  • PRP decreased the risk of severe vision loss in patients with proliferative or severe non-proliferative diabetic retinopathy, but should be withheld in those with moderate or mild nonproliferative diabetic retinopathy due to adverse effects on visual field and acuity (ETDRS Report Number 9)
  • Aspirin did not alter the disease course of diabetic retinopathy. Furthermore, aspirin use was not associated with adverse ocular events, including vitreous or preretinal hemorrhage. (ETDRS Report Number 8, 19, 20)
Overall, the ETDRS demonstrated that early focal photocoagulation can avert vision loss related to diabetic macular edema. PRP is beneficial for patients with PDR or severe NPDR, but the risks outweigh the benefits for patients with mild or moderate NPDR. This study further laid the groundwork for many future Diabetic Retinopathy and other retina studies.

Question of the Week

A 45-year-old male presents to your office and complains of slowly progressive decreased vision in his left eye for 2 months. Visual acuity is 20/200. His fundus examination and OCT are shown below.
Which of the following best represents the pathophysiology of this patient’s condition?

A. Embolic phenomenon
B. Thrombosis at the level of the lamina cribrosa
C. Carotid stenosis
D. Compression of the central retinal vein due to an atherosclerotic arteriole

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Quiz Answer: B
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