Steve Lenier

home

authors

steve-lenier

This article was reviewed by Jeffrey Tapley, MD

In patients with endothelial dysfunction, performing Descemet membrane endothelial keratoplasty (DMEK) rapidly deturgesces an edematous cornea. In some cases that deturgescence reveals posterior corneal steepening similar to keratoconus, but the authors note recent studies have shown there is no genetic overlap between Fuchs’ dystrophy and keratoconus.

A retrospective review was performed to describe changes in corneal thickness, and identify the incidence of posterior corneal changes characteristic of keratoconus, following DMEK surgery.

The study was a retrospective chart review that included 50 eyes that received cataract surgery and 50 eyes that received DMEK for Fuchs’ Dystrophy. Scheimpflug images (done with an Oculus Pentacam) for each eye were reviewed. For the DMEK group, follow up Pentacam images from 6 months and 1 year were used. The central corneal thickness (CCT) of the preoperative cataract surgery eyes served as normal controls and was compared to the CCT of the postoperative DMEK eyes.

The 6 month and 1 year postoperative Pentacam images in the DMEK group were also reviewed for posterior elevation changes and localized steepening, characteristics that resemble keratoconus. Mean age, gender, preoperative CCT, and postoperative peripheral corneal thickness (PCT) were recorded. Statistical significance comparing CCT, PCT, and CCT:PCT was determined using the Student’s T-test.

Normal CCT from the 50 control eyes was 543 µm ± 35 µm. The 6-month postoperative CCT in the DMEK group was 534 µm±35 µm (P=0.23) and the 1-year CCT was 536 µm ± 35 µm (P=0.33).

19 out of 50 DMEK eyes (38%) had posterior steepening resembling keratoconus at the 6 month visit.

A subgroup analysis of the preoperative CCT from those 19 eyes vs 31 eyes without keratoconus-like changes was not statistically different (611 µm ± 51 µm vs 615 µm ± 56 µm, P = 0.80).

All 19 of those eyes had the same posterior corneal changes at the 1 year visit.

The authors concluded that CCT after DMEK was not statistically different compared to normal corneas at 6 months and 1 year postoperative. Localized posterior corneal steepening characteristic of keratoconus was seen in 38% of DMEK corneas at 6 months following surgery. The localized steepening persists out to 1 year postoperative, suggesting that there may be structural loss in the stroma. The steepening was not a function of preoperative CCT or postoperative PCT, and the authors believe it is likely a consequence of stromal keratocyte apoptosis due to chronic edema.

Limitations of the study include its retrospective nature and the small sample size, and it is noted that future studies should be performed focusing on identifying predictive factors for these corneal changes.

This article is based on Tapley’s presentation at the ARVO 2021 virtual annual meeting. Tapley has no financial disclosures.

Articles

A retrospective review was performed to describe changes in corneal thickness and to identify the incidence of posterior corneal changes characteristic of keratoconus, following DMEK surgery. Here’s what investigators found.

Considering keratoconus-like changes after DMEK in Fuchs' dystrophy

This article was reviewed by Deepak Shukla, PhD.

Optineurin, also known as optic neuropathy inducing protein, has involvement in a number of functions, according to Deepak Shukla, PhD. 

Optineurin is a glaucoma-associated gene, and mutations in this gene are also commonly reported in many other neurodegenerative diseases. Shukla presented a unique role for optineurin as a host defense factor, which he said had not been discussed before.

The goal of the authors’ study was to identify intrinsic host factors responsible for defending against viral infections of the eye. They used herpes simplex virus-1 (HSV-1) as a model virus to characterize optineurin. HSV keratitis (both epithelial and stromal) has the potential to cause vision loss, and as a result the virus is considered a leading cause of infection-related blindness. 

Shukla pointed out that about 80 percent of adults in the U.S. are infected with the virus, but only a small subset end up developing the disease, which demonstrates that immunity works. There is also plenty of evidence that all three forms of immunity—innate, adaptive, and cell autonomous intrinsic immunity—act in concert to prevent development of symptoms even though the virus lives in our system forever.

Shukla focused on a selective autophagy pathway that the authors believe acts to protect infection at the level of epithelium in some situations, and also at the level of neurons. They say optineurin is neuro-protective, especially against herpetic infections.

Optineurin is known to be involved in selective autophagy, signal transduction pathways, and necroptosis inhibition. It is a multi-domain, multi-functional protein, and for this study the LC3-binding domain, as well as ubiquitin-binding domain of this protein are important for the functions being described here.

The authors hypothesized that optineurin is an intrinsic defense factor against HSV-1 infection through selective degradation of viral proteins. They believe the presence of optineurin reduces viral load inside a cell. This happens via autophagy, which they believe is selective in nature.

In the current study, the researchers used optineurin knockout cells and wild-type cells that were positive for optineurin. They infected the cells with a green fluorescent protein (GFP) reporter virus.

The study showed that infection increases with time, which is natural. But in the optineurin-negative cells the infection went up significantly compared to the wild-type cells. The authors propose that the increase is not only at the level of individual cells but also at the level of virus spread from cell to cell.

Cell death was measured by flow cytometry and by counting infected cells or genomes. In all cases the authors found that presence of optineurin restricts infection, and its absence allows the virus to grow exponentially. 

Optineurin it already known to participate in the autophagy process, and in this case the authors feel it is selective autophagy, whereby optineurin selectively binds to some of the key viral proteins that are ubiquitinated by the target cells and diverts them to a lysozomal pathway where the degradation of these proteins occurs.

High-resolution microscopy shows that optineurin and HSV VP16 co-localize along with a marker for lysosomal-associated membrane protein 1, which is a marker for lysosomes. The fact that they all co-localize together suggests to the authors that this essential protein VP16 is degraded via autophagy during herpetic infection of cells.

Another indication that optineurin has an important effect in herpetic infection is that it seems to prevent encephalitis.

The authors found in animal studies that there wasn’t much effect on trigeminal ganglia, but in the brainstem there was exponential growth of virus in optineurin knockout animals, at both 4 days and 8 days post-infection. In the brain, the data at 4 days post-infection was not conclusive, but there was definitely a trend which became more conclusive and statistically significant by 8 days post-infection, that 10 fold increase in viral load was found in the brain.

So in the absence of optineurin the virus is able to grow faster, especially in the brainstem but also in the brain. The animals without optineurin also seemed to lose weight significantly, which is another indicator of the virus-related health effects on the host.

The most striking difference was at the level of survival. Optineurin-deficient animals tended to succumb to infection by 7 days post-infection. The authors believe this happens due to HSV-1 related damage to neurons in the brain, as they saw a lot of neurons dying in optineurin-deficient animals because of the herpetic infection.

The authors also noted that optineurin deficiency results in a lack of immune cells infiltrating into the brain. There was a much lower number of both CD4 and CD8 lymphocyte cells going to the central nervous system in optineurin-deficient animals.

In looking further at the death of neurons, the authors used in vitro cultured neurons from mouse brain, and found that in optineurin-deficient animals exposed to herpes, the neurons seemed to die much faster and in larger numbers than wild-type animals. So both neurons and animals died faster without optineurin.

They also found that a necroptosis inhibitor, necrostatin-1, is able to reverse the process, and both cell death, and death of the animals, can be reduced with its use. Weight gain also returned in the animals treated with the inhibitor.

Another interesting finding was that when infected with herpes, the animals, especially the knockout animals, lose their ability to recognize novel objects, by 30 days post infection. This also demonstrates damage to the neurons.

Knockout animals also had more instances of inflammation, and they tend to lose neurons in the cornea, eliminating corneal sensitivity.

Targets HSV-1 proteins, gB and VP16, for degradation by autophagy

Promotes lymph node activation and T-cell infiltration into the CNS

Prevents loss of corneal/whisker sensitivity


This article is based on Shukla’s presentation at the ARVO 2021 virtual annual meeting. Shukla has no disclosures.

Mutations in this glaucoma-associated gene may be commonly reported in many other neurodegenerative diseases.

Optineurin: Defending against viral infections of the eye

In a retrospective evaluation of 100 consecutive patients screened for refractive surgery candidacy, a team of investigators hoped to determine how adding corneal epithelial thickness maps to the process can affect patient screening.

A number of corneal imaging technologies are used to evaluate patients who ask about refractive surgery. It is now possible to add epithelial mapping to the screening process. 

Tips to chart a course for safe, effective refractive surgery

The authors routinely use a combination of Scheimpflug tomography and anterior segment optical coherence tomography (AS-OCT) in their practice, but until now had not analyzed what impact occurred with the addition of this epithelial mapping.


For each patient, screening was performed based on Scheimpflug tomography, clinical data, and patient history. 

Two masked reviewers made a decision on eligibility for corneal refractive surgery and choice of surgery.

The reviewers were then shown the patient’s epithelial thickness maps made from the AS-OCT, and the researchers determined the percentage of screenings that changed after evaluating the epithelial thickness maps, in candidacy for surgery, surgery of choice, and ranking of surgical procedures from most favorable to least favorable.


Following the evaluation of the epithelial thickness maps, candidacy for corneal refractive surgery changed in 17% of patients. 

Choroidal hypertransmission defects on en face OCT imaging predict geographic atrophy in patients

Of the patients whose candidacy changed, 58.82% resulted in screening in patients and 41.18% of the changes resulted in screening out patients.

In the subset of patients that remained eligible candidates for surgery, the surgery of choice changed in 20.83% of cases after evaluating the epithelial thickness maps. 

The ranking of surgical procedures, from most favorable to least favorable, changed in 36.11% of cases, with 13.89% of patients losing eligibility and 11.11% gaining eligibility, for at least 1 surgical procedure.

In the subset of patients in which eligibility for surgery, surgery of choice, and ranking of surgical procedures from most to least favorable did not change, the epithelial thickness maps increased the reviewers’ confidence in their decision in 49.12% of cases, decreased their confidence in 17.54% of cases, and had no impact on their level of confidence in 33.33% of cases.

Visualization with en face OCT offers value for ophthalmologists


The investigators found that epithelial thickness mapping derived from OCT imaging of the cornea alters candidacy for corneal refractive surgery, as well as choice of surgery, in a substantial percentage of patients. 

In addition, they found that epithelial thickness maps result in screening in a slightly larger percentage of patients who can be helped with corneal refractive surgery. Therefore, they deemed it a valuable tool for screening evaluations.

 
This article is based on Randleman’s presentation at the Association for Research in Vision and Ophthalmology 2021 Annual Meeting. Randleman has no relevant financial disclosures. This work was supported by Research to Prevent Blindness.

Investigators examine usefulness in refractive surgery evaluations.

Study targets utility of epithelial thickness mapping 


This article was reviewed by Sanjay Patel, MD

The authors performed this study in order to develop a severity scale for tomographic edema in Fuchs’ endothelial corneal dystrophy (FECD) based on Scheimpflug tomography maps, and to evaluate intra- and inter-observer variation for assessing severity.

They explained that Scheimpflug imaging can be used to detect tomographic patterns consistent with the presence of edema in FECD. 

These patterns are found in the posterior elevation and pachymetry maps, and are repeatable, and can be used to predict the prognosis of FECD. 

The authors of this study developed a severity scale for FECD based on these maps, and evaluated intra- and inter-observer variation for assessing severity.

This was a cross-sectional study in which eyes with a range of severity of FECD were examined by two cornea specialists and underwent Scheimpflug imaging with a Pentacam (Oculus).

Scheimpflug tomography pachymetry and posterior elevation maps were assessed for features of subclinical corneal edema, and an ordinal scale was developed to assess the severity of FECD based on the presence and extent of the tomographic features. 

The scale ranges from normal (grade 1) to severe (grade 6) edema, based on loss of parallel isopachs, displacement of the thinnest point of the cornea, and posterior surface depression within the central 4 mm of the cornea. 

Subtle findings suspicious for early tomographic edema were defined as grade 2. 

Progressive severity of edema was based on the depth of posterior surface depression (mild, moderate, advanced, and severe were grades 3-6, respectively).

Observers first standardized their grading with a training set of images. The severity of tomographic edema was then graded as 1-6 from

masked and randomized images, which were presented to both cornea specialists without associated clinical information.

Intra-observer (one observer evaluating the same images on two occasions separated by two weeks) and inter-observer agreement were assessed by using the kappa statistic (κ) with 95% confidence interval (CI), and McNemar’s test was used to assess for significant differences.



In this study, exact agreement between repeated assessments by one observer occurred for 97% (277/286) of eyes (κ=0.96, CI 0.93 to 0.99, p=0.88). All disagreements were by 1 grade only.

Exact agreement between assessments by both observers occurred for 85% (244/286) of eyes (κ=0.81, CI 0.76 to 0.86, p=0.12). 

Disagreements were by 1 grade for 40 eyes and by 2 grades for 2 eyes, and mainly occurred because one observer assigned increased severity relative to the other when determining normal tomography from those with suspicious findings of early edema.



The authors showed that assessing the severity of tomographic edema in FECD has excellent intra- and inter-observer agreement based on the proposed severity scale. 

They say the lower inter-observer agreement was more a result of lack of sufficient standardization between observers rather than limitations of the imaging technology, especially for findings suspicious of early edema.

They point out further investigation is needed to determine if this severity assessment can detect tomographic progression and how it relates to clinical findings


This article is based on Patel’s presentation at the ARVO 2021 virtual annual meeting. Patel is a consultant to GlaxoSmithKline, Senju Pharmaceuticals, Santen Inc., and Emmecell. None are relevant to this topic.

Investigators sought to develop a severity scale for tomographic edema in FECD based on Scheimpflug tomography maps, and to evaluate intra- and inter-observer variation for assessing severity.

Assessing the severity of Fuchs’ endothelial corneal dystrophy by using Scheimpflug tomography


This article was reviewed by Brandon Baksh, BA, and Anat Galor, MD, MSPH

Chronic pain is a common and often debilitating condition. Chronic pain syndromes can be localized to the head and face, and involve the trigeminal system, for example in migraine and trigeminal neuralgia, explained Brandon Baksh, BA.

He continued, saying chronic pain syndromes can also be widespread, such as in fibromyalgia, or localized to areas outside the head and face, such as back pain, and that nerve abnormalities have been linked to chronic pain syndromes.

“As eyecare providers,” he said, “we can assess this link between nerve abnormalities and chronic pain.” 

He pointed out that corneal sensitivity can be measured in the office.


Corneal sensitivity is altered in several eye conditions. However, its relationship with chronic pain conditions outside of the eye is not clear.

To learn more about how chronic pain conditions outside of the eye impact corneal sensitivity, the authors investigated whether individuals with chronic trigeminal pain conditions have differences in corneal sensitivity compared with individuals with chronic pain conditions not localized to the trigeminal system.

Their hypothesis was that patients with chronic trigeminal pain have differences in corneal mechanical detection threshold compared to those who have chronic pain conditions that are not localized to the trigeminal system.

A cross sectional study was performed of South Florida veterans with chronic pain conditions (>3 months duration) seen at an eye clinic. 

The main independent variables were pain diagnoses and locations, as recorded by the participants through a survey. 

The main dependent variable was corneal mechanical detection threshold, which was assessed using a modified Belmonte aesthesiometer.

To assess confounding variables, data was collected on demographics, dry eye symptoms and signs, mental health indices, systemic co-morbidities, and quality of life indices.

Individuals were split into two groups based on their pain diagnosis:

chronic pain conditions that involved the trigeminal system

chronic pain conditions that did not localize to the trigeminal system


Corneal mechanical threshold was assessed with a modified Belmonte aesthesiometer:

Pulses of air at room temperature were used, on the right eye.

Started at 10mL/min, and waited 15 seconds between pulses

Increased by 10mL/min, until the patient could feel the pulse

This was repeated a 2nd time and the mean was used

If the difference between the 2 trials was > 20, a 3rd reading was done

Baksh noted that a lower detection threshold using the Belmonte aesthesiometer meant a higher corneal sensitivity.

Continuous variables were assessed via the independent t-test. Correlations were assessed via Pearson r coefficient, and categorical variables were assessed via Chi-square test. 

All reported p-values are two-tailed and p<0.05 was considered statistically significant.



This study included 568 individuals with one or more chronic pain conditions. The mean age was 61 +/- 10.5 years. 89% were male, 44% self-identified as White, and 25% self-identified as Hispanic. 

The mean corneal mechanical detection threshold was 81 +/- 38 mL/min, with a range of 10-240 mL/min.

The authors found that the Trigeminal pain group (n=122) had a lower mean corneal mechanical detection threshold (i.e. higher sensitivity) (73+/-31) compared to the Other pain group (n=446, mean threshold 84+/-40). This was statistically significant.

The authors also assessed continuous variables. Variables that came out significantly correlated with lower corneal mechanical detection threshold (higher sensitivity) included a high depression score, a high PTSD score, worse dry eye symptoms, worse eye pain, as well as worse quality of life, lower age, lower cholesterol and lower triglycerides.

Lower corneal mechanical detection threshold (higher sensitivity) may be associated with pain phenotypes such as the presence of chronic pain involving the trigeminal system, 5 or more pain conditions, and the presence of arthritis.

Beyond pain phenotypes, additional factors that may play a role include a higher depression score, Black race, dyslipidemia, and CPAP use.


This article is based on Baksh’s presentation at the ARVO 2021 virtual annual meeting. Baksh has no financial disclosures.

A cross sectional study investigated how chronic pain conditions outside of the eye impact corneal sensitivity. 

Corneal mechanical sensitivity in individuals with chronic pain

In traditional machine learning, a programmer tells the machine the features of whatever it is supposed to identify. In deep learning, the features are picked out by the neural network, without human intervention. 

Instead, the program is given a large sample of appropriately labeled images, and the program is able to learn to recognize patterns by itself, without pre-existing rules set by the programmer. 

In recent years, convolutional neural networks (CNNs) have been developed that provide higher accuracy in image detection tasks using multiple layers to progressively extract higher level features. 

These CNNs can be used to automatically grade retina images of patients with diabetic retinopathy, and also have been used in glaucoma, but there is a “paucity of research” in the field of cornea.

Keratoconus is a progressive disease that leads to the thinning of the cornea. If caught early, disease progression can be halted, using corneal collagen crosslinking.

Despite treatment, approximately 10% of patients continue to progress, eventually requiring corneal transplantation.

The goal of this study was to implement and test a trained deep learning algorithm using pre-operative corneal topography scans in order to 1) classify between keratoconus and normal corneas, 2) stage the disease according to Amsler-Krumeich scale, and 3) predict whether a patient will be likely to benefit from crosslinking treatment.

Oculus Pentacam images were processed and standardized for comparison. The algorithm used is an 11-layer convolutional neural network programmed using TensorFlow software with the assistance of a data scientist (

Visualized model of the algorithm being used for image comparison.

A method called cross-validation was used to test the method. The data is split into two parts, a training set and a validation set. 

The training set uses 80% of the image set to train the model, and the validation set uses 20% of the images to evaluate the model’s performance, including images the network has not seen before.

Final accuracies were reported after 50 epochs (one cycle through the full training dataset) for all three stages of the study.

In total, 2450 scans were included (1215 keratoconus and 1235 controls) for stage 1, 985 keratoconus scans were classified according to the Amsler-Krumeich scale for stage 2, and 138 keratoconus scans (69 progressed and 69 stabilized) were labeled for stage 3.

In stage 1, differentiating eyes with keratoconus from normal eyes, a very high validation accuracy rate (99.3%) was achieved. For stage 2, grading keratoconus, the validation accuracy was 73.5%. 

One reason to account for the lower accuracy is the fact that the grading system used does not incorporate manifest refraction data. Implementing a marker system, the authors were able to improve the accuracy 14%, to 87.8%. 

Because there were more images used in stage 1 than in stage 2, the authors re-did the testing of stage 1 with fewer images, and achieved a validation accuracy of 83.6%, which is closer to that found in stage 2.

For stage 3, assessing the accuracy of the CNN in predicting whether a patient with keratoconus will stabilize following crosslinking, or continue to progress, the images were split into groups of stabilized vs progressed. 

The program was unable to learn any useful parameters that would improve its accuracy in categorizing the scans, and only achieved a validation accuracy of 53.6%.

The sample size may have limited this study.Another limitation is that with deep learning algorithms it’s not possible to visualize what parameters the algorithm is using for classification. 

However researchers have now developed class activation maps to highlight regions to better elucidate the inner workings of the deep learning black box. 

Last, the authors noted the results of this detection is limited to Pentacams, and without more images it can’t be generalized to other topographers such as the OrbScan.


The authors were able to build and test a deep learning model that was able to diagnose keratoconus with an accuracy of 99.3%, and stage the disease at 87.8%. 

They said that even though it was not able to predict disease progression, the applications of convolutional neural networks are encouraging and can be utilized to solve practical clinical problems and serve as an adjunct tool in clinical decision making in the near future.


This article is based on Dr. Liu‘s presentation at the ARVO 2021 virtual annual meeting. Dr. Liu has no financial disclosures.

A study sought to implement and test a trained deep learning algorithm using pre-operative corneal topography scans in order to classify between keratoconus and normal corneas, stage the disease, and predict whether a patient will be likely to benefit from CXL treatment.