Predictors of Receiving Keratoplasty for Keratoconus

Dramatic Reduction in Corneal Transplants for Keratoconus 15 Years After the Introduction of Corneal Collagen Crosslinking

PURPOSE

The aim of this study was to investigate the effect of the implementation of corneal collagen crosslinking (CXL) on the frequency of corneal transplants among patients with keratoconus (KC) in the same region.

METHODS

Before the introduction of CXL in 2007, 55 primary corneal transplants had been conducted in patients with KC (2005 and 2006) at the Department of Ophthalmology, Oslo University Hospital, Norway. We collected data from our corneal transplant registry for 2021 and 2022. The primary outcome was the number of corneal transplants performed in patients with KC. Age, sex, visual acuity (logarithm of the minimal angle of resolution), KC stage according to the Amsler-Krumeich classification system, and steepest keratometry reading (maximum keratometry, Pentacam, HR) were recorded. Furthermore, we registered the annual number of CXL treatments conducted from 2007 to 2022.

RESULTS

A total of 352 corneal transplants were performed in 2021 and 2022. Among them, 11 (3.1%) were transplants for patients with KC. All included patients were male; further, 90.1% and 9.1% of the patients were graded stages 4 and 3, respectively. The mean maximum keratometry was 79.0 diopter (range 61.0-109). The mean best-corrected visual acuity (logarithm of the minimal angle of resolution) was 1.3 (range 0.2-3.0). In 2021 to 2022, 431 CXL treatments were performed.

CONCLUSIONS

There was a significant decrease in the number of corneal transplants performed in patients with KC 15 years after the introduction of CXL. This indicates that the availability of CXL treatment over many years may considerably reduce the need for keratoplasties in this group of patients.

Factors Associated With Receipt of Crosslinking for Keratoconus

PURPOSE

The aim of this study was to identify factors associated with receipt of standard fluence epithelium-off crosslinking (CXL) for keratoconus (KCN).

METHODS

This retrospective, cross-sectional study reviewed electronic health records of treatment-naive patients with KCN seen at the Wilmer Eye Institute between January 2017 and September 2020. Tomographic data were derived from Pentacam (Oculus, Wetzlar, Germany) devices. Multivariable population-average model using generalized estimating equations adjusting for age, sex, race, national area deprivation index, vision correction method, and disease severity was used to identify factors associated with receipt of CXL.

RESULTS

From 583 patients with KCN, 97 (16.6%) underwent CXL for KCN. Patients who received CXL in at least 1 eye were significantly younger (mean 24.0 ± 7.8 years) than patients who had never undergone CXL (33.4 ± 9.3 years) ( P < 0.001). In multivariable analysis, Black patients had 63% lower odds of receiving CXL for KCN (OR: 0.37, 95% CI, 0.18-0.79) versus White patients, and older age was protective against receipt of CXL (OR: 0.89 per 1-year increase, 95% CI, 0.86-0.93). Comparison of characteristics by race demonstrated that Black patients presented with significantly worse vision, higher keratometric indices (K1, K2, and Kmax), and thinner corneal pachymetry at baseline versus White or Asian patients.

CONCLUSIONS

In this clinical cohort of patients with KCN from a tertiary referral center, Black patients were less likely to receive CXL presumably because of more advanced disease at presentation. Earlier active population screening may be indicated to identify and treat these patients before they become ineligible for treatment and develop irreversible vision loss. Such strategies may improve health equity in KCN management.

Keratoplasty in the United States: Trends and Indications From 2015 to 2020

PURPOSE

The aim of this study was to report trends in keratoplasty techniques and indications in the United States from 2015 to 2020.

METHODS

This retrospective review of annual reports from the Eye Bank Association of America assessed domestic corneal graft distribution and surgical indication data for various types of keratoplasty. Trends in procedure volume and indications from 2015 to 2020 were analyzed using the Cochran-Armitage test.

RESULTS

The total number of corneal transplants increased from 47,903 in 2015 to 49,143 in 2019, with a decline to 42,257 in 2020, most likely due to COVID-19. Penetrating keratoplasty (PK) volume decreased from 2015 to 2020 (19,160-15,402, 40% to 36.4%, P < 0.001), continuing a trend from the previous decade. Descemet membrane endothelial keratoplasty as a percentage of all keratoplasty procedures increased (9.8%-27.8%, P < 0.001), whereas Descemet stripping automated endothelial keratoplasty (47%-33.9%, P < 0.001) and anterior lamellar keratoplasty (ALK) decreased (2.3%-1.2%, P < 0.001).From 2017 to 2020, repeat corneal transplant was the most common specific indication for PK while ectasias/thinnings decreased in prevalence (15.6%-11.5%, P < 0.001). Ectasias/thinnings and endothelial dystrophy remained the leading indications for ALK and endothelial keratoplasty, respectively.

CONCLUSIONS

From 2015 to 2020, keratoplasty trends in the United States showed a continuation of the decrease in PK and increase in Descemet membrane endothelial keratoplasty observed in the previous decade. The most common domestic indications from 2017 to 2020 have been repeat corneal graft, endothelial dystrophy, and ectasias/thinnings for PK, EK, and ALK, respectively.

Vitamin D Supplementation Impacts Systemic Biomarkers of Collagen Degradation and Copper Metabolism in Patients With Keratoconus

Purpose

To evaluate the impact of vitamin D (Vit D) supplementation on systemic biomarkers of collagen degradation, inflammation, oxidative stress, and copper metabolism in adolescent patients with keratoconus (KC).

Methods

This was a prospective observational pilot study. Twenty patients (age range, 16-19 years) presenting KC and Vit D insufficiency (<30 ng/mL) were included. Vit D supplementation was prescribed by their general practitioner as per the standard of care. Patients were followed up for 12 months. At each visit, best spectacle-corrected visual acuity (BSCVA), maximal keratometry (Kmax), and thinnest corneal thickness (TCT) were evaluated. The primary outcome of the study was the proportion of patients with Kmax progression of less than 1 D throughout the 12-month follow-up time. Blood samples were collected at different time points to evaluate Vit D levels and systemic markers of collagen degradation, inflammation, oxidative stress, and copper metabolism by ELISA or RT-PCR.

Results

Lower Vit D levels in the plasma were correlated with higher levels of systemic biomarkers of collagen degradation. Vit D supplementation increased the cell availability of copper. Moreover, stabilization of KC progression was found in 60% of patients (72% of eyes) after 12 months with Vit D supplementation. BSCVA, Kmax, and TCT rates remained stable during the observation period.

Conclusions

Our findings support that Vit D administration could affect ocular and systemic biomarkers in KC and illuminate a possible mechanism that can be used to develop new treatment alternatives.

Translational Relevance

Although KC therapy currently relies exclusively on surgical procedures, Vit D supplementation may offer a non-invasive and inexpensive alternative with minimal associated side effects.

The Frequency of Visual Field Testing in a US Nationwide Cohort of Individuals with Open-Angle Glaucoma

PURPOSE

Visual field testing that is not frequent enough results in delayed identification of open-angle glaucoma (OAG) progression. Guidelines recommend at least annual testing. It is not known how frequently patients with OAG across the United States receive visual field testing and how patient characteristics and circumstances influence this frequency. If US patients with OAG do not receive visual field tests frequently enough, interventions to increase this frequency or to develop other forms of testing visual function may reduce unidentified OAG vision loss.

DESIGN

Retrospective cohort study.

PARTICIPANTS

The TruvenHealth MarketScan Commercial Claims Database (IBM) contains demographic and claims data for > 160 million individuals across the United States from 2008 to 2017. We identified enrollees in the database with a recorded diagnosis of OAG (International Classification of Diseases, Ninth Revision, Clinical Modification and International Classification of Diseases, Tenth Revision, Clinical Modification codes 356.1x and H40.1x, respectively). We excluded those aged < 40 years at the time of their first OAG diagnosis, those without at least 1 confirmatory OAG diagnosis at a subsequent visit, and those with < 4 years of follow-up data after OAG diagnosis.

METHODS

We calculated the number of visual field tests that each enrollee with OAG underwent per year and categorized the enrollees based on that number (0, > 0 to < 0.9, ≥ 0.9 to ≤ 1.1, > 1.1 to ≤ 2.1, and > 2.1). We used negative binomial regression to investigate the demographic or health variables that were associated with the frequency of visual field tests that enrollees with OAG received.

MAIN OUTCOME MEASURES

Frequency of visual field testing among enrollees with OAG.

RESULTS

Of the 380 029 enrollees included in the study, 33 267 (8.8%) did not receive a visual field test during the study period, 259 349 (68.2%) underwent > 0 to < 0.9 visual field tests per year, 42 129 (11.1%) underwent ≥ 0.9 to ≤ 1.1 visual field tests per year, 42 301 (11.1%) underwent > 1.1 to ≤ 2.1 visual field tests per year, and 2983 (0.8%) underwent ≥ 2.1 visual field tests per year. The median number of visual field tests per year was 0.63 (interquartile range, 0.33-0.88; mean, 0.65).

CONCLUSIONS

More than 75% of enrollees with OAG received < 1 visual field test per year and, thus, did not receive guideline-adherent glaucoma monitoring.

Independent and interactive effects of eye rubbing and atopy on keratoconus

Purpose

To evaluate the independent and interactive effects of eye rubbing and atopy on keratoconus (KC) in central China.

Methods

A total of 330 KC patients and 330 controls were recruited in the case-control study. Eye rubbing and history of atopy were recorded through face-to-face interviews. The association between KC and eye rubbing, atopy, interactive effects of eye rubbing and atopy were analyzed by logistic regression, and the odds ratios (OR), relative excess risk due to interaction (RERI), attributable proportion (AP), synergy (S) index, and 95% confidence intervals (95% CI) were calculated.

Results

A total of 228 patients (69.09%) had an eye rubbing history, and 53 (16.06%) had an atopy history in the KC group, which were both higher than that in the control group (p<0.001). Eye rubbing and atopy were positively associated with KC in multivariate analysis, with ORs (95% CIs) of 15.11 (10.02, 22.80) and 5.30 (2.59, 10.84), respectively. Compared to non-eye rubbing and non-atopy eyes, the risk for eye rubbing coexisted with atopy was 52.31 (12.25, 223.35). No significant associations were found between KC and multiplicative interaction (p=0.608). The RERI, AP, and S values were 32.89 (-43.35, 109.14), 0.63 (0.05, 1.21), and 2.79 (0.56, 13.96), respectively, with no significant association between additive interaction and KC. No significant associations were found between eye rubbing, atopy and the severity of KC (p>0.05).

Conclusion

Eye rubbing and atopy were separately positively associated with KC, and there was a strong impact of coexistent eye rubbing and atopy on KC in China. Further multi-center and cohort study need to be conducted to explore the role of eye rubbing and atopy in the occurrence and development of KC.

Indications for keratoplasty in management of corneal ectasia

PURPOSE OF REVIEW

The current review aims to describe recent advancements in treatment of corneal ectasias and its effect on indications for corneal transplantation.

RECENT FINDINGS

The majority of patients affected by ectatic corneal disease use contact lenses to correct resulting astigmatism. Patients who are intolerant of contact lenses or cannot achieve acceptable vision through conservative measures could consider keratoplasty. However, continuing advancements in both nonsurgical and surgical treatments are either reducing or delaying the need for keratoplasty in patients affected by ectatic corneal disease.

SUMMARY

Corneal transplantation has been the mainstay of treatment for patients with advanced ectatic corneal disease. In the past decade, numerous improvements have been occurred to make contact lenses not only more effective for visual correction, but also more comfortable. Although corneal cross-linking is the only proven treatment known to prevent progression of disease, several other therapies show early potential for those in which cross-linking is contraindicated. Patients now have access to a wider range of therapies before considering keratoplasty.

Deep Anterior Lamellar Keratoplasty and Penetrating Keratoplasty for Keratoconus: A Claims-Based Analysis

PURPOSE

The purpose of this study was to report 1) demographic and clinical characteristics for US patients with keratoconus undergoing deep anterior lamellar keratoplasty (DALK) or penetrating keratoplasty (PK) and 2) complication rates for the 2 procedures.

METHODS

We performed a retrospective review of 2010 to 2018 health records for patients with keratoconus age younger than 65 years using the IBM MarketScan Database. A multivariable model adjusting for potential confounders was used to determine factors associated with receiving DALK over PK. Rates of complications 90 days and 1 year postoperatively were calculated. For select complications only (repeat keratoplasty, glaucoma surgery, and cataract surgery), Kaplan-Meier survival curves were additionally constructed over a period of up to 7 years.

RESULTS

A total of 1114 patients with keratoconus (mean age: 40.5 ± 12.6 years) were included in the analysis. Hundred nineteen received DALK, and 995 received PK. Regional differences exist, with patients in the north central United States having greater odds of receiving DALK than northeastern patients (OR = 5.08, 95% confidence interval, 2.37-10.90). Rates of endophthalmitis, choroidal hemorrhage, infectious keratitis, graft failure, graft rejection, postoperative cataract, glaucoma, or retinal surgery were all low at 90 days and 1 year. Complication rates for DALK and PK were both low beyond 1 year for repeat keratoplasty, cataract, and glaucoma surgery.

CONCLUSIONS

There are regional differences between DALK and PK utilization rates. In addition, DALK and PK complication rates in this nationally representative sample are low at 1 year and beyond, but further studies are needed to assess whether longer-term complications differ by procedure type.