Outcomes and Complications of Limbal Stem Cell Allograft Transplantation: A Report by the American Academy of Ophthalmology

PURPOSE

To review the published literature on the safety and outcomes of keratolimbal allograft (KLAL) transplantation and living-related conjunctival limbal allograft (lr-CLAL) transplantation for bilateral severe/total limbal stem cell deficiency (LSCD).

METHODS

Literature searches were last conducted in the PubMed database in February 2023 and were limited to the English language. They yielded 523 citations; 76 were reviewed in full text, and 21 met the inclusion criteria. Two studies were rated level II, and the remaining 19 studies were rated level III. There were no level I studies.

RESULTS

After KLAL surgery, best-corrected visual acuity (BCVA) improved in 42% to 92% of eyes at final follow-up (range, 12-95 months). The BCVA was unchanged in 17% to 39% of eyes and decreased in 8% to 29% of eyes. Two of 14 studies that evaluated the results of KLAL reported a notable decline in visual acuity over time postoperatively. Survival of KLAL was variable, ranging from 21% to 90% at last follow-up (range, 12-95 months) and decreased over time. For patients undergoing lr-CLAL surgery, BCVA improved in 31% to 100% of eyes at final follow-up (range, 16-49 months). Of the 9 studies evaluating lr-CLAL, 4 reported BCVA unchanged in 30% to 39% of patients, and 3 reported a decline in BCVA in 8% to 10% of patients. The survival rate of lr-CLAL ranged from 50% to 100% at final follow-up (range, 16-49 months). The most common complications were postoperative elevation of intraocular pressure, persistent epithelial defects, and acute allograft immune rejections.

CONCLUSIONS

Given limited options for patients with bilateral LSCD, both KLAL and lr-CLAL are viable choices that may provide improvement of vision and ocular surface findings. The studies trend toward a lower rejection rate and graft failure with lr-CLAL. However, the level and duration of immunosuppression vary widely between the studies and may impact allograft rejections and long-term graft survival. Complications related to immunosuppression are minimal. Repeat surgery may be needed to maintain a viable ocular surface. Reasonable long-term success can be achieved with both KLAL and lr-CLAL with appropriate systemic immunosuppression.

FINANCIAL DISCLOSURE(S)

Proprietary or commercial disclosure may be found after the references.

Cornea Classic: Stern, Beuerman, Fox, Gao, Mircheff, and Pflugfelder, "The Pathology of Dry Eye: The Interaction Between the Ocular Surface and Lacrimal Glands" (1998)

ABSTRACT

In one of the most frequently cited articles from Cornea , Stern et al's "The pathology of dry eye: the interaction between the ocular surface and lacrimal glands" (1998) revolutionized our current understanding of the pathophysiology of dry eye disease.

Advanced Corneal Imaging in Keratoconus: A Report by the American Academy of Ophthalmology

PURPOSE

To review the published literature on the diagnostic capabilities of the newest generation of corneal imaging devices for the identification of keratoconus.

METHODS

Corneal imaging devices studied included tomographic platforms (Scheimpflug photography, OCT) and functional biomechanical devices (imaging an air impulse on the cornea). A literature search in the PubMed database for English language studies was last conducted in February 2023. The search yielded 469 citations, which were reviewed in abstract form. Of these, 147 were relevant to the assessment objectives and underwent full-text review. Forty-five articles met the criteria for inclusion and were assigned a level of evidence rating by the panel methodologist. Twenty-six articles were rated level II, and 19 articles were rated level III. There were no level I evidence studies of corneal imaging for the diagnosis of keratoconus found in the literature. To provide a common cross-study outcome measure, diagnostic sensitivity, specificity, and area under the receiver operating characteristic curve (AUC) were extracted. (A perfect diagnostic test that identifies all cases properly has an AUC of 1.0.) RESULTS: For the detection of keratoconus, sensitivities for all devices and parameters (e.g., anterior or posterior corneal curvature, corneal thickness) ranged from 65% to 100%. The majority of studies and parameters had sensitivities greater than 90%. The AUCs ranged from 0.82 to 1.00, with the majority greater than 0.90. Combined indices that integrated multiple parameters had an AUC in the mid-0.90 range. Keratoconus suspect detection performance was lower with AUCs ranging from 0.66 to 0.99, but most devices and parameters had sensitivities less than 90%.

CONCLUSIONS

Modern corneal imaging devices provide improved characterization of the cornea and are accurate in detecting keratoconus with high AUCs ranging from 0.82 to 1.00. The detection of keratoconus suspects is less accurate with AUCs ranging from 0.66 to 0.99. Parameters based on single anatomic locations had a wide range of AUCs. Studies with combined indices using more data and parameters consistently reported high AUCs.

FINANCIAL DISCLOSURE(S)

Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.

Update on pharmacotherapy for dry eye

PURPOSE OF REVIEW

This review provides an overview of pharmacologic treatments for dry eye disease (DED), with a focus on newer developments.

RECENT FINDINGS

Along with the existing treatments, there are several new pharmacologic treatments available and being developed for DED.

SUMMARY

There are many currently available options for treatment of DED, and ongoing research and development to expand potential treatments for patients with DED.

Dry Eye Subtypes in the Dry Eye Assessment and Management (DREAM) Study: A Latent Profile Analysis

Purpose

Dry eye disease (DED) is a heterogeneous condition with poorly characterized subtypes. The DREAM study was a large multicenter randomized clinical trial that did not find omega-3 to be more effective than placebo in treating symptomatic DED. We performed secondary analysis of DREAM data to characterize DED subtypes and their omega-3 response.

Methods

A total of 535 patients with moderate-to-severe DED were randomized to omega-3 or placebo treatment for one year. We used latent profile analysis to identify subtypes based on baseline Ocular Surface Disease Index, tear break-up time (TBUT), anesthetized Schirmer's test, corneal and conjunctival staining, and meibomian gland dysfunction (MGD). We evaluated omega-3's effect for each subtype using generalized linear regression.

Results

Five clinically meaningful DED subtypes were identified. They differed significantly in sex (P < 0.001) and race (P = 0.02). Subtype 1 had the most severe DED signs yet milder symptoms and was associated with more Sjögren's syndrome (21%, P < 0.001). Subtype 2 had the mildest DED signs except MGD. Subtype 3 had the most severe symptoms, out of proportion to DED signs. Subtype 4 had relatively milder symptoms and MGD. Subtype 5 had severe MGD and TBUT and was associated with rosacea (29%, P = 0.04). Omega-3 was not significantly more beneficial than placebo for any subtype.

Conclusions

Five clinically meaningful DED subtypes differed significantly in demographics, symptoms, signs, and systemic disease associations. Omega-3 was not significantly more effective than placebo for any subtype.

Translational Relevance

T3 translational research identifying subtypes in the DREAM study can improve DED clinical classification and targeted management.

Feasibility of a Risk-Based Approach to Cataract Surgery Preoperative Medical Evaluation

Importance

In 2019, the US Centers for Medicare & Medicaid Services implemented the Patients Over Paperwork initiative, allowing hospitals and ambulatory surgery centers to establish their own policies on preoperative history and physical requirements. A risk-based approach to preoperative medical evaluation may allow surgeons to provide high-value patient care.

Objective

To assess the feasibility of a risk-based approach to cataract surgery preoperative medical evaluation through a lens of safety and throughput.

Design, Setting, and Participants

A pilot study was performed to evaluate the implementation of a risk-based approach to preoperative medical evaluation for cataract surgery using a virtual medical history questionnaire. The intervention group, seen from June to September 2020, received the risk assessment and those who were low risk proceeded to surgery without further preoperative evaluation prior to the day of surgery. The preintervention control group included patients who received standard care from January to December 2019.

Main Outcomes and Measures

Primary outcomes included rates of intraoperative complications, noneye-related emergency department visits within 7 days, inpatient admissions within 7 days of surgery, case delays, and rates of case cancellation. The secondary outcome included patient perception regarding preoperative care.

Results

A total of 1095 patients undergoing cataract surgery were included in the intervention group (1813 [58.2%] female) and 3114 were in the control group (621/1095 [56.7%] female). The mean (SD) age was 68.6 (11.0) in the control group and 68.4 (10.5) in the intervention group. The intervention group included 126 low-risk individuals (11.5%) and 969 individuals who received standard care (88.5%). There were no differences between the control and intervention groups in terms of rates of intraoperative complications (control group vs intervention group: 21 [0.7%] vs 3 [0.3%]; difference, -0.4% [95% CI, -0.82 to 0.02]), 7-day noneye-related ED visits (5 [0.2%] vs 3 [0.3%]; difference, 0.1% [95% CI, -0.23 to 0.45]), 7-day inpatient admissions (6 [0.2%] vs 2 [0.2%]; difference, -0.01% [95% CI, -0.31 to 0.29]), or same-day cancellations (31 [0.8%] vs 10 [0.6%]; difference, -0.15% [95% CI, -0.63 to 0.34]). The control group had more case delays (59 [1.9%] vs 7 [0.6%]; difference, -1.3% [95% CI, -1.93 to -0.58]).

Conclusions and Relevance

This study suggests that a virtual, risk-based approach to preoperative medical evaluations for cataract surgery is associated with safe and efficient outcomes. These findings may encourage health care systems and ambulatory surgery centers to tailor preoperative requirements for low-risk surgery patients.

Corneal Confocal Microscopy Predicts the Development of Diabetic Neuropathy: A Longitudinal Diagnostic Multinational Consortium Study

OBJECTIVE

Corneal nerve fiber length (CNFL) has been shown in research studies to identify diabetic peripheral neuropathy (DPN). In this longitudinal diagnostic study, we assessed the ability of CNFL to predict the development of DPN.

RESEARCH DESIGN AND METHODS

From a multinational cohort of 998 participants with type 1 and type 2 diabetes, we studied the subset of 261 participants who were free of DPN at baseline and completed at least 4 years of follow-up for incident DPN. The predictive validity of CNFL for the development of DPN was determined using time-dependent receiver operating characteristic (ROC) curves.

RESULTS

A total of 203 participants had type 1 and 58 had type 2 diabetes. Mean follow-up time was 5.8 years (interquartile range 4.2-7.0). New-onset DPN occurred in 60 participants (23%; 4.29 events per 100 person-years). Participants who developed DPN were older and had a higher prevalence of type 2 diabetes, higher BMI, and longer duration of diabetes. The baseline electrophysiology and corneal confocal microscopy parameters were in the normal range but were all significantly lower in participants who developed DPN. The time-dependent area under the ROC curve for CNFL ranged between 0.61 and 0.69 for years 1-5 and was 0.80 at year 6. The optimal diagnostic threshold for a baseline CNFL of 14.1 mm/mm² was associated with 67% sensitivity, 71% specificity, and a hazard ratio of 2.95 (95% CI 1.70-5.11; P < 0.001) for new-onset DPN.

CONCLUSIONS

CNFL showed good predictive validity for identifying patients at higher risk of developing DPN ∼6 years in the future.

Ocular Discomfort and Quality of Life Among Patients in the Dry Eye Assessment and Management Study

PURPOSE

To assess the association of severity of ocular discomfort with measures of quality of life among patients with moderate to severe dry eye disease (DED).

METHODS

This is a prospective, observational, cohort study within a randomized clinical trial. Patients (N = 535) in the Dry Eye Assessment and Management study with moderate to severe DED completed the Ocular Surface Disease Index on DED symptoms, the SF-36 on quality of life, and the Brief Ocular Discomfort Inventory questionnaire and had a comprehensive ophthalmic assessment by a study-certified clinician. The ocular discomfort on average over the past week was scored on an 11-point scale (0 for no discomfort and 10 for discomfort as bad as you can imagine).

RESULTS

The average ocular discomfort scores for patients ranged from 0 to 10, with a mean of 4.28. Discomfort scores did not vary with demographic characteristics, signs of DED, self-reported depression, or self-reported nonocular pain conditions. Ocular discomfort scores did correlate moderately to strongly with total Ocular Surface Disease Index scores (Spearman correlation coefficient, rs, 0.47-0.67) and with measures of interference with activities of daily living [general activity level, mood, walking ability, ability for normal work, relations with other people, sleep, and enjoyment of life (rs = 0.39-0.65)].

CONCLUSIONS

Among patients in the Dry Eye Assessment and Management study, worse ocular discomfort was associated with worse overall DED symptoms and interfered to a greater degree with activities of daily living. Ocular discomfort is an important part of the assessment of patients with DED.

The Dry Eye Assessment and Management (DREAM) extension study - A randomized clinical trial of withdrawal of supplementation with omega-3 fatty acid in patients with dry eye disease

PURPOSE

To determine effects of continued or discontinued use of omega-3 (ω3) fatty acid supplements through a randomized withdrawal trial among patients assigned to ω3 supplements in the first year of the DREAM study.

METHODS

Patients who were initially assigned to ω3 (3000 mg) for 12 months in the primary trial were randomized 1:1 to ω3 active supplements or placebos (refined olive oil) for 12 more months. The primary outcome was change in the Ocular Surface Disease Index (OSDI) score. Secondary outcomes included change in conjunctival staining, corneal staining, tear break-up time, Schirmer test, and adverse events.

RESULTS

Among 22 patients assigned to ω3 and 21 to placebo supplements, the mean change in OSDI score between month 12 and 24 was similar between treatment groups (mean difference in change -0.6 points, 95% confidence interval [CI], (-10.7, 9.5), p = 0.91). There were no significant differences between groups in mean change in conjunctival staining (difference in mean change -0.5 points; 95% CI (-1.2, 0.3)), corneal staining (-0.3 points; 95% CI (-1.2, 0.3)), tear break-up time (-0.8 s; 95% CI (-2.6, 0.9)) and Schirmer test (0.6 mm, 95% CI (-2.0, 3.2)). Rates of adverse events were similar in both groups.

CONCLUSION

Among patients who received ω3 supplements for 12 months in the primary trial, those discontinuing use of ω3 for an additional 12 months did not have significantly worse outcomes compared to those who continued use of ω3. ClinicalTrials.gov number NCT02128763.

Corneal confocal microscopy for identification of diabetic sensorimotor polyneuropathy: a pooled multinational consortium study

AIMS/HYPOTHESIS

Small cohort studies raise the hypothesis that corneal nerve abnormalities (including corneal nerve fibre length [CNFL]) are valid non-invasive imaging endpoints for diabetic sensorimotor polyneuropathy (DSP). We aimed to establish concurrent validity and diagnostic thresholds in a large cohort of participants with and without DSP.

METHODS

Nine hundred and ninety-eight participants from five centres (516 with type 1 diabetes and 482 with type 2 diabetes) underwent CNFL quantification and clinical and electrophysiological examination. AUC and diagnostic thresholds were derived and validated in randomly selected samples using receiver operating characteristic analysis. Sensitivity analyses included latent class models to address the issue of imperfect reference standard.

RESULTS

Type 1 and type 2 diabetes subcohorts had mean age of 42 ± 19 and 62 ± 10 years, diabetes duration 21 ± 15 and 12 ± 9 years and DSP prevalence of 31% and 53%, respectively. Derivation AUC for CNFL was 0.77 in type 1 diabetes (p < 0.001) and 0.68 in type 2 diabetes (p < 0.001) and was approximately reproduced in validation sets. The optimal threshold for automated CNFL was 12.5 mm/mm² in type 1 diabetes and 12.3 mm/mm² in type 2 diabetes. In the total cohort, a lower threshold value below 8.6 mm/mm² to rule in DSP and an upper value of 15.3 mm/mm² to rule out DSP were associated with 88% specificity and 88% sensitivity.

CONCLUSIONS/INTERPRETATION

We established the diagnostic validity and common diagnostic thresholds for CNFL in type 1 and type 2 diabetes. Further research must determine to what extent CNFL can be deployed in clinical practice and in clinical trials assessing the efficacy of disease-modifying therapies for DSP.

n-3 Fatty Acid Supplementation for the Treatment of Dry Eye Disease

BACKGROUND

Dry eye disease is a common chronic condition that is characterized by ocular discomfort and visual disturbances that decrease quality of life. Many clinicians recommend the use of supplements of n-3 fatty acids (often called omega-3 fatty acids) to relieve symptoms.

METHODS

In a multicenter, double-blind clinical trial, we randomly assigned patients with moderate-to-severe dry eye disease to receive a daily oral dose of 3000 mg of fish-derived n-3 eicosapentaenoic and docosahexaenoic acids (active supplement group) or an olive oil placebo (placebo group). The primary outcome was the mean change from baseline in the score on the Ocular Surface Disease Index (OSDI; scores range from 0 to 100, with higher scores indicating greater symptom severity), which was based on the mean of scores obtained at 6 and 12 months. Secondary outcomes included mean changes per eye in the conjunctival staining score (ranging from 0 to 6) and the corneal staining score (ranging from 0 to 15), with higher scores indicating more severe damage to the ocular surface, as well as mean changes in the tear break-up time (seconds between a blink and gaps in the tear film) and the result on Schirmer's test (length of wetting of paper strips placed on the lower eyelid), with lower values indicating more severe signs.

RESULTS

A total of 349 patients were assigned to the active supplement group and 186 to the placebo group; the primary analysis included 329 and 170 patients, respectively. The mean change in the OSDI score was not significantly different between the active supplement group and the placebo group (-13.9 points and -12.5 points, respectively; mean difference in change after imputation of missing data, -1.9 points; 95% confidence interval [CI], -5.0 to 1.1; P=0.21). This result was consistent across prespecified subgroups. There were no significant differences between the active supplement group and the placebo group in mean changes from baseline in the conjunctival staining score (mean difference in change, 0.0 points; 95% CI, -0.2 to 0.1), corneal staining score (0.1 point; 95% CI, -0.2 to 0.4), tear break-up time (0.2 seconds; 95% CI, -0.1 to 0.5), and result on Schirmer's test (0.0 mm; 95% CI, -0.8 to 0.9). At 12 months, the rate of adherence to treatment in the active supplement group was 85.2%, according to the level of n-3 fatty acids in red cells. Rates of adverse events were similar in the two trial groups.

CONCLUSIONS

Among patients with dry eye disease, those who were randomly assigned to receive supplements containing 3000 mg of n-3 fatty acids for 12 months did not have significantly better outcomes than those who were assigned to receive placebo. (Funded by the National Eye Institute, National Institutes of Health; DREAM ClinicalTrials.gov number, NCT02128763 .).

Descemet Membrane Endothelial Keratoplasty: Safety and Outcomes: A Report by the American Academy of Ophthalmology

PURPOSE

To review the published literature on the safety and outcomes of Descemet membrane endothelial keratoplasty (DMEK) for the surgical treatment of corneal endothelial dysfunction.

METHODS

Literature searches were last conducted in the PubMed and the Cochrane Library databases most recently in May 2017. The searches, which were limited to English-language abstracts, yielded 1085 articles. The panel reviewed the abstracts, and 47 were determined to be relevant to this assessment.

RESULTS

After DMEK surgery, the mean best-corrected visual acuity (BCVA) ranged from 20/21 to 20/31, with follow-up ranging from 5.7 to 68 months. At 6 months, 37.6% to 85% of eyes achieved BCVA of 20/25 or better and 17% to 67% achieved BCVA of 20/20 or better. Mean endothelial cell (EC) loss was 33% (range, 25%-47%) at 6 months. Overall change in spherical equivalent was +0.43 diopters (D; range, -1.17 to +1.2 D), with minimal induced astigmatism of +0.03 D (range, -0.03 to +1.11 D). The most common complication was partial graft detachment requiring air injection (mean, 28.8%; range, 0.2%-76%). Intraocular pressure elevation was the second most common complication (range, 0%-22%) after DMEK, followed by primary graft failure (mean, 1.7%; range, 0%-12.5%), secondary graft failure (mean, 2.2%; range, 0%-6.3%), and immune rejection (mean, 1.9%; range, 0%-5.9%). Overall graft survival rates after DMEK ranged from 92% to 100% at last follow-up. Best-corrected visual acuity after Descemet's stripping endothelial keratoplasty (DSEK) ranged from 20/34 to 20/66 at 9 months. The most common complications after DSEK were graft detachment (mean, 14%; range, 0%-82%), endothelial rejection (mean, 10%; range, 0%-45%), and primary graft failure (mean, 5%; range, 0%-29%). Mean EC loss after DSEK was 37% at 6 months.

CONCLUSIONS

The evidence reviewed supports DMEK as a safe and effective treatment for endothelial failure. With respect to visual recovery time, visual outcomes, and rejection rates, DMEK seems to be superior to DSEK and to induce less refractive error with similar surgical risks and EC loss compared with DSEK. The rate of air injection and repeat keratoplasty were similar in DMEK and DSEK after the learning curve for DMEK.

Precision of Epithelial Defect Measurements

PURPOSE

To ensure optimal care of patients, cornea specialists measure corneal features, including epithelial defects (ED), with slit-lamp calipers. However, caliper measurements are subject to interphysician variability. We examined the extent of variability in ED measurements between cornea specialists and discuss the potential clinical impact.

METHODS

A total of 48 variably sized EDs were created in pig eyes. Three cornea specialists measured the maximum vertical and horizontal ED lengths to the nearest 10th of a millimeter using slit-lamp microscopy. An absolute difference in ED measurement between cornea specialists of 0.5 mm was chosen to be the a priori threshold for clinical significance and was evaluated by the Wilcoxon signed-rank test. Interrater reliability was assessed by intraclass correlation coefficients.

RESULTS

The average absolute difference in the vertical ED length between pairs of examiners ranged from 0.54 to 0.63 mm, and that of the horizontal ED length ranged from 0.44 to 0.46 mm. These differences in ED measurement were not significantly different from 0.5 mm (all P > 0.06). However, pairs of examiners differed in vertical ED length measurements by >0.5 mm in 44% to 52% of EDs and by >1.0 mm in 13% to 17% of EDs. Pairs of examiners differed in horizontal ED length measurements by >0.5 mm in 31% to 40% of EDs and by >1.0 mm in 10% to 15% of EDs. The intraclass correlation coefficient was 0.85 (95% confidence interval, 0.77-0.91) for vertical and 0.84 (95% confidence interval, 0.74-0.90) for horizontal ED measurements.

CONCLUSIONS

Cornea specialists showed good reliability in the measured EDs; however, depending on the threshold for clinical significance, a nontrivial percentage of cases have high interexaminer clinical variability.

The effect of humidity and temperature on visual outcomes after myopic corneal laser refractive surgery

Objective

To determine whether procedure room environmental conditions are associated with outcomes after myopic laser in situ keratomileusis (LASIK) or laser-assisted keratomileusis (LASEK).

Design

Retrospective chart review.

Participants

Eight hundred sixty-three eyes of 458 consecutive patients at a university-based academic practice.

Methods

We reviewed the medical records of consecutive patients who underwent LASIK or LASEK over a 3-year period. Linear mixed regression models were used to investigate the association of laser room temperature and humidity with the outcomes of visual acuity and postoperative manifest spherical equivalent refraction. Repeated measures logistic regression models were used for the outcomes of diffuse lamellar keratitis (DLK) and need for enhancement surgery.

Results

Subjects were on an average 38.6 years old at the time of surgery (standard deviation [SD] =10.3) and the average spherical equivalent refraction of eyes was 3.8 diopters (SD =2.03). Regression models did not reveal a significant association between temperature and uncorrected distance visual acuity (UDVA) or corrected distance visual acuity (CDVA), or between humidity and UDVA (P>0.05 for all). However, increased humidity was associated with a small but statistically significant improvement in CDVA after LASIK at 1 day, 1 month, 3 months, and 1 year postoperatively (P<0.05 for all). There was no significant association between temperature and humidity and the need for enhancement, the incidence of DLK, or postoperative manifest refraction.

Conclusion

While increased laser room humidity was consistently associated with small improvements in CDVA after myopic LASIK over time, variations in room temperature and humidity were not associated with UDVA, the need for enhancement, the incidence of DLK, or refraction after myopic LASIK or LASEK.

Discordant Dry Eye Disease (An American Ophthalmological Society Thesis)

PURPOSE

To improve understanding of dry eye disease and highlight a subgroup of patients who have a component of central sensitization and neuropathic pain contributing to their condition.

METHODS

Prospective, cross-sectional, IRB-approved study comparing isolated dry eye disease (n=48) to fibromyalgia (positive control; n=23) and healthy (negative control; n=26) individuals with ocular surface examination, corneal confocal microscopy, quantitative sensory testing, and self-reported ocular symptoms and systemic associations. A subset of patients also underwent skin biopsy and/or brain neuroimaging. Dry eye patients were split into concordant (ie, those with dry eyes on examination) and discordant (ie, those with dry eye symptoms but normal examination) subgroups for further analysis. We hypothesized that on the systemic measures included, concordant patients would resemble healthy controls, whereas discordant patients would show evidence of centralized mechanisms similar to fibromyalgia.

RESULTS

Schirmer test and Ocular Surface Disease Index (OSDI) scores indicated significant decreases in tear production (Schirmer: healthy, 18.5±8.2 mm; dry, 11.2±5.4 mm; fibromyalgia, 14.4±7.5; P<.001) and increases in self-reported dry eye symptoms (OSDI: healthy, 1.9±3.0; dry, 20.3±17.7; fibromyalgia, 20.3±17.1; P<.001) in the dry eye and fibromyalgia patients, compared to controls. The discordant subgroup had decreased corneal nerve density and decreased visual quality-of-life scores, similar to patients with fibromyalgia. Concordant patients were more similar to healthy controls on these measures.

CONCLUSIONS

Individuals with discordant dry eye may have a central pathophysiologic mechanism leading to their eye pain symptoms, which could be an important factor to consider in treatment of chronic idiopathic dry eye.

Impact of diagnosing diabetic complications on future hemoglobin A1c levels

AIM

To assess how hemoglobin A1c (HbA1c) values might change following the diagnosis of the first complication from diabetes mellitus (DM).

METHODS

Using a nationwide, longitudinal managed care network claims database (2001-2011), we identified patients with DM who experienced an initial diabetes-related complication. A paired t-test was used to compare average HbA1c levels before the initial complication was first diagnosed to average HbA1c levels following the diagnosis of the complication.

RESULTS

518 enrollees met study inclusion criteria. Patients with suboptimally controlled DM (defined as HbA1c>7% (53 mmol/mol)) prior to the diagnosis of their first diabetic complication demonstrated a clinically significant reduction in average HbA1c following the diagnosis of their first complication (mean pre-complication HbA1c=8.5 ± 1.5% (69 ± 17 mmol/mol) vs. mean post-complication HbA1c=7.9 ± 1.7% (63 ± 18 mmol/mol) (p<0.0001)).

CONCLUSION

Enrollees with suboptimally controlled DM may achieve better glycemic control following the diagnosis of a complication from DM. The results from this study, if confirmed in prospective studies, may provide a rationale for the earlier detection of complications from DM to facilitate improved glycemic control among patients with DM.

Ocular surface disease in patients with diabetic peripheral neuropathy

PURPOSE

To analyse clinical signs and symptoms of ocular surface disease in patients with diabetes mellitus (DM), based on severity of diabetic peripheral neuropathy (DPN).

METHODS

This cross-sectional study included participants who were carefully phenotyped by a multidisciplinary team and categorised into groups based on severity of DPN. All study participants underwent ophthalmic evaluation and completed the Ocular Surface Disease Index (OSDI) and Visual Function Questionnaire (VFQ-25).

RESULTS

The 34 study participants were healthy controls (n=9), patients with DM and mild or no DPN (n=16) and patients with DM and severe DPN (n=9). Tear osmolarity was increased, and corneal nerve fibre length was decreased, with increasing severity of DPN. In addition, patients with DM were found to have decreased Schirmer's test values when compared with healthy controls. No statistically significant differences were found between groups in OSDI, tear breakup time or corneal sensitivity. No statistically significant correlations were noted between the OSDI or VFQ-25 scores and clinical signs of dry eyes.

CONCLUSION

This study demonstrates some increased clinical signs of ocular surface disease but not an increase in subjective symptoms of dry eyes, with increasing severity of DPN. Furthermore, no significant correlation was found between OSDI scores and clinical signs of dry eye. A periodic evaluation of the ocular surface is important for patients with DM, in addition to retinopathy screening, as they may be asymptomatic but have severe dry eye disease, which can lead to further ocular surface complications such as corneal ulceration.

TRIAL REGISTRATION NUMBER

NCT01695629.

Safety and Efficacy of Lacrimal Drainage System Plugs for Dry Eye Syndrome: A Report by the American Academy of Ophthalmology

OBJECTIVE

To review the published literature assessing the efficacy and safety of lacrimal drainage system plug insertion for dry eye in adults.

METHODS

Literature searches of the PubMed and Cochrane Library databases were last conducted on March 9, 2015, without date restrictions and were limited to English language abstracts. The searches retrieved 309 unique citations. The primary authors reviewed the titles and abstracts. Inclusion criteria specified reports that provided original data on plugs for the treatment of dry eyes in at least 25 patients. Fifty-three studies of potential relevance were assigned to full-text review. The 27 studies that met the inclusion criteria underwent data abstraction by the panels. Abstracted data included study characteristics, patient characteristics, plug type, insertion technique, treatment response, and safety information. All studies were observational and rated by a methodologist as level II or III evidence.

RESULTS

The plugs included punctal, intracanalicular, and dissolving types. Fifteen studies reported metrics of improvement in dry eye symptoms, ocular-surface status, artificial tear use, contact lens comfort, and tear break-up time. Twenty-five studies included safety data. Plug placement resulted in ≥50% improvement of symptoms, improvement in ocular-surface health, reduction in artificial tear use, and improved contact lens comfort in patients with dry eye. Serious complications from plugs were infrequent. Plug loss was the most commonly reported problem with punctal plugs, occurring on average in 40% of patients. Overall, among all plug types, approximately 9% of patients experienced epiphora and 10% required removal because of irritation from the plugs. Canaliculitis was the most commonly reported problem for intracanalicular plugs and occurred in approximately 8% of patients. Other complications were reported in less than 4% of patients on average and included tearing, discomfort, pyogenic granuloma, and dacryocystitis.

CONCLUSIONS

On the basis of level II and III evidence in these studies, plugs improve the signs and symptoms of moderate dry eye that are not improved with topical lubrication, and they are well tolerated. There are no level I studies that describe the efficacy or safety of lacrimal drainage system plugs.

Boston Keratoprosthesis: Outcomes and Complications: A Report by the American Academy of Ophthalmology

OBJECTIVE

To review the published literature on safety and outcomes of the Boston type I keratoprosthesis (BI-KPro) for the surgical treatment of corneal opacification not amenable to human cadaveric corneal transplantation.

METHODS

Searches of peer-reviewed literature were conducted in PubMed and the Cochrane Library in December 2012, July 2013, and January 2014 without date restrictions. The searches were limited to studies published in English and yielded 587 citations. The abstracts of these articles were reviewed, 48 articles were selected for possible clinical relevance, and 22 were determined to be relevant for the assessment objectives. Nine studies were rated as level II evidence and 13 studies were rated as level III evidence. Excluded were level III evidence, case reports, review articles, letters, editorials, and case series with fewer than 25 eyes.

RESULTS

In 9 articles, a best-corrected Snellen visual acuity (BCSVA) of 20/200 or better occurred in 45% to 89% of eyes. Five articles described a BCSVA of 20/50 or better in 43% to 69% of eyes, and 4 articles found a BCSVA of 20/40 or better in 11% to 39% of eyes. Retention rates of the BI-KPro ranged from 65% to 100%. Reasons for loss of vision after BI-KPro implantation most commonly included corneal melts resulting from exposure keratopathy, endophthalmitis, and infectious keratitis or corneal ulceration. The 2 most common complications after surgery were retroprosthetic membrane formation (range, 1.0%-65.0%; mean ± standard deviation [SD], 30.0±19.0%) and elevated intraocular pressure (range, 2.4%-64.0%; mean ± SD, 27.5±18.1%). The 2 most common posterior segment complications were endophthalmitis (range, 0%-12.5%; mean ± SD, 4.6±4.6%) and vitritis (range, 0%-14.5%; mean ± SD, 5.6±4.7%).

CONCLUSIONS

The reviewed articles on BI-KPro use suggest that the device improves vision in cases of severe corneal opacification that were not amenable to corneal transplantation using human cadaveric keratoplasty techniques. A number of severe anterior and posterior segment complications can develop as follow-up continues, making ongoing close observation paramount for patients undergoing this surgery. These complications include infection, device extrusion, and permanent vision loss.

Long-term use of autologous serum 50% eye drops for the treatment of dry eye disease

PURPOSE

The aim of this study was to describe the outcomes of 50% autologous serum (AS) eye drops after long-term use in a large cohort of patients with dry eyes.

METHODS

A retrospective cohort study was conducted on all patients treated with 50% AS eye drops at our institution between June 2008 and January 2013. Records were reviewed for clinical history, systemic risk factors, dry eye etiology, patients' symptoms, and adverse events. Ocular surface evaluation included Schirmer testing with topical anesthesia, fluorescein staining, and ocular surface disease index. Data were reviewed at initial visit, 1 month, and every 3 to 6 months during treatment with AS. Paired t tests were performed to compare the progression of signs and symptoms of dry eye disease.

RESULTS

A total of 123 eyes of 63 patients were evaluated with a mean follow-up of 12 months (range, 3-48 months). Corneal fluorescein staining (mean baseline, 1.77 ± 1.1) improved at the 3- to <6-month, 6- to <12-month, and final follow-up (mean: 1.2 ± 1.0, 1.3 ± 1.0, and 1.1 ± 1.1; P = 0.003, 0.017, and 0.0003, respectively). Schirmer scores (mean baseline, 6.6 ± 6.5 mm) improved at the 12- to 24-month follow-up (mean = 10.7 ± 11.4, P = 0.03), whereas ocular surface disease index scores (mean baseline, 54.1 ± 22.3) improved at the 3- to <6- and 6- to <12-month follow-up (mean: 49.5 ± 8.2 and 39.3 ± 21.4, P = 0.029 and 0.003, respectively). No complications were noted.

CONCLUSIONS

Fifty percent AS eye drops seem to be a safe and effective long-term treatment for dry eye disease, especially in patients with severe disease who have exhausted all other conventional forms of treatment.

Mitomycin-C in corneal surface excimer laser ablation techniques: a report by the American Academy of Ophthalmology

OBJECTIVE

To review the published literature assessing the efficacy and safety of mitomycin-C (MMC) as an adjunctive treatment in corneal surface excimer laser ablation procedures.

METHODS

Literature searches of the PubMed and Cochrane Library databases were last conducted on August 19, 2014, without language or date limitations. The searches retrieved a total of 239 references. Of these, members of the Ophthalmic Technology Assessment Committee Refractive Management/Intervention Panel selected 26 articles that were considered to be of high or medium clinical relevance, and the panel methodologist rated each article according to the strength of evidence. Ten studies were rated as level I evidence, 5 studies were rated as level II evidence, and the remaining 11 studies were rated as level III evidence.

RESULTS

The majority of the articles surveyed in this report support the role of MMC as an adjunctive treatment in surface ablation procedures. When MMC is applied in the appropriate concentration and confined to the central cornea, the incidence of post-surface ablation haze is decreased. Although a minority of studies that evaluated endothelial cell density (ECD) reported an MMC-related decrease in ECD, no clinical adverse outcomes were reported.

CONCLUSIONS

Over the past 15 years, the use of MMC during surgery in surface ablation has become widespread. There is good evidence of the effectiveness of MMC when used intraoperatively as prophylaxis against haze in higher myopic ablations. Although there are reports of decreased endothelial counts after the administration of MMC during surgery, the clinical significance of this finding remains uncertain, because no adverse outcomes were reported with as much as 5 years of follow-up. Optimal dosage, effectiveness as prophylaxis in lower myopic and hyperopic ablations, and long-term safety, particularly in eyes with reduced corneal endothelial cell counts from prior intraocular surgery, have yet to be established.

Corneal donor tissue preparation for Descemet's membrane endothelial keratoplasty

Descemet's Membrane Endothelial Keratoplasty (DMEK) is a form of corneal transplantation in which only a single cell layer, the corneal endothelium, along with its basement membrane (Descemet's membrane) is introduced onto the recipient's posterior stroma(3). Unlike Descemet's Stripping Automated Endothelial Keratoplasty (DSAEK), where additional donor stroma is introduced, no unnatural stroma-to-stroma interface is created. As a result, the natural anatomy of the cornea is preserved as much as possible allowing for improved recovery time and visual acuity(4). Endothelial Keratoplasty (EK) is the procedure of choice for treatment of endothelial dysfunction. The advantages of EK include rapid recovery of vision, preservation of ocular integrity and minimal refractive change due to use of a small, peripheral incision(1). DSAEK utilizes donor tissue prepared with partial thickness stroma and endothelium. The rapid success and utilization of this procedure can be attributed to availability of eye-bank prepared precut tissue. The benefits of eye-bank preparation of donor tissue include elimination of need for specialized equipment in the operating room and availability of back up donor tissue in case of tissue perforation during preparation. In addition, high volume preparation of donor tissue by eye-bank technicians may provide improved quality of donor tissue. DSAEK may have limited best corrected visual acuity due to creation of a stromal interface between the donor and recipient cornea. Elimination of this interface with transplantation of only donor Descemet's membrane and endothelium in DMEK may improve visual outcomes and reduce complications after EK(5). Similar to DSAEK, long term success and acceptance of DMEK is dependent on ease of availability of precut, eye-bank prepared donor tissue. Here we present a stepwise approach to donor tissue preparation which may reduce some barriers eye-banks face in providing DMEK grafts.

Differential reduction in corneal nerve fiber length in patients with type 1 or type 2 diabetes mellitus

AIM

To examine the relationship between corneal nerve fiber length (CNFL) and diabetic neuropathy (DN) status in patients with type 1 or type 2 diabetes mellitus (DM).

METHODS

In this cross-sectional study, we examined 25 diabetic patients without DN, 10 patients with mild DN, 8 patients with severe DN, and 9 controls without diabetes. DN status was assigned based on a combination of clinical symptoms, signs, and electrophysiological testing. Patients underwent corneal confocal microscopy (CCM) of the sub-basal nerve plexus. Post-hoc analysis of the CCM images was performed to quantify the average CNFL, and ANOVA was used to assess for differences in CNFL.

RESULTS

All 25 subjects without DN had type 1 DM, and subjects with DN had type 2 DM. Participants with severe DN had significantly lower CNFL (12.5±6.1mm/mm(2)) compared to controls (20.7±2.2mm/mm(2)) (p=0.009). However, lower CNFL was also found in participants with type 1 DM who did not have DN (15.1±4.7mm/mm(2)) relative to controls (p=0.033).

CONCLUSIONS

CCM of the sub-basal nerve plexus may be an indicator of early peripheral nerve degeneration in type 1 DM. Type of diabetes, in addition to degree of neuropathy, may influence the extent of corneal nerve damage.

Effect of tamsulosin on iris vasculature and morphology

PURPOSE

To determine whether preoperative iris vasculature and morphology are altered in patients who have taken tamsulosin (Flomax).

SETTING

Academic multispecialty practice.

DESIGN

Case series.

METHODS

Patients with current or past tamsulosin use and age- and sex-matched control patients were included. Anterior segment optical coherence tomography (AS-OCT) and iris fluorescein angiography were performed to measure iris vasculature and thickness before cataract surgery. Data collected at surgery included pupil diameter, clinical signs of intraoperative floppy-iris syndrome, and surgical complications.

RESULTS

Tamsulosin was currently used by 16 patients and in the past by 4 patients; the control group comprised 10 patients. Pharmacologically dilated pupil diameter was statistically significantly smaller preoperatively and immediately postoperatively in the tamsulosin group than in the control group (P=.009 and P=.003, respectively). There was a statistically significant decrease in pupil size intraoperatively in the tamsulosin group (P=.05) but not in the control group (P=.3). Iris-vasculature parameters, specifically time to first vessel fill and percentage of vessel fill on iris fluorescein angiography, were not significantly different between the 2 groups. The AS-OCT measurements of iris morphology were not statistically significantly different between the groups. No surgical complications occurred. No fluorescein dye leakage, staining, or other vascular anomalies were observed.

CONCLUSIONS

Although there were differences in pupil measurements and intraoperative iris behavior between patients who had been on tamsulosin and control patients, there were no significant differences in iris vasculature on iris fluorescein angiography or in iris morphology on AS-OCT.

Post-LASIK dry eye

Laser-assisted in situ keratomileusis (LASIK) is a frequently performed corneal refractive surgery with excellent refractive outcomes. The most common complication of LASIK is dry eyes, with virtually all patients developing some degree of dryness in the immediate postoperative period. Identifying preoperative dry eyes, and conscientious attention and treatment in the perioperative time period, can lead to enhanced patient satisfaction and more accurate visual outcomes. Improved understanding of the development of dry eyes after LASIK will advance our understanding of the complex pathophysiology of dry eye disease.

Herpes simplex virus keratitis: histopathology and corneal allograft outcomes

Molecular biologic studies have elucidated the roles of specific and innate immune responses in the pathogenesis of HSV keratitis. Recent evidence suggests that interference with innate immune mechanisms may reduce the severity of HSV keratitis and its complications. The agents targeting innate immune responses are particularly amenable to translational therapy for patients at risk of complications of HSV keratitis and poor corneal transplant outcomes. Histopathologic evidence of neovascularization or inflammation in tissue removed at the time of corneal transplantation predicts patients who are at risk for allograft rejection or failure. Such patients are prime candidates for close monitoring and intensive therapy. Newer imaging techniques, such as clinical confocal biomicroscopy, might be useful in identifying neovascularization and inflammation that place patients at high risk for poor allograft outcomes prior to corneal transplantation.

Using an ultrasound elasticity microscope to map three-dimensional strain in a porcine cornea

An ultrasound elasticity microscope was used to map 3-D strain volume in an ex vivo porcine cornea to illustrate its ability to measure the mechanical properties of this tissue. Mechanical properties of the cornea play an important role in its function and, therefore, also in ophthalmic diseases such as kerataconus and corneal ectasia. The ultrasound elasticity microscope combines a tightly focused high-frequency transducer with confocal scanning to produce high-quality speckle over the entire volume of tissue. This system and the analysis were able to generate volume maps of compressional strain in all three directions for porcine corneal tissue, more information than any previous study has reported. Strain volume maps indicated features of the cornea and mechanical behavior as expected. These results constitute a step toward better understanding of corneal mechanics and better treatment of corneal diseases.

Comparative cost-effectiveness analysis of descemet stripping automated endothelial keratoplasty versus penetrating keratoplasty in the United States

PURPOSE

To perform a comparative cost-effectiveness analysis of Descemet stripping automated endothelial keratoplasty (DSAEK) and penetrating keratoplasty (PK) for corneal endothelial disease.

DESIGN

Retrospective cost-effectiveness analysis.

METHODS

This cost-effectiveness analysis was performed from a third-party payer perspective with a 5-year time horizon. Probabilities of outcomes and complications of each of the procedures were calculated based on review of the published literature. A model was constructed to compare the costs and utilities associated with DSAEK and PK. Costs of donor tissue preparation, surgery, follow-up, postoperative complications, and procedures were considered. Utility values were based on quality-adjusted life years associated with visual acuity outcomes. Both costs and utilities were discounted at 3% per year. Sensitivity analyses were performed on key model inputs.

RESULTS

Base case analysis found DSAEK to be less costly compared with PK ($9362 vs $10 239), with greater utility (3.15 vs 2.47 quality-adjusted life years). Sensitivity analyses revealed that even at graft failure rates for DSAEK approaching the rates for PK, DSAEK would still reduce costs. Varying the dislocation rate in our model showed that even at dislocation rates approaching 50%, DSAEK remained less costly. Further, with DSAEK rejection rates as high as 28%, DSAEK would remain a dominant procedure over PK.

CONCLUSIONS

Comparative cost-effectiveness analysis of DSAEK versus PK indicates favorable cost and utility outcomes associated with DSAEK for treatment of corneal endothelial disease. Longer follow-up of DSAEK outcomes will provide more accurate information regarding long-term cost-effectiveness of the procedure.

Femtosecond Lasers in Ophthalmology

The use of the femtosecond laser in ophthalmic surgery over the last decade has resulted in the development of innovative procedures. The ultra-short infrared laser pulses of the femtosecond laser can be applied precisely and predictably with minimal collateral tissue damage, making it an ideal tool for highly precise ophthalmic surgery. Flap creation in laserin situkeratomileusis (LASIK) is the most common use of this laser. It can also be used for other corneal refractive procedures, lamellar and full-thickness corneal transplantation, and cataract surgery. This article summarizes recent advanced applying femtosecond laser technology in ophthalmology.

Corneal donor tissue preparation for endothelial keratoplasty

Over the past ten years, corneal transplantation surgical techniques have undergone revolutionary changes^1,2. Since its inception, traditional full thickness corneal transplantation has been the treatment to restore sight in those limited by corneal disease. Some disadvantages to this approach include a high degree of post-operative astigmatism, lack of predictable refractive outcome, and disturbance to the ocular surface. The development of Descemet's stripping endothelial keratoplasty (DSEK), transplanting only the posterior corneal stroma, Descemet's membrane, and endothelium, has dramatically changed treatment of corneal endothelial disease. DSEK is performed through a smaller incision; this technique avoids 'open sky' surgery with its risk of hemorrhage or expulsion, decreases the incidence of postoperative wound dehiscence, reduces unpredictable refractive outcomes, and may decrease the rate of transplant rejection^3-6.

Initially, cornea donor posterior lamellar dissection for DSEK was performed manually¹ resulting in variable graft thickness and damage to the delicate corneal endothelial tissue during tissue processing. Automated lamellar dissection (Descemet's stripping automated endothelial keratoplasty, DSAEK) was developed to address these issues. Automated dissection utilizes the same technology as LASIK corneal flap creation with a mechanical microkeratome blade that helps to create uniform and thin tissue grafts for DSAEK surgery with minimal corneal endothelial cell loss in tissue processing.

Eye banks have been providing full thickness corneas for surgical transplantation for many years. In 2006, eye banks began to develop methodologies for supplying precut corneal tissue for endothelial keratoplasty. With the input of corneal surgeons, eye banks have developed thorough protocols to safely and effectively prepare posterior lamellar tissue for DSAEK surgery. This can be performed preoperatively at the eye bank. Research shows no significant difference in terms of the quality of the tissue⁷ or patient outcomes^8,9 using eye bank precut tissue versus surgeon-prepared tissue for DSAEK surgery. For most corneal surgeons, the availability of precut DSAEK corneal tissue saves time and money¹⁰, and reduces the stress of performing the donor corneal dissection in the operating room. In part because of the ability of the eye banks to provide high quality posterior lamellar corneal in a timely manner, DSAEK has become the standard of care for surgical management of corneal endothelial disease.

The procedure that we are describing is the preparation of the posterior lamellar cornea at the eye bank for transplantation in DSAEK surgery (Figure 1).

In vivo confocal microscopic evaluation of corneal wound healing after femtosecond laser-assisted keratoplasty

BACKGROUND AND OBJECTIVE

To evaluate corneal wound healing after femtosecond laser-assisted keratoplasty (FLAK) using in vivo confocal microscopy (IVCM).

PATIENTS AND METHODS

Prospective, interventional, consecutive case series of 17 eyes after mushroom-shaped FLAK. IVCM was performed preoperatively and at 1, 3, 6, and 12 months postoperatively to assess wound healing.

RESULTS

Mean keratocyte activation grade increased from preoperative levels to 1 month postoperatively in both the central (0.41 ± 0.62 to 1.73 ± 1.03) and peripheral (0.47 ± 0.52 to 1.57 ± 1.09) cornea, then gradually decreased through 12 months. Dendritic cells increased from preoperatively to 1 month postoperatively in both the central (0.71 ± 0.83 to 1.33 ± 0.98) and peripheral (0.79 ± 0.70 to 1.42 ± 0.90) cornea, then gradually decreased until 6 months postoperatively. Stromal reinnervation was 1 month postoperatively in 8 patients (50%). By 12 months, sub-epithelial nerves were observed centrally in 5 patients (45.5%).

CONCLUSION

IVCM after FLAK shows an initial increase in keratocyte activation and dendritic cells that decrease over time. Corneal reinnervation is seen as early as 1 month postoperatively.

Incidence of diffuse lamellar keratitis after LASIK with 15 KHz, 30 KHz, and 60 KHz femtosecond laser flap creation

PURPOSE

To compare the incidence of diffuse lamellar keratitis (DLK) after laser in situ keratomileusis (LASIK) with flap creation using the 15 kHz (FS15), 30 kHz (FS30), or 60 kHz (FS60) femtosecond laser.

SETTING

University-based academic practice, Ann Arbor, Michigan, USA.

DESIGN

Retrospective comparative case series.

METHODS

Consecutive myopic LASIK cases performed between January 1, 2005, and June 1, 2007, using the IntraLase FS15, FS30, or FS60 femtosecond laser for flap creation were reviewed. Preoperative clinical characteristics, treatment parameters, and intraoperative and postoperative complications were recorded. Statistical comparisons were made using repeated measures analysis, analysis of variance, chi-square, and Fisher exact tests.

RESULTS

Five hundred twenty eyes of 274 patients were included in the study. One hundred seventy-six eyes (93 patients) were treated with the FS15 laser, 180 eyes (93 patients) with the FS30 laser, and 164 eyes (89 patients) with the FS60 laser. Seventeen eyes (10%) in the FS15 laser group, 24 eyes (13%) in the FS30 laser group, and 23 eyes (14%) in the FS60 laser group developed DLK. There was no statistically significant difference in the incidence of DLK between the 3 groups (P = .68).

CONCLUSION

There was no significant difference in the incidence of DLK between the FS15, FS30, and FS60 groups.