Pathological-Corneas Layer Segmentation and Thickness Measurement in OCT Images.

Purpose: The purpose of this study was to propose a new algorithm for the segmentation and thickness measurement of pathological corneas with irregular layers using a two-stage graph search and ray tracing. Methods: In the first stage, a graph, with only gradient edge-cost, is used to segment the air-epithelium and endothelium-aqueous boundaries. In the second stage, a graph, with gradient, directional, and multiplier edge-cost, is used to correct segmentation. The optical coherence tomography (OCT) image is flattened using the air-epithelium boundary and a graph search is used to segment the epithelium-Bowman's and Bowman's-stroma boundaries. Then, the OCT image is flattened using the endothelium-aqueous boundary and a graph search is used to segment the Descemet's membrane. Ray tracing is used to correct the inter-boundary distances, then the thickness is measured using the shortest distance. The proposed algorithm was trained and evaluated using 190 OCT images manually segmented by trained operators. Results: The mean and standard deviation of the unsigned errors of the algorithm-operator and inter-operator were 0.89 ± 1.03 and 0.77 ± 0.68 pixels in segmentation and 3.62 ± 3.98 and 2.95 ± 2.52 µm in thickness measurement. Conclusions: Our proposed algorithm can produce accurate segmentation and thickness measurements compared with the manual operators. Translational Relevance: Our algorithm could be potentially useful in the clinical practice.

Mobility improvement of patients with peripheral visual field losses using novel see-through digital spectacles.

PURPOSE: To evaluate see-through Augmented Reality Digital spectacles (AR DSpecs) for improving the mobility of patients with peripheral visual field (VF) losses when tested on a walking track. DESIGN: Prospective Case Series. PARTICIPANTS: 21 patients with peripheral VF defects in both eyes, with the physical ability to walk without assistance. METHODS: We developed the AR DSpecs as a wearable VF aid with an augmented reality platform. Image remapping algorithms produced personalized visual augmentation in real time based on the measured binocular VF with the AR DSpecs calibration mode. We tested the device on a walking track to determine if patients could more accurately identify peripheral objects. MAIN OUTCOME MEASURES: We analyzed walking track scores (number of recognized/avoided objects) and eye tracking data (six gaze parameters) to measure changes in the kinematic and eye scanning behaviors while walking, and assessed a possible placebo effect by deactivating the AR DSpecs remapping algorithms in random trials. RESULTS: Performance, judged by the object detection scores, improved with the AR DSpecs (P<0.001, Wilcoxon rank sum test) with an average improvement rate of 18.81%. Two gaze parameters improved with the activated algorithm (P<0.01, paired t-test), indicating a more directed gaze on the central path with less eye scanning. Determination of the binocular integrated VF with the DSpecs correlated with the integrated standard automated perimetry (R = 0.86, P<0.001), mean sensitivity difference 0.8 ± 2.25 dB (Bland-Altman). CONCLUSIONS: AR DSpecs may improve walking maneuverability of patients with peripheral VF defects by enhancing detection of objects in a testing environment.

Diagnostic Performance of 3-Dimensional Thickness of the Endothelium-Descemet Complex in Fuchs' Endothelial Cell Corneal Dystrophy.

PURPOSE: To describe the diagnostic accuracy of 3-dimensional (3D) endothelium-Descemet's membrane complex thickness (En-DMT) in Fuchs' endothelial corneal dystrophy (FECD) and determine its potential role as an objective index of disease severity. DESIGN: Observational case-control study. PARTICIPANTS: One hundred four eyes of 79 participants (64 eyes of 41 FECD patients and 40 eyes of 38 healthy controls). METHODS: All participants received high-definition OCT imaging (Envisu R2210; Bioptigen, Buffalo Grove, IL). Fuchs' endothelial corneal dystrophy was classified clinically into early-stage (without edema) and late-stage (with edema) disease. Automatic and manual segmentation of corneal layers was performed using a custom-built segmental tomography algorithm to generate 3D maps of total corneal thickness (TCT) and En-DMT of the central 6-mm cornea. Regional En-DMT, regional TCT, and central-to-peripheral total corneal thickness ratio (CPTR) were evaluated and correlated to the clinical severity of FECD. Intraclass correlation coefficients (ICCs) and Bland-Altman plots were used to assess the reliability of the repeated measurements in all eyes. MAIN OUTCOME MEASURES: Central-to-peripheral total corneal thickness ratio and average En-DMT and TCT of central, paracentral, and peripheral regions. RESULTS: In FECD, a significant increase in En-DMT, CPTR, and TCT was found compared to controls (P < 0.001). For identifying FECD, average En-DMT of paracentral and peripheral regions achieved 94% sensitivity and 100% specificity (cutoffs, 19 µm and 20 µm, respectively), whereas CPTR showed 94% sensitivity with a 73% specificity (cutoff, 0.97). Regarding early-stage FECD, average En-DMT of central zones achieved 92% sensitivity and 97% specificity (cutoff, 18 µm), whereas CPTR showed 90% sensitivity and 88% specificity (cutoff, 0.97). The average En-DMT of central, paracentral, and peripheral regions was correlated highly with FECD clinical stage (Spearman's ρ = 0.813, 0.793, and 0.721, respectively; all P < 0.001), compared with CPTR and mean TCT of paracentral zones (0.672 and 0.481, respectively; P < 0.001). The ICC values ranged from 0.98 (En-DMT) to 0.99 (TCT) with a good agreement between the automatic and manual measurements. CONCLUSIONS: Regional 3D En-DMT is a novel diagnostic tool of FECD that can be used to quantify the disease severity with excellent reliability.

Automatic Segmentation of Corneal Microlayers on Optical Coherence Tomography Images.

PURPOSE: To propose automatic segmentation algorithm (AUS) for corneal microlayers on optical coherence tomography (OCT) images. METHODS: Eighty-two corneal OCT scans were obtained from 45 patients with normal and abnormal corneas. Three testing data sets totaling 75 OCT images were randomly selected. Initially, corneal epithelium and endothelium microlayers are estimated using a corneal mask and locally refined to obtain final segmentation. Flat-epithelium and flat-endothelium images are obtained and vertically projected to locate inner corneal microlayers. Inner microlayers are estimated by translating epithelium and endothelium microlayers to detected locations then refined to obtain final segmentation. Images were segmented by trained manual operators (TMOs) and by the algorithm to assess repeatability (i.e., intraoperator error), reproducibility (i.e., interoperator and segmentation errors), and running time. A random masked subjective test was conducted by corneal specialists to subjectively grade the segmentation algorithm. RESULTS: Compared with the TMOs, the AUS had significantly less mean intraoperator error (0.53 ± 1.80 vs. 2.32 ± 2.39 pixels; P < 0.0001), it had significantly different mean segmentation error (3.44 ± 3.46 vs. 2.93 ± 3.02 pixels; P < 0.0001), and it had significantly less running time per image (0.19 ± 0.07 vs. 193.95 ± 194.53 seconds; P < 0.0001). The AUS had insignificant subjective grading for microlayer-segmentation grading (4.94 ± 0.32 vs. 4.96 ± 0.24; P = 0.5081), but it had significant subjective grading for regional-segmentation grading (4.96 ± 0.26 vs. 4.79 ± 0.60; P = 0.025). CONCLUSIONS: The AUS can reproduce the manual segmentation of corneal microlayers with comparable accuracy in almost real-time and with significantly better repeatability. TRANSLATIONAL RELEVANCE: The AUS can be useful in clinical settings and can aid the diagnosis of corneal diseases by measuring thickness of segmented corneal microlayers.

Comparison of endothelial/Descemet's membrane complex thickness with endothelial cell density for the diagnosis of corneal transplant rejection.

PURPOSE: This study compared the effectiveness of endothelial/Descemet's membrane complex thickness obtained using high-definition anterior segment optical coherence tomography with endothelial cell density obtained using confocal microscopy as diagnostic tools in predicting corneal transplant rejection. METHODS: This observational, prospective, cross-sectional study evaluated penetrating keratoplasty grafts. Slit lamp examination organized the grafts into healthy or rejecting grafts. Grafts were scanned using both high-definition anterior segment optical coherence tomography and confocal microscopy. Central corneal thickness, endothelial/Descemet's membrane complex thickness, endothelial cell density, and coefficient of variation were each compared with the clinical status. Descemet's rejection index, defined by endothelial/Descemet's membrane complex thickness divided by central corneal thickness multiplied by 33, further compared endothelial/Descemet's membrane complex thickness with central corneal thickness. RESULTS: Endothelial/Descemet's membrane complex thickness, central corneal thickness, and Descemet's rejection index were all able to differentiate between clear and rejected corneal grafts (p < 0.0001, p = 0.001, and p = 0.012, respectively). Endothelial cell density and coefficient of variation did not correlate with the clinical status (p = 0.054 and p = 0.102, respectively). Endothelial/Descemet's membrane complex thickness had the largest area under the curve using receiver operating characteristic curves (p < 0.0001). Endothelial/Descemet's membrane complex thickness had a sensitivity of 86% and specificity of 81% with a cutoff value of >16.0 µm (p < 0.0001). The sensitivity and specificity of endothelial cell density were both 71% with a cutoff value of ⩽897 cells/mm2 (p = 0.053). There was a high correlation between endothelial/Descemet's membrane complex thickness and both Descemet's rejection index and central corneal thickness (p < 0.0001). CONCLUSION: Endothelial/Descemet's membrane complex thickness measured by high-definition anterior segment optical coherence tomography is a useful parameter for the diagnosis of corneal graft rejection. The diagnostic performance of endothelial/Descemet's membrane complex thickness was significantly better than that of endothelial cell density and central corneal thickness. Endothelial cell density and the coefficient of variation were unable to diagnose corneal graft rejection in our cross-sectional study.

Combined conjunctival autograft and overlay amniotic membrane transplantation; a novel surgical treatment for pterygium.

The authors report the long-term results of combined conjunctival autograft and overlay amniotic membrane transplantation (AMT) for treatment of pterygium as a new surgical technique. Nineteen patients including 12 male and 7 female subjects with pterygium (primary, 14 cases; recurrent, 5 cases) underwent combined conjunctival autograft and overlay AMT and were followed from 10 to 26 months. Mean age was 44.21±12.49 (range, 29.0-73.0) years. In one patient with grade T3 primary pterygium, the lesion recurred (5.2%, recurrence rate). No intra-and postoperative complication developed. This procedure seems a safe and effective surgical technique for pterygium treatment. Protection of the ocular surface during the early postoperative period reduces the friction-induced inflammation and might be helpful to prevent the recurrence.

Diagnosis of ocular surface lesions using ultra-high-resolution optical coherence tomography.

PURPOSE: To assess the use of ultra-high-resolution (UHR) optical coherence tomography (OCT) in the diagnosis of ocular surface lesions. DESIGN: Prospective, noncomparative, interventional case series. PARTICIPANTS: Fifty-four eyes of 53 consecutive patients with biopsy-proven ocular surface lesions: 8 primary acquired melanosis lesions, 5 amelanotic melanoma lesions, 2 nevi, 19 ocular surface squamous neoplasia lesions, 1 histiocytosis lesion, 6 conjunctival lymphoma lesions, 2 conjunctival amyloidosis lesions, and 11 pterygia lesions. INTERVENTION: Ultra-high-resolution OCT imaging of the ocular surface lesions. MAIN OUTCOME MEASURES: Clinical course and photographs, UHR OCT image, and histopathologic findings. RESULTS: Ultra-high-resolution OCT images of all examined ocular surface lesions showed close correlation with the obtained histopathologic specimens. When clinical differential diagnosis of ocular surface lesions was broad, UHR OCT images provided optical signs indicating a more specific diagnosis and management. In cases of amelanotic melanoma, conjunctival amyloidosis, and primary histiocytosis and in 1 case of ocular surface squamous neoplasia, UHR OCT was instrumental in guiding the diagnosis. In those cases, UHR OCT suggested that the presumed clinical diagnosis was incorrect and favored a diagnosis that later was confirmed by histopathologic examination. CONCLUSIONS: Correlations between UHR OCT and histopathologic findings confirm that UHR OCT is an adjunctive diagnostic method that can provide a noninvasive means to help guide diagnosis and management of ocular surface lesions. FINANCIAL DISCLOSURE(S): The author(s) have no proprietary or commercial interest in any materials discussed in this article.

Quality of corneal lamellar cuts quantified using atomic force microscopy.

PURPOSE: To quantify the cut quality of lamellar dissections made with the femtosecond laser using atomic force microscopy (AFM). SETTING: Bascom Palmer Eye Institute, University of Miami Miller School of Medicine, Miami, Florida, USA. DESIGN: Experimental study. METHODS: Experiments were performed on 3 pairs of human cadaver eyes. The cornea was thinned to physiologic levels by placing the globe, cornea side down, in 25% dextran for 24 hours. The eyes were reinflated to normal pressures by injecting a balanced salt solution into the vitreous cavity. The eyes were placed in a holder, the epithelium was removed, and the eyes were cut with a Visumax femtosecond laser. The energy level was 180 nJ for the right eye and 340 nJ for the left eye of each pair. The cut depths were 200 µm, 300 µm, and 400 µm, with the cut depth maintained for both eyes of each pair. A 12.0 mm trephination was then performed. The anterior portion of the lamellar surface was placed in a balanced salt solution and imaged with AFM. As a control, the posterior surface was placed in 2% formalin and imaged with environmental scanning electron microscopy (SEM). Four quantitative parameters (root-mean-square deviation, average deviation, skewness, kurtosis) were calculated from the AFM images. RESULTS: From AFM, the 300 µm low-energy cuts were the smoothest. Similar results were seen qualitatively in the environmental SEM images. CONCLUSION: Atomic force microscopy provided quantitative information on the quality of lamellar dissections made using a femtosecond laser, which is useful in optimizing patient outcomes in refractive and lamellar keratoplasty surgeries.

Diagnosis and management of conjunctival and corneal intraepithelial neoplasia using ultra high-resolution optical coherence tomography.

PURPOSE: To report a novel diagnostic technique and a case series of conjunctival and corneal intraepithelial neoplasia (CCIN) diagnosed and followed up using prototype ultra high-resolution (UHR) optical coherence tomography (OCT). DESIGN: Prospective, noncomparative, interventional case series. PARTICIPANTS: Seven eyes of 7 consecutive patients with CCIN treated using topical interferon alfa-2b or 5-fluorouracil and 7 eyes of 6 consecutive patients with history of surgically excised pterygia. INTERVENTION: Ultra high-resolution OCT imaging of the ocular surface at primary diagnosis of CCIN and during the follow-up period until resolution of the lesion. Ultra high-resolution OCT images of sites of excised pterygia also were captured and compared with images from resolved CCIN patients. MAIN OUTCOME MEASURES: Clinical course and photographs, UHR OCT images, and histopathologic findings. RESULTS: Ultra high-resolution OCT was capable of providing a noninvasive optical biopsy of all examined CCIN lesions. Ultra high-resolution OCT images of the lesions disclosed a thickened hyperreflective epithelium and abrupt transition from normal to hyperreflective epithelium in all 7 cases. Ultra high-resolution OCT images showed excellent correlation with histopathologic specimens obtained at primary diagnosis of the cases that had incisional biopsies before treatment. All patients were treated medically and were followed up for clinical resolution. In 4 patients, at clinical resolution, UHR OCT images also showed normal epithelial configuration at the site of the treated lesions. In 3 patients, despite apparent clinical resolution, the UHR OCT was able to detect residual disease that was clinically invisible. Continuation of treatment resulted in complete resolution of the residual lesions on the UHR OCT images in all cases. Ultra high-resolution OCT images of patients with surgically excised pterygia demonstrated similar findings to resolved CCIN cases. CONCLUSIONS: Ultra high-resolution OCT is a novel noninvasive technique to diagnose and manage medically treated CCIN. Using UHR OCT to guide medical treatment could prevent the premature termination of topical treatment in the presence of subclinical disease. A larger sample size is needed for further validation of its sensitivity and specificity. FINANCIAL DISCLOSURE(S): The author(s) have no proprietary or commercial interest in any materials discussed in this article.

Topographic thickness of Bowman's layer determined by ultra-high resolution spectral domain-optical coherence tomography.

PURPOSE: To characterize the thickness profile of the corneal epithelium and the Bowman's layer across the horizontal meridian. METHODS: Forty-four eyes of 22 healthy subjects were investigated in this study. Ultra-high resolution anterior segment spectral domain-optical coherence tomography (SD-OCT) was used to assess the topographic thickness of the epithelium and the Bowman's layer across the cornea. Thicknesses at five locations, including the center, midperiphery, and periphery close to the limbus, on both the nasal and the temporal sides along the horizontal meridian, were analyzed. RESULTS: Mean epithelial thickness at the central cornea was 52.5 ± 2.4 µm. It increased gradually from the center to the periphery (P < 0.001). There was no significant difference between the nasal side and the temporal side for epithelial thickness. The central Bowman's layer thickness was 17.7 ± 1.6 µm, and it remained constant from the center to the midperiphery (P > 0.05). However, thicknesses at the nasal and temporal periphery, 20.0 ± 1.9 µm and 19.8 ± 2.2 µm, respectively, were significantly greater than the central and midperipheral thicknesses (P < 0.001). Nasal and temporal thicknesses were similar on either side of the center. CONCLUSIONS: The epithelium and the Bowman's layer were not evenly distributed across the horizontal meridian of the cornea. SD-OCT provided useful information about topographic thickness of the different corneal layers in vivo.

Ultra high-resolution anterior segment optical coherence tomography in the evaluation of anterior corneal dystrophies and degenerations.

PURPOSE: To evaluate the clinical usefulness of a spectral-domain ultra high-resolution anterior segment optical coherence tomography (UHR OCT) in examination, diagnosis, and management of various anterior corneal dystrophies and degenerations. DESIGN: Noncomparative case series. PARTICIPANTS: Fifty-nine eyes of 38 consecutive patients were enrolled in the study and included 28 eyes of 14 patients with anterior corneal dystrophies, 21 eyes of 19 patients with anterior corneal degenerations or neoplasia, and 10 eyes of 5 patients with normal corneas. METHODS: Subjects were imaged using a novel custom-built UHR OCT. Images were used to evaluate and describe the characteristics of anterior corneal dystrophies and degenerations. Nineteen patients underwent surgical management, and those histopathologic specimens were analyzed and correlated with the UHR OCT images. MAIN OUTCOME MEASURES: Comparison of clinical findings, UHR OCT images, and corresponding histopathologic specimens. RESULTS: The UHR OCT provided clear delineation of corneal anatomic features and pathologic corneal deposits in most cases. The characteristics and depth of these deposits are illustrated and can be localized to specific layers of the cornea. When available, there was significant correlation between UHR OCT images and histopathologic features, providing a noninvasive confirmation of the clinical diagnosis. CONCLUSIONS: Ultra high-resolution OCT is an innovative technique to perform in vivo optical biopsies and a promising research and clinical tool for the evaluation of corneal pathologic features in a noninvasive manner. The future use of this novel technology will evolve and increasingly is becoming a vital tool in the clinical and surgical management of corneal diseases.

Epithelial ingrowth after Descemet stripping automated endothelial keratoplasty: description of cases and assessment with anterior segment optical coherence tomography.

PURPOSE: To describe 5 cases of epithelial ingrowth after Descemet stripping automated endothelial keratoplasty (DSAEK) and the use of anterior segment optical coherence tomography (AS-OCT) to describe the areas of ingrowth. METHODS: Five cases with epithelial ingrowth after DSAEK were examined with commercially available AS-OCT and/or a novel custom-built ultrahigh resolution (UHR) AS-OCT. Argon laser photocoagulation was also used to confirm epithelial ingrowth on the iris surface. Pathological evidence of epithelial ingrowth was noted in an eye that underwent corneoscleral grafting for extensive ingrowth through a fistulous tract. RESULTS: Epithelial ingrowth was solely in the graft-host interface in 1 case and in both the interface and retrocorneal and iris surfaces in 4 cases. Argon laser photocoagulation on the iris confirmed epithelial ingrowth in 4 cases. The areas of epithelial ingrowth were imaged in 1 case with the Visante AS-OCT and in 3 cases with an UHR-OCT. In 1 case, block excision with corneoscleral grafting was required. CONCLUSIONS: Epithelial ingrowth can occur after DSAEK. This series reports 5 cases of epithelial ingrowth into the interface and/or the retrocorneal surface after DSAEK. Imaging with AS-OCT, specifically the UHR-OCT, and argon laser photocoagulation can help confirm the diagnosis. UHR-OCT imaging of the interface and retrocorneal surfaces can provide clues to the origin of epithelial ingrowth. Four cases were observed. One case underwent corneoscleral grafting with histological confirmation of epithelial ingrowth.

Long-term results of femtosecond laser-assisted sutureless anterior lamellar keratoplasty.

PURPOSE: To evaluate the long-term results of femtosecond laser-assisted anterior lamellar keratoplasty (FALK) for anterior corneal pathologies. DESIGN: Retrospective, noncomparative, interventional case series. PARTICIPANTS: Thirteen consecutive patients who underwent FALK for anterior corneal pathologies. INTERVENTION: Femtosecond laser-assisted sutureless anterior lamellar keratoplasty. MAIN OUTCOME MEASURES: Best spectacle-corrected visual acuity (BSCVA), manifest refraction, need for adjunctive surgery, and complications. RESULTS: Follow-up ranged from 12 to 69 months (mean = 31 months). The BSCVA was significantly improved over preoperative values at the 12-, 18-, 24-, and 36-month visits. A BSCVA greater than 20/30 was achieved in 54% of patients at the 12-month visit when all 13 patients were available for follow-up, in 50% and 33% of patients at the 18- and 24-month visits, respectively, when 12 patients were available, and in 60% and 50% of patients at the 36- and 48-month visits when 5 and 2 patients were available, respectively. The BSCVA of the eye that completed the 60- and 70-month visits was 20/50. Patients achieved a mean gain of 5 lines of BSCVA at the 6-, 12-, 18-, and 24-month visits, 4 lines at the 36-month visit, 5 lines at the 48-month visit, and 6 lines at the 60- and 72-month visits. Two patients lost a mean of 1.5 lines of BSCVA because surface haze developed after photorefractive keratectomy (PRK) and granular dystrophy recurred in the graft. At a mean of 5 weeks postoperatively, 83.3% of patients achieved BSCVA within 2 lines of that recorded at the 24-month visit. At the 12-month visit, mean spherical equivalent and refractive astigmatism were -0.4 diopters (D) and 2.2 D, respectively, with no significant shift from preoperative values or values recorded in different follow-up visits. Adjunctive surgeries included phototherapeutic keratectomy, PRK, cataract extraction, and epithelial ingrowth debridement. Complications included residual corneal pathology, mild interface haze, anisometropia, recurrence of pathology, haze after adjunctive PRK, dry eye, epithelial ingrowth, and suspicious ectasia. CONCLUSIONS: Femtosecond laser-assisted sutureless anterior lamellar keratoplasty improves the BSCVA of patients with anterior corneal pathologies with rapid visual rehabilitation and no significant induced astigmatism. Our preliminary results indicate that FALK results remained stable throughout the follow-up period.

Reduced tear meniscus dynamics in dry eye patients with aqueous tear deficiency.

PURPOSE: To measure the tear meniscus dynamics in aqueous tear deficiency dry eye patients using optical coherence tomography. DESIGN: Clinical research study of a laboratory technique. METHODS: Twenty-five aqueous tear deficiency dry eye patients and 30 healthy subjects were recruited. Upper and lower tear menisci of 1 randomly selected eye of each participant were imaged during normal and delayed blinking using optical coherence tomography. Measured parameters included upper tear meniscus height and volume, lower tear meniscus height and volume, the blink outcome defined as the meniscus volume change during blink action, and open eye outcome defined as the meniscus volume change during the open eye period. RESULTS: During normal blinking, both tear meniscus height and volume before blink in dry eye patients were significantly smaller than those in healthy subjects, except for the upper tear meniscus volume. During normal blinking, the blink outcome and open eye outcome of lower tear meniscus were significantly smaller in dry eye patients compared with healthy subjects. During delayed blinking, the upper and lower tear menisci heights and volumes significantly increased in both groups. However, dry eye patients had smaller increases than healthy subjects. During delayed blinking, the open eye outcomes of upper and lower tear menisci were smaller in dry eye patients than healthy subjects. CONCLUSIONS: Dry eye patients seem to have reduced tear meniscus dynamics during normal blinking and smaller increases of meniscus volume during delayed blinking. Analysis of tear meniscus dynamics may provide more insight in the altered tear system in dry eye patients.

Use of ultra-high-resolution optical coherence tomography to detect in vivo characteristics of Descemet's membrane in Fuchs' dystrophy.

PURPOSE: To demonstrate the capability of ultra-high-resolution (UHR) anterior segment optical coherence tomography (OCT) to image Descemet's membrane (DM) and measure its thickness in vivo. (2) To evaluate the use of DM characteristics and thickness in the diagnosis of Fuchs' dystrophy. DESIGN: Case-control study. PARTICIPANTS: Twenty eyes of 12 Fuchs' dystrophy patients, 20 eyes of 13 young normal, and 20 eyes of 15 elderly normal subjects. METHODS: Subjects were imaged using novel, custom-built UHR-OCT. Images were used to describe the characteristics of DM. Custom-made software was used to measure DM thickness and central corneal thickness (CCT). Specimens of DM obtained from Fuchs' dystrophy patients who underwent endothelial keratoplasty (EK) were histopathologically examined. Regression analyses were used to assess the correlation of DM thickness measured by UHR-OCT in vivo and by light microscopy and to determine the intergroup correlations between age, CCT, and DM thickness. MAIN OUTCOME MEASURES: We assessed DM characteristics and thickness, CCT, and age. RESULTS: Using UHR-OCT, the DM seemed in normal young subjects as a single, opaque, smooth line and in normal elderly subjects as a band of 2 smooth opaque lines with a translucent space in between. In Fuchs' dystrophy, DM appeared as a thickened band of 2 opaque lines; the anterior line was smooth whereas the posterior line had a wavy and irregular appearance with areas of localized thickenings. The DM thickness measured in vivo by UHR-OCT correlated significantly with that measured by light microscopy in 5 Fuchs' dystrophy eyes that underwent EK. The average central thicknesses of DM in normal young, in normal elderly and in Fuchs' dystrophy eyes were 10+/-3, 16+/-2, and 34+/-11 microm, respectively (P<0.001). There was a significant correlation between age and DM thickness only in normal groups. In Fuchs' dystrophy patients, there was a significant correlation between CCT and DM thickness that was not significant for normal groups. CONCLUSIONS: Ultra-high-resolution OCT is an innovative technique for the in vivo imaging of DM. Determining DM characteristics and thickness by UHR-OCT could be a new approach for the diagnosis of Fuchs' dystrophy.

Cataract surgery after pars plana vitrectomy.

PURPOSE OF REVIEW: To review recent studies and advances and their possible implications in the care of patients undergoing cataract surgery after pars plana vitrectomy. RECENT FINDINGS: Optical biometry has shown to be superior to ultrasound biometry in vitrectomized eyes but still not achieving as good results as it does in nonvitrectomized eyes. Blue light-filter intraocular lenses, with their possible advantage of macular protection, have shown no operative or functional disadvantages in vitrectomized eyes, and thus their routine use can be justified. However, presbyopia-correcting intraocular lenses, at least at their current stage of development, generally, are still not accepted for vitrectomized eyes. Combining cataract surgery with intravitreal injections of bevacizumab or triamcinolone acetonide in patients with macular edema and cataract is advisable to avoid exacerbation of the condition and improve visual outcome. Despite the recent advances, incidences of posterior capsular opacification and retinal detachment are still considerable. SUMMARY: Understanding ocular anatomical alterations imposed by the previous pars plana vitrectomy surgery and the underlying vitreoretinal disease will allow the surgeon to address the special challenges. Despite that, recent advances in techniques and instrumentation have improved the surgical safety and outcomes, reported complications rates are still relatively high.

In situ visualization of tears on contact lens using ultra high resolution optical coherence tomography.

OBJECTIVE: To demonstrate the capability of directly visualizing the tear film on contact lenses using optical coherence tomography (OCT). METHODS: Six eyes of three healthy subjects wearing PureVision and ACUVUE Advance soft and Boston RGP hard contact lenses were imaged with a custom built, high speed, ultra-high resolution spectral domain optical coherence tomograph. Refresh Liquigel was used to demonstrate the effect of artificial tears on the tear film. RESULTS: Ultra high resolution images of the pre- and post-lens films were directly visualized when each lens was inserted onto the eye. After the instillation of artificial tears during lens wear, the tear film was thicker. The post-lens tear film underneath the lens edge was clearly shown. Interactions between the lens edges and the ocular surface were obtained for each of the lens types and base curves. With a contrast enhancement agent, tear menisci on the contact lenses around the upper and lower eyelids were highlighted. With hard contact lenses, the tear film was visualized clearly and changed after a blink when the lens was pulled up by the lid. CONCLUSIONS: Ultra-high resolution OCT is a potentially promising technique for imaging tears around contact lenses. This successful demonstration of in situ post-lens tear film imaging suggests that OCT could open a new era in studying tear dynamics during contact lens wear. The novel method may lead to new ways of evaluating contact lens fitting.