Identification of A Novel TGFBI Gene Mutation (p.Serine524Cystine) Associated with Late Onset Recurrent Epithelial Erosions and Bowman Layer Opacities

BACKGROUND

Most transforming growth factor beta-induced (TGFBI) corneal dystrophies are associated with a characteristic phenotype, clinical course, and a conserved mutation in the TGFBI gene. However, we report a novel TGFBI missense mutation associated with a late-onset, variant Bowman layer dystrophy.

METHODS

Participants underwent slit-lamp examination and multimodal imaging. Polymerase chain reaction amplification and Sanger sequencing were performed on saliva-derived genomic DNA to screen TGFBI exons 4 and 12 as well as COL17A1 exon 46. PolyPhen-2 and SIFT were used to predict the functional impact of any identified variants.

RESULTS

A 56-year-old Thai woman reported a four-year history of decreased vision and intermittent eye irritation, suggestive of recurrent epithelial erosions, in both eyes. Slit-lamp exam revealed bilateral, irregular, limbal-sparing Bowman layer opacities, which were also noted on anterior segment optical coherence tomography. Phototherapeutic keratectomy was performed in the right eye, improving the best-corrected visual acuity from 20/50 to 20/30. Sequencing of the TGFBI gene revealed a novel heterozygous, missense mutation in exon 12 (c.1571 C > G; p.Ser524Cys), which was present in an affected son and absent in an unaffected son, and was predicted to be damaging by PolyPhen-2 and SIFT. The patient was diagnosed with a variant Bowman layer dystrophy given the late onset of an atypical phenotype and the identification of a novel TGFBI mutation.

CONCLUSIONS

A novel TGFBI missense mutation is associated with a late-onset Bowman layer dystrophy. Given the atypical clinical appearance and course, molecular genetic analysis was utilized to establish a definitive diagnosis.

Large Field of View Corneal Epithelium and Bowman's Layer Thickness Maps in Keratoconic and Healthy Eyes

PURPOSE

To assess differences between epithelium thickness (ET) and Bowman's layer thickness (BLT) maps in keratoconic eyes and healthy eyes.

DESIGN

Cross-sectional study.

METHODS

Setting: institutional.

STUDY POPULATION

47 patients (1 eye) with keratoconus (KC) and 20 healthy subjects (1 eye).

OBSERVATION PROCEDURE

epithelium and Bowman's layer measurements were performed by using custom-designed polarization-sensitive optical coherence tomography (PS-OCT) with a conical scanning optics design. En face corneal ET and BLT maps with a diameter of 11 mm were computed. Main outcome measurements were mean ET and BLT of 25 sectors; the thinnest (minET, minBLT) and thickest sectors (maxET, maxBLT) were assessed. Ratios between thinnest/thickest sectors (R1) and between mean ET and BLT of the inferior temporal quadrant/superior nasal quadrant (R2) were calculated (R1ET, R1BLT; R2ET, R2BLT). Receiver operator characteristic (ROC) curve analysis was used to assess the diagnostic power of statistically different parameters.

RESULTS

In healthy eyes, smooth ET maps were observed. KC eyes showed a "doughnut pattern." The BLT maps of healthy eyes had a smooth appearance, but highly irregular "moth"-like damage pattern could be observed in keratoconic eyes. Highest area under the curve values were found for the thinnest sector of the BLT map, the R1ET, and the thinnest sector of the ET map.

CONCLUSIONS

PS-OCT imaging enables the visualization of significant differences of the corneal epithelium and the Bowman's layer in en face maps covering almost the entire cornea. ET and BLT profiles could clearly show their diagnostic importance for the distinguishing of keratoconic eyes and healthy eyes.

Bowman's topography for improved detection of early ectasia

The aim of this study was to evaluate whether OCT topography of the Bowman's layer and artificial intelligence (AI) can result in better diagnosis of forme fruste (FFKC) and clinical keratoconus (KC). Normal (n = 221), FFKC (n = 72) and KC (n = 116) corneas were included. Some of the FFKC and KC patients had the fellow eye (VAE-NT) with normal topography (n = 30). The Scheimpflug and OCT scans of the cornea were analyzed. The curvature and surface aberrations (ray tracing) of the anterior corneal surface [air-epithelium (A-E) interface in OCT] and epithelium-Bowman's layer (E-B) interface (in OCT only) were calculated. Four random forest models were constructed: (1) Scheimpflug only; (2) OCT A-E only; (3) OCT E-B only; (4) OCT A-E and E-B combined. For normal eyes, both Scheimpflug and OCT (A-E and E-B combined) performed equally in identifying these eyes (P = .23). However, OCT A-E and E-B showed that most VAE-NT eyes were topographically similar to normal eyes and did not warrant a separate classification based on topography alone. For identifying FFKC eyes, OCT A-E and E-B combined performed significantly better than Scheimpflug (P = .006). For KC eyes, both Scheimpflug and OCT performed equally (P = 1.0). Thus, OCT Topography of Bowman's layer significantly improved the detection of FFKC eyes.

Microdistortions in Bowman's Layer 3 Years After SMILE for Myopia

PURPOSE

To investigate the characteristics and changes in microdistortions in Bowman's layer 3 years after small incision lenticule extraction (SMILE).

METHODS

In this non-randomized, prospective study, 50 eyes of 28 patients who received SMILE with a mean spherical equivalent of -6.72 ± 1.41 diopters (D) were divided into a thin lenticule group (lenticule thickness ⩽ 135 µm) and a thick lenticule group (lenticule thickness > 135 µm). Examinations were performed preoperatively and 1 day, 1 month, and 3 years after SMILE. Microdistortions in Bowman's layer determined via optical coherence tomography were analyzed digitally.

RESULTS

All patients completed the follow-up with no complications. Three years after SMILE, no eyes exhibited loss of corrected distance visual acuity. The safety index was 1.20 ± 0.15 and the efficacy index was 1.01 ± 0.10. The respective mean lengths of microdistortions at 1 day, 1 month, and 3 years after SMILE were 2,397.47 ± 1,777.22, 3,444.87 ± 2,145.82, and 1,283.81 ± 1,184.43 μm. The respective mean microdistortion lengths at each time-point were 1,781.29 ± 17,78.15, 2,617.78 ± 1,949.67, and 1,112.95 ± 1,245.88 μm in the thin lenticule group and 2,692.10 ± 1,825.20, 3,739.20 ± 2,072.60, and 1,332.44 ± 1,137.33 μm in the thick lenticule group.

CONCLUSIONS

Microdistortions in Bowman's layer can remain 3 years after SMILE, but their lengths decrease over time. Thicker lenticules were associated with the early occurrence of microdistortions, but this effect decreased in the long term. [J Refract Surg. 2019;35(2):96-101.].

Epithelial Recurrent Erosion Dystrophy Secondary to COL17A1 c.3156C>T Mutation in a Non-white Family

PURPOSE

To report the identification of the collagen, type XVII, alpha 1 (COL17A1) c.3156C>T mutation associated with epithelial recurrent erosion dystrophy (ERED) in a Thai family.

METHODS

Slit-lamp examination was performed to determine the affected status of each member of a Thai family, with multiple members demonstrating scattered Bowman layer opacities. After genomic deoxyribonucleic acid (DNA) was isolated from saliva, polymerase chain reaction (PCR) amplification and Sanger sequencing were performed to screen COL17A1 and exons 4 and 12 of the transforming growth factor β-induced gene.

RESULTS

The 67-year-old proband and her 4 siblings were examined by slit-lamp biomicroscopy, which identified bilateral subepithelial opacities in the proband and in one of the 4 siblings. In both the proband and the affected sister, screening of the COL17A1 gene identified a heterozygous c.3156C>T synonymous mutation that has been previously demonstrated to introduce a cryptic splice donor site, likely leading to aberrant splicing of COL17A1. This mutation was not identified in the unaffected siblings, and no mutations were identified in exons 4 and 12 of the transforming growth factor β-induced gene in any of the screened family members.

CONCLUSIONS

ERED associated with a COL17A1 mutation has been previously reported in only 6 families, all white. Identification of the c.3156C>T mutation, previously identified in 5 of these 6 families, in the Thai family we report indicates conservation of the genetic basis of ERED across different races and underscores the importance of ophthalmologists around the globe being familiar with ERED, which has only recently become a recognized corneal dystrophy.

Short-term Observation of Intraocular Scattering and Bowman's Layer Microdistortions After SMILE-CCL

PURPOSE

To investigate changes in intraocular scattering and Bowman's layer microdistortions after femtosecond laser small incision lenticule extraction using the continuous curvilinear lenticulerhexis technique (SMILE-CCL).

METHODS

In this prospective study, 93 eyes of 93 patients (44 women, 49 men) were treated with SMILE-CCL. Mean age was 26.09 ± 4.39 years and mean spherical equivalent was -6.31 ± 2.16 diopters. The Objective Scatter Index (OSI) was examined with an objective optical quality analysis system. Bowman's layer microdistortions in the central 4-mm optical zone were measured using Fourier-domain optical coherence tomography.

RESULTS

The mean OSI value increased from 0.67 preoperatively to 1.09 at 20 days, and then decreased to 0.84 at 3 months (P < .05). Microdistortions were observed in 62.37% of the eyes at 20 days and 48.39% at 3 months postoperatively (P < .05). The width of the microdistortions per meridian was 283.18 ± 197.19 μm at 20 days; this decreased to 156.00 ± 159.86 μm at 3 months (P < 0.05). Regression analysis models revealed that older age (b = 0.02, P = .03) and higher preoperative spherical equivalent (b = -0.09, P < .05) resulted in higher postoperative OSI values; no significant association was found between postoperative OSI values and microdistortion-related parameters (P > .05). Higher preoperative spherical equivalent (b = -0.28, P = .01) and thinner preoperative corneal thickness (b = -0.02, P = .01) were associated with more microdistortions.

CONCLUSIONS

SMILE induced a temporary increase in OSI values and Bowman's layer microdistortions. The microdistortions did not influence intraocular scattering. [J Refract Surg. 2018;34(6):387-392.].

Noncontact Quantification of Topography of Anterior Corneal Surface and Bowman's Layer With High-Speed OCT

PURPOSE

To quantify keratometry and wavefront aberration of the anterior corneal surface and epithelium-Bowman's layer interface using anterior segment optical coherence tomography (OCT).

METHODS

Twenty-five normal eyes and 25 eyes with keratoconus were retrospectively analyzed. The anterior corneal edge and epithelium-Bowman's layer interface were segmented from 12 distortion-corrected OCT B-scans. Axial tangential curvatures and wavefront aberration were calculated by ray tracing and 6th order Zernike analyses. All eyes underwent simultaneous imaging with Pentacam (Oculus Optikgeräte GmbH, Wetzlar, Germany). The Pentacam elevation data were used for aberration analyses using the same ray-tracing method. The paired t test was used to compare the variables.

RESULTS

In normal eyes, mean steep axis and maximum keratometry of OCT of the anterior corneal surface and epithelium-Bowman's layer interface were significantly greater than the same of the Pentacam anterior corneal surface (P < .05). Mean root mean square of higher order aberrations of the OCT surfaces was greater than the same of the Pentacam surface by a factor of 4. In eyes with keratoconus, mean steep axis and maximum keratometry of the OCT epithelium-Bowman's layer interface was the greatest (P < .05). Mean root mean square of the higher order aberrations and vertical coma of the OCT epithelium-Bowman's layer interface was the greatest (P < .05). In general, the aberrations of the OCT epithelium-Bowman's layer interface were significantly greater than those of the Pentacam anterior corneal surface.

CONCLUSIONS

A noncontact method to quantify the topography and aberrations of corneal surfaces with OCT was presented. OCT measurements yielded greater curvature and aberrations than Pentacam in both normal and keratoconic eyes. [J Refract Surg. 2017;33(5):330-336.].

The Impact of Flap Creation Methods for Sub-Bowman's Keratomileusis (SBK) on the Central Thickness of Bowman's Layer

Purpose

To determine the impact of flap creation methods for sub-Bowman’s keratomileusis (SBK) on central Bowman’s layer thickness.

Methods

SBK flaps were made by Moria microkeratome for 20 subjects and by femtosecond (FEMTO) laser for 21 subjects. Corneal sublayer thicknesses were measured by ultra-high resolution optical coherence tomography before SBK and at 1 day, 1 week, 2 weeks, and 1 month afterwards. Each subject was imaged twice on each visit. Thicknesses of central epithelium, Bowman’s layer, flap, and total cornea were calculated using a custom-made automated image processing algorithm. The repeatability of sublayer thickness measurements was tested by the intraclass correlation coefficient (ICC) and by the coefficient of repeatability (CoR) at 1 week post-SBK.

Results

ICCs of the Moria and FEMTO groups were ≥0.959 and ≥0.961 respectively for all sublayer measurements. The segmentation CoRs were less than 6.78% and 5.63% respectively. For both groups, microdistortions were present in the epithelium and Bowman’s layer after SKB. The flap thickness of the Moria group was 9.8 μm (95% confidence interval: 4.8 – 14.8μm) thinner than the FEMTO group one day after SBK (independent samples t-test, P < 0.05). Bowman’s layer became thicker by 1.6 ± 1.1 μm and 1.7 ± 1.6 μm one day post-SBK for the Moria and FEMTO groups (repeated ANOVA, P < 0.05) and then remained stable. Corneal and sublayer thickness were similar between the two groups.

Conclusions

Central Bowman’s layer thickness increased 1 day post-SBK. Flap creation by Moria microkeratome and femtosecond laser did not have significantly different impacts on Bowman’s layer thickness following SBK.

Trial Registration

Chinese Clinical Trial Registry (ChiCTR) NO: ChiCTR-OCH-14004525

Phenotype and genotype analysis in patients with macular corneal dystrophy

AIM

The aim of this study was to analyse corneal morphological organisation and identify mutations in the carbohydrate sulfotransferase 6 gene (CHST6) in patients with macular corneal dystrophy originating in a Polish population.

METHODS

Macular corneal dystrophy was diagnosed in 24 patients based on the slit-lamp exam, confocal microscopy, 1310 nm time domain and 840 nm spectral domain optical coherence tomography. 10 corneal buttons obtained from penetrating keratoplasty were processed for light microscopy. Genetic analysis of the CHST6 gene was performed, followed by a study of the sequencing results.

RESULTS

Highly reflective, diffuse corneal deposits and a general increase in reflectivity were revealed with optical coherence tomography and confocal microscopy. The deposits extended from the Bowman layer to the Descemet membrane and correlated with the Alcian blue-positive granular-filamentous material into and around the stromal keratocytes confirmed by structural analysis of the corneal buttons. The genetic analysis of the blood samples identified the following mutations and single nucleotide polymorphisms: novel P64L (heterozygous), Y110C (homozygous), R162G and L200R, and M1L (heterozygous and homozygous).

CONCLUSIONS

Genetic mutation heterogeneity was revealed. No phenotype heterogeneity was revealed among patients with in vivo corneal morphology assessment or histological analysis.

Role of biochemical factors in the pathogenesis of keratoconus

Keratoconus (KC) is a corneal disease associated with structural abnormalities in the corneal epithelium, Bowman's layer and stroma and altered concentration of tear components. KC corneas show a different pattern of collagen lamellae than their normal counterparts. Also, a reduction of several collagen types in KC epithelium and stroma was observed. Altered expression and/or activity of lysyl oxidase, a critical enzyme of the biogenesis of connective tissue detected in KC corneas, may weaken covalent bonds between collagen and elastin fibrils, what may lead to biomechanical deterioration of the cornea. Increased activity of matrix metalloproteinases observed in KC may induce the degradation of the extracellular matrix causing damage to the cornea. Oxidative and nitrative stress play an important role in KC pathogenesis and KC corneas are characterized by the disturbed lipid peroxidation and nitric oxide pathways. Malfunctioning of these pathways may lead to accumulation of their toxic by-products inducing several detrimental effects, along with apoptosis of the corneal cells, which may result from the loss of β-actin or increased levels of cytokines, including interleukin-1 and -6. Change in the expression of genes associated with wound healing, including the nerve growth factor and the visual system homeobox 1, may contribute to increased susceptibility of KC corneas to injury. Consequently, biochemical changes may play an important role in KC pathophysiology and, therefore, can be considered in prevention, diagnosis, prognosis and in the therapy of this disease as well.

Demographic patterns and treatment outcomes of patients with recurrent corneal erosions related to trauma and epithelial and bowman layer disorders

PURPOSE

To evaluate demographics and outcomes of patients with recurrent corneal erosions related to trauma and epithelial and Bowman layer disorders.

DESIGN

Retrospective case series.

METHODS

setting: Wills Eye Institute, Philadelphia, Pennsylvania. study population: Two hundred seventy-two eyes (230 patients) presenting between 2008 and 2011 with recurrent corneal erosions related to trauma and epithelial and Bowman layer disorders. procedure: Conservative management, diamond burr polishing, excimer laser phototherapeutic keratectomy (PTK), and epithelial debridement alone. main outcome measure: Recurrence of erosions, more than 6 weeks after commencing treatment.

RESULTS

Mean age was 46.5 ± 14.6 (2-85) years. Female subjects accounted for 53% of patients and 18.3% had bilateral involvement. Etiology included epithelial basement membrane dystrophy in 52.9% (144/272) and trauma in 25.7% (70/272). One hundred sixty-six eyes with more than a single visit were initially managed conservatively, 68 of 166 (40.9%) had diamond burr polishing, 7 of 166 (4.2%) had PTK, and 4 of 166 (2.4%) had epithelial debridement alone. Many eyes had >6 weeks follow-up: 120 of 166 (72.3%) after conservative management, 54 of 68 (79.4%) after diamond burr polishing, 7 of 7 (100%) after PTK, and 4 of 4 (100%) after epithelial debridement. Percentage of eyes with recurrence was 56.7% (68/120) after conservative management, 14.8% (8/54) after diamond burr polishing, and 28.6% (2/7) after PTK. Rate of recurrence (eye-years) was 0.74, 0.19, and 0.23 with conservative management, diamond burr polishing, and PTK, respectively. Mild haze was seen in 22.2% of eyes (12 eyes) after diamond burr polishing and 28.6% (2 eyes) after PTK.

CONCLUSION

Recurrent corneal erosions are most commonly associated with epithelial basement membrane dystrophy. Patients are generally initially managed conservatively, with recurrence in more than half of eyes. Diamond burr polishing is the most common surgical intervention and is effective in a majority of eyes.

Anterior segment optical coherence tomography-guided big-bubble technique

PURPOSE

To evaluate the feasibility of intraoperative anterior segment (AS) optical coherence tomography (OCT) for quantification of the corneal depth reached with the dissecting cannula used for deep anterior lamellar keratoplasty, as well as its correlation with the success rate of big-bubble formation.

DESIGN

Retrospective, noncomparative, interventional case series.

PARTICIPANTS

One hundred consecutive keratoconus patients.

INTERVENTION

Deep anterior lamellar keratoplasty was performed using the big-bubble technique. During surgery, the cannula used for pneumatic dissection was inserted into the peripheral stroma and advanced as deep and far toward the center as believed adequate by the surgeon. Then, after retracting the cannula, AS OCT was performed. The cannula was placed back in position and creation of the big bubble was attempted.

MAIN OUTCOME MEASURES

Stromal depth reached with the cannula tip, success rate in achieving big-bubble formation, and complication rate.

RESULTS

Bubble formation was obtained in 70 of 100 eyes (70%). In all remaining eyes, the procedure was completed by manual deep lamellar dissection. The average depth reached by the cannula tip was 104.3±34.1 μm from the internal corneal surface; the mean value recorded in cases of successful big-bubble formation (90.4±27.7 μm) was statistically lower than that measured in failed procedures (136.7±24.2 μm). In 1 case, corneal perforation occurred during the insertion of the cannula and required conversion to penetrating keratoplasty (PK). In 8 eyes, small microperforations occurred during stromal excision but could be managed conservatively, avoiding conversion to PK. In 2 advanced cones, an incomplete bubble formation was obtained, necessitating manual peripheral stromal removal.

CONCLUSIONS

Successful big-bubble formation can be anticipated if pneumatic dissection is attempted at a sufficiently deep level. Although an ideal depth could not be defined, AS OCT allows objective evaluation of the depth reached by the cannula tip used for pneumatic dissection. The AS OCT findings may confirm the decision to proceed with air injection. It is possible that cannula repositioning based on the AS OCT depth may improve the success rate for big-bubble formation.

Epithelium and Bowman's layer thickness and light scatter in keratoconic cornea evaluated using ultrahigh resolution optical coherence tomography

A custom-developed ultrahigh resolution optical coherence tomography with an axial resolution of 1.1 μm in corneal tissue was used to characterize thickness and light scatter of the epithelium and Bowman's layer in keratoconic (KC) cornea noninvasively. A 4-mm wide vertical corneal section around the apex in nine KC and eight normal eyes was imaged in vivo. The epithelium and Bowman's layer were visualized and their thickness profiles were quantified. Scatter was quantified based on the sensitivity normalized mean signal intensity distribution. Average mean thickness of the epithelium and Bowman's layer in KC eyes was significantly smaller (p<0.05) than the normal eyes. The epithelium thickness variation across a central 3-mm cornea was significantly larger in KC eyes than in normal eyes. The scatter in KC eyes was significantly increased only for Bowman's layer. The changes observed in this study could improve our understanding of the underlying disease mechanism of KC and can provide new indications for early disease diagnosis.

Immunohistochemical expression of Fas ligand (FasL) and neprilysin (neutral endopeptidase/CD10) in keratoconus

Recent evidence demonstrated a correlation between apoptosis and neprilysin expression. The aim of this study was to investigate the immunohistochemical expression of Fas ligand (FasL) and neprilysin in keratoconic corneas in comparison to normal cadaver corneas to evaluate if such molecules play a role in the pathogenesis of keratoconus. We studied the expression of FasL and neprilysin in corneal specimens removed during penetrating keratoplasty in 15 cases with keratoconus and compared them with 5 normal cadaver corneas. In keratoconus, FasL was expressed in epithelium, endothelium and sub-Bowman's stroma only, while neprilysin was expressed in epithelium, endothelium and all stromal layers. All normal corneas showed weak expression of both markers in basal epithelial layer only. In keratoconus, corneal epithelium with higher expression of FasL may evoke apoptosis in keratocytes, while neprilysin could prevent possible rescue of keratocytes from apoptosis.

In vivo morphologic characteristics of Salzmann nodular degeneration with ultra-high-resolution optical coherence tomography

PURPOSE

To examine the in vivo morphologic properties of Salzmann nodular degeneration with ultra-high-resolution optical coherence tomography (OCT).

DESIGN

Interventional case series.

METHODS

SETTING

Single-center academic practice.

STUDY POPULATION

Nineteen eyes of 12 patients with Salzmann nodular degeneration were recruited to participate in the study.

OBSERVATIONAL PROCEDURE

Subjects were imaged using novel, custom-built ultra-high-resolution OCT. Images were used to describe in vivo characteristics of subepithelial nodules. Morphometric measurements were made with custom-built software. Ultra-high-resolution OCT findings were compared with histopathologic findings in 3 patients.

MAIN OUTCOME MEASURES

Identifiable in vivo morphologic characteristics of Salzmann nodular degeneration with ultra-high-resolution OCT.

RESULTS

Ultra-high-resolution OCT images demonstrate intraepithelial fibrous nodules with epithelial thinning and corneal surface elevation. The Bowman layer could be differentiated in 9 of 12 patients. The difference between the mean thickness of epithelium above the nodule and the thickness of normal epithelium was statistically significant (P < .0001). The correlation between thickness of the epithelium and thickness of the nodule was statistically significant (r = -0.48; P < .0001). The correlation between thickness of the nodule and total surface thickness (thickness of the epithelium + thickness of the nodule) was statistically significant (r = 0.98; P < .0001). Ultra-high-resolution OCT findings were consistent with histopathologic results.

CONCLUSIONS

Ultra-high-resolution OCT can be used to noninvasively image the cornea in Salzmann nodular degeneration. This new imaging technique helps us to demonstrate different in vivo morphologic characteristics of Salzmann nodular degeneration.

Real-time optical coherence tomography-guided femtosecond laser sub-Bowman keratomileusis on human donor eyes

PURPOSE

To determine the usefulness of optical coherence tomography (OCT) as a tool in guiding the femtosecond (fs) laser in the creation of a sub-Bowman keratomileusis (SBK) flap in human eyes.

DESIGN

A nonrandomized case series.

METHODS

In a private research laboratory setting, we performed an in vitro investigation on human autopsy eyes. Five human cadaver eyes, unsuitable for transplantation, underwent flap creation with a fs laser. The laser procedure was controlled in real-time with an OCT system (Thorlabs HL AG, Luebeck, Germany) to ensure that the cut was placed just underneath the Bowman layer. The fs laser worked at a repetition rate of 10 MHz with a single-pulse duration of < 400 fs (pulse energy in the nanoJoule range). As a control, all eyes underwent histologic dissection (toluidine blue) and were examined using light microscopy (LM).

RESULTS

Video monitoring of the flap creation supported the feasibility of real-time OCT monitoring of the fs laser flap creation process. A clear distinction of the corneal epithelium was possible in all eyes. The Bowman membrane was not identified in all donor eyes at the given resolution of the OCT used in this study. Still, LM examination confirmed that the real-time monitoring assured a positioning of the cutting plane at minimum distance underneath the Bowman layer.

CONCLUSION

This small laboratory test offers evidence that real-time OCT monitoring of creation of a SBK flap using a fs laser is possible, thus ensuring that the flap is created at the proper depth.

Corneal wound healing from the perspective of keratoplasty specimens with special reference to the function of the Bowman layer and Descemet membrane

PURPOSE

To review corneal wound healing with special reference to the function of the Bowman layer and Descemet membrane.

METHODS

Corneal specimens were obtained from keratoplasties, including regrafted cases. Recipient corneal buttons were evaluated histopathologically with attention to 5 layers of corneal structure: 3 cellular layers consisting of epithelial cells, keratocytes, and endothelial cells and 2 acellular layers consisting of the Bowman layer and Descemet membrane.

RESULTS

Subepithelial fibrosis was found in advanced bullous keratopathy. The possible source of subepithelial fibrosis was either conjunctival stroma or corneal stroma through disruption of the Bowman layer. Subepithelial fibrosis was observed in the area of the Bowman layer disruption at the host-graft junction in regrafted cases. The Bowman layer was disrupted in eyes with not only keratoconus but also corneal dystrophy such as macular dystrophy and gelatinous drop-like dystrophy. Newly formed, thin Descemet membrane was found in keratoconic eyes of patients with acute hydrops. Retrocorneal membranes were observed in eyes with advanced bullous keratopathy and graft failure. Abnormal wound healing of Descemet membrane such as override and separation was found in the host-graft interface of regrafted eyes, causing stromal overgrowth.

CONCLUSIONS

The Bowman layer and Descemet membrane seem to serve as barriers to separate 3 cellular layers of epithelium, stroma, and endothelium. Disruption of the Bowman layer forms a new epithelial-stromal interaction and may cause cellular proliferative response. Separation of Descemet membrane can provide the trigger for emanating stromal tissue from the wound edge.

Spontaneous and inheritable R555Q mutation in the TGFBI/BIGH3 gene in two unrelated families exhibiting Bowman's layer corneal dystrophy

PURPOSE

Bowman's layer corneal dystrophies (CDBs) include 2 distinct types: CDB1, or Reis-Bücklers (RBCD), and CDB2, or Thiel-Behnke (TBCD). We studied the genetic basis of 2 cases of apparent spontaneous CDB mutations and attempted to determine if these are sporadic and inheritable mutations.

DESIGN

Retrospective molecular genetic study and case report.

PARTICIPANTS

Twelve patients were recruited from 2 unrelated families for this study, including 2 affected individuals from one family (family A) and 1 affected individual from another (family B).

METHODS

Slit-lamp examination was performed for each patient to determine the disease phenotype. Histological analysis of affected cornea specimens was used for identification of pathogenic corneal opacities in 2 affected patients from family A.

MAIN OUTCOME MEASURES

Genomic DNA was isolated from the blood samples and used for mutation screening of the TGFBI/BIGH3 gene. Sixteen polymorphic DNA markers from 9 different chromosomes were used to establish the maternity and paternity of the 2 probands.

RESULTS

The 2 families were confirmed to be unrelated. The age onset of ocular symptoms was <2 years for all 3 affected patients. Clinical diagnoses of CDB1 (RBCD) and CDB2 (TBCD) were made for probands A and B, respectively. The affected corneas showed epithelial haze with diffuse, irregular, patchy opacities in a honeycomb and geographic pattern. Subepithelial plaques, increased trichome staining of anterior stroma, and irregular Bowman's layer were observed. An R555Q mutation was found in TGFBI/BIGH3 in the 2 probands but not in their parents. The son of proband A was also affected and apparently inherited his disease allele from his father.

CONCLUSION

The R555Q mutation occurred spontaneously and independently in the 2 unrelated CDB families and was confirmed to be transmitted to the next generation in 1 of the 2 families. These findings strongly support the notion that a genetic diagnosis should be determined for CDB and other dystrophies associated with mutations in TGFBI/BIGH3. The discovery of a spontaneous mutation should alert clinicians to be aware of the existence of genetic alterations for their patients without apparent family history of the disease.

In Vivo Laser Confocal Microscopy Findings for Bowman’s Layer Dystrophies (Thiel–Behnke and Reis–Bücklers Corneal Dystrophies)

OBJECTIVE

To investigate microstructures in patients with genetically confirmed Bowman's layer dystrophies (Thiel-Behnke or Reis-Bücklers corneal dystrophy) using an in vivo laser scanning confocal microscope.

DESIGN

Single-center, prospective, comparative small case series.

PARTICIPANTS

Two patients from one pedigree (a 29-year-old woman and 58-year-old man) with Thiel-Behnke corneal dystrophy (Arg555Gln [R555Q] heterozygous missense mutation of human transforming growth factor beta-induced [TGFBI] gene) and 3 patients from one pedigree (a 70-year-old woman, 58-year-old man, and 14-year old man) with Reis-Bücklers corneal dystrophy (Arg124Leu [R124L] heterozygous missense mutation of the TGFBI gene) were examined. Two patients with Reis-Bücklers corneal dystrophy exhibited recurrence after corneal transplantation.

TESTING

All patients were examined by slit-lamp biomicroscopy. The center and the peripheral cornea of both eyes also were examined by in vivo laser scanning confocal microscopey. Image analysis was used to identify the corneal epithelial and stromal deposits correlated with each disorder.

MAIN OUTCOME MEASURES

Selected images of the corneal layers were evaluated qualitatively for the shape and degree of light reflection of the deposits.

RESULTS

In each dystrophy, distinct characteristic deposits were observed in the epithelium and Bowman's layer, respectively, by in vivo laser scanning confocal microscopy. In Thiel-Behnke corneal dystrophy, the deposits in the epithelial basal cell layer showed homogeneous reflectivity with round edges accompanying dark shadows. In contrast, deposits in Reis-Bücklers corneal dystrophy in the same cell layer showed extremely high reflectivity from small granular materials without any shadows in all cases. In each dystrophy, Bowman's layer was replaced totally with pathological materials; the reflectivity of those materials is much higher in Reis-Bücklers corneal dystrophy than in Thiel-Behnke corneal dystrophy.

CONCLUSIONS

In vivo laser scanning confocal microscopy is capable of identifying in vivo corneal microstructural changes related to Thiel-Behnke and Reis-Bückler corneal dystrophy with a higher resolution than is available with slit-lamp biomicroscopy or in vivo white-light confocal microscopy. As a result, this device may enable differentiation of Thiel-Behnke and Reis-Bücklers corneal dystrophy in vivo. In vivo laser scanning confocal microscopy also may be a valuable tool for further research into the corneal dystrophies, especially to follow the natural course.

[Histological particularities of sclerocorneal limbus--implications in ocular pathology]

The study tried to compare the sclerocorneal limbus in human eyes and animal eyes, using the same histological technique (preserving in paraphine and stained with hematoxylin-eosine, trichromic Goldner-Szekelly and orceine method). The sclerocorneal limbus represents the passage zone between cornea and sclera, and its importance for medical practice, consists on the implications of this area in the ocular physiology. We have demonstrated in this study that the two structures are not interrupted briefly; the corneal epithelium at the limbus send in the deeper structure a ramification which represents a modality of stronger anchorage of subjacent conjunctiva. At that level it is detectable a gradual translation between corneal conjunctival tissue and scleral conjunctival tissue. The vascular and neural structures are important in this area with an important role in ocular surgery, their presence of this level permeating the cicatrisation.