Bilateral infectious keratitis after small-incision lenticule extraction

We report the clinical features and management of a patient with severe bilateral infectious keratitis developing after simultaneous bilateral small-incision lenticule extraction. A 39-year-old man was referred to our emergency department 2 days after a small-incision lenticule extraction procedure for moderate myopia. He reported decreased vision, photophobia, and pain bilaterally. Visual acuity was counting fingers in the right eye and hand motion in the left eye. Slitlamp examination showed multiple white corneal infiltrates at the corneal cap-stromal bed interface. The interface was first rinsed with povidone-iodine 10.0% and then with vancomycin (50 mg/mL). Fortified antibiotics eyedrops administration was initiated. Cultures showed Streptococcus pneumonia. Anterior segment spectral-domain optical coherence tomography scans were performed daily. Once the infection was controlled 4 days later, corticosteroids eyedrops were begun. Three months postoperatively, the patient had a corrected distance visual acuity of 20/32 in the right eye and 20/25 in the left eye.

FINANCIAL DISCLOSURE

None of the authors has a financial or proprietary interest in any material or method mentioned.

[Spontaneous choroidal hemorrhage associated with novel oral anticoagulants: A report of two cases and literature review]

New direct oral anticoagulants (DOAC) have been approved for treatment and prevention of some thromboembolic diseases: acute and chronic phase of thromboembolic disease, deep venous thrombosis prophylaxis in orthopedic surgery and prevention of stroke in patients with atrial fibrillation. These molecules are an alternative to heparins and vitamin K antagonists. Among these, rivaroxaban (Xarelto^®, Bayer Schering Pharma) is a direct factor Xa inhibitor, and dabigatran etexilate (Pradaxa^®, Boehringer Ingelheim) is a direct free thrombin inhibitor. These molecules are almost the ideal anticoagulant: oral administration, few drug and food interactions, wide therapeutic target, and especially no lab monitoring. However, their use remains associated with hemorrhagic complications such as gastrointestinal, intracranial or urinary hemorrhages. We describe two clinical cases of spontaneous choroidal hemorrhage in patients treated with direct oral anticoagulants (rivaroxaban and dabigatran etexilate) for atrial fibrillation. These cases show that an ocular hemorrhagic risk exists with these drugs. Patients treated with DOAC should have the therapeutic dose adjusted based on creatinine clearance. Special monitoring should be performed in patients with age-related macular degeneration or with hypertension even though meta-analysis shows that the risk of intraocular bleeding is reduced by 22% compared with warfarin.

[Corneal collagen cross-linking to treat infectious keratitis]

Infectious keratitis are a frequent cause of ocular morbidity. Today, new treatments are necessary to combat the emergence of antibiotic resistant germs. Corneal collagen cross-linking has been suggested to treat corneal infectious (PACK-CXL). Its action would be both antimicrobial and protective for the cornea, increasing its biochemical resistence to proteolytic enzymes. In vivo, PACK-CXL might demonstrate good efficacy against bacterial keratitis, contrary to herpetic keratitis for which it is contraindicated. For fungal or amoebic keratitis, results are uncertain regarding its safety and efficacy. The purpose of this paper is to clarify the use of corneal collagen cross-linking to treat infectious keratitis.

Unilateral corneal ectasia after small-incision lenticule extraction in a 43-year-old patient

Unilateral corneal ectasia developed after small-incision lenticule extraction for mild myopia in a 43-year-old man with preoperative asymmetric astigmatism. The ectasia was diagnosed 4 years postoperatively. Preoperative data showed asymmetric astigmatism with no signs of forme fruste keratoconus. Inferior anterior curvature steepening exceeded 2.00 diopters without bulging of the posterior curvature, and pachymetric thickness exceeded 515 μm. Corneal ectasia can occur after small-incision lenticule extraction in patients older than 40 years with preoperative asymmetric astigmatism.

Highly concentrated collagen solutions leading to transparent scaffolds of controlled three-dimensional organizations for corneal epithelial cell colonization

Controlling both organizations and transparency of dense collagen scaffolds.

Easy xeno-free and feeder-free method for isolating and growing limbal stromal and epithelial stem cells of the human cornea

Epithelial and stromal stem cells are required to maintain corneal transparency. The aim of the study was to develop a new method to isolate and grow both corneal stromal (SSC) and epithelial limbal (LSC) stem cells from small human limbal biopsies under culture conditions in accordance with safety requirements mandatory for clinical use in humans. Superficial limbal explants were retrieved from human donor corneo-scleral rims. Human limbal cells were dissociated by digestion with collagenase A, either after epithelial scraping or with no scraping. Isolated cells were cultured with Essential 8 medium (E8), E8 supplemented with EGF (E8+) or Green’s medium with 3T3 feeder-layers. Cells were characterized by immunostaining, RT-qPCR, colony forming efficiency, sphere formation, population doubling, second harmonic generation microscopy and differentiation potentials. LSC were obtained from unscraped explants in E8, E8+ and Green’s media and were characterized by colony formation and expression of PAX6, ΔNP63α, Bmi1, ABCG2, SOX9, CK14, CK15 and vimentin, with a few cells positive for CK3. LSC underwent 28 population doublings still forming colonies. SSC were obtained from both scraped and unscraped explants in E8 and E8+ media and were characterized by sphere formation, expression of PAX6, SOX2, BMI1, NESTIN, ABCG2, KERATOCAN, VIMENTIN, SOX9, SOX10 and HNK1, production of collagen fibrils and differentiation into keratocytes, fibroblasts, myofibroblasts, neurons, adipocytes, chondrocytes and osteocytes. SSC underwent 48 population doublings still forming spheres, Thus, this new method allows both SSC and LSC to be isolated from small superficial limbal biopsies and to be primary cultured in feeder-free and xeno-free conditions, which will be useful for clinical purposes.

Stromal striae: a new insight into corneal physiology and mechanics

We uncover the significance of a previously unappreciated structural feature in corneal stroma, important to its biomechanics. Vogt striae are a known clinical indicator of keratoconus, and consist of dark, vertical lines crossing the corneal depth. However we detected stromal striae in most corneas, not only keratoconus. We observed striae with multiple imaging modalities in 82% of 118 human corneas, with pathology-specific differences. Striae generally depart from anchor points at Descemet’s membrane in the posterior stroma obliquely in a V-shape, whereas in keratoconus, striae depart vertically from posterior toward anterior stroma. Optical coherence tomography shear wave elastography showed discontinuity of rigidity, and second harmonic generation and scanning electron microscopies showed undulation of lamellae at striae locations. Striae visibility decreased beyond physiological pressure and increased beyond physiological hydration. Immunohistology revealed striae to predominantly contain collagen VI, lumican and keratocan. The role of these regions of collagen VI linking sets of lamellae may be to absorb increases in intraocular pressure and external shocks.

Conventional and Iontophoresis Corneal Cross-Linking for Keratoconus: Efficacy and Assessment by Optical Coherence Tomography and Confocal Microscopy

PURPOSE

To compare the efficacy, safety, and microstructural corneal changes during 2 years after conventional corneal collagen cross-linking (C-CXL) and transepithelial corneal CXL by iontophoresis (I-CXL) for keratoconus.

METHODS

Eighty eyes of 80 patients with progressive keratoconus were treated by C-CXL (n = 40) or I-CXL (n = 40). Patients were investigated before surgery and 1, 3, 6, 12, and 24 months after treatment. We measured central corneal thickness and maximal simulated keratometry values (Kmax) and performed specular microscopy and in vivo confocal microscopy at each time point. The demarcation line was assessed 1 month after treatment.

RESULTS

Kmax remained stable after I-CXL during the entire study period (P = 0.56), whereas the average keratometry increased by 0.2 diopter (50.9 ± 5.6-51.1 ± 5.2). Kmax significantly decreased 1 (P = 0.02) to 2 years (P < 0.01) after C-CXL, with an average decrease of 1.1 diopters (49.9 ± 4.5-48.8 ± 4.2). The failure rate of I-CXL was 20% and that of C-CXL 7.5%. The demarcation line was superficially visible in 35% of cases after I-CXL compared with 95% of cases after C-CXL. Endothelial cell density and central corneal thickness remained stable during the entire study period. The change in Kmax 2 years after C-CXL and I-CXL and the preoperative Kmax were negatively correlated (r = 0.14, P = 0.013, and r = 0.17, P = 0.007, respectively).

CONCLUSIONS

I-CXL halted progression of keratoconus less efficiently than did C-CXL after 2 years of follow-up. Longer prospective studies are still needed to ensure I-CXL efficacy.

Endothelial Survival After Descemet Membrane Endothelial Keratoplasty: Effect of Surgical Indication and Graft Adherence Status

IMPORTANCE

This study evaluates the longevity of Descemet membrane endothelial keratoplasty (DMEK) grafts in terms of endothelial survival and endothelial failure.

OBJECTIVE

To determine endothelial survival and its association with the indication for surgery and/or partial graft detachment in DMEK.

DESIGN, SETTING, AND PARTICIPANTS

Retrospective cross-sectional study of data collected from August 8, 2006, until June 17, 2015, at a tertiary referral center. A total of 352 eyes were evaluated up to 8 years after DMEK for Fuchs endothelial corneal dystrophy (FECD; n = 314), bullous keratopathy (BK; n = 31), and failed previous endothelial graft (n = 7), of which 314 eyes had complete graft attachment and 38 eyes had partial graft detachment (one-third of the graft surface area or less). Endothelial cell density was measured with specular microscopy, and Kaplan-Meier survival estimates were based on eyes with endothelial failure. Endothelial survival was followed up to 8 years after DMEK.

MAIN OUTCOMES AND MEASURES

Endothelial cell density, endothelial failure, and endothelial survival.

RESULTS

Endothelial cell density decreased to a mean (SD) of 952 (366) and 771 (321) cells/mm2 at 7 and 8 years postoperatively, respectively. Higher endothelial cell densities were found in eyes with FECD compared with those with BK (estimated mean difference, 261 cells/mm2; 95% CI, 118-404; P = .003) and in eyes with attached grafts compared with those with partially detached grafts (estimated mean difference, 330 cells/mm2; 95% CI, 208-452; P < .001), until 8 years. In 11 eyes (3.1%) that had concomitant ocular pathology, endothelial failure occurred within 4 years after DMEK. The overall graft survival probability was 0.96 at 5 and 8 years (95% CI, 0.94-0.99). At 8 years, better survival rates were found in eyes with FECD than in those with BK (survival probability, 0.97 [95% CI, 0.95-0.99] vs 0.84 [95% CI, 0.70-0.99], respectively); until the same follow-up, survival probabilities in eyes with attached and partially detached grafts were 0.97 (95% CI, 0.95-0.99) and 0.91 (95% CI, 0.82-0.99), respectively.

CONCLUSIONS AND RELEVANCE

Endothelial decay was higher in eyes with a partial graft detachment than in those with attached grafts and lower in eyes with FECD than in those with BK. Endothelial failure only occurred in eyes with concomitant ocular pathology. These results suggest that eyes with DMEK that have undergone surgery for FECD with a completely attached graft may have an excellent prognosis.

Iris-fixated phakic intraocular lens implantation to correct myopia and a predictive model of endothelial cell loss

PURPOSE

To report long-term results of Artisan phakic intraocular lens (pIOL) to correct myopia and to propose a model predicting endothelial cell loss after pIOL implantation.

SETTING

Quinze-Vingts National Ophthalmology Hospital, Paris, France.

DESIGN

Retrospective, interventional case series.

METHODS

Uncorrected distance visual acuity (UDVA), corrected distance visual acuity (CDVA), and central endothelial cell count (ECC) were determined before and at yearly intervals up to 5 years after pIOL implantation. Linear model analysis was performed to present a model that describes endothelial cell loss as a linear decrease and an additional decrease depending on postoperative loss.

RESULTS

A total of 49 patients (68 eyes) implanted with pIOLs from January 2000 to January 2009 were evaluated. The mean preoperative and final spherical equivalent (SE) were -13 ± 4.10 and -0.75 ± 0.74 diopters (D), respectively. The mean preoperative and final central ECC were 2629 ± 366 and 2250 ± 454 cells/mm(2), respectively. There were no intraoperative complications for any of the eyes. One eye required surgery for repositioning the pIOL, and 1 eye required pIOL exchange for postoperative refractive error. The model predicted that for patients with preoperative ECC of 3000, 2500, and 2000 cells/mm(2), a critical ECC of 1500 cells/mm(2) will be reached at 39, 28, and 15 years after implantation, respectively.

CONCLUSIONS

Implantation of the pIOL was an effective and stable procedure after 5 years of follow-up. The presented model predicted EC loss after pIOL implantation, which can assist ophthalmologists in patient selection and follow-up.

FINANCIAL DISCLOSURE

The authors report no conflict of interest.

Three Different Protocols of Corneal Collagen Crosslinking in Keratoconus: Conventional, Accelerated and Iontophoresis

Keratoconus is a bilateral and progressive corneal ectasia. In order to slow down its progression, corneal collagen cross-linking (CXL) has recently been introduced as an efficient treatment option. In biological and chemical sciences, crosslinking refers to new chemical bonds formed between reactive molecules. Hence, the aim of corneal collagen CXL is to synthetically increase the formation of crosslinks between collagen fibrils in the corneal stroma. Despite the fact that the efficiency of the conventional CXL (C-CXL) protocol has already been shown in several clinical studies, it might benefit from improvements in duration of the procedure and removal of corneal epithelium. Hence, in order to provide a coherent evaluation of two new and optimized CXL protocols, we studied keratoconus patients who had undergone one of the three CXL treatments: iontophoresis (I-CXL), accelerated CXL (A-CXL), and conventional CXL (C-CXL). A-CXL is a 6 time faster CXL procedure using a ten time higher UVA irradiance but still including an epithelium removal. Iontophoresis is a transepithelial non-invasive technique in which a small electric current is applied to improve riboflavin penetration throughout the cornea. Using anterior segment optical coherence tomography (AS OCT) and in vivo confocal microscopy (IVCM), we conclude that regarding the depth of treatment penetration, conventional CXL protocol remains the standard for treating progressive keratoconus. Accelerated CXL seems to be a quick, effective and safe alternative to treat thin corneas. The use of iontophoresis is still being investigated and should be considered with greater caution.

Decreased Corneal Sensation and Subbasal Nerve Density, and Thinned Corneal Epithelium as a Result of 360-Degree Laser Retinopexy

PURPOSE

To assess the effects of 360-degree laser retinopexy on human corneal subbasal nerve plexus and to investigate correlations among corneal subbasal nerve plexus density, corneal epithelial thickness, and corneal sensitivity.

DESIGN

Prospective, observational, nonrandomized study.

PARTICIPANTS

A total of 15 eyes of 15 patients who underwent pars plana vitrectomy (PPV) with 360-degree laser retinopexy for retinal detachment (RD) and 15 eyes of 15 patients who underwent PPV for macular hole (MH) without laser treatment.

METHODS

Corneal sensation, corneal epithelial thickness, and corneal subbasal nerve plexus density were assessed before surgery and 6 months after surgery via in vivo confocal microscopy, anterior segment optical coherence tomography (AS-OCT), and Cochet-Bonnet esthesiometry (Luneau Ophthalmologie, Paris, France).

MAIN OUTCOME MEASURES

Corneal subbasal nerve plexus density, corneal epithelium thickness, and central corneal sensitivity.

RESULTS

Compared with baselines values, the mean subbasal nerve density (P < 0.001), mean corneal epithelium thickness (P = 0.006), and mean corneal sensitivity (P < 0.001) in the RD group were significantly decreased 6 months after surgery by 74.3%, 4.7%, and 56.6%, respectively. Conversely, in the MH group there were no significant differences in the mean subbasal nerve density (P = 0.34), mean corneal epithelial thickness (P = 0.19), and mean corneal sensitivity (P = 0.42) between preoperative and 6-month postoperative values (0.7%, 0.4%, and 0.8%, respectively). The postoperative decrease in corneal subbasal nerve density after laser retinopexy was associated with a decrease in corneal epithelium thickness (r(2) = 0.42; P = 0.006) and a decrease in corneal sensitivity (r(2) = 0.48; P = 0.004). The postoperative decrease in corneal sensitivity poorly correlated with the decrease in corneal epithelial thickness (r(2) = 0.24; P = 0.045). Postoperative corneal nerve density decreased as total laser energy increased (r(2) = 0.51; P = 0.002).

CONCLUSIONS

Subbasal corneal nerve plexus density decreases after 360-degree laser retinopexy and is accompanied by epithelium thinning and decreased corneal sensation. Surgeons should eschew heavy confluent retinal laser treatment, and corneal sensitivity should be assessed postoperatively to determine whether significant anesthesia has occurred. In such instances, prophylactic measures may be warranted against the development of neurotrophic ulcers.

Fourier-domain optical coherence tomography imaging in corneal epithelial basement membrane dystrophy: a structural analysis

PURPOSE

To investigate the features of corneal epithelial basement membrane dystrophy using spectral-domain optical coherence tomography (SD OCT) and to examine the reliability of SD OCT in distinguishing epithelial basement membrane dystrophy from the normal cornea.

DESIGN

Diagnostic test study.

METHODS

Forty-five individuals with epithelial basement membrane dystrophy and 45 age- and sex-matched controls with normal corneas were examined, and SD OCT scans of their corneas were performed. In vivo confocal microscopy was performed to confirm or rule out the diagnosis of epithelial basement membrane dystrophy. The structural corneal changes occurring in eyes with epithelial basement membrane dystrophy based on SD OCT findings were described.

RESULTS

Epithelial abnormalities were observed in 86 of 87 eyes with epithelial basement membrane dystrophy (45 patients) on SD OCT scans. The 2 main features were the presence of an irregular and thickened epithelial basement membrane duplicating or insinuating into the corneal epithelium layer, or both, and the presence of hyperreflective dots. In some cases, we detected hyporeflective spaces between the corneal epithelial layer and the Bowman layer similar to a corneal epithelial detachment. This corneal epithelial detachment sometimes was associated with a cleavage with a stair-step appearance within the corneal epithelial layer. We found a perfect correlation between in vivo confocal microscopy and SD OCT findings in the diagnosis of epithelial basement membrane dystrophy (κ = 0.98).

CONCLUSIONS

SD OCT provides an accurate assessment of the structural changes occurring in eyes with epithelial basement membrane dystrophy. These changes, visible on SD OCT scans, are easily detectable and permit an accurate diagnosis, especially in patients with no biomicroscopically visible corneal changes.

Imported pythium insidiosum keratitis after a swim in Thailand by a contact lens-wearing traveler

A 30-year-old woman with a history of contact lens wear and exposure to swimming pool water in Thailand presented with a non-responsive, progressive corneal ulcer of the right eye. Confocal microscopy evidenced septate linear branching structures, raising suspicion of fungal keratitis. She was promptly treated with topical antibiotics and both topical and intravenous caspofungin plus voriconazole. Worsening of the clinical picture after 1 month of intensive medical therapy led to a large therapeutic penetrating keratoplasty being performed. Corneal cultures grew a mold-like organism, which was identified by sequencing as Pythium insidiosum, an aquatic oomycete. After 4 years of follow-up, the graft exhibits no infection relapse, but graft transparency has been lost after two rejection episodes. Keratoplasty combined with antifungal treatment may offer a cure to P. insidiosum keratitis, although long-term preservation of corneal transparency is difficult to obtain.

Optical coherence tomography and confocal microscopy following three different protocols of corneal collagen-crosslinking in keratoconus

PURPOSE

We compared the efficacy and early morphological changes in the cornea following conventional (C-CXL), transepithelial by iontophoresis (I-CXL), and accelerated (A-CXL) collagen cross-linking in keratoconus.

METHODS

A total of 45 eyes of 45 patients with progressive keratoconus who underwent corneal collagen crosslinking (CXL) was divided into three groups: C-CXL (n = 15), A-CXL (n = 15), and I-CXL (n = 15). Patients were examined before surgery and at 1-, 3-, and 6-month intervals following surgery. Density of corneal sub-basal nerves, anterior and posterior keratocytes, corneal endothelium, demarcation line depth, and maximal simulated keratometry values (Kmax) were all assessed.

RESULTS

Compared to preoperative values, the mean corneal sub-basal nerve and anterior stromal keratocyte densities were significantly lower at 6 months in the C-CXL and A-CXL groups (P < 0.001), whereas they returned to preoperative values in the I-CXL group (P = 0.083 and P = 0.909, respectively). The corneal demarcation line was visible 1 month after surgery in 93% of cases (mean depth, 302.8 ± 74.6 μm) in the C-CXL group, 87.5% (mean depth, 184. 2 ± 38.9 μm) in the A-CXL group, and 47.7% (mean depth, 212 ± 36.5 μm) in the I-CXL group (P = 0.006). There were no significant differences between confocal microscopy and optical coherence tomography measurements of the corneal demarcation line depth (P > 0.05). The Kmax, corneal central thickness, and BSCVA remained stable during the whole study period.

CONCLUSIONS

Iontophoresis was associated with weaker damage of corneal sub-basal nerves and anterior keratocytes compared to conventional procedures, but the demarcation line was present in less than 50% of cases and was more superficial than with the traditional procedure.

[Acanthamoeba keratitis]

Early diagnosis and appropriate therapy are key elements for a good prognosis in Acanthamoeba keratitis (AK). AK should be considered in any case of corneal trauma complicated by exposure to soil or contaminated water, and in all contact lens (CL) wearers. A presumptive diagnosis of AK can be made clinically and with in vivo confocal microscopy, although a definitive diagnosis requires identification of Acanthamoeba on direct scraping, histology, or identification of Acanthamoeba DNA by polymerase chain reaction (PCR). We use cysticidal drugs for treating AK because encysted forms are more resistant than trophozoites to treatment. The treatment protocol used a biguanide (PHMB 0.02% or chlorhexidine 0.02%) and a diamidine (propamidine 0.1% or hexamidine 0.1%). New diagnostic modalities and more specific topical anti-amoebic treatments would substantially benefit patients with AK.

A reproducible automated segmentation algorithm for corneal epithelium cell images from in vivo laser scanning confocal microscopy

PURPOSE

To evaluate an automated process to find borders of corneal basal epithelial cells in pictures obtained from in vivo laser scanning confocal microscopy (Heidelberg Retina Tomograph III with Rostock corneal module).

METHODS

On a sample of 20 normal corneal epithelial pictures, images were segmented through an automated four-step segmentation algorithm. Steps of the algorithm included noise reduction through a fast Fourier transform (FFT) band-pass filter, image binarization with a mean value threshold, watershed segmentation algorithm on distance map to separate fused cells and Voronoi diagram segmentation algorithm (which gives a final mask of cell borders). Cells were then automatically counted using this border mask. On the original image either with contrast enhancement or noise reduction, cells were manually counted by a trained operator.

RESULTS

The average cell density was 7722.5 cells/mm(2) as assessed by automated analysis and 7732.5 cells/mm(2) as assessed by manual analysis (p = 0.93). Correlation between automated and manual analysis was strong (r = 0.974 [0.934-0.990], p < 0.001). Bland-Altman method gives a mean difference in density of 10 cells/mm(2) and a limits of agreement ranging from -971 to +991 cells/mm(2) . Visually, the algorithm correctly found almost all borders.

CONCLUSION

This automated segmentation algorithm is worth for assessing corneal epithelial basal cell density and morphometry. This procedure is fully reproducible, with no operator-induced variability.

[The cornea in high axial myopia]

PURPOSE

To compare corneal characteristics of eyes with high myopia with those of eyes with no spherical ametropia using Orbscan and ultrasonic pachymetry.

METHODS

Orbscan and ultrasonic pachymetry values were prospectively recorded in a study group of 105 patients with high myopia (i.e., axial length greater than 26mm in both eyes) and in a control group of 105 patients with no spherical ametropia (absolute value of spherical equivalent less than 1.25D regardless of cylinder value). Astigmatism data were expressed by rectangular coordinates in a dioptric plane. Axis was decomposed in 2 components (WTR/ATR and oblique) which were analyzed by Cos2axis and Sin2axis trigonometric functions. Enantiomorphism (mirror-image symmetry) between fellow eyes was quantified by a Euclidean distance for the location of the thinnest point and by the difference (in absolute value) between 180° and the sum of both axes for astigmatism.

RESULTS

In the study group, the mean axial length and subjective spherical equivalent were, respectively, 27.82±2.14mm (26.00 to 34.06) and -9.00±3.46D (-4.71 to -19.82). The mean corneal astigmatism was +0.92D×91.3° in the study group and +0.65D×89.3° in the control group. The mean corneal cylinder was higher in the study group (1.44D versus 0.91D; P<0.001) whereas axis showed no significant differences between both groups. The mean maximal keratometry was steeper in the study group (44.53D versus 44.13D; P=0.03) whereas the mean keratometry and minimal keratometry displayed no significant differences between both groups. No significant differences in central corneal thickness (540.2μm versus 546.9μm; P=0.10), peripheral corneal thickness, corneal diameter, corneal irregularity, asphericity, and irregular astigmatism were found between both groups. There were no significant differences in enantiomorphism parameters between both groups. In the study group, correlation with axial length was significant only for spherical equivalent (r=-0.86; P<0.001) and corneal cylinder (r=0.16; P=0.04).

CONCLUSION

High myopia exhibits corneal characteristics similar to corneas of eyes with no spherical ametropia, except for toricity. While the posterior segment elongates, development of high myopia appears not to affect corneal characteristics. Corneal toricity may be associated with evolution toward high myopia by perturbing mechanisms of emmetropization.

Kinetics of expansion of human limbal epithelial progenitor cells in primary culture of explants without feeders

The aims of this study were to determine whether human limbal explant cultures without feeder cells result in expansion of epithelial progenitors and to estimate the optimal expansion time for progenitor cells. Limbal explants from ten human corneas were cultured for 7, 9, 11, 14, 18, and 21 days. Limbal explants from two corneas were enzymatically dissociated or directly cultured for 14 days. Progenitor cells were characterized by their ability to form colonies, by immunocytochemistry, and by quantitative real-time polymerase chain reaction. Colonies were identified after 9, 11, 14, and 18 days of culture, but not after 21 days. The number of colonies per explant was significantly higher after 14 days than after 9 and 21 days. The mean percentage of seeded cells giving rise to clones was 4.03% after 14 days of culture and 0.36% for non-cultured dissociated limbal epithelial cells. The number of cells giving rise to clones per cornea significantly increased from an average of 2275 for non-cultured cells to 24266 for cells cultured for 14 days. Immunocytochemical analysis detected positive staining for cytokeratin (CK) 3, CK5/6/8/10/13/18, CK19, vimentin, p63, and p63α, in both cultures and clones. CK3 expression increased significantly with culture time. Transcript expression was observed for CK3, CK19, vimentin, and Delta N p63α at each culture time point, both in cultures and clones. The optimal culture time for limbal explants in cholera toxin-free Green medium without feeder cells was 14 days leading to the expansion of progenitors.

[Epithelial basement membrane dystrophy diagnosed following LASIK surgery]

A 48-year-old woman with no significant past history underwent bilateral simultaneous laser in situ keratomileusis for correction of her myopia. On the tenth postoperative day, the patient complained of visual decrease and photophobia. Slit lamp exam showed corneal epithelial irregularities. Confocal microscopy was performed and revealed a characteristic appearance of epithelial basement membrane dystrophy (EBMD). The patient was successfully treated with artificial tears and autologous serum eyedrops. EBMD may be missed before LASIK surgery, even after a careful pre-operative examination. Exacerbation of EBMD after LASIK surgery is rare. It should be considered when unexplained corneal epithelial defects or irregularities occur following LASIK. Confocal microscopy is very useful to confirm the diagnosis.

[Relationships between refractive parameters: sphere, cylinder and axis]

PURPOSE

To analyze the relationships between refractive parameters as well as the relationship between fellow eyes in a normal population.

METHODS

Both subjective refraction and auto-refractometry data of 500 patients were prospectively recorded. Refraction data were analyzed on three rectangular coordinates in a dioptric space. WTR/ATR ratio of axis was quantified by the Cos2axis function. Enantiomorphism (mirror-image symmetry) between fellow eye axes was quantified by the absolute value of the difference between 180° and the sum of both axes.

RESULTS

Mean refraction and mean cylinder were -1.74D (+0.28D × 91.5°) and 0.81 ± 0.89D respectively. The spherical component had no significant influence on refractive astigmatism (r(s)≤ 0.07, P ≥ 0.07) except for high spherical ametropia. Eyes with spherical equivalent greater than 4D (in absolute value) demonstrated higher cylinder (1.15D vs 0.84D, P<0.001). Cylinder influenced the WTR/ATR ratio (r(s)=-0.25, P<0.001) and the enantiomorphism (r(s)=0.36, P<0.001). Age also influenced the WTR/ATR ratio (r(s)=0.27, P<0.001) and the enantiomorphism (r(s)=0.14, P<0.001). Axes were more likely WTR and enantiomorphic when the cylinder was high and the subject young. Oblique axes were less enantiomorphic (35.5° vs 20.6°, P<0.001) and were associated with lower cylinder (0.56D vs 0.98D, P<0.001). Correlation between fellow eyes was significant for cylinder (r(s)=0.66, P<0.001) and for spherical equivalent (r(s)=0.96, P<0.001). Gender had no significant influence on refraction (P>0.12) except for spherical equivalent (relative hyperopia of +0.17D, P=0.04 in females).

CONCLUSION

The spherical component of the refraction appears to be independent of the refractive astigmatism except for high spherical ametropia. Cylinder influences somewhat the WTR/ATR ratio of axis and the enantiomorphism. Relationships between refractive parameters are weak in comparison to the fellow eye relationships.

New strategy for rapid diagnosis and characterization of keratomycosis

PURPOSE

The first-line therapy for patients with keratitis is different for bacteria, filamentous fungi, and yeasts. The timely onset of treatments depends on rapid and accurate diagnosis. However, fungal cultures produce high rates of false-negative results. Nucleic acid amplification techniques (polymerase chain reaction [PCR]) improve fungal diagnosis performance, but they require complex postamplification procedures to differentiate filamentous fungi from yeasts or to identify the agent. The objective of this work was to develop a new diagnostic strategy based on real-time PCR high-resolution melting (HRM) analysis that in 1 run (a) detects and semiquantifies yeasts and filamentous fungi, (b) differentiates yeasts from filamentous fungi, and (c) discriminates among relevant species of yeasts.

DESIGN

Experimental study to compare HRM diagnosis performances with microscopic examination of corneal scrapings and fungal culture.

PARTICIPANTS AND CONTROLS

High-resolution melting detection limits and specificity were assessed with (a) isolated strains; (b) agents (other than fungi) producing keratitis; (c) corneal scrapings from fungal keratitis (culture positive and negative); and (d) corneal scrapings from bacterial, viral, or Acanthamoeba keratitis.

METHODS

The DNA extracted from cornea specimens was mixed with primers diluted in the MeltDoctor HRM Master Mix (Applied Biosystems, Paris, France) in 2 tubes, the first for yeasts, containing the forward primer CandUn (5'CATGCCTGTTTGAGCGTC) and the reverse primer FungUn2 (5'TCCTCCGCTTATTGATATGCT), and the second for filamentous fungi, containing the forward primer FilamUn1 (5'TGCCTGTCCGAGCGTCAT) and FungUn2. Molecular probes were not necessary. The yields of DNA extraction and the PCR inhibitors were monitored by adding internal controls to each sample.

MAIN OUTCOME MEASURES

Detection of fungi in corneal samples by HRM.

RESULTS

High-resolution melting consistently detects the equivalent of 0.1 colony-forming units /ml of yeasts and filamentous fungi, differentiates filamentous fungi from yeasts, and discriminates among relevant species of yeasts. High-resolution melting sensitivity and specificity were 100% for culture-positive samples, detecting and characterizing fungi in 7 of 10 culture-negative suspected fungal keratitis.

CONCLUSIONS

High-resolution melting is a new, sensitive, specific, and inexpensive test that detects fungi and differentiates filamentous fungi from yeasts directly from clinical specimens in less than 2.30 hours after DNA extraction.

[Fungal keratitis caused by Cylindrocarpon lichenicola]

We report a case of a 67-year-old woman with no significant past ocular history, who was referred for management of an unresponsive microbial keratitis resulting from trauma with a piece of clothing fabric 1 month previously in Portugal and worsening despite topical fortified antibiotics. On examination, visual acuity was limited to "light perception". Slit lamp examination revealed an 11×11mm full-thickness corneal infiltrate. Confocal images showed branching hyphae suggestive of a fungal infection. Fungal cultures of corneal scrapings revealed growth of Cylindrocarpon lichenicola, a saprophytic, filamentous fungus, which is an unusual cause of keratitis. Despite aggressive antifungal therapy with voriconazole and amphotericin B, she required penetrating keratoplasty for impending corneal perforation. Follow-up was uneventful, with no recurrence at 1 year. Fungal infections must be suspected in all corneal ulcers of traumatic etiology. Specific cultures and confocal microscopy must be performed early, so as to enable early treatment modification.

[Recurrence of an idiopathic vasocentric epiretinal membrane: clinical and surgical particularities]

The vasocentric epiretinal membranes (ERM) are idiopathic ERM centered on retinal blood vessels, described mainly in young patients. We report a case of a 70-year-old patient who presented with a decrease in visual acuity secondary to a vasocentric epiretinal membrane. A successful vitrectomy and ERM removal were performed. Four years after surgery, a contractile ERM centered on the superior temporal blood vessel occurred and was associated with retinal distortions at the posterior pole. The second surgery combined removal of the recurrent ERM, which was adherent to the temporal vessels, and peeling of the internal limiting membrane in the macular area. Although there was visual recovery, the patient is still suffering from metamorphopsia 2 years after surgery. The vasocentric ERM have a poor visual outcome and a high risk of recurrence in comparison with other ERM disorders. This case report describes the main clinical and surgical characteristics of this type of membrane.

Reproducibility of viscoelastic property and intraocular pressure measurements obtained with the Ocular Response Analyzer

PURPOSE

To analyse the reproducibility of corneal hysteresis (CH), corneal resistance factor (CRF), Goldmann-correlated intraocular pressure (IOPg) and corneal-compensated intraocular pressure (IOPcc) obtained with the ocular response analyzer (ORA).

METHODS

This is a prospective study, nonmasked, of eight successive examinations with the ORA device in 60 normal eyes. Using 30 eyes (one eye per subject), the reproducibility was assessed by comparing the first series of four examinations to the second four and by calculating the within-subject coefficient of variation. The correlation and difference with the fellow eye were analysed, respectively.

RESULTS

The mean values were 10.7 ± 1.8 mmHg, CRF; 10.6 ± 1.6 mmHg, CH; 15.9 ± 3.9 mmHg, IOPg and 16.2 ± 3.7 mmHg, IOPcc. The reproducibility was significantly different for CRF (5.2 ± 5.9%), CH (7.3 ± 8.6%), IOPg (7.7 ± 6.7%) and IOPcc (10.1 ± 8.0%); p < 0.001. Considering the reproducibility, CRF correlated with CH (rs = 0.55; p < 0.001) and showed to be independent of IOPg and IOPcc. The score spread was best for CRF (2.6 ± 1.5 mmHg; 24.0%) compared to IOPg (4.3 ± 1.5 mmHg; 28.1%) and CH (3.1 ± 1.7 mmHg; 29.9%) and worst for IOPcc (5.5 ± 2.5 mmHg; 34.4%). The lowest difference with the fellow eye was observed for CRF (5.0%; p = 0.09). The correlation with the fellow eye was high, especially for IOPcc and CRF (rs > 0.9; p < 0.001) followed by IOPg and CH (rs > 0.8; p < 0.001).

CONCLUSION

The ORA device provides reproducible information on viscoelastic properties of the cornea in normal eyes notably CRF and CH. IOPcc was less reproducible. Four measurements per eye were necessary to reach a 10% precision and six for 5%.

Human epithelial cell cultures from superficial limbal explants

PURPOSE

To study the kinetics of growth and the phenotype of cells cultured from human limbal explants in a cholera toxin-free medium with no feeder cell layer.

METHODS

Human organ-cultured corneas were used to prepare limbal explants (full-thickness and superficial limbal explants) and corneal stromal explants. Cell growth kinetics and phenotypes were assessed by cultivating explants in cholera toxin-free Green medium. Epithelial and progenitor cell markers were assessed by immunocytochemistry, flow cytometry, and Reverse Transcription and Polymerase Chain Reaction (RT-PCR).

RESULTS

The successful epithelial cell growth rates from full thickness limbal explant and superficial limbal explant tissues were 41 and 86%, respectively (p=0.0001). The mean cell area and the percentage of small cells in superficial and full-thickness explant cultures were, respectively, 317 µm(2) and 429 µm(2), and 8.9% and 1.7% (p<0.001). The percentage of positive cells in superficial and full-thickness limbal explant cultures as assessed by immunocytochemistry were the following: broad spectrum cytokeratins (cytokeratins 4, 5, 6, 8, 10, 13, and 18 [MNF116]), 82%/37% (p=0.01); cytokeratin 3 (CK3), 74%/25% (p=0.009); cytokeratin 19 (CK19), 46%/25% (p=0.19); vimentin, 56%/53% (p=0.48); delta N p63α, 54%/0% (p<0.001); and ABCG2, 5%/0% (p=0.1). Flow cytometry showed a higher percentage of small cells, a higher percentage of MNF116+ cells, and stronger expression of progenitor-associated markers in superficial than in full-thickness explant cultures. For superficial limbal explant cultures, analysis of the expression profiles for various mRNAs at the end of 21 days of culture showed high levels of expression of the mRNAs encoding CK3, vimentin, and CK19. The expression of mRNA of delta N p63α and ABCG2 was weaker. Cultures obtained from full-thickness limbal explants featured no expression of mRNA of CK19, delta N p63α, and ABCG2, whereas mRNAs encoding CK3 and vimentin were detected. Human corneal stromal explants cultured with the same medium featured late cell growth, large mean cell area (2,529 µm(2)), no expression of cytokeratins, delta N p63α, and ABCG2, and high expression of vimentin.

CONCLUSIONS

Superficial limbal explants appear to be superior to full-thickness limbal explants for growing human limbal epithelial cells. Preparation of explants using surgical facilities (i.e., operating microscope and microsurgical blades) led to a dramatic increase in the percentage of successful cultures, higher epithelial cell growth, decreased fibroblast contamination, and better preservation of limbal epithelial progenitors.