Keratoconus and the Impact of Treatment on Patients' Quality of Life: A Qualitative Study.

INTRODUCTION: Keratoconus has a significant impact on patients' quality of life (QoL), from diagnosis to the advanced stages of the disease. The aim of this research was to identify domains of QoL affected by this disease and its treatment. METHODS: Phone interviews were conducted using a semi-structured interview guide, with patients with keratoconus stratified according to their current treatment. A board of keratoconus experts helped identify the guide's main themes. RESULTS: Thirty-five patients (rigid contact lenses, n = 9; cross-linking, n = 9; corneal ring implants, n = 8; and corneal transplantation, n = 9) were interviewed by qualitative researchers. Phone interviews revealed several QoL domains affected by the disease and its treatments: "psychological", "social life", "professional life", "financial costs" and "student life". All domains were impacted, independently of the treatment history. Few differences were found between treatment regimens and keratoconus stages. Qualitative analysis enabled the development of a conceptual framework based on Wilson and Cleary's model for patient outcomes common to all patients. This conceptual model describes the relationship between patients' characteristics, their symptoms, their environment, their functional visual impairment and the impact on their QoL. CONCLUSIONS: These qualitative findings supported the generation of a questionnaire to evaluate the impact of keratoconus and its treatment on patients' QoL. Cognitive debriefings confirmed its content validity. The questionnaire is applicable for all stages of keratoconus and treatments and may help tracking change over time in regular clinical settings. Psychometric validation is yet to be performed before its use in research and clinical practices.

Postoperative Corneal Epithelial Remodeling After Intracorneal Ring Segment Procedures for Keratoconus: An Optical Coherence Tomography Study.

PURPOSE: To assess epithelial corneal remodeling by anterior segment optical coherence tomography (AS-OCT) after intracorneal ring segments (ICRS) implantation in keratoconic eyes. METHODS: This prospective observational study included patients with keratoconus receiving ICRS of different arc lengths according to their tomographic pattern. AS-OCT and corneal topography (Scheimpflug camera) were performed before and 1, 3, and 6 months after surgery. Corneal pachymetry mapping was performed and total corneal and epithelial thicknesses (3-mm central and 16 points on 6-mm zone) were measured over the pupil center using AS-OCT. Topographic parameters were also assessed. RESULTS: A total of 68 keratoconic eyes were analyzed (Amsler-Krumeich stages 1 to 4) in four groups of 17 eyes: 210° ICRS, 320° ICRS, double 160° ICRS, and single 160° ICRS. Corneal pachymetry mapping revealed that epithelial thickness increased significantly in the internal zones juxtaposed to the ICRS without smoothing during the postoperative period (P < .05). Mean maximum epithelial thickness increased from 67 ± 6 to 79 ± 7 µm for 210° ICRS, 66 ± 9 to 82 ± 4 µm for 320° ICRS, 63 ± 6 to 78 ± 7 µm for double 160° ICRS, and 62 ± 5 to 77 ± 5 µm for single 160° ICRS (P < .0001). Significant epithelial thickening at the apex of the cone was observed in all groups (P < .05). CONCLUSIONS: Significant epithelial thickening occurs after ICRS implantation adjacent to the ICRS to compensate for the ridge created with a thickening of epithelium over the cone due to regularization of the stromal surface. [J Refract Surg. 2021;37(6):404-413.].

Corneal Remodeling After Myopic SMILE: An Optical Coherence Tomography and In Vivo Confocal Microscopy Study.

PURPOSE: To study corneal remodeling during the first 6 months after myopic small incision lenticule extraction (SMILE) with a 10% overcorrection nomogram, by spectral-domain optical coherence tomography (SD-OCT) and in vivo confocal microscopy (IVCM). METHODS: This prospective non-randomized observational study included 60 eyes from 30 patients treated by SMILE for low to moderate myopia. A 10% overcorrection nomogram was applied for all eyes. Epithelial and corneal thickness maps were obtained within the central 6 mm, by SD-OCT, at each visit. Lenticule thickness was calculated by subtracting the postoperative central stromal thickness from the preoperative central stromal thickness. IVCM was performed at each visit. RESULTS: The mean surgical refractive correction was -3.99 ± 1.50 diopters (D) before and -0.09 ± 0.37 D after surgery. Central epithelial thickness increased from 53.7 ± 4.0 to 57.1 ± 4.1 µm at 6 months after SMILE (P < .001). The measured lenticule thickness was 16 ± 6.1 µm less than the programmed lenticule thickness (P < .001). Both central epithelial hyperplasia and the mismatch between measured and programmed lenticule thickness were positively correlated to the degree of myopia (r2 = 0.60, P < .001 and r2 = 0.47, P < .001, respectively). Fibrosis at the interface was not correlated with epithelial thickening (r2 = 0.06, P = .29) or lenticule thickness error (r2 = 0.07, P = .22). CONCLUSIONS: Both epithelial thickening and the mismatch between the targeted and achieved lenticule thickness resulted in a slight undercorrection with a 10% overcorrection nomogram in low and moderate myopia. Fibrosis at the interface was not responsible for lenticule thickness error. Additional overcorrection is required to increase accuracy. [J Refract Surg. 2020;36(9):597-605.].

Presbyopia management with Q-factor modulation without additive monovision: One-year visual and refractive results.

PURPOSE: To analyze refractive results after hyperopic presbyopia surgery by Q-factor modulation without additive monovision. SETTING: Quinze-Vingts National Ophthalmology Hospital, Paris, France. DESIGN: Prospective nonrandomized study. METHODS: Forty-five hyperopic presbyopic patients not tolerating monovision were included. The target for the dominant eye was emmetropia, whereas that for the nondominant eye was emmetropia associated with a target Q factor of -0.8. The postoperative follow-up included assessments of spherical equivalent (SE) refraction, monocular and binocular corrected and uncorrected (UDVA) distance visual acuities, and binocular corrected and uncorrected (UNVA) near visual acuities. Corneal pachymetry, topography, aberrometry and an analysis of patient satisfaction were performed at the 12-month examination. RESULTS: The study comprised 90 eyes of 45 consecutive patients. The mean age at surgery was 53.8 years ± 4.99 (SD). The mean preoperative SE was +2.33 ± 1.16 diopters (D) in the dominant eyes and +2.26 ± 1.17 D in the nondominant eyes. At 12 months postoperatively, 42 patients (93%) had a binocular UDVA of Snellen 20/20 and 37 patients (82%) had a binocular UNVA of Jaeger 2 (Parinaud 3). The mean SE at 12 months was -0.22 ± 0.35 D in the dominant eyes (P < .0001) and -0.83 ± 0.50 D in the nondominant eyes (P < .0001). Two eyes required retreatment. Overall, 39 patients (87%) said that they were satisfied and would recommend the intervention. CONCLUSION: The Q-factor modulation without additive monovision aims to compensate for presbyopia by changing the Q factor of the nondominant eye to generate a greater depth of field in hyperopic presbyopic patients who are unable to tolerate monovision. The visual outcomes and quality of vision were satisfactory, and only a few patients required additional correction.

Deep Intrastromal Arcuate Keratotomy With In Situ Keratomileusis (DIAKIK) for the Treatment of High Astigmatism After Keratoplasty: 2-Year Follow-up.

PURPOSE: To describe 2-year results of deep intrastromal arcuate keratotomy with in situ keratomileusis (DIAKIK) for the treatment of high astigmatism after keratoplasty. METHODS: This prospective study included 20 eyes from 20 patients presenting with high astigmatism after keratoplasty. All were treated by two-step femtosecond laser surgery, with two intrastromal arcuate keratotomies and a corneal flap, followed a few months later by excimer photoablation after reopening of the flap. RESULTS: At 24 months, both uncorrected (UDVA) and corrected (CDVA) distance visual acuity had improved from 1.12 ± 0.42 logMAR (20/200 Snellen) before surgery to 0.58 ± 0.23 logMAR (20/80 Snellen) (P < .001) and from 0.31 ± 0.26 logMAR (20/40 Snellen) to 0.20 ± 0.20 logMAR (20/32 Snellen) (P = .04), respectively. The mean spherical equivalent improved from -5.01 ± 4.35 to -1.54 ± 2.42 diopters. The mean efficacy index was 0.63. The mean correction index was 0.93 ± 0.32. The mean flattening index was 1.09 ± 0.75 and the mean safety index was 1.39. No graft rejection or epithelial ingrowth was observed. CONCLUSIONS: This two-step procedure was an effective treatment for high astigmatism after keratoplasty. The use of both femtosecond and excimer lasers helped to avoid some complications that would have jeopardized the grafts. Refractive and topographic stability was good 2 years after surgery. [J Refract Surg. 2019;35(4):239-246.].

True exposure to lead at the tap: Insights from proportional sampling, regulated sampling and water use monitoring.

This work aimed to evaluate the ability of four regulatory sampling protocols to accurately determine weekly water lead levels (WLLs) of exposure at the kitchen tap in twenty-nine households with or without a lead service line (LSL). Proportional sampling was used as the gold standard to which the other protocols, 5-min flush, 30-min stagnation, 6-h stagnation and random daytime were compared. Random daytime samples provided mean WLLs closest to true exposure in the households monitored overall compared to other sampling protocols. Strikingly, mean WLLs after 5 min of flushing underestimated lead exposure by 47%. Supporting these observations, water usage patterns revealed that full flushing only occurs in 3.4% of usage events within the service line and in 0.26% at the tap. The time between usage events in the service line was approximately 30 min but the 30-min protocol tended to slightly underestimate WLLs. These differences were explained by flushing prior to the 30-min stagnation sampling, which limited the contribution of the LSL to WLLs. Furthermore, the average stagnation at the kitchen time was 106 min and usage events rarely exceeded the water volume within premise plumbing (1.1 L). Mean WLLs after 6 h of stagnation without flushing overestimated exposure by 29% but provided a conservative indicator of WLLs of exposure.

Lead and copper release from full and partially replaced harvested lead service lines: Impact of stagnation time prior to sampling and water quality.

Partial lead service line replacement (PLSLR) results in the addition of a new galvanic connection and can increase lead concentrations at the tap. Focus has been given to minimizing lead release after PLSLR, but little information is available on the impact of lead remedial actions on copper concentrations, especially before passivation occurs. The impact of water quality (decreased chloride-to-sulfate mass ratio from 0.9 to 0.3; addition of orthoP; pH increase to 8.3) on lead and copper concentrations was investigated after stagnation (30 min-336 h) in a pipe rig comparing full lead service line (LSL), and two configurations of partial LSLs (Cu-Pb and Pb-Cu). Results show different trends for lead and copper: maximum lead concentrations were reached in 16 h while copper concentrations continued to increase over 336 h. Lead release rates were also the highest in the first 16 h of stagnation and were strongly impacted by water quality and the configuration of PLSLR (Cu-Pb vs Pb-Cu). Increasing the sampling flow rate from 5 to 15 LPM drastically increased the particulate lead release (78-fold) in Pb-Cu configurations; this effect was however not observed in 100% Pb or Cu-Pb configurations. High velocity flushing prior to 16 h stagnation decreased total Pb release by a factor of 12-fold for Cu-Pb, 1.6-fold for Pb-Cu and 2.0-fold for 100% Pb. Results support the definition of sampling protocols targeted for the detection of lead and copper sources and the proscription of flushing prior to sampling.

Persistent corneal fibrosis after explantation of a small-aperture corneal inlay.

The KAMRA small-aperture corneal inlay can compensate for presbyopia. A small number of complications have been reported, including glare, halos, decentration, iron deposition, compromised distance and night vision, infectious keratitis and reversal corneal haze. We describe a case of corneal fibrosis after small-aperture corneal inlay implantation and its persistence after late explantation. The postoperative period was uneventful, with good uncorrected near and distance visual acuities. Six years after implantation, the patient reported vision loss in the left eye. A slitlamp evaluation and optical coherence tomography showed stromal opacity and a stromal hyperreflective signal at the level of the small-aperture corneal inlay. The corneal inlay was removed, but persistent decreased visual acuity and fibrosis were observed even 8 months after explantation and did not respond to steroids. Long-term monitoring with multimodal imaging methods is important to detect late adverse events after small-aperture corneal inlay implantation.

Study of the long-term impacts of treatments on lead release from full and partially replaced harvested lead service lines.

Long-term (155 weeks) Pb concentrations, following partial lead service lines replacements (PLSLR), were measured in a flow through pilot made of harvested lead service lines (LSL) from the distribution system of the City of Montreal. The present study also investigates how release of Pb from full and partial LSLs is influenced by: pipe diameter, decrease in chloride-to-sulfate mass ratio (CSMR) from 0.9 to 0.3, addition of orthophosphate (1 mg P/L), and increase in pH to 8.3. Pb concentrations were measured after 16 h of stagnation and under flow conditions. In this study, Pb concentrations did not decrease, in the long term, after partial LSL replacement. Moreover, the most effective corrosion control treatment in full LSLs was the addition of orthoP. In contrast, the decrease of the CSMR best reduced lead release from partial LSLs. The impact of pipe configuration therefore influenced the effectiveness of corrosion control treatments. It is noteworthy that the increase in Pb concentrations following PLSLR were attributed to particulate Pb release from the galvanic section of the pipe. The occurrence of galvanic corrosion, caused by the connection between Pb and copper pipes, adds a new source of Pb in the partial LSL. At least, this new source of lead has to be offset by the removal of a long enough section of LSL during PLSLR. Full LSL replacements may be warranted to minimize the exposure of consumers to elevated Pb levels caused by galvanic corrosion in LSLs.

Contribution of Fourier-domain optical coherence tomography to the diagnosis of keratoconus progression.

PURPOSE: To determine the anatomic criteria for diagnosing keratoconus progression by corneal optical coherence tomography (OCT). SETTING: Quinze-Vingts National Ophthalmology Hospital, Paris, France. DESIGN: Prospective case series. METHODS: Scanning-slit corneal topography (Orbscan II) and Fourier-domain corneal OCT (RTVue) were performed in eyes with mild to moderate keratoconus (progressive or nonprogressive [stable] ectasia) at each examination to assess the keratoconus. Disease progression was defined as an increase of at least 1.0 diopter (D) in the steepest keratometry (K) measurement over 6 months. RESULTS: Of the 134 eyes of 134 patients with mild to moderate keratoconus, 98 had had progressive ectasia and 36 nonprogressive ectasia. The mean maximum K increased significantly in the progressive group (2.1 D ± 1.2 [SD], P < .0001) and remained constant in the stable group (-0.03 ± 0.39 D, P = .31). The mean thinnest corneal thickness increased significantly in the progressive group (-7.98 ± 9.3 µm, P < .0001) and remained constant in the stable group (-0.52 ± 4.21 µm, P = .22). The change in maximum K was significantly correlated with changes in the thinnest corneal thickness (r = -0.61, P < .0001). A cutoff value of -5 µm for the change in thinnest corneal thickness was identified on receiver operating characteristic curves as a threshold separating cases of progressive and stable keratoconus (area under the curve, 0.79; sensitivity, 68%; specificity, 89%). CONCLUSIONS: Topographic data partly reflected the structural changes occurring during the progression of corneal ectasia. Based on the pachymetric parameters provided by OCT, corneal and epithelial thinning was correlated with corneal deformation. The use of corneal OCT might therefore improve the diagnostic sensitivity for keratoconus progression.

Genetic Analysis of the Organization, Development, and Plasticity of Corneal Innervation in Mice.

The cornea has the densest sensory innervation of the body, originating primarily from neurons in the trigeminal ganglion. The basic principles of cornea nerve patterning have been established many years ago using classic neuroanatomical methods, such as immunocytochemistry and electrophysiology. Our understanding of the morphology and distribution of the sensory nerves in the skin has considerably progressed over the past few years through the generation and analysis of a variety of genetically modified mouse lines. Surprisingly, these lines were not used to study corneal axons. Here, we have screened a collection of transgenic and knockin mice (of both sexes) to select lines allowing the visualization and genetic manipulation of corneal nerves. We identified multiple lines, including some in which different types of corneal axons can be simultaneously observed with fluorescent proteins expressed in a combinatorial manner. We also provide the first description of the morphology and arborization of single corneal axons and identify three main types of branching pattern. We applied this genetic strategy to the analysis of corneal nerve development and plasticity. We provide direct evidence for a progressive reduction of the density of corneal innervation during aging. We also show that the semaphorin receptor neuropilin-1 acts cell-autonomously to control the development of corneal axons and that early axon guidance defects have long-term consequences on corneal innervation.SIGNIFICANCE STATEMENT We have screened a collection of transgenic and knockin mice and identify lines allowing the visualization and genetic manipulation of corneal nerves. We provide the first description of the arborization pattern of single corneal axons. We also present applications of this genetic strategy to the analysis of corneal nerve development and remodeling during aging.

Early Epithelial Remodeling After Standard and Iontophoresis-Assisted Corneal Cross-linking as Evaluated by Spectral-Domain Optical Coherence Tomography.

PURPOSE: To evaluate and compare epithelial remodeling after standard corneal cross-linking (S-CXL) and iontophoresis-assisted CXL (I-CXL) in eyes with keratoconus by anterior segment optical coherence tomography (AS-OCT). METHODS: In this prospective, observational study, AS-OCT and corneal topography were performed before and 1, 3, and 6 months after surgery. Corneal pachymetry was performed and epithelial and stromal thicknesses (central and 16 points on the 6-mm central zone) and the maximum simulated keratometry value (Kmax) were measured. RESULTS: Two groups of 30 patients (60 eyes total) with progressive keratoconus underwent S-CXL or I-CXL. Before surgery, both groups of patients presented with an irregular epithelial thickness profile. At 6 months postoperatively, localized corneal epithelial thinning was observed in the superior (P = .026), inferior (P = .034), inferonasal (P = .024), and nasal (P = .035) areas at 3 mm and in the superior (P = .039), nasal (P = .043), and inferior (P = .01) areas at 6 mm in the SCXL group. Localized corneal epithelial thinning was observed at 3 (P = .04) and 6 (P = .01) mm in the inferior area in the I-CXL group. No significant stromal changes were observed for either group. Kmax was stable in both groups at 6 months. CONCLUSIONS: Significant epithelial remodeling occurs after S-CXL, resulting in a thinner, more regular thickness profile than after I-CXL. Epithelial thickness profile measurements after I-CXL could be used as an adjunctive follow-up tool for monitoring the efficacy of CXL in progressive keratoconus. [J Refract Surg. 2018;34(8):551-558.].

Lead Levels at the Tap and Consumer Exposure from Legacy and Recent Lead Service Line Replacements in Six Utilities.

Profile, regulatory, and investigative sampling were completed in six utilities to study the impact of partial and full lead service line replacements (LSLRs) on water lead levels (WLLs) and consumer's exposure. As compared to households with no replacement, lead release after partial LSLR (PLSLR) was generally greater in the short term (3-50 days), and comparable or lower in the medium (<2 years) and long-term (>2 years). This was mainly explained by insufficient time elapsed to stabilize scales after disturbances to the service line. One utility showed sustained lead release over 18 months after PLSLR. Moreover, the reduction in WLLs was small when analyzing results for the same households. As a comparison, full LSLR decreased WLLs drastically and immediately. The occurrence of low (0-5 µg/L) to high (≥50 µg/L) WLLs in the profiles varied between households and reflected the variability of exposure among households in the same system. Using this probability of occurrence, the distribution of WLLs of exposure was estimated for households with or without a PLSLR, and used to model young children blood lead levels (BLLs) for both groups of households. The range of modeled BLLs decreased slightly for households with PLSLR, but still overlapped the range estimated for households with no replacement. This analysis suggests that, in a system, PLSLRs do not reduce young children blood lead levels except in a fraction of households.

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.

Integrase-Mediated Recombination of the bel-1 Gene Cassette Encoding the Extended-Spectrum ß-Lactamase BEL-1.

Integrons are genetic elements that can acquire and rearrange gene cassettes. The blaBEL-1 gene encodes an extended-spectrum ß-lactamase, BEL-1, that is present at the second position of the variable region of class 1 integrons identified in Pseudomonas aeruginosa The mobility of the bel-1 gene cassette was analyzed under physiological conditions and with the integrase gene being overexpressed. Cassette mobility in Escherichia coli was detected by excision/integration into the recipient integron In3 on the conjugative plasmid R388 with the overproduced integrase. Despite several antibiotic pressures, the bel-1 cassette remained at the second position in the integron, highlighting its stability in P. aeruginosa Overexpression of the integrase gene in E. coli induced bel-1 cassette recombination. However, cassettes containing two genes (blaBEL-1 and smr2 or blaBEL-1 and aacA4) were excised, suggesting that the bel-1 cassette attC site was defective. We show that bel-1 is a stable gene cassette under physiological growth conditions, irrespective of the selective antibiotic pressure, that may be mobilized upon overexpression of the integrase gene.

Corneal Neurotization With a Great Auricular Nerve Graft: Effective Reinnervation Demonstrated by In Vivo Confocal Microscopy.

PURPOSE: We describe the first case of minimally invasive corneal neurotization with the great auricular nerve (GAN) to treat unilateral neurotrophic keratopathy. We assessed corneal sensation and reinnervation by esthesiometry and confocal microscopy over 12 months of follow-up, and we provide a detailed description of the surgical technique. METHODS: Corneal neurotization was successfully achieved with the ipsilateral GAN in a 58-year-old woman. Cochet-Bonnet esthesiometry and in vivo confocal microscopy were performed before and after corneal neurotization, to monitor the recovery of corneal sensation and corneal reinnervation by subbasal nerve fibers. RESULTS: Neurotrophic keratopathy was a complication of the surgical treatment of meningioma. Before surgery, the patient had no corneal sensation or corneal innervation. Six months after surgery, confocal microscopy confirmed regrowth of a large number of nerve fibers in the subepithelial space of the cornea. Nine months after surgery, a central esthesiometry score of 10-mm was attained. CONCLUSIONS: Corneal neurotization leads to reinnervation of the cornea and recovery of ocular sensation in adults. The GAN is suitable for use in corneal neurotization because of its anatomical proximity and the low level of associated morbidity. Confocal microscopy demonstrated the occurrence of corneal reinnervation, which preceded the recovery of corneal sensation.

Short- and Long-Term Lead Release after Partial Lead Service Line Replacements in a Metropolitan Water Distribution System.

Thirty-three households were monitored in a full-scale water distribution system, to investigate the impact of recent (<2 yr) or old partial lead service line replacements (PLSLRs). Total and particulate lead concentrations were measured using repeat sampling over a period of 1-20 months. Point-of-entry filters were installed to capture sporadic release of particulate lead from the lead service lines (LSLs). Mean concentrations increased immediately after PLSLRs and erratic particulate lead spikes were observed over the 18 month post-PLSLR monitoring period. The mass of lead released during this time frame indicates the occurrence of galvanic corrosion and scale destabilization. System-wide, lead concentrations were however lower in households with PLSLRs as compared to those with no replacement, especially for old PLSLRs. Nonetheless, 61% of PLSLR samples still exceeded 10 µg/L, reflecting the importance of implementing full LSL replacement and efficient risk communication. Acute concentrations measured immediately after PLSLRs demonstrate the need for appropriate flushing procedures to prevent lead poisoning.

New parameters in assessment of human donor corneal stroma.

PURPOSE: To provide quantitative parameters for assessment of human donor corneal stroma by imaging stromal features of diseased and normal human corneas with full-field optical coherence microscopy (FFOCM), using confocal microscopy (CM) and histology as reference techniques. METHODS: Bowman's layer (BL) thickness and keratocyte density were assessed ex vivo in 23 human donor corneas and 27 human pathological corneas (keratoconus and other corneal disorders) with FFOCM, CM and histology. Stromal backscattering was assessed with FFOCM. Additionally, 10 normal human corneas were assessed in vivo with CM. RESULTS: In FFOCM, the logarithm of the normalized stromal reflectivity was a linear function of stromal depth (R2  = 0.95) in human donor corneas. Compared with keratoconus corneas, human donor corneas featured higher BL thickness (p = 0.0014) with lower coefficient of variation (BL-COV; p = 0.0002), and linear logarithmic stromal reflectivity with depth (higher R2 , p = 0.0001). Compared with other corneal disorders, human donor corneas featured lower BL-COV (p = 0.012) and higher R2 (p = 0.0001). Using the 95% confidence limits of the human donor cornea group, BL thickness < 6.5 µm (sensitivity, 57%; specificity, 100%), BL-COV > 18.6% (79%; 100%) and R2  < 0.94 (93%; 71%) were revealed as indictors of abnormal cornea. In CM, keratocyte density decreased with stromal depth (r = -0.56). The mean overall keratocyte density (cells/mm2 ) was 205 in human donor corneas, 244 in keratoconus, 176 in other corneal disorders and 386 in normal corneas. CONCLUSION: Full-field optical coherence microscopy (FFOCM) provides precise and reliable parameters for non-invasive assessment of human donor corneal stroma during storage, enabling detection of stromal disorders that could impair the results of keratoplasty.

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.