Corneal densitometry changes after femtosecond laser-assisted intracorneal ring segments implantation in keratoconus.

Background: Intrastromal corneal ring segments are commonly implanted in the corneas of eyes with mild-to-moderate keratoconus; however, changes in corneal densitometry (CD) after implantation are a matter of debate in the current literature. We evaluated the changes in CD 1 and 3 months after femtosecond laser-assisted Keraring implantation. Methods: This retrospective, non-comparative, multicenter, case series study included patients with keratoconus who underwent femtosecond laser-assisted implantation of double segments with 90° and 160° arc lengths or two 160° arc length Keraring segments. Demographic and baseline clinical ophthalmic data were recorded. Corneal topography and tomography data acquired using a Pentacam HR Scheimpflug tomography system (Pentacam High Resolution; Oculus, Wetzlar, Germany) with a best-fit sphere were used as a reference surface. Using the Pentacam HR, CD measurements were acquired over a corneal area of 12 mm in total and at four concentric zones (0-2, 2-6, 6-10, and 10-12 mm) of three corneal stromal depths: 120 µm of the anterior corneal stromal layer, 60 µm of the posterior corneal stromal layer, and the central layer of stroma lying between these two layers. Results: We included 40 eyes of 40 patients, including 8 (20%) male and 32 (80%) female individuals, with a mean (standard deviation) age of 21.0 (6.4) years. We observed a significant improvement in the topographic values of steep keratometry (K), flat K, maximum K, and corneal astigmatism (all P < 0.05), but not in the mean K, thinnest corneal pachymetry, corneal thickness at the apex, back elevation, or front elevation (all P > 0.05). The mean total anterior, central, and posterior CD differed significantly among the time points, with a significant increase from the preoperative to the 1-month and 3-month postoperative visits (all P < 0.05) and no difference between those of the 1-month and 3-month postoperative visits (all P > 0.05). The mean CD for the anterior layer in the central, paracentral, and mid-peripheral zones, and the central layer in all four zones, differed significantly among time points, with a significant increase from the preoperative to the 1-month and 3-month postoperative visits (all P < 0.05), which remained unchanged from the 1-month to the 3-month postoperative visit (all P < 0.05), except for the central 2-6-mm zone, which decreased significantly from the 1-month to the 3-month postoperative visit (P < 0.001). The CD of the central 10-12-mm zone did not differ significantly in each pairwise comparison (all P > 0.05). In contrast, CD for the posterior layer in the paracentral zone decreased significantly from the preoperative to the 1-month and 3-month postoperative visits but increased, to a lesser extent, from the 1-month to the 3-month postoperative visit (all P < 0.05). Conclusions: Femtosecond laser-assisted Keraring implantation significantly changes CD, with improvement in most topography parameters. Further longitudinal studies with larger sample sizes are required to verify these preliminary findings.

Application of a Revised Tissue Saving Protocol for Combined Topography-Guided Photorefractive Keratectomy and Cross-Linking in a Cohort Having Pellucid Marginal Degeneration.

Purpose: To evaluate the efficiency, safety, and stability of a revised tissue-saving treatment protocol in a cohort having pellucid marginal degeneration (PMD). Methods: A retrospective cohort study was conducted on patients with PMD and no previous treatments. A revised protocol of topo-guided photorefractive keratectomy to be followed by customized phototherapeutic keratectomy and then corneal crosslinking was evaluated by comparing the pre and postoperative outcomes regarding visual (subjective refraction) and topographic (using data from Sirius CSO topography software) outcomes. Results: There were both statistically significant and clinically relevant improvements in the postoperative parameters, where each of the unaided and corrected visual acuity, spherical equivalent, refractive cylinder, K readings, topographic cylinder, inferior minus superior difference at the 2- and 4- mm diameters, coma aberration, and higher order aberrations were significantly better postoperatively (all p values were less than 0.01, except for maximum k readings where the p-value was 0.017). The safety and efficacy indices for the surgical procedure were remarkably high (1.53 ± 0.70 and 0.90 ± 0.32, respectively). Conclusion: Our proposed tissue-saving protocol (which showed satisfactory results in keratoconus cases according to a previously published article by our research team) has proven its successful outcomes (both topographically and visually) in cases of PMD, which is a rare ectatic entity with guarded prognosis using the available conventional ectasia treatment modalities.

A sequential approach to the management of an advanced case of pellucid marginal degeneration.

Purpose: We report a sequential approach in the management of a case with advanced pellucid marginal degeneration (PMD). The management was tailored based on the patient's corneal topography and degree of corneal astigmatism. Full thickness corneal transplants in cases of PMD carry a prolonged rehabilitation period and the risk of graft failure.This case consisted of lamellar wedge resection followed by wavefront guided transepithelial photorefractive keratectomy (wTPRK) combined with accelerated corneal crosslinking (aCXL) in preparation for a cataract extraction with intraocular lens. Observation: A 68-year-old gentleman with advanced PMD underwent phacoemulsification with toric intraocular lens (T-IOL) for the right eye and a lamellar wedge resection, followed by wTPRK combined with aCXL for the contralateral eye. The left eye underwent a sequential approach to regularize the cornea, minimize the higher order aberrations (HoA) and degree of corneal astigmatism. Effective visual rehabilitation was achieved with significant visual improvement. Conclusion and importance: Although advanced PMD may have limited options for visual rehabilitation, a sequential stepwise approach may be considered in such cases, permitting a better quality with less invasive options.

Corneal Cross-Linking in Pellucid Marginal Degeneration: Evaluation after Five Years.

Purpose: To evaluate the long-term outcome of corneal cross-linking (CXL) for pellucid marginal degeneration (PMD). Methods: In a retrospective study, forty eyes of forty patients were enrolled. All subjects had undergone CXL for PMD at least 5 years before the assessments. Visual acuity, refraction, and topography data were compared to their respective values before CXL. Results: The comparison between mean preoperative logMAR uncorrected visual acuity and 5-year postoperative evaluation revealed no significant change (1.20 ± 0.65 and 1.17 ± 0.64, P > 0.05). No statistically significant difference was noted comparing preoperative mean logMAR best-corrected visual acuity (BCVA) and postoperative mean logMAR BCVA (0.24 ± 0.19 and 0.22 ± 0.20, P > 0.05). We did not find any significant difference between pre- and postoperative spherical equivalent and spherical refractive errors (P = 0.419 and P = 0.396, respectively). Regarding the BCVA Snellen lines, 23 eyes had no significant change in pre- and postoperative examinations, 11 eyes had improvement, and 6 subjects showed worsening defined as significant when two or more lines change. The spherical equivalent refractive error improved in 4 subjects, was stable in 25, and worsened in 11 subjects, while a 0.5 diopter or more myopic change was considered significant. Furthermore, regarding steep keratometry values, 25 subjects were stable, 7 had improvements, and 8 worsened. Conclusion: CXL appears to be a safe and effective procedure to halt the progression of PMD.

Demographic, clinical and tomographic characteristics of pellucid marginal degeneration patients in South Egyptian population.

PURPOSE: To retrospectively evaluate the demographic, clinical, and tomographic characteristics of pellucid marginal degeneration (PMD) patients in South Egypt. METHODS: This study was retrospective cross-sectional, including all patients who attended and sought refractive surgery at Sohag Center for Corneal and Refractive Surgeries, Sohag, South Egypt, between October 2016 and October 2020, and had a diagnosis of PMD. It included cases of PMD at different stages. Cases with PMD were diagnosed by the two authors (experienced in corneal refractive surgery), combining both slit-lamp biomicroscopy findings and corneal tomography. RESULTS: Out of the 2534 patients attending the Sohag Center for Corneal and Refractive Surgeries (between October 2016 and May 2020) seeking correction of their refractive errors, 24 patients were found to fit in the diagnosis of PMD. Forty-three eyes of the 24 patients were diagnosed with PMD. The topographic patterns ranged from horizontal bow tie (against the rule astigmatism) being the least presenting, followed by crab claw, then butterfly pattern. CONCLUSION: PMD is a separate entity of the ectatic corneal spectrum that can easily be misinterpreted as Keratoconus. Topographic and tomographic patterns cannot solely diagnose PMD as they should be enforced by slit-lamp findings.

Outcomes of a Single-Segment Intrastromal Corneal Ring in Early Keratoconus and Early Pellucid Marginal Degeneration.

PURPOSE: To determine the effect of a single-segment intrastromal corneal ring segment (ICRS; Intacs SK) on early keratoconus (KCN) and pellucid marginal degeneration (PMD). METHODS: It is a prospective interventional study. One hundred twenty-four eyes (99 patients) with KCN and 36 eyes (26 patients) with PMD at early stage (the maximum keratometric reading less than 55 diopters) were included to ICRS implantation using femtosecond laser at a tertiary university-based hospital and a private outpatient center. The uncorrected distance and spectacle-corrected visual acuity (UDVA and SCDVA), manifest spherical and cylindrical refractions, and keratometry indices were measured preoperatively and postoperatively, 1 week, 2 and 6 months. RESULTS: One week after surgery, significant improvements were observed in UDVA, SCDVA, cylinder and keratometry readings of both KCN and PMD groups (all P < 0.05) with no significant changes afterward. No significant change occurred in the sphere refraction of PMD group (P = 0.10) in contrast to KCN group (P < 0.001). Corneal irregularity of KCN group in central 3 and 5 mm zones increased at 1 week (both P < 0.001) and then started to decrease up to 6 months. However, the corneal irregularity of PMD group had significant reduction only at 1 week in 5-mm zone (P = 0.02) and 2 months in 3-mm zone (P = 0.01) postoperatively. The final efficacy indexes were 1.44 ± 0.71 and 0.87 ± 0.40 in KCN and PMD groups, respectively. CONCLUSION: Visual acuity, refractive errors and keratometry values have been improved after one-segment Intacs SK implantation in early KCN and PMD patients.

Different mRNA expression patterns in keratoglobus and pellucid marginal degeneration keratocytes.

PURPOSE: Alike keratoconus (KC), keratoglobus (KG) and pellucid marginal degeneration (PMD) belong to ectatic corneal diseases. While there are numerous studies on keratoconus pathophysiology, there is no exact knowledge on genetic and pathophysiological background of KG and PMD, so far. It is not yet clarified, whether KG and PMD are independent clinical entities or represent different stages of the same disease. Our purpose was to investigate key parameters concerning collagen synthesis, intracellular LOX expression and inflammation in corneal stromal cells of KG and PMD subjects, in vitro. METHODS: Normal human keratocytes of corneas from the LIONS Cornea Bank Saar-Lor-Lux, Trier/Westpfalz and human keratocytes of KG and PMD patients were isolated and cultured as keratocytes. To examine Collagen I and V (Col I, Col V), heat shock protein 47 (Hsp47), Lysyl Oxidase (LOX), nuclear factor kappa B (NF-κB) mRNA and protein expression in all cell types, quantitative PCR and Western blot analysis has been performed. RESULTS: Col5A1 mRNA expression was significantly lower in KG and PMD keratocytes and LOX mRNA expression was significantly higher in KG-keratocytes, compared to controls. Col1A1, Hsp47 and NF-κB mRNA expression and the analyzed protein expressions did not differ from controls, in KG or PMD. CONCLUSIONS: Col5A1 mRNA expression is decreased in KG and PMD and LOX mRNA expression is increased in KG. Therefore, the pathophysiology of KG and PMD differs from KC and these seem to be from KC independent entities. The explanation of the peripheral corneal thinning in KG and PMD must be investigated in further studies.

[Intracorneal ring segments in keratoconus management]. / Les anneaux intra-cornéens dans la prise en charge du kératocône.

Intracorneal ring segments (ICRS), used in the management of keratoconus since the 2000s, have enjoyed significant technological development. Various types of ICRS exist, whose arc length, thickness, and diameter can be chosen according to the desired effect on the spherical equivalent, keratometry and asphericity. Individualized implantation strategies, based on each patient's topographic and tomographic pattern, are constantly evolving. The surgical procedure is standardized, and complications remain very rare. Combined procedures (corneal collagen cross-linking and refractive photokeratectomy±topo-guided, phakic and pseudophakic intraocular lenses) are increasingly used and require a good knowledge of the effect of ICRS alone on the keratoconic cornea. The objective of this review is to summarize clinical practices used in the visual rehabilitation of keratoconic patients using the ICRS+- combined procedures.

Toric intraocular lens implantation - atypical cases.

Objective: To describe the results of toric intraocular lens (IOL) implantation in three atypical cases (four eyes) with cataract and corneal astigmatism: one with bilateral keratoconus, one with pellucid marginal degeneration and one with buphthalmos due to congenital glaucoma. Methods: Three patients (four eyes) with corneal astigmatism (one with bilateral keratoconus, one with pellucid marginal degeneration and one with buphthalmos due to congenital glaucoma) underwent cataract surgery by standard phacoemulsification and the implantation of toric IOLs in the capsular bag. The presence of corneal astigmatism was identified by automated keratometry and confirmed by Scheimpflug-based corneal tomography. The toric IOL implanted in all cases was a single-piece AcrySof Toric IOL (Alcon Laboratories, Inc.). Postoperative visual acuity, the reduction in the refractive astigmatism, the spherical equivalent (SE) and the rotational stability of the toric IOL were recorded for all the patients. Results: Visual acuity increased and the refractive astigmatism decreased in all cases. In Case 1, the right eye achieved a postoperative uncorrected visual acuity (UCVA) of 20/ 20, a decrease in the refractive astigmatism from -3 DCyl to -0.75 DCyl and a spherical equivalent (SE) of -0.25. The left eye presented with a best-corrected visual acuity (BCVA) of 20/ 20, a decrease in the refractive astigmatism from -1.50 DCyl to -1.25 DCyl and a SE of -0.25. In Case 2, the postoperative UCVA was 20/ 20, with a decrease in the refractive astigmatism from -5.5 DCyl to -1 DCyl and a SE for the right eye of 0.00 D. In Case 3, the postoperative BCVA was 20/ 20, with a decrease in the refractive astigmatism from -4.75 DCyl to -1.50 DCyl and a SE of +1.25. No misalignment of the axis of the toric IOL was observed in any patient at subsequent follow-ups. The postoperative visual acuity was satisfactory for all the patients. Conclusions: Toric intraocular lenses can be an effective option for implantation in patients with cataract and corneal astigmatism in atypical situations such as mild to moderate keratoconus, pellucid marginal degeneration and buphthalmos due to congenital glaucoma. Predicting the refractive outcome is difficult in atypical cases and the surgeon should have accuracy and consistency in the preoperative measurements, for achieving satisfactory postoperative results.

Toll-like receptors as diagnostic targets in pellucid marginal degeneration.

The main purpose of this study is to evaluate the diagnostic role of Toll-like receptors 2 (TLR2) and 4 (TLR4) expression in corneal and conjunctival epithelial cells of eyes with pellucid marginal degeneration (PMD) compared to keratoconus patients (KC) and control subjects. A prospective case-control study in 29 PMD eyes, 109 KC eyes and 72 healthy eyes was done. All participants were subjected to a clinical, topographic, aberrometric and tomographic exam with extraction of corneal and conjunctival epithelial cells through scraping. The TLR2 and TLR4 expression was measured with flow cytometry. Receiver operating characteristic (ROC) curve analysis was used to determine the most appropriate cutoff point for predicting the risk of PMD and KC. Correlations between TLR2/TLR4 expression and the severity of PMD/KC were evaluated. A TLRs follow-up review was made 19 ± 4 months after to the first review. As result, mean expression of TLR2 and TLR4 in both corneal and conjunctival epithelial cells was significantly higher in eyes with corneal ectasia (PMD and KC) than in control eyes (all p < 0.05). Conjunctival TLR4 expression showed the highest capacity to diagnose the existence of PMD (odd ratio 42.84; 95% confidence interval:6.20-296.20; p < 0.0001) after adjusting by eye rubbing and steeper corneal meridian. Moreover, we found an association between the TLR2/TLR4 overexpression with the severity of the PMD and KC measured by corneal topographic, aberrometric and tomographic quantitative parameters (all p < 0.05). Differences on TLR2/TLR4 expression between study groups were maintained during the follow-up period. In conclusion, the TLR2/TLR4 overexpression in corneal and conjunctival epithelial cells of PMD and KC patients compared to healthy control subjects have demonstrated their role as diagnostic target in both corneal ectatic disorders.

A Teenager with Vernal Keratoconjunctivitis and Pellucid Marginal Degeneration, Presenting with Exotropia.

BACKGROUND: Vernal keratoconjunctivitis (VKC), an allergic disease, has a known association with ectatic disorders of the cornea. Pellucid marginal degeneration (PMD) is a bilateral, asymmetrical, ectatic disorder of the cornea characterized by inferior corneal thinning. We report a case of sensory exotropia due to PMD in association with VKC. CASE DETAILS: A 19-year old boy with a history of VKC presented with exotropia of the right eye of 3 years' duration. His unaided vision in his right eye was 1/60 and in his left eye it was 6/36. On examination, both eyes had high against the rule astigmatism, which was more in the right eye. There was exotropia of 15º (40 prism diopter base in) in the right eye with suppression (Worth four dot test). Corneal examination in both eyes showed inferior band thinning, 2 mm above the inferior limbus, extending from 4 to 8 clock hours, with bulging of the cornea just above the thinning. The clinical features were suggestive of PMD, which was supported by his corneal scans - Atlas, Pentacam, and Optovue. Although he was undergoing treatment for VKC, the onset of PMD and decrease in vision went unnoticed. The asymmetric error which was not corrected during the sensitive period of visual development led to sensory exotropia. CONCLUSION: A child with VKC should undergo regular refraction so as not to miss any ectatic changes occurring in the cornea. A delay in diagnosing corneal ectasia may negate the possibility of collagen cross-linking which prevents progression of ectasia. If visual rehabilitation is delayed beyond the age of visual maturation, it can lead to strabismus, suppression, and loss of binocular function.

Late progressive corneal flattening, haze and visual loss after eccentric crosslinking for Pellucid marginal degeneration.

PURPOSE: Pellucid marginal degeneration (PMD) is a rare disease that is often mistaken for keratoconus but can similarly be treated with corneal collagen crosslinking (CXL). We report a case followed though 6 years of progressive irregular corneal flattening and thinning in both eyes (OU) after eccentric CXL for PMD. OBSERVATION: A 46-year-old man with bilateral PMD and corrected distance visual acuity (CDVA) of 20/20 (-2.00x80) in the right eye (OD) and 20/30 (+3.50-5.25x105) in the left eye (OS) underwent conventional 9 mm eccentric CXL in OU and intrastromal corneal ring implantation in the OS. An uneventful first year postoperative follow-up showed stabilization of the ectasia. In subsequent years, progressive inferior flattening was observed with decreased CDVA, corneal thinning and worsening of the haze. At the last follow-up, his CDVA was 20/40 (+5.00-2.00x55) OD and 20/60 (+6.00-1.50x80) OS. CONCLUSION AND IMPORTANCE: The current report highlights the notion that mid- and long-term evaluations of customized crosslinking techniques may reveal progressive flattening and corneal irregularity.

[Efficacy of visual rehabilitation of patients with pellucid marginal degeneration fitted with SPOT® scleral contact lenses]. / Efficacité de la réhabilitation visuelle de patients atteints de dégénérescence marginale pellucide adaptés en lentilles sclérales SPOT.

PURPOSE: To assess visual improvement in patients with pellucid marginal degeneration (PMD) after fitting with SPOT® scleral contact lenses (Scleral Protection & Ocular Treatment, Laboratoires d'Appareillage Oculaire, Amphion-Les-Bains, France). METHODS: We report a case series of 5 patients with PMD and unsatisfactory refractive correction managed at Clermont-Ferrand university hospital from January to December 2018 fitted with customized SPOT scleral lenses. We assessed the best-corrected visual acuity (BVCA) before and after fitting with SPOT, keratometric data and tolerability of the scleral lenses. RESULTS: Nine eyes of 5 patients aged 51.8±8.47 years were fitted. The BVCA was significantly improved from 0.51 logMAR (±0.39) to 0.04 logMAR (±0.07) (P<0.001). Sixty-six percent of the patients recovered optimal BVCA. No serious adverse event was reported. The presence of whitish deposits and an inordinate amount of manipulation required were the main disadvantages of the lenses. Nevertheless, all the patients considered them to be comfortable. CONCLUSION: Fitting PMD patients who have failed conventional optical devices with SPOT scleral lenses significantly improves BCVA, without serious adverse events, allowing surgery to be deferred even when it appears to be unavoidable.

Efficacy of visual rehabilitation of patients with pellucid marginal degeneration fitted with SPOT® scleral contact lenses.

PURPOSE: To assess visual improvement in patients with pellucid marginal degeneration (PMD) after fitting with SPOT® scleral contact lenses (Scleral Protection & Ocular Treatment, Laboratoires d'Appareillage Oculaire, Amphion-Les-Bains, France). METHODS: We report a case series of 5 patients with PMD and unsatisfactory refractive correction managed at Clermont-Ferrand university hospital from January to December 2018 fitted with customized SPOT scleral lenses. We assessed the best-corrected visual acuity (BCVA) before and after fitting with SPOT, keratometric data and tolerability of the scleral lenses. RESULTS: Nine eyes of 5 patients aged 51.8±8.47 years were fitted. The BCVA was significantly improved from 0.51 logMAR (±0.39) to 0.04 logMAR (±0.07) (P<0.001). Sixty-six percent of the patients recovered optimal BCVA. No serious adverse event was reported. The presence of whitish deposits and an inordinate amount of manipulation required were the main disadvantages of the lenses. Nevertheless, all the patients considered them to be comfortable. CONCLUSION: Fitting PMD patients who have failed conventional optical devices with SPOT scleral lenses significantly improves BCVA, without serious adverse events, allowing surgery to be deferred even when it appears to be unavoidable.

Prevalencia de pacientes con queratocono en la Clínica Barraquer en Bogotá, Colombia / Prevalence of keratoconus patients at the Barraquer Clinic in Bogotá, Colombia

Introducción: Queratocono es un término clínico amplio, que describe un estado de la córnea derivado de su adelgazamiento focal y protrusión secundaria central, paracentral y/o periférica. Los reportes epidemiológicos globales revelan un amplio rango en cifras de prevalencia e incidencia que se podría explicar por las diferencias geográficas, factores de riesgo, tipo de población, métodos y criterios diagnósticos utilizados. En Colombia no hay estudios epidemiológicos que evalúen esta enfermedad de manera integral por lo que su frecuencia aún no ha podido ser determinada. Objetivo: identificar la prevalencia de Queratocono y Degeneración Marginal Pelucida (DMP) en el centro oftalmológico privado Clínica Barraquer, durante el periodo de tiempo comprendido entre enero de 2014 y enero de 2019. Diseño del estudio: estudio transversal de fuentes secundarias. Método: revisión de los registros médicos electrónicos de todos los pacientes que consultaron por primera vez; posteriormente, se filtraron por el diagnóstico de Ectasia Corneal y/o Queratocono. Cada una de las historias clínicas fue analizada por un oftalmólogo teniendo en cuenta los diagnósticos preestablecidos. Resultados: del grupo de 91.426 pacientes, 2.647 tenían Queratocono o DMP. Se estableció una prevalencia de Queratocono y DMP del 2.84%. La edad promedio al momento del diagnóstico fue de 29.7±12 años. El 42.8% eran mujeres y el 57.2% hombres. Conclusión: la ectasias corneales de tipo Queratocono y DMP, son enfermedades con una prevalencia significativa en la población colombiana evaluada en la clínica Barraquer; consideramos se requiere de programas de tamizaje visual para su detección y tratamiento oportunos.

Background: Keratoconus is a wide clinical term used to describe a corneal disease characterized by thinning and secondary central, paracentral or peripheral protrusion of the cornea. The global epidemiological reports reveal a wide range of prevalence and incidence, that may be explained by geographical differences, risk factors, kind of population, and methods and diagnostic criteria employed. There are no epidemiological studies to evaluate globally this disease in Colombia, therefore, its frequency has not been determined yet. Objective: to identify the prevalence of Keratoconus and Pellucid Marginal Degeneration (PMD) from January 2014 to January 2019 at the private ophthalmological center Clínica Barraquer. Study Design: cross-sectional study using secondary data. Method: a review of the electronic medical records of all patients who consulted for the first time was performed, and then, filtered by the initial diagnosis of Corneal Ectasia or Keratoconus. Each one of the medical records was analyzed by an ophthalmologist taking into account a series of pre-established diagnostic criteria. Results: of 91.426 patients, 2.647 had Keratoconus or PMD within the time interval of the study. A prevalence of 2.84% was determined in first time patients. The average age at the time of diagnosis was 29.7±12 years. 42.8% were female patients and 57.2% male patients. Conclusion: Keratoconus and PMD are diseases with significant prevalence in the Colombian population evaluated at the Barraquer clinic, thus, visual screening programs are required for accurate detection and treatment.

Combined Corneal Wedge Resection And Corneal Cross-Linking For Pellucid Marginal Degeneration: A First Report.

BACKGROUND: Advanced pellucid marginal degeneration is a debilitating disease that warrants the use of surgery when the visual acuity is reduced and contact lenses are not tolerated anymore. It is traditionally managed with corneal transplantation, however alternative surgical options exist. Corneal wedge resection allows for good visual rehabilitation without the risks of tissue rejection. However topographical and refractive results are in some instance fluctuating. We present here the use of corneal cross-linking in order to stabilize the parameters on the long term. CASE PRESENTATION: We present here the case of a 53 years old patient with bilateral advanced pellucid marginal degeneration. As he is now intolerant to contact lenses a surgical option is offered to him. In order to avoid using donated tissue through corneal grafting we decide to perform a sectorial lamellar crescentric wedge excision of the thinner inferior part of the cornea involving the pellucid marginal degeneration and suture it. The first eye shows initial good results however after few months regression is observed. The second eye is then treated with the same surgical technique combined with cornea cross-linking. Long-term follow-up shows stabilization and absence of regression in the second eye up to eight months after the surgery. CONCLUSION: Combining corneal cross-linking with corneal wedge resection in the case of advanced pellucid marginal degeneration patients could be a good option in order to stabilize topographical and refractive results and reduces the risk of regression.

Corneal Cross-Linking: An Effective Treatment Option for Pellucid Marginal Degeneration.

Purpose: This is the first review article examining literature specific to the use of corneal cross-linking (CXL) to treat pellucid marginal degeneration (PMD). Results: CXL appears to be an effective treatment that may halt the progression of PMD to stabilize vision. This could postpone or eliminate the need for corneal transplantation in the management of these patients. Furthermore, combining CXL with keratorefractive surgery in a single procedure has been shown to be safe and successful in improving vision in PMD patients. Conclusions: The data reported in literature is limited at this time, consisting mostly of retrospective studies with short term follow up. Further research is needed to evaluate refractive effects of combined CXL and excimer laser procedures.

Yield of Display Modules of Corneal Tomography for Early Diagnosis of Corneal Ectasia.

The thesis deals with comparison of topographic corneal indexes and their importance for the diagnosis of corneal ectatic disease. The corneas with different stages of keratoconus, forme fruste keratoconus, pellucid marginal degeneration, corneal warpage syndrome, and physiological cornea with varying values of regular astigmatism were included in the tested group. The study was conducted in 2015-2018 at the European Eye Clinic Lexum Brno. The study group contained 208 eyes, 111 eyes with keratoconus, 31 eyes with forme fruste keratoconus, 23 eyes with pellucid marginal degeneration, 10 eyes with corneal warpage syndrome and 33 physiological eyes. 19 corneal parameters and indexes were monitored for these ectatic diseases, which were compared with healthy corneas with regular astigmatism. A single-factor ANOVA test, a Student t-test were used for statistical analysis. Pearson's coefficients were used to assess the correlation. In all the observed tomographic parameters a statistically significant difference was found between the physiological and ectatic group of corneas. The parameters with the highest statistical difference were BEThLo, ISV, IHD, D, Rmin. Statistically significant indices were also found between the forme fruste keratoconus and physiological corneas. The best parameters for detecting the subclinical keratoconus were the back elevation at the thinniest point of the cornea (BEThLo), the difference between the thinniest and the central point of cornea (CP-TL), the maximum pachymetic progression index and the Db and D indexes (p 0.6) according to Pearson's correlation coefficient. Statistically significant differences in the KK and PMD groups were found in the index of relative pachymetry, central pachymetry, CKI and Dp. Key words: Pentacam, corneal ectasia, keratoconus, pellucid marginal degeneration, corneal warpage syndrome, forme fruste keratoconus.

Late detachment of Descemet's membrane after penetrating keratoplasty for pellucid marginal degeneration.

PURPOSE: we report a case of late spontaneous large detachment of Descemet's membrane in recurrent pellucid marginal degeneration after penetrating keratoplasty. OBSERVATIONS: a 73-year-old man presented to clinic with spontaneous detachment of his Descemet's membrane 30 years after penetrating keratoplasty for pellucid marginal degeneration. Efforts were made to bubble the membrane back into place without success. The patient then underwent endothelial keratoplasty with successful restoration of cornea clarity. CONCLUSIONS AND IMPORTANCE: this condition may cause diagnostic and treatment dilemmas if not properly identified and managed. In addition this case has information for both the use of scleral contact lens and the success of endothelial keratoplasty in an extremely steep cornea.