Pellucid Marginal Degeneration Research Articles

Dual benefits of scleral lenses in collateral cases of Stevens-Johnson syndrome and Keratoconus-A case series

Scleral lenses (SL) are larger diameter lenses that rest over the scleral, unlike the corneal lenses. These lenses are fitted to not touch the cornea by creating a space that will be filled with sterile isotonic fluid. Indications of SL include corneal ectatic conditions such as keratoconus (KC), pellucid marginal degeneration,and ocular surface disorders such as dry eye (DE), Stevens-Johnson syndrome (SJS), and graft-versus-host disease. Corneal ectasia in SJS has been rarely reported but still exists, which causes severe DE, photophobia, and blurred vision. In such a scenario, SL is an ideal treatment option as they provide constant lubrication to the ocular surface and better visual acuity. This report witnessed the effectiveness of SL in SJS associated with KC – a rare combination.

Scleral lens induced short term corneal changes in eyes with Pellucid Marginal Degeneration

PurposeTo investigate the short-term effect of scleral lens (SL) on corneal curvature and corneal oedema in Pellucid Marginal Degeneration (PMD) eyes. MethodsCorneal anterior, posterior curvature and corneal thickness were measured in 14 eyes of 14 PMD participants with Schiempflug imaging at different corneal diameters and meridians at baseline and after 6 h of SL wear. ResultsThere was a significant flattening (up to 0.26 mm) of the anterior corneal curvature noted in the inferotemporal quadrant (from 210 to 255 degree at 2 mm, 8 mm and 10 mm corneal diameter), inferonasal quadrant (from 285 to 345 degree at 6 mm and 8 mm corneal diameter), and inferiorly at 2 mm and 10 mm corneal diameter (p < 0.05). Similarly, posterior corneal curvature showed statistically significant steepening mostly in inferotemporal quadrants (from 195 to 255 degree from 4 mm to 8 mm corneal diameter) and inferonasally at 2 mm and 4 mm corneal diameter (p < 0.05). A statistically significant increase in the corneal thickness noted in different corneal diameters with corneal oedema ranging from 2.10 % to 4.00 % after 6 h of SL wear. A gradual increase in corneal oedema was noted form centre to periphery. The baseline central fluid reservoir thickness (FRT) was 341.07 ± 139.8 which reduced to 276.71 ± 114.32 µm after 6 h of lens wear. No significant correlation was noted between corneal oedema with different parameters like initial and final FRT, change in anterior and posterior corneal curvature, and lens thickness (p > 0.05). ConclusionsShort-term SL wear induced a clinically acceptable range of corneal oedema. A clinically significant flattening in anterior curvature and minimal steepening in posterior curvature were noted. Practitioners should be careful while measuring corneal parameters in PMD eyes wearing SL, as these alterations can provide false impression of disease progression.

Strategies and Application of Compression Sutures With a Modified Technique for Rapid Resolution of Large (Grade III) Hydrops: A Prospective Interventional Study.

The aim of this study was to describe the strategies and outcomes, with a modified technique, of compression sutures in large acute hydrops. This was a prospective interventional study in 29 eyes of 28 patients who underwent compression sutures using a modified technique. The degree of resolution after surgical intervention was quantified by 3 masked observers, using the slit-lamp photographic documentation and optical coherence tomography. The degree of resolution, best-corrected visual acuity, and complications were analyzed. The mean age was 20.89 (7-46) years. Five patients had pellucid marginal degeneration (pellucid marginal corneal degeneration), 23 had keratoconus, and 1 had posttrauma hydrops. The preoperative visual acuity was hand motions in all eyes. The reduction in edema was 76% on day 1, 91.6% on 6 ± 2 days, 98.6% on 18 ± 3 days from surgical intervention. The baseline pachymetry assessed on optical coherence tomography was beyond measurement in 26 eyes. The mean pachymetry at day 1 was 704 μm (range 480-950) which reduced to 607 (range 422-850) microns at 6 ± 2 days and 518 (range 415-718) microns at 18 ± 3 days postintervention (P < 0.0001). The mean duration between the surgery and complete suture removal was 48 (35-68) days. No suture-related complications were noted. Twenty eyes could attain good visual rehabilitation with glasses/contact lenses (vision could not be assessed in 5 eyes). Penetrating keratoplasty was performed on 1 patient. Compression sutures using the modified technique was safe and effective in the rapid resolution of acute hydrops in keratoconus and pellucid marginal corneal degeneration. No complications were noted, and visual restoration with spectacles and contact lenses was satisfactory.

Altered Corneal Biomechanics According to the Biomechanical E-Staging in Pellucid Marginal Degeneration

Purpose: The purpose of this study was to investigate corneal biomechanics in pellucid marginal degeneration (PMD) compared with healthy controls using Corvis ST (Oculus, Germany) by using the new biomechanical E-staging (based on the Corvis Biomechanical Factor, the linearized Corvis Biomechanical Index) together with tomographic parameters. Methods: Corneal biomechanical and topographic data of 75 eyes of 75 patients with PMD and 75 eyes of 75 age-matched and sex-matched healthy controls were investigated. Topographic parameters (K1, K2, Kmax, central corneal thickness (CCT), and Belin/Ambrósio Deviation Index (BAD-D) were evaluated in dependence of and correlated with the biomechanically defined E-stages. Biomechanical parameters were also recorded for the 2 groups. Results: Patients with PMD showed higher K2, Kmax, BAD-D, and Corvis Biomechanical Factor values and a lower CCT compared with healthy controls (P &lt; 0.001). The E-stage was positively correlated with K1, K2, Kmax, BAD-D, and intraocular pressure difference and negatively correlated with CCT. Stage-dependent analysis revealed a significant increase in K1, K2, Kmax (P &lt; 0.001), and BAD-D (P = 0.041) in stage E3 compared with E0 and a significant decrease in stage E2 in CCT (P = 0.009) compared with E0. Conclusions: This study showed that patients with PMD may have a reduced corneal stiffness compared with healthy controls which worsens with increasing E-stage. Significant changes in topographic parameters were observed at stage E2 for CCT and at stage E3 for K1, K2, Kmax, and BAD-D when compared with stage E0.

Aberration change after scleral lens wear in eyes with pellucid marginal degenerations.

To investigate the impact of scleral lenses (SLs) on higher-order aberrations (HOAs), corrected distance visual acuity (CDVA), and contrast sensitivity (CS) in pellucid marginal degeneration (PMD) eyes. SLs were fitted in 24 eyes diagnosed with PMD. CDVA, CS, and HOAs were measured at baseline and with the lens on the eye. The HOAs were measured using an i-Trace aberrometer. A statistically significant improvement was noted in CDVA (P < 0.001) with BSS lenses (0.05 ± 0.04) compared to baseline (0.42 ± 0.06). Front surface eccentricity 1 (FSE1) lens provided the best CDVA in most of the eyes. The baseline CS of 1.24 ± 0.74 improved to 1.58 ± 0.48 with SL and reported a statistically significant improvement (P < 0.001) and a gain of 6 letters. The baseline higher order-root mean square (HO-RMS) was 0.89 ± 0.53 μm, which reduced to 0.38 ± 0.24 μm (P < 0.001), and RMS coma of 0.45 ± 0.29 μm improved to 0.20 ± 0.12 μm (P < 0.001). Though there was a marginal reduction from 0.04 ± 0.14 to 0.03 ± 0.07, RMS spherical aberration did not show any statistically significant difference (P = 0.37). RMS secondary astigmatism reduced from 0.17 ± 0.15 μm to 0.08 ± 0.12 μm (P = 0.007), and RMS trefoil reduced to 0.13 ± 0.09 μm from 0.64 ± 0.36 μm (P < 0.001) with SLs and showed statistically significant improvement. SLs can be considered an effective option that corrects a significant amount of HOAs and enhances visual performances in PMD eyes.

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

To evaluate the efficiency, safety, and stability of a revised tissue-saving treatment protocol in a cohort having pellucid marginal degeneration (PMD). 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. 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). 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.

Keratoconus: Ocular surface considerations, from bench to bedside

Aims/Purpose: This comprehensive systematic narrative study is aimed to describe the close interactions between the ocular surface and keratoconus with its vast spectrum of diagnostic and treatment techniques, both basic and clinical.Methods: This investigation searched PubMed, Scopus, Cochrane, Embase, and Web of Science for relevant papers published up to January 2023. The systematic review used MeSH and non‐MeSH terms. Unrestricted language and publishing schedule. After a comprehensive search, all of the search results were imported into Endnote software after a thorough search. Duplicate and less relevant citations have been eliminated in Endnote. In addition to the databases indicated, we searched Google Scholar for “Ocular surface” AND ((keratoconus) OR (“pellucid marginal degeneration”) OR (“corneal ectasia”) OR (“iatrogenic ectasia”)).Results: Treating dry eye, MGD, and blepharitis may slow KC progression and relieve symptoms. Eye rubbing and mechanical injury could spread bacteria to the eyelids, causing blepharitis. Tarsorrhaphy is the most powerful manoeuvre to help heal epithelial defects, especially in moderate and severe forms of DED. Use high‐quality eyedrops, especially preservative‐free ones, to increase tissue viscosity on the ocular surface and protect tear film to reduce epithelium injury before and after surgery. Finally, Vitamins, minerals, metal ions, and antioxidants may prevent dry eye and KC. In addition, improper air quality, wind, pollution, low humidity, watching TV, reading, and surgical procedures can cause dry eye illness, increase MMP‐9 and IL‐6 and decrease EGF during exacerbation.Conclusions: This is the first systematic narrative review to explore the mutual interaction between the ocular surface and KC and the wide spectrum of diagnostic and therapeutic options. Dry eye and tear film instability have been documented as a non‐ectatic differential diagnosis for KC and ectatic disorders. Nonetheless, KC and DED are both common topics. Future research should look into the effect of pre‐treating ocular surface health on postoperative outcome and the efficacy of the therapeutic strategy in reversing KC ocular surface changes.

Une ectasie cornéenne sévère unilatérale de l’enfant

We report a case of unilateral Terrien's marginal degeneration in a 14-year-old girl. Slit-lamp examination of the affected eye revealed 360° circumferential lipid deposits with 6mm of superior limbal distension, superficial neovascularization, a zone of corneal thinning from 3:00 to 9:00 with a zone of corneomalacia at 11:00. The remainder of the cornea was clear, without fluorescein staining or anterior chamber reaction. Terrien's marginal degeneration (TMD) is typically known to occur bilaterally in men over the age of 40. Terrien's degeneration must be differentiated from other causes of peripheral corneal thinning; the primary differential diagnosis is Fuchs' marginal keratitis. Other causes of corneal thinning must be ruled out, including Mooren's ulcer. In Terrien's degeneration, there is no central mined edge in the thinning sulcus, the epithelium remains intact, and affected patients do not present with pain. Other differential diagnoses include pellucid marginal degeneration and sulcus degeneration, which are characterized by the absence of lipid infiltrates associated with the central region of the thinning zone, thus distinguishing them from TMD. It is important to keep in mind that Terrien's marginal degeneration can occur in children.

Long-Term Follow-Up of the Effect of Accelerated CXL Protocol on Pellucid Marginal Degeneration

Long-Term Follow-Up of the Effect of Accelerated CXL Protocol on Pellucid Marginal Degeneration

Rate of fractional change in corneal tomography parameters in keratoconus using a combination of predictive parameters

BackgroundTo compare the rate of fractional change for multiple corneal tomographic factors in progressive keratoconus (KC).MethodsIn this retrospective case series, 40 eyes (40 patients) with progressive KC (increase in central keratometry of 1.00 D or maximum keratometry of 1.50 D on two visits at least six months apart) were included. Cases with previous history of ocular surgery, poor scans, corneal scars, severe dry eyes, post-excimer ectasia, pellucid marginal degeneration were excluded. Medical records, corneal tomography and anterior corneal wavefront (8 mm) (Scheimpflug tomography, Pentacam, Oculus, Germany) were analyzed. Rate of fractional change (Rx = (x1 − x0)/(|x0|tm)); where, x1 = value at follow-up, x0 = value at initial visit and tm = time in months, was measured.ResultsThe mean age of the patients was 30.0 ± 8.4 years. The mean follow-up duration was 8.9 ± 4.2 months. Coma (0.076 ± 1.4) had the largest rate of fractional change (P = 1.7 × 10−14, Kruskal–Wallis test). The rate of fractional change was higher for aberrometric parameters (anterior corneal higher-order aberrations root mean square and anterior coma) compared to pachymetric and keratometric parameters (P values ranging from 1.4 × 10−4 to 7.4 × 10−10, Mann–Whitney test, effect size ranging from 0.4–0.7). The rate of fractional change was comparable between pachymetric and keratometric factors (P > 0.05 for all comparisons, Mann–Whitney test).ConclusionsAnterior corneal wavefront, especially anterior coma, were noted to have higher rate of fractional change compared to single point keratometric and pachymetric indices in progressive KC. This information can be used for decision-making when monitoring patients with KC.

Update on Corneal Crosslinking and Topography-Guided PRK in the Management of Keratoconus, Pellucid Marginal Degeneration, and Ectasia

Introduction The introduction of Corneal Crosslinking (CXL) in countries worldwide has led to a reduction in the need for corneal transplants in patients with keratoconus. This innovative and revolutionary procedure is relatively simple in concept, easy for patients to undergo, and can provide excellent outcomes in preserving and stabilizing vision. By stiffening the collagen fibers of the cornea, CXL can prevent progressive disease and vision loss. It is imperative for all eye care professionals to understand the positive long-term impact of this procedure and how it has become the standard of care in the management of selected keratoconus patients and those with other ectatic diseases. CE Notification This article is available as a COPE accredited CE course. You may take this course for 1-hour credit. Read the article and take the qualifying test to earn your credit. Please check COPE course expiry date prior to enrollment. The COPE course test must be taken before the course expiry date.

IOCT-Assisted DSAEK Tamponade for Spontaneous Corneal Perforation with Secondary Bleb Formation in Pellucid Marginal Degeneration

Intraoperative optical coherence tomography (iOCT) is used extensively in complex anterior segment surgery, providing increased precision and thereby more safety and improved clinical outcomes. In lamellar keratoplasty, the successful application of iOCT has already been described [1]. For example, the iOCT can be used for defining the cutting depth of deep anterior lamellar keratoplasty (DALK) or for visualization of potential fluid in the interface in Descemet stripping automated endothelial keratoplasty (DSAEK) [2], [3], [4]. Moreover, for the correct corneal graft positioning in Descemet membrane endothelial keratoplasty (DMEK), a marker was previously required. The iOCT allows recognition of the corneal graft orientation and further observation of the unfolding process of the graft without the need for marking [1], [5].

Complications in deep anterior lamellar keratoplasty - A retrospective cross sectional interventional analysis in a large series.

To analyse complications in patients managed with deep anterior lamellar keratoplasty (DALK) for diseases of anterior corneal stroma. This was a retrospective analysis of all the patients who underwent DALK in a tertiary care center in South India from 2010 to 2021. A total of 484 eyes in 378 patients were included in the study. Patients who underwent DALK for advanced keratoconus, keratoconus with Bowman's membrane scar, healed hydrops, macular corneal opacity, macular corneal dystrophy, granular corneal dystrophy, spheroidal degeneration, pellucid marginal degeneration, post-LASIK ectasia, descemetocele, postcollagen cross-linking aborted melt and dense scar, and postradial keratotomy were included in the study. The patients were followed up for 17.6±9.4 months(1-10years). Complications noted in the surgery were intraoperatively Descemet's membrane perforation in 32 eyes (6.6%), postoperatively secondary glaucoma in 16 eyes (3.31%), cataract in 7 eyes (1.45%), suture-related complications in 5 eyes (1.03%), graft rejection in 3 eyes (0.61%), traumatic dehiscence in 2 eyes (0.41%), filamentary keratitis in 2 eyes (0.41%), interface infiltrate in 1 eye (0.21%), and recurrence of disease in 4 eyes (8.77%) out of 57 eyes with corneal dystrophy. DALK as an alternative to penetrating keratoplasty for anterior corneal stromal diseases has proven to be better time and again. It has become an automatic choice for diseases of anterior cornea requiring keratoplasty. Complications occurring at any stage of surgery can be identified and managed effectively resulting in optimal outcome. This article compiles complications post DALK.

Short-term visual outcome with sclerocorneal contact lens on irregular cornea.

The purpose is to study the change in visual acuity obtained with sclerocorneal contact lens (SCL) in patients with irregular corneal astigmatism. A prospective pre-post observational study was designed to include consecutive consenting patients with irregular corneal astigmatism and best-corrected visual acuity worse than 6/12 and fitted with SCL. Visual acuity was assessed using Snellen charts before fitting SCL and 1 week after the fit and converted to the equivalent logMAR units for analysis. We included 51 eyes of 41 patients with a mean age of 26.31 ± 8.86 of which 32 (78%) were men. Keratoconus was the most common indication (n = 42 eyes, 82.35%), followed by corneal scar (n = 3, 4%), post keratoplasty (n = 2, 4%), high myopia (n = 2, 4%), pellucid marginal degeneration (n = 1, 2%), and aphakia (n = 1, 2%). The mean overall uncorrected visual acuity improved significantly (P < 0.001) with SCL from 1.18 ± 0.34 logMAR (6/120 Snellen's equivalent) to 0.27 ± 0.15 (6/9 Snellen's equivalent) at 1-week post-SCL fitting. The mean overall best spectacle-corrected visual acuity improved from 0.89 ± 0.45 logMAR (6/36 Snellen's equivalent) to 0.26 ± 0.15 (6/9 Snellen's equivalent) at 1-week post-SCL fitting. Sclerocorneal contact lens improves visual acuity significantly in patients with irregular corneal astigmatism and reduces the need for corneal transplantation.

Endoilluminator-assisted management of acute hydrops in pellucid marginal corneal degeneration (PMCD) with compression sutures and intracameral perfluropropane (C3F8)

In this case, a male in his 30s presented to the clinic with blurring of vision, sudden whiteness, and pain in the left eye for 10 days. All preliminary examinations were recorded. He was a known case of Pellucid marginal corneal degeneration (PMCD). Clinical examination revealed corneal edema due to acute hydrops. Anterior segment optical coherence tomography (OCT) showed increased corneal thickness and a large descemets detachment. Endoilluminator-assisted compression sutures were placed along with intracameral C3F8 gas. As the tear was large, a 10-0 prolene suture was used instead of the conventional 10-0 nylon. This is the first case in literature in which acute hydrops in PMCD was managed with compression sutures (10-0 prolene) along with the injection of intracameral perfluropropane (C3F8) with the help of intraoperative use of endoilluminator.

Visual outcome with sclerocorneal contact lens in case of a pellucid marginal degeneration

ABSTRACT A 40-year-old male presented with progressive dimness of vision in right eye. Slit-lamp microscopy revealed features of pellucid marginal degeneration in right eye. Corneal topography showed “crab-claw” pattern of thinning. His visual acuity in right eye improved well with sclerocorneal contact lens.

Long-term outcome of limbal-sparing lamellar keratoplasty in keratoglobus: A retrospective case series

We report six eyes of five patients with keratoglobus who underwent limbal-sparing lamellar keratoplasty (LSLK) with 7 years of follow-up. In two patients’ three eyes, it was congenital and the rest had acquired keratoglobus from pellucid marginal degeneration combined with keratoconus. In LSLK, the peripheral corneal epithelium is dissected to include the stem cells and reflected along with conjunctival peritomy. The host cornea is de-epithelialized, stromal irregularities dissected, and then a corneoscleral graft denuded of Descemet’s membrane is anchored to a scleral ledge fashioned. Postoperatively, all received adequate tectonic support, and except for one posttrauma eye, the rest improved visually.

IOCT‐assisted DSAEK tamponade for spontaneous corneal perforation with secondary bleb formation in pellucid marginal degeneration

AbstractPurpose: Intraoperative optical coherence tomography (iOCT) was initially used in vitreoretinal surgery. Nowadays, iOCT is also used in anterior segment surgery, providing increased precision and therefore more safety in complex anterior segment procedures, such as in corneal transplantation.Methods: Our case reports on a 50‐year‐old patient who suffered a spontaneous corneal perforation with secondary bleb formation on the ground of advanced pellucid marginal degeneration (PMD).Results: After initial repair with histoacryl glue, the corneal perforation was successfully managed by iOCT‐guided DSAEK tamponade. The secondary bleb resolved spontaneously.Conclusion: Intraoperative optical coherence tomography is a good additional tool in complex anterior segment surgery to reach a higher precision and to provide more safety.

Intracorneal ring segments for KC and iatrogenic keratectasia

AbstractICRS are polymethylmethacrylate (PMMA) implants developed to be inserted in the corneal stroma aiming to remodel the ectatic corneal curvature. In 2000, ICRS have been introduced for the implantation in KC treatment. Since then, several authors have demonstrated the efficacy of this surgical procedure for improving the refractive and topographic results of KC patients. Moreover, the method has been extended to a larger spectrum of corneal ectasia, such as pellucid marginal degeneration (PMD) and iatrogenic ectasia after laser in situ keratomileusis (LASIK). Our aim was to evaluate the functional results, i.e. how uncorrected and corrected distance visual acuity can be improved by implantation of ICRS. Progression of ectasia seems to be retarded. However, consistent follow‐up visits at close intervals are necessary to identify complications at an early stage. The complications after ICRS implantation are rare due to strict patient selection and modern surgical techniques.

Keratoconus in Thai population - a cross-sectional hospital-based study.

Studies in the epidemiology of keratoconus are limited in Southeast Asia. A study on the prevalence and characteristics of keratoconus in the Thai population could give a general idea of its impact. To study keratoconus prevalence in patients seeking refractive surgery and analyze the characteristics of keratoconus. Medical records from April 2015 to August 2018 were retrospectively reviewed. Keratoconus and keratoconus suspect prevalence in patients seeking laser vision correction were calculated. The characteristics of keratoconus patients were reviewed. The Amsler-Krumeich classification was used to determine the stages. Topographically, the types of cones were categorized into oval, nipple, pellucid marginal degeneration (PMD)-like, and astigmatic types. Keratoconus and keratoconus suspect prevalence were 1.66% and 0.68%, respectively. Out of the affected patients, 73.8% were male. The mean age at diagnosis was 25.25 ± 8.35 years. The presenting symptoms were blurred vision (87%) and itching (47%). Stage 1 was predominant, found in 39% of patients (followed by stages 2, 4, and 3, respectively). Ocular findings comprised the Munson sign (14.63%), the Rizutti sign (6.94%), Fleischer ring (28.14%), Vogt striae (24.95%), corneal scar (8.63%), prominent corneal nerve (2.81%), and corneal staining (7.69%). Mean uncorrected visual acuity (logarithm of the minimum angle of resolution [logMAR]) was 0.88 ± 0.64. Mean corrected visual acuity (logMAR) was 0.40 ± 0.49. Mean Q-value was -0.92 ± 0.63. The thinnest pachymetry was 459.39 ± 56.96 microns. The mean keratometry was 49.7 ± 6.64 diopters. Topographically, the types of cones were oval (57%), astigmatic (33%), PMD-like (5%), and nipple type (4%). Keratoconus prevalence among Thai patients seeking refractive surgery was 1.66%. Most patients were male and presented with the disease at a mild bilateral stage in their second decade of life.