Marginal Degeneration Research Articles

Impact of Scleral Lenses on Visual Acuity and Ocular Aberrations in Corneal Ectasia: A Comprehensive Review.

Corneal ectasias, including keratoconus (KC), pellucid marginal degeneration (PMD), and post-LASIK ectasia, poses significant visual rehabilitation challenges due to the resultant irregular astigmatism, myopia, and higher-order aberrations (HOAs). These conditions often resist traditional corrective methods, necessitating advanced optical solutions. Scleral lenses (SLs) have emerged as a primary non-surgical option for managing these complex corneal irregularities. SLs form a smooth optical interface by forming a tear-filled chamber between the lens and the cornea, effectively mitigating HOAs and improving both high-contrast and low-contrast visual acuity (VA). This review evaluates the efficacy of SLs in enhancing VA and reducing aberrations in patients with corneal ectasia. It also explores the technological advancements in SLs, such as profilometry and wavefront-guided systems, which enable more precise and customized lens fittings by accurately mapping the eye's surface and addressing specific visual aberrations. The current body of evidence demonstrates that custom SLs significantly improve visual outcomes across various ectatic conditions, offering superior performance compared to conventional correction methods. However, challenges such as the complexity of fitting and the need for precise alignment remain. Ongoing innovations in SL technology and customization are likely to further enhance their clinical utility, solidifying their role as an indispensable tool in the management of corneal ectasias.

Prospective In Vivo Confocal Microscopy of the Central Cornea in Terrien Marginal Degeneration.

To analyze central corneal in vivo confocal microscopy (IVCM) in Terrien marginal degeneration (TMD). An observational prospective case-control study. Ten Finnish patients with TMD from a tertiary referral center were compared with 10 age- and sex-matched healthy volunteers. Seven patients had bilateral TMD. Age, anterior segment optical coherence tomography, extent of thinning in clock hours, grade of microdots, and stage of TMD were analyzed. According to Süveges and Wang classification, the median stage of TMD was 2 (range, 2-3) and 2 (range, 2-6), respectively. Twelve (71%) of 17 eyes with clinical TMD showed corneal thinning at all clock hours. The median age at the time of examination was 70 years (range, 28-81), and the median time from diagnosis 8.8 years (range, 6.0-15.2). By IVCM, the epithelium, subepithelial nerve plexus, and endothelium were intact in all eyes. The anterior stroma showed bilateral hyperreflective dots in the central cornea beneath the subepithelial nerve plexus in all eyes, and larger patches were detected in the posterior stroma anterior to Descemet membrane; both were invisible by anterior segment optical coherence tomography. As compared with controls, the grade of anterior microdots increased faster with age before the age of 65, and that of posterior stromal patches was higher. Two patients additionally had bilateral hyperreflective needle-like deposits in the anterior and midstroma. By IVCM, TMD is characterized regardless of clinical laterality by bilateral microdots in the central corneal stroma. They might be a supporting diagnostic criterion and alone could suggest subclinical disease.

Efficiency and safety of the Russian-made KERATOLINK device used to treat patients with stage I–II keratoconus and pellucid marginal corneal degeneration

Efficiency and safety of the Russian-made KERATOLINK device used to treat patients with stage I–II keratoconus and pellucid marginal corneal degeneration

An unusual case of inflammatory Terrien’s marginal degeneration with pseudo pterygium

An unusual case of inflammatory Terrien’s marginal degeneration with pseudo pterygium

Anpassung von Skleral-Kontaktlinsen bei Terrien‘s marginaler Hornhautdegeneration

Purpose. This case report describes the possible visual rehabilitation with scleral lenses of a patient with Terrien’s marginal degeneration with different degrees of progression between the right and left eye. Material and Methods. Scleral contact lenses were fitted with the help of corneal tomography and by observing and assessing the fit of measuring lenses. A slit lamp with a corresponding camera helped to modify the diagnostic lenses. Results. In this case, the fitting of scleral contact lenses resulted in an improvement in distance vision in both the right and left eye. Near vision could not be evaluated at the time of writing. Conclusion. Scleral contact lenses can be a good alternative to glasses for complex corneas to improve visual performance. It is recommended to use a slit lamp with a camera to make it easier to discuss scleral contact lenses modifications with the manufacturer of the lenses. Keywords: TERRIEN’S MARGINAL CORNEAL DEGENERATION, PELLUCIDE MARGINAL CORNEAL DEGENERATION, SCLERAL LENSES

Compression sutures: A rescue to failed intracameral gas injection in massive non-resolving corneal hydrops of long duration in advanced pellucid marginal corneal degeneration (PMCD)

To describe the application of full-thickness compression corneal sutures along with intracameral gas injection in a case of non-resolving long-duration hydrops of pellucid marginal corneal degeneration with a large Descemet membrane (DM) tear. Corneal hydrops is a complication of conditions such as keratoconus (KC), pellucid marginal corneal degeneration (PMCD), and keratoglobus. Intracameral gas injection in the form of sulfur hexafluoride (SF6) or perfluoro propane (C3F8) has been known to shorten the recovery period by tamponading the break. The application of corneal sutures to approximate the widely separated ends of the DM tear may also be performed. All these are management options described for acute hydrops. We report two cases of application of full-thickness compression corneal sutures along with intracameral gas injection in a case of non-resolving long-duration hydrops of more than 2 months duration in PMCD with a large DM tear. Full-thickness corneal compression sutures and intracameral gas injection can restore the imperviousness of posterior stroma after hydrops. This technique is safe and effective for faster resolution of corneal edema post hydrops and early visual rehabilitation.

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.

Tenon patch graft repair in an unusual case of leaking wound after phacoemulsification

Leaking corneal incisions after phacoemulsification can be associated with devastating consequences and can lead to secondary complications including endophthalmitis, choroidal hemorrhage, and glaucoma. We report a case of leaking corneal wound after routine phacoemulsification at the site of corneal thinning associated with terrien marginal degeneration (TMD), which was missed preoperatively, consequently leading to this surgical complication. TMD is a rare form of ectatic corneal condition with a very slow progression. The main aim of treatment is to improve the vision and corneal integrity, owing to its uncertain etiology. Surgical intervention in TMD, however, has been advocated when perforation is imminent, but the chance of spontaneous and intraoperative perforation increases in cases with severe thinning of corneas resulting in poor visual outcomes as compared to non-perforated eyes. In our case, as an amniotic membrane or corneal tissue was not available at the time of presentation, we proceeded with a Tenon patch graft with the application of cyanoacrylate glue, following which a bandage contact lens was applied. This case highlights the importance of a meticulous preoperative workup of the patient to identify any abnormality of the cornea, especially at the incision sites, to avoid such complications during the surgery.

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.

Cataract surgery after lamellar wedge resection in advanced pellucid marginal degeneration: a case report

Cataract surgery after lamellar wedge resection in advanced pellucid marginal degeneration: a case report

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.

Does Corneal Topography Using 3-Dimensional Optical Coherence Tomography Suggest Different Subtypes of Terrien Marginal Degeneration?

The aim of this study was to analyze corneal topography relative to astigmatism, higher order aberrations, and corneal curvatures in Terrien marginal degeneration using 3-dimensional anterior-segment optical coherence tomography. Twenty-nine eyes of 15 Finnish patients from a tertiary referral center had topographic axial power maps classified into 4 patterns by visual grading: crab claw (CC), mixed (M), arcuate (A), and normal. Regular astigmatism, keratometry, higher order aberrations, maximal corneal thinning, apex thickness, and curvature changes relative to best fit sphere toward maximal peripheral thinning were compared. Four, 9, and 12 eyes were classified as CC, M, and A, respectively; 1 as normal with clinical disease; and 3 as normal with unilateral disease. Median follow-up was 2.3 (range, 0-7.2) years. Three eyes changed pattern. Patients with the CC pattern were the youngest when diagnosed, progressed more rapidly, exhibited cavities in superior quadrants with anterior bulging, and had greater higher order posterior aberrations. Patients with the M pattern were older, progressed slower, and showed superonasal asymmetric corneal steepening extending centrally, often with asymmetric bow tie. Patients with pattern A showed little progression and were the oldest when diagnosed, with maximal corneal thinning equally in all quadrants. According to the Wang classification, the median stage was 4, 2, and 2 in CC, M, and A patterns, respectively, whereas it was always 2 by the Süveges classification. Terrien marginal degeneration is characterized by distinct corneal topographic patterns that differ in tomographic features, suggesting existence of subtypes in addition to different stages of disease. Patients representing CC and M patterns might benefit from more frequent monitoring.

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.

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.