Fitting an MSD (Mini Scleral Design) rigid contact lens in advanced keratoconus with INTACS

Keratoconus is a bilateral degenerative disease characterized by a non-inflammatory, progressive central corneal ectasia (typically asymmetric) and decreased vision. In its early stages it may be managed with spectacles and soft contact lenses but more commonly it is managed with rigid contact lenses. In advanced stages, when contact lenses can no longer be fit, have become intolerable, or corneal damage is severe, a penetrating keratoplasty is commonly performed. Alternative surgical techniques, such as the use of intra-stromal corneal ring segments (INTACS) have been developed to try and improve the fit of rigid contact lenses in keratoconic patients and avoid penetrating keratoplasties. This case report follows through the fitting of rigid contact lenses in an advanced keratoconic cornea after an INTACS procedure and discusses clinical findings, treatment options, and the use of mini-scleral and scleral lens designs as they relate to the challenges encountered in managing such a patient. Mini-scleral and scleral lenses are relatively easy to fit, and can be of benefit to many patients, including advanced keratoconic patients, post-INTAC patients and post-penetrating keratoplasty patients.     

The cascade hypothesis of keratoconus.

Keratoconus, a non-inflammatory thinning of the cornea, is a leading indication for corneal transplantation. For its causation, we propose a "Cascade Hypothesis" stating that keratoconus corneas have abnormal or defective enzymes in the lipid peroxidation and/or nitric oxide pathways leading to oxidative damage. The accumulation of oxidative, cytotoxic by-products causes an alteration of various corneal proteins, triggering a cascade of events, (i.e. apoptosis, altered signaling pathways, increased enzyme activities, fibrosis). This hypothesis is supported by biochemical, immunohistochemical and molecular data presented in this review. Based upon this evidence, one can speculate that keratoconus patients should minimize their exposure to oxidative stress. Protective steps should include wearing ultraviolet (UV) protection (in the contact lenses and/or sunglasses), minimizing the mechanical trauma (eye rubbing, poorly fit contact lenses) and keeping eyes comfortable with artificial tears, non-steroidal anti-inflammatory drugs and/or allergy medications.     

Atypical unilateral superior keratoconus in young males.

Generally in keratoconus the corneal apex displacement is inferior in position and bilateral in expression. Two young male keratoconic subjects enrolled in the Dundee University Scottish Keratoconus Study (DUSKS) demonstrated with corneal topography the presence of unilateral superior keratoconus. Successful visual rehabilitation of a superior cone with contact lens fitting represents a particular challenge to the contact lens practitioner. This report discusses the management of two such cases.     

Collaborative Longitudinal Evaluation of Keratoconus (CLEK) Study: methods and findings to date.

PURPOSE: To describe baseline and longitudinal findings of the Collaborative Longitudinal Evaluation of Keratoconus (CLEK) Study. METHODS: The CLEK Study is an 8-year, multi-center, natural history study of 1209 patients with keratoconus who were examined annually for 8 years. Its goals are to prospectively characterize changes in vision, corneal curvature, corneal status, and vision-specific quality of life. RESULTS: CLEK Study subjects had a mean age at baseline of 39.3+/-10.9 years. At study entry, 65% of the patients wore rigid contact lenses, and 14% reported a family history of the disease. Subjects exhibited a 7-year decrease in high- (2.03 letters) and low- (4.06 letters) contrast, best-corrected visual acuity, with 19% demonstrating decreases of 10 or more letters in high-contrast, best-corrected acuity and 31% of subjects demonstrating decreases of 10 or more letters in low-contrast, best-corrected acuity in at least one eye. Subjects exhibited an average 8-year increase in corneal curvature of 1.60D in the flat corneal meridian, with 24% demonstrating increases of 3.00D or more. The 8-year incidence of corneal scarring was 20%, with younger age, corneal staining, steeper baseline corneal curvature, contact lens wear, and poorer low-contrast visual acuity predictive of corneal scarring. Data from the National Eye Institute Visual Function Questionnaire suggest that the effect of keratoconus on vision-specific quality of life is disproportionate to its low prevalence and clinical severity. CONCLUSION: Although we report measures of disease severity and visual function across the CLEK sample, clinicians can begin to envisage the course of keratoconus in individual patients by determining whether factors predictive of disease progression are present in those patients.     

A case of concomitant keratoconus and granular corneal dystrophy type II

PurposeWe report a Korean case of concomitant keratoconus and granular corneal dystrophy type II.MethodsCase report.ResultsA 29-year-old man visited our clinic for a routine ocular check-up. Slit-lamp examination revealed a few well-circumscribed, greyish-white, discrete granular opacities in the central corneal stromae of both eyes. Direct sequencing of exon 4 of the BIGH3 gene revealed a heterozygous transversion from G to A in the second-nucleotide position of codon 124. In addition, a Fleischer ring and Vogt's striae were evident in the cornea. The corneal topography was suggestive of keratoconus.ConclusionGranular corneal dystrophy type II can co-exist with keratoconus and should be included in the differential diagnosis.     

An evaluation of corneal nerve morphology and function in moderate keratoconus.

PURPOSE: To investigate corneal nerve morphology and corneal sensitivity in keratoconus. METHODS: The central cornea of 13 subjects with keratoconus and 13 age-matched control subjects was assessed using in vivo confocal microscopy and corneal aesthesiometry. RESULTS: Significant differences in corneal nerve fibre density were found between the subjects with keratoconus and the control subjects (keratoconus versus control; 1018.3+/-489.6 microm versus 1820.7+/-789.5 microm; p = 0.006). The mean diameter of nerve fibres in the stroma was found to be greater in subjects with keratoconus compared to control subjects (keratoconus versus control; 10.2+/-4.6 microm versus 5.5+/-1.9 microm; p = 0.007). The orientation of corneal nerve fibres in the subjects with keratoconus appeared to be altered from the predominantly vertical orientation seen in the control subjects. Corneal touch threshold was found to be similar in the two groups, although the subjects with keratoconus using contact lens correction had reduced corneal sensitivity compared to the contact lens-wearing control subjects (keratoconus with contact lenses versus controls with contact lenses; 1.18+/-0.19 g/mm2 versus 0.98+/-0.05 g/mm2; p = 0.03). CONCLUSION: This study reveals significant reductions in nerve density in the keratoconic cornea. The thickened stromal nerve fibres observed in the keratoconic corneas may explain why prominent corneal nerves are often seen using slit lamp biomicroscopy in keratoconic patients.     

Acute corneal edema decades after penetrating keratoplasty for keratoconus in eyes wearing scleral contact lenses

PurposeTo report three cases of acute corneal edema occurring decades after penetrating keratoplasty (PK) for keratoconus in eyes wearing scleral contact lenses (ScCLs) with previously clear corneal grafts.MethodsRetrospective chart review of three ScCL wearers presenting for sudden onset pain and blurred vision. Data extracted included clinical presentation, year and reason for PK, ocular medications and comorbidities, contact lens wearing history, results of any ancillary testing available including corneal topography, anterior segment optical coherence tomography (OCT), and specular microscopy surrounding the event, treatment and outcomes of intervention. The number of PK eyes fit with ScCLs in the author’s practice was determined to estimate the prevalence of this event.ResultsThe three patients each had a longstanding PK for keratoconus performed between 33–35 years prior to presentation and recurrent ectasia. Each patient presented with an acute, painful eye and reduced vision either 3 days, 4 months or 9 years after refitting into ScCLs. Each eye had well demarcated focal microcystic epithelial and stromal edema within the graft and crossing the wound margin onto the host cornea. Although a definitive break or detachment of Descemet’s membrane was not visualized, the presentations suggest these were episodes of acute hydrops.ConclusionsLongstanding PKs with recurrent ectasia and acute focal edema suggestive of corneal hydrops is demonstrated in this case series of ScCL wearers. Although similar events have occurred as part of the natural history of post-PK corneas for keratoconus, the proximity of ScCL refitting to two of the events suggests some association.     

The prevalence of keratoconus in northern Poland: A cross-sectional study of patients from a primary healthcare practice

IntroductionKeratoconus is defined as central and/or paracentral corneal thinning and steepening with consequent irregular astigmatism. To date, no prospective study has reported its prevalence in Central Europe. This study aimed to evaluate the prevalence of keratoconus assessed with Scheimpflug imaging in a profile of general medicine practice in Poland.MethodsThis cross-sectional study collected data by inviting all patients aged 10–80 years subscribed to a single general practitioner in the Elbląg area, Poland. Corneal measurements were performed using a rotating Scheimpflug corneal tomography system. Three masked examiners established the diagnosis of keratoconus in the right or left eye. Fleiss’ kappa coefficient (κ) was used to qualitatively analyze the interexaminer agreement.ResultsOf 1,705 patients invited to the study, 771 agreed to participate (45.2%). The mean age of the 728 patients (60.6% female and 39.4% male) with gradable images in at least one eye was 53.6 ± 16.5 years. All of the examiners classified the same four cases as keratoconus (0.549%, 549 per 100,000, 95% confidence interval 150 to 1,400 per 100,000), of which two were bilateral. Fleiss’ kappa showed almost perfect agreement among the three examiners regarding the diagnostic decision (κ = 0.784, 95% confidence interval 0.750 to 0.817, p < 0.001). The keratoconus cases were all women (p = 0.106), aged 48, 69, 70, and 71 years old.ConclusionThe prevalence of keratoconus in this area was higher than that previously demonstrated in many European countries. Underestimation of the prevalence has been postulated but never demonstrated.     

Hydrogel contact lens-induced corneal warpage.

BACKGROUND: Although contact lens-induced corneal warpage is most frequently associated with PMMA lenses, approximately 27% of reported cases of corneal warpage have been attributed to hydrogel lens wear. The change in corneal contour may be the result of either mechanical deformation, chronic metabolic insult, or a combination of mechanical and metabolic challenges. Limited oxygen transmissibility through some hydrogel lenses may lead to chronic hypoxia and acidosis. These metabolic challenges can change corneal physiology sufficiently to cause clinically significant corneal warpage. CASE REPORTS: Three cases of hydrogel contact lens-induced corneal warpage are presented. In all three cases, cessation of lens wear led to restoration of the normal corneal contour and visual acuity. All patients were refit with more oxygen-permeable lenses, and have successfully resumed wearing contact lenses. CONCLUSION: Certain individuals who wear hydrogel contact lenses can experience corneal warpage. Clinical signs of corneal warpage include changes in refractive error, decreased visual acuity with spectacle correction, and changes in corneal topography. Serial topography is useful to monitor the cornea to resolution of the condition. Contact lenses with higher oxygen transmissibility will frequently alleviate the relative hypoxia that may be associated with corneal warpage.     

Role of corneal epithelial thickness mapping in the evaluation of keratoconus

PurposeTo investigate the corneal epithelial thickness profiles in patients with a confirmed diagnosis of stable and progressive keratoconus.SettingStudio Italiano di Oftalmologia, Rome, Italy.DesignObservational study.Methods86 patients with either stable (n = 52) or progressive (n = 34) keratoconus and 182 healthy controls were enrolled in the study. Disease progression was confirmed by repeated corneal topographies over 1 year follow-up before inclusion in the study. All subjects had full corneal and epithelial thickness mapping taken by spectral domain optical coherence tomography (SD-OCT). The full corneal mapping was investigated by evaluating the central corneal thickness, the thinnest point, the superonasal-inferotemporal thickness difference and the minimum-median thickness difference. The epithelial mapping was investigated by assessing the 2 mm central thickness, the inferior paracentral (2–5 mm) thickness, and the minimum-maximum thickness difference.ResultsNo significant differences in full corneal mapping were found between stable and progressive keratoconic eyes. Of note, the inferior paracentral region of the corneal epithelium was significantly thinner in progressive (50 ± 3 μm) than stable (53 ± 4 μm) keratoconus (P < 0.001).ConclusionsThe SD-OCT corneal epithelial mapping was valuable for detecting local thickness changes in eyes with keratoconus. Monitoring the corneal epithelial changes across the inferior area in patients with keratoconus could be worthy for assessing disease progression.     

The corneoscleral shape in keratoconus patients with and without specialty lens wear

PurposeTo evaluate differences in corneoscleral shape in keratoconus patients with and without specialty lenses compared to controls.MethodsA cross-sectional study was performed comparing three groups of keratoconus eyes: 24 lens-naïve keratoconus eyes (17 patients; group 1), 7 eyes with corneal lens wear (7 patients; group 2) and 7 eyes with scleral lens wear (7 patients; group 3). For comparison, 25 eyes of 25 emmetropic participants and 11 eyes of 11 astigmatic participants were included. Corneoscleral topography measurements taken with the Eye Surface Profiler (ESP, Eaglet Eye BV, Houten, Netherlands) were exported and assessed using custom-made software to demarcate the limbal radius, and to calculate sagittal height and corneoscleral asymmetry.ResultsIn non-lens wearing keratoconus patients, sagittal height was found to be significantly larger than in control eyes, in both the corneal periphery and sclera (paired t-test, pairwise comparisons p < 0.01). The level of peripheral corneal and scleral asymmetry was also significantly higher in non-lens wearing keratoconus eyes compared to controls (t-test, p < 0.01). Both corneal and scleral lens wear resulted in significant changes to the shape of the corneal periphery and sclera. In all 3 groups of keratoconus eyes, asymmetry of the peripheral cornea showed a very strong correlation with scleral asymmetry (R² = 0.90, 0.86 and 0.85 for groups 1–3, respectively).ConclusionThe corneal periphery and sclera have a distinctly different shape in keratoconus eyes compared to controls. Specialty lens wear induces significant regional changes to the shape of the anterior eye in keratoconus eyes.     

Performance and predictability of a new large diameter contact lens design in keratoconic corneae

ObjectivesTo evaluate the clinical performance and predictability using corneal topography in the fitting of a new large-diameter rigid gas permeable (RGP) contact lens design in eyes with keratoconus (KCN).MethodsThis study presents a review of eyes fitted with Alexa ES lenses for nonsurgical optimisation of visual correction. Anterior steep simulated keratometry (sim-K steep), corneal diameter (HVID), the Curvature at the apex in diopters (Cc), and distance from the corneal apex to the centre of the cornea (Lc) in millimetres derived from the Cone Location and Magnitude Index (CLMI) were recorded. Visual acuity, mean wearing time, final sagittal depth and adverse events were also recorded. Correlations between topographic indices and base curve were evaluated using the Pearson correlation coefficient.ResultsForty-six eyes from 26 patients (19 males/ 7 females) were included. Mean visual acuity improved from 0.49 ± 0.32 with glasses, to -0.02 ± 0.10 with the contact lens. The mean daily wear time was 12.19 ± 1.96 hours. No complications were detected in 95.65% of the eyes [95% CI (83.9%-99.2%)] but two episodes of non-infectious keratitis. The average sagittal depth of the lenses fitted was 0.425 ± 0.15 mm, and it was positively correlated with the Cc value (r² = 0.66, p< 0.0001, n=46) derived from the CLMI index of the pre-fitting topography.ConclusionsCorneoscleral RGP contact lenses are a safe, and effective alternative for managing KCN patients to corneal lenses. Also, clinical data derived from the corneal topography could be used to help to decide the first diagnostic lens to be assessed, easing the overall fitting process.     

Scleral shape and its correlation with corneal parameters in keratoconus

PurposeTo assess the correlation of the scleral shape and corneal tomographic parameters in keratoconus.MethodsTwenty eyes of 15 keratoconus patients with no previous specialty lens wear or ocular surgery were included in this study. Corneal imaging was obtained with the Pentacam HR and three-dimensional (3D) corneoscleral maps were acquired using the Eye Surface Profiler, ESP. Sagittal height was calculated at the central corneal level (annulus of 0–4 mm radius), peripheral cornea (annulus 4–6 mm radius) and sclera (annulus 6–8 mm radius) using ESP maps and Pentacam HR (exclusively for the central cornea). The flattest and steepest regions of each annulus and the circumferential scleral asymmetry were calculated based on custom-made software. The Pearson correlation coefficient (r) was used to evaluate the correlation between corneal parameters as measured by Pentacam HR and scleral asymmetry.ResultsAnterior corneal parameters, such as flattest and steepest keratometry, were found to be correlated with scleral asymmetry in keratoconus (all r>0.5, p < 0.05). In contrast, anterior astigmatism showed poor correlation with the level of scleral irregularity (r=-0.11; p = 0.32). Other disease-specific parameters pertaining to the posterior corneal curvature and corneal thickness were not correlated with scleral asymmetry. The steepest regions of the central cornea, peripheral cornea, and sclera tended to share a common angle (r = 0.92; p < 0.001 for central cornea compared to sclera).ConclusionAnterior corneal parameters measured by corneal imaging are associated with the level of scleral asymmetry and the orientation of the steepest area of the sclera in eyes with keratoconus.     

Progressive keratoconus in patients older than 48 years

PurposeTo report cases of progressive keratoconus (KC) in patients aged ≥48 years and the successful arrest of progression using corneal cross-linking (CXL) with riboflavin and ultraviolet-A light.ObservationsFive eyes from four patients with progressive KC aged 48, 48, 51 and 54 years are reported in this case series. All eyes were followed regularly after initial diagnosis. K_max was used as an indicator of progression and KC progressed at a rate of 1.4 diopters in 6 months and 14.6 diopters in 14 months. All patients eventually received CXL, and all were aged ≥50 years at the time of the procedure. One eye required two CXL procedures to successfully stabilize the patient’s cornea.ConclusionDespite the probability of KC progression strongly declining after the age of 40 years, it never becomes zero. It is therefore advisable to continue regular follow-up corneal tomography examinations in patients with KC, even in their fifth and sixth decades of life.     

Corneal changes following short-term rigid contact lens wear

PurposeThe aim of this cross-over study was to investigate the changes in corneal thickness, anterior and posterior corneal topography, corneal refractive power and ocular wavefront aberrations, following the short term use of rigid contact lenses.MethodFourteen participants wore 4 different types of contact lenses (RGP lenses of 9.5 mm and 10.5 mm diameter, and for comparison a PMMA lens of 9.5 mm diameter and a soft silicone hydrogel lens) on 4 different days for a period of 8 h on each day. Measures were collected before and after contact lens wear and additionally on a baseline day.ResultsAnterior corneal curvature generally showed a flattening with both of the RGP lenses and a steepening with the PMMA lens. A significant negative correlation was found between the change in corneal swelling and central and peripheral posterior corneal curvature (all p ≤ 0.001). RGP contact lenses caused a significant decrease in corneal refractive power (hyperopic shift) of approximately 0.5 D. The PMMA contact lenses caused the greatest corneal swelling in both the central (27.92 ± 15.49 μm, p < 0.001) and peripheral (17.78 ± 12.11 μm, p = 0.001) corneal regions, a significant flattening of the posterior cornea and an increase in ocular aberrations (all p ≤ 0.05).ConclusionThe corneal swelling associated with RGP lenses was relatively minor, but there was slight central corneal flattening and a clinically significant hyperopic change in corneal refractive power after the first day of lens wear. The PMMA contact lenses resulted in significant corneal swelling and reduced optical performance of the cornea.     

Analysis of corneal tomography in select Black and LatinX children

PurposeKeratoconus (KC) is a bilateral and often asymmetric disease which can progress to corneal thinning and protrusion. Keratoconus in children appears to be more aggressive than in adults. Research on pediatric keratoconus is limited, and treatments rely on research and experience in adult populations. The current study aimed to provide an analysis on the distribution of the corneal tomography measurements in an underserved, Black and LatinX, primarily low-income pediatric population.MethodsThis was a prospective study approved by the Illinois College of Optometry’s IRB. A total of 2133 children, presented to a school-based vision clinic within the Chicago Public Schools, were included in the analysis and were classified into three age groups: 3–6 years, 7–12 years, and 13–18 years. Four specific tomography measurements were obtained from the Pentacam (BAD Final D, ART-Max, I-S Ratio, and Thinnest Point Asymmetry).ResultsThe mean front corneal astigmatism of the study cohort was ?1.39D ± 1.45. Tomography indices means were 0.95 ± 0.74 for BAD Final D, 457.34 ± 94.83 for ART-Max, 0.01 ± 0.68 for I-S ratio, and 9.60 ± 25.55 for Thinnest Point Asymmetry. A statistically significant difference was observed among age groups for BAD Final D (p < 0.001), ART-Max (p < 0.001) and Thinnest Point Asymmetry (p = 0.006).ConclusionThis study provided the first set of normative data for a pediatric population on the four tomography measurements, offering a reference for potential diagnosis of keratoconus for Black and LatinX children. Further study could include evaluation of additional races along with a comparison with the adult data, which will provide guidance on evaluating the current keratoconus diagnosis criteria to aid early diagnosis of keratoconus in the pediatric population.     

Calculated tear oxygen tension under contact lenses offering resistance in series: piggyback and scleral lenses.

BACKGROUND: Models of oxygen delivery to the cornea with contact lens wear have considered the customary situation of one lens being worn on the cornea. However, two lenses, such as a rigid lens piggybacked on a soft lens, may be worn by patients with special ocular and visual needs. This paper extends existing single lens models to circumstances where two lenses offer resistance to oxygen in series. METHODS: Theoretical oxygen tensions are calculated for tear layers trapped beneath piggyback contact lens systems (and scleral lenses) and the anterior corneal surface with a simple single chamber corneal model using a personal computer software spreadsheet. RESULTS: Acceptable values are anticipated for contact lens materials of modern oxygen permeability values of approximately 60-100 Fatt Dk units under open eye conditions. CONCLUSIONS: The results of this spreadsheet model of oxygen supply to the anterior corneal surface offer a useful guide to clinicians concerned about providing their patients with physiologically acceptable piggyback lens systems.     

Progression of keratoconus in patients wearing pancorneal toric edge rigid gas-permeable contact lenses

PurposeTo investigate the rate of progression of keratoconus in patients wearing pancorneal toric edge rigid gas-permeable contact lenses (pancorneal RGP-CL) compared to non-pancorneal RGP-CL. We also evaluated alterations in anterior chamber parameters with the progression of keratoconus and investigated the location of the cone in eyes with keratoconus.MethodsThe current study was a retrospective study including patients with clinically evident keratoconus from the outpatient clinic from the Department of Ophthalmology of the Erasmus Medical Center, Rotterdam, the Netherlands. Medical history and contact lens characteristics were documented. All participants underwent ophthalmic examination including corneal topography. Corneal topography was repeated at one of the consecutive visits of the patient. Patients were divided into two groups: those wearing pancorneal RGP-CL and those wearing other contact lens types. As a measure of progression of keratoconus differences in corneal topography parameters between both groups were compared.ResultsA total of 82 patients were included of which 42 had follow-up (mean 17.8 months) data. We found a significant difference in progression between eyes fitted with and without pancorneal RGP-CL (K-flat: p = 0.09, K-steep: p = 0.02, K-mean: p = 0.02, and K-minimum: p = 0.04). Compared with eyes fitted without pancorneal RGP-CL no significant difference in K-values was found for eyes fitted with pancorneal RGP-CL during follow-up. Furthermore, a significant decrease in anterior chamber volume (p < 0.001) and corneal volume (p = 0.008) was found during follow-up. In 86.6% the location of the cone was located infero-temporal.ConclusionsPancorneal RGP-CL have a better effect on stabilizing progression of keratoconus than non-pancorneal RGP-CL. The finding of an infero-temporal location of the cone in keratoconic corneas may improve results of contact lens fitting and surgical management.     

Posterior cornea and thickness changes after scleral lens wear in keratoconus patients

PurposeTo evaluate the changes in the corneal thickness, anterior chamber depth and posterior corneal curvature and aberrations after scleral lens wear in keratoconus patients with and without intrastromal corneal ring segments (ICRS).MethodsTwenty-six keratoconus subjects (36.95 ± 8.95 years) were evaluated after 8 h of scleral lens wear. The subjects were divided into two groups: those with ICRS (ICRS group) and without ICRS (KC group). The study variables evaluated before and immediately after scleral lens wear included corneal thickness evaluated in different quadrants, posterior corneal curvature at 2, 4, 6 and 8 mm of corneal diameter, posterior corneal aberrations for 4, 6 and 8 mm of pupil size and anterior chamber depth.ResultsThere was a statistically significant corneal thinning (p < 0.05) in the inferior region of the KC group and in the superior region of the ICRS group. No change (p > 0.05) in the anterior chamber depth was found. The KC group showed a steepening (p < 0.05) in the temporal quadrant and a flattening that mainly affected to the superior-nasal quadrant. The ICRS group showed a steepening (p < 0.05) that mainly affected to the superior-nasal quadrant. Regarding posterior corneal aberrations, only changes (p < 0.05) in Z4 for 8 mm and Z8 for 4 mm were found in the KC group.ConclusionsShort-term scleral lens wear showed a thinning of the cornea and changes in the posterior corneal curvature affects different regions in keratoconus patients with and without ICRS.