A pilot study on corneal Langerhans cells in keratoconus.

PURPOSE: To report the density and morphology of cells that are analogous to corneal Langerhans cells and their associations in keratoconus. MATERIALS AND METHODS: This prospective cross-sectional study included a convenience sample of keratoconus subjects aged between 18-65 years. Corneal topography, assessment of ocular symptoms, tear variables, corneal sensitivity, in-vivo confocal microscopy were performed. The number of Langerhans cells were manually counted and averaged across three central corneal images. Cell morphology was graded on a 0-3 scale, where grade 3 indicates cells with long visible dendrites. Associations of Langerhans cells with other variables were evaluated using Spearman's correlation. RESULTS: Twenty-one keratoconus subjects with a mean age of 43±11 years were included. Eighty-one percent of them were males, 48% had mild keratoconus and 52% were contact lens wearers. Langerhans cells were present in the central cornea in 91% of subjects. Median cell density was 15 cells/mm2(IQR: 3-21). Cell morphology of grades 2 or 3 (with short or long dendrites) was seen in 71% of subjects. There was a significant association between Langerhans cell frequency and density with male gender (rho and p-values: -0.669, 0.001 and -0.441,0.045) and between Langerhans cell density and nerve fibre tortuosity (0.479,0.028). No significant association observed with age, contact lens wear or ocular symptoms. CONCLUSION: Langerhans cells were present in a significant number of subjects suggesting the possibility of inflammation in keratoconus. Based on the association of Langerhans cells with nerve parameters, we propose inflammation as the underlying cause for corneal nerve changes in keratoconus.

Scleral lens after intracorneal ring segments in patients with keratoconus.

BACKGROUND: To report the use of scleral lens (ScCL) to improve vision in patients having keratoconus who had intracorneal ring segment (ICRS) surgery. METHODS: Two eyes of two keratoconus patients fitted with ScCL (PROSE - prosthetic replacement of the ocular surface ecosystem, USA) after having undergone ICRS surgery are reported as noncomparative interventional case series. The ICRS implanted were INTACs and kerarings. Indications, visual acuity with ScCL, complications and follow-up are reported. RESULTS: Case 1 underwent ScCL trial as he was referred for keratoplasty for being contact lens intolerant after ICRS surgery. Case 2 was intolerant to both corneal rigid gas permeable (RGP) lens and soft contact lens (SCL). 18.5 and 18mm diameter ScCLs were dispensed to Case 1 and 2 respectively. The ScCLs had adequate corneal clearance with no corneal touch. There was no staining of the cornea or vascularization with the lens use. Case 1 complained of double images during trial with different Front surface eccentricity (FSE). A ScCL that did not cause diplopia was ordered. At four months of lens wear, the patient had diplopia with ScCL, which cleared when second lens with changed FSE was dispensed. Case 2 used SCL for five years before ScCL was fitted. He used the same ScCLs for five years. ScCL use resulted in improved comfort and visual acuity of 20/20. No complications were noted. CONCLUSIONS: ScCL may be tried in patients who have ICRS and are intolerant to corneal RGP or SCL and before subjecting such patients to keratoplasty.

Role of Scleral Contact Lenses in Management of Coexisting Keratoconus and Stevens-Johnson Syndrome.

PURPOSE: To report the rare coexistence of keratoconus and Stevens-Johnson syndrome (SJS) managed with scleral contact lenses (ScCLs). METHODS: This is a retrospective case series. Five patients (9 eyes) who had coexisting SJS and corneal ectasia were identified from the database during the 2-year period. Diagnosis of SJS was based on a positive history of drug reactions, signs of ocular surface disease, and the presence of keratinization of lid margins. Keratoconus was diagnosed by slit-lamp biomicroscopy. RESULTS: Five eyes of 3 patients had coexisting SJS and keratoconus and were dispensed with ScCLs (PROSE, prosthetic replacement of the ocular surface ecosystem; Boston Foundation for Sight, Needham Heights, MA). All these patients had photophobia. Visual acuity improved in all these patients with ScCL wear. Two patients (4 eyes) were excluded from this study because they had SJS with generalized corneal thinning from limbus to limbus, corneal opacification, and pannus. One patient developed deep vessels in the cornea on prolonged ScCL wear. Reduction in the ScCL wear schedule and change of material with a higher Dk resulted in regression of vascularization. Case 3 developed conjunctival congestion and was uncomfortable wearing ScCLs, although visual acuity was 20/40. He discontinued using ScCL wear. CONCLUSIONS: Keratoconus, a noninflammatory condition of the cornea coexisted with inflammatory SJS. Managing such patients with ScCLs may improve vision and comfort.

Change in vault during scleral lens trials assessed with anterior segment optical coherence tomography.

PURPOSE: To assess the change in vault during scleral lens fitting with anterior segment optical coherence tomography (AS-OCT). METHODS: This study comprised of patients who had AS-OCT performed after 1h and 4h of scleral lens wear (PROSE, prosthetic replacement of the ocular surface ecosystem, Boston Foundation for Sight, Needham Heights, MA, USA). Vault was measured on AS-OCT as the distance between the front surface of the cornea in the center and the back surface of the scleral lens. RESULTS: Fifty eyes of 41 patients were analyzed. The main indications for scleral lens trial were ectasia (keratoconus, post surgery) (n=20 eyes) and ocular surface disease (OSD - Stevens - Johnson syndrome, dry eyes and limbal stem cell deficiency) (n=30 eyes). Mean age of the patients was 31.4 years. Twenty were males. The diameter of the scleral lens ranged from 16mm to 18.5mm. Vault measurements reduced in 45/50 eyes (90%), remained same (n=2) or increased (n=3). Overall mean vault decreased from 680±421µm at 1h to 589±355µm (p=<0.001) at 4h of lens wear. Mean vault in ectasia was 759±574µm and 634±455µm (p=0.02) at 1h and 4h of lens wear respectively. In OSD group, mean vault was 626±276µm and 558±273µm (p<0.01) at 1h and 4h of lens wear respectively. Average reduction in the vault was 125µm in ectasia and 68µm in OSD group. CONCLUSION: Vault reduced significantly after 4h of lens wear during scleral lens trial indicating that the final assessment of the scleral lens may be done after 4h of lens wear.

Pilot Study of Corneal Sensitivity and Its Association in Keratoconus.

PURPOSE: To evaluate corneal sensitivity and its association with other clinical parameters in keratoconus. METHODS: Twenty-four subjects with keratoconus aged between 18 and 65 years were recruited in this cross-sectional study. Ocular symptoms, corneal topography, tear variables such as tear osmolarity, volume and lower tear meniscus height, ocular surface staining, central sensitivity threshold (CST), and corneal subepithelial nerve mapping were obtained. Association between central CST and other clinical variables was examined using the Spearman correlation coefficient. Partial correlation was performed to control for effects of confounding factors. RESULTS: Data from the most severe eye of each subject were included in analyses. Based on the maximum simulated keratometry (Kmax) reading, subjects were graded as having mild (N = 11; K max ≤ 52 D) or severe (N = 13; K max > 52 D) keratoconus. Central corneal sensitivity was lower (ie, increased CST) in the severe keratoconus group compared with that in the mild keratoconus group (median, interquartile range: 1.09; 0.60-19.66 vs. 0.51; 0.39-1.51 g/mm, P = 0.035). In bivariate correlations, reduced corneal sensitivity in keratoconus was associated with age (ρ = 0.42, P = 0.040), disease duration (ρ = 0.49, P = 0.015) and severity (ρ = 0.44; P = 0.032), lower central nerve fiber density (ρ = -0.68, P = 0.014), contact lens wear (ρ = 0.44; P = 0.025), and contact lens tolerance (ρ = 0.46; P = 0.033). After adjusting for contact lens wear, reduced corneal sensitivity was negatively associated with ocular symptoms (ρ = -0.426, P = 0.048) and pain sensitivity (ρ = -0.423, P = 0.045) and positively associated with corneal staining (ρ = 0.52, P = 0.011). CONCLUSIONS: Altered corneal sensitivity in keratoconus affected ocular symptoms and ocular surface health, which may have significant impact on the success of management options for keratoconus.

Outcome of Keratoconus Management: Review of the Past 20 Years' Contemporary Treatment Modalities.

OBJECTIVES: To describe the past 20 years' contemporary management modalities for keratoconus (KC) and their outcomes and failures and to propose recommendations in reporting their outcomes. METHODS: A systematic review of the literature on KC management options for the last 20 years was performed. Original articles that reported the outcome of any form of KC management other than full-thickness or lamellar corneal graft were reviewed to collect information on their outcomes and complications and the level of scientific evidence of the study. RESULTS: A total of 1,147 articles retrieved and of those, 241 satisfied the inclusion criteria, and 41.1% of them were prospective case series. The higher level of evidence studies, that is, randomized controlled trials (RCTs), were limited to only one intervention, that is, corneal collagen cross-linking (CXL). However, the quality of most RCTs was limited because of performance and detection bias. Contact lenses (CLs) remain the mainstream of KC management and were associated with reversible and non-sight-threatening complications. Surgical options such as intracorneal segment implantation and phakic intraocular lens are considered in the visual rehabilitation of CL intolerants, and CXL is the only available option to stop or delay the disease progression. Generally, these surgical procedures are associated with transient inflammatory events and permanent sequelae. CONCLUSIONS: The published studies on KC management options varied significantly with respect to the study population, age of participants, severity of KC, clinical outcome measurements, and follow-up period. High-quality longer follow-up RCTs are required to evaluate the long-term effects of KC interventions.

Scleral contact lenses in the management of pellucid marginal degeneration.

PURPOSE: To assess visual improvement with scleral lenses (PROSE, prosthetic replacement of the ocular surface ecosystem, Boston Foundation for Sightight, USA) in patients with Pellucid marginal degeneration (PMD). METHODS: This is a single-center, retrospective case-series involving patients with clinical PMD who underwent scleral lens-PROSE trial for improvement of visual acuity, from January 2009 to December 2012 at a tertiary center in India. Scleral lenses with different front surface eccentricities (FSE) were tried for improvement of visual acuity. Snellen visual acuity before and with PROSE wear was noted. Complications with PROSE wear to follow-up were noted. RESULTS: PROSE was dispensed to 12 patients (20 eyes) out of 19 patients having PMD. Location of PMD was inferior in fourteen and superior in two eyes. Four eyes had co-existing keratoconus. Nine were males and three were females. The indications for scleral lens were lens popping-out, failure of piggy-back contact lens and RGP failure. LogMAR Visual acuity improved significantly from 0.45±0.31 pre-PROSE to 0.05±0.08 post-PROSE (p=0.0001). The FSE ordered was 0.6 in 17 eyes, 0.3 in one eye and 0.8 in two eyes. Three patients had hydrops over follow-up; two patients underwent keratoplasty and one was managed conservatively with steroids and hyperosmotic agents. Seven patients did not order PROSE: reasons were - no perceived improvement in visual acuity (n=2), wanted to decide (n=2), continued glasses (n=1) and continued RGP contact lens (n=1). One patient had difficulty with self lens insertion. CONCLUSION: PROSE improves visual acuity in PMD; three patients developed hydrops over follow-up.

Scleral lens for keratoconus: technology update.

Scleral lenses are large diameter lenses which rest over the sclera, unlike the conventional contact lenses which rest on the cornea. These lenses are fitted to not touch the cornea and there is a space created between the cornea and the lens. These lenses are inserted in the eyes after filling with sterile isotonic fluid. Generally, scleral contact lenses are used for high irregular astigmatism as seen in various corneal ectatic diseases such as keratoconus, pellucid marginal degeneration, or/and as liquid bandage in ocular surface disorders. In this article, we review the new developments, that have taken place over the years, in the field of scleral contact lenses as regard to new designs, materials, manufacturing technologies, and fitting strategies particularly for keratoconus.

Contact lens in keratoconus.

Contact lenses are required for the visual improvement in patients with keratoconus. Various contact lens options, such as rigid gas permeable (RGP) lenses, soft and soft toric lenses, piggy back contact lenses (PBCL), hybrid lenses and scleral lenses are availble. This article discusses about selection of a lens depending on the type of keratoconus and the fitting philosophies of various contact lenses including the starting trial lens. A Medline search was carried out for articles in the English language with the keywords keratoconus and various contact lenses such as Rose k lens, RGP lens, hybrid lens, scleral lens and PBCL.

RGP contact lens fitting in keratoconus using FITSCAN technology.

PURPOSE: To assess and compare the base curve (BC) of rigid gas permeable contact lens (RGP) that were calculated by FITSCAN using corneal topography (Orbscan IIz) and the diagnostic contact lens fitting method in keratoconus eyes. MATERIALS AND METHODS: A prospective comparative study of 85 keratoconus eyes was conducted. Two masked observers calculated the contact lens parameters of RGP lens by diagnostic fitting method and using FITSCAN technology. The base curves calculated by two methods were compared using Wilcoxon signed rank test and agreement between two methods were analysed using Bland-Altman plot. RESULTS: Eighty-five eyes from 55 keratoconus patients were included in the study. The mean age was 17.63±2.78 (range: 12-23) years and among them 46 were males. The keratoconus was graded into mild, moderate and severe based on average keratometry values. The base curve calculated by the FITSCAN is on average 0.22mm higher than that calculated by diagnostic method (P value <0.0001, 95% CI=0.155, 0.245, Wilcoxon signed rank test) and the bias between the two methods was found to be 2.7% (Bland-Altman plot), indicating systematic bias between the two modalities. By single linear regression analysis, the base curve of RGP contact lens could calculated by using the formula, base curve (BC)=(FITSCAN calculated BC×0.86563)+0.78738. CONCLUSION: Our study showed that selecting the BC of the initial trial lens 0.22mm steeper than the FITSCAN calculated base curve, may help to reduce the complexity of RGP contact lens fitting in keratoconus.

The effect of daily lens replacement during overnight wear on ocular adverse events.

PURPOSE: Compared with daily disposable wear schedule, continuous wear (CW) or extended wear of contact lenses has been associated with an increased risk of developing an ocular infection. Proof-of-principle studies were conducted to investigate the impact of daily replacement of lenses on the rate of contact lens-related ocular adverse events (AEs) during 30-night CW. METHODS: A total of 215 subjects were dispensed with silicone hydrogel lenses on a 30-night CW schedule but replaced lenses daily either each night before sleeping (n = 178 eyes) or each morning after waking (n = 252 eyes). Scheduled clinic visits were conducted at 1 week and 1 month. Neophytes were required to complete 1 week of daily wear before commencing CW. A historical control (n = 191 eyes) using the same site, subject demographics, and visit schedule but monthly lens replacement was used for AE rates. RESULTS: Logistic regression analysis showed a significant reduction in mechanical AEs (0.8 vs 5.2%, p = 0.01) and overall AEs (inflammatory and mechanical events) (4.0 vs 8.9%, p = 0.04) when lenses were replaced each morning compared with being replaced monthly. Estimation of handling-related lens contamination of unworn lenses in a subgroup of subjects showed isolation of Staphylococcus aureus from the lenses of 35% of subjects, and 65% of subjects had more than 1000 colony-forming units per lens of gram-positive bacterial contamination. CONCLUSIONS: Morning lens replacement during CW reduced mechanical and overall ocular AEs. Replacing lenses at night had no beneficial effects perhaps because the benefit of a fresh lens at night might be partially negated by contamination of the contact lens caused by lens handling before overnight eye closure. Contact lens wearers on an extended wear or CW schedule should be advised to minimize lens handling before sleep to reduce the risk of complications.

Fluid filled scleral contact lens in pediatric patients: challenges and outcome.

PURPOSE: To study the indications and the challenges while fitting scleral contact lens (ScCL) filled with fluid prior to lens insertion in pediatric patients. METHODS: We retrospectively reviewed charts of patients of 16 years or less who received ScCL (PROSE - Prosthetic Replacement of the Ocular Surface Ecosystem, Boston Foundation for Sight, Needham Heights, MA, USA) that were filled with fluid (Normal saline) before lens insertion during July 2006 to April 2010. The main goal of ScCL fitting was to improve vision in patients having keratoconus (KC) and improve the ocular microenvironment in ocular surface disease (OSD). Visual acuity before and after lens wear was noted. RESULTS: Fluid-filled ScCL were dispensed to 15 patients (20 eyes). The indications for ScCL fitting were KC (n = 3 eyes), Stevens Johnson syndrome (SJS, n = 13 eyes), radiation keratopathy (n = 1 eye), combined KC and SJS (n = 1 eye) and KC and vernal keratoconjunctivitis (VKC, n = 2 eyes). Mean age of the patients was 12.85 years. The average daily lens wear was 9 h. The vision improved by 2 lines or more in 85% and dropped by 2 lines or more in 45% eyes after 4 h of lens wear due to tear debris collection. None of the patients had any complications. Patients were self sufficient inserting and removing ScCL. Two patients had broken lenses during the follow-up. CONCLUSIONS: ScCL are useful for pediatric patients who have OSD, irregular astigmatism or the two coexisting; KC combined with VKC or SJS, helping to maintain the health of the ocular surface and improves vision in these patients.

Prevalence of contact lens related complications in a tertiary eye centre in India.

AIM: To determine the prevalence of contact lens related complications in a tertiary eye care centre in India. METHODS: A retrospective review of the charts of 1255 patients who visited our contact lens clinic during 2001-2004 was conducted. The inclusion criteria included patients of at least 18 years of age, having refractive errors and keratoconus. Exclusion criteria included previous corneal surgeries and pediatric patients. 190 subjects with lens related complications were identified from among 923 patients who were using lenses. RESULTS: The prevalence of contact lens complications was 20.58%. Females with complications were more common (59.47%). The complications were more common in students. The most common complications were contact lens induced papillary conjunctivitis (CLPC) (6.39%), corneal vascularisation (4%), and superficial punctate keratitis (SPK) (3.5%). The total complications were less prevalent in patients wearing rigid gas permeable (RGP) lenses as compared to soft contact lenses. Infectious keratitis was noted in 8 eyes. Pseudomonas aeuroginosa was the most common organism isolated. The average daily wear with RGP lenses was 11.04±3.7h and 10.96±3h with soft contact lens. The highest number of complications was noted in 47.89% patients who were wearing lenses for excess of 11h. The number of patients with complications arising due to sleeping with the lenses was 74 (38.95%). CONCLUSION: Prevalence of contact lens complications was more in soft contact lens wearers compared to RGP wearers. CLPC was the most common complication followed by vascularisation and SPK.