Contact Lens Prescribing Trends for Keratoconus at an Academic Medical Center: Increased Utilization of Scleral Lenses for Severe Disease.

OBJECTIVES: To describe contact lens prescription trends for patients with keratoconus. METHODS: Demographics, corneal curvature, visual acuity, and type of contact lens prescribed were reviewed for all patients with keratoconus evaluated in the contact lens service in 2010 and 2020. RESULTS: There were 292 patients in 2010 and 217 in 2020. In 2010, 69% were using corneal gas-permeable lenses (GP), 16% soft toric, 13% hybrid, and 2% soft sphere with no scleral lens (SL). In 2020, 60% were using corneal GP, 22% SL, 12% soft toric, 5% hybrid, and 1% soft sphere. Mean log of minimum angle of resolution visual acuities with manifest refraction were (represented in mean [SD, range]) 0.42 (0.33, 0-1.3) in 2010 and 0.35 (0.33, 0-1.6) in 2020 improving to 0.19 (0.18, 0-1.3; P≤0.01) and 0.13 (0.14, 0-0.60; P<0.01) with contact lenses. Mean keratometry measurement in patients using SLs was 53.0 diopters (D) (9.9, 42.1-84.5), which was steeper than 46.6 D in patient's using all other lens types in 2010 and 2020 (3.9, 40.9-57.9; P<0.01). CONCLUSIONS: Scleral lens prescription increased during the past decade; however, corneal GP lenses remain the most frequent lens prescribed for patients with keratoconus in this cohort. Despite being prescribed for patients with the most advanced disease, SLs provide good visual acuity.

Accuracy and repeatability of self-measurement of interpupillary distance.

PURPOSE: To determine the accuracy and repeatability of participants determining their own interpupillary distance (PD). METHODS: Fifty-two healthy and naïve participants were enrolled and analyzed. All participants analyzed were without strabismus. Participants had PD measurements taken by a trained examiner using both a PD rule and an optical pupillometer. Participants then, following online instructions measured their own PD in a mirror, measured a friend's PD and used an online application downloaded to an IPod. Measurements were repeated twice for each type, and the pupillometer results were considered the gold standard (referent). RESULTS: The mean difference between the examiner PD rule measurement and the pupillometer were +0.59 mm [95% limits of agreement (LoA) -0.69 to +1.88], pupillometer-self +0.46 mm (-5.22 to +6.14), pupillometer-friend +2.00 mm (-3.80 to +7.81), and pupillometer-App -3.24 mm (-3.09 to +9.57). Measurements of repeatability using the 95% LoA for the examiner are -0.79 to 0.73 mm for the pupillometer and -1.04 to +1.20 mm for the PD rule. Participants' repeatability for the self-measurement (mirror) was -3.61 to +4.75 mm, employing a friend was -3.74 to +3.94 mm, and using the IPod application was -6.63 to +6.51 mm. CONCLUSIONS: Participants' ability to measure their own PD using techniques and applications available via the Internet result in poor accuracy and poor repeatability.

Risk factors for interruption to soft contact lens wear in children and young adults.

PURPOSE: The purpose of this study was to describe age and other risk factors for ocular events that interrupt soft contact lens (SCL) wear in youth. METHODS: A retrospective chart review of SCL wearers aged 8 to 33 years at the first observed visit was conducted at six academic eye care centers in North America. Data were extracted from all visits during the observation period (>3 years). Clinical records that documented conditions resulting in an interruption of SCL wear "events" were scanned, masked for age and SCL parameters, and then adjudicated to consensus diagnosis. Generalized estimating equations were used to examine the effect of selected covariates, including age, on the risk of an event. RESULTS: Chart review of 3549 SCL wearers yielded 522 events among 426 wearers (12%). The risk of an event increased from ages 8 to 18 years, showed modest increases between ages 19 and 25 years, and then began to decline after age 25 years. New lens wearers (<1 year) were less likely to experience events (p = 0.001). Lens replacement schedule and material were also predictive of interruptions to SCL wear with the lowest risk in daily replacement and hydrogel lens wearers (both p < 0.0001). CONCLUSIONS: These results suggest that the risk of events that interrupt SCL wear peaks in late adolescence and early adulthood and reflects risk factors identified in prospective contact lens studies. Relative to older teens and young adults, patients younger than 14 years presented with significantly fewer events resulting in interrupted lens wear.

Contact lens assessment in youth: methods and baseline findings.

PURPOSE: To describe the Contact Lens Assessment in Youth (CLAY) Study design and report baseline data for a multicenter, retrospective, observational chart review of children, teenagers, and young adult soft contact lens (SCL) wearers. METHODS: Clinical charts of SCL wearers aged 8 to 33 years were reviewed at six colleges of optometry. Data were captured retrospectively for eye care visits from January 2006 through September 2009. Patient demographics, SCL parameters, wearing schedules, care systems, and biomicroscopy findings and complications that interrupted SCL wear were entered into an online database. RESULTS: Charts from 3549 patients (14,276 visits) were reviewed; 78.8% were current SCL wearers and 21.2% were new fits. Age distribution was 8 to <13 years (n = 260, 7.3%), 13 to <18 years (n = 879, 24.8%), 18 to <26 years (n = 1,274, 36.0%), and 26 to <34 years (n = 1,136, 32.0%). The sample was 63.2% females and 37.7% college students. At baseline, 85.2% wore spherical SCLs, 13.5% torics, and 0.1% multifocals. Silicone hydrogel lenses were worn by 39.3% of the cohort. Daily wear was reported by 82.1%, whereas 17.9% reported any or occasional overnight wear. Multipurpose care systems were used by 78.1%, whereas another 9.9% indicated hydrogen peroxide solutions use. CONCLUSIONS: This data represent the SCL prescribing and wearing patterns for children, teenager, and young adult SCL wearers who presented for eye care in North American academic clinics. This will provide insight into SCL utilization, change in SCL refractive correction, and risk factors for SCL-related complications by age group.

CLMI: the cone location and magnitude index.

PURPOSE: To develop an index for the detection of keratoconic patterns in corneal topography maps from multiple devices. METHODS: For development, an existing Keratron (EyeQuip) topographic dataset, consisting of 78 scans from the right eyes of 78 healthy subjects and 25 scans from the right eyes of 25 subjects with clinically diagnosed keratoconus, was retrospectively analyzed. The Cone Location and Magnitude Index (CLMI) was calculated on the available axial and tangential curvature data. Stepwise logistic regression analysis was performed to determine the best predictor(s) for the detection of keratoconus. A sensitivity and specificity analysis was performed by using the best predictor of keratoconus. Percent probability of keratoconus was defined as the optimal probability threshold for the detection of disease. For validation, CLMI was calculated retrospectively on a second distinct dataset, acquired on a different topographer, the TMS-1. The validation dataset consisted of 2 scans from 24 eyes of 12 healthy subjects with no ocular history and 4 scans from 21 eyes of 14 subjects with clinically diagnosed keratoconus. Probability of keratoconus was calculated for the validation set from the equation determined from the development dataset. RESULTS: The strongest significant sole predictor in the stepwise logistic regression was aCLMI, which is CLMI calculated from axial data. Sensitivity and specificity for aCLMI on the development dataset were 92% and 100%, respectively. A complete separation of normals and keratoconics with 100% specificity and 100% sensitivity was achieved by using the validation set. CONCLUSIONS: CLMI provides a robust index that can detect the presence or absence of a keratoconic pattern in corneal topography maps from 2 devices.

The association of contact lens solution use and Acanthamoeba keratitis.

PURPOSE: To investigate Acanthamoeba keratitis (AK) risk factors. Diagnosis of AK, a rare but serious corneal infection, has recently increased significantly at the University of Illinois at Chicago (UIC) Cornea Service. DESIGN: Retrospective case-control study. METHODS: settings: University, tertiary care hospital. patients: Fifty-five AK cases with contact lens use were diagnosed between May 1, 2003 and September 15, 2006. Clinic-matched controls with contact lens use were recruited. Subjects completed surveys targeting lens hygiene, contact lens solution use, and water exposure. main outcome measure: Acanthamoeba keratitis. RESULTS: Thirty-nine (73.6%) cases and 113 (65.3%) controls participated; 38 cases had complete contact lens data. Thirty-five of 38 cases (92.1%) and 47 of 100 controls (47.0%) used soft lenses. Analysis was performed on 30 cases and 39 controls with matched pairs with soft lens use. Exclusive use of Advance Medical Optics (AMO) Complete MoisturePlus Multi-Purpose Solution was independently associated with AK in multivariable analysis (55.2% vs 10.5%; odds ratio [OR], 16.67; 95% confidence interval [CI] 2.11 to 162.63; P = .008). However, 38.8% of cases reported no use of AMO Complete MoisturePlus Multi-Purpose Solution either alone or in combination with other solutions. Although not statistically significant, additional hygiene-related variables (solution "reuse," lack of "rubbing," and showering with lenses) suggest a pattern of risk. CONCLUSIONS: AMO Complete MoisturePlus Multi-Purpose Solution use is independently associated with AK among soft contact lens users. However, it does not explain all cases, suggesting additional factors. Further research into environmental risk factors and hygiene practices is warranted, especially considering this is the second outbreak of an atypical, contact lens-related infection.

Epidemiological characteristics of a Chicago-area Acanthamoeba keratitis outbreak.

PURPOSE: To characterize Acanthamoeba keratitis (AK) cases and analyze the geographical distribution within the Chicago-Gary-Kenosha metropolitan area, Chicago, Illinois, USA. DESIGN: Retrospective, population-based cohort study. METHODS: All AK cases diagnosed at the University of Illinois at Chicago Cornea Service from June 1, 2003, to November 30, 2005, were included in analysis. Patients with keratitis were defined as cases through confocal microscopy, histology, and/or positive cultures. Exploratory analyses were performed to evaluate whether AK cases were unequally distributed geographically. County population data were extracted from US Census 2000 data, and rates were age-standardized to Cook County. Poisson regression analysis was used to estimate the age-standardized rate ratio (RR) between AK cases and county of residence. Current cases (June 1, 2003 to November 30, 2005) were compared with historical cases (June 1, 2000 to November 30, 2002) to determine if the current rate of AK diagnosis differed from historical rates. RESULTS: Forty AK cases were diagnosed between June 1, 2003 and November 30, 2005. The average (+/-SD) age of patients with AK was 28.0 +/- 15.0 years (range, 13 to 70 years), 52.5% were men, and 95.0% wore contact lenses. Estimated RR measures demonstrated increased rates for all counties relative to Cook, and were significant for both DuPage County (RR 3.59; 95% confidence interval [95% CI] 1.44, 8.39) and Will County (RR 3.66; 95% CI 1.18 to 9.56). Current AK diagnosis rates were significantly higher than historical rates (RR 6.67; 95% CI 3.05 to 17.52). CONCLUSIONS: AK cases are increasing in frequency. The increased rates are unevenly distributed in the study area. Further research is warranted to better understand the increase and unusual geographical distribution.

Filamentous fungal invasion of a methafilcon contact lens.

PURPOSE: To report a case of Fusarium species invasion of a methafilcon matrix soft contact lens in a first-time lens wearer. RESULTS: The authors describe the history and ocular examination of a 19-year-old woman with large fungal deposits on her contact lens. Culture of the contact lens grew Fusarium species. On histologic examination, fungal filaments were seen on both surfaces of the contact lens as well as invading the lens matrix. The fungal morphology changed as the fungus penetrated the contact lens. CONCLUSION: To our knowledge, this is the first documented case of fungal invasion of a methafilcon matrix lens and the second histologically documented case of Fusarium invasion of a contact lens.

A new method for grading the severity of keratoconus: the Keratoconus Severity Score (KSS).

PURPOSE: To define a new method for grading severity of keratoconus, the Keratoconus Severity Score (KSS). METHODS: A rationale for grading keratoconus severity was developed using common clinical markers plus 2 corneal topographic indices, creating a 0 to 5 severity score. An initial test set of 1012 eyes, including normal eyes, eyes with abnormal corneal and topographic findings but not keratoconus, and eyes with keratoconus having a wide range of severity, was used to determine cutpoints for the KSS. Validation set 1, comprising data from 128 eyes, was assigned a KSS and compared with a clinician's ranking of severity termed the "gold standard" to determine if the scale fairly represented how a clinician would grade disease severity. kappa statistics, sensitivity, and specificity were calculated. A program was developed to automate the determination of the score. This was tested against a manual assignment of KSS in 2121 (validation set 2) eyes from the Collaborative Longitudinal Evaluation of Keratoconus (CLEK) Study, as well as normal eyes and abnormal eyes without keratoconus. Ten percent of eyes underwent repeat manual assignment of KSS to determine the variability of manual assignment of a score. RESULTS: From initial assessments, the KSS used 2 corneal topography indices: average corneal power and root mean square (RMS) error for higher-order Zernike terms derived from the first corneal surface wavefront. Clinical signs including Vogt striae, Fleischer rings, and corneal scarring were also included. Last, a manual interpretation of the map pattern was included. Validation set 1 yielded a kappa statistic of 0.904, with sensitivities ranging from 0.64 to 1.00 and specificities ranging from 0.93 to 0.98. The sensitivity and specificity for determining nonkeratoconus from keratoconus were both 1.00. Validation set 2 showed kappa statistics of 0.94 and 0.95 for right and left eyes, respectively. Test-retest analysis yielded kappa statistics of 0.84 and 0.83 for right and left eyes, respectively. CONCLUSION: A simple and reliable grading system for keratoconus was developed that can be largely automated. Such a grading scheme could be useful in genetic studies for a complex trait such as keratoconus requiring a quantitative measure of disease presence and severity.

Longitudinal changes in corneal curvature in keratoconus.

PURPOSE: This study was designed to identify factors that predict longitudinal increases in corneal curvature as measured by the First Definite Apical Clearance Lens (FDACL) and flatter keratometric reading (Flat K) in keratoconus. METHODS: The Collaborative Longitudinal Evaluation of Keratoconus (CLEK) Study is a long-te rm evaluation of the natural history of keratoconus involving 1209 patients. This report uses 8 years of follow-up data from 1032 patients who had penetrating keratoplasty in neither eye at baseline and who provided enough data to compute the slope of the change with time in the FDACL or the Flat K. Outcome measures included the aforementioned slopes and whether the FDACL or the Flat K increased by 3.00 or more diopters (D) in at least 1 eye. RESULTS: At CLEK Study entry, patients were aged 38.9 +/- 10.8 years. Overall, 44.3% of them were women, and 69.3% of them were white. The slope of the change in FDACL (0.18 +/- 0.60 D/y) and Flat K (0.20 +/- 0.80 D) during 8 years translates into expected 8-year increases of 1.44 D in FDACL and 1.60 D in Flat K. Increases of > or = 3.00 D in either eye had an 8-year incidence of 24.8% for FDACL and 24.1% for Flat K. Independent predictors of increased FDACL included younger age, poorer baseline high-contrast manifest refraction visual acuity, and non-white race. Younger age and poorer high-contrast manifest refraction visual acuity were independent predictors of a >3.00-D increase for both FDACL and Flat K. CONCLUSION: CLEK patients exhibited a slow but clear increase in corneal curvature. Younger age and poorer high-contrast manifest refraction visual acuity at baseline predicted the rate of change in corneal curvature.

Differences in keratoconus as a function of gender.

PURPOSE: To characterize gender differences in the Collaborative Longitudinal Evaluation of Keratoconus (CLEK) Study. DESIGN: Observational, longitudinal study. METHODS: A total of 1209 subjects at 16 clinics. For eye-specific categorical variables, the number of eyes per subject with the characteristic was counted. For eye-specific continuous variables, the mean of both eyes was calculated. Multivariate linear (for continuous outcomes) and logistic (for categorical outcomes) regression models were created for each baseline characteristic with statistically significant (P < or = .05) differences between men and women. Age, race, education, and corneal curvature were covariates. RESULTS: The women were older, more likely to report a family history of keratoconus, more likely to be nonwhite, and less likely to complete college than men. Vogt's striae and monocular and binocular high-contrast entrance acuity were the only visual characteristics that varied between men and women in the multivariate model. Women were more likely than men to report ocular symptoms of dryness and complaints based upon a composite score of ocular symptoms. Women reported more hours per day of near work and were less likely to report the ability to wear contact lenses for enough hours to permit reading at home in the evening. Women reported more visits to their eye care practitioner during the previous 12 months. NEI-VFQ results revealed differences in self-reported difficulty with distance activities and driving. CONCLUSIONS: Gender differences exist in patient history, vision, and ocular symptoms in keratoconus patients.

Repeatability of autorefraction and axial length measurements after laser in situ keratomileusis.

PURPOSE: To assess the repeatability and agreement of refractive error measurements and the repeatability of axial length (AL) measurements in patients after laser in situ keratomileusis (LASIK). SETTING: The Ohio State University College of Optometry, Columbus, Ohio, USA. METHODS: Subjective refraction, autorefraction measurements with the Grand Seiko and Humphrey autorefractors, and AL measurements with the IOLMaster were completed for 40 previously myopic LASIK patients under noncycloplegic and cycloplegic conditions on 2 separate occasions. RESULTS: The mean difference between visits for axial length measurements was 0.008 mm +/- 0.04 (SD). The between visits repeatability for all refractive error measurements were <0.75 diopter (D). The mean difference between the subjective refraction and the Humphrey autorefractor for spherical equivalent was statistically significant under noncycloplegic conditions (-0.90 D, P<.0001) and cycloplegic conditions (-2.05 D, P<.0001). The mean difference between subjective refraction and Grand Seiko autorefraction measurements was not significant under noncycloplegic conditions (+0.05 D, 95% limits of agreement [LoA]=-0.99, 1.09; P=.52) conditions but was statistically significant, but not clinically relevant, under cycloplegic conditions (+0.17 D, 95% LoA=-0.73, 1.07; P=.03). CONCLUSIONS: Refractive error measurements after LASIK using the Grand Seiko autorefractor are reliable and agree well with subjective refraction measurements.

Lysosomal hydrolase staining of conjunctival impression cytology specimens in keratoconus.

PURPOSE: This study sought to assess the feasibility of impression cytology for the determination of conjunctival intracellular lysosomal hydrolase (acid esterase) levels in patients with keratoconus. METHODS: Twenty-two patients with keratoconus currently enrolled in the Collaborative Longitudinal Evaluation of Keratoconus (CLEK) Study and 22 age-and sex-similar controls underwent impression cytology. Samples were collected from each subject and control pair on the same day. The cells of the respective specimens were fixed immediately and were stained for acid esterase with use of identical batches of fixatives and stains. After staining, the specimens were cleared in xylene for mounting in synthetic resin on glass slides. The acid esterase staining intensity of each specimen was quantified as the percentage of light transmitted with use of an image analysis system (Zeiss). Multiple cells from each specimen were analyzed for each sample collected. RESULTS: Mixed model analysis was used to account for the subject-control pairings and for the multiple cells from each sample. With this method, the mean light transmission for normal controls (mean = 63.0; standard error [SE] = 3.0) was highly statistically significantly different from that for the keratoconus subjects (mean = 52.4; SE = 3.0) (two-tailed p= 0.0032). CONCLUSIONS: This study establishes the feasibility of adapting an acid esterase staining technique to conjunctival cells collected via impression cytology. Higher levels of lysosomal enzyme staining in patients with keratoconus have been previously reported by other investigators using full-thickness conjunctival specimens. We also demonstrate the value of using objective microspectrophotometry in measuring lysosomal enzyme staining with impression cytology specimens.

Characterization of patients who report compliant and non-compliant overnight wear of soft contact lenses.

PURPOSE: To describe compliant and non-compliant overnight wear (EW) of soft contact lenses from a large observational study. METHODS: A retrospective chart review of 3211 SCL patients with known EW status (aged 8-33yrs, SCL power +8.00 to -12.00D) captured data from 10,516 clinical visits (2006-2009). Status of EW was either daily wear (DW), compliant EW (overnight wear of US Food & Drug Administration (US FDA) EW-approved lenses), non-compliant EW (overnight wear of DW-approved lenses). The effect of demographic and clinical characteristics on the likelihood of reporting EW was examined using logistic regression. Additionally, the effect of these same characteristics on the likelihood of non-compliant EW was assessed with logistic models. RESULTS: Eight-hundred and eight patients (25.2%) reported EW. Non-compliant EW was reported by 6% of wearers (13 hydrogel, 2 silicone hydrogel brands) In multivariate models, patient age and lens replacement schedule were significant factors for EW (vs. DW) and for non-compliant (vs. compliant) EW (p<0.0001). Other factors significantly related to EW were gender, smoking, lens material, sphere power, and years of CL wear (p≤0.007, all). CONCLUSIONS: Young people (ages 18-25yrs), males, smokers, myopes, silicone hydrogel lens wearers and patients with >1yr of CL wear were significantly more likely to report EW. Non-compliant EW occurred often in young people and daily disposable wearers, though many brands had non-compliant EW use. Understanding who is likely to wear EW and non-compliant EW will help clinicians pointedly counsel patients more at risk on best practices with EW.

Age and other risk factors for corneal infiltrative and inflammatory events in young soft contact lens wearers from the Contact Lens Assessment in Youth (CLAY) study.

PURPOSE: To describe age and other risk factors for corneal infiltrative and inflammatory events (CIEs) in young, soft contact lens (SCL) wearers and to model the age-related risk. METHODS: A multicenter, retrospective chart review of 3549 SCL wearers (8-33 years at first observed visit, +8.00 to -12.00D, oversampling <18 years) captured CIEs from January 2006 to September 2009. The review noted age, sex, SCL worn, use of lens care products, and SCL wearing history. Event diagnoses were adjudicated to consensus by reviewers masked to wearer identity, age, and SCL parameters. Significant univariate risk factors for CIEs were subsequently tested in multivariate generalized estimating equations. RESULTS: Charts from 14,305 visits observing 4,663 SCL years yielded 187 CIEs in 168 wearers. Age was a significant nonlinear risk factor, peaking between 15 and 25 years (P < 0.008). Less than 1 year of SCL use was protective versus longer years of wear (P < 0.0003). Use of multipurpose care products (2.86×), silicone hydrogels (1.85×), and extended wear (2.37×) were significantly associated with CIEs in the multivariate model (P < 0.0001 each). CONCLUSIONS: Patient age, years of lens wear, use of multipurpose care products, silicone hydrogels, and extended wear were all significantly associated with CIEs with SCL wear. Use of SCLs in young patients aged 8 to 15 years was associated with a lower risk of infiltrative events compared with teens and young adults. In terms of safety outcomes, SCLs appear to be an acceptable method of delivering optics designed to manage myopia progression in children and young teens in the future.

The role of crumbs genes in the vertebrate cornea.

PURPOSE: To evaluate the role of crumbs genes and related epithelial polarity loci in the vertebrate cornea. METHODS: The authors used histologic analysis and electron microscopy to evaluate the corneas of zebrafish mutant for a crumbs locus oko meduzy (ome) and in mutants of four other loci, nagie oko (nok), heart and soul (has), mosaic eyes (moe), and ncad (formerly glass onion), that function in the same or related genetic pathways. In parallel, they performed an evaluation of corneas in human carriers of a crumbs gene, CRB1, and mutations using topography and biomicroscopy. The expression of the CRB1 gene in the normal human cornea was examined by polymerase chain reaction (PCR) and immunohistochemical staining. RESULTS: The corneas of zebrafish mutants display severe abnormalities of the epithelial and stromal layers. The epithelial cells do not properly adhere to each other, and fluid-filled spaces form between them. In addition, the layering of the corneal stroma is poorly formed or absent. The corneas of human carriers of CRB1 mutations display shape deviations compared with what has been observed in normal individuals. A PCR product of the correct size was obtained from normal human corneal samples. Sequence analyses confirmed its identity to be the human CRB1 gene. Immunohistochemical staining using anti-CRB1 yielded positive brown deposits in the human cornea. CONCLUSIONS: crumbs genes play a role in the differentiation of the vertebrate cornea. Corneal defects associated with crumbs gene mutations are very severe in the zebrafish model and, in comparison, appear clinically less pronounced in the human eye.

CRB1 gene mutations are associated with keratoconus in patients with leber congenital amaurosis.

PURPOSE: To present an association of mutations in the CRB1 gene with keratoconus in patients with Leber congenital amaurosis (LCA). METHODS: Sixteen patients with genotyped LCA (having the CRB1, CRX, RetGC, RPE65, and AIPL1 mutations) were recruited from one ophthalmology practice and examined for the presence of keratoconus. Corneal topography, visual acuity, and slit lamp biomicroscopic examination were performed in all cases. RESULTS: The mean age of the patients was 34.5 years (range, 13-74). Visual acuities ranged from 20/40 to light perception. Corneal topography was successfully collected in 15 of the cases. Five of the 16 cases had slit lamp and/or topographic features consistent with keratoconus. One patient had a clinical picture that was keratoglobus-like. Of these six cases, four had a CRB1 mutation and two had a CRX mutation. Of the three subjects with the CRX mutation, one had keratoconus, one had the keratoglobus-like presentation, and one was normal. Our cohort represents 14 separate, unrelated families. Only one family comprised multiple members with LCA. These were three affected brothers, one with keratoconus, all with CRB1 mutations. CONCLUSIONS: Although the results cannot exclude other gene mutations, they suggest that LCA patients with a CRB1 mutation may have a particular susceptibility to keratoconus.

Microbial keratitis and the role of rub and rinsing.

Recent outbreaks of microbial keratitis in contact lens wearers have involved various pathogens, including Acanthamoeba and Fusarium species. Specific reasons for the marked increase in microbial keratitis, particularly those involving species typically rarely involved in contact lens infection, remain unknown. Possible contributing factors include inadequacies of various multipurpose solutions against certain pathogens; inadequate lens care hygiene, including elimination of the digital rubbing step; poor contact lens storage case hygiene; and the introduction of new soft contact lens materials that may promote adherence of certain pathogens, particularly when a digital rubbing step is eliminated. Although there is some conflict of opinion in the literature regarding the necessity for a mechanical rub during lens cleaning and disinfection, growing evidence supports the reestablishment of a digital rub component to multipurpose solution lens care systems. This article reviews the literature on whether such a process should be recommended to contact lens wearers.

Simulation of machine-specific topographic indices for use across platforms.

PURPOSE: The objective of this project is to simulate the current published topographic indices used for the detection and evaluation of keratoconus to allow their application to maps acquired from multiple topographic machines. METHODS: A retrospective analysis was performed on 21 eyes of 14 previously diagnosed keratoconus patients from a single practice using a Tomey TMS-1, an Alcon EyeMap, and a Keratron Topographer. Maps that could not be processed or that contained processing errors were excluded from analysis. Topographic indices native to each of the three devices were recorded from each map. Software was written in ANSI standard C to simulate the indices based on the published formulas and/or descriptions to extend the functionality of The Ohio State University Corneal Topography Tool (OSUCTT), a software package designed to accept the input from many corneal topographic devices and provide consistent display and analysis. Twenty indices were simulated. Linear regression analysis was performed between each simulated index and the corresponding native index. A cross-platform comparison using regression analysis was also performed. RESULTS: All simulated indices were significantly correlated with the corresponding native indices (p < 0.01), with a mean R of 0.84, ranging from 0.42 to 0.99. Cross-platform comparisons were nonsignificant for specific indices and devices. CONCLUSION: Topographic indices native to three devices were successfully simulated. Cross-platform comparisons may be limited for specific indices.

Gas-permeable contact lenses can protect against ocular trauma: two cases.

PURPOSE: To report two cases of rigid gas-permeable contact lens wearers who were protected from serious foreign body-related injury through the wearing of their contact lenses. METHODS: Two case reports. RESULTS: Rigid gas-permeable contact lenses appear to have protected the eyes of two patients from probable serious injury. CONCLUSIONS: Rigid gas-permeable contact lenses can have a protective effect against some types of trauma, although they are not recommended to be used for protective purposes.