A case of severe refractive changes induced by Galyfilcon A silicone hydrogel contact lenses (original) (raw)
Related papers
Posterior Corneal Changes with Orthokeratology
Optometry and Vision Science, 2004
Purpose. To investigate changes in corneal thickness and the radius of curvature of the posterior corneal surface after orthokeratology (OK) rigid lens wear. Methods. Nineteen young myopic subjects wore reverse-geometry OK lenses (BE/ABE, Ultravision Contact Lenses, Brisbane, Australia) every night for 1 month. Central and midperipheral corneal thickness (Allergan Humphrey ultrasound, Carl Zeiss Meditec, Dublin, CA), topography (EyeSys v.3.1, Houston, TX), subjective refraction, and posterior corneal radii (video photography of Purkinje images) were evaluated within 2 h of waking, prelens wear, and on four occasions postlens wear during a 1-month period. A mixed-models approach was used to analyze the data. We modeled the changes in posterior corneal radius of curvature and corneal thickness in terms of the sagittal height of the anterior and posterior cornea using an ellipsoidal model for the corneal surfaces. Results. Refractive error reduced from ؊2.28 to ؊0.01 DS within 1 month. A significant thinning of the cornea was evident between 1 (p ؍ 0.03) and 2 weeks (p ؍ 0.0048) postlens wear. A significant increase in the anterior corneal radius of curvature was present at all time periods beyond 1 night (p < 0.001), and a significant posterior corneal flattening occurred centrally and midperipherally after 1 week (p ؍ 0.04 and p ؍ 0.013, respectively). Conclusions. These findings suggest that in addition to the significant topographic flattening of the anterior corneal surfaces, there is also a significant flattening of the posterior surface during the early adaptive stages of OK lens wear. (Optom Vis Sci 2004;81:421-426)
Cornea, 2019
Purpose: To evaluate the changes in anterior corneal topography induced by short-time wear of scleral contact lenses (SLs) in keratoconic subjects with and without a history of corneal cross-linking (CXL). Methods: Nine keratoconic patients (14 eyes) were fitted with 18.5 mm SLs for optical rehabilitation. Subjects were divided into 2 groups: 7 eyes without a history of CXL (Non-CXL group) and 7 with a history of CXL (CXL group). Corneal topography was performed at baseline and after 2 and 5 hours of lens wear. The differences for simulated flat (Kflat), steep (Ksteep) and maximal (Kmax) corneal curvatures, central corneal astigmatism (CCA), and central cornea thickness were evaluated. Results: No statistically significant difference was detected between Non-CXL and CXL groups in any of these measures. Statistically significant flattening was detected in Ksteep Repeated measures analysis of variance ([RM-ANOVA), F (2,24) = 11.32, P , 0.0001], CCA [RM-ANOVA, F (2,24) = 15.34, P , 0.0001], and Kmax [RM-ANOVA, F (2,24) = 19.10, P , 0.0001). From baseline to 5 hours of SL wear, Ksteep decreased on average from 53.1 to 52.4 D, Kmax decreased from 56.7 to 55.8 D, and CCA decreased from 7.2 to 6.3 D. Kmax showed a trend toward more flattening in the Non-CXL group. Central cornea thickness showed significant thickening over time from baseline (451 mm) to 5 hours (458 mm) of SL wear [RM-ANOVA, F (1,12) = 319.3, P , 0.0001]. Conclusions: Short-term scleral lens wear in keratoconic patients may cause flattening of the anterior cornea. A history of CXL treatment does not guarantee corneal shape stability after scleral lens wear. Practitioners should be aware of these changes because scleral lens wear may mask the signs of keratoconus progression. A scleral contact lens (SL) is a rigid gas permeable lens that rests exclusively on the bulbar conjunctiva vaulting the cornea and the limbus. Using this type of lens geometry, a tear fluid reservoir, often referred to as "lens clearance," is created between the posterior lens surface and the anterior surface of the cornea. This liquid layer created underneath the SL acts as an optical lens neutralizing both regular and irregular corneal astigmatism, and optical aberrations generated by the anterior cornea, thereby improving vision. 1,2 Visual improvement is one of the primary indications for SL fitting, in particular, for optical rehabilitation of keratoconus (KC), other forms of corneal ectasia and after keratoplasty. 3,4 In addition, the postscleral lens tear fluid reservoir hydrates the underlying ocular tissues providing relief and treatment for a variety of ocular surface diseases, such as severe dry eye, neurotrophic keratopathy, and corneal scarring. 5 Since the advent of rigid gas permeable (RGP) contact lenses (CLs), it was widely described in the literature that both the geometrical shape and physiology of the cornea might be significantly altered by corneal CL wear. Numerous factors such as desiccation, mechanical rubbing with consecutive corneal microtrauma, and suboptimal corneal oxygen-ation are thought to cause these changes. 6,7 Rigid lens wear-related corneal warpage leads to a shift in central keratometry, corneal asphericity, and low-order and high-order aberrations, contributing to decreased retinal image quality. 7,8 Recovery time is highly variable and correlates with daily wearing time and overall length of RGP wear. 9 To date, little is known regarding the effect of scleral lens wear on corneal geometry. Recently, several researchers have studied the influence of SL wear on corneal topography in normal 10-13 and keratoconic eyes. 14-16 According to reports, the shape of the anterior and posterior corneal surfaces seems to be flattened and modified by SL wear, despite the fact that SLs do not have any mechanical interaction with the underlying corneal tissue.
Apical Clearance Rigid Contact Lenses Induce Corneal Steepening
Purpose. Anecdotal reports suggest that steeply fitted rigid contact lenses can induce corneal steepening and myopic shifts in refraction. This study investigated changes in corneal topography, corneal thickness, and refraction after short-term wear of apical clearance lenses. Methods. Ten young adults participated in the study in which apical clearance lenses (Conoid, Hydron Pty. Ltd., Frenchs Forest, NSW, Australia), fitted approximately 0.3 mm steeper than the flattest keratometric reading, were worn for 4 h. A polymethyl methacrylate (PMMA) lens was worn in one eye, and a Boston XO lens (Bausch & Lomb, Rochester, NY) was worn in the other. Lenses were nonfenestrated in the first trial, and a single midperipheral fenestration was incorporated for a second trial. Corneal topography was monitored using the EyeSys topographic analysis system (EyeSys Vision, Inc., Houston, TX); central corneal thickness was quantified using ultrasonic pachometry; and refraction and anterior ocular response were also monitored. Results. Significant central corneal edema (8.2 2.2%) was demonstrated in the PMMA lens-wearing eye only. Fenestration did not reduce the edema response. We found significant corneal steepening over a 5-to 6-mm central zone, which was more pronounced in the PMMA lens-wearing eye and was modified by lens fenestration. The curvature changes altered central corneal shape from prolate (Q 0.06 0.10) to oblate (Q 0.26 0.31). A slight myopic shift in refraction (0.38 0.60 D) was found with the PMMA lenses only. Conclusions. Apical clearance lenses induce corneal steepening after short-term wear. Although corneal molding is implicated as the primary factor driving the shape change, corneal edema and postlens tear film pressures can modify this response. (Optom Vis Sci 2004;81:427-435) T here is growing interest in the use of rigid contact lenses to manipulate corneal topography for refractive purposes. Recent reports of impressive clinical results with reverse geometry rigid lens designs 1-4 have reawakened interest in the technique of orthokeratology (OK) for the reduction of myopia and astigmatism. 5 There have been no reports in the recent literature of attempts to manipulate corneal topography for hyperopic correction. In the early 1960s, Jessen 6, 7 reported successful hyperopic OK using steeply fitting polymethyl methacrylate (PMMA) lenses. In the orthofocus technique described by Jessen, lenses were fitted steeper than K (flattest keratometric reading) by the amount of desired correction in diopters; the contact lens itself was plano in power, and the tear lens created by the lens fitting supplied the desired refractive correction. Although no data were presented, Jessen 7 claimed that up to 3.50 D of hyperopia could "respond well to use of the lens" and that after at least 1 year of lens wear patients "manifested less than 1/2 of their original refractive error." 7 He also claimed that the effects were stable after lens removal, particularly in young patients. 6 Coon 8 later commented that this clinical technique was subsequently largely abandoned because of problems with corneal edema, presumably because of the use of steeply fitted lenses in oxygen-impermeable PMMA material. It is difficult to find any published studies that provide support for Jessen's claims. The early PMMA literature presented conflicting reports on corneal curvature changes even during conventional rigid contact lens wear, partly because of the difficulty in separating the effects of corneal hypoxic edema and corneal molding. It was recognized that the cornea typically demonstrated transient cor-neal steepening during the initial "adaptation" period because of central corneal edema, followed by gradual flattening presumed to be the result of corneal molding. Carney 9 was able to demonstrate that these two factors (edema and molding) provoked different and independent patterns of corneal curvature change and that steeply
Investigative Ophthalmology & Visual Science, 2003
To investigate topographical thickness changes of the epithelium and total cornea measured with optical coherence tomography (OCT) after overnight wear of rigid gas-permeable lenses. METHODS. Reverse geometry design CRT (Dk ϭ 100) rigid (test) lenses (Paragon Vision Sciences, Mesa, AZ) were randomly fitted on one eye of each of 20 neophyte subjects (mean age, 24.6 Ϯ 2.7 years) and the other eye was fitted with an alignment tricurve rigid lens of the same material (control). Epithelial and total corneal thickness was measured at intervals of 10°a cross a 10-mm zone of the horizontal meridian of the cornea, before and after overnight wear. Refractive error was measured with an autorefractor. These measurements were repeated 20 and 60 minutes and 3, 6, and 12 hours after lens removal.
Purpose: To evaluate changes in anterior corneal topography and higher-order aberrations (HOA) after 14-days of rigid gas-permeable (RGP) contact lens (CL) wear in keratoconus subjects comparing two different fitting approaches. Methods: Thirty-one keratoconus subjects (50 eyes) without previous history of CL wear were recruited for the study. Subjects were randomly fitted to either an apical-touch or three-pointtouch fitting approach. The lens' back optic zone radius (BOZR) was 0.4 mm and 0.1 mm flatter than the first definite apical clearance lens, respectively. Differences between the baseline and post-CL wear for steepest, flattest and average corneal power (ACP) readings, central corneal astigmatism (CCA), maximum tangential curvature (KTag), anterior corneal surface asphericity, anterior corneal surface HOA and thinnest corneal thickness measured with Pentacam were compared. Results: A statistically significant flattening was found over time on the flattest and steepest simulated keratometry and ACP in apical-touch group (all p < 0.01). A statistically significant reduction in KTag was found in both groups after contact lens wear (all p < 0.05). Significant reduction was found over time in CCA (p = 0.001) and anterior corneal asphericity in both groups (p < 0.001). Thickness at the thinnest corneal point increased significantly after CL wear (p < 0.0001). Coma-like and total HOA root mean square (RMS) error were significantly reduced following CL wearing in both fitting approaches (all p < 0.05).
Session III: the compromised corneal environment
Journal of The British Contact Lens Association, 1992
patients are put into when they are driving causes a problem or breakdown in that suppression, then we either advise that they do not wear lenses when they drive and simply wear spectacles, or we prescribe a third contact lens.
Acta Ophthalmologica, 2009
Corneal thickness changes were monitored across the cornea in 10 subjects during 7 days continuous wear of 3 types of hydrogel contact lenses of different back vertex powers. Analysis of topographical corneal thickness changes indicates that the periphery of the cornea swells significantly less than the central cornea. The effect is more dramatic with higher levels of central corneal oedema, and with lenses of higher minus power, in spite of their thicker lens periphery. An anoxic stimulus was also found to produce greater central than peripheral corneal swelling, indicating that tear exchange under the periphery of the contact lens is not a significant factor in limiting peripheral corneal swelling. It was concluded that the topographical swelling profile is not contact lens-related, but reflects a reduced swelling capability of the peripheral cornea, due to physical restraint in the limbal region.
Current applications and efficacy of scleral contact lenses — a retrospective study
Journal of Optometry, 2010
Purpose: To evaluate the indications and effi cacy of high gas permeable scleral contact lenses (GP-SCL). Methods: A total database of 97 consecutive patients (140 eyes) fi tted with GP-SCL between January 2003 and December 2008, was retrospectively analyzed to determine the benefi ts of fi tting scleral lenses. All lenses were fi tted by preformed technique and were non-fenestrated. Patients included keratoconus -88 eyes (63 %); corneal irregularities after penetrating keratoplasty -39 eyes (28 %); various ocular surface disorders: Stevens-Johnson syndrome (SJS), graft versus host disease (GVHD) and exposure keratopathy -6 eyes (4 %); post refractive surgery keratoectasia -4 eyes (3 %), and high refractive error -3 eyes (2 %). Results: Mean follow up was 27.5 months (range 1-71), mean wearing time in successful wearers group was 12.2 hours per day (range 10-16), mean wearing time in group of wearers who dropped out using GP-SCL, was 5.8 hours (range 3-8). Keratoconus patients achieved median best corrected visual acuity (BCVA) of 20/32, 84 % of patients achieved BCVA of 20/40 or more. The post keratoplasty group achieved median BCVA of 20/25, 92 % of patients achieved BCVA of 20/40 or better. In the other groups, median BCVA was as follows: ocular surface disorders -20/50, keratoectasia -20/30, high refractive error -20/32. Positive fl uid-venting was highly associated with successful GP-SCL wearing. Twenty patients (21 %) failed to wear GP-SCL. Conclusions: GP-SCL's expand the management of various corneal abnormalities. The main indication for GP-SCL is optical correction of an irregular corneal surface, especially keratoconus and corneal transplant.
Hypoxic Corneal Changes Following Eight Hours of Scleral Contact Lens Wear
Optometry and vision science : official publication of the American Academy of Optometry, 2016
To examine the change in corneal thickness and posterior curvature following 8 hours of miniscleral contact lens wear. Scheimpflug imaging (Pentacam HR; Oculus) was captured before, and immediately following, 8 hours of miniscleral contact lens wear for 15 young (mean age 22 ± 3 years), healthy participants with normal corneae. Natural diurnal variations were considered by measuring baseline corneal changes obtained on a separate control day without contact lens wear. Over the central 6 mm of the cornea, a small but highly statistically significant amount of edema was observed following 8 hours of miniscleral lens wear, after accounting for normal diurnal fluctuations (mean ± standard deviation percentage swelling 1.70 ± 0.98%, p < 0.0001). Posterior corneal topography remained stable following lens wear (-0.01 ± 0.07 mm steepening over the central 6 mm, p = 0.60). The magnitude of posterior corneal topographical changes following lens wear did not correlate with the extent of le...