Padmaja Sankaridurg

Decrease in Rate of Myopia Progression with a Contact Lens Designed to Reduce Relative Peripheral Hyperopia: One-Year Results

PURPOSE To determine whether a novel optical treatment using contact lenses to reduce relative peripheral hyperopia can slow the rate of progress of myopia. METHODS Chinese children, aged 7 to 14 years, with baseline myopia from sphere -0.75 to -3.50 D and cylinder ≤1.00 D, were fitted with novel contact lenses (n = 45) and followed up for 12 months, and their progress was compared with that of a group (n = 40) matched for age, sex, refractive error, axial length, and parental myopia wearing normal, single-vision, spherocylindrical spectacles. RESULTS On adjusting for parental myopia, sex, age, baseline spherical equivalent (SphE) values, and compliance, the estimated progression in SphE at 12 months was 34% less, at -0.57 D, with the novel contact lenses (95% confidence interval [CI], -0.45 -0.69 D) than at -0.86 D, with spectacle lenses (95% CI, -0.74 to -0.99 D). For an average baseline age of 11.2 years, baseline SphE of -2.10 D, a baseline axial length of 24.6 mm, and 320 days of compliant lens wear, the estimated increase in axial length (AL) was 33% less at 0.27 mm (95% CI, 0.22-0.32 mm) than at 0.40 mm (95% CI, 0.35-0.45 mm) for the contact lens and spectacle lens groups, respectively. CONCLUSIONS The 12-month data support the hypothesis that reducing peripheral hyperopia can alter central refractive development and reduce the rate of progress of myopia. (chictr.org number, chiCTR-TRC-00000029 or chiCTR-TRC-00000032.).

Spectacle lenses designed to reduce progression of myopia: 12-month results.

Purpose. To report the results of 12-month wear of three novel spectacle lens designs intended to reduce peripheral hyperopic defocus and one standard design control lens and their effect on the progression of myopia in Chinese children aged 6 to 16 years. Methods. Chinese children (n = 210) with myopia (−0.75 D to −3.50 D sphere, cylinder ≤−1.50 D) were randomized to one of four groups wearing either one of three novel spectacle lens designs (types I, II, or III) or conventional, single-vision spectacle lenses. Data were collected at 6 and 12 months. Primary and secondary outcome measures were the changes in central cycloplegic auto-refraction and eye axial length, respectively. Peripheral refraction along the horizontal meridian (nasal and temporal) was taken at baseline with and without spectacle lenses. Multivariate linear regression was used to adjust analyses for important covariates. Results. Progression in eyes wearing control spectacle lenses at 6 and 12 months was −0.55 D ± 0.35 D and −0.78 ± 0.50 D, respectively. For the entire group, no statistically significant differences were observed in the rates of progression with the novel designs in comparison to control spectacle lenses. However, in younger children (6 to 12 years) with parental history of myopia (n = 100), there was significantly less progression (−0.68 D ± 0.47 D vs. −0.97 D ± 0.48 D) with lens type III compared with control spectacles (mean difference, 0.29 D, std error, 0.11, p = 0.038). Conclusions. There were no statistically significant differences in the rate of progression of myopia between the control and novel lens wearing eyes for the age group 6 to 16 years. The finding of reduced progression of myopia with type III lens design in younger children with parental myopia needs to be validated in a more targeted study.

Hypoxic effects on the anterior eye of high-Dk soft contact lens wearers are negligible.

Purpose. To determine whether the eyes of high-Dk soft contact lens wearing subjects can be discriminated from non–contact lens wearing subjects. Methods. This study was a prospective masked assessment of 32 subjects, 16 of whom wore experimental high-Dk soft contact lenses and 16 of whom did not wear contact lenses. Subjects wore high-Dk lenses on a 30-night replacement schedule for an average of 9 months. Tear film characteristics, staining and vascularization of the cornea, conjunctival staining, and the presence of microcysts in the corneal epithelium were assessed using slitlamp microscopy. The endothelium was examined for polymegethism. Results. No differences were found between the two groups in any of the variables that were examined (p > 0.05) except that the high-Dk lens wearing group had about twofold more tear film debris and 2.5-fold more severe conjunctival staining (p < 0.05). Conclusions. Hypoxia-associated effects were not apparent in the eyes of subjects wearing experimental high-Dk soft contact lenses. Conjunctival staining can generally distinguish lens wearers from non–lens wearers and can be used to discriminate between high-Dk lens wearing subjects and non–lens wearing subjects.

Superior epithelial arcuate lesions with soft contact lens wear.

Background Superior epithelial arcuate lesions (SEALs) are an infrequent and often asymptomatic complication of conventional soft contact lens wear. The characteristic arcuate pattern of the full-thickness corneal epithelial lesion usually occurs in the area covered by the upper eyelid, within 2 to 3 mm of the superior limbus in the 10- and 2-o’clock region. Methods Literature on SEALs and recent clinical records from clinical trials using two types of prototype high Dk soft contact lenses were reviewed to gain greater insights into the etiology of SEALs. Results and Conclusions The reported low incidence of SEALs is partly because SEALs are not usually symptomatic. The etiology of SEALs is multifactorial. Our current hypothesis is that SEALs are produced by mechanical chaffing at the peripheral cornea. This chaffing occurs as a result of inward pressure of the upper lid, in an area where the peripheral corneal topography and lens design, rigidity, and surface characteristics combine to create excessive “frictional” pressure and abrasive shear force on the epithelial surface. Patient characteristics such as gender, age, and specific corneal and lid topographies also appear to influence the occurrence of SEALs. Prototype silicone hydrogel lenses are made from higher modulus materials with surfaces that seem to differ subtly in wettability in some patients. The prevalence of SEALs may well increase with the first generations of these lenses.

Clinical characterization of corneal infiltrative events observed with soft contact lens wear.

Purpose. Corneal infiltrates are commonly observed during adverse reactions associated with contact lens wear. Broad ranges of presentations are encountered, and there is no well-established classification system. The aim of this paper is to categorize corneal infiltrates associated with soft lens wear and present the typical clinical characteristics associated with each type of event. Methods. All events of corneal infiltrates occurring in soft contact lens clinical trials over 10 years (9 years retrospective and 1 year prospective) and conducted at two contact lens research centers were reviewed by a panel of experts comprising ophthalmologists, optometrists, and other biologic scientists. Classification of each event was based on assessment of a range of signs and symptoms by the review panel. Results. A classification scheme was devised to distinguish infiltrative events that were serious and symptomatic (microbial keratitis), clinically significant and symptomatic (contact lens–induced peripheral ulcer, contact lens–induced acute red eye, infiltrative keratitis), and clinically nonsignificant and asymptomatic (asymptomatic infiltrative keratitis and asymptomatic infiltrates). Conclusion. Corneal infiltrates can be classified into six distinct categories. This classification scheme, based on clinical characteristics, should aid diagnosis, management, and treatment of corneal infiltrates as well as assisting investigations into the etiology of each of these conditions.

Adverse events with extended wear of disposable hydrogels: results for the first 13 months of lens wear

OBJECTIVE To determine the type and incidence of adverse events seen in the first 13 months of extended wear from a prospective clinical trial involving the use of disposable hydrogels on a 6-night extended wear and replacement schedule. DESIGN A prospective, noncomparative clinical trial. PARTICIPANTS Three hundred thirty subjects were enrolled in the study from March 1993 to August 1996 and commenced in extended wear. The subjects were new contact lens users with ages ranging from 16 to 39 years and refractive errors from -1.00 to -6.50-diopter (D) sphere with cylindrical component less than 1.0 D. INTERVENTION Disposable hydrogel lenses on a 6-night extended wear and replacement schedule. MAIN OUTCOME MEASURES To determine the incidence of adverse events in the first 13 months of lens wear with the use of disposable hydrogels on an extended wear schedule. In addition, corneal infiltrative events observed with lens wear were classified based on their presenting signs and symptoms. RESULTS A total of 137 adverse events were seen in 102 subjects in the first 13 months of extended wear. The type of adverse events and the incidence per 100 patients per year of lens wear were as follows: corneal infiltrative events (44.4 events), contact lens papillary conjunctivitis (6.4 events), neovascularization and corneal wrinkling (1.7 events each), corneal striae and superior epithelial arcuate lesions (1.3 events each), and blepharokeratoconjunctivitis (0.4 event). Viral keratoconjunctivitis was also observed (0.8 event). The corneal infiltrative events were further subclassified as follows: contact lens-induced peripheral ulcers (13.6 events), contact lens-induced acute red eyes (12.3 events), infiltrative keratitis (9.7 events), and asymptomatic infiltrative events (8.9 events). There were no events of infectious keratitis. Except for all events of contact lens-induced peripheral ulcers and two isolated events of infiltrative keratitis that resulted in scarring, all of the corneal infiltrative events resolved without sequelae. None of the events caused any loss of best-corrected visual acuity. CONCLUSIONS Based on the observations from the first 13 months of extended wear in the trial, the majority of the complications associated with extended wear of disposable hydrogels are corneal infiltrative events. No events of microbial keratitis were seen in the first 13 months of extended wear. None of the events were associated with loss in best-corrected visual acuity. Clearly, frequent and regular disposing of lenses does not eliminate adverse effects, and better materials and designs are required for extended wear to be a successful method.

In Vivo Performance of Melimine as an Antimicrobial Coating for Contact Lenses in Models of CLARE and CLPU

PURPOSE One strategy to minimize bacteria-associated adverse responses such as microbial keratitis, contact lens-induced acute red eye (CLARE), and contact lens induced peripheral ulcers (CLPUs) that occur with contact lens wear is the development of an antimicrobial or antiadhesive contact lens. Cationic peptides represent a novel approach for the development of antimicrobial lenses. METHODS A novel cationic peptide, melimine, was covalently incorporated into silicone hydrogel lenses. Confirmation tests to determine the presence of peptide and anti-microbial activity were performed. Cationic lenses were then tested for their ability to prevent CLPU in the Staphylococcus aureus rabbit model and CLARE in the Pseudomonas aeruginosa guinea pig model. RESULTS In the rabbit model of CLPU, melimine-coated lenses resulted in significant reductions in ocular symptom scores and in the extent of corneal infiltration (P < 0.05). Evaluation of the performance of melimine lenses in the CLARE model showed significant improvement in all ocular response parameters measured, including the percentage of eyes with corneal infiltrates, compared with those observed in the eyes fitted with the control lens (P < or = 0.05). CONCLUSIONS Cationic coating of contact lenses with the peptide melimine may represent a novel method of prevention of bacterial growth on contact lenses and consequently result in reduction of the incidence and severity of adverse responses due to Gram-positive and -negative bacteria during lens wear.

Peripheral defocus with single-vision spectacle lenses in myopic children.

Purpose. To determine the impact of wearing single-vision spectacle lenses (SVLs) on the refractive errors at the periphery of the retina in myopic eyes of Chinese children. Methods. Twenty-eight children (8 to 15 years) were divided into two groups: one (n = 17) comprising children with low myopia (spherical equivalent between −0.75 D and −3.00 D inclusive) and the other (n = 11), with moderate myopia (spherical equivalent between −3.25 D and −6.00 D inclusive). Cycloplegic autorefraction from right eyes was measured at the fovea and at 20, 30, and 40° in the temporal and nasal visual fields. Measurements were taken on each subject both while uncorrected and while wearing SVLs. Results. Hyperopic peripheral defocus was found with SVLs in both the low and moderate myopia groups. However, the increase in relative peripheral hyperopic defocus when wearing spectacle correction, when compared with the uncorrected state was statistically significant for the moderate myopia group only. In the moderate myopia group, relative peripheral hyperopic defocus when wearing spectacle correction was statistically significantly greater vs. the low myopia group at 40° in the nasal field and at both 30 and 40° in the temporal field (p < 0.038). An increase in astigmatism with correction was observed for J45 (p < 0.05) was also seen in eyes with moderate myopia, but this was limited to the nasal field. Conclusions. Previous investigators have suggested that peripheral hyperopic defocus may play a role in the development and progression of myopia. We have shown that SVLs used to correct myopia can result in increased hyperopic defocus at the peripheral retina in the eyes of Chinese children. The magnitude of this increase tends to escalate with increasing refractive error and eccentricity, especially in cases with moderate levels of myopia.

Myopia, an underrated global challenge to vision: where the current data takes us on myopia control

Myopia is the most frequent cause of distance impairment in the world and is creating an alarming global epidemic with deleterious ramifications for the quality of life and economic health of individuals and nations as a whole. In addition to being immediately disadvantageous, myopia increases the risk of serious disorders such as myopic macular degeneration, retinal detachment, glaucoma, and cataract and is a leading cause of visual impairment and blindness across many countries. The reduction in age of onset of myopia is of great concern since the earlier the onset, the more myopic the individual will become, with all the attendant increased risks of accompanying debilitating eye conditions. The economic burden is great; both in consequences of uncorrected refractive error and also in the provision of devices for correcting visual acuity. Earlier onset of myopia increases the lifetime economic burden related to loss of productivity and independence, leading to a reduced quality of life. Recent data suggest addressing accommodation per se has little direct amelioration of myopia progression. Pharmacological interventions that effect changes in the sclera show promising efficacy, whereas optical interventions based on a myopic shift in the retinal image are proving to effect up to 55% reduction in the rate of progression of myopia. Early contact lens and spectacle interventions that reduce the rate of progression of myopia are able to significantly reduce the burden of myopia. These non-pharmacological interventions show profound promise in reducing the overall associated morbidity of myopia.

Microbial keratitis and vision loss with contact lenses.

Purpose. Microbial keratitis is the only sight-threatening adverse event that occurs with contact lens wear. This article gives a preliminary estimation of the incidence of microbial keratitis and vision loss with continuous-wear contact lenses made from highly oxygen permeable (Dk) materials. Methods. The most up-to-date data available on microbial keratitis and vision loss are collected from a range of sources including industry, private practice, and publications and is reviewed. Results. There have been 16 cases of microbial keratitis with high-Dk silicone hydrogel lenses. Of the 13 where data are available, none have lost two or more lines of best-corrected visual acuity (BCVA). Conclusion. First approximation indicates that the incidence of microbial keratitis with high-Dk silicone hydrogel lenses may be lower than the incidence with low-Dk soft lenses during extended wear. The rate of loss of more than two lines of BCVA is low in patients that develop microbial keratitis with low- and high-Dk soft lenses.