Ocular protection by contact lenses from mechanical trauma

Many lost-time industrial eye injuries are due to small highspeed particles striking the cornea. To investigate whether contact lenses would complicate such injuries, we exposed porcine eyes fitted in vitro with rigid, hydrogel, or no contact lens to iron filings suspended in a high-speed air jet. Postexposure evaluations of 11 control eyes and 23 contact lens-wearing eyes revealed more extensive and severe corneal damage in the control group. Of the 23 contact lens-wearing eyes, fewer and less severe corneal injuries were observed among those wearing rigid lenses. Contact lenses do not increase the risk of corneal injury due to small high-speed particles striking the eye; instead, they provide additional protection from mechanical injury.     

Variables affecting rigid contact lens comfort in the collaborative longitudinal evaluation of keratoconus (CLEK) study.

PURPOSE: To identify factors associated with rigid contact lens comfort in keratoconus. METHODS: Baseline data from the 16 Collaborative Longitudinal Evaluation of Keratoconus (CLEK) Study clinical sites were analyzed for all patients wearing a rigid contact lens in their more severely keratoconic eye (as determined by steep keratometry). Corneal transplant patients, patients who did not wear a rigid contact lens in either eye, patients who did not wear a rigid lens in their worse eye, and patients with missing contact lens comfort data were excluded from the sample. A total of 751 eyes were included. Variables assessed included measures of disease severity, visual acuity through the patients' habitual rigid contact lenses, contact lens wearing time, the apical fitting relationship of the contact lens, the degree of peripheral clearance, and the presence of corneal scarring and staining. Comfort was measured by asking the patients "In general, how comfortable are your contact lenses?" (1 = very comfortable through 5 = very irritating). RESULTS: Measures of disease severity (steep keratometry and the first definite apical clearance lens) were not associated with lens comfort. There was no difference in self-reported contact lens comfort between patients fitted with apical touch vs. apical clearance. Patients with a peripheral clearance rating of "minimal unacceptable" (more common among patients with milder keratoconus) were approximately half as likely to report good contact lens comfort compared with patients with "average" peripheral clearance (unadjusted odds ratio, 0.39; 95% confidence interval, 0.19 to 0.79). There was no association between contact lens comfort and the other peripheral clearance ratings compared with ratings of average. CONCLUSIONS: There does not appear to be an association between decreasing patient-reported rigid lens comfort and increasing disease severity as measured by steep keratometry or first definite apical clearance lens in this sample. The apical fitting relationship (flat vs. steep) does not appear to be associated with patient-reported comfort. Minimal peripheral clearance may contribute to decreased rigid contact lens comfort in keratoconus.     

Corneo-scleral rigid gas permeable contact lens prescribed following penetrating keratoplasty

Corneo-scleral rigid gas permeable lenses represent a new category of contact lens. Incorporating an overall diameter of approximately 14 to 15 mm, the corneo-scleral lens is larger than a corneal lens yet smaller than a scleral lens. A 39-year-old man was referred to our office for a contact lens fitting following penetrating keratoplasty of the left eye for advanced keratoconus. The patient was successully prescribed a corneo-scleral contact lens for the left eye.     

Topography-guided excimer laser ablation of irregular cornea resulting from penetrating injury.

A 26-year-old woman with irregular astigmatism caused by ocular perforation became aphakic in the injured left eye 2 years after the initial trauma. The initial corneoscleral wound repair was performed without intraocular lens implantation. The patient's uncorrected visual acuity in the right eye was 20/20 and in the left eye, counting fingers at 50 cm. The vision in the left eye could not be corrected with a spectacle because of high corneal astigmatism so a rigid gas-permeable contact lens was tried. With a contact lens, the acuity improved to 20/80; however, the patient could not wear the lens because of intolerance and severe astigmatism. As an alternative, topography-guided ablation was performed to correct the corneal astigmatism. Treatment of the irregular central cornea reduced the astigmatism. Three months postoperatively, the corrected visual acuity was 20/20 with a refraction of +8.00 -1.50 x 26. This case indicates that topography-guided ablation can be a useful surgical method for correcting surgically induced irregular astigmatism.     

Tear plasmin activity with contact lens wear.

Plasmin, a proteolytic enzyme, has been detected in the tears of patients experiencing anterior ocular disease, and during contact lens wear. Using a radial caseinolysis procedure, we examined tear plasmin levels in 66 patients who were wearing soft and rigid lenses for daily and extended wear. Compared to non-contact lens wearers, patients wearing soft and rigid lenses for extended wear were significantly more likely to exhibit tear plasmin activity. Eight hours of open-eye thick HEMA lens wear did not induce tear plasmin activity in a group of 10 subjects. However, significant increases in tear plasmin activity were recorded after short-term (1 hour) eye closure with and without lens wear, and following overnight (8 hours) eye closure without lens wear. Overnight eye closure also resulted in significantly increased numbers of epithelial cells and leucocytes in the tear fluid. Our results suggest that increased tear plasmin activity during extended contact lens wear may be attributable to the effects of eye closure rather than hypoxia or the presence of the contact lens per se.     

Serratia Marcescens corneal ulcer as a complication of orthokeratology

PURPOSE: To report a case of Serratia Marcescens corneal ulcer as a complication of orthokeratology treatment. METHODS: Case report. RESULTS: A 9-year-old male who underwent orthokeratology treatment for 6 months suffered from a corneal ulcer. The refractive state of lesion eye was -5.5D/-1.25D x 180 degrees, and visual acuity was hand motion at 30 cm. He wore a retainer lens, rigid gas permeable lens, overnight for 2 months before the corneal ulcer occurred. Ulcer became worse after tobramycin and gentamycin treatment for 2 days. After ciprofloxacin treatment, the ulcer healed and visual acuity recovered to 20/20 with spectacle correction. Cultures of the cornea tissue and contact lens storage solution both grew Serratia Marcescens, which was sensitive to ciprofloxacin. CONCLUSION: Overnight wearing of a rigid contact lens is a risk factor for a corneal ulcer.     

The contact lens and myopia progression (CLAMP) study: design and baseline data.

BACKGROUND: Although previous contact lens myopia control studies indicate that rigid contact lenses slow the progression of myopia in children, they have all suffered from limitations that challenge the significance of their results. The Contact Lens and Myopia Progression (CLAMP) Study addresses the limitations of previous studies and attempts to correct them by implementing alternative Study designs. The CLAMP study also measures all the ocular components to examine the potential mechanism of treatment effect. METHODS: Eligible children were fitted with rigid gas-permeable contact lenses and enrolled in a run-in period to determine whether they were able to adapt to rigid contact lens wear. Subjects who successfully completed the run-in period were randomly assigned to wear rigid contact lenses or soft contact lenses for the remainder of the 3-year study. The primary outcome measure will be the 3-year change in cycloplegic autorefraction; the secondary outcome measures will include the 3-year change in axial length, peripheral autorefraction, crystalline lens curvatures, corneal curvature and thickness, accommodation, and intraocular pressure, which are being measured annually. RESULTS: We examined 148 eligible subjects who participated in the run-in period. Of the 148 eligible subjects, 116 (78.4%) were able to adapt to rigid contact lens wear and were enrolled in the CLAMP Study. The mean age of the participants at the baseline visit was 10.5 years, and 59.5% were girls. At the randomization visit, the mean (+/-SD) spherical equivalent refractive error in the right eye was -2.09 +/- 0.89 D, the mean central curvature of the right cornea by videokeratography was 44.5 +/- 1.3 D, and the mean axial length of the right eye was 24.13 +/- 0.71 mm. CONCLUSIONS: Four of five children aged 8- to 11-years-old were able to adapt to rigid gas-permeable contact lens wear. The CLAMP Study aims to further clarify the effect of rigid gas-permeable contact lenses on myopia progression in children.     

Visual rehabilitation after severe alkali injury with piggyback hyper O2 contact lenses

PURPOSE: To report successful visual rehabilitation following severe bilateral alkali injury using piggyback hyperoxygen-transmissible (hyper O2) contact lenses. METHODS: Case report and literature review. RESULTS: More than 15 years after a severe bilateral alkali injury, multiple surgical procedures including repeat bilateral penetrating keratoplasty, severe tear deficiency, and chronic ocular surface disruption, the patient achieved 20/30 best-corrected vision through the simultaneous use of a hyper O2 rigid gas permeable contact lens over a hyper O2 soft contact lens in his right eye. The patient has tolerated this piggyback combination without any adverse reactions or complications, and his corneal graft remains clear and healthy. CONCLUSION: Visual rehabilitation for conditions that compromise the ocular surface can be accomplished by utilizing newer soft and rigid contact lens materials that facilitate oxygen transmission, thereby promoting epithelial healing and improving safety in extended wear situations. These newer materials may potentially reduce complications previously associated with extended wear therapeutic lenses.     

Rigid contact lens fitting relationships in keratoconus. Collaborative Longitudinal Evaluation of Keratoconus (CLEK) Study Group.

PURPOSE: Although the influence of flat-fitting contact lenses on corneal scarring in keratoconus is frequently debated, the current standard of care with regard to the apical fitting relationship in keratoconus remains undocumented. METHODS: Patients were examined at baseline in the Collaborative Longitudinal Evaluation of Keratoconus (CLEK) Study (N = 1209). Patients wearing a rigid contact lens in one or both eyes (N = 808) had their habitual rigid contact lenses analyzed, and the fluorescein patterns and base curves were compared to the first definite apical clearance lens (FDACL). The FDACL is the flattest lens in the CLEK Study trial lens set that exhibits an apical clearance fluorescein pattern. For patients wearing a rigid contact lens in both eyes, one eye was selected randomly for analysis. RESULTS: Twelve percent of the rigid contact lens-wearing eyes were wearing lenses fitted with apical clearance based upon the clinician's fluorescein pattern interpretation. The remainder (88%) was wearing lenses fitted with apical touch. For mild (steep keratometric reading <45 D) keratoconus corneas, the mean estimate of the base curve to cornea-fitting relationship was 1.18 D flat (SD +/- 1.84 D); moderate (steep keratometric reading: 45 to 52 D) corneas were fitted on average 2.38 D flat (SD +/- 2.56 D); and severe (steep keratometric reading > 52 D) corneas were fitted an average of 4.01 D flat (SD +/- 4.11 D). CONCLUSIONS: Despite the potential risk for corneal scarring imposed by flat-fitting rigid contact lenses, most CLEK Study patients wear flat-fitting lenses. Overall, rigid lenses were fitted an average of 2.86 D (SD +/- 3.31 D) flatter than the FDACL.     

Significance of the study of the pachymetric index in the evaluation of the process of eye adaptation to contact lenses

The authors have examined the thickness of the cornea in 270 patients with weak and moderate myopia during adaptation of the eye to soft or rigid contact lenses. They have revealed a linear correlation between the period of wearing the lens and the degree of the pachometric index change during adaptation of the eye to contact lenses. The maximum permissible period for daily wearing of contact lenses have been determined, not involving essential shifts in water-salt metabolism of the cornea. Optimal schedules for managing the adaptation process with rigid and soft contact lenses have been developed, based on the regularities of the corneal thickness changes related to the length of the lens wearing.     

Corneal trauma from overnight wear of rigid or soft contact lenses.

To evaluate the mechanical or biochemical insult to the cornea induced by overnight rigid gas permeable (RGP) or soft contact lens (SCL) wear, punctate, stipple staining and corneal blotting were evaluated by biomicroscopy in a group of 23 subjects who participated in a single overnight in-laboratory test session. The soft lens-wearing corneas typically showed greater area of staining along with corneal blotting in comparison to RGP-wearing corneas which showed smaller areas of corneal staining, even in the presence of RGP adherence, and no corneal blotting. We investigated the effect of hypoxia on corneal staining by having subjects wear an RGP lens of Dk = 150 on one eye and a soft lens of Dk = 9 on the fellow eye. Pachometry measurements immediately following eye opening showed an average central corneal swelling of 5 percent for the RGP lens-wearing eye and an average of 11 percent for the SCL-wearing eye. It is likely that the differences in corneal effects of RGP and SCL overnight lens wear are the result of differences in the nature of rigid versus soft contact lens adherence.     

Conjunctival histologic findings of dry eye and non-dry eye contact lens wearing subjects.

PURPOSE: To determine if contact lens wearers with dry eye (DE CL) have greater histological and inflammatory conjunctival epithelial changes compared to non-dry eye contact lens wearers (CL). METHODS: Fifty-eight myopic subjects were recruited for the study: DE CL group (N=27), CL group (N=11), and control group (N=20). Contact lens groups were matched for proportions of rigid gas permeable (RGP) lenses, disposables, and conventional soft contact lenses. Dry eye was defined by McMonnies dry eye symptom survey score of > or =14, fluorescein break up time (FBUT) of <10 seconds, and the presence of rose bengal staining. Ocular surface samples were taken using conjunctival impression cytology to determine nucleo-cytoplasm ratio, goblet cell density (GCD), and expression of conjunctival antigens to HLA DR and CD23. RESULTS: HLA DR and CD23 expression were significantly greater for the DE CL group compared to the CL group (P=0.0122 and P=0.0072, respectively). The CL group had a significant reduction in GCD (P=0.0001), and greater expression of ocular surface antigens to HLA DR (P=0.04) and CD23 (P=0.04) compared to the control group. CONCLUSIONS: The results of this study support the view that mechanical influences are responsible for the conjunctival squamous metaplasia changes in contact lens wear. Dry eye in contact lens wear is associated with allergic and immune mediated inflammatory processes.     

Retinal detachment due to a retinal break in the macular atrophy of a myopic choroidal neovascularization.

In a case of rhegmatogenous retinal detachment in a highly myopic eye, repeated optical coherence tomography revealed a small break around the scar tissue of a myopic choroidal neovascularization that was difficult to observe with conventional slit-lamp examination using a contact lens due to severe chorioretinal atrophy. This article presents the optical coherence tomography findings of the retinal detachment before and after the treatment and discusses the pathologic role of myopic choroidal neovascularization in the retinal detachment.     

Acute ptosis secondary to contact lens wear.

Ocular ptosis secondary to the wearing of rigid contact lenses has been reported. Generally this ptosis is not of the classical variety, and appears to be an edematous or inflammatory response of the lid to the presence of the lens. We report a case of acute ptosis secondary to rigid lens wear in a patient who had undergone cataract surgery. The patient had been a contact lens wearer before surgery, and developed the relative ptosis postsurgically in the nonoperated eye. The ptosis resolved without any form of intervention other than ceasing to wear the contact lens. We feel that in cases where rigid lens wear is discontinued unilaterally for any reason, and a relative ptosis is noted, it should be given time to resolve before any therapeutic regimen is considered.     

Correction of astigmatism with rigid gas permeable lenses

Comparison of the results of keratometry and refraction usually suggests the appropriate contact lens for a patient's eye. Specialized rigid toric contact lenses include bitoric and back toric RGP lenses, front toric RGP lenses, and bitoric RGP lenses with prism ballast. Each lens has specific indications.     

Vision-specific quality of life and modes of refractive error correction.

PURPOSE: Many studies currently use surveys to assess patients' reports of vision-specific quality of life to determine the impact of the disease or the most appropriate mode of treatment. One such instrument, the National Eye Institute Visual Function Questionnaire (NEI-VFQ), was developed to assess vision-related quality of life with respect to emotional well-being and social function as well as difficulty with tasks and symptoms. We administered the NEI-VFQ to 218 subjects free of eye disease to see if the survey was sensitive enough to detect differences in three modes of refractive error correction: spectacles, soft contact lenses, and rigid contact lenses. METHODS: Surveys were administered to 117 rigid contact lens wearers, 51 spectacle wearers, and 50 soft contact lens wearers. Kruskal-Wallis one-way analysis of variance was conducted to determine significant differences in each of the subscales. RESULTS: The Peripheral Vision subscale score (mean +/- SD) was 92.6 +/- 15.2 for the spectacle wearers, 100.0 +/- 0.0 for the soft contact lens wearers, and 98.3 +/- 7.1 for the rigid gas-permeable contact lens wearers; the spectacle wearers' Peripheral Vision score was significantly lower than the other two groups (Wilcoxon rank sum, p < 0.003 for both). The spectacle wearers (96.6 +/- 9.2) also had a significantly lower Dependency subscale score than the rigid contact lens group (99.7 +/- 1.5) (Wilcoxon rank sum, p = 0.001). There were no significant differences between the three groups detected in the mean of any of the other subscale scores. At least 50% of the subjects reported the maximum score for 6 of the 11 subscales. Given our sample size, we have 100% power to detect a difference of 10 points with a SD of 10 at the alpha = 0.05 level. CONCLUSION: The NEI-VFQ is not appropriate for detecting significant differences in vision-related quality of life among spectacle, soft contact lens, and rigid gas-permeable contact lens wearers, primarily due to maximum ratings by many of the subjects.     

Rose-K contact lens for keratoconus

AIM: To report clinical experience and the comparative value of axial and instantaneous topography data in fitting Rose-K design contact lenses in moderate and severe keratoconus. MATERIALS AND METHODS: Thirty-eight eyes (of 23 patients) with keratoconus were fitted with Rose-K design contact lenses and followed up for at least six months or more. Visual acuity with habitual vision correction available was measured. Axial and instantaneous topography maps for each eye were recorded. Contact lens wear comfort was graded on a ten point rating scale every three months. RESULTS: Fourteen (100%) moderate keratoconus eyes (average Sim K 48.61 +/- 1.24D) and 23 of 24 (96%) of severe keratoconus eyes (average Sim K 60.88 +/- 5.31D) were successfully fitted with the Rose-K lenses. Final fit contact lenses in severe keratoconus had statistically significant steeper base curves compared to average axial corneal curvature than in moderate keratoconus eyes. Average simulated corneal curvature on axial maps predicted final fit contact lens base curves significantly better than on instantaneous maps. Thirty-three of the 37 eyes fitted with contact lenses maintained wear comfort over average follow up period of 13 +/- 3.5 months. CONCLUSIONS: Rose-K design rigid contact lenses are successful in visually rehabilitating 100% of moderate and 96% of severe keratoconus eyes. Most patients (90%) maintained contact lens wear comfort. Corneal curvature on axial maps is a better predictive of base curve of final fit contact lens.     

Rigid contact lens adherence: incidence, severity and recovery

The incidence of rigid lens adherence in one eye of 25 subjects was compared to the results for the fellow eye wearing a soft lens of nearly equal permeability in an in-laboratory overnight study. A 48% incidence of adherence was found for both extended wear modalities, which demonstrates the high frequency of this problem. Adherence of both rigid and soft lenses caused epithelial breakdown and corneal distortion, but these sequelae were generally more severe with rigid lenses. Recovery data on nine subjects whose rigid lenses adhered show that positive signs of adherence often disappear within 1 hour, demonstrating the need for early morning examinations. Practical considerations for the detection of rigid lens adherence and the possible consequences of failure to diagnose this condition are discussed.     

On-eye evaluation of optical performance of rigid and soft contact lenses.

A Shack-Hartmann aberrometer was used to assess the optical performances of eyes corrected with rigid or soft contact lenses compared with spectacles. Metrics of optical quality derived from the measured wave aberrations were consistent with the subjective rating of visual clarity by subjects. Optical aberration analysis illustrated the differences in aberration structures of eyes wearing different optical corrections. For our subjects, correction with a rigid gas-permeable lens yielded significantly better optical quality than did the soft contact lens or spectacle lens. This was due to a reduction in the eye's asymmetric (odd-order) aberrations and a reduction in the amount of the eye's positive spherical aberration. These observations can be explained by theoretical calculations of the aberrations of the eye plus lens optical system. We conclude that aberrometry provides a better understanding of the optical effects of contact lenses in situ and could be useful for optimizing future designs of contact lenses.