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Purpose: To highlight the potential benefits for long-term use of silicone hydrogels daily disposable (DD) contact lenses, particularly with patients who are noncompliant, sleeping or napping while wearing their lenses, or those who have higher oxygen demands and wear this modality for decades., Methods: Published data for corneal swelling with lenses and no lens wear were used to develop a nonlinear least squares model. The edema load experienced with a range of oxygen transmissibilities (Dk/t) and wear compliance (sleep and napping) was determined. A mixed-effects linear regression model was used to compare the edema load for high and average corneal swellers., Results: The edema load generated demonstrates that a high Dk/t silicone hydrogel lens results in edema levels close to that with no lens wear. In comparison, hydrogels with a Dk/t of 27 (× 10-9 [cm mL{O2}][s mL mm Hg]), worn on a daily wear schedule will result in 1.5 times more edema and up to two times more if the patient is noncompliant over each decade of wear. High swellers after four decades of wear will have an edema load 10 to 17 times greater than average swellers depending on Dk/t and their degree of noncompliance with the daily wear modality., Conclusions: Prescribing silicone hydrogel DD lenses, particularly with higher DK/t, may help to maintain the long-term ocular health of patients, when they wear their lenses fulltime for many decades., Translational Relevance: Illustrates the importance of Dk/t for any CL wear modality where patients nap or sleep in lenses or have high oxygen needs.

Lack of or inadequate hand washing is a risk factor in the development of contact lens related microbial keratitis and corneal inflammatory events. In the public health domain there is compelling evidence that proper hand washing with soap can save lives. The purpose of this review is to draw attention to some of the public health literature in support of hand washing and how education can influence patients' hand hygiene behavior. Contact lens wearers are also guilty of poor hand washing behavior but there is scant evidence that education of hand washing procedures of lens wearers alters patient non-compliance. It is well known that pathogenic microbial contamination of contact lenses, lens cases, care solutions and anterior ocular components have been found with contact lens wear. However while the originating source may be hands or water, it is most likely both of these. Besides proper hand washing this paper will include mitigating strategies for avoiding microbial contamination., (Copyright © 2018 British Contact Lens Association. Published by Elsevier Ltd. All rights reserved.)

Objectives: Discontinuation or "dropout" from contact lens (CL) wear continues to afflict the CL industry. This study was conducted to determine whether the advent of new CL materials and designs has impacted the dropout rate and the reasons for discontinuation., Methods: Current and lapsed CL wearers residing in Canada were recruited using Facebook to take part in an on line survey investigating CL wearing experiences during 2008 to 2010 and to establish the percentage of participants who temporarily and permanently discontinued CL wear during the period surveyed., Results: Four thousand two hundred seven eligible surveys were received (64% female; median age 27 years). Forty percent had lapsed from lens wear for at least 4 months; however, 62% of the lapsed wearers (LWs) resumed wear. There were no differences between LWs and nonlapsed wearers (NLWs) with respect to gender; however, LWs were older, started lens wear when older, and had not worn lenses for as long as NLWs (all P<0.001). More NLWs than LWs wore silicone hydrogel CLs (49% vs. 38%, P<0.001) and more LWs than NLWs wore daily disposable lenses and hydrogel CLs (24% vs. 19% and 22% vs. 18%, respectively, P≤0.001). Primary reasons for discontinuation were discomfort (24%), dryness (20%), red eyes (7%), and expense (7%). Compliance with lens replacement was no different between LWs and NLWs (48% vs. 45%)., Conclusions: About 23% of those surveyed had discontinued CL wear permanently. The primary reasons for dropping out continue to be discomfort and dryness. Dropout rates were lower in silicone hydrogel wearers.

Purpose: Corneal vasculature change in contact lens wearers has been linked to the level of hypoxia within the cornea.To assess the impact a treatment has on limbal vessels, a sensitive method of measurement and quantification is required., Methods: A group of 21 highly myopic, hydrogel wearers, with preexisting signs of corneal hypoxia, were enrolled into a study where they wore sifilcon A penetrated hydrogel lenses (Dk/t ± 117), on a daily wear basis for 9 months. At all scheduled visits, photographs were taken of the superior, inferior, temporal, and nasal limbal regions which were then imported into Adobe Photoshop. A red-free filter was applied to enhance the contrast of the blood columns. In each quadrant, the length of the longest visible blood column was measured and the blood columns that penetrated 0.5 mm into the cornea were counted. A control group of 11 non-lens wearers was recruited. Their photographs were taken at the beginning of the study and 9 months later. An independent, masked observer assessed the photographs., Results: There was a significant decrease in the maximum penetration of the blood column in all quadrants (p = 0.001) from baseline to the 9-month visit (e.g., superior: baseline 0.84 ± 0.39 mm; 9 months 0.63 ± 0.20 mm). There was also significant reduction in the number of visible blood columns longer than 0.5 mm in each quadrant (p = 0.001) from baseline to 9 months in all quadrants (e.g., superior: baseline 14.0 ± 8.2; 9 months 6.5 ± 6.0). The control group showed no change over time for the maximum blood column length (p = 0.638) or the number of columns 0.5 mm (p = 0.341)., Conclusions: A group of highly myopic subjects exhibited reduction in the maximum length and number of blood columns in the cornea when ref it with a highly permeable silicone hydrogel material. The use of photography, along with Adobe Photoshop software, provides a reliable way of measuring corneal vascular responses over time.

Objective: To review the effects of contact lenses on the corneal surface., Methods: A review of the literature and in-house research of corneal staining and its various forms of presentation., Results: Corneal staining manifests in many different forms. The severity of staining or insult of the cornea is usually determined by the extent (area of coverage), density, and depth. The cause of staining is multifactorial, and its location is often linked to the type of lens that is being worn, the solution used to clean/disinfect the lens, the state of hydration of the soft lens, and the state of the cornea that has been affected by the lens., Conclusions: Sodium fluorescein dye effectively highlights corneal integrity changes referred to as corneal staining. This review describes the manifestations, the cause, the mechanisms, and the methods of remediation of corneal staining.

Purpose: To investigate changes in epithelial thickness after overnight wear of CRTH rigid gas-permeable (RGP) lenses (Paragon Vision Sciences, Mesa, AZ) for the correction of hyperopia., Methods: Twenty subjects wore a +3.50 D hyperopia-correcting CRTH lens on one eye for a single night in an attempt to induce myopia (first study). The untreated eye served as the control. Corneal and epithelial thickness was measured at nine points across the horizontal meridian by OCT. Measurements were obtained the night before lens wear, immediately after lens removal the next morning, and 1, 3, 6, and 12 hours after removal. Measurements were obtained 28 hours later, to observe recovery. Then, the attempted hyperopic corrections of +1.50 and +3.50 D were evaluated, using CRTH lenses in both eyes of 20 subjects for a single night (second study)., Results: All values were compared to baseline unless otherwise stated. In the first study, the treated eye's central and midperipheral epithelial thickness increased by 21.5% +/- 8.6% and 13.3% +/- 7.6%, respectively, after lens removal (P < 0.001). The control eye's central epithelial thickness (CET) increased by 7.1% +/- 6.0% (P < 0.05). In the second study, CET increased by 17.6% +/- 8.5% (P < 0.001) in the +3.50 D-treated eye and by 13.3% +/- 4.8% (P < 0.001) in the +1.50 D-treated eye. Midperipheral epithelial thickening was 5.9% +/- 4.7% (P < 0.05) in the +3.50 D-treated eye and 6.0% +/- 6.3% (P < 0.05) in the +1.50 D-treated eye., Conclusions: CRTH lenses, designed to correct hyperopia, when worn overnight, caused an increase in CET. The amount of epithelial change seemed to differ with modified lens design.

Purpose: To determine the malleability of the ocular surface by examining the acute effects of local mechanical stress on optical performance, corneal shape, and corneal/epithelial thickness after corneal refractive therapy for myopia and hyperopia (CRT and CRTH)., Methods: Twenty ametropes (spherical equivalent: -2.08 +/- 2.31 D) wore CRT and CRTH lenses in a random order on 1 eye (randomly selected). The lenses were worn for 15, 30, and 60 minutes (randomly ordered, with each period taking place on a different day). Refractive error, aberrations, corneal topography, and corneal/epithelial thickness (using OCT) were measured before and after lens wear. The measurements were performed on the control eyes at the 60-minute visit only., Results: With both CRT and CRTH lens wear, significant changes occurred in many parameters from the 15-minute time point. The refractive error and defocus decreased after CRT lens wear (all P < 0.05) and increased after CRTH lens wear from baseline (all P < 0.05). Astigmatism did not change (both P > 0.05). Higher-order aberrations, including coma and spherical aberration (SA), increased after CRT and CRTH lens wear (all P < 0.05) from baseline, but the signed SA shifted from positive to negative after CRTH lens wear (P < 0.05). The central cornea flattened and the midperiphery steepened after CRT lens wear, whereas the central cornea steepened and paracentral region flattened after CRTH lens wear (P < 0.05). The central cornea swelled less than the midperiphery after CRT lens wear (P < 0.05), whereas the central cornea swelled more than the paracentral region after CRTH lens wear (P < 0.05). The central epithelium was thinner than the midperiphery after CRT lens wear (P < 0.05) and thicker than the paracentral region after CRTH lens wear (P < 0.05). Optical performance, corneal curvature, and epithelial thickness did not change from baseline in the control eyes (all P > 0.05)., Conclusions: CRT lenses for myopia and hyperopia induce significant structural and optical changes in as little as 15 minutes. The cornea, particularly the epithelium, is remarkably malleable, with rapid steepening and flattening possible in little time.

Contact lenses can affect the cornea in a variety of ways. Corneal structure can be altered so that its thickness changes to involve the epithelium and the stroma. As a result, the curvature may be affected, but whether it is the front or the back surface that is affected depends on the type of lens used. If thickness increases sufficiently, corneal transparency may decrease. Contact lenses can also affect cellular structure of all layers of the cornea through mechanical trauma, hypoxia, or toxicity from solutions that are used in association with lenses. More serious complications, such as inflammation and infection, can arise. All these changes can be detected by clinicians using slitlamp biomicroscopes and keratometers if the changes are significant enough. Since the development of computers, optical instruments have become more sophisticated and have enabled the detection of subtle changes but have also facilitated more precise measurement of these conditions along with the ability to capture images of the alterations or defects. This article describes some of the newer techniques and, specifically, the application of optical coherence tomography, confocal microscopy, and esthesiometry.

Purpose: To compare the effects of two different oxygen transmissible (Dk/t) lenses on corneal shape and optical performance after one night of corneal refractive therapy (CRT(R)) for myopia., Methods: Twenty myopic subjects were fit with Menicon Z (MZ) (Dk/t = 90.6, Paragon CRT(R) lenses) on one eye and an Equalens II (EII) CRT lens (Dk/t = 47.2) on the contralateral eye (eye randomized). Corneal topography, refractive error and aberrations were measured before lens insertion (baseline), and the following day after overnight lens wear, on lens removal and 1, 3, 6, 12 h later. Root mean square wavefront errors were measured using 4.5 mm pupils., Results: Averaged over position and time, the horizontal corneal curvature was statistically different between the MZ and EII lens-wearing eyes (p = 0.011). The central cornea flattened similarly (p = 0.886) and the mid-periphery steepened in both eyes (p = 0.061) from baseline. The EII lens-wearing eyes were steeper in the mid-periphery than the MZ eyes immediately after lens removal and at the 1-h visit (p < or = 0.032). Central corneal flattening and mid-peripheral corneal steepening regressed over time (all p < 0.001) but did not recover to baseline by 12 h (all p < 0.004). Myopia was reduced equally by 0.84 +/- 0.83 D for the MZ-lens wearing eyes and 0.84 +/- 0.87 D for the EII eyes (p = 0.969). Coma increased from baseline 1.85X (0.056 +/- 0.081 microm) for the MZ-lens wearing eyes and 1.72X (0.048 +/- 0.084 microm) for the EII eyes (both p < 0.001). Spherical aberration increased from baseline 4.55X (0.101 +/- 0.077 microm) for the MZ-lens wearing eyes and 4.31X (0.085 +/- 0.076 microm) for the EII eyes (both p < 0.001), but there were no differences between the MZ and EII eyes (all p > or = 0.308). Coma and spherical aberration did not return to baseline by 12 h (both p < or = 0.007)., Conclusions: After one night of CRT lens wear, changes in corneal shape were slightly different, with more mid-peripheral steepening in the EII eyes compared to the MZ eyes. Change in central corneal curvature and optical performance were similar in both eyes.

Purpose: To investigate the corneal shape and optical performance following one night of Corneal Refractive Therapy for hyperopia (CRTH)., Methods: Twenty subjects (spherical equivalent: -2.14 +/- 2.54 D) were fit with a Paragon CRTH lens (Dk = 100) on one eye randomly. The other eye served as the control. Aberrations, refractive error, and corneal topography at various locations along the horizontal meridian were measured at baseline prior to lens insertion, and immediately after lens removal and at 1, 3, 6, 12, and 28 hours later. Root mean square wavefront errors were measured using a 4.5 mm pupil size., Results: After one night of CRTH lens wear, the central cornea steepened and paracentral region flattened in the experimental eyes (p < 0.001), whereas no significant location effect was found in the control eyes (p = 0.139). Refractive error (mean +/- SE) changed by 1.23 +/- 0.21 D (p < 0.001). The defocus increased by 0.58 +/- 0.09 microm (p < 0.001). Higher-order aberrations, coma, and spherical aberrations increased by factors of 2.69, 2.58, and 4.07, respectively (all p < 0.001). Spherical aberrations shifted from positive to negative. Astigmatism did not change over time (p = 0.771). All parameters returned to baseline by 28 hours (all p > or = 0.808). Aberrations and refractive error did not change in the control eyes (all p > or = 0.082). CONCLUSIONS.: The CRTH lens steepens the central cornea and flattens the paracentral region, which alters the ametropia by inducing a myopic shift. It appears to be effective for correcting hyperopia and also is reversible.

There are about 35 million contact lens wearers in North America, and about half of them are symptomatic of dryness and discomfort, more commonly experienced at the end of the lens wearing day. Most of these contact lens wearers do not suffer from true dry eye, which is a pervasive and ubiquitous disease or condition that affects many millions of people in North America. It seems fairly clear that the lens causes the eye to become uncomfortable or "dry," and unless it is effectively remedied, the patient will most likely discontinue lens wear. This review describes the dryness and discomfort effects of contact lenses and how contact lens properties with novel solutions have the potential for eliminating or alleviating these symptoms.

Purpose: To assess the corneal swelling response to two myopic correction corneal refractive therapy (CRT) lenses of varying Dk/t values, worn for a single night. Change in thickness of the total cornea, stroma, and epithelium was measured across the horizontal meridian using optical coherence tomography (OCT)., Methods: In this double-masked, randomized study, twenty subjects wore a CRT design lens in each eye, manufactured from Menicon Z (MenZ; Dk/t = 91) and Equalens II (EqII; Dk/t = 47) materials. Baseline corneal thickness was measured centrally and at four points either side of the central cornea using OCT, the night before sleeping at the Centre for Contact Lens Research. The next morning, lenses were removed, and thickness measurements were repeated 1, 3, 6, and 12 h after removal., Results: On lens removal, the MenZ eye had central and paracentral corneal swelling (mean +/- SD) of 4.1 +/- 2.0% and 5.6 +/- 2.4%, and the EqII eye had 5.8 +/- 2.6% and 7.0 +/- 2.6%. These values were significantly different from baseline (ReANOVA; p < 0.001) and were different between lens materials (p < 0.001). The central epithelium thinned by 10.0 +/- 4.5% in the MenZ eye and by 10.2 +/- 8.5% in the EqII eye, with the mid-peripheral epithelium thickening by 13.4 +/- 7.9% in the MenZ eye and 18.3 +/- 9.8% in the EqII eye (all changes different from baseline p < 0.001). These epithelial values were not statistically different between materials (p > 0.05). Stromal swelling values on lens removal were 5.7 +/- 2.2% centrally and 5.5 +/- 3.0% mid-peripherally (MenZ) and 7.7 +/- 3.1% centrally and 6.6 +/- 2.9% mid-peripherally (EqII) (all p < 0.001 from baseline). Central stromal swelling was different between eyes at lens removal (p < 0.001). Stromal thickness in both eyes returned to baseline values within 3 h., Conclusion: The higher-Dk/t MenZ material caused significantly less overnight corneal and stromal swelling than the Eqll material, which reinforces the need to prescribe lenses with high Dk/t for overnight wear. Neither central epithelial thinning nor paracentral thickening are significantly affected by Dk/t.

Purpose: : The purpose of the study was to monitor the efficacy of corneal refractive therapy (CRT) lenses to reduce myopia over a 4-week period. Refractive error, keratometry, high and low contrast acuity, and subjective vision after 28 days of using CRT contact lenses were measured., Methods: : Twenty-three myopes wore CRT HDS lenses, Dk = 100. The Nikon autokefractor/keratometer was used to measure the refractive error and keratometric changes. Visual acuity was measured using computerized high and low contrast charts and the subjects completed visual analog scales characterizing their vision on a daily basis. Measurements were performed at baseline (before lens insertion before sleep), immediately after lens removal the next morning and at 1, 3, 7, and 14 hours after eye opening. Measurements were made on the days following 1, 4, 10, and 28 nights of lens wear. After 72 hours of no lens wear, these parameters were again measured to assess corneal recovery., Results: : The pretreatment manifest refraction (mean of OD and OS +/- standard deviation [SD]) was -2.72 DS +/- 1.06 and -0.55 DC +/- 0.40. Myopic spherical equivalent refractive error (+/- SD) decreased by 1.30 DS +/- 0.53 (range 0-3 D) immediately after lens removal on day 1 and by 2.59 DS +/- 0.77 by day 28 (range 1.25-3.88 D). The cylinder remained unchanged. Uncorrected visual acuity improved by 5 lines after one night and reached 0.00 LogMAR (6/6) by day 4. Visual acuity was maintained throughout the day by day 10. The day and time effect of the spherical equivalent change and the central corneal radius of curvature were statistically significant (p < 0.01) up to day 10 and remained the same until day 28. Central (autokeratometer) Ks flattened by 1.28 D +/- 1.35 after one night and 2.33 D +/- 1.30 by day 28. The subjective vision improved significantly from day 1 to day 28 (p < 0.01) and was maintained throughout the day from day 4 to day 28 (p < 0.01). All measures did not recover completely to baseline after 72 hours of no lens wear., Conclusions: : CRT lenses significantly reduced myopia, improved visual acuity and subjective vision, and flattened central corneal curvature. Maximal effect was achieved after 10 days and was maintained for the rest of the study period.

Objectives: To compare the ocular effects of low Dk hydrogel and high Dk silicone hydrogel contact lenses., Methods: A review of recent literature was conducted to determine the effects of wearing low and high Dk soft lenses on corneal swelling, vascular response, refractive error and the corneal epithelium., Results: High Dk silicone hydrogel contact lenses became available for research and clinical practice almost 10 and 5 years ago respectively. During that time many studies have been conducted and it has been demonstrated repeatedly how much improvement there has been to the physiological response of the eye particularly when wearing the lenses on an overnight basis., Conclusions: Although silicone hydrogels only constitute about 2% of current wearers, their positive effects on the eye compared with low Dk hydrogel lenses should make them the most dominant lenses in the near future.

Purpose: To investigate thickness changes of the total cornea and epithelium across the horizontal corneal meridian after 4 weeks of overnight corneal refractive therapy (CRT) rigid contact lens (Paragon Vision Sciences, Mesa, AZ) wear., Methods: Thirty subjects were fitted with CRT contact lenses (Dk/t = 67), which were worn overnight for 4 weeks. Corneal thickness was measured at nine locations along the horizontal meridian by using optical coherence tomography (OCT) before lens insertion in the evening. Corneal thickness was measured the next morning immediately after lens removal and 1, 3, 7, and 14 hours later. This was repeated on days 4, 10, and 28 of the study and then 3 days after discontinuing lens wear., Results: Twenty-three subjects completed the study. At lens removal on day 1, the central and paracentral cornea swelled by 4.9% and 6.2%, respectively (both P = 0.000). The central epithelium thinned by 7.3%, and the mid peripheral epithelium thickened by 13% (both P = 0.000). Corneal swelling recovered throughout the day, with most of the deswelling taking place within the first 3 hours after lens removal. Maximal central epithelial thinning reached 13.5% by day 4. Three days after the study completion, corneal and epithelial thickness had recovered to baseline values., Conclusions: This study shows that CRT lenses induce differential overnight swelling across the cornea, with rapid deswelling during the day. Central epithelial thinning and paracentral thickening occurs, with recovery 3 days after discontinuation of lens wear.

Purpose: 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=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 +/- 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 degrees across 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., Results: After one night of lens wear, myopia decreased in the test eye by 1.18 +/- 0.81 D, which was significantly different from baseline (P<0.001). No significant change was found in the control eye. Twelve hours after removal, two thirds of the myopic reduction was still present. Different topographical swelling patterns were induced by the two lens designs, with greatest swelling occurring in the center with the control lens and in the midperiphery with the test lenses (polynomial regression: P<0.005). Significantly greater central corneal swelling was found with the control lens than the test lens (6.9% +/- 3.1% vs. 4.9% +/- 2.0%, respectively, P=0.006). The effect on epithelial thickness differed between lenses and depended on both position and time (F(48,912)=2.3; P=0.000). Immediately after removal of the test lens, the central epithelium was 5.1% +/- 4.5% thinner than baseline, and all other locations (P<0.005 post hoc tests) and the epithelium in the midperiphery showed significant thickening (1.9% on the temporal side and 2.4% on the nasal side, both P<0.006 compared with the baseline). There were no significant changes in epithelial thickness with the control lens during the study period (post hoc tests: P>0.05)., Conclusions: The optical coherence tomograph is a sensitive instrument that can detect small changes in epithelial and corneal thickness across the entire cornea. Topographical thickness changes of the epithelium and total cornea induced by one night of reverse-geometry lens wear appear to be associated with the decrease of myopia.

Purpose: To determine changes in topographical thickness of the epithelium and total cornea after hydrogel (2-hydroxyethyl methacrylate; HEMA or soft lens) and PMMA rigid contact lens wear with eyes closed, as measured by optical coherence tomography (OCT)., Methods: Epithelial and total corneal thickness in 18 neophyte eyes was measured with OCT at intervals of 10 degrees across a 10-mm zone of the horizontal meridian of the cornea, before and after 3 hours of soft and rigid contact lens wear with the eye closed. These measurements were repeated 20 minutes after removal of the lenses., Results: Lens type, time, and location were found to be significant main influences (P < 0.0001) on corneal swelling in patched eyes, by three-way ANOVA, and there was a significant three-way interaction among lens type, time, and location (F((16,272)) = 1.78, P = 0.033). However, there was no significant main effect and interaction of epithelial thickness (F((16, 272)) = 0.33, P = 0.99). Immediately after removal of the lenses, total corneal thickness in the horizontal meridian was significantly greater with both soft and PMMA lenses (P < 0.001) at each location with each lens, compared with the baseline measurements. With both lenses, the increase in actual thickness and percentage of corneal swelling at the center was greater than at each peripheral point (excluding the first 10 degrees points; P < 0.005). HEMA lenses caused greater corneal swelling than the PMMA lenses at each location immediately after removal of the lenses (P < 0.005)., Conclusions: This study shows that corneal swelling is dependent on lens type and corneal location when eyes are closed, but epithelial thickness across the horizontal corneal meridian does not change during lens wear with eyes closed. OCT is an efficient method of measuring topographical corneal and epithelial thickness in response to contact lens wear.

Purpose: To assess the tear film, ocular surfaces, and symptoms of ocular discomfort in a presbyopic population before and after contact lens wear., Methods: A total of 150 presbyopes (49% were previous soft contact lens wearers) participated in a clinical trial in which they wore either monovision (single vision Acuvue lenses) or Acuvue Bifocal contact lenses. Clinical measurements of tear film, biomicroscopy, and corneal sensitivity as well as subjective ratings using the Dry Eye Questionnaire were collected at the initial visit and repeated after 6 months. Comparisons were made between age groups (40 to 51 years and 52 to 71 years) and genders before and after contact lens wear. Associations between objective and subjective tests were sought., Results: After 6 months of contact lens wear, clinical signs had worsened by less than one-half of a grade, and tear break up time (TBUT) worsened by 3 s. Only TBUT was lower for the older age group. Females had less bulbar hyperemia, more sensitive eyes, more lissamine green staining, and lower TBUT and phenol red thread measurements (all p < 0.04). Twenty-eight percent experienced dryness before contact lens wear, but this figure increased to 68% when wearing contact lenses. There were no age differences, but almost twice as many females as males reported dryness. Reporting symptoms of dryness was associated with gender, corneal sensitivity, and type of corneal staining., Conclusions: These results provide a representation of the ocular surface condition and symptoms of ocular discomfort in the middle-aged population and seem similar to reports of younger populations. Wearing contact lenses seems to influence dry eye symptoms more than age or gender. Therefore, presbyopes should not be excluded from consideration for contact lens fitting.

Previous studies have shown that contact lens wear may affect palpebral aperture size (PAS). In this study, 74 wearers of rigid lenses were matched for sex and age with soft lens wearers and nonwearers. Partial face photographs were taken of all subjects, in the case of contact lens wearers, after lens removal. PAS was determined by measuring the resulting 35-mm transparencies on a Mitutoya profile projector. The mean PAS of the rigid lens wearers (9.76 +/- 0.99 mm) was found to be significantly smaller than that of the soft lens wearers (10.24 +/- 0.94 mm) and the nonwearers (10.10 +/- 1.11 mm) (p = 0.0154, analysis of variance). There was no significant difference between the PAS of soft lens wearers and nonwearers. This study supports the hypothesis that rigid lens wear causes a decrease in PAS.

Patient preferences and ocular responses were compared between rigid and soft contact lenses by randomly fitting 32 neophyte subjects with a rigid lens in 1 eye and a soft lens in the contralateral eye. Twenty-seven of 32 subjects completed the 3-month study and 16 subjects were willing to continue for an additional 3-month extension. Subjects preferred the comfort and handling of the soft lens but preferred the vision provided by the rigid lens and initially its ease of maintenance. There was also a marked preference for the soft lens when all aspects of lens wear were compared. Objectively, the rigid lenses were responsible for more ocular changes than the soft lenses. Palpebral aperture sizes of the rigid gas permeable (RGP) wearing eyes decreased significantly (0.5 mm; p < 0.05) compared to the soft lens wearing eyes. The incidence of corneal staining was significantly greater in the rigid lens wearing eye (50% RGP vs. 22% soft) but limbal injection was greater in the soft lens wearing eye (18% soft vs. 6% RGP). Refractive sphere, cylinder, and corneal astigmatism decreased in the rigid lens wearing eye after 3 months. This daily wear clinical trial has shown a marked subjective preference for wearing soft lenses with fewer short-term ocular effects.

The flexure of spherical rigid lenses (various materials) and a soft lens was measured using automated over-keratometry on 6 adapted rigid lens wearers (12 eyes) whose corneal toricity ranged from 1.37 to 3.87 D. The results showed: (1) that there was no significant difference in flexure between polymethyl methacrylate (PMMA), silicone acrylate, and the fluorosilicone acrylate lenses (whose Dks ranged from 0 to 115). However, Advent (fluoropolymer) did flex significantly more than the other rigid lenses, and significantly less than the soft lens (Bausch & Lomb U4) and (2) that lens flexure of the rigid lenses did not alter over a 2-h period. We also measured high and low contrast visual acuity (HCVA and LCVA), and the results from subjects wearing Advent and the soft lens were significantly worse than with the other rigid lenses. Finally, the results of this study showed no correlation between rigid lens flexure and permeability and between rigid lens flexure and visual acuity when Advent was excluded from the linear regression analysis.

Superficial corneal epithelial striations described as fibrillary lines have been documented as a common finding in normal and keratoconic eyes. We first noticed these fine white structures in both soft and rigid contact lens wearers. This prompted us to investigate whether the prevalence of these lines was greater in contact lens wearers than in non-lens wearers. Our results indicated that although the lines were more frequently observed in lens wearers (35.7% of 42 patients) than in the controls (19.0% of 42 patients), the difference was not statistically significant (p = 0.0867, chi 2 analysis). We speculate that lens wear makes fibrillary lines more visible but is not responsible for their presence.

A short-term study of the physiologic response of the cornea to polymethyl methacrylate (PMMA) contact lenses and hard, gas-permeable contact lenses of different materials (polycon and Menicon 02), thicknesses, and fittings, was carried out on nine unadapted subjects using one eye as the experimental eye and the other as the control eye (no lens). Changes in corneal thickness were monitored at seven locations across the cornea using an electronic micropachymeter. It was found that gas-permeable lenses produced less corneal swelling than the PMMA lenses. However, lens thickness and the fit of the lens were still important control variables with these gas-permeable lenses. The thin gas-permeable lens produced less swelling than thicker lenses, and the flatter fitting gas-permeable lenses produced less swelling than the steeper fitting lenses. The swelling with all the hard lenses studied was confined primarily to the central 6 mm of the cornea.