Silicone hydrogel versus hydrogel soft contact lenses for differences in patient-reported eye comfort and safety: A Cochrane systematic review summary.

SIGNIFICANCE: This work is significant because it is the first Cochrane systemic review that compares the comfort and safety of hydrogel and silicone hydrogel soft contact lenses (SCL). PURPOSE: This study aimed to conduct a systemic review of randomized trials comparing the comfort and safety of silicone hydrogel and hydrogel SCLs. METHODS: CENTRAL, MEDLINE Ovid, EMBASE.com, PubMed, LILACS, ClinicalTrials.gov, and World Health Organization International Clinical Trials Registry Platform were searched on or before June 24, 2022, to identify randomized clinical trials that compared silicone hydrogel and hydrogel SCLs. RESULTS: Seven trials were identified and evaluated. One trial reported Ocular Surface Disease Index results, with the evidence being very uncertain about the effects of SCL material on Ocular Surface Disease Index scores (mean difference, -1.20; 95% confidence interval, -10.49 to 8.09). Three trials reported visual analog scale comfort score results, with no clear difference in comfort between materials, although results were of low certainty; trial results could not be combined because the three trials reported results at different time points. None of the included trials reported Contact Lens Dry Eye Questionnaire 8 or Standard Patient Evaluation of Eye Dryness scores. There was no evidence of a clinically meaningful difference (>0.5 unit) between daily disposable silicone hydrogel and hydrogel SCLs in corneal staining, conjunctival staining, or conjunctival redness (very low certainty evidence). CONCLUSIONS: The overall evidence for a difference between all included silicone hydrogel and hydrogel SCL trials was of very low certainty, with most trials judged as having a high overall risk of bias. There was insufficient evidence to support recommending one SCL material over the other. Future well-designed trials are needed to generate high certainty evidence to further clarify differences in SCL material comfort and safety.

Silicone hydrogel versus hydrogel soft contact lenses for differences in patient-reported eye comfort and safety.

BACKGROUND: Ocular discomfort is the leading cause of permanent discontinuation of soft contact lens (SCL) wear. Silicone hydrogel and hydrogel materials are the two major categories of SCLs, with silicone hydrogel materials being newer and more breathable than hydrogel materials. Whether comfort is associated with SCL material is controversial despite numerous studies. Similarly, the difference between these materials in terms of safety outcomes (e.g. frequency of microbial keratitis) is unclear. OBJECTIVES: To evaluate the comparative effectiveness and safety of silicone hydrogel compared with hydrogel SCLs on self-reported comfort, dry eye test results, and adverse events in SCL-wearing adults 18 years of age or older. SEARCH METHODS: The Cochrane Eyes and Vision Information Specialist searched the electronic databases for randomized controlled trials (RCTs). There were no restrictions on language or date of publication. We searched the Cochrane Central Register of Controlled Trials (CENTRAL, including the Cochrane Eyes and Vision Trials Register; 2022, Issue 6), MEDLINE Ovid, Embase.com, PubMed, LILACS (Latin American and Caribbean Health Science Information database), ClinicalTrials.gov, and World Health Organization (WHO) International Clinical Trials Registry Platform (ICTRP). We also searched the reference lists of identified studies, review articles, and guidelines for information about relevant studies that may not have been identified by our search strategy. Furthermore, we contacted investigators regarding ongoing trials. The most recent database search was conducted on 24 June 2022. SELECTION CRITERIA: Our search selection criteria included RCTs, quasi-RCTs, and cross-over RCTs. DATA COLLECTION AND ANALYSIS: We applied standard Cochrane methodology. MAIN RESULTS: We included seven parallel-group RCTs conducted in the USA, the UK, Australia, Germany, India, and Turkey. A total of 1371 participants were randomized. The duration of SCL wear ranged from one to 52 weeks. Study characteristics and risk of bias The median number of participants per trial was 120 (interquartile range: 51 to 314), and the average age ranged from 20.7 to 33.0 years. Women represented the majority of participants (range 55% to 74.9%; 5 RCTs). Collectively, the included trials compared eight different silicone hydrogel SCLs with three different hydrogel SCLs. Five trials compared daily disposable SCLs, and two compared extended wear SCLs (worn for seven days and six nights). New SCL wearers were enrolled in three trials. Two trials included both new and established SCL wearers, and two trials did not report participants' history of SCL use. Five trials were sponsored by industry. We judged the overall risk of bias to be 'high' or 'some concerns' for the safety and efficacy outcomes. Findings One trial reported Ocular Surface Disease Index (OSDI) results, with the evidence being very uncertain about the effects of SCL material on OSDI scores (mean difference -1.20, 95% confidence interval [CI] -10.49 to 8.09; 1 RCT, 47 participants; very low certainty evidence). Three trials reported visual analog scale comfort score results, with no clear difference in comfort between materials, but the evidence was of very low certainty; trial results could not be combined because the three trials reported results at different time points. The evidence is very uncertain about the effect of SCL material on discontinuation of contact lens wear (risk ratio [RR] 0.64, 95% CI 0.11 to 3.74; 1 RCT, 248 participants). None of the included trials reported Contact Lens Dry Eye Questionnaire (CLDEQ-8) or Standard Patient Evaluation of Eye Dryness (SPEED) scores. There was no evidence of a clinically meaningful difference (> 0.5 unit) between daily disposable silicone hydrogel and hydrogel SCLs in corneal staining, conjunctival staining, or conjunctival redness (very low certainty evidence). Adverse events Very low certainty evidence from two trials comparing daily disposable SCLs suggested no evidence of a difference between lens materials in the risk of vision-threatening adverse events at one to four weeks (RR 0.68, 95% CI 0.08 to 5.51; 2 RCTs, 368 participants). Two trials comparing extended wear SCLs indicated that hydrogel SCLs may have a 2.03 times lower risk of adverse events at 52 weeks compared with silicone hydrogel SCLs (RR 2.03, 95% CI 1.38 to 2.99; 815 participants), but the certainty of evidence was very low. AUTHORS' CONCLUSIONS: The overall evidence for a difference between all included silicone hydrogel and hydrogel SCLs was of very low certainty, with most trials at high overall risk of bias. The majority of studies did not assess comfort using a validated instrument. There was insufficient evidence to support recommending one SCL material over the other. For extended wear, hydrogel SCL may have a lower risk of adverse events at 52 weeks compared to silicon hydrogel. Future well-designed trials are needed to generate high certainty evidence to further clarify differences in SCL material comfort and safety.

Seasonal Effect on Ocular Sun Exposure and Conjunctival UV Autofluorescence.

PURPOSE: To evaluate feasibility and repeatability of measures for ocular sun exposure and conjunctival ultraviolet autofluorescence (UVAF), and to test for relationships between the outcomes. METHODS: Fifty volunteers were seen for two visits 14 ± 2 days apart. Ocular sun exposure was estimated over a 2-week time period using questionnaires that quantified time outdoors and ocular protection habits. Conjunctival UVAF was imaged using a Nikon D7000 camera system equipped with appropriate flash and filter system; image analysis was done using ImageJ software. Repeatability estimates were made using Bland-Altman plots with mean differences and 95% limits of agreement calculated. Non-normally distributed data was transformed by either log10 or square root methods. Linear regression was conducted to evaluate relationships between measures. RESULTS: Mean (±SD) values for ocular sun exposure and conjunctival UVAF were 8.86 (±11.97) hours and 9.15 (±9.47) mm, respectively. Repeatability was found to be acceptable for both ocular sun exposure and conjunctival UVAF. Univariate linear regression showed outdoor occupation to be a predictor of higher ocular sun exposure; outdoor occupation and winter season of collection both predicted higher total UVAF. Furthermore, increased portion of day spent outdoors while working was associated with increased total conjunctival UVAF. CONCLUSIONS: We demonstrate feasibility and repeatability of estimating ocular sun exposure using a previously unreported method and for conjunctival UVAF in a group of subjects residing in Ohio. Seasonal temperature variation may have influenced time outdoors and ultimately calculation of ocular sun exposure. As winter season of collection and outdoor occupation both predicted higher total UVAF, our data suggests that ocular sun exposure is associated with conjunctival UVAF and, possibly, that UVAF remains for at least several months after sun exposure.

Examination of human meibum collection and extraction techniques.

PURPOSE: To compare various meibum collection methods and extraction techniques. METHODS: Sixty subjects, all successful contact lens wearers, were seen on two visits. Meibum was collected from the lower lid of the right eye with a glass microcapillary tube, and with a Dacron swab, cytology microbrush, or spatula from the left eye. Extraction with 2:1 chloroform:methanol was done either immediately or after data collection was complete. Individual samples were divided into four equal aliquots for analysis of total lipids, cholesterol, and inorganic phosphates by assay-based techniques. Effects of collection method, extraction, and dry eye status were examined using repeated measures analysis of variance and logistic regression. RESULTS: Total lipids showed significance for collection device (p < 0.0001) but not for extraction technique (p = 0.13) or dry eye status (p = 0.97). Dacron swab collection was associated with more total lipid on average than each other collection device (p < 0.0001). The cholesterol assay showed significance of collection device (p < 0.0001) and extraction technique (p = 0.0002) but not dry eye status (p = 0.55). Spatula collection was associated with more cholesterol on average than each other collection device (p < 0.0001). For inorganic phosphates, immediate extraction (p < 0.0001), cytology microbrush collection (p < 0.0001), and non-dry eye status (p = 0.03) were associated with the greater likelihood of detection. CONCLUSIONS: Dacron swab collection was associated with the highest average amount of total lipid detected, whereas spatula collection and immediate extraction was associated with the highest average amount of cholesterol detected. Cytology microbrush collection with immediate extraction on non-dry eye subjects was associated with the highest probability of detection of inorganic phosphates.

Effect of UV-absorbing Contact Lenses on Conjunctival Ultraviolet Autofluorescence.

PURPOSE: The intended purpose of UV-absorbing contact lenses is to protect the cornea and posterior ocular structures from UV-induced damage. Few studies report conjunctival effects of UV-absorbing contact lens materials. The purpose of this study was to evaluate conjunctival ultraviolet autofluorescence (UVAF) for contact lens wearers of UV-absorbing and minimally UV-absorbing materials. METHODS: Forty-four volunteers enrolled in the cross-sectional study. Three groups were recruited; non-contact lens wearers (n = 15), minimally UV-absorbing contact lens wearers (n = 15), and UV-absorbing contact lens wearers (n = 14). Ocular sun exposure was calculated using self-reported measures. Conjunctival UVAF images of temporal and nasal conjunctiva, acquired using a Nikon D7000 camera system adapted with appropriate flash and filter system, were analyzed using ImageJ. A sub-group of participants including only subjects with measurable UVAF was analyzed. RESULTS: No significant differences were present between groups found similar for age, gender, and ocular sun exposure. The area of UVAF significantly increased following lens removal for UV-absorbing contact lens wearers compared with non-contact lens wearers. Furthermore, for contact lens wearers compared with non-lens wearers, area of UVAF was significantly greater between right and left eyes (p = .04 minimally UV-absorbing, p = .01 UV-absorbing), and between nasal (p = .046 minimally UV-absorbing, p = .01 UV-absorbing), and temporal (p = .01 UV-absorbing) areas. However, no significant difference was found between contact lens wearers of the two groups. No difference was found between nasal and temporal UVAF regions during contact lens wear (p = .28) or after lens removal (p = .16) (Mann-Whitney U). CONCLUSIONS: Contact lens materials have conjunctival effects, with increased UVAF in both UV-absorbing and minimally UV-absorbing contact lens wearers compared with non-lens wearers. UV-absorbing and minimally UV-absorbing contact lens materials appear to influence nasal and temporal areas of the ocular surface equally.

Oxidative Stress Measures of Lipid and DNA Damage in Human Tears.

Purpose: We evaluate feasibility and repeatability of measures for lipid peroxidation and DNA oxidation in human tears, as well as relationships between outcome variables, and compared our findings to previously reported methods of evaluation for ocular sun exposure. Methods: A total of 50 volunteers were seen for 2 visits 14 ± 2 days apart. Tear samples were collected from the inferior tear meniscus using a glass microcapillary tube. Oxidative stress biomarkers were quantified using enzyme-linked immunosorbent assay (ELISA): lipid peroxidation by measurement of hexanoyl-lysine (HEL) expression; DNA oxidation by measurement of 8-oxo-2'-deoxyguinosone (8OHdG) expression. Descriptive statistics were generated. Repeatability estimates were made using Bland-Altman plots with mean differences and 95% limits of agreement were calculated. Linear regression was conducted to evaluate relationships between measures. Results: Mean (±SD) values for tear HEL and 8OHdG expression were 17368.02 (±9878.42) nmol/L and 66.13 (±19.99) ng/mL, respectively. Repeatability was found to be acceptable for both HEL and 8OHdG expression. Univariate linear regression supported tear 8OHdG expression and spring season of collection to be predictors of higher tear HEL expression; tear HEL expression was confirmed as a predictor of higher tear 8OHdG expression. Conclusions: We demonstrate feasibility and repeatability of estimating previously unreported tear 8OHdG expression. Seasonal temperature variation and other factors may influence tear lipid peroxidation. Support is demonstrated to suggest lipid damage and DNA damage occur concurrently on the human ocular surface.

The presence and significance of polar meibum and tear lipids.

The ocular tear film is a complex structure composed of a number of elements. While all of these components serve valuable functional and structural roles, the external lipid layer has been a focus because it is known to play a critical role in dry eye. Traditionally, meibomian gland phospholipids have been considered to be the vital amphiphilic molecules needed to create an interphase between the outer nonpolar lipid layer and inner aqueous layers, yet recent work has called this theory into question. The purpose of this review is to clarify the current understanding of the origins, identity, and significance of polar tear lipids. Studies indicate that both phospholipids and ω-hydroxy fatty acids likely play a critical role in tear film stability. Studies also indicate that polar lipids likely originate from multiple sources and that they are integrally involved in ocular surface disease. Additional studies are needed to fully understand the origins and significance of polar tear lipids, because to date only correlational evidence has described their hypothesized origins and functions.