Intraocular Scattering, Blinking Rate, and Tear Film Osmolarity After Exposure to Environmental Stress

Ocular effects of exposure to low-humidity environment with contact lens wear: A pilot study

PURPOSE

To compare the ocular effects of exposure to a low-humidity environment with and without contact lens (CL) wear using various non-invasive tests.

METHODS

Fourteen habitual soft CL wearers were exposed to controlled low humidity (5% relative humidity [RH]) in an environmental chamber for 90 min on two separate occasions. First, when wearing their habitual spectacles and then, on a separate visit, when wearing silicone hydrogel CLs that were fitted specifically for this purpose. All participants had adapted to the new CL prior to data collection. Three non-invasive objective measurements were taken at each visit: blinking rate, objective ocular scatter (measured using the objective scatter index) and ocular surface cooling rate (measured using a long-wave infrared thermal camera). At each visit, measurements were taken before the exposure in comfortable environmental conditions (RH: 45%), and after exposure to environmental stress (low humidity, RH: 5%).

RESULTS

CL wearers showed increased blinking rate (p < 0.005) and ocular scatter (p = 0.03) but similar cooling rate of the ocular surface (p = 0.08) when compared with spectacle wear in comfortable environmental conditions. The exposure to low humidity increased the blinking rate significantly with both types of corrections (p = 0.01). Interestingly, ocular scatter (p = 0.96) and cooling rate (p = 0.73) were not significantly different before and after exposure to low humidity. There were no significant two-way interactions between correction and exposure in any of the measurements.

CONCLUSIONS

CLs significantly increased the blinking rate, which prevented a quick degradation of the tear film integrity as it was refreshed more regularly. It is hypothesised that the increased blinking rate in CL wearers aids in maintaining ocular scatter quality and cooling rate when exposed to a low-humidity environment. These results highlight the importance of blinking in maintaining tear film stability.

Tear Film Stability Affects Visual Acuity After Implantations of Monofocal and Multifocal Intraocular Lenses: An Evaluation by Objective Scatter Index

Purpose

To assess the impact of tear film on postoperative visual acuity after cataract surgery to implant an intraocular lens (IOL).

Methods

Tear break-up time (TBUT), Schirmer I test, objective scatter index (OSI), and uncorrected distance visual acuity (UCDVA), intermediate visual acuity (UCIVA), and near visual acuity (UCNVA) were collected 6 months after cataract surgery.

Results

Fifteen eyes with monofocal (Mo-) IOLs and 15 eyes with multifocal (Mu-) IOLs from 30 subjects were included. The Mu-IOL group exhibited higher baseline OSI (1.92 ± 0.69, P < 0.001). Negative correlations-both groups: tear film-related OSI (TF-OSI) and TBUT/Schirmer I test; Mo-IOL: TBUT and logMAR UCDVA-and positive correlations-both groups: TF-OSI and baseline OSI, baseline OSI/TF-OSI and logMAR UCDVA; Mu-IOL: baseline OSI/TF-OSI and logMAR UCIVA/UCNVA-were found. Linear regression showed associations between TF-OSI and TBUT (Mo-IOL: R2 = 0.455, P = 0.006; Mu-IOL: R2 = 0.454, P = 0.006)/Schirmer I test (Mo-IOL: R2 = 0.527, P = 0.002; Mu-IOL: R2 = 0.266, P = 0.049). Multiple regression showed associations between baseline OSI (Mo-IOL: R2 = 0.309, P = 0.032; Mu-IOL: R2 = 0.305, P = 0.033)/TF-OSI (Mo-IOL: R2 = 0.332, P = 0.025; Mu-IOL: R2 = 0.523, P = 0.002)/TBUT (Mo-IOL only: R2 = 0.315, P = 0.029) and logMAR UCDVA.

Conclusions

TF-OSI reflects the UCDVA performance in eyes with IOLs and facilitates a better understanding of the effects of the tear film.

Translational Relevance

TF-OSI offers a developmental and objective approach to assessing the changing visual performance caused by tear film after cataract surgery and IOL implantation in clinical practices.

Recent Advances in Hydrogels for the Diagnosis and Treatment of Dry Eye Disease

Dry eye disease (DED) is the most common clinical ocular surface disease. Given its multifactorial etiology, no consensus has been reached on the diagnosis criteria for dry eye disease. Topical drug administration remains the mainstay of treatment but is limited to the rapid clearance from the eye surface. To address these problems, hydrogel-based materials were designed to detect biomarkers or act as drug delivery systems by taking advantage of their good biocompatibility, excellent physical and mechanical properties, and long-term implant stability. Biosensors prepared using biocompatible hydrogels can be sensitive in diagnosing DED, and the designed hydrogels can also improve the drug bioavailability and retention time for more effective and long-term treatment. This review summarizes recent advances in the use of hydrogels for diagnosing and treating dry eye, aiming to provide a novel reference for the eventual clinical translation of hydrogels in the context of dry eye disease.

Comparative analysis of a presbyopia-correcting intraocular lens that combines extended depth-of-focus and bifocal profiles with a standard monofocal intraocular lens

Background

Recently, a new presbyopia-correcting intraocular lens (IOL) that combines extended depth-of-focus and bifocal profiles (ZFR00: Tecnis® Synergy®, Johnson & Johnson Vision, Santa Ana, CA, USA) has been established and several studies have been reported. We attempted to compare the performance with a standard IOL (ZCB00: Tecnis® monofocal, Johnson & Johnson Vision, Santa Ana, CA, USA) manufactured using the same material from the same company, which has been extensively used worldwide.

Methods

The medical records of patients undergoing cataract surgery with ZCB00 or ZFR00 implantation between March 2021 and September 2021 and with available 3-month visit data were reviewed. Uncorrected near, intermediate, and distance visual acuity (VA), corrected distance VA, and optical quality were the main outcome measures.

Results

This study included forty-six patients (64 eyes), with twenty-one patients (32 eyes) implanted with ZCB00 and twenty-five patients (32 eyes) implanted with ZFR00. The average age of the patients was 66.0 ± 10.1 (range: 40 to 82) and 65.1 ± 4.7 (range: 59 to 77) years in the ZCB00 and ZFR00 groups, respectively. The preoperative characteristics did not differ significantly between the two groups. Compared to the ZCB00 group, the ZFR00 group demonstrated significantly superior intermediate and near VA (p < 0.001) at 3 months postoperatively. The ZFR00 group showed significantly lower objective measured optical quality than that in the ZCB00 group.

Conclusions

The ZFR00 exhibited a continuous range of vision and a smooth defocus curve, while the ZCB00 provided superior objective optical quality.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12886-022-02516-6.

Associations of Humidity and Temperature With Cataracts Among Older Adults in China

Background

The burden of cataracts was substantial in the current aging world. However, few epidemiological studies have examined the associations between climate and weather conditions and cataract in older populations. We aimed to investigate the associations of air relative humidity and temperature with cataracts in older adults in China.

Methods

We used the cohort data from 2002, 2005, 2008, 2011, 2014, and 2018 waves of the Chinese Longitudinal Healthy Longevity Survey (CLHLS). A total of 62,595 Chinese older adults aged between 65 and 105 years were included in the analyses. City-level annual average air humidity and temperature during 2001 and 2017 (before the survey year) was used to measure population exposure. A cataract was self-reports based on the medical record or the doctor's diagnosis and 8,071 older adults had cataract. Covariates included socio-demographic, health status, lifestyles, and chronic conditions. We adopted the Generalized estimation equation (GEE) model to analyze the associations of relative humidity and temperature with cataracts.

Results

We found that the average relative humidity (OR: 0.99; 95% CI: 0.98–0.99) in the past year was inversely associated with cataract likelihoods in older adults and a positive association between temperature (OR: 1.04; 95%CI: 1.03,1.05) in the past year and cataract likelihoods in older adults. The associations were robust in stratified analyses by sex, urban/rural residence, and education level. Furthermore, we found a nonlinear J-shaped relationship between temperature and cataract prevalence.

Conclusion

Our findings provide the evidence that higher temperature and low relative humidity may be associated with cataracts in older adults.