Current Insights on the Photoprotective Mechanism of the Macular Carotenoids, Lutein and Zeaxanthin: Safety, Efficacy and Bio-Delivery

Ocular health has emerged as one of the major issues of global health concern with a decline in quality of life in an aging population, in particular and rise in the number of associated morbidities and mortalities. One of the chief reasons for vision impairment is oxidative damage inflicted to photoreceptors in rods and cone cells by blue light as well as UV radiation. The scenario has been aggravated by unprecedented rise in screen-time during the COVID and post-COVID era. Lutein and Zeaxanthin are oxygenated carotenoids with proven roles in augmentation of ocular health largely by virtue of their antioxidant properties and protective effects against photobleaching of retinal pigments, age-linked macular degeneration, cataract, and retinitis pigmentosa. These molecules are characterized by their characteristic yellow-orange colored pigmentation and are found in significant amounts in vegetables such as corn, spinach, broccoli, carrots as well as fish and eggs. Unique structural signatures including tetraterpenoid skeleton with extensive conjugation and the presence of hydroxyl groups at the end rings have made these molecules evolutionarily adapted to localize in the membrane of the photoreceptor cells and prevent their free radical induced peroxidation. Apart from the benefits imparted to ocular health, lutein and zeaxanthin are also known to improve cognitive function, cardiovascular physiology, and arrest the development of malignancy. Although abundant in many natural sources, bioavailability of these compounds is low owing to their long aliphatic backbones. Under the circumstances, there has been a concerted effort to develop vegetable oil-based carriers such as lipid nano-emulsions for therapeutic administration of carotenoids. This review presents a comprehensive update of the therapeutic potential of the carotenoids along with the challenges in achieving an optimized delivery tool for maximizing their effectiveness inside the body.

Secondhand smoke exposure and ocular health: A systematic review

The toxicology of secondhand smoke (SHS), along with the harm of its exposure to human health, has been generally acknowledged; however, specific evidence is lacking on the association between SHS exposure and ocular health. In this systematic review (PROSPERO registration number: CRD42022247992), we included 55 original articles published by 12 May 2023, which dealt with SHS exposure and ocular disorders, such as eye irritation, conjunctivitis, dry eye diseases, uveitis, myopia, astigmatism, contact lens discomfort, age-related macular degeneration, glaucoma, and thyroid eye disease that addressed the ocular neurovascular structures of the macular, retinal nerve fiber layer, choroid, and corneal biomechanical parameters. We found compelling correlational evidence for eye irritation, conjunctivitis, and dry eye symptoms-supporting that SHS exposure was positively associated with inflammatory and allergic changes in the eyes. Yet, evidence about the associations between SHS exposure and other ocular disorders, structures, and parameters is still limited or controversial. Given the limitations of existing literature, more investigations with high quality and rigorous design are warranted to elucidate the potentially harmful effects of SHS exposure on ocular health.

TFOS Lifestyle: Impact of contact lenses on the ocular surface

Several lifestyle choices made by contact lens wearers can have adverse consequences on ocular health. These include being non-adherent to contact lens care, sleeping in lenses, ill-advised purchasing options, not seeing an eyecare professional for regular aftercare visits, wearing lenses when feeling unwell, wearing lenses too soon after various forms of ophthalmic surgery, and wearing lenses when engaged in risky behaviors (e.g., when using tobacco, alcohol or recreational drugs). Those with a pre-existing compromised ocular surface may find that contact lens wear exacerbates ocular disease morbidity. Conversely, contact lenses may have various therapeutic benefits. The coronavirus disease-2019 (COVID-19) pandemic impinged upon the lifestyle of contact lens wearers, introducing challenges such as mask-associated dry eye, contact lens discomfort with increased use of digital devices, inadvertent exposure to hand sanitizers, and reduced use of lenses. Wearing contact lenses in challenging environments, such as in the presence of dust and noxious chemicals, or where there is the possibility of ocular trauma (e.g., sport or working with tools) can be problematic, although in some instances lenses can be protective. Contact lenses can be worn for sport, theatre, at high altitude, driving at night, in the military and in space, and special considerations are required when prescribing in such situations to ensure successful outcomes. A systematic review and meta-analysis, incorporated within the review, identified that the influence of lifestyle factors on soft contact lens dropout remains poorly understood, and is an area in need of further research. Overall, this report investigated lifestyle-related choices made by clinicians and contact lens wearers and discovered that when appropriate lifestyle choices are made, contact lens wear can enhance the quality of life of wearers.

Multifunctional glycoprotein coatings improve the surface properties of highly oxygen permeable contact lenses

To achieve and maintain good operability of medical devices while reducing putative side effects for the patient, a promising strategy is to tailor the surface properties of such devices as they critically dictate the tissue compatibility and the biofouling behavior. Indeed, those properties can be strongly improved by generating mucin coatings on such medical devices. However, using coatings on optical systems, e.g., contact lenses, comes with various challenges: here, the geometrical and optical characteristics of the lens may not be compromised by either the coating process or the coating itself. In this study, we show how mucin macromolecules can be attached onto the surfaces of rigid, gas permeable contact lenses while maintaining all critical lens parameters. We demonstrate that the generated coatings improve the surface wettability (contact angles are reduced from 105° to 40° and liquid film break-up times are increased from <1 s to 31 s) and prevent tribological damage to corneal tissue. Additionally, such coatings are highly transparent (transmission values above 98 % compared to an uncoated sample are reached) and efficiently reduce lipid deposition to the lens surface by 90 % but fully maintain the geometrical and mechanical properties of the lenses. Thus, such mucin coatings could also be highly beneficial for other optical systems that are used in direct contact with tissues or body fluids.

Effect of wearing different types of face masks during dynamic and isometric resistance training on intraocular pressure

CLINICAL RELEVANCE

The use of face masks has demonstrated to be an effective strategy to prevent transmission of severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2). Wearing face masks, mainly Filtering Face Piece 2 (FFP2) masks, during exercise practice has demonstrated to affect several physiological measures.

BACKGROUND

This study was aimed at assessing the intraocular pressure (IOP) behaviour during the execution of the dynamic and isometric biceps-curl exercise with a surgical and FFP2 face mask.

METHODS

Twenty two physically active young adults performed sets of 10 repetitions against the 10-RM (repetition maximum) load and 1-minute isometric effort against a load 15% lower than the 10-RM load with the FFP2 and surgical mask and without any mask. A total of six exercise sets (3 experimental conditions [FFP2, surgical and control] × 2 exercise modalities) were performed. A rebound tonometer was used to measure IOP before, during (10 measurements), and after (30-seconds of passive recovery) each training set.

RESULTS

At rest, there were not statistically significant IOP differences (p = 0.222). During dynamic exercise, there was a progressive IOP rise (p < 0.001), and a higher IOP response with the FFP2 than without the mask (corrected p-value = 0.003). For the isometric exercise, there was a greater IOP response as a function of accumulated effort (p < 0.001), which was dependent of the face mask used (FFP2> surgical>control; corrected p-values< 0.01).

CONCLUSIONS

The FFP2 masks cause a heightened IOP response during the execution of dynamic and isometric biceps-curl exercise, suggesting that, when possible, glaucoma patients should limit the use of FFP2 masks during resistance training.

The impact of vaping on ocular health: a literature review

PURPOSE

Vaping, or the use of electronic cigarettes, was initially introduced as a step toward smoking cessation, but has become an increasingly popular option for smokers. Though advertised as safer than conventional cigarettes, these devices have been found to contain carcinogenic chemicals, air pollutants, and heavy metals. The purpose of this article is to shed light on the known effects of vaping on the ocular setting and raise the discussion about additional potential effects that may call for further investigation.

METHODS

A comprehensive literature search was conducted for publications pertaining to the effects of vaping on the eye. Relevant studies and findings were summarized in this article.

RESULTS

It was found that aldehydes and free radicals present in electronic cigarettes may induce a disturbance in tear film stability, and vape flavorings may damage the lipid layer through peroxidation. Corneal staining has been shown to appear following exposure to e-cigarette vapor, with nicotine and acrolein potentially inducing an inflammatory response in corneal epithelial cells. In addition, nicotine has been shown to induce nystagmus, exert vasoconstrictive effects on ocular blood flow, and may interfere with retinal light-adapted vision. Vape-related explosions, though unpredictable, may also result in decreased visual acuity along with long-term ocular trauma.

CONCLUSION

Research discussing both the short-term and long-term effects of vaping on the eye is limited. However, the potential harms of substances such as nicotine and aldehydes warrant additional investigation and increased education about the detriment that electronic cigarettes may inflict on sensitive organs.

Ocular injuries among oral and maxillofacial surgeons: Have high risk or not? An overview of a two-centered experience

BACKGROUND

Oral and maxillofacial surgeons are occupationally exposed to ocular injuries via bodily fluid (ie, blood or saliva), which can carry substantial latent risks, both bacterial and viral. The aim of this study was to determine the prevalence of ocular injury and infection among oral and maxillofacial surgeons during outpatient procedures.

METHODS

Data were collected from a consecutive series of 500 surgeries conducted by 26 resident surgeons via a questionnaire. Responses were categorized into two groups: Group I did not indicate an eye injury, and Group II did indicate an eye injury.

RESULTS

Of 500 procedures, 161 resulted in ocular injuries, a rate of 32.2 injuries per 100 person-procedures. Educated participants experienced eye injuries at a significantly higher rate than those who were uneducated (23.33% vs. 15.11%; P=0.022). Those not using eye protection experienced eye injuries at a significantly higher rate than those using eye protection (23.32% vs. 2.33%; P<0.001). Of all eye injuries, 14.28% required medical management. Incidents were reported at a rate of 10.56%, higher in those with multiple injuries.

CONCLUSION

These findings demonstrate major inadequacies and breaches of the present eye/face protection protocols. Because the number of clinical studies on ocular injuries during oral and maxillofacial surgerical procedures is limited in the literature, each additional study can be important for promoting awareness among professionals, so that serious morbidity can be prevented.

Effects of prolonged continuous computer gaming on physical and ocular symptoms and binocular vision functions in young healthy individuals

Background and Objective

Addiction to computer gaming has become a social problem in Korea and elsewhere, and it has been enlisted as a mental health disorder by the World Health Organization. Most studies related to computer use and vision have individually assessed physical and ocular symptoms and binocular vision. Accordingly, the present study comprehensively assessed subjective physical and ocular symptoms and functions related to binocular vision after prolonged continuous computer gaming. This study aimed to investigate the effects of prolonged continuous computer gaming on physical and ocular health and visual functions in young healthy individuals.

Methods

Fifty healthy college students (35 male/15 female), aged 19-35 years old, were enrolled in this study. The inclusion criteria were no binocular vision problems and no reported history of ocular disease. Participants played continuously for 4 h from 6:00 to 10:00 p.m. Physical and ocular symptoms and visual functions such as convergence, accommodation, phoria, and the blink rate were assessed before and after continuous computer gaming for 4 h.

Results

Continuous computer gaming for 4 h resulted in convergence and accommodation disturbances and increased physical and ocular discomfort. Near phoria showed an exophoric shift, whereas distance phoria showed no change. Moreover, the accommodative and vergence facilities and blink rate were significantly decreased. All visual functions recovered to the baseline levels by the following morning.

Discussion

Our findings suggest that excessive and continuous computer gaming impairs visual functions and causes ocular and physical fatigue. Our findings further the understanding of the adverse effects of excessive computer use on physical and ocular health, and adequate breaks are necessary to reduce physical and visual discomfort during computer gaming.

Influence of the breathing pattern during resistance training on intraocular pressure

This study aimed to assess the effect of the breathing pattern during resistance training on intraocular pressure (IOP). Twenty physically active collegiate students (7 women and 13 men) performed sets of 10 repetitions against the 10-RM (repetition maximum) load during the back-squat and biceps-curl exercises following 3 different breathing patterns: (I) Valsalva: holding the breath during the entire repetition; (II) normal breathing: holding the breath and exhaling during the first and second phases of the repetition, respectively; and (III) modified breathing: inhaling and holding the breath during the first and second phases of the repetition, respectively. Rebound tonometry was used to measure IOP before exercise, after each of the 10 repetitions, and after 1 min of recovery. The breathing pattern significantly affected the changes in IOP values (p < 0.001, [Formula: see text] = 0.509) with the normal breathing pattern providing lower increases in IOP values compared to the Valsalva (p < 0.001, d = 1.47) and modified breathing (p < 0.001, d = 0.96). Higher IOP values were observed for the back-squat compared to the biceps-curl exercise (p = 0.003, [Formula: see text] = 0.384). A normal breathing pattern should be recommended to avoid abrupt increments in IOP during resistance training. These findings may be especially important for individuals at high risk for glaucoma onset or progression due to the necessity of maintaining stable IOP levels to avoid the progression of this disease. In future studies, the inclusion of glaucoma patients would allow to assess the generalizability of these findings.

Introduction: Enigmas of Sphingolipids

Sphingolipid biology has enjoyed a remarkable rise to fame over the last two decades. Various molecules from this lipid family have been implicated in a variety of cellular functions in health and disease. Ceramides, which constitute the hub of sphingolipid metabolism, are apoptogenic molecules that have many proposed mechanisms of actions. Enigmas revolving around this area of research are slowly being cleared with the advent of better laboratory techniques and data analyses. In this chapter, a general introduction of the topics presented in this book is undertaken highlighting the main ideas of each chapter.

Fitness Level Modulates Intraocular Pressure Responses to Strength Exercises

Purpose/Aim: The execution of strength exercises has demonstrated to increase the intraocular pressure (IOP) levels, and it may have a negative impact on the ocular health. We aimed to explore the influence of fitness level on the acute IOP response to strength exercises performed under different loading conditions, as well as to test whether the IOP responses differ between the bench press and jump squat when performed against the same relative loads.

MATERIALS AND METHODS

Forty military personnel males were divided in two subgroups (20 high-fit and 20 low-fit) based on their relative to body mass one-repetition maximum (1-RM). Participants performed an incremental loading test in the bench press and jump squat exercises, and IOP was assessed before and after each repetition by rebound tonometry.

RESULTS

IOP increased immediately after executing both exercises (p < 0.01 in both cases), being the magnitude of the IOP increment positively and linearly associated with the increment of the load in both groups (i.e., high-fit and low-fit) and in both exercises (R² range: 0.81-1.00). Higher fitness level attenuated the IOP rise produced by both exercises (p < 0.01 in both cases). The bench press induced higher IOP increments than the jump squat for both groups at relative loads of ~50%1-RM and ~60%1-RM (p < 0.01 in all cases).

CONCLUSIONS

These data indicate that IOP increases as a consequence of performing strength exercises, being the increment accentuated with the increase of the load and in the bench press compared to the jump squat exercise. Of special importance would be that the IOP responses were significantly reduced in high-fit individuals. These findings should be addressed in glaucoma patients.