Accommodation-induced intraocular pressure changes in progressing myopes and emmetropes

Effect of spectacle correction on hyperopic children

Background: Hyperopia is a significant refractive error in children, often leading to vision impairment. This study aimed to investigate whether partial or full spectacle correction is benefit for hyperopia in preschool-aged children. Methods: A retrospective study was conducted on hyperopic children visited to teaching medical center outpatient clinic between October 2011 and October 2018, and were categorized into three groups: full correction, overcorrection, and undercorrection. The study was approved by the institutional ethical committee of Tri-Service General Hospital. Results: Following a minimum of one-year follow-up period, no statistically significant differences were observed in best-corrected visual acuity (BCVA) among children receiving full, over, or under spectacle correction. Notably, the overcorrection group exhibited a significant reduction in spherical equivalent (SE) compared to both the full and under correction groups, indicating a better SE with spectacle overcorrection. Conclusions: Spectacle overcorrection may offer potential benefits for enhancing SE in preschool children with hyperopia. Nevertheless, further investigation through randomized controlled trials is warranted to establish the validity of this approach and its impact on visual outcomes in this hyperopic pediatric population.

Models of myopia: the effect of accommodation, lenses and atropine

BACKGROUND

Two quantitative models for myopia have been proposed and used for myopic intervention, one derived from feedback theory, and the other from physiological and mechanical considerations. This paper shows that they both predict the same results indicating that they are valid and reliable. These models are the only ones that can make predictions about the effect of atropine and lenses on myopia, explain multiple observations heretofore unexplained and offer possible interventions.

OBJECTIVE

Using their predictive power we test the models by calculating and comparing the effect of accommodation, lenses or atropine. The models offer a rationale that makes atropine equivalent to a positive lens for purposes of refractive development.

METHODS

This report includes thought experiments, actual experiments and trials, as well as an analysis of clinical data and integrates and tests results from all of them for far-reaching conclusions.

RESULTS

Both models accurately predict the same myopia progression caused by near work. These models are simple but powerful enough to suggest what treatments are indicated. Interventions for prevention and control of myopia are evaluated analytically, in particular atropine and optical treatments, such as positive lenses and under correction.

CONCLUSION

Optical treatments have enormous potential; atropine is of questionable value since there are ways to get the same or superior effect with lenses of power calculated as described here.

Intraocular Pressure Changes While Reading Smartphone Digital Text Versus Printed Text in Healthy Individuals and those with Glaucoma

PRCIS

Reading results in a rise in intraocular pressure (IOP) which is greater while using smartphones compared with printed text among healthy and individuals with medically controlled primary open angle glaucoma (POAG).

PURPOSE

To compare the effect of reading for 30 minutes using smartphone and printed text on IOP.

PATIENTS AND METHODS

Sixty healthy volunteers and 22 patients with medically controlled POAG were asked to perform reading tasks using printed text followed by digital (smartphone) text under standardized conditions. IOP assessment was done using a rebound tonometer at baseline and subsequently at 10, 20, and 30 minutes of reading and 10 and 20 minutes post completion of reading tasks. IOP variations from baseline were measured and compared. Paired and independent ' T ' test analysis was performed to study IOP variations, and a P -value <0.05 was considered statistically significant.

RESULTS

The mean baseline IOP among volunteers and patients withPOAG was 14.58 (±2.91) and 15.02 (±2.18) mmHg, respectively. There was a rise in IOP in all participants with reading using either of the modalities, which normalized after 20 minutes of cessation. There was a statistically significant difference in rise in IOP from baseline between the 2 modalities (printed text reading and smartphone reading) at 20 minutes {+0.78 & +2.01 ( P =0.002)} and 30 minutes {+0.64 & +1.72 ( P =0.004)} among healthy volunteers and at 20 minutes {+0.78 & +2.01 ( P =0.002)} among POAG patients.

CONCLUSION

Reading is associated with the rise in IOP in both healthy volunteers and POAG individuals. The IOP rise is more marked with smartphone compared with printed text reading.

Anterior Segment Biometry During Accommodation After Posterior Chamber Phakic Implantable Collamer Lens Implantation

PURPOSE

To evaluate the dynamic changes in anterior segment parameters during accommodation following Implantable Collamer Lens (ICL) implantation with swept-source optical coherence tomography (SS-OCT).

METHODS

Under the accommodation of 0.00 diopters (D), 3.00 D, and maximum amplitude, SS-OCT was used to examine the anterior segment parameters, including ICL vault, ICL depth (the distance between the corneal endothelium and the posterior surface of ICL), crystalline lens thickness, anterior chamber depth, and various parameters of the anterior chamber angle, comprising angle opening distance, angle recess area, trabecular iris space area, and trabecular iris angle.

RESULTS

During accommodation, the ICL vault showed a significant decrease from baseline (536 ± 278 μm) to 3.00 D (522 ± 281 μm), followed by an increase from 3.00 D to maximum amplitude (548 ± 306 μm) (analysis of variance [ANOVA], P < .001). Four eyes (2.61%) exhibited a decrease in ICL vault to less than 100 μm (47 ± 32 μm) at maximum accommodation. The ICL depth decreased significantly as accommodation increased (ANOVA, P < .001). Crystalline lens thickness increased, whereas anterior chamber depth decreased during accommodation (ANOVA, P < .001). The anterior chamber angle widened during 3.00 D of accommodation but narrowed at maximum accommodation, leading to significant changes in the angle opening distance, angle recess area, trabecular iris space area, and trabecular iris angle during accommodation (ANOVA, P < .001 for all).

CONCLUSIONS

The anterior segment, including ICL vault and anterior chamber angle, undergo significant dynamic changes during accommodation. These accommodative changes may require careful monitoring for the surgery design of ICL implantation. [J Refract Surg. 2024;40(3):e164-e172.].

Intraocular Pressure and Myopia Progression, Axial Length Elongation in Rural Chinese Children

SIGNIFICANCE

This study reported the relationship between intraocular pressure (IOP) and myopia progression, which helps to understand more comprehensively whether IOP can be an important reference factor to intervene in the progression of myopia.

PURPOSE

This study aimed to investigate the association between IOP and myopia progression as well as axial length elongation in rural Chinese children.

METHODS

A total of 598 (598 of 878 [68.1%]) children (6 to 17 years) from the baseline Handan Offspring Myopia Study who completed a 3.5-year follow-up vision examination were included. Ocular examinations at both visits included cycloplegic autorefraction, IOP, and axial length measurements.

RESULTS

Children with myopia had the highest baseline IOP of the three refractive groups (14.13 ± 1.31, 13.78 ± 1.71, and 13.59 ± 1.64 mmHg in myopes, emmetropes, and hyperopes, respectively, P = .002). However, IOPs showed no significant difference between eyes with or without newly developed myopia (13.63 ± 1.68 vs. 13.89 ± 1.68, P = .16), with or without faster myopia progression (13.75 ± 1.61 vs. 13.86 ± 1.63, P = .46), or with axial length elongation (13.80 ± 1.61 vs. 13.76 ± 1.64, P = .80). The multivariate regression analysis demonstrated that neither baseline refractive error ( β = -0.082, P = .13) nor baseline axial length ( β = -0.156, P = .08) was associated with baseline IOP.

CONCLUSIONS

Myopic eyes have slightly higher IOP compared with emmetropic and hyperopic eyes, although it was not clinically significant. However, IOP was not found to be associated with either myopia progression or axial length elongation in this cohort sample of rural Chinese children.

The Influence of Near Vision Tasks on Intraocular Pressure in Normal Subjects and Glaucoma Patients

Purpose

To investigate the effect of static accommodative tasks on intraocular pressure (IOP) of glaucomatous and normal eyes.

Methods

Four groups of subjects categorized as primary open-angle glaucoma (POAG), primary angle-closure suspects (PACS), normal age-matched controls, and normal young adults (NYA; age < 40 years) were enrolled. The baseline IOPs were measured after the subjects were looking at a distant target for 15 min. Static accommodation was obtained by execution of near vision tasks (reading at 33 cm in daylight [300 lux] for 60 min). IOPs were measured at 15, 30, 45, and 60 min intervals while accommodating and then measured again after 15 min of relaxing accommodation while looking at a distant target.

Results

One-hundred and eighteen eyes of 98 subjects were recruited. The study groups consisted of the following categories: 25 POAG (46 eyes), 24 PACS (47 eyes), 25 matched controls (50 eyes), and 24 NYA (48 eyes). Within all groups, the mean IOP decreased throughout the accommodation period at all time points. Maximum IOP reduction after accommodation was detected at the 30-min time among the POAG subjects, at the 45-min time in the PACS and matched control groups, and at 15 min after the relaxation of accommodation in the NYA group. IOP reduction levels showed no statistically significant difference among POAG, PACS, and the normal matched groups in their response to accommodation. However, NYA had significantly lower IOP and greater IOP reduction after the resting period (relaxation of accommodation).

Conclusion

Static accommodative tasks can significantly reduce IOP in normal, POAG, and PACS individuals. Encouraging glaucoma patients to practice periodical near vision tasks could be viewed as an adjunctive measure for glaucoma management.

Short-Term Exposure to Violet Light Emitted from Eyeglass Frames in Myopic Children: A Randomized Pilot Clinical Trial

Violet light (VL), 360−400 nm wavelength, is contained in the sunlight and is an effective element for myopia suppression. This study is to investigate the safety and efficacy of novel eyeglasses that emit VL from the frames. This is a double-masked, randomized, pilot clinical trial conducted in a clinic in Japan. Forty-three children with myopia were enrolled. Participants were randomly assigned to two groups, wearing VL-emitting eyeglass frames (VLf) that emitted VL of 310 μW/cm2 (VLf group, n = 22) or pseudo-placebo eyeglass frames with a minimal emission of VL (<10 μW/cm2) (control group, n = 21). The exposure time was 3 h per day. The primary outcomes were visual acuity, tear film break-up time, corneal endothelial cell density, and the slit-lamp/fundus examinations. The secondary outcome was the 6-month changes in the axial lengths and cycloplegic refractions. Forty-one (95%) participants were included; twenty-one in the VLf group and twenty in the control group. No significant differences were seen in any safety evaluation. Significant changes were seen in axial elongation, choroidal thickness, and cycloplegic refractions in the subgroup analysis of 8- to 10-year-old children (p < 0.05), but otherwise no significant differences were seen. The VLf showed short-term safety and effectiveness against myopia progression.

A Review of Intraocular Pressure (IOP) and Axial Myopia

The pathogenesis of myopia is driven by genetic and environmental risk factors. Accommodation not only alters the curvature and shape of the lens but also involves contraction of the ciliary and extraocular muscles, which influences intraocular pressure (IOP). Scleral matrix remodeling has been shown to contribute to the biomechanical susceptibility of the sclera to accommodation-induced IOP fluctuations, resulting in reduced scleral thickness, axial length (AL) elongation, and axial myopia. The rise in IOP can increase the burden of scleral stretching and cause axial lengthening. Although the accommodation and IOP hypotheses were proposed long ago, they have not been validated. This review provides a brief and updated overview on studies investigating the potential role of accommodation and IOP in myopia progression.

Variations in intraocular pressure and visual parameters before and after using mobile virtual reality glasses and their effects on the eyes

We examined the effects of using mobile devices with immersive virtual reality for a short period on the physiological parameters of both eyes. The average age of the 50 participants (23 men and 27 women) was 17.72 ± 1.48 years, and refractive error ranged from 0 D to − 5.00 D. All the participants wore + 3.00 D glasses and underwent a 5-min relaxation adjustment through the atomization method. The participants wore immersive virtual reality (VR) glasses to watch a movie on a roller coaster for 10 min. Their relevant physiological parameters of the eyes were measured both before and after using VR glasses. Compared with before VR use, no significant difference (P > 0.05) was observed in the near-horizontal vergence and refractive error but a significant difference (P < 0.05) was observed in the amplitude of accommodation, intraocular pressure, divergence/convergence, and stereopsis after VR use. The corneal elastic coefficient was > 0.2 MPa, and we used Friedenwald’s eye rigidity relationship to obtain the K value (0.065–0.09). Approximately 10% of the participants experienced cybersickness symptoms such as nausea and dizziness. The use of VR to watch three-dimensional movies reduced intraocular pressure, which may help prevent or treat glaucoma. Moreover, the binocular convergence was higher when viewing near-field objects in VR than in the real world. Therefore, individuals with convergence excess may experience symptoms. Binocular parallax is the most likely cause of cybersickness symptoms. Thus, mobile VR devices with higher quality and comfort are necessary.

Single-vision spectacle use and myopia progression in children with low myopia, a propensity score matching study

Purpose

To investigate the impact of single-vision spectacle use on myopia progression in children with low myopia.

Methods

MYOSOTIS is a prospective myopia screening survey including all 46 primary and junior high schools in two districts of Hangzhou, China. After 1-to-1 propensity score matching (PSM), 1,685 pairs of students with low myopia were included. Group 1 was composed of 1,685 non-spectacle users at baseline, and group 2 consisted of 1,685 spectacle wearers at both survey rounds. Refraction was examined by noncycloplegic autorefraction and mean spherical equivalent refraction (SER) of both eyes was analyzed. Myopia progression was measured by average rate of change in SER (r∆SER) between two survey rounds and compared between the two groups.

Results

After PSM, no significant difference in age, sex ratio, SER, and uncorrected visual acuity (VA) between the two groups was found at baseline. For myopic progression, r∆SER showed no significant difference between the two groups (− 0.67 ± 0.97 versus − 0.69 ± 0.81 diopter/year, P = 0.448). After adjusting for age, sex, SER, and VA, the difference in r∆SER between the two groups was not significant (− 0.031, 95% CI − 0.089 ~ 0.028 diopter/year, P = 0.302). In the subgroup analyses stratified by age and SER, and in the sensitivity analyses by eye side, there was still no significant difference in myopia progression between the two groups.

Conclusions

Our study indicates that single-vision spectacle use has no impact on myopia progression in children with low myopia. Spectacles are recommended in children with low myopia if their visual acuity has interfered with the daily life.

Supplementary Information

The online version contains supplementary material available at 10.1007/s00417-021-05423-6.

Changes in Iridocorneal Angle Configuration and Intraocular Pressure during Smartphone Use under Room Light

Purpose: To investigate changes in intraocular pressure (IOP) and iridocorneal angle (ICA) configuration during smartphone use under room light. Methods: We included healthy adults aged 19-35 years with no ophthalmological abnormalities. All read text on a smartphone for 6 minutes under room light. IOP was measured via rebound tonometry at baseline and at 2, 4, and 6 minutes. ICA images were obtained via anterior segment optical coherence tomography after each IOP measurement. After 6 minutes, participants stopped reading text and rested for 2 minutes. IOP was then measured again. Results: The IOP significantly increased at 2, 4, and 6 minutes of reading compared to baseline (<i>p</i> < 0.001) but recovered to baseline after 2 minutes of rest (<i>p</i> = 1.000). The anterior chamber depth decreased significantly, and the anterior chamber angle width increased after 6 minutes of smartphone reading (both <i>p</i> < 0.05). Conclusions: IOP increased when reading smartphone text under room light but the ICA did not change. Prolonged smartphone reading is inappropriate for a patient at risk of glaucoma or glaucoma progression. Such patients should be cautioned.

Roles of the ocular pressure, pressure-sensitive ion channel, and elasticity in pressure-induced retinal diseases

The intraocular pressure inside the human eye maintains 10–21 mmHg above the atmospheric pressure. Elevation of intraocular pressure is highly correlated with the retinopathy in glaucoma, and changes in the exterior pressure during mountain hiking, air traveling, and diving may also induce vision decline and retinopathy. The pathophysiological mechanism of these pressure-induced retinal disorders has not been completely clear. Retinal neurons express pressure-sensitive channels intrinsically sensitive to pressure and membrane stretch, such as the transient receptor potential channel (TRP) family permeable to Ca²⁺ and Na⁺ and the two-pore domain K channel family. Recent data have shown that pressure excites the primate retinal bipolar cell by opening TRP vanilloid 4 to mediate transient depolarizing currents, and TRP vanilloid 4 agonists enhance the membrane excitability of primate retinal ganglion cells. The eyeball wall is constructed primarily by the sclera and cornea of low elasticity, and the flow rate of the aqueous humor and intraocular pressure both fluctuate, but the mathematical relationship between the ocular elasticity, aqueous humor volume, and intraocular pressure has not been established. This review will briefly review recent literature on the pressure-related retinal pathophysiology in glaucoma and other pressure-induced retinal disorders, the elasticity of ocular tissues, and pressure-sensitive cation channels in retinal neurons. Emerging data support the global volume and the elasticity and thickness of the sclera and cornea as variables to affect the intraocular pressure level like the volume of the aqueous humor. Recent results also suggest some potential routes for TRPs to mediate retinal ganglion cell dysfunction: TRP opening upon intraocular pressure elevation and membrane stretch, enhancing glutamate release from bipolar cells, increasing intracellular Na⁺, Ca²⁺ concentration in retinal ganglion cells and extracellular glutamate concentration, inactivating voltage-gated Na⁺ channels, and causing excitotoxicity and dysfunction of retinal ganglion cells. Further studies on these routes likely identify novel targets and therapeutic strategies for the treatment of pressure-induced retinal disorders.

Accommodative Exercises to Lower Intraocular Pressure

Purpose

This study investigated how a conscious change in ocular accommodation affects intraocular pressure (IOP) and ocular biometrics in healthy adult volunteers of different ages.

Methods

Thirty-five healthy volunteers without ocular disease or past ocular surgery, and with refractive error between −3.50 and +2.50 diopters, were stratified into 20, 40, and 60 year old (y.o.) age groups. Baseline measurements of central cornea thickness, anterior chamber depth, anterior chamber angle, cornea diameter, pupil size, and ciliary muscle thickness were made by autorefraction and optical coherence tomography (OCT), while IOP was measured by pneumotonometry. Each subject's right eye focused on a target 40 cm away. Three different tests were performed in random order: (1) 10 minutes of nonaccommodation (gazing at the target through lenses that allowed clear vision without accommodating), (2) 10 minutes of accommodation (addition of a minus 3 diopter lens), and (3) 10 minutes of alternating between accommodation and nonaccommodation (1-minute intervals). IOP was measured immediately after each test. A 20-minute rest period was provided between tests. Data from 31 subjects were included in the study. ANOVA and paired t-tests were used for statistical analyses.

Results

Following alternating accommodation, IOP decreased by 0.7 mmHg in the right eye when all age groups were combined (p = 0.029). Accommodation or nonaccommodation alone did not decrease IOP. Compared to the 20 y.o. group, the 60 y.o. group had a thicker ciliary muscle within 75 μm of the scleral spur, a thinner ciliary muscle at 125–300 μm from the scleral spur, narrower anterior chamber angles, shallower anterior chambers, and smaller pupils during accommodation and nonaccommodation (p's < 0.01).

Conclusion

Alternating accommodation, but not constant accommodation, significantly decreased IOP. This effect was not lost with aging despite physical changes to the aging eye. A greater accommodative workload and/or longer test period may improve the effect.

Acute Intraocular Pressure Responses to Reading: The Influence of Body Position

PRéCIS:: Greater intraocular pressure (IOP) values are observed when reading in the supine position in comparison with the sitting position, and thus, it should be considered by eye care specialists for the management of glaucoma patients or those at risk.

PURPOSE

IOP is sensitive to near work and body position, however, the influence of the body position adopted while performing near tasks remains unknown. This study aimed to assess the IOP changes induced by reading on a smartphone in sitting and supine position, and to explore whether these IOP changes differ between men and women.

METHODS

Twenty-four healthy young adults (12 men and 12 women) read a text on a smartphone placed at 30 cm for 25 minutes while lying down and sitting in 2 different days. A rebound tonometer, which allows assessing IOP in the supine position, was used to measure IOP before reading, during reading (5, 15, and 25 min), and after 5 minutes of recovery. Complementarily, the authors checked the level of sleepiness/alertness before reading, and the perceived levels of fatigue and discomfort after reading.

RESULTS

The data showed that reading induces an IOP rise [P<0.001, partial eta squared (ηp)=0.44]. These effects were more accentuated when reading in the supine position in comparison with the sitting position (P=0.019, ηp=0.23) with an increment of 2.4 mm Hg (14%) and 1.3 mm Hg (8%) after 25 minutes of reading, respectively. The IOP rises associated with reading did not differ between men and women (P=0.127). Participants reported greater levels of discomfort in the neck and back when reading in the sitting position (P=0.012, ηp=0.25).

CONCLUSIONS

The IOP rises associated with reading are greater when it is performed in the supine position in comparison with the sitting position. The present findings indicate that reading in the supine position should be discouraged in individuals who should avoid IOP increments or fluctuations.

Smartphones and vision

Many people spend too much time using their smartphones. Contrast, small screen size, resolution, image repetition frequency and screen reflection will cause characteristic ocular symptoms. The objective of this study is to describe the ophthalmological symptoms in persons who spend a large number of hours using electronic devices. For this purpose, a search was conducted in the Pubmed and MED line database to find the appropriate articles. The most frequent ocular manifestation after prolonged use of smartphones without care for eye hygiene were ocular complaints, such as tiredness, eye irritation, blurred vision and transient, but marked elevated intraocular pressure. Early and adequate recognition of ophthalmic symptoms that may be associated with the using smartphones for many hours and the implementation of appropriate management can protect against the occurrence of late complications in the form of permanent eye damage.

Effect of Near Work on Intraocular Pressure in Emmetropes

Objective

To determine whether accommodation induced by reading alters intraocular pressure (IOP) in healthy, young, emmetropic adults and to document the duration and magnitude of this effect.

Design

Cross-sectional study. Participants. Fifteen healthy, emmetropic young adults.

Methods

Subjects performed 20 minutes of near work (reading at 33 cm) followed by 20 minutes of far work (reading at 520 cm) while IOP was measured using an iCare tonometer at baseline and every 5 minutes thereafter. Statistical analysis was performed using repeated measures ANOVA. Main Outcome Measures. Intraocular pressure.

Results

IOP decreased significantly compared to baseline IOP after 10 minutes of near work (average change of −1.60 ± 2.2 (SD) mm Hg, p < 0.05). IOP remained lower than baseline IOP throughout all subsequent near and far work. The difference in IOP at the end of experimentation compared to baseline IOP was −1.87 ± 1.81 mm Hg (p < 0.05). IOP remained lower than baseline IOP throughout all subsequent near and far work. The difference in IOP at the end of experimentation compared to baseline IOP was −1.87 ± 1.81 mm Hg (

Conclusions

Near work decreases IOP in healthy emmetropes, and this effect is sustained for at least 20 minutes after discontinuing prolonged near work. Providers may need to consider this effect when measuring IOP in clinical practice.

Ocular Accommodation, Intraocular Pressure, Development of Myopia and Glaucoma: Role of Ciliary Muscle, Choroid and Metabolism

Ocular accommodation is not just a mechanism for altering curvature of the crystalline lens of the eye, it also enables aqueous humor outflow through the trabecular meshwork, influencing intraocular pressure (IOP). Long term stress on the ciliary muscle from sustained near focusing may initiate myopic eye growth in children and primary open angle glaucoma in presbyopic adults. Multi-factorial studies of ocular accommodation that include measures of IOP, ciliary muscle morphology, anterior chamber depth and assessment of nutritional intake and metabolic markers may elucidate etiology and novel strategies for management of both myopia and chronic glaucoma. Anatomy of the ciliary fibers from anterior insertion in the fluid drainage pathway to their posterior consanguinity with the vascular choroid, alters ocular parameters such as micro-fluctuations of accommodation and pulsatile ocular blood flow that are driven by cardiac contractions conveyed by carotid arteries. Stretching of the choroid has consequences for thinning of the peripheral retina, sclera and lamina cribrosa with potential to induce retinal tears and optic nerve cupping. Early metabolic interventions may lead to prevention or reduced severity of myopia and glaucoma. Finally, it might improve quality of life of patients and decrease disability from visual impairment and blindness.

Effect of Smartphone Use on Intraocular Pressure

The rapidly increasing utilization of smartphones makes ophthalmic problems associated with their use an important issue. This prospective study aimed to determine whether using a smartphone to view visual material is associated with a change in the intraocular pressure (IOP), and to determine which groups of factors best predict the time-dependent increase in IOP with smartphone use. This study included 158 eyes (127 glaucomatous and 31 healthy eyes) recruited from Seoul National University Bundang Hospital. Participants performed a sustained fixation task consisting of watching a movie on a smartphone screen for 30 minutes continuously at a viewing distance of 30 cm. A small but statistically significant time-dependent increase in IOP was observed while viewing a movie on a smartphone, being 10.6 ± 3.1, 11.0 ± 3.3, 11.2 ± 3.4, and 11.6 ± 3.5 mmHg before and 5, 10, and 30 minutes after the fixation task, respectively (P < 0.0001). Recursive partitioning tree analysis revealed that a shallower anterior chamber (<2.32 mm) was the strongest predictive factor for faster time-dependent increase in IOP (0.68 mmHg/minute). A higher visual field mean deviation (≥-0.22 dB), and an older age (≥48 years) were the second and third most influential factors associated with the rate of IOP increase (0.59 and 0.15 mmHg/minute, respectively).

Changes in intraocular pressure during reading or writing on smartphones in patients with normal-tension glaucoma

BACKGROUND/AIMS

To investigate (1) the effect of reading or writing on a smartphone in terms of intraocular pressure (IOP) change in eyes with glaucoma, and (2) to determine whether previous glaucoma filtering surgery can affect IOP fluctuation during such work.

METHODS

Forty eyes of 40 medically well IOP-controlled normal-tension glaucoma (NTG) patients and 38 eyes of 38 NTG patients who had undergone successful trabeculectomy (TLE) were enrolled. The participants were instructed to read a sample text and to then type it on a smartphone under low-light [100 lux] conditions. Three IOP measurements were obtained: baseline; during smartphone work (5, 15 and 25 min); post-work (5 and 15 min).

RESULTS

Baseline IOP did not significantly differ between the two groups (medication group: 13.9±1.6 mm Hg; TLE group: 13.6±1.7 mm Hg; p=0.426). After 5 min of smartphone work, the medication group showed significantly elevated mean IOP (15.5±1.8 mm Hg;+11.5%; p<0.001), along with further increases over the course of 25 min (17.5±2.2 mm Hg;+25.9%; p<0.001). 5 min after halting work, IOP dropped below the baseline (13.1±1.7 mm Hg; p<0.001). For the TLE group, IOP also was elevated after 5 min (14.9±1.7 mm Hg;+9.4%; p<0.001); however, it did not show further increase over the course of 25 min of work (15.0±1.6 mm Hg;+10.3%). At 5 min after cessation of work, IOP had restored to the pre-work level (14.0±1.9 mm Hg;+2.8%; p=0.053).

CONCLUSION

Working on a smartphone under low-light condition can incur IOP elevation in treated NTG patients. However, among the participants in this study, IOP fluctuation was much smaller in those who had undergone TLE.

Current and emerging pharmaceutical interventions for myopia

Myopia is a major cause of visual impairment. Its prevalence is growing steadily, especially in East Asia. Despite the immense disease and economic burden, there are currently no Food and Drug Administration-approved drugs for myopia. This review aims to summarise pharmaceutical interventions of myopia at clinical and preclinical stages in the last decade and discuss challenges for preclinical myopia drugs to progress to clinical trials. Atropine and oral 7-methylxanthine are shown to reduce myopia progression in human studies. The former has been extensively studied and is arguably the most successful medication. However, it has side effects and trials on low-dose atropine are ongoing. Other pharmaceutical agents being investigated at a clinical trial level include ketorolac tromethamine, oral riboflavin and BHVI2 (an experimental drug). Since the pathophysiology of myopia is not fully elucidated, numerous drugs have been tested at the preclinical stage and can be broadly categorised based on the proposed mechanisms of myopisation, namely antimuscarinic, dopaminergic, anti-inflammatory and more. However, several agents were injected intravitreally or subconjunctivally, hindering their progress to human trials. Furthermore, with atropine being the most successful medication available, future preclinical interventions should be studied in combination with atropine to optimise the treatment of myopia.

Intraocular pressure change during reading or writing on smartphone

Purpose

To investigate the effect of reading or writing on a smartphone in terms of intraocular pressure (IOP) changes.

Design

Prospective, comparative case series.

Participants

Thirty-nine (39) healthy young (age < 40) volunteers.

Methods

The participants were requested to conduct standardized work (i.e., read a sample text on single mobile device and subsequently type it on the same device) under daylight [300 lux] and low-light [100 lux] conditions independently on consecutive days. On each day, three sets of IOP measurements (total: 7) using a rebound tonometer (iCare PRO; Tiolat, Helsinki, Finland) were performed: (1) pre-work (baseline) [2 measurements], (2) during smartphone work [5, 15, and 25 minutes], and (3) post-work [5 and 15 minutes].

Main outcome measures

Changes in IOP at different check-out points.

Results

Under the daylight condition, the mean baseline IOP was 13.7 ± 1.8 mmHg, and the mean IOP increased after 5 minutes of work (14.1 ± 1.8 mmHg; +2.0 ± 1.9%; P < 0.001). When the smartphone work lasted for 15 minutes, the IOP showed a further significant increase (15.5 ± 1.7 mmHg; +12.9 ± 4.4%; P < 0.001), which persisted over the course of the 25 minutes of smartphone work (15.3 ± 1.8 mmHg; +11.1 ± 3.9%; P < 0.001); then, after stopping work for 5 minutes, the IOP was restored (13.9 ± 1.7 mmHg; +0.9 ± 2.1%; P = 0.220). Under the low-light condition, the mean IOP was significantly increased immediately after 5 minutes of smartphone work (from 13.9 ± 1.9 to 15.6 ± 1.8 mmHg; +12.1 ± 4.8%; P < 0.001); this IOP increase continued: 17.3 ± 1.9 [+24.7 ± 10.3%] at 15 minutes’ work, and 17.0 ± 1.7 mmHg [+23.1 ± 9.5%] at 25 minutes’ work (P < 0.001 at both check-out points). Five minutes after stopping the smartphone work, interestingly, the IOP significantly dropped, to a level even lower than that of the pre-work (12.8 ± 1.9 mmHg; -8.1 ± 3.0%; P < 0.001), and at post-work 15 minutes, the IOP returned to the baseline (13.9 ± 1.8 mmHg; -0.3 ± 2.6%; P = 0.360).

Conclusions

In healthy young subjects, reading or writing on smartphone significantly increased IOP, and the changes of IOP were faster and greater under the low-light condition. Smartphone users who are concerned about IOP fluctuation are advised to (1) take a break if they read or write on smartphone for more than 5 minutes, and (2) avoid using smartphones wherever possible in dark places.

Dynamic Changes in Schlemm Canal and Iridocorneal Angle Morphology During Accommodation in Children With Healthy Eyes: A Cross-Sectional Cohort Study

Purpose

The purpose of this study was to explore changes in Schlemm canal (SC), trabecular meshwork (TM), and iridocorneal angle (ICA) morphology during accommodative effort in children and young adults.

Methods

We acquired anterior segment optical coherence tomography images (AS-OCT) of the ICA and ciliary muscle (CM) of both eyes of 50 children age 4 to 16 years with healthy eyes, at two levels of accommodation: 2.5 and 15 diopters (D). Semiautomated nasal ICA measurements were as follows: angle opening distance at 500/750 μm (AOD-500, -750), trabecular iris space area at 500/750 μm (TISA-500, -750), and trabecular iris angle at 500/750 μm (TIA-500, -750). Manual measurements were as follows: anteroposterior and radial SC diameter (SC-APD, SC-RD), cross-sectional area of SC (SC-CSA) and TM height (TMH), TM length (TML), and TM density (TMD). CM width was measured at 1, 2, and 3 mm from the scleral spur (CM-1, CM-2, CM-3). For each parameter, a three-level random-effects model was fitted to estimate differences between the two levels of accommodation.

Results

With accommodative effort, SC diameters and CSA increase significantly, as do TM length and iridocorneal angle parameters. With increasing age, SC dimensions reduce. Angle parameters are smaller in eyes with greater spherical equivalent (hypermetropia).

Conclusions

AS-OCT can be used to visualize dynamic morphologic changes in outflow structures with physiologic accommodation. The increase in SC dimensions with accommodative effort may contribute to the regulation of IOP in children.

α-adrenergic agonist brimonidine control of experimentally induced myopia in guinea pigs: A pilot study

PURPOSE

To investigate the efficacy of α-adrenergic agonist brimonidine either alone or combined with pirenzepine for inhibiting progressing myopia in guinea pig lens-myopia-induced models.

METHODS

Thirty-six guinea pigs were randomly divided into six groups: Group A received 2% pirenzepine, Group B received 0.2% brimonidine, Group C received 0.1% brimonidine, Group D received 2% pirenzepine + 0.2% brimonidine, Group E received 2% pirenzepine + 0.1% brimonidine, and Group F received the medium. Myopia was induced in the right eyes of all guinea pigs using polymethyl methacrylate (PMMA) lenses for 3 weeks. Eye drops were administered accordingly. Intraocular pressure was measured every day. Refractive error and axial length measurements were performed once a week. The enucleated eyeballs were removed for hematoxylin and eosin (H&E) and Van Gieson (VG) staining at the end of the study.

RESULTS

The lens-induced myopia model was established after 3 weeks. Treatment with 0.1% brimonidine alone and 0.2% brimonidine alone was capable of inhibiting progressing myopia, as shown by the better refractive error (p=0.024; p=0.006) and shorter axial length (p=0.005; p=0.0017). Treatment with 0.1% brimonidine and 0.2% brimonidine combined with 2% pirenzepine was also effective in suppressing progressing refractive error (p=0.016; p=0.0006) and axial length (p=0.017; p=0.0004). The thickness of the sclera was kept stable in all groups except group F; the sclera was much thinner in the lens-induced myopia eyes compared to the control eyes.

CONCLUSIONS

Treatment with 0.1% brimonidine alone and 0.2% brimonidine alone, as well as combined with 2% pirenzepine, was effective in inhibiting progressing myopia. The result indicates that intraocular pressure elevation is possibly a promising mechanism and potential treatment for progressing myopia.

Serum 25-hydroxyvitamin D level is associated with myopia in the Korea national health and nutrition examination survey

The aim of this article was to assess the associations of serum 25-hydroxyvitamin D [25(OH)D] and daily sun exposure time with myopia in Korean adults.This study is based on the Korea National Health and Nutrition Examination Survey (KNHANES) of Korean adults in 2010-2012; multiple logistic regression analyses were performed to examine the associations of serum 25(OH)D levels and daily sun exposure time with myopia, defined as spherical equivalent ≤-0.5D, after adjustment for age, sex, household income, body mass index (BMI), exercise, intraocular pressure (IOP), and education level. Also, multiple linear regression analyses were performed to examine the relationship between serum 25(OH)D levels with spherical equivalent after adjustment for daily sun exposure time in addition to the confounding factors above.Between the nonmyopic and myopic groups, spherical equivalent, age, IOP, BMI, waist circumference, education level, household income, and area of residence differed significantly (all P < 0.05). Compared with subjects with daily sun exposure time <2 hour, subjects with sun exposure time ≥2 to <5 hour, and those with sun exposure time ≥5 hour had significantly less myopia (P < 0.001). In addition, compared with subjects were categorized into quartiles of serum 25(OH)D, the higher quartiles had gradually lower prevalences of myopia after adjustment for confounding factors (P < 0.001). In multiple linear regression analyses, spherical equivalent was significantly associated with serum 25(OH)D concentration after adjustment for confounding factors (P = 0.002).Low serum 25(OH)D levels and shorter daily sun exposure time may be independently associated with a high prevalence of myopia in Korean adults. These data suggest a direct role for vitamin D in the development of myopia.

Intraocular Pressure Changes during Accommodation in Progressing Myopes, Stable Myopes and Emmetropes

Purpose

To investigate the changes of intraocular pressure (IOP) induced by 3-diopter (3 D) accommodation in progressing myopes, stable myopes and emmetropes.

Design

Cross-sectional study.

Participants

318 subjects including 270 myopes and 48 emmetropes.

Methods

195 progressing myopes, 75 stable myopes and 48 emmetropes participated in this study. All subjects had their IOP measured using iCare rebound tonometer while accommodative stimuli of 0 D and 3 D were presented.

Main Outcome Measures

IOP values without accommodation and with 3 D accommodation were measured in all subjects. Baseline IOPs and IOP changes were compared within and between groups.

Results

There was no significant difference in IOPs between progressing myopes, stable myopes and emmetropes when no accommodation was induced (17.47±3.46, 16.62±2.98 and 16.80±3.62 respectively, p>0.05). IOP experienced an insignificantly slight decrease after 3 D accommodation in three groups (mean change -0.19±2.16, -0.03±1.68 and -0.39±2.65 respectively, p>0.05). Subgroup analysis showed in progressing myopic group, IOP of children (<18 years old) declined with accommodation while IOP of adults (≥18 years) increased, and the difference was statistically significant (p = 0.008). However, after excluding the age factor, accommodation induced IOP changes of high progressing myopes (≤-6 D), low, moderate and non-myopes (>-6 D) was not significantly different after Bonferroni correction (p = 0.838).

Conclusions

Although no difference was detected between the baseline IOPs and accommodation induced IOP changes in progressing myopes, stable myopes and emmetropes, this study found accommodation could cause transient IOP elevation in adult progressing myopes.