The association between visual impairment and mental disorders.

To determine the association between visual impairment (VI) and some mental disorders using the general health questionnaire (GHQ) in individuals aged 60 years and above in Tehran, Iran. The present population-based cross-sectional study was conducted on people aged 60 and older in Tehran, Iran using multi-stage cluster sampling. After selecting the samples, examinations including visual acuity measurement, refraction, and slit-lamp biomicroscopy were performed for all participants. The GHQ was used to examine mental disorders. Simple and multiple linear regressions were used to investigate the association between VI and mental disorders. Of the 3740 invitees, 3310 participated in the study (response rate: 88.50%). After applying the exclusion criteria, 2789 individuals were analyzed for this report. Mean score of physical, anxiety, social and depression disorders in people with and without VI was 3.74 ± 2.03, 5.81 ± 2.79, 7.56 ± 1.91, 1.32 ± 1.90, and 3.14 ± 1.76, 4.93 ± 2.71, 8.09 ± 1.99, 0.91 ± 1.38, respectively. The total score of GHQ in participants with and without VI was 18.43 ± 4.75 and 17.07 ± 4.19, respectively. The association between GHQ subscales and total GHQ score with VI by multiple linear regression showed that VI had a statistically significant direct association with physical symptoms (ß = 0.37; 95% CI 0.12 to 0.62) and anxiety (ß = 0.48; 95% CI 0.16 to 0.81). Nevertheless, depression had a borderline association with VI (ß = 0.21; 95% CI - 0.03 to 0.45) and social dysfunction did not have a statistically significant association with VI in the final linear regression model and did not remain in the model. Total GHQ score had a statistically significant association with VI (ß = 1.02; 95% CI 0.39 to 1.64) in the presence of covariates. Regarding the association between VI and GHQ components, the physical symptoms had the highest R2 (R2 = 0.159). Patients with VI suffer more from anxiety, depression, and physical symptoms regardless of age, sex, education, and other effective variables. The coincidence of aging with VI and the association of VI with mental disorders emphasizes the importance of a broader view of the elderly and the aging process.

The association between ocular biometric components and corneal aberrations.

CLINICAL RELEVANCE: Evaluating factors affecting corneal higher-order aberration component has a very important role in interpreting the characteristics of the formed image on the retina. BACKGROUND: To determine the relationship between ocular biometric components and corneal higher-order aberrations in an elderly population. METHODS: This report is related to a subsample of the Tehran Geriatric Eye study (TGES), a population-based cross-sectional study that was conducted on individuals aged 60 years and above in Tehran city, Iran using multistage stratified random cluster sampling. All study participants underwent ocular examinations including visual acuity measurement, refraction and slit-lamp biomicroscopy. Anterior segment imaging and corneal aberrometry were performed using Pentacam AXL. RESULTS: In the present study, 644 eyes of 415 individuals (56.9% female) with mean age of 66.36 ± 4.70 years were evaluated. According to a multiple generalised estimating equation model, the root mean square of total higher-order aberrations was related to age (ß = 0.081, p = 0.002), crystalline lens thickness (ß = 0.08, p < 0.001), and corneal diameter (ß = -0.04, p = 0.014). The root mean square of total coma aberration was directly related to the female sex (ß = 0.02, p = 0.05), and crystalline lens thickness (ß = 0.06, p < 0.001). There was a direct relationship between the root mean square of third- and fourth-order higher-order aberrations and crystalline lens thickness (p < 0.001). Spherical aberration was directly related to the male sex (ß = -0.02, p = 0.004), axial length (ß = 0.05, p < 0.001) and central corneal thickness (ß = 0.001, p = 0.025), and was inversely related to anterior chamber depth (ß = -0.07, p = 0.031) and crystalline lens thickness (ß = -0.25, p < 0.001). CONCLUSION: Ocular biometric components are related to corneal aberrations in the elderly. These factors need to be considered in respect of medical and surgical procedures required for the elderly.

The prevalence of red-green color vision deficiency and its related factors in an elderly population above 60 years of age.

AIM: To determine the prevalence of red-green (RG) color vision deficiency (CVD) in an elderly population and its related factors. METHODS: This report is a part of the Tehran Geriatric Eye Study: a cross-sectional population-based study that was conducted on the elderly population (≥60y) of Tehran, Iran using multi-stage stratified random cluster sampling. All study participants underwent complete ocular examination, including the measurement of uncorrected and best-corrected visual acuity, objective and subjective refraction, and slit-lamp biomicroscopy. The color vision was tested using Ishihara plates with the near optical correction in place. RESULTS: Of the 3791 invitees, 3310 participated in the study. The data of 2164 individuals were analyzed after applying the exclusion criteria. The prevalence of R-G CVD was 3.73% (95%CI: 2.37%-5.09%) in the whole sample; the prevalence of protanomaly, protanopia, and deuteranopia was 1.51%, 1.76%, and 0.45%, respectively. The prevalence of R-G CVD was significantly higher in males than in females. The prevalence of RG CVD increased with advancing age from 2.91% in the age group 60-64y to 5.8% in the age group ≥80y (P=0.070). According to the multiple logistic regression model, male sex, and glaucoma were significantly related to RG CVD. Older age and hypertension also had a marginally significant relationship with RG CVD. CONCLUSION: Changes in color vision occur in the elderly due to the aging process and some physiological and pathological factors. Since the change in visual perception may affect the person's performance, this aspect of the visual system's function should also be taken into consideration in the examinations of the elderly.

Auto-refraction versus subjective refraction in different phakic and pseudophakic conditions: the Tehran Geriatric Eye Study (TGES).

AIM: To compare the subjective refraction data with non-cycloplegic auto-refraction findings in the geriatric population above 60 years of age according to the different crystalline lens conditions. METHODS: This report is a part of the Tehran Geriatric Eye Study (TGES) that was conducted from January 2019 to January 2020 on elderly population 60 years of age and above in Tehran. The samples were selected by multi-stage stratified random cluster sampling. Of 3791 individual invitees, 3310 (response rate: 87.3%) participated in this study. All study participants underwent non-cycloplegic auto-refraction (auto-refractometer/keratometer Nidek ARK-510) and subjective refraction. RESULTS: Regarding the sphere, eyes with mixed cataract had the worst limits of agreement (LoA: -1.24 to 0.87) and the best agreement was related to the pseudophakic eyes (LoA: -0.83 to 0.54). The highest (0.27±0.31 D) and lowest (0.21±0.27 D) differences between the two methods regarding the cylinder power were observed in eyes with cortical cataract and normal eyes, respectively. The worst LoA between the two methods in measuring the cylinder power was related to the eyes with mixed cataract (LoA: -0.44 to 0.96). Regarding the J0 (horizontal/vertical components of astigmatism), the mean values of J0 obtained by auto-refraction were tended more toward against the rule direction in all crystalline lens conditions, and the two methods had the greatest difference in cortical cataract cases (0.05±0.17 D). Regarding the J45 (oblique components of astigmatism), the lowest (0±0.11 D) and highest (-0.01±0.12 D) differences were observed in normal eyes and eyes with cortical cataract, respectively. CONCLUSION: The auto-refractometer/keratometer Nidek ARK-510 results in the elderly with different phakic and pseudophakic conditions do not correspond well with subjective refraction findings. This discrepancy in spherical findings is more pronounced in individuals with mixed cataract than in other cases.

Residual refractive errors in pseudophakic eyes and related factors: a population-based study.

AIM: To determine residual refractive error after cataract surgery in pseudophakic eyes and its relationship with age, sex, and axial length (AL). METHODS: In this population-based cross-sectional study, the sampling was performed on individuals aged 60y and above in Tehran, Iran using a multi-stage stratified random cluster sampling method. Pseudophakic eyes with a best-corrected visual acuity of 20/32 or better were analyzed and their refractive results were reported. RESULTS: The mean spherical equivalent (SE) refraction was -0.34±0.97 diopters (D) and the mean absolute SE was 0.72±0.74 D with a median of 0.5 D. Moreover, 32.68% (n=546, 95%CI: 30.27%-35.08%), 53.67% (n=900, 95%CI: 51.23%-56.1%), 68.99% (n=1157, 95%CI: 66.96%-71.02%), and 79.73% (n=1337, 95%CI: 77.69%-81.76%) of the eyes had a residual SE within ±0.25, ±0.50, ±0.75, and ±1.00 D of emmetropia, respectively. According to the multiple logistic regression model, increasing age was associated with a statistically significant decrease in predictability for all cut points. Moreover, the predictability based on all cut points was significantly lower in individuals with an AL longer than 24.5 mm than in those with an AL between 22 to 24.5 mm. CONCLUSION: Based on the results, the accuracy of intraocular lens (IOL) power calculation is lower for those who underwent cataract surgery during the last 5y in Tehran, Iran. Among the most important influential factors, the choice of IOL or it's power disproportionate to eye conditions and age can be mentioned.

Three-year change in corneal asphericity in children at the age of emmetropisation.

PURPOSE: To determine the 3-year changes in anterior and posterior values of corneal asphericity (Q) in 6- to 12-year-old children. METHODS: The first and second phases of the study were conducted in 2015 and 2018, respectively. The target population in the first phase was 6- to 12-year-old students in Shahroud, Iran. Multistage cluster sampling was performed on urban students. Additionally, all rural students in Shahroud county were invited to participate. Corneal imaging and ocular biometry were performed using the Pentacam-HR and Allegro Biograph, respectively. RESULTS: A total of 4961 right eyes were analysed in this report. The mean (95% confidence interval) anterior and posterior Q values for an 8-mm chord diameter were -0.38 ± 0.11 (-0.39 to -0.38) and -0.32 ± 0.12 (-0.33 to -0.32) in the first phase of the study, respectively. The mean 3-year changes in anterior and posterior Q values were 0.00 ± 0.08 (95% CI: 0.00-0.00) and -0.01 ± 0.06 (95% CI: -0.01 to -0.01), respectively. Based on a multiple regression model, advancing age (ß = -0.002; [-0.003 to -0.001]), 3-year increase in mean keratometry (ß = -0.04; [-0.06 to -0.02]), central corneal thickness (ß = -0.001; [-0.001 to -0.000]), lens thickness (-0.05; [-0.11 to -0.003]) and anterior chamber depth (-0.09; [-0.15 to -0.03]) showed a statistically significant association with increased anterior Q prolation. Increased axial length was associated with a decrease in Q (ß = 0.02; [0.004 to 0.03]). In addition, female gender (ß = -0.004; [-0.007 to -0.001]) was significantly associated with a more prolate posterior Q value, while rural residence (ß = 0.005; [0.002 to 0.009]) was significantly associated with a more oblate posterior Q value. CONCLUSION: Three-year changes in anterior and posterior Q values were very small. The cornea tends to become more prolate with increasing age.

Anisometropia Profile in Elderly Population: Tehran Geriatric Eye Study.

PURPOSE: To investigate the distribution and prevalence of anisometropia according to age, gender and ocular biometry in a geriatric population in Tehran, Iran. METHODS: The present study was conducted on the geriatric population aged above 60 years. The study participants were selected using stratified random cluster sampling. The uncorrected and best-corrected visual acuity, dry objective (ARK510A, Nidek Co. 42 LTD, Aichi, Japan) and subjective refraction and ocular biometry (IOL Master 500; Carl Zeiss Meditec, Jena, Germany) were recorded for each patient. The magnitude and prevalence of anisometropia were evaluated in association with influential factors in cut-points of 0.50, 1.00, 1.50 and 2.00 diopter (D). RESULTS: The mean age of participants (3237 individuals, 54% were female) was 68.19 ± 6.48 (range: 60-97) years. The mean anisometropia in the whole sample was 0.82 D (95% CI: 0.76 - 0.88 D), which increased from 0.62 D (in those aged 60-64 years old) to 1.36 D (in those above 80 years). The prevalence of anisometropia >1 D in total population, males, and females were 23.81%, 24.9%, and 22.76%, respectively. The odds ratio of anisometropia was higher in cases with cataracts, myopia compared to emmetropia, keratometry asymmetry, axial length asymmetry (P = .001), and corneal diameter asymmetry (all others, P < .001). CONCLUSION: The results of the present study show a high prevalence of anisometropia in elderly population, which was related to refractive error, cataract, age, gender, and ocular biometry asymmetry.

Assessing Accuracy of Okulix Ray-Tracing Software in Calculating Intraocular Lens Power in the Long Cataractous Eyes.

Purpose: To investigate the accuracy of Okulix ray-tracing software in calculating intraocular lens (IOL) power in the long cataractous eyes and comparing the results with those obtained from Kane, Holladay 1 with optimized constant, SRK/T with optimized constant, Haigis with optimized constant, and Barret Universal 2 formulas. Methods: The present study evaluates the refractive results of cataract surgery in 85 eyes with axial length > 25 mm and no history of ocular surgery and corneal pathology. IOL power calculation was performed using the Okulix software. The performances of Okulix software in comparison with the five other formulas were evaluated by predicted error, mean absolute error, and mean numerical error 6 months after surgery. Results: The mean calculated IOL power by the Okulix software was +13.48 ± 4.19 diopter (D). The mean of the 6-month postoperative sphere and spherical equivalent were +0.18 ± 0.63 and -0.34 ± 0.78 D, respectively. Also, the 6-month spherical equivalent in 56.6% and 80% of eyes were within ±0.05 and ±1.00 D, respectively. The predicted error (P < 0.001) and the mean numerical error (P < 0.001) were different between the six studied methods; however, we were not able to find any significant differences in the mean absolute error among six studied methods (P: 0.211). Conclusion: The present study showed acceptable performance of the Okulix software in IOL power calculation in long eyes in comparison with the other five methods based on the postoperative refractive error, calculated mean absolute error, and mean numerical error.

Effects of N-acetylcysteine supplementation on disease activity, oxidative stress, and inflammatory and metabolic parameters in rheumatoid arthritis patients: a randomized double-blind placebo-controlled trial.

Considering the importance of inflammation and oxidative stress in the development of rheumatoid arthritis (RA) as well as anti-inflammatory and antioxidant features of N-acetylcysteine (NAC), this study was conducted to evaluate the effect of NAC supplementation on disease activity, oxidative stress, and inflammatory and metabolic parameters in RA patients. In a randomized double-masked placebo-controlled trial, 74 RA subjects were chosen and randomly divided into two groups to take 600 mg of NAC or placebo twice daily for 3 months. Before and after the study, disease activity was assessed via disease activity score-28 (DAS-28), and serum malondialdehyde (MDA), total antioxidant capacity (TAC), glutathione peroxidase (GPX) activity, nitric oxide (NO), high-sensitivity C-reactive protein (hs-CRP), fasting blood sugar (FBS), lipid profile, and erythrocyte sedimentation rate (ESR) were measured. Seventy patients completed the trial. Compared to baseline, NAC significantly reduced morning stiffness (P < 0.001), DAS-28 (P < 0.001), ESR (P = 0.004), MDA (P < 0.001), NO (P < 0.001), hs-CRP (P = 0.006), FBS (P < 0.001), and low-density lipoprotein cholesterol (LDL-C) (P = 0.023) and significantly increased GPx activity (P = 0.015) and high-density lipoprotein cholesterol (HDL-C) level (P = 0.001). After treatment, remarkable differences were only seen between the two groups in serum NO (P = 0.003), FBS (P = 0.010), and HDL-C (P < 0.001) adjusted for baseline measures. There were no significant changes in morning stiffness, DAS-28, ESR, hs-CRP, MDA, TAC, GPx activity, triglyceride, total cholesterol, and LDL-C levels compared to the placebo group. In conclusion, NAC did not improve RA disease activity, but reduced NO and FBS and increased HDL-C levels. It appears that NAC should not be consumed as a replacement for routine medications prescribed in RA therapy, but it can be used as an adjunctive therapy.

Vector analysis of moderate to high myopic astigmatism after small-incision lenticule extraction (SMILE): 12-month follow-up.

PURPOSE: To evaluate the refractive outcomes of small-incision lenticule extraction (SMILE) surgery in moderate to high myopic astigmatism. STUDY DESIGN: Prospective interventional case series. METHODS: This study evaluated 111 eyes of 68 patients treated with femtosecond SMILE surgery for the correction of myopia and astigmatism. Inclusion criteria were myopia of - 0.5 D or more and astigmatism between - 1.0 D and -5.0 D. Refractive and visual measurements were obtained preoperatively, 1 and 12 month(s) postoperatively. Vector analysis was used to study the astigmatic outcomes at 12-month follow-up. Comparison of results in two groups of patients with astigmatism below and over 3.00 D was performed. RESULTS: The preoperative mean spherical equivalent was -5.48 ± 2.17 D (range - 1.75 to - 10.00 D) and the mean cylinder was -2.02 ± 1.09 D (range - 1.00 to - 5.00 D). The mean postoperative cylinder value was -0.60 ± 0.52 D at 12-month visit. The 12-month safety and efficacy indices were 0.98 ± 0.07 and 0.97 ± 0.12, respectively. The high astigmatism group showed significantly lower safety and efficacy indices. The postoperative residual astigmatism was 0.5 D or less in 73% of the eyes. Higher amount of residual astigmatism was observed in the high astigmatism group. The angle of error was ± 5 degrees in 49% and ± 15 degrees in 87% of the eyes. CONCLUSION: SMILE surgery is effective and safe method for correcting myopic astigmatism. Vector analysis indicated a tendency for the under correction of astigmatism in subjects with high astigmatism.

Clinical Outcomes of a New Type of Continuous Intrastromal Corneal Ring for Treatment of Keratoconus.

PURPOSE: The purpose of this study was to evaluate the efficacy and safety of implantation of a new continuous corneal ring in keratoconic corneas of an Iranian population. METHODS: This study was conducted on 95 contact lens-intolerant keratoconic eyes with clear central corneas. A continuous corneal ring, annular intrastromal corneal inlay (AICI), was inserted using femtosecond laser in all cases. Patients were followed up for 1, 3, and 12 months postsurgery. Visual and subjective refractive outcomes were evaluated in each examination. Besides, keratometry and aberrometric values were recorded before and 12 months after surgery. Finally, vector analysis of refractive astigmatism was performed using the Alpins method. RESULTS: The uncorrected and corrected distance visual acuities improved significantly 12 months after surgery from 0.91 ± 0.39 to 0.38 ± 0.22 (P < 0 0.001) and 0.33 ± 0.21 to 0.13 ± 0.11 logMAR (P < 0.001), respectively. Moreover, spherical and cylindrical refractive components reduced from -2.52 ± 2.62 to -0.76 ± 1.78 D (P < 0.001) and -4.14 ± 1.64 to -1.91 ± 1.18 D (P < 0.001), respectively. The mean anterior keratometry had a significant reduction 12 months after AICI insertion (P< 0.001). Primary coma and spherical aberration values showed a significant increase (both, P < 0.05). Our results showed 100% safety (safety index: 1.8) and 45% efficacy (efficacy index: 1). CONCLUSIONS: AICI implantation seemed to be a safe and effective procedure for improving visual acuity and refractive outcomes in subjects with keratoconus.

Dynamic and Static Pupil Changes After Near Work: Comparison Between Reading a Book and Using a Smartphone.

Objectives: Decreased static pupil size due to accommodation is a common clinical finding; however, changes in pupillary dynamic responses after near-work activities such as reading a book and using a smartphone are not well understood. Methods: The present study was performed on 76 right eyes of 76 volunteers (mean age: 20.95±2.34 years) who had ocular near activity more than 4 h per day. The participants were divided into two groups based on the dominant activity, reading a book (Group 1) or using a smartphone (Group 2). Evaluation of dynamic and static parameters of the pupil was performed before and after 1 h of continuous routine eye activity in both groups and compared. Results: Near work reduced pupil diameter (PD) in all static components (p<0.001) and the amount of change in the min PD (p=0.039) and mesopic PD (p=0.043) were different between two groups and were higher in Group 1 (both, p<0.05). Dynamic elements showed a decrease in initial diameter, amplitude and velocity of contraction and dilation, and an increase in other components so that the changes after using smartphone were significant in all dynamic parameters (all, p<0.05), but reading the book only made a significant difference in the initial diameter, amplitude, and velocity of contraction and duration of dilation (all, p<0.05); the changes were only different in the initial diameter between the two studied groups, which was higher in Group 1 (p=0.047). Conclusion: The present study showed that reading a book and using smartphone cause changes in the pupil components, which were decreasing in diameter components and velocity of changes and increasing in latency of changes; the type of ocular work may affect the changes.

Changes in the Optical Corneal Densitometry, Visual Acuity, and Refractive Error after the Annular Intracorneal Inlay Implantation.

PURPOSE: To investigate the changes in the optical corneal densitometry as an objective method in assessing the corneal light back-scattering before and 1 year after the annular intracorneal inlay (AICI) implantation into the keratoconic corneas. METHODS: Changes in the optical corneal densitometry, visual acuity, refractive, and tomographical status were assessed before and 1 year after the AICI implantation into the corneas with different stages of keratoconus. Optical corneal densitometry was evaluated using the Pentacam-HR in 0-2, 2-6, 6-10, and 10-12 mm rings in the anterior 120 µ, central layers, posterior 60 µ and also the total value were measured for cornea in the Grey Scale Unit criterion. RESULTS: Totally, 34 patients with keratoconus were studied; the uncorrected and best corrected visual acuity were increased after the surgery (0.98 ± 0.25 to 0.53 ± 0.30 logMAR, P < 0.001 and 0.26 ± 0.18 to 0.19 ± 0.14, P = 0.007 logMAR, respectively); the spherical equivalent was decreased from -4.45 ± 2.25 to - 2.06 ± 2.01 D (P = 0.004). AICI implantation led to an increase in the amount of optical corneal densitometry in 0-2 mm central, 2-6 mm central, 6-10 mm central, total central, 2-6 mm posterior, and 2-6 mm total rings (all, P < 0.05); however, a decrease was observed in 0-2 mm anterior ring (P = 0.049). Results of statistical analysis showed that the total optical corneal densitometry, anterior total, and posterior total back-scattering did not change after the AICI implantation (all, P > 0.05). CONCLUSIONS: Our results revealed a significant improvement in the visual function, including refractive error and visual acuity following the AICI implantation. Changes in the optical corneal densitometry were different in distinct regions and layers however, the total amount did not change after the AICI implantation.

The distribution of the near point of convergence and its related factors in an elderly population: the Tehran Geriatric Eye Study (TGES).

BACKGROUND: To determine the distribution of the near point of convergence (NPC) and its related factors in an elderly population in Tehran, Iran. METHODS: This population-based cross-sectional study was conducted on the elderly population (60 years of age and over) of Tehran, Iran in 2019. The samples were selected using stratified random cluster sampling. The examinations included the measurement of uncorrected and best-corrected visual acuity, objective and subjective refraction, unilateral and alternate cover test, ocular health examination, and NPC measurement. RESULTS: The mean age of the participants was 65.90 ± 4.56 years and 59.6% of them were females. The mean (95% CI) NPC in the total sample was 7.84 cm (95% CI: 7.65-8.03). The mean (95% CI) NPC in males and females was 7.92 cm (7.63-8.21) and 7.75 cm (7.54-7.97) (P = 0.338), respectively. The mean NPC increased from 7.8 cm (95% CI: 7.55-8.05) in the age group 60-64 years to 8.83 cm (95% CI: 7.47-10.2) in the age group ≥ 80 years (P > 0.05). The mean (95% CI) NPC in emmetropic, myopic, and hyperopic individuals was 7.67 cm (95% CI: 7.33-8.02), 7.96 cm (7.56-8.37), and 7.87 cm (7.63-8.11), respectively (P = 0.378). There was no statistically significant relationship between NPC with education level, smoking, diabetes mellitus (DM), and hypertension (HT). CONCLUSIONS: The NPC values found in this study were significantly lower (less remote) than the values reported in previous studies in similar age groups. The NPC had no significant relationship with age, sex, education level, smoking, DM, and HT.

Ocular biometry characteristics in cataract surgery candidates: a cross-sectional study.

Background: This study was conducted to investigate ocular biometry parameters in cataract surgery candidates in northern Tehran, Iran using OA-2000 biometry device. Methods: In this cross-sectional study, values of ocular biometry parameters, including axial length (AL), anterior chamber depth (ACD), mean corneal curvature (mean K), lens thickness (LT), corneal astigmatism (CA), and white-to-white (WTW) of 818 eyes with cataracts, were measured using the OA-2000 biometry device (Tomey, Nagoya, Japan). The participants were divided into si age subgroups, in 10-year intervals. Finally, the values of the biometry parameters were calculated, and the trend of changes was examined for both age and sex subgroups. Results: The mean (standard deviation [SD]) of age of the participants was 63.82 (13.25) years. Mean (SD) of biometry parameters were as follows: AL, 23.36 (1.55) mm; ACD, 3.09 (0.40) mm; LT, 4.45 (0.55) mm; mean K, 44.51 (1.72) D; CA, 1.06 (0.94) D; and WTW, 11.81 (0.45) mm. Most of the parameters showed significant age-related changes in the total population. There was an increase in LT (P < 0.001) and mean K (P = 0.001), as well as a decrease in AL (P < 0.001) and ACD (P < 0.001) with age. Moreover, AL had a negative negligible correlation with LT (r = - 0.24; P < 0.001) and mean K (r = - 026; P < 0.001), as well as a weak positive correlation with ACD (r = + 0.44; P < 0.001). Conclusions: Our study revealed that the mean values of most biometric parameters varied across age and sex subgroups. Moreover, most of the parameters showed significant age-related changes in the total population.

Corneal biomechanical outcome of collagen cross-linking in keratoconic patients evaluated by Corvis ST.

PURPOSE: A 6-month evaluation of the topographic and biomechanical changes induced by corneal collagen cross-linking (CXL) in keratoconic eyes using Pentacam and Corvis ST. DESIGN: Longitudinal prospective case series. METHODS: In this study, 67 eyes of 67 patients with progressive keratoconus (KCN) treated with "Epithelium-off" CXL were evaluated. Patients with stages 1 or 2 of KCN and a corneal thickness of at least 400 µm at the thinnest point were included. Standard ophthalmologic examinations were carried out for all patients. The topographic and biomechanical measurements of the cornea were obtained by Pentacam (Oculus Optikgeräte GmbH, Wetzlar, Germany) and Corvis ST (Oculus Optikgeräte GmbH, Wetzlar, Germany) preoperatively and 6-month postoperatively. RESULTS: The mean age of the participants was 21.68 ± 4.23 years. There was significant difference in mean spherical equivalent (SE) before and 6 months after CXL. Uncorrected and best corrected visual acuity improved postoperatively, although not statistically significant. The mean and maximum keratometry showed a significant decrease 6 months after CXL (0.93 ± 0.38 D and 1.43 ± 0.62 D, respectively p < 0.001). Among Corvis ST parameters, first applanation length and velocity (AL1 and AV1) showed statistically significant changes. The radius at highest concavity changed significantly (0.13 ± 0.37 mm mean increase after CXL; p < 0.001). A significant increase was observed in stiffness parameter A1 (SP-A1; p < 0.001) and significant decreases were noted in integrated radius (IR) and deformation amplitude ratio (DAR; p < 0.001). CONCLUSION: Analyzing biomechanical changes after corneal cross-linking can provide basis for efficient KCN treatment. Corvis ST parameters demonstrated changes in corneal biomechanical characteristics indicative of stiffing after CXL.

A systematized review of cognitive load theory in health sciences education and a perspective from cognitive neuroscience.

INTRODUCTION: To design instructions in health sciences education, it is highly relevant to heed the working memory and the approaches for managing cognitive load. In this article, we tried to mention the implications of cognitive load theory (CLT) for optimizing teaching-learning in health sciences education and discussing cognitive load from the perspective of cognitive neurosciences as brain-aware medical education. MATERIALS AND METHODS: We searched databases of Pubmed, Proquest, SCOPUS, and ISI Web of Science for relevant literature in September 1, 2018. RESULTS: The 27 articles out of a total of 46 records, along with 23 papers from snowballing and hand searching were included in this study. Main items encompassed; "Various types of cognitive loads," "Aim of cognitive load theory," "Strategies to managing Cognitive Load," "Cognitive Load Theory in novice and experienced learners and "expertise reversal effect," Medical and Health Sciences Curriculums and Cognitive Load Theory," "Challenges of Cognitive Load Theory." CONCLUSIONS: We discussed six important themes for CLT in health sciences education according to the literature. Mental imagery (visualization) as one of the useful techniques to optimize germane load was suggested, as it processes further gain access to neural circuits that are engaged in sensory, motor, executive, and decision-making pathways in the brain.

Corneal Biomechanical Properties in Varying Severities of Myopia.

Purpose: To investigate corneal biomechanical response parameters in varying degrees of myopia and their correlation with corneal geometrical parameters and axial length. Methods: In this prospective cross-sectional study, 172 eyes of 172 subjects, the severity degree of myopia was categorized into mild, moderate, severe, and extreme myopia. Cycloplegic refraction, corneal tomography using Pentacam HR, corneal biomechanical assessment using Corvis ST and Ocular Response Analyser (ORA), and ocular biometry using IOLMaster 700 were performed for all subjects. A general linear model was used to compare biomechanical parameters in various degrees of myopia, while central corneal thickness (CCT) and biomechanically corrected intraocular pressure (bIOP) were considered as covariates. Multiple linear regression was used to investigate the relationship between corneal biomechanical parameters with spherical equivalent (SE), axial length (AXL), bIOP, mean keratometry (Mean KR), and CCT. Results: Corneal biomechanical parameters assessed by Corvis ST that showed significant differences among the groups were second applanation length (AL2, p = 0.035), highest concavity radius (HCR, p < 0.001), deformation amplitude (DA, p < 0.001), peak distance (PD, p = 0.022), integrated inverse radius (IR, p < 0.001) and DA ratio (DAR, p = 0.004), while there were no significant differences in the means of pressure-derived parameters of ORA between groups. Multiple regression analysis showed all parameters of Corvis ST have significant relationships with level of myopia (SE, AXL, Mean KR), except AL1 and AL2. Significant biomechanical parameters showed progressive reduction in corneal stiffness with increasing myopia (either with greater negative SE or greater AXL), independent of IOP and CCT. Also, corneal hysteresis (CH) or ability to dissipate energy from the ORA decreased with increasing level of myopia. Conclusions: Dynamic corneal response assessed by Corvis ST shows evidence of biomechanical changes consistent with decreasing stiffness with increasing levels of myopia in multiple parameters. The strongest correlations were with highest concavity parameters where the sclera influence is maximal.