Subfoveal choroidal thickness in a general elderly population; Tehran geriatric eye study.

PURPOSE: To determine the distribution of subfoveal choroidal thickness (SFCT) and its associated demographic, ocular, and systemic factors in an elderly population. METHODS: This report is part of the Tehran Geriatric Eye Study (TGES); a population-based cross-sectional study that was conducted on the urban elderly population of Tehran, aged 60 years and above using multi-stage stratified random cluster sampling. Choroidal imaging was performed using Spectralis SD-OCT with enhanced depth imaging mode. RESULTS: The average SFCT was 265.3 ± 25.9 µm (95% CI: 262.8-267.7) in the whole sample. According to the multiple generalized estimating equation (GEE) model, pseudophakia had a statistically significant direct relationship with SFCT (coefficient = 5.69), and history of cerebrovascular accident (CVA) was significantly inversely related to SFCT (coefficient=-4.77). Moreover, there was a significant interaction between age and sex in the average SFCT so that with increasing age, the SFCT increased in men and decreased in women. CONCLUSION: The normal values of SFCT in the present study can be used as a reference database for clinical and research purposes. Age-sex interaction, pseudophakia, and history of CVA were significantly associated with SFCT in the elderly population. It is recommended that these factors be taken into account when interpreting SFCT data.

Analysis of macular thickness and peripapillary retinal nerve fiber layer thickness in various ABO and Rh blood groups.

PURPOSE: To determine the association between ABO and Rh blood groups with retinal structural indices including macular thickness and peripapillary retinal nerve fiber layer (RNFL) thickness. METHODS: This cross-sectional study was conducted using convenience sampling in a tertiary referral eye hospital in Tehran, Iran. Study participants were referred to the hospital laboratory to test their blood group. Ocular examinations were performed including measurement of visual acuity, auto-refraction, subjective refraction, and slit-lamp biomicroscopy. Retinal imaging was carried out using Spectral-domain OCT under dilated papillary conditions. RESULTS: Three hundred and twenty-eight individuals were recruited in this study. Of these, 219 (60.7%) were female and the mean age of the participants was 63.29 ± 5.57 years (range: 56 to 83 years). According to the multiple linear regression model, the global peripapillary RNFL thickness [coefficient: -3.05 (95% CI: -5.30 to -0.74); P = 0.010] and peripapillary RNFL thickness in the superior [coefficient: -4.65 (95% CI: -8.40 to -0.89), P < 0.001] and inferior [coefficient: -4.00 (95% CI: -7.81 to -0.19); P = 0.040] quadrants were significantly thinner in individuals with blood type B compared to those with other ABO blood groups. The average [coefficient: 12.69 (95% CI: 4.12-21.64); P = 0.004) and central [coefficient: 16.21 (95%: 6.44-25.97); P = 0.001) macular thicknesses were significantly thicker in AB group compared to other blood groups. The average macular thickness was significantly thinner in Rh + compared to the Rh- group [coefficient: -8.33 (95% CI: -15.4 to -1.25); P = 0.021]. CONCLUSION: Retinal structural indices may be related to blood groups implying a genetic linkage. Considering the lack of consistency among various studies, larger trials are needed to explore the effect of ABO and Rh grouping on peripapillary RNFL and macular thicknesses.

Vision-related symptoms, accommodative and binocular vision performance in young diabetics vs. normal controls.

PURPOSE: To compare accommodative and binocular vision performance between young diabetic subjects and normal controls, and to investigate the correlation of accommodative/binocular indices with the severity of diabetes. METHODS: Thirty young subjects with diabetes mellitus (DM) and 30 age-matched normal controls were recruited in this hospital-based cross-sectional study. DM was diagnosed by a haemoglobin A1c (HbA1c) higher than 6.5%. The status of vision-related symptoms was examined by the convergence insufficiency symptoms survey (CISS). All participants underwent a complete optometric examination including visual acuity measurement, objective and subjective refraction, accommodative and binocular vision assessments. RESULTS: All study participants were between 18 and 40 years of age. There were no statistically significant differences in best-corrected visual acuity (BCVA), sphere, cylinder and spherical equivalent refraction (SE) between the diabetes and control groups. The median near point of convergence (NPC) was significantly more remote in diabetics compared with the control group. Mean accommodative amplitude (AA) and vergence facility (VF) and the median monocular accommodative facility (AF) were significantly lower in diabetic subjects compared with normal controls. In addition, the median accommodative lag in the diabetic group was significantly higher than the control group. A significantly higher percentage of the diabetic group were symptomatic (26.6%), compared with the controls (6.6%). The NPC and accommodative lag showed a significant positive correlation with the HbA1c level, while VF, AA and AF exhibited a significant negative correlation with HbA1c. CONCLUSION: Aspects of accommodative and binocular vision performance are strongly affected by DM. There is also a significant correlation between accommodative and binocular disorders with the severity of DM. A significant percentage of young subjects with DM have severe vision-related symptoms.

Convergence Insufficiency in the Geriatric Population.

SIGNIFICANCE: The present study is the first population-based study to examine the prevalence of convergence insufficiency and its associations specifically in the geriatric population. Knowledge of the population-based determination of prevalence of this disorder in the elderly is necessary to support proper clinical diagnosis and management. PURPOSE: This study aimed to determine the prevalence of convergence insufficiency and its associated factors in a geriatric population. METHODS: In this study, all residents older than 60 years in Tehran city were selected through random stratified cluster sampling. All participants underwent a complete ocular examination including the measurement of uncorrected and best-corrected visual acuity, objective and subjective refraction, binocular vision assessments including unilateral and alternating cover tests, measurement of the near point of convergence, the positive fusional vergence, and finally ocular health examination. RESULTS: In this population-based sample of 1793 participants, the overall prevalences of two-sign and three-sign convergence insufficiency were 29.6% (95% confidence interval, 27.2 to 32.0%) and 21.5% (95% confidence interval, 19.5 to 23.6%), respectively. There were no statistically significant differences in the prevalence of both two-sign (P = .19) and three-sign (P = .41) convergence insufficiency between men and women. The highest and lowest prevalences of two-sign and three-sign convergence insufficiency were in the age groups 70 to 74 and 75 to 79 years, respectively. The prevalence showed no significant trend with age (P = .26 for two-sign convergence insufficiency, P = .33 for three-sign convergence insufficiency). In the multiple logistic regression model, none of the variables, including age, sex, and refractive errors, showed a significant relationship with convergence insufficiency (all, P > .05). CONCLUSIONS: The results of the present study showed a high prevalence of convergence insufficiency in the geriatric population. Clinicians should give special attention to this binocular vision disorder in this age group.

Agreement of Fixation Disparity Curve between Two Different Instruments.

SIGNIFICANCE: Fixation disparity tests with various characteristics of fusional stimulus are very important for assessment of decompensated heterophoria. The results suggest that there was no reasonable agreement between the fixation disparity curve's parameters of the modified near Mallett unit and the Sheedy disparometer. PURPOSE: The purpose of this study was to determine the agreement of the fixation disparity curve parameters between the modified near Mallett unit and the Sheedy disparometer in patients with decompensated near heterophoria. METHODS: A total of 147 young adults (mean age, 22.7 ± 4.8 years) participated in this cross-sectional study. After applying the exclusion criteria, the statistical analysis was done on the data of 134 individuals. All participants underwent preliminary optometric examinations including the measurement of uncorrected and best-corrected visual acuity, objective and subjective refraction, and unilateral and alternating cover tests. The fixation disparity was evaluated using the modified near Mallett unit and the Sheedy disparometer at 40 cm, and forced-vergence fixation disparity curves were generated. RESULTS: There were statistically significant differences in the fixation disparity curve parameters (except the center of symmetry) between the two devices. The median fixation disparity measured by the Sheedy disparometer was more positive compared with the modified near Mallett unit (toward more esodisparity or less exodisparity). The median associated phoria measured by the Sheedy disparometer was more positive compared with the Mallett unit. Also, the slope of the curve obtained by the Mallett unit was steeper. The wide limits of agreement indicated the poor agreement of all fixation disparity curve parameters between the two instruments.

Corneal asphericity and related factors in the geriatric population: A population-based study.

PURPOSE: To determine the distribution of the corneal asphericity coefficient (Q value) and related factors in an Iranian geriatric population. METHODS: This population-based study was conducted in 2019 in Tehran, using stratified multistage random cluster sampling. The study population was ≥60 years of age. Participants underwent corneal imaging using a Pentacam HR. Mean keratometry, corneal astigmatism, central corneal thickness, anterior chamber depth and the overall anterior and posterior Q values (for 8 mm chord diameter) were recorded. Axial length measurements were performed using the IOL Master 500. RESULTS: 2457 eyes of 2457 individuals were analysed. The mean age was 67.3 ± 5.82 years and 1479 (60.2%) were female. The mean Q value for the anterior corneal surface was -0.35 ± 0.17 (95% CI: -0.35 to -0.34). The anterior Q value showed a statistically significant inverse relationship with axial length and mean keratometry, and a significant direct association with anterior chamber depth and corneal astigmatism. The mean posterior Q value was -0.41 ± 0.15 (95% CI: -0.42 to -0.40). The posterior Q value had a significant direct relationship with age, anterior chamber depth, mean keratometry and corneal astigmatism. CONCLUSION: The corneal Q values in this geriatric Iranian population were more negative than the values reported in most previous studies. Corneal asphericity was greater affected by ocular biometry and corneal curvature than demographic factors and refractive status.

Comparison of Corneal Higher-order Aberrations between Miniscleral and Hybrid Lenses in Keratoconus.

SIGNIFICANCE: Fitting specialty contact lenses (hybrid and miniscleral) can be a useful option in keratoconus patients to decrease higher-order aberrations (HOAs) and increase the quality of vision. PURPOSE: The aim of the present study was to compare corneal HOAs between miniscleral and hybrid lenses in keratoconus patients. METHODS: The target population of this study was 37 patients with bilateral keratoconus aged 20 to 35 years who were referred to a specialized contact lens clinic by a corneal specialist. Pre-fitting examinations included objective and subjective refraction, measurement of uncorrected and best spectacle-corrected visual acuity, and measurement of corneal HOAs. Lens fitting was performed in the next step. Finally, post-fitting measurements including contact lens-corrected visual acuity and corneal HOAs were performed. RESULTS: The root mean square of the total HOAs significantly decreased after fitting both miniscleral and hybrid lens designs. There was a significant change in the third-order vertical coma and spherical aberration after fitting the miniscleral lens. In the hybrid lens group, a significant change was found only in vertical coma after fitting. There was no significant difference in the post-fitting HOA change between the two groups. CONCLUSIONS: The results of this study showed the effectiveness of both miniscleral and hybrid lenses in decreasing HOAs in keratoconus patients. No significant difference was observed between these two lenses in this regard.

The effect of base-in prism on vision-related symptoms and clinical characteristics of young adults with convergence insufficiency; a placebo-controlled randomised clinical trial.

PURPOSE: The aim of the present study was to evaluate the effect of base-in prism on symptoms and clinical characteristics of young adults with convergence insufficiency. METHODS: In this randomised clinical trial, 64 CI patients aged 18-38 years who presented to Bina Eye Hospital, Tehran, Iran between November 2018 and April 2019 were selected and randomly assigned to either prism or placebo groups. All participants underwent complete optometric examinations, including the measurement of visual acuity, objective and subjective refraction, and complete accommodative and binocular vision examinations. Clinical examinations were repeated after three months. The overall score of the Convergence Insufficiency Symptom Survey (CISS) was considered as the primary outcome measure. Secondary outcome measures included near exophoria, positive fusional vergence at near, near point of convergence, vergence facility, monocular accommodative facility, accommodative response, negative relative accommodation and accommodative convergence/accommodation (AC/A) ratio. RESULTS: The mean (S.D.) age of the participants was 25.5 (5.5) years and 44% of them were male. The mean CISS score was significantly lower in the prism group compared to the placebo group in the outcome examination (p < 0.001). Moreover, the values of monocular accommodative facility, accommodative response, and negative relative accommodation were significantly higher in the prism group versus the placebo group (p < 0.001). There was no significant difference in other parameters, including near positive fusional vergence, near point of convergence, vergence facility, and AC/A ratio between the two groups in the outcome examination (p > 0.10). CONCLUSION: The base-in prism reduced symptoms in young adults with convergence insufficiency, while it had no significant effect on the near point of convergence, near positive fusional vergence, vergence facility and AC/A ratio. However, the results of this study only supports the symptomatic effectiveness of prism in the short term and further studies are needed to assess the long-term effect of prism.

The Characteristics of Excimer Laser Refractive Surgery Candidates.

PURPOSE: To determine the demographic and refractive characteristics of excimer laser refractive surgery candidates in Iran. METHODS: This was a cross-sectional study between 2010 and 2014. All information was collected from 28 centers randomly selected from 12 provinces. Then, for each season of the year, one week was chosen through simple random selection, and within each week, 3 days were again chosen randomly. All excimer laser surgical procedures performed during these 3 days were identified by training staff, and data were extracted from patient charts. RESULTS: A total of 14,569 charts were reviewed; 67.5% of the subjects were female and the rest were male. Of the total surgeries, 18.6% had been done in 2010 which reached to 19.1% in 2014. The mean age of people receiving refractive surgery showed an upward trend (P<0.001) and female patients were significantly younger than male patients (P<0.001). The 25 to 39 years age group received the highest number of surgeries (31.9% of the total) and there was a significant association with gender (P<0.001). The most common refractive error was compound myopic astigmatism with a prevalence of 79.3%. In 2010, 33.3% of the performed surgeries were covered by insurance policies, and this decreased to 30.2% in 2014 (P<0.001). CONCLUSION: Women with compound myopic astigmatism in the age range of 25 and 35 years are the most frequent users of excimer laser refractive surgery. Less than one-third of laser refractive surgeries are covered by insurance policies. Therefore, proper planning for improving services to this group must be given priority.

Retinal nerve fibre layer thickness in a general population in Iran.

BACKGROUND: To determine retinal nerve fibre layer (RNFL) thickness distribution and its related factors in a general population of 45 to 69 year olds in Iran. DESIGN: Population-based cross-sectional study. PARTICIPANTS: Of the 5190 participants of phase one of Shahroud Eye Cohort Study, 4737 participated in Phase two (participation rate = 91.3%). METHODS: All study participants underwent visual acuity measurement, refraction tests, slit lamp examination and ophthalmoscopic fundus exam. Tests also included imaging with Cirrus HD-OCT 4000 and its RNFL thickness data were used in this study. MAIN OUTCOME MEASURES: The overall RNFL thickness and the average RNFL thickness in different quadrants. RESULTS: Mean RNFL thickness in the superior, inferior, nasal and temporal quadrants were 92.47 µm [95% confidence interval (CI): 92.14-92.80], 111.22 µm (95% CI: 110.7-111.73), 118.93 µm (95% CI: 118.31-119.55), 74.83 µm (95% CI: 74.07-75.59) and 65.48 µm (95% CI: 65.06-65.90). Multiple linear regression models indicated that RNFL thickness in all quadrants decreased with ageing, was lower in females (coefficient:-0.87 and P = 0.015), decreased by 1.42 µm (P < 0.001) for each millimetre increase in axial length and decreased by 0.41 µm (P = 0.041) for each diopter decrease in spherical equivalent refraction of myopia. CONCLUSION: RNFL thickness in the 45 to 69-year-old Iranian population is lower compared to other studies. This difference should be noted in making disease diagnoses, particularly glaucoma. Also, there is a significant relationship between ageing and RNFL thinning in all quadrants. Longer axial length, myopia and male gender are associated with reduced RNFL thickness.

Astigmatism in underserved rural areas: a population based study.

PURPOSE: Studying the prevalence of astigmatism and its related factors in underprivileged rural areas in Iran. METHODS: Using random cluster sampling, two rural areas in the north and southwest of Iran were randomly selected, and 3851 persons over 1 year of age were invited to the study. In addition to recording demographics, retinoscopic refraction was conducted using baseline auto-refraction results. The prevalence of astigmatism was determined based on cylinder error cut-off points of 0.50 dioptre (D), 1.00, 2.00 and 3.00 D. Multiple logistic regression was used to assess variables' relationship with astigmatism. RESULTS: The prevalence of astigmatism as a cylinder error greater than 0.50 D was 35.6% (95% CI: 33.7-37.6); this was 34.0% (95% CI: 31.4-36.6) in women and 36.9% (95% CI: 33.9-39.9) in men. The lowest prevalence was seen in the 6-20 year old age group (13.6%) and the highest prevalence was found in individuals older than 70 years (82.5%). In the multiple logistic regression model, age and education level were significantly related to astigmatism. The prevalence rates of with-the-rule (WTR), against-the-rule (ATR), and oblique astigmatism were respectively 15.0%, 17.2%, and 3.5%. The prevalence of WTR astigmatism decreased with age, while the prevalence of ATR (and oblique astigmatism to a lesser extent) increased. CONCLUSION: The prevalence of astigmatism was similar to previous studies; however, there were considerable age-related changes. In particular, the prevalence of astigmatism in elderly people was substantial and of concern, particularly given that virtually none of this age group were wearing distance spectacles.

Comparison of the accommodative amplitude measured with and without the use of a specialised accommodative rule in children.

OBJECTIVE: To determine the agreement between measurements of accommodative amplitude (AoA) in children using a specialised accommodative rule and measurments without it. METHODS: A total of 502 children underwent optometric examinations, including the measurement of visual acuity, objective and subjective refraction. AoA measurements were done with and without the Berens accommodative rule. The measurements of AoA were conducted monocularly using a -4 D lens. A fixation stick containing English letters equivalent to 20/30 visual acuity and a long millimetre ruler was used to measure AoA without the accommodative rule. This measurement was performed by the two trained examiners. The agreement between these methods was reported by 95% limits of agreement (LoA) and interclass correlation coefficient (ICC). RESULTS: The mean age of the participants was 11.7±1.3 years (range: 9-15 years) and 52.4% were male. The mean AoA with and without the accommodative rule was 20.02±6.02 D and 22.46±6.32 D, respectively. The 95% LoA between the two methods was -12.5 to 7.5 D, and the ICC was 0.67 (95% CI 0.63 to 0.70). The 95% LoA was narrower in higher age groups and males compared with females (18.92 vs 20.87). The 95% LoA was narrower in hyperopes (16.83 D) compared with emmetropes (18.37 D) and myopes (18.27 D). The agreement was not constant and decreased in higher values of AoA. CONCLUSION: There is a poor and non-constant agreement between the measurements of the AoA with and without the accommodative rule. The mean AoA was 2.5 D lower with using the accommodative rule.

Prevalence and Associated Factors of Pseudoexfoliation Syndrome in an Iranian Elderly Population: The Tehran Geriatric Eye Study.

PURPOSE: To investigate the prevalence and associated factors of pseudoexfoliation syndrome (PEX) in an Iranian elderly population. METHODS: This study, a population-based cross-sectional study conducted on individuals ≥60 years in Tehran, the capital of Iran in 2019 using a multi-stage stratified random cluster sampling. All study participants underwent complete ocular examination (including measurement of uncorrected and best-corrected visual acuity, refraction, slit-lamp biomicroscopy). The PEX was diagnosed based on the presence of white fluffy dandruff-like pseudoexfoliative material on the pupillary margin, on the anterior lens capsule, and/or the trabecular meshwork. RESULTS: Of the 3791 invitees, 3310 participated in the TGES (response rate: 87.3%). After applying exclusion criteria, the data of 3274 individuals were analyzed for this report. The overall prevalence of PEX was 3.63% (95% CI:2.67-4.58) in this study. 81.1% of PEX cases were bilateral. The prevalence of PEX increased significantly with advancing age in a linear trend from 2.38% (95%: 1.27-3.48) in the age group 60-64 years to 6.48% (95%: 2.02-10.95) in the age group ≥80 years (OR = 1.05, p = 0.008). According to the multiple logistic regression model, advancing age (OR: 1.06, p = 0.002) and the presence of cataract (OR: 5.02, p < 0.001) were significantly associated with increased odds of PEX. CONCLUSION: The results showed a lower prevalence of PEX in the Iranian elderly compared to previous studies on the elderly population. Advancing age and cataracts were the only associated factors of PEX in the present study.

Corneal densitometry and associated factors in an elderly population.

CLINICAL RELEVANCE: Knowing normative corneal optical density (COD) values is important for identifying pathologic corneal changes. BACKGROUND: The aim of this work is to determine the distribution and associated factors of COD in the elderly population. METHODS: This report is a part of a cross-sectional population-based study conducted on the elderly population (≥60 years) of Tehran, Iran from Jan 2019 to Jan 2020. Using a multi-stage stratified random cluster sampling method, a total of 160 clusters were randomly selected from 22 districts of Tehran city. Study participants underwent a complete ocular examination including measurement of visual acuity, refraction, and slit-lamp biomicroscopy. Corneal densitometry was evaluated using the Pentacam HR. Generalized estimating equation (GEE) models were used to investigate associations of COD with study variables. RESULTS: A total of 3633 eyes from 2068 individuals were analysed. Of these, 1256 (60.7%) were female, and the mean age of the individuals was 66.42 ± 5.28 (60 to 95) years. The mean entire COD was 21.96 ± 4.45 greyscale unit (GSU) (95% CI: 21.57-22.34). There was a statistically significant difference in the mean COD between the anterior, central, and posterior layers (p < 0.001); the highest and lowest average COD was related to the anterior and posterior corneal layers, respectively. The lowest and highest mean COD were observed in the 0-2 mm [17.21GSU (95% CI:16.87-17.55)], and 10-12 mm annular zones [31.4 GSU (95% CI: 30.89-31.91)], respectively (p < 0.001). According to the multiple GEE model, the COD had a statistically significant direct relationship with age, central corneal thickness, and mean keratometry, while it was significantly inversely associated with female sex, anterior chamber depth, white-to-white distance, and corneal volume. CONCLUSION: These normal values of COD in the present study could be used as reference data in older adults. The associated factors of COD should be taken into account to avoid misinterpretation of physiologic changes as pathologic processes.

A longitudinal study of local stereoacuity and associated factors in schoolchildren: The Shahroud Schoolchildren Eye Cohort Study.

CLINICAL RELEVANCE: Impaired stereoacuity is seen in some children without amblyopia, strabismus, and clinically significant refractive errors. Therefore, there are probably other factors affecting stereoacuity. BACKGROUND: The aim of this work was to investigate the longitudinal changes of local stereoacuity and associated factors in schoolchildren. METHODS: The present report is a part of the Shahroud Schoolchildren Eye Cohort Study. The target population was children aged 6 to 12 years in Shahroud, Iran. The second phase of the study was conducted in 2018 by re-inviting all participants in the first phase (2015). After an initial interview, study participants underwent optometric examination and ocular biometry. Stereoacuity was evaluated using Stereo Fly Test. Exclusion criteria were functional amblyopia, strabismus, significant refractive errors, probable ocular pathology/organic amblyopia in either of the two study phases, a history of intraocular surgery or ocular trauma, and incomplete data. RESULTS: The data of 4666 children were analysed for this report, of which 53.7% were male. The mean age of the studied participants in the second phase was 12.37 ± 1.71 years. The mean stereoacuity was 42.31 (95% CI: 42.05 - 42.57) seconds of arc in the first phase, which reduced to 51.72 (95% CI: 50.79-52.65) seconds of arc in the second phase (P < 0.001). The prevalence of poor stereoacuity was 0.17% (95% CI: 0.06-0.29) in the first phase, which increased to 3.94% (95% CI: 3.34-4.54) in the second phase (P < 0.001). According to the multiple linear regression, older age in the first study phase (ß = 0.011, P < 0.001), urban residence (ß = -0.019, P = 0.006), increased spherical anisometropia (0.038, P = 0.013), and increased axial length (ß = 0.062, P = 0.003) were significantly associated with reduction of stereoacuity (in log scale) after three years. CONCLUSION: In addition to the known risk factors of amblyopia, strabismus, and significant refractive errors, other factors are also associated with stereoacuity changes in children.

Central corneal thickness and its determinants in a geriatric population: a population-based study.

PURPOSE: To determine the distribution of central corneal thickness (CCT) and its determinants in an Iranian geriatric population. METHODS: This population-based study was conducted in 2019 in Tehran, the capital of Iran, using stratified multistage random cluster sampling. The study population was all residents ≥60 years of age. First, preliminary optometric and ocular health examinations were performed including the measurement of uncorrected and best-corrected visual acuity, objective and subjective refraction, anterior and posterior segment examination. The study participants then underwent corneal imaging using Pentacam HR. RESULTS: Out of 3791 invitees, 3310 participated in this study (response rate: 87.3%). The mean CCT and apex corneal thicknesses were 528 µ (95% CI: 526-529) and 529 µ (95% CI: 527-530), respectively. The highest and lowest mean corneal thickness was related to the superior (620 µ: 95% CI: 618-622) and the temporal (591 µ: 95% CI: 590-592) paracentral points, respectively. According to the multiple linear regression model, the CCT was significantly inversely related to keratometry readings (K1 and K2) and had a statistically significant direct relationship with intraocular pressure (IOP), corneal eccentricity (ECC), and corneal volume (CV) (all p values <0.05). The CCT was significantly higher in diabetic patients (p = 0.043). CONCLUSION: The CCT values in the geriatric Iranian population were lower than the values reported in most previous studies. The CCT is mostly influenced by IOP and corneal parameters (curvature, shape factor, and volume) and is not affected by demographic factors, refractive error, and ocular biometric components.

Distribution of Corneal Volume and Its Associated Factors in an Elderly Population: Tehran Geriatric Eye Study.

PURPOSE: The aim of this study was to determine the distribution of corneal volume (CV) using Pentacam and its relationship with demographic and ocular factors in an elderly population older than 60 years. METHODS: The present report is a part of the Tehran Geriatric Eye Study. The sampling was performed using the multistage stratified random cluster sampling method. The preliminary ocular examinations were performed for all individuals including visual acuity measurement, objective and subjective refraction, and slit-lamp biomicroscopy. Finally, study participants underwent anterior segment imaging and ocular biometry using Pentacam AXL. RESULTS: The mean CV was 57.92 mm 3 [95% confidence interval (CI): 57.76-58.08] in the whole sample. The mean CV was 57.69 mm 3 (95% CI: 57.52-57.87) after excluding diabetic patients. The mean CV was 57.79 mm 3 (95% CI: 57.57-58.01) and 58.04 mm 3 (95% CI: 57.83-58.26) in men and women, respectively. The mean CV was 57.96 mm 3 (95% CI: 57.71-58.21), 57.84 mm 3 (95% CI: 57.49-58.19), and 57.92 mm 3 (95% CI: 57.7-58.13) in individuals with emmetropia, myopia, and hyperopia, respectively. The CV decreased significantly with advancing age. Moreover, the anterior chamber depth, central corneal thickness, mean keratometry, anterior corneal asphericity (Q value), and posterior corneal astigmatism were significantly directly related to CV, whereas axial length and white-to-white distance had a statistically significant inverse association with the CV. CONCLUSIONS: Aging is one of the important factors in reducing CV that should be considered. Some other topographic and biometric indices also have a significant relationship with CV.

Receded near point of convergence as a predictor of mild cognitive impairment in the general geriatric population: results from a population-based study.

AIM: To investigate the relationship between near point of convergence (NPC) and mild cognitive impairment (MCI) in the general elderly population. METHODS: The present report is a part of the Tehran Geriatric Eye Study (TGES): a population-based cross-sectional study conducted on individuals 60 years of age and above living in Tehran, Iran using the multi-stage stratified random cluster sampling method. Cognitive status was assessed using the Persian version of the Mini-Mental State Examination (MMSE). All study participants underwent complete ocular examination including measurement of uncorrected and best-corrected visual acuity, objective and subjective refraction, cover testing, NPC measurement, and slit-lamp biomicroscopy. RESULTS: The data of 1190 individuals were analyzed for this report. The mean age of the participants analyzed was 66.82±5.42 (60-92y) and 728 (61.2%) of them were female. Patients with MCI had a significantly more receded NPC compared to subjects with normal cognitive status (10.89±3.58 vs 7.76±2.71 cm, P<0.001). In the multivariable logistic regression model and in the presence of confounding variables, a receded NPC was statistically significantly associated with an increased risk of MCI (odds ratio: 1.334, 95% confidence interval: 1.263 to 1.410, P<0.001). According to receiver operating characteristic (ROC) analysis, a cut point NPC> 8.5 cm (area under the curve: 0.764, P<0.001) could predict the presence of MCI with a sensitivity and specificity of 70.9% and 69.5%, respectively. CONCLUSION: A receded NPC can be clinically proposed as a predictor of MCI in older adults. It is recommended that elderly with a receded NPC>8.50 cm undergo detailed cognitive screening for a definite diagnosis of MCI. In this case, the necessary interventions can be carried out to slow down MCI progression to dementia.

P100 Wave Latency and Amplitude in Visual Evoked Potential Records in Different Visual Quadrants of Normal Individuals.

Purpose: Assessment of the pattern visual evoked potential (PVEP) responses in different areas of visual fields in individuals with normal vision. Methods: This study was conducted on 80 eyes of normal subjects aged 18-35 years. All participants underwent refraction and visual acuity examination. Visual evoked potential (VEP) responses were recorded in different areas of field. The repeated measure test was used to compare the P100 latency and amplitude of PVEP among different areas. Results: The repeated measures analysis of variance showed a statistically significant difference among different areas in terms of amplitude and latency of P100 (P = 0.002 and P < 0.001, respectively). According to the results, the highest and lowest amplitude of P100 was observed in inferior-nasal and superior areas, respectively. The highest and lowest latency of P100 was related to the temporal and inferior-nasal areas, respectively. Conclusion: This study partially revealed the details of local PVEP distribution in the visual field and there was a significant difference in the amplitude and latency of PVEP wave in different areas of the visual field.

Anterior and posterior corneal higher-order aberrations in early diagnosis and grading of keratoconus.

CLINICAL RELEVANCE: Evaluation of corneal higher-order aberrations can be used clinically to diagnose early cases of keratoconus as well as to classify the severity of keratoconus. BACKGROUND: To investigate the anterior and posterior corneal higher-order aberrations (HOAs) up to the sixth order and their ability to identify early keratoconus (KCN) as well as differentiate different severities of KCN using cross-validation analysis. METHODS: This prospective cross-sectional comparative study was performed at a tertiary eye hospital in Tehran, Iran, in 2019. The study sample consisted of 95 eyes of 95 patients with KCN and 53 eyes of 53 normal individuals. The eyes with KCN were classified into three groups based on the Amsler-Krumeich classification system: group 1 (mild KCN), group 2 (moderate KCN), and group 3 (severe KCN). Corneal wavefront analysis was performed using Pentacam HR. RESULTS: Based on the magnitude of AUC, posterior vertical secondary coma (Z5-1) had an excellent discriminant ability (AUC: 0.91) and anterior vertical coma (Z3-1) and anterior vertical secondary coma (Z5-1) had a good discriminant ability (0.8 < AUC < 0.89) for differentiating eyes with mild KCN from normal eyes. The anterior and posterior primary spherical aberrations (Z4°) had an excellent ability (AUC > 0.9), and anterior secondary spherical aberration (Z6°) had a good ability (AUC: 0.83) for differentiating moderate from mild KCN. In the differentiation of severe from moderate KCN, anterior and posterior primary aspherical aberrations (Z4°) had a good AUC value (AUC > 0.8). CONCLUSION: Coma-like aberrations had a good discriminant ability between normal eyes and eyes with mild KCN. Spherical aberrations showed a good ability for differentiating between different stages of KCN. The cut-off values reported in this study can be used for early detection of KCN as well as classification of KCN severity.