Characterizing the Visual Cortex Function in Cognitive Task-Induced Mental Load: An Functional Magnetic Resonance Imaging Study.

Introduction: The mental load caused by simultaneous multitasking can affect visual information processing and reduce its ability. This study investigated the effect of mental load caused by cognitive tasks simultaneously with visual task on the number of active voxels in the visual cortex. Methods: This study recruited 22 individuals with a mean age of 24.72 ± 5.47 years. 3-Tesla functional magnetic resonance imaging (fMRI) was used to examine the functions of the visual cortex and amygdala region during three different task conditions: visual task alone, visual task with an auditory n-back task, and visual task with an arithmetic task. The visual stimuli consisted of Gabor patches with a contrast of 55% at spatial frequencies of 0.25, 4, and 9 cycles per degree (cpd). These were presented in three trials of eight blocks with a stimulation time of 12 sec and a rest time of 14 sec. Results: Activated brain voxels in the primary, secondary, and associated visual cortex areas were reduced in response to the mental load imposed by the n-back and arithmetic tasks. This reduction was greater for a spatial frequency of 0.25 cpd in the n-back task condition and spatial frequency of 9 cpd in the arithmetic task condition. In addition, the amygdala was stimulated in 2-back task and arithmetic task conditions. Conclusions: This study revealed a decline in the number of activated voxels of the visual cortex due to the mental load caused by simultaneous cognitive tasks, confirming the findings of previous psychophysical studies.

How long does the recovery of corneal sensitivity in different corneal regions take after LASEK?

AIM: To determine the corneal sensitivity recovery period after laser-assisted sub-epithelial keratectomy (LASEK) refractive surgery and investigate the effects of ablation depth on it. METHODS: In this study examinations were performed on 90 right eyes of 90 people (34 males and 56 females) with an age range of 20-35 and an average of 22.26±3.8 years old. A sensation of 5 corneal regions, including the center and 4 mid-peripheral regions, i.e., nasal, inferior, temporal, and superior, each at a distance of 2 mm from the center of the cornea were measured with a Cochet-Bonnet esthesiometer device in 3-time points including before LASEK, 1 and 3mo after the surgery, respectively. LASEK was performed on individuals with stabilized myopia of -1.00 to -7.00 diopters and astigmatism of less than 2.00 diopters. Furthermore, the individuals were divided into three groups regarding ablation depth. RESULTS: The highest level of corneal sensitivity before surgery was related to the center of the cornea (59.1±7.76), and the highest level of corneal sensitivity loss was also related to this region. The sensation of all measured corneal regions significantly reduced 1mo postoperatively and returned to their preoperative levels 3mo after surgery (mean of 5 corneal regions in levels of preoperation: 58.2±6.48, 1mo postoperation: 57.3±5.84, 3mo postoperation: 58.2±5.49; P<0.05). A significant relationship was found between ablation depth and corneal sensitivity changes in the center and temporal regions (P<0.05). CONCLUSION: Corneal sensitivity in myopia and low astigmatism decreases after LASEK and reaches the preoperative level within 3mo. The depth of ablation during surgery affected the recovery of corneal sensitivity.

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.

Comparison of anterior segment parameters of the eye between type 2 diabetic with and without diabetic retinopathy and non-diabetic.

AIM: To compare anterior segment parameters between two groups of type 2 diabetic with and without diabetic retinopathy (DR) and non-diabetic elderly subjects based on hemoglobin A1c (HbA1c) levels and status of DR. METHODS: This study was conducted on 997 residents aged 60y or over in Tehran, Iran. Diabetic group had HbA1c level ≥6.4% with no other systemic problems. The non-diabetic participants had normal eye findings and no systemic diseases. K1, K2, mean K, Q-value, anterior, central, posterior, and total corneal densitometric findings, anterior chamber volume (ACV), anterior chamber depth (ACD), corneal volume (CV), and pachymetry were measured by Pentacam AXL. RESULTS: A total of 678 non-diabetic (39% male) and 319 diabetic (35% male) subjects with mean age of 66.31±5.23 and 67.22±4.96y were examined, respectively. No statistically significant difference was found in anterior segment parameters between non-diabetic and diabetic groups (all P>0.05). However, middle, posterior, and total corneal densitometric values were statistically different between two groups after controlling the effects of confounders (P=0.014, 0.007, and 0.042, respectively). Corneal densitometric values in all layers, ACD, and ACV were different between diabetic subjects with and without DR (all P<0.05). In the diabetic group, only corneal densitometric values had a negative relationship with fasting blood sugar (P<0.001). ACD and ACV had a negative correlation with HbA1c levels (all P<0.05, r=-0.129 and -0.146, respectively). However, the relationships were not observed after controlling the confounders (P=0.938, 0.466, respectively). CONCLUSION: Considering the higher densitometric values of the cornea and lower ACD and ACV in diabetic subjects with DR, it is suggested that the examiners should perform comprehensive retinal examinations when faced with such conditions.

Binocular contrast sensitivity in patients with intermittent exotropia in relation to angle of strabismus and level of compensation.

Intermittent exotropia (IXT) causes photophobia, and photophobia has been studied by measurement of contrast sensitivity (CS). CS was reduced in children with IXT. We compared binocular CS (BCS) in patients with IXT and normal subjects in relation to the angle of strabismus and control of IXT. This case-control study was performed on 40 patients with IXT and 40 normal subjects who were examined with the CSV1000 CS device in mesopic (3 cd/m2) and photopic (85 cd/m2) conditions with and without a glare stimulus at 3, 6, 12, and 18 cycle/degree (cpd) spatial frequencies. The angle of strabismus and near stereoacuity were also measured. The patient's IXT compensation was graded based on the office control scale. The mean age for IXT and normal participants were 12.30 ± 0.60 (range, 6-18) and 11.00 ± 0.78 (range, 6-18) years, respectively (P = .34). The IXT patients had lower binocular CS than controls at all spatial frequencies (P < .001). The largest decrease in CS occurred at 6 cpd spatial frequency under mesopic condition (1.61 ± 0.07 vs 1.38 ± 0.15, P < .001) and photopic condition with glare (2.03 ± 0.06 vs 1.77 ± 0.13, P < .001). Patients with better control scores had higher levels of BCS; also, the score of BCS showed a significant decrease in patients with a deviation of 25 prism diopter or more, compared to those with less deviation. BCS correlated at 3 and 6 cpd with near stereoacuity (r = -0.652, P < .001 and r = -0.613, P < .001). Binocular CS in patients with IXT correlates with the angle of strabismus and level of compensation.

Does Long-Term Night Shift Work Cause Dry Eye in Hospital Nurses?

Purpose: To determine the long-term effects of night shift work on dry eye in hospital nurses. Methods: Each participant was evaluated four times, including at the beginning of the day shift (8 am), at the end of the day shift (2 pm), at the beginning of the night shift (8 pm), and at the end of the night shift (8 am), using the tear break-up time (TBUT) test and ocular surface disease index (OSDI) questionnaire. Results: The results showed significant differences in the TBUT and OSDI between the end of the day shift (2 pm) (10.26, 16.61) and the end of the night shift (8 am) (6.89, 38.59) relative to each other and relative to the beginning of the day and night shifts. As for the correlation between TBUT and OSDI, a significant correlation was found at all measurement times (correlation coefficient: -0.478, -0.707, -0.556, and -0.365, respectively) (p < 0.05). Conclusion: The results showed that the severity of dry eye increased after the night shift with variation over a 24-hr period. Moreover, a significant correlation was observed between TBUT and OSDI results at the beginning and at the end of the day and night shifts.

Dynamic Electrooculography Findings for Medial Rectus Myofascial Release in Esodeviation.

Purpose: To determine which mechanisms are operative in releasing the extraocular myofascial tissue in response to extraocular myofascial release (EOMR) and to evaluate the effect of EOMR on saccadic velocity and esodeviation angle in patients with convergence spasm. Methods: Fourteen patients with convergence spasm aged 20-35 participated in this research. The treatment included touching the medial rectus and its interrelated fascial tissue with the index finger pulp from over the eyelid for at least 300 s and applying very gentle and uniform pressure. We evaluated the saccadic velocity obtained from dynamic electrooculography (EOG) and the angle of deviation. The findings of dynamic EOG were used as a reliable quantitative method to assess eye movement function. Results: The amount of esodeviation decreased significantly at both far 2.39Δ, 95% confidence interval (CI) (1.27-3.52) (P = 0.002) and near 5.57Δ, 95% CI (4.67-6.47) (P = 0.001) after two sessions of EOMR in a week. There was no significant difference in saccadic velocities before and after treatment. Conclusion: In the short term, the EOMR only affects the static condition of the eye. Therefore, a significant improvement could be seen in the deviometric findings. However, the dynamic properties of the extraocular muscles did not improve and probably needed a more extended treatment period for acting the long-term mechanisms.

Changes in Refractive and Optometric Findings During Pregnancy.

Background: Pregnancy-induced changes in the physiological responses during the gestational period can affect the eye. This study aimed to evaluate the effect of pregnancy on visual, refractive, vergence, and accommodative status. Methods: In this cross-sectional study, twenty-five healthy pregnant women with a mean age of 29±3.1 were examined. All of the subjects underwent comprehensive ophthalmologic examinations, including anterior segment and fundus examinations and tonometry. Refractive error was determined in each trimester using Autokeratometer. Furthermore, near the point of convergence (NPC), best-corrected visual acuity (BCVA), and near the point of accommodation (NPA) were measured. Data analysis was performed using SPSS version 22. To compare the data during pregnancy, repeated measures analysis of variance (ANOVA) was performed. Results: During pregnancy, in the right and left eye, spherical equivalent (SE) had a myopic shift from -0.13 to -0.35 D and +0.096 to -0.23 D, respectively (p=0.049 and p=0.020, respectively). Also, in the right and left eyes BCVA significantly decreased from -0.13 to 0.00 and -0.14 to 0.00 LogMAR, respectively (p=0.039 and p=0.045, respectively). NPA and NPC did not change statistically significantly during pregnancy (p=0.385, and p=0.801, respectively). Conclusion: Due to the unstable hormonal status, a myopic shift and decrease in BCVA occur during pregnancy. So, any change in their spectacle prescription, fitting of contact lenses, performing refractive surgeries, etc., during this period should be postponed.

Translation, cross-cultural adaptation and validation of the Computer Vision Syndrome Questionnaire into Persian (CVS-Q FA©).

PURPOSE: To translate, cross-culturally adapt and validate the Computer Vision Syndrome Questionnaire (CVS-Q©) into Persian. METHODS: This study was carried out in 2 phases: (1) the CVS-Q© was translated and cross-culturally adapted into Persian and (2) the validity and reliability of CVS-Q FA© were assessed in a cross-sectional validation study. An expert committee composed of 15 optometrists evaluated content validity (item-level (I-CVI) and scale-level (S-CVI) content validity index were calculated). A pretest was performed (n = 20 participants) to verify the comprehensibility of the questionnaire. A total of 102 computer users completed the final questionnaire. Criterion validity and diagnostic performance of the CVS-Q FA© were assessed by calculating sensitivity, specificity and receiver characteristic operator curve. Cronbach's alpha was calculated for the assessment of internal consistency and 46 participants refilled the questionnaire for the second time and the interclass correlation coefficient (ICC) and Cohen's kappa (κ) were evaluated for test-retest reliability. RESULTS: The translation and cross-cultural adaptation process was performed successfully according to accepted scientific recommendations without any major difficulties. The I-CVI was above 0.80 for all items (symptoms) except item 15 (feeling that sight is worsening) and the S-CVI was 0.92. The CVS-Q FA© showed good sensitivity (81.1%) and acceptable specificity (69.2%). Also, it achieved good internal consistency (Cronbach's alpha = 0.80) and test-retest reliability (ICC = 0.81 and κ = 0.65). CONCLUSION: The CVS-Q FA© was successfully translated, cross-culturally adapted, and validated into Persian. This study provides a valid and reliable tool for the assessment of computer vision syndrome among the Iranian working population.

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.

Is retinal nerve fibre layer thickness correlated with visual function in individuals having optic neuritis?

CLINICAL RELEVANCE: The existence of a correlation between the results of paraclinical retinal imaging and clinical tests such as contrast sensitivity can reduce time and cost in diagnosing optic neuritis (ON). BACKGROUND: To demonstrate whether changes of peripapillary retinal nerve fibre layer (RNFL) thickness are correlated with the results of visual acuity, contrast sensitivity and colour vision in eyes with acute ON. METHODS: Thirty patients with acute ON, 23 females and seven males, who had no previous history of ON in neither eye, were examined. Inclusion criteria were: subjects had spherical refraction of less than ±5D, no prior ON or optic disc swelling, no history of amblyopia or colour blindness, and no history or ophthalmoscopic evidence of glaucoma, diabetic retinopathy, or maculopathies. Visual acuity, contrast sensitivity and colour vision were tested and optical coherence tomography was performed for all patients after complete ophthalmologic examinations including refraction, biomicroscopy, and funduscopy with a 90D lens by a neuro-ophthalmologist. RESULTS: Thirty patients who were 18-45 years old entered the study. There was an inverse correlation between contrast sensitivity and nasal (r = -0.430, p = 0.018), inferior (r = -0.503, p = 0.005) and mean (r = -0.510, p = 0.004) RNFL thickness. The multiple linear regression model, after adjustment for age and sex, showed a significant association between visual acuity and nasal RNFL thickness (coefficient = 0.025, p = 0.032). There was also a significant inverse correlation between contrast sensitivity and nasal (coefficient = -0.003, p = 0.036), inferior (coefficient = -0.006, p = 0.010) and mean (coefficient = -0.007, p = 0.012) RNFL thickness. No significant correlation was found between colour vision and RNFL thickness. CONCLUSION: Contrast sensitivity is more correlated with changes in RNFL thickness in comparison with visual acuity and colour vision. Contrast sensitivity measurement therefore can be used as one of the first assessments in patients with ON.

Introducing a new method of retinoscopy for refraction of infants and young children: The “Mirza” tele lens retinoscopy

Purpose: This study aimed to evaluate the refractive error of the uncooperative infants and children with the new method of retinoscopy called the tele-lens (“Mirza”) retinoscopy. Methods: In the “Mirza” tele-lens retinoscopy, the examiner placed the trial lenses in 1/3 distance between the tested eye person and peephole of the retinoscope (22.2 cm far from the spectacle plane). First, the optical calculations were done to find the correction factors for this new method of retinoscopy. Second, the dry standard and “Mirza” tele-lens retinoscopy were performed in 78 eyes from 39 children aged 7–12 years with good cooperation and next, the procedure was repeated using cyclopentolate drops and then the results of the two methods were compared, and at the end, the dry “Mirza” tele-lens retinoscopy was done in the 60 eyes of 31 uncooperative infants with a mean age of 21.85 ± 8.79 months for evaluating the feasibility of the “Mirza” tele-lens retinoscopy procedure. The intraclass correlation coefficient (ICC) and Bland–Altman plot for assessment of agreement between the findings of two retinoscopic methods in dry and cyclo conditions were used. Results: The comparison between the dry standard and “Mirza” tele-lens retinoscopic results with means of 1.39 ± 1.43 and1.36 ± 1.39, respectively were not statistically significant (p > 0.05). Besides, comparing the mean cycloplegic results of two methods (standard vs. “Mirza” tele-lens), the difference was not statistically significant (2.37 ± 1.44 vs. 2.41 ± 1.37) (p > 0.05). Moreover, Two-way repeated measures ANOVA revealed no significant retinoscopy method × use of drops interaction (P = 0.103) in comparing two methods of the standard and “Mirza” tele-lens retinoscopy. ICC results indicated high agreement between two methods in both dry (ICC = 0.993) and cyclo (ICC = 0.989) conditions. (AU)

Objective and subjective evaluation of tear film in machine carpet weavers.

OBJECTIVES: The present study was conducted to evaluate the status of tear film objectively and subjectively in machine carpet weavers. METHODS: In this cross-sectional study, machine-made carpet weavers were compared with the controls who were selected from people working in other parts of the factory except for the production. A complete evaluation of ocular health was done for all participants. The blink rate, tear deformation Time (TDT), and ocular staining were evaluated as an objective assessment and the ocular surface disease index (OSDI) was used for a subjective assessment of the tear film status. The results were compared between the two groups using the SPSS software. RESULTS: The results of 46 weavers (mean age: 38.43 ± 6.10 years) and 46 controls (mean age: 33.20 ± 8.40 years) were analyzed. The mean of blink rate and OSDI score were significantly higher in weavers (Blink rate: 20.67 ± 4.18 blink/min, OSDI: 22.59 ± 9.51) in comparison with controls (Blink rate: 14.00 ± 3.30 blink/min, OSDI: 6.22 ± 4.78, P < .001). The mean TDT value of the weavers was significantly lower compared with the controls (10.27 ± 3.01 and 16.58 ± 4.18 s respectively, P < .001). Ocular surface staining was seen among 60.9% of weavers while there was 6.5% in the controls (P < .001). Based on the TDT test and OSDI results together, the percentage of dry eye in the weavers was 43.5% and that in the non-weavers was 2.2%, which showed that the relationship between weaving and dry eyes was statistically significant (P < .001). CONCLUSIONS: The results indicate that increased symptoms and decreased tear stability in weavers compared with non-weavers lead to more tear film abnormalities in these individuals.

Distribution of near Point of Convergence, near Point of Accommodation, Accommodative Facility and Refractive Errors in a Rural Population Living in Northern Iran.

Purpose: To evaluate near point of convergence (NPC), near point of accommodation (NPA), and accommodative facility (AF) in order to determine their normative data in a rural population.Methods: The target population for this population-based, cross-sectional study was people living in rural areas. Each subject underwent extensive optometric and ophthalmic examinations, including the measurement of visual acuity, refraction, NPA, NPC, and AF.Results: The data of 1113 individuals was analyzed of whom 58.8% (n = 576) were women. The mean age of the participants was 15.26 ± 7.38 years (range: 6-30 years). The mean spherical equivalent of the subjects was 0.16 ± 0.63 D. The prevalence of myopia, hyperopia and astigmatism was 16.28% (13.97-18.58), 5.97% (4.49-7.44), 11.93% (9.91-13.95) in this study, respectively The mean and 95% confidence interval of NPC, NPA, and binocular accommodative facility (BAF) was 6.99 cm (6.84-7.15), 9.91 cm (9.71-10.11), and 9.84 cpm (9.63-10.06), respectively. A significant correlation was found between age and the parameters such that all evaluated parameters worsened significantly with age (P < .001).Conclusion: The results of the present study showed the normal ranges of NPA, NPC, and BAF in a 6-30 year-old population living in rural areas of northern Iran. These parameters changed significantly with age.

Predictor factors of prism effectiveness in young adults with convergence insufficiency.

Clinical relevance: The findings of this study can be useful in the process of patient selection as well as in optimising the prescription of the prism in patients with convergence insufficiency.Background: To determine the relationship between the demographic variables and baseline clinical characteristics with the prism effectiveness in young adults with convergence insufficiency.Methods: Sixty-four young adults with convergence insufficiency entered a randomised clinical trial and were randomly assigned to either treatment or placebo groups. For participants in the treatment group, the near optical correction containing base-in prism was determined based on the Sheard's criterion. Participants in the placebo group received near optical correction. After three months of using the assigned correction, the outcome examinations were performed.Results: In the univariate analysis, a remote near point of convergence, a higher baseline symptoms score, and a higher prescribed prism power showed a significant relationship with the increase in prism effectiveness. A significant inverse relationship was found between the near positive fusional vergence, vergence facility, and prism adaptation rate with the prism effectiveness. Based on the results of the multiple regression, the prism adaptation rate was the only independent predictor factor of prism effectiveness, so that the prism effectiveness increased by 0.60 for each per cent reduction in prism adaptation rate.Conclusion: Prism adaptation is the only independent predictive factor of prism effectiveness in young adults with convergence insufficiency. Based on the findings of the present study, it is recommended that careful assessment of prism adaptation be considered before considering prism prescription.

Introducing a new method of retinoscopy for refraction of infants and young children: The "Mirza" tele lens retinoscopy.

PURPOSE: This study aimed to evaluate the refractive error of the uncooperative infants and children with the new method of retinoscopy called the tele-lens ("Mirza") retinoscopy. METHODS: In the "Mirza" tele-lens retinoscopy, the examiner placed the trial lenses in 1/3 distance between the tested eye person and peephole of the retinoscope (22.2 cm far from the spectacle plane). First, the optical calculations were done to find the correction factors for this new method of retinoscopy. Second, the dry standard and "Mirza" tele-lens retinoscopy were performed in 78 eyes from 39 children aged 7-12 years with good cooperation and next, the procedure was repeated using cyclopentolate drops and then the results of the two methods were compared, and at the end, the dry "Mirza" tele-lens retinoscopy was done in the 60 eyes of 31 uncooperative infants with a mean age of 21.85 ±â€¯8.79 months for evaluating the feasibility of the "Mirza" tele-lens retinoscopy procedure. The intraclass correlation coefficient (ICC) and Bland-Altman plot for assessment of agreement between the findings of two retinoscopic methods in dry and cyclo conditions were used. RESULTS: The comparison between the dry standard and "Mirza" tele-lens retinoscopic results with means of 1.39 ±â€¯1.43 and1.36 ±â€¯1.39, respectively were not statistically significant (p > 0.05). Besides, comparing the mean cycloplegic results of two methods (standard vs. "Mirza" tele-lens), the difference was not statistically significant (2.37 ±â€¯1.44 vs. 2.41 ±â€¯1.37) (p > 0.05). Moreover, Two-way repeated measures ANOVA revealed no significant retinoscopy method × use of drops interaction (P = 0.103) in comparing two methods of the standard and "Mirza" tele-lens retinoscopy. ICC results indicated high agreement between two methods in both dry (ICC = 0.993) and cyclo (ICC = 0.989) conditions. CONCLUSIONS: The "Mirza" tele-lens retinoscopy method can be performed with satisfactory results in infants and children who do not cooperate for the standard procedure of measuring the refractive errors.

Visual Acuity Improvement in Adult Anisometropic Amblyopes After Active Vision Therapy.

PURPOSE: The aim of this study is to evaluate the effect of active vision therapy in adults with anisometropic amblyopia. METHODS: In this study, 20 adults with anisometropic amblyopia aged from 17-35 years old were treated for five sessions (one session per week) with vision therapy techniques which include accommodative rock, vergence rock, and saccadic training. Moreover, computerized vision therapy was performed by Optosys® software. Also, patients had been given a daily program for home training, including accommodative and vergence rock, and Optosys® software. Best corrected visual acuity (BCVA) was measured before and after treatment. RESULTS: Comparison of data using t-test showed that BCVA significantly improved after the vision therapy period. Initial BCVA (Log MAR) was 0.37±0.04 (mean±standard deviation) which improved to 0.14±0.03 after treatment. The correlation between initial BCVA and the amount of improvement showed that the worse the pre-treatment visual acuity was, the greater improvement that occurred. CONCLUSION: The improvement of visual acuity in adult anisometropic amblyopes showed that there are some degrees of plasticity in the visual system of amblyopic patients even in adulthood. Thus, therapists should give the chance of treatment to adult amblyopes.

Evaluation of contrast sensitivity and color vision in lead and zinc mine workers.

Purpose. This study was performed to determine achromatic contrast sensitivity and color vision in lead and zinc mine workers. Methods. A total of 230 male workers, who had been working in mine and had been in contact with minerals for at least 1 year, were considered as the case group, and the age of 90 years matched men who have not been in contact with minerals, being regarded as the control group. Contrast sensitivity was assessed using the Freiburg test at three frequencies of 1, 5 and 15 cycles of degree and under low mesopic light condition by two gratings and Landolt C stimuli. Color vision was assessed using the Farnsworth D-15 test under high mesopic light condition. Both tests were carried out monocularly. Data were analyzed using version 22 SPSS software. Results. There was a significant difference between studied groups with Landolt C stimulus in all three frequencies 1, 5 and 15 cycles per degree (p=0.009, p=0.016 and p=0.003). With Grating stimulus, there was a significant difference between the two groups in frequencies of 1 and 15 cycles per degree but at frequency of 5 cycles per degree, there was a border difference (p<0.0001, p=0.051 and p=0.008). A significant difference was observed between color confusion indexes of the two groups (p<0.0001). Conclusion. Chronic exposure to mineral in lead and zinc mine may cause color vision deficiency and decrease in contrast sensitivity. It is recommended that Farnsworth D-15 and Freiburg contrast sensitivity tests would be involved in the early diagnosis of neurodegenerative and visual disorders in workers exposed to minerals.

Electroretinogram Changes Following Sequential Panretinal Photocoagulation for Proliferative Diabetic Retinopathy.

PURPOSE: To evaluate changes in electroretinogram (ERG) response over the course of multiple sessions of panretinal photocoagulation (PRP) in patients with proliferative diabetic retinopathy (PRP). METHODS: A prospective cohort study of 11 patients with PDR who required PRP was conducted. PRP was completed over three sessions. Each patient had five ERGs done: baseline, 1 week after each PRP session, and 6 weeks after the last session of PRP. Dark-adapted 0.01 ERG, Dark-adapted 3 ERG, Dark-adapted 10 ERG, Light- adapted 3 ERG, and Light-adapted 30 Hz flicker ERG were done. The mean change in a- and b-wave amplitudes as well as implicit times compared to baseline was analyzed. RESULTS: A significant reduction in peak amplitudes of both a- and b-waves and delay in latencies were observed in all responses (p<0.05). The absolute amplitude reduction and delay in latency were higher for scotopic b-waves (p<0.05). The root mean square (RMS) of Dark-adapted 10.0 ERG (p<0.05) and total mean amplitude changes of a- and b-waves (p<0.001) were reduced after each laser session; however, the magnitude of change was not different between the first, second, or third sessions of PRP, and each session showed a similar deterioration rate of ERG parameters comparing to each other (p=0.4 for RMS and p=0.2 for total mean amplitude changes). In addition, the results indicated recovery of the amplitude and latency of ERG waves after 6 weeks from the final treatment (p<0.001) although not to baseline levels. CONCLUSION: ERG findings following PRP show reduced retinal function after each session which partially recovers by 6 weeks after the completion of therapy. Clinicians should be mindful of these changes when planning the treatment course for patients with PDR.

The effect of alternate occlusion on control of intermittent exotropia in children.

PURPOSE: The aim is to investigate the effect of alternate occlusion on control of intermittent exotropia in children 3 to 8 years old. METHODS: The ability of 28 children to control of the deviation at far and near was evaluated based on 3-point and 6-point control scales. Stereopsis and fusion were assessed using the Titmus and Worth 4-dot tests, respectively. Two-hour alternate daily occlusion was prescribed for children with no dominancy. For children with a dominant eye, 2-h occlusion of the dominant eye for 5 days and the non-dominant eye for 2 days. All measurements were repeated at 3, 6, and 9 months after the treatment. RESULTS: For all children with a mean age of 4.7 ± 1.56 years, deviation control at far improved significantly after 3, 6, and 9 months of treatment using both control scales when compared with baseline (p = 0.005 after 3 months and p = 0.008 after 6 and 9 months for the 3-point scale, and p < 0.001 after 3 and 6 months and p = 0.010 after 9 months for the 6-point scale). Control at near showed a significant improvement after 3, 6, and 9 months of treatment based on the 6-point scale (p = 0.007 for 3 months, p = 0.004 for 6 months, and p = 0.014 for 9 months). Near stereopsis improved significantly after 9 months of treatment (p = 0.043). CONCLUSION: Alternate occlusion is significantly effective on control of intermittent exotropia. As a result, it can be used as a useful method to postpone or even eliminate the need for surgery in intermittent exotropia.