[Relationship between central corneal thickness, intra ocular pressure and visual field in normal tension and primary open angle glaucoma]

Glaucoma is one of the most important cause of blindness wordwide. Exact determination of intra ocular pressure is important for the diagnosis and decision making about glaucoma treatment. Central corneal thickness is considered as effective factor on intra ocular pressure and visual field defect. This study was carried out to determine the relationship between central corneal thickness, intra ocular pressure and visual field in normal tension and primary open angle glaucoma. This descriptive study was carried out on 45 eyes with normal tension glaucoma and 45 eyes with primary open angle glaucoma in Al-Zahra ophthalmology hospital in Zahedan, Iran during 2010. Intra ocular pressure and central corneal thickness were measured by Goldman tonometer and pachymeter and visual field exanimated by Humphrey perimeter. Data were analyzed using SPSS-16, paired t-test, ANOVA, Mann-Whitney and Pearson correlation tests. There was significant correlation between central corneal thickness and intra ocular pressure [r=0.309, P<0.05]. A significant difference was detected in intra ocular pressure between two type of glaucoma [P<0.05]. Mean value of central corneal thickness in patient with mild visual field defect was higher than severe visual field defect but there was not significant statistical difference between central corneal thickness and visual field defect in subjects with glaucoma. This study indicated that increasing corneal thickness is accompanied with intra occular presure

[ cross dominancy and structural disorders of head and vertebral column]

Background and aim: The cross dominancy [CD] implicates as a condition that dominant eye and dominant hand are situated in opposite sides of a body. This condition can produce malformation and structural disorders in head posture and vertebral column. The aim of this study was to investigate the relationship between CD and structural disorders in vertebral column and head posture in students of Zahedan University of Medical Sciences

Methods: In this cross-sectional study, 300 students of Zahedan University of Medical Sciences were randomly selected and their dominant eye was determined by Miles test. Then subjects were divided into two groups [with cross dominancy and unilateral dominancy]. The presence of malformations of vertebral column and head posture were determined by checker board and plumb line. The data were analyzed using descriptive and analytical [Chi square] statistical tests

Results: The results of the present study demonstrated that 76 out of 300 students [25.3%] had cross dominancy [CD]. There were a significant difference between CD and scoliosis [P<0.001] or shoulder un-leveling [P=0.03] in two groups, but not between forward head posture [P=0.10] and chin deviation [P=0.22] with CD in two groups

Conclusion: The scoliosis and shoulder un-leveling had higher prevalence in CD subjects that is due to weak muscular support of vertebral column in coronal plane, but because of strong muscular support of vertebral column in sagittal plane, CD had not any considerable effect on chin deviation and forward head posture

[Effect of age on stereopsis]

To evaluate the effect of age on stereopsis. We evaluated stereoacuity using TNO and titmus test after full correction of refractive errors in 87 randomly selected subjects aged 5-80 years. There was a significant relashionship between stereopsis and age such that stereoacuity increased with aging [ANOVA, P<0.001]. Stereopsis decreases with aging and therefore age of the patient should be considered in this regard

[ investigation of relationship between binocular vision status and migraine headaches]

According to controversial results between migraine headaches and binocular vision anomalies, this study was designed to investigate the relationship between some parameters of binocular vision refractive errors and migraine headache. In this case-control study, 30 patients with neurologically diagnosed migraine who had inclusion criteria were selected as case group and 30 persons with no migraine headache were selected as control group. First, patients were screened by standard headache questionnaire and diagnosis refined by neurologist. The Refractive errors were determined by retinoscopy and were corrected. Then near point of convergence, jump convergence, stereopsis, fusional reserves and far and near deviation were determined. Data were analyzed by SPSS.15 software, using Man-Withney U test and multiple logistic regressions. The mean of near phoria, stereopsis, far positive fusional reserve, far negative fusional reserve, near positive fusional reserve, near negative fusional reserve in case and control groups were 6.5 +/- 2.85, 8.3 +/- 6.72 pd, 49.0 +/- 26.11, 154.17 +/- 333.82 sec/arc, 10.7 +/- 2.76, 6.07 +/- 5.07, 18.2 +/- 4.7, 11.0 +/- 7.37, 16.5 +/- 4.49, 13.97 +/- 8.72, 22.7 +/- 5.22 and 14.67 +/- 9.25 pd, respectively. The means of above parameters and jump convergence was significantly different between two groups [P<0.05]. However; no significant difference was observed between two groups for other variables [P>0.05]. In multiple logistic regression only jump convergence, far positive fusional reserve and near positive fusional reserve stayed in model [P<0.05]. This study showed higher rates of binocular vision anomalies [abnormal jump convergence, higher amounts of near deviation, abnormal positive and negative fusional convergence and reduced stereopsis] in migraine group than control. Hence, people who experience migraine headaches should be referred to their optometrist regularly to evaluate their binocular vision statuses

[ effectiveness of pencil pushup training and office-based vision therapy for treatment of convergence insufficiency]

To compare the effectiveness of pencil pushup training [PPT] versus office-based vision therapy in patients with convergence insufficiency. Sixty students of Zahedan Medical University with convergence insufficiency were randomly selected. After determining refractive error [by retinoscopy using cyclopentolate 1%, if needed], near point of convergence [by millimeter ruler], near heterophoria [by alternate prism cover test] and positive relative convergence [by prism bar]; subjects were divided into two groups to receive PPT [3 times daily for 10 min], or office prism training [2 times each week for 30 min]. Subjects were re-examined 4 and 8 weeks after initiation of treatment. Independent samples t-test showed that near point of convergence, phoria and positive relative convergence were not statistically different between the two groups before treatment. After 4 and 8 weeks of treatment only positive relative convergence was different between the two groups. Repeated measurement ANOVA showed considerable difference between the two groups in general but the Bonferroni test showed that the observed difference was related only to positive relative convergence. PPT and office-based vision therapy are comparable for treatment of convergence insufficiency

[ effect of anisometropia on stereopsis]

For good stereopsis, the two retinal images should have similar clarity, shape, and size. Anisometropia is one of the factors which has affect on stereopsis. The purpose of this study was investigation of induced anisometropia effect on binocular function and stereopsis. In this semi experimental study, a total of 135 students from Zahedan University of Medical Sciences who had inclusion criteria were selected randomly. At the beginning of the work, the refractive errors of the subjects were determined and corrected with retinoscop and their stereopsis measured using T.N.O test. Subsequently, this hyperopic and myopic anisometropia induced by use of negative and positive spherical lenses [power 1, 2, 3 diopter] in trial frame in front of one eye and in each state stereopsis measured again. In agreement and against the rule astigmatic anisometropia induced by positive cylindrical lenses in 180 and 90 degree axes and stereopsis measured again. Data were analyzed by SPPS. 14 software using within subjects factorial and repeated measurement ANOVA test. This study showed that both type and amount of anisometropia had significant effect on stereopsis [P<0.001]. The mean of stereopsis before intervention was [36.42 +/- 12.65]. The most and least reduction of stereopsis were related to 3D hyperopic anisometropia [339.42 +/- 125.1] and 1D with the rule astigmatic anisometropia [36.57 +/- 12.6], respectively. The mean of stereopsis before and after different type and amount of induced anisometropia were significantly different [P<0.001]. The result of this study showed that with increasing of anisometropia, stereoacuity decreases. Therefore, low degree of anisometropia, even 1D, can decrease both stereopsis and binocular function and thus, the amendment of stereopsis is necessary