فرشاد عسگری زاده

To investigate and determine the values of corneal elevation, astigmatism and best fit sphere (BFS) in anterior and posterior surfaces of the cornea in different stages of keratoconus (KCN) and to determine their differences and correlations
In this retrospective study, 161 eyes of 161 KCN patients with mean age ± SD of 22.35 ± 6.10 years were examined using Pentacam HR (Oculus, Germany). Corrected distance visual acuity, spherical refractive error, astigmatism and outcomes of Scheimpflug-based imaging system were assessed based on the Amsler-Krumeich KCN classification.
The mean corrected distance visual acuity was different between all stages of KCN (Kruskal-Wallis, p≤0.001). Magnitude of corneal anterior and posterior BFS, elevation and astigmatism were different in 4 stages of KCN (Kruskal-Wallis test, P≤0.5). There were strong correlations between anterior and posterior astigmatism in grade 1 (p≤0.001, r=0.924), anterior and posterior elevation in grade 2 (p≤0.001, r=0.903) and anterior and posterior BFS in total group of KCN (p≤0.001, r=0.923).
This study showed the values of corneal elevation, astigmatism and BFS in anterior and posterior surfaces of the cornea in different stages of KCN. Also, we determined strong correlation between some anterior and posterior parameters but not for all. Our findings can be used in clinical assessment of KCN.
Keywords
Keratinous; Corneal astigmatism; Best fit sphere; Corneal elevation; Refractive error
Main Subjects

The one step in evaluation of binocular vision is determination of type and amount of deviation. For this purpose objective and subjective methods were used. The purpose of this study is was to compare the measured heterophoria with objective (cover test) and subjective methods (von Graefe, Maddox rod, phi phenomenon) considering motor dominancy. In this semi-experimental study, 100 students of Zahedan University of medical sciences who had inclusion criteria, selected, randomly. Refractive errors and dominant eye were determined by retinoscopy and hole in the card test, respectively. The deviation was measured objectively by using alternate prism cover test and subjectively by von Graefe, Maddox rod and phi phenomenon tests so dominant and nondominant eye were fixed alternatively. Data were analyzed in SPSS-15 software using repeated measurement of ANOVA and correlation tests. There were considerable statistical difference between different measurement methods considering the dominancy of fixator eye (p<0.001). In the correlation test, the most and least correlations were related to phi phenomenon (dominant eye fixator) and phi phenomenon (non dominant eye fixator) and von Graefe and phi phenomenon (with dominant eye fixator), respectively. The most accurate heterophoria measurement methods were phi phenomenon, cover test, Maddox rod and von Graefe, respectively. Although accuracy of phi phenomenon was more than other methods in determination of deviation, because subjective methods cannot be used in all conditions, cover test is the best method in measuring eye deviation. Also, measured deviations in all of methods were lower when dominant eye was fixator.

To compare the effect of different deviation measurement echniques and different lens powers on gradient accommodative convergence to accommodation (AC/A) ratio. We randomly selected 78 eligible students of different majors from Zahedan University of Medical Sciences. Following retinoscopy for refractive errors, alternate prism cover test, von Graefe and Maddox rod without additional lenses and with ±1, ±2 and ±3 D lenses were performed for measurement of deviation at near and determination of gradient AC/A Ratio. Data were analyzed using within subjectfactorial repeated measurement ANOVA and correlation tests. Mean AC/A ratio was 3.6, 3.7 and 4 prism diopter to diopter using alternate cover test, Maddox rod and von Graefe methods, respectively (P=0.2). The highest and lowest AC/A ratios were related to von Graefe method with +3D and cover test with -1D lens power, respectively. Only differences between AC/A ratios with -1 and +2 lenses as well as with -1 and +3D were significant (P<0.05). For all different deviationmeasurement methods, AC/A ratios with plus lenses were higher than minus lenses. The type of deviation measurement method had no effect on AC/A ratio but selected lens power affected the results. We recommend using 2 or 3 diopter instead of 1 diopter lenses to avoid possible effects of depth of focus.

Introudction: Optometrists frequently encounter patients with migraine headache, suspecting that visual anomalies ‎might trigger such headaches. Due to controversial results on the relationship between migraine ‎headaches and refractive errors, this study aimed to investigate the relationship between refractive ‎errors and migraine.‎ ‎ In this case-control study, 60 patients with neurologically diagnosed migraine in the study group and ‎‎60 in the control group were studied. At first, the patients were screened by standard headache ‎questionnaire and the diagnosis was approved by a neurologist. The refractive errors were determined ‎by retinoscopy and corrected if necessary. The control group was selected from the individuals ‎matched based on sex and age. The data were analyzed in SPSS 13, using Mann-Whitney U test and ‎multiple logistic regression. Due to the high correlation between the spherical equivalent of the right ‎and left eyes, only the results of the left eye were presented.‎ ‎ In this study, the means of the sphere in the case and control groups were 0.12‎‏ ± ‏‎0.53 D and 0.04‎‏±‏‎1.58 ‎D (P>0.05) while the mean of the spherical equivalent in the study and control group was –0.38‎‏±‏‎1.75 ‎and –0.14‎‏±‏‎1.74 D (P>0.05). The mean of astigmatism in the study and control group was –0.85‎‏±‏‎0.88 ‎and –0.5‎‏±‏‎1.0 D.