[ effect of rigid gas permeable contact lens fitting in corneal curvature, central thickness and volume]

Evaluation of the corneal curvature, central thickness and volume three months after fitting the Rigid Gas Permeable [RGP] contact lens in keratoconic eyes. Corneal topography maps of 25 keratoconic eyes with a negative history of using the RGP lens were evaluated by Oculus Pentacam. Corneal curvature in both surfaces of the cornea, central corneal thickness and corneal volume were evaluated before and three months after fitting the aspheric RGP lens. Three months after using the contact lens, decrease in central corneal thickness [-3.43 micro m, P=0.127], decrease in flattest anterior corneal surface power [-0.43D, P=0.339], decrease in anterior corneal steep power [-1.54D, P=0.358], decrease in posterior corneal flat power [-0.1D, P=0.121], an increase in posterior corneal steep power [0.02D, P=0.710] and an increase in corneal volume [0.27 mm[3] P=0.331] were not statistically significant. Lack of significant changes in corneal topographical parameters three months after using the RGP lens may indicate the non progressive nature of keratoconus in this period. Further studies with longer follow-up periods are suggested to obtain more accurate results

[Prevalence of convergence insufficiency in a population of university students]

Convergence insufficiency [CI] is one of the most important binocular vision disorders. Because there is no previous report on CI prevalence in an Iranian population, the purpose of this study is to estimate the frequency of CI in a population of 18 to 30 years old university students in the rehabilitation faculty of Iran University of Medical Sciences. 160 students aged 18 to 30 years [mean +/- SD = 21.7 +/- 2.8 age] that had no glasses or had worn glasses or contact lenses>/= 1 month with corrected or uncorrected visual acuity of 20/30 or better in both eyes and uncorrected refractive error less than or equal to -0.5 D to + 1.00 D, or /= 10 cm, exophoria at near >/=4 delta more than far measurements, insufficient fusional convergence amplitude according to sheard criterion, normal amplitude of accommodation according to Hofstetter formula [minimum age appropriate amplitude of accommodation= 15- 0.25 x age in years]. The prevalence of CI was calculated based on the abovementioned data. Regardless of accommodative condition, 10% of the study population showed CI disorder. 25% of this population showed lower amplitudes of accommodation compared to the normal accommodative values. Indeed, 7.5% were CI and 2.5% were pseudo CI. The results of the present study demonstrated a high frequency of CI in population of university students. Because of the symptoms of CI during near work activities such as reading and using computer, screening and applying appropriate treatments seem to be essential

[ comparative study between visual functions of affected and unaffected eyes in acute unilateral optic neuritis]

Optic neuritis causes some deficits in visual function in the affected eye and there are some differences in these functions between the affected and unaffected eyes. The purpose of the study is to compare visual functions of both eyes to demonstrate the minimum and maximum value of affection in patients with acute unilateral optic neuritis. Thirty patients [23 female, 7 male aged between 18 and 45 years] who 22 patients with retro-bulbar and 8 patients with anterior optic neuritis, enrolled in the study and their affected and unaffected eyes underwent visual function assessments. Visual acuity [VA], contrast sensitivity [CS], color vision [CV], and visual field [VF] [consist of MA and PSD] were examined for both eyes of all the patients and the significance of the differences between two eyes were calculated and compared by Independent T-test. According to our results, all the investigated visual functions consist of VA [t-test, t=7.29, P=0.00], CS [t-test, t=9.20, P=0.00], CV [t-test, t= -21.95, P=0.00], MD [t-test, t=5.29, P=0.01] except PSD [t-test, t=0.67, P=0.71] were affected by optic neuritis and there was a significant difference between the affected and unaffected eyes [P<0.01]. The most significant difference were found for contrast sensitivity with letters [P=0.00] and there wasn't any significance in the difference between two eyes for PSD parameter in VF [P=0.71]. Considering the most significant difference of contrast sensitivity between affected and unaffected eyes in patients with acute unilateral optic neuritis, it is suggested to pay more attention to the test in evaluating, diagnosis and follow up patients with acute unilateral optic neuritis

[Comparison of OCT pachymetry pattern in keratoconus suspect and normal subjects]

Comparison of pachymetry pattern of OCT finding in Keratoconus [KCN] suspect and normal subjects. Thirty-two KCN suspect eyes and Thirty- eight normal eyes in young subjects [20-30 year- old] were evaluated. Pachymetry pattern of frequency domain OCT [Visante] in different parts of cornea [thinnest point, inferior - superior thickness difference, inferior temporal - superior nasal thickness difference and thinnest point in 0-2 millimeter decent ration] were measured. There was a significant [p<0.0001] difference in normal and KCN suspect patients in all measurements. KCN suspects showed thinner cornea and more differences in corneal thickness measurements. Anterior frequency domain OCT seems to be suitable for evaluation of KCN suspect patients. It may be critical for refractive surgery candidate and may be used as Pentacam or OrbScan corneal imaging systems

[Keratoconus diagnosis criteria in ophthalmologist and optometrist]

To evaluate optometrist and ophthalmologist approach in KCN diagnosis. A questionnaire was introduced randomly to Iranian ophthalmologist and optometrist in two national and international congresses. The questionnaire consisted of 16 questions that some of them has related to KCN early diagnosis and lens fitting. Cronbach's Alpha was 0.594 in ophthalmologists and 0.603 among optometrist groups. 36.2% of optometrists and 18% of ophthalmologists believed that retinoscopic reflex is very important in KCN diagnosis. Bio-microscopy was believed to be important in 53.7% of optometrists and 48.7% of ophthalmologists. Corneal imaging was important in early diagnosis of KCN 55.8% of optometrists and 57.7% of ophthalmologists. Most of optometrists believed that retinoscopy is most important in KCN diagnosis. Both groups believed that bio-microscopy and corneal imaging are very important in KCN diagnosis. Educational courses should be considered for contact lens fitting, both for optometrists and ophthalmologists. Regular congresses and symposiums may be recommended

[Two cases of orthoptic training in middle-aged patients]

To report the results of orthoptic training in two middle-aged patients according to current theories. A 56-year-old female with decompensated exophoria and myopia and a 68-year-old male with decompensated esophoria and moderate hyperopia underwent vision therapy according to standard procedures for improving fusional vergences and ocular accommodation. Sheard and Percival criteria and reduction of patient's symptoms showed binocular visual improvement. Orthoptic training may improve binocular visual function [fusional vergence and accommodation] in middle-aged patients. Therefore, patient motivation and knowledge about orthoptic advantages and disadvantages and explaining the orthoptic methods in comparison with other methods in middle age patients may be helpful for reducing some binocular vision problems