Development, comparison, and internal validation of prediction models to determine the visual prognosis of patients with open globe injuries using machine learning approaches.

INTRODUCTION: Open globe injuries (OGI) represent a main preventable reason for blindness and visual impairment, particularly in developing countries. The goal of this study is evaluating key variables affecting the prognosis of open globe injuries and validating internally and comparing different machine learning models to estimate final visual acuity. MATERIALS AND METHODS: We reviewed three hundred patients with open globe injuries receiving treatment at Khatam-Al-Anbia Hospital in Iran from 2020 to 2022. Age, sex, type of trauma, initial VA grade, relative afferent pupillary defect (RAPD), zone of trauma, traumatic cataract, traumatic optic neuropathy (TON), intraocular foreign body (IOFB), retinal detachment (RD), endophthalmitis, and ocular trauma score (OTS) grade were the input features. We calculated univariate and multivariate regression models to assess the association of different features with visual acuity (VA) outcomes. We predicted visual acuity using ten supervised machine learning algorithms including multinomial logistic regression (MLR), support vector machines (SVM), K-nearest neighbors (KNN), naïve bayes (NB), decision tree (DT), random forest (RF), bagging (BG), adaptive boosting (ADA), artificial neural networks (ANN), and extreme gradient boosting (XGB). Accuracy, positive predictive value (PPV), recall, F-score, brier score (BS), Matthew correlation coefficient (MCC), receiver operating characteristic (AUC-ROC), and calibration plot were used to assess how well machine learning algorithms performed in predicting the final VA. RESULTS: The artificial neural network (ANN) model had the best accuracy to predict the final VA. The sensitivity, F1 score, PPV, accuracy, and MCC of the ANN model were 0.81, 0.85, 0.89, 0.93, and 0.81, respectively. In addition, the estimated AUC-ROC and AUR-PRC of the ANN model for OGI patients were 0.96 and 0.91, respectively. The brier score and calibration log-loss for the ANN model was 0.201 and 0.232, respectively. CONCLUSION: As classic and ensemble ML models were compared, results shows that the ANN model was the best. As a result, the framework that has been presented may be regarded as a good substitute for predicting the final VA in OGI patients. Excellent predictive accuracy was shown by the open globe injury model developed in this study, which should be helpful to provide clinical advice to patients and making clinical decisions concerning the management of open globe injuries.

Identification of a Missense Mutation in GJA8 Gene in an Iranian Family with Autosomal Dominant Congenital Cataract.

Purpose: To identify the causative mutations of autosomal dominant (AD) congenital cataracts in a large Iranian family. Methods: The complete and accurate family history and clinical information of participants were collected. A total of 51 family members, including 22 affected and 29 unaffected individuals, were recruited in this study. We performed whole exome sequencing to reveal pathogenic mutation. We used amplification refractory mutation system polymerase chain reaction and Sanger sequencing techniques to confirm segregation in patients and also to rule it out in the healthy participants. Results: A known missense mutation, c.827C>T (S276F), in GJA8 was identified. This mutation was confirmed in all patients. Neither all healthy family members nor 100 healthy individuals who served as controls from general population had this mutation. Conclusion: The missense mutation c. 827C>T in the GJA8 gene is associated with AD congenital lamellar cataract with complete penetrance in a six-generation Iranian family.

Long-term Outcomes of Collagen Crosslinking for Early Keratoconus.

PURPOSE: To evaluate the long-term outcomes of collagen crosslinking in early keratoconus. METHODS: Thirty eyes of twenty patients with early keratoconus were enrolled. Uncorrected visual acuity (UCVA), best spectacle corrected visual acuity (BSCVA), objective refraction, subjective refraction, corneal topography and pachymetry were assessed before and 3, 6, 12 months and 9 years after performing collagen crosslinking surgery. RESULTS: The patients' mean age was 31.2 ± 5.59 years at nine-year follow-up (range, 25-44 years). The means of preoperative UCVA and BSCVA were 0.57 ± 0.34 and 0.15 ± 0.12 logMAR, respectively, and these values remained stable at the final follow-up (P = 0.990 and P = 0.227, respectively). The mean objective spherical equivalent decreased considerably from -6.00 ± 4.05 D preoperatively to -5.22 ± 3.71 D at the final follow-up (P < 0.05). The mean subjective spherical equivalent was -4.25 ± 2.87 D preoperatively and this value was stable at the last follow-up (P = 0.92). No considerable difference was found between the post- and preoperative mean objective cylinder values (P = 0.34). The mean subjective cylinder value changed significantly from -4.05 ± 1.85 D preoperatively to -3.1 ± 1.42 D at the final follow-up (P < 0.05). The mean central corneal thickness was 496.97 ± 45.95 µm preoperatively and this value was stable at nine-year follow-up (P = 0.183). No significant difference was found between the pre- and postoperative mean maximum and mean minimum corneal curvature values (P = 0.429 and P = 0.248, respectively). There were no significant postoperative complications. CONCLUSION: Corneal crosslinking in early keratoconus seems to be a safe procedure that can effectively stabilize UCVA, BSCVA, subjective SE and CCT, while improving objective spherical equivalent.

Correlation between keratometry and corneal incision before and after phaco surgery.

INTRODUCTION: Cataract is a common cause of vision loss and blindness in humans. After surgical management of cataract, all efforts should be focused on reducing postoperative astigmatism thus providing an excellent vision to patients. AIM: To determine the relationship between corneal incision and refraction changes before and after phacoemulsification surgery in 300 patients undergoing cataract surgery in Khatam hospital in Mashhad, Iran from January 2017 to April 2018. MATERIALS AND METHODS: Three hundred patients (144 women and 156 men) with cataract undergoing phacoemulsification surgery were recruited in this cross-sectional study. Refraction, keratometry and visual acuity measurement were performed before surgery. Then, a steep-based incision in the cornea was made without stitches. A 3.2 mm corneal incision was made at two supratemporal and temporal sites. The patients were followed-up for one and six months, and one year after surgery monitoring their vision and refraction, and performing keratometric measurements. RESULTS: The mean age of the patients was 65.7±9.54 years (age range, 42-84 years). No major complications were observed. The greatest mean of changes in corneal power was in the supratemporal incision (1.28±0.6). Keratometry had a significant relation with the incision (p.

Heritability of pachymetric indices using Pentacam Scheimflug imaging.

AIM: To investigate the heritability of corneal thickness at the apex, entrance pupil centre, thinnest point, pachymetric progression index (PPI) and maximum Ambrósio relational thickness (ARTmax) using Pentacam. METHODS: The present cross-sectional and population-based study was conducted in two rural districts that were selected randomly. Individuals 5 years and older and data from households where one of the parents and at least one child participated in the study were considered for this analysis. All subjects were examined for visual acuity, refraction, biomicroscopy and, finally, Pentacam imaging. The heritability estimate was used to calculate familial aggregation of pachymetric indices. RESULTS: Of the 3851 selected individuals, 3314 participated in the study. After applying the exclusion criteria, a total of 1383 individuals from 382 households were included in the analysis; of these, 754 (54.52%) were female. The mean age of the subjects was 37.23±19.35 years (from 6 to 93 years). The highest heritability was observed for corneal thickness at the apex (85%), and the lowest was for ARTmax (27.62%). The heritability of other studied parameters, including corneal thickness at the entrance pupil centre, thinnest point and average PPI, was 82.0%, 77.0% and 31.49%, respectively. CONCLUSION: The high heritability of the mentioned pachymetric parameters confirms the high correlation between these phenotypes and genetic factors and calls for genetic and molecular research to find related genes and to understand the aetiology of associated diseases, especially glaucoma and keratoconus.

Preferred Learning Styles among Ophthalmology Residents: An Iranian Sample.

PURPOSE: This study was performed to assess the learning styles of a sample of Iranian residents through Kolb's and VARK questionnaires. METHODS: In this descriptive-analytical study, 45 ophthalmology residents of Mashhad University of Medical Sciences were enrolled. Kolb's and VARK questionnaires were provided, and residents were oriented and guided on how to complete them. RESULTS: Forty-three out of the forty-five ophthalmology residents completed the questionnaire (95.5% response rate). The preferred learning style among ophthalmology residents was assimilative (51.2%), followed by convergent (37.2%), accommodative (7.7%), and divergent (4.7%), based on Kolb's questionnaire. According to the results of the VARK questionnaire, most ophthalmology residents were auditory learners (34.9%), followed by multimodal learners (30.2%). In addition, there was no significant relation between genders, stage of residency, and Kolb's and VARK learning styles (P > 0.05 for all). CONCLUSION: The most preferred learning styles of ophthalmology residents were assimilative and auditory. Considering the dominant learning styles of learners and incorporating various teaching methods are recommended to enhance the learning among residents.

Comparison between Tear Film Osmolar Cocentration and Other Tear Film Function Parameters in Patients with Diabetes Mellitus.

PURPOSE: To evaluate tear film function in patients with diabetes mellitus (DM) using tear film osmolarity (TFO) measurements compared to other tear film function tests. METHODS: DM patients without any history of ocular surface disorder but with potential effects on the tear film were enrolled in this cross-sectional study. Data including dry eye symptoms, duration of DM, stage of diabetic retinopathy and blood hemoglobin A1c levels were recorded. Tear film break-up time (TBUT) and basic tear secretion (Schirmer test) were assessed. TFO was determined using the Tearlab Osmolarity System. The outcome measures were the difference between the mean values of TBUT, basic tear secretion and TFO in both the study and control groups. RESULTS: We recruited 51 DM patients and 20 control subjects with a mean age of 51.2 (range, 21 to 70) and 48.5 (range, 24 to 70) years, respectively. A total of 27 patients (53%) and 11 controls (55%) reported dry eye symptoms (p = 0.668). The mean TBUT was 10.2 ± 4.8 seconds in the study group versus 10.5 ± 2.8 seconds in controls, which was not significantly different (p = 0.747). The mean Schirmer test score was 8.1 ± 4.3 mm in the patients versus 10.1 ± 3.0 mm in the controls (p = 0.069). The mean TFO was 294.1 ± 12.9 mosmol/L in the patients versus 291.4 ± 14.5 mosmol/L in the controls (p = 0.456). It was significantly higher in patients with poor glycemic control determined by hemoglobin A1c > 8% (p = 0.003). TFO had a positive correlation with the duration of DM (p = 0.030) but not with the stage of diabetic retinopathy (p = 0.944). However, TFO showed a significant relationship with dry eye symptoms (p = 0.001). CONCLUSIONS: TFO is impaired in patients with uncontrolled DM and is better correlated with glycemic control and dry eye symptoms than the TBUT and Schirmer tests.

Association of the Myocilin Gene Polymorphism With Primary Open Angle Glaucoma.

Glaucoma is the second cause of irreversible blindness, and the Primary Open Angle Glaucoma (POAG) subtype is the most common type of glaucoma. It has been shown that genetic mutations increase the risk of POAG used for early detection. The aim of the current study was to determine the association between genetic variations of Myocilin (MYOC) gene and susceptibility to POAG in the Iranian population. This case-control study was conducted on patients with POAG, referred to Khatam-al Anbia Eye Hospital, Mashhad, Iran. The control group was selected from healthy patients with a refractive disorder, who had referred to this hospital. After extracting the DNA from the whole blood sample, the Polymerase Chain Reaction-Single-Strand Conformation Polymorphisms (PCR-SSCP) method was used to discriminate variability in sequences in three exons of MYOC gene locus, known as GLC1A. Clinical characteristics of the subjects, comprised of visual acuity, Cup to Disc Ratio (CDR), and Intra-Ocular Pressure (IOP) were statistically compared between the wild and mutant type of the MYOC gene using independent samples t-test, Chi-square, and logistic regression test with SPSS version 15.0 software. P-values of < 0.05 were considered significant. One hundred and forty participants (75.1% males) were studied in two groups of case (n = 70) and control (n = 70). The frequency of mutant alleles in patients and healthy groups was statistically significant (40% versus 11.5%, Odd's Ratio (OR): 5.1, CI 95% for OR: 2.1 to 12.4, P-value < 0.001). Also, the detected mutation in the case group was significantly higher in exon 1 and 3 (15.7% versus 0%, P-value = 0.001, and 11.5% versus 2.8%, P-value = 0.049, respectively). Based on the result of the current study, it seems that the MYOC gene polymorphisms increased the risk of POAG in the Iranian population.

Heritability of Corneal Curvature and Pentacam Topometric Indices: A Population-Based Study.

PURPOSE: To investigate familial aggregation of anterior and posterior corneal curvature, corneal astigmatism, and some corneal topometric indices using the Pentacam. METHODS: Of 3,851 eligible individuals who resided in the selected areas, 2,779 met the conditions for analysis. However, analysis was limited to families whose Pentacam measures were available for at least 2 family members (father or mother and a child), resulting in 1,383 individuals in 382 families. All selected subjects underwent a set of examinations, including refraction, uncorrected and corrected visual acuity measurement, slitlamp biomicroscopy, and Pentacam imaging. Heritability estimation was used to calculate familial aggregation. RESULTS: The results of our study showed a fairly high corneal curvature heritability. The heritability of K2 and K1 in the anterior surface was 58.61% (95% confidence interval [CI], 54.99-62.23) and 55.82% (95% CI, 52.66-58.98), respectively. The heritability of posterior corneal curvature was slightly higher than that of the anterior corneal curvature. The heritability of K2 and K1 in the posterior surface was 63.42% (95% CI, 60.07-66.77) and 59.67% (95% CI, 55.85-63.49), respectively. Investigation of the quantitative topographic corneal indices showed that index of surface variance (ISV), central keratoconus index, and index of vertical asymmetry (IVA) had the highest levels of heritability (81.2% [95% CI, 73.64-88.76], 75.21% [95% CI, 67.19-82.28], and 66.46% [95% CI, 61.99-70.93], respectively). However, keratometric power deviation and index of height asymmetry had the lowest heritability levels (7.48% 95% CI, [4.94-10.02] and 18.31% [95% CI, 16.07-20.55], respectively). CONCLUSION: The familial aggregation and relatively high heritability of the corneal curvature and some keratoconus-related indices, such as ISV and IVA, confirm a high correlation between these phenotypes and genetic factors and warrant further investigation of the genetic mechanisms in keratoconus.

The Association Between the Transforming Growth Factor Beta-1 -509C>T Gene Polymorphism and Primary Open Angle Glaucoma in North Eastern Iran.

BACKGROUND: Glaucoma is a common cause of irreversible blindness. Transforming growth factor beta-1(TGF-ß1) is the main isoform of TGF-ß superfamily in the eye. Overexpression of TGF-ß1 is shown to be related with the glaucoma. Studies have shown that the presence of mutant T allele of TGF-ß1 -509C>T polymorphism (rs1800469) is associated with increased gene expression. So, in present study, association of the TGF-ß1-509C>T gene polymorphism and primary open angle glaucoma (POAG) in patients from north east of Iran was investigated. METHODS: A case-control study was conducted on 112 POAG patients and 112 control participants. TGF-ß1- 509C>T genotyping was done by PCR-restriction fragment length polymorphism (PCR-RFLP) method using Bsu36I restriction enzyme. Moreover, cup to disk ratio(CDR), intraocular pressure (IOP) and visual acuity (VA) were measured. The obtained results were statistically analyzed. RESULTS: The highest frequency of genotype in the control group was related to CC genotype (44.6%), but the heterozygous CT genotype (45.6%) was observed as the highest frequency of genotypes in patient group (P value: 0.022, OR for TT genotype: 2.54 CI95% for OR: 1.22, 5.27). Also, the frequency of the T mutant allele showed a significant difference between case and control groups (P value: 0.005, OR: 1.73 CI95% for OR: 1.18, 2.53). CONCLUSION: In conclusion, a significant association was seen between TGF-ß1 -509C>T gene polymorphism and POAG disease and inheritance of mutant T allele is considered to be a risk factor for glaucoma in patients living in North Eastern part of Iran.

Significant Association and Increased Risk of Primary Open Angle Glaucoma with TGFB2 Rs991967 Gene Polymorphism in North Eastern Iranian Patients.

BACKGROUND: Glaucoma is one of the main causes of irreversible blindness. The most common type of glaucoma is primary open angle glaucoma (POAG). TGF-ß2, the main TGF-ß isoform in the eye, is critical for extracellular matrix production and angiogenesis. Genetic studies have shown that TGF-ß2 gene (TGFB2) polymorphisms affect its expression in the eye. The aim of this study was to investigate the presence of the TGFB2 rs991967 polymorphism in POAG, and the effect of this polymorphism on clinical characteristics in POAG patients. METHODS: This case-control study was conducted on 112 control participants and 112 POAG patients referred to Khatam-Al-Anbia Eye Hospital, Mashhad, Iran. The TGFB2 rs991967 polymorphism was genotyped by the PCR-restriction fragment length polymorphism (PCR-RFLP) method. The genotyping results and clinical findings were analyzed using SPSS version 16. RESULTS: The most common genotype was AA, observed in 54.5% of the patients (P < 0.0001, OR 12.2, CI 95% for OR: 5.25 to 28.31). Moreover, the highest and lowest frequencies of the mutant A allele were seen in the patient and control groups with percentages of 73 and 40%, respectively. This difference was significant (P < 0.0001, OR: 3.9, CI 95% for OR: 2.6 to 5.9). No significant association was seen between the frequencies of the TGFB2 rs991967 polymorphism genotypes and clinical characteristics in POAG patients. CONCLUSION: The TGFB2 rs991967 polymorphism has a direct and significant association with POAG and significantly increases the risk of developing POAG.

Heritability of Anterior Chamber Indices in Rural Population.

OBJECTIVE: To examine the heritability of the anterior chamber depth, angle, and volume as well as the corneal volume and diameter using Pentacam in households living in underserved rural areas of Iran. MATERIALS AND METHODS: This cross-sectional population-based study was conducted in randomly selected households living in 2 rural districts in the south and north. The data of subjects above 5 years and households in which at least 2 members (father or mother and a child) had Pentacam data were analyzed. Each subject underwent a comprehensive ophthalmic examination, with emphasis on the measurement of visual acuity and refraction, biomicroscopy, and Pentacam imaging. Heritability was estimated to investigate familial aggregation of anterior chamber indices, and the effects of age, sex, and living area were controlled for as confounding factors. RESULTS: Of the 3851 selected individuals, 3314 participated in the study. After applying the exclusion criteria, the data of 1383 subjects from 382 households were included in the analysis. The mean age of the participants was 37.23±19.35 years (range, 6 to 93 y). The highest and lowest heritability estimates were related to the anterior chamber angle (72%) and corneal diameter (28%), respectively. The heritability percentages of the anterior chamber depth, anterior chamber volume, and corneal volume were 47%, 39%, and 57%, respectively. CONCLUSIONS: The high heritability of the anterior chamber angle points to a high correlation between this phenotype and genetic factors. Further genetic and molecular investigations are suggested to find the related genes and understand the etiology of glaucoma.

The normal distribution of corneal eccentricity and its determinants in two rural areas of north and south of Iran.

PURPOSE: The aim of this study was to determine the distribution of corneal eccentricity (E-value) in a normal population and to examine related factors. METHODS: In this cross-sectional study, two villages were selected in Iran using multistage cluster sampling. Selected persons were invited to have a comprehensive eye examination. Examinations in each village were performed at a specific location under standard conditions. After testing for vision and refraction and conducting the slit-lamp exam, E-value was measured with Pentacam. RESULTS: Of the 3851 selected individuals, 3314 participated in the study. After applying the exclusion criteria, data from 2610 subjects was used in the analysis for this report. Mean E-value was 0.53 [95% confidence interval (CI): 0.52 to 0.54]. E-value was not significantly different between males and females. Mean E-value reduced with age from 0.60 in subjects aged 6-20 years to 0.47 in subjects older than 70 years. The hyperopic group of participants had significantly lower E-value than myopic and emmetropic ones (P < 0.001). The relationship of E-value with age, gender, and other anterior segment variables and spherical equivalent was examined in a multiple linear regression model. In multiple linear regression model, age (coef = -0.003), spherical equivalent refraction (coef = -0.005), pupil diameter (coef = 0.018), anterior chamber volume (coef = -0.001), and anterior chamber angle (coef = 0.003) significantly correlated with E-value. CONCLUSIONS: The results of this study showed that the cornea in normal populations is prolate, and the degree of prolateness varies by age, such that older age is associated with a less prolate cornea. This study showed that factors such as age and refractive errors and anterior chamber indices influence the E-value.

Distribution of IOP measured with an air puff tonometer in a young population.

PURPOSE: To determine the normal range of intraocular pressure (IOP) in the young and its association with certain corneal parameters using a non-contact device. METHODS: Subjects were selected from students of Mashhad University of Medical Sciences through stratified sampling. All participants had visual acuity testing, corneal imaging, a comprehensive slit-lamp examination by an ophthalmologist, and IOP measurement using a non-contact air-puff tonometer. RESULTS: Of the 1280 invitees, 1073 (83.8%) participated, and 1027 were eligible. Mean IOP was 16.38 mmHg [95% confidence interval (CI): 16.22-16.53] in the total sample, 16.14 mmHg (95% CI: 15.84-16.45) in men, and 16.48 mmHg (95% CI: 16.31-16.66) in women. There was a significant IOP difference between myopes and emmetropes (P = 0.031). Based on the multiple linear regression model, IOP associated directly with age and central corneal thickness (CCT), and inversely with corneal diameter, spherical equivalent (SE), and keratoconus. Based on standardized coefficients of the regression model, CCT and SE had the strongest association with IOP. CONCLUSIONS: In the present study, we demonstrated the IOP distribution in a young population using a non-contact method. CCT and SE were strongly associated with IOP.

High prevalence and familial aggregation of keratoconus in an Iranian rural population: a population-based study.

PURPOSE: The objective of this study was to determine the prevalence of keratoconus and the potential effect of genetic and environmental factors on its prevalence in households living in rural areas of Iran in a large population-based study. METHODS: The present cross-sectional study was performed in two Iranian rural populations. Two rural areas were randomly selected in the southwest and north of Iran. All individuals over one year of age were invited to participate in the study. The study population underwent a thorough eye examination, including visual acuity measurement, refraction, slit lamp biomicroscopy, and Scheimpflug imaging. The diagnosis of keratoconus was made based on Pentacam-specific criteria, tomographic maps, and clinical findings. After detecting keratoconus cases, its prevalence in the study population was reported as a percentage with a 95% confidence interval (CI). For familial aggregation analysis, the odds ratios of keratoconus and its more severe types were calculated in different family relationships (siblings, parents-offspring, spouses) using second order generalised estimating equation. RESULTS: Of the 3851 eligible individuals, 3314 subjects participated in the study. After applying the exclusion criteria, data from 2667 subjects was used in the analysis. The prevalence of keratoconus in the present population was 4% (95% CI: 3-4). The odds of keratoconus were significantly higher in males (OR = 2.30, p = 0.032). To investigate the familial aggregation of keratoconus, we only evaluated families from which at least two members participated in the study. So, 403 families (1452 participants) were evaluated. Our results showed a higher odds ratio for the sibling pairs compare to parent-offspring pairs and as reported, the odds ratio of the spouses was less than 1.0. CONCLUSION: Our findings showed a relatively high prevalence and familial aggregation of keratoconus in rural areas of Iran, independent of age, sex, and place of residence. This aggregation may be due to heredity or the effect of undetermined shared environmental factors.

The prevalence of keratoconus in a young population in Mashhad, Iran.

PURPOSE: To determine the prevalence of keratoconus and some associated factors in the students of Mashhad University of Medical Sciences, Iran. METHOD: In this cross sectional study, multistage cluster sampling was used to select the participants. All participants underwent retinoscopy, slit lamp examination, topography with the TMS-4 and corneal assessment with the Orbscan II. The diagnosis of keratoconus was based on both clinical evidence and the results of corneal imaging. RESULTS: Of 1280 selected students, 1073 agreed to participate in the study, and of those who agreed, 1027 fulfilled the inclusion criteria. 42.5% of the study population was male with a mean age of 26.1 ± 2.3 years. The prevalence of keratoconus was 2.5% (n = 26) (95% confidence interval, CI 1.6-3.5). Eighteen students (69%) had bilateral keratoconus. Imaging of the cornea revealed that 70% of the keratoconics had nipple cones and the remaining had asymmetric bow-tie patterns. The prevalence of keratoconus was not significantly associated with age or gender (p > 0.05). In a multiple logistic regression model, family history (OR = 11.4, 95% CI: 2.5-51.3) and eye rubbing (OR = 6.3, 95% CI: 1.6-24.3) were significantly correlated with keratoconus. CONCLUSIONS: These results taken together with recent studies in the area suggest that keratoconus may have a higher prevalence in the Middle East and Asia than in Western Countries.

Effects of propofol, etomidate, and thiopental on intraocular pressure and hemodynamic responses in phacoemulsification by insertion of laryngeal mask airway.

PURPOSE: To evaluate the effects of propofol, etomidate, and thiopental administered during phacoemulsification (PE) cataract extraction on intraocular pressure (IOP) and hemodynamic responses with insertion of laryngeal mask airway (LMA). METHODS: In a randomized double-blind clinical trial, patients scheduled for PE with general anesthesia were included. Patients were allocated randomly to 3 groups: group 1 (n=34): 0.3 mg/kg etomidate; group 2 (n=33): 2 mg/kg propofol; and group 3 (n=34): 4 mg/kg thiopental. IOP, systolic blood pressure, and heart rate (HR) were measured before induction as a baseline, 2 min after induction (immediately before insertion of LMA), and 1 and 3 min after LMA insertion. Blood pressure (BP) and HR of patients during the surgery were monitored and registered before and after induction and intubation. RESULTS: In 3 groups, IOP decreased significantly after injection of drugs and insertion of LMA in comparison to basic values, although IOP after LMA insertion was more than before LMA insertion. In case of propofol, the changes in IOP between 2 min after induction and the baseline were higher than others, especially thiopental (P=0.031). BP declined remarkably after induction (P<0.001) and rose significantly after LMA insertion in all groups, except in the propofol group. The HR was decreased significantly after induction, except in thiopental. CONCLUSION: Propofol prevented IOP increase after induction compared with other drugs. Decrease in BP and HR after induction and LMA insertion was remarkable. Thiopental seemed to be the best drug for controlling cardiovascular parameters, especially HR, and it also prevents IOP rise.

Effect of cataract type and severity on visual acuity and contrast sensitivity.

PURPOSE: To determine the effect of cataract type and severity in eyes with pure types of age-related lens opacities on visual acuity (VA) and contrast sensitivity in the presence and absence of glare conditions. METHODS: Sixty patients with senile cataracts aged 40 years or older with no other ocular pathologies were evaluated for VA and contrast sensitivity with and without glare. Lens opacities were classified according to the Lens Opacities Classification System (LOCS) III. VA was measured using the Snellen chart. Contrast sensitivity was measured with the Vector Vision CSV-1000E chart in the presence and absence of glare by calculating the area under log contrast sensitivity (log CS) function (AULCSF). RESULTS: Cataracts were posterior subcapsular in 26 eyes, cortical in 19 eyes and nuclear in 15 eyes. VA significantly decreased with increasing cataract severity and there was significant loss of contrast sensitivity at all spatial frequencies with increasing cataract severity. AULCSF significantly decreased with increasing cataract severity in the presence and absence of glare conditions. Contrast sensitivity was significantly reduced at high spatial frequency (18 cpd) in cortical cataracts in the presence of glare in day light and at low spatial frequency (3 cpd) in night light. CONCLUSION: Increased cataract severity is strongly associated with a decrease in both VA and AULCSF. Contrast sensitivity scores may offer additional information over standard VA tests in patients with early age-related cataracts.

Short-term Outcomes of Collagen Crosslinking for Early Keratoconus.

PURPOSE: To assess the efficacy of collagen crosslinking with riboflavin and ultraviolet A (UVA) radiation for treatment of early keratoconus. METHODS: Thirty-one eyes of 22 patients with early keratoconus were included in this study. All patients underwent slit lamp examination and assessment of uncorrected visual acuity (UCVA), best spectacle-corrected visual acuity (BSCVA), intraocular pressure, corneal topography and pachymetry. Collagen crosslinking was performed without epithelial removal. Riboflavin was applied to the cornea every 3 minutes 30 minutes before UVA irradiation and every 5 minutes thereafter. Patients were re-assessed 1, 3, and 6 months after treatment. RESULTS: Postoperatively, UCVA increased by 2 Snellen lines and BSCVA was improved by 1.7 Snellen lines (P < 0.001). Spherical equivalent refractive error was reduced by 0.55 D, and maximum and mean K values were decreased by 0.65 D and 0.51 D respectively (P < 0.05 for all comparisons). Evidence of regression was present in 71% of treated eyes. CONCLUSION: Collagen crosslinking demonstrated significant improvement in vision with reduction in corneal power and spherical equivalent refractive error in eyes with early keratoconus.

Comparison of central corneal thickness measurement using ultrasonic pachymetry, rotating Scheimpflug camera, and scanning-slit topography.

PURPOSE: To evaluate and compare central corneal thickness measurements using rotating Scheimpflug camera, scanning-slit topography, and ultrasound pachymetry in virgin, healthy corneas. DESIGN: Prospective, observational, cross-sectional study. METHODS: Central corneal thickness in 157 healthy eyes of 157 patients without ocular abnormalities other than refractive errors was measured, in a sequential order, once with rotating Scheimpflug camera and scanning-slit topography and 3 times with ultrasound pachymetry as the last part of examination. All measurements were performed by a single experienced examiner. The results from scanning-slit topography are given with and without correction for "acoustic correction factor" of 0.92. RESULTS: The average measurements of central corneal thickness by rotating Scheimpflug imaging, scanning-slit pachymetry, and ultrasound were 537.15 ± 32.98 µm, 542.06 ± 39.04 µm, and 544.07 ± 34.75 µm, respectively. The mean differences between modalities were 6.92 µm between rotating Scheimpflug and ultrasound (P < .0001), 2.01 µm between corrected scanning-slit and ultrasound (P = .204), and 4.91 µm between corrected scanning-slit and rotating Scheimpflug imaging (P = .001). According to Bland-Altman analysis, highest agreement was between ultrasonic and rotating Scheimpflug pachymetry. CONCLUSIONS: In the assessment of normal corneas, rotating Scheimpflug topography measures central corneal thickness values with higher agreement to ultrasound pachymetry.