مجله چشم پزشکی بینا
سال بیستم شماره 1 (پاییز 1393)

To determine the distribution of intraocular pressure (IOP), central corneal thickness (CCT), and vertical cup-to-disc ratio (VCDR) in a healthy Iranian population. This cross-sectional, epidemiologic study (Yazd Eye Study, YES) was performed on Iranian adults, aged 40 to 80 years, residing in Yazd, Iran between 2010 and 2011. Eligible subjects were selected using cluster random sampling. Each participant underwent an interview and ophthalmologic examination including refraction, measurement of corrected visual acuity, pachymetry, slit-lamp examination, Goldmann applanation tonometry, binocular optic disc evaluation, fundus photography and visual field. Out of 2,320 eligible individuals, 2,098 subjects (response rate of 90.4%) participated in the study. Of which, 2,262 normal eyes of 1,159 subjects were selected for evaluation. Mean age was 53.1±9.6 years. Mean values for IOP, CCT, and VCDR were 14.2±2.5 mmHg, 543±35 μm, and 0.32±0.14, respectively. Multiple regression analysis showed that IOP had a significant correlation with age, CCT, diabetes mellitus, spherical equivalent refractive error, and smoking. The distribution of IOP, CCT, and VCDR in YES was different from other studies conducted in different geographical regions; it seems advisable to employ a geographical approach for interpretation of normal variables.

To study the distribution of ocular higher-order aberrations (HOAs) and mesopic pupil size in individuals screened for refractive surgery. Ocular HOAs and mesopic pupil size were studied in 2458 eyes of 1240 patients with myopia, simple myopic astigmatism and compound myopic astigmatism and 215 eyes of 110 patients with hyperopia, simple hyperopic astigmatism and compound hyperopic astigmatism using the Zywave aberrometer (Busch& Lomb). All patients had correctable refractive errors without a history of refractive surgery or underlying diseases. Root-mean-square values of HOAs, total spherical aberration, and total coma aberration and mesopic pupil size were analyzed. Ocular HOAs were measured across a ≥ 6.0 mm pupil. Mean values of HOAs, total spherical aberration and total coma aberration in the myopic group were 0.369±0.233 μm, 0.133±0.112 μm and 0.330±0.188 μm, respectively. The corresponding values in the hyperopic group were 0.418±0.214 μm, 0.202±0.209 μm and 0.343±0.201 μm, respectively. The hyperopes showed greater total HOAs (P<0.01) and total spherical aberration (P<0.01) as compared to the myopes. In agematched analysis, only the amount of total spherical aberration was higher in the hyperopic group (P=0.05). Mesopic pupil size was significantly larger in the myopic group than in the hyperopic group (P=0.05). Significant levels of HOAs were found in both groups which are important for planning refractive surgeries. There were significantly higher levels of total spherical aberration in hyperopes compared to myopes. Mesopic pupil size was larger in the latter group.

To compare clinical outcomes following penetrating keratoplasty (PK) versus deep anterior lamellar keratoplasty (DALK) for keratoconic patients with vernal keratoconjunctivitis (VKC). In this retrospective comparative study, the records of 69 keratoconic eyes with VKC that underwent PK (n=43, group 1) or DALK (n=26, group 2) were compiled. Postoperative best-corrected visual acuity (BCVA), refractive error, complications and graft clarity rate were compared between the groups. Mean follow-up period was 42.1±21.7 months in group 1 and 34.9±21.1 months in group 2 (P=0.18). The mean postoperative BCVA was 0.15±0.09 logMAR in group 1 and 0.20±0.15 logMAR in group 2 (P=0.08), with a BCVA of20/40 in 95.2% and 88.5% of the eyes, respectively (P=0.31). Problems in the epithelia were encountered in 7.0% and 42.3% of the eyes in groups 1 and 2, respectively (P=0.001). Suture complications, including stitch abscesses (16.3% versus 53.8%, respectively; P=0.001) and suture tract vascularization (2.3% and 34.6%, respectively; P<0.001), were more frequently observed in group 2. At the 31-month follow-up examination, the rejection-free graft survival rates were 50.0% in group 1 and 33.3% in group 2, with mean durations of 33.0 and 32.1 months, respectively (P=0.89). At the final follow-up examination, all grafts in group 1 and 96.2% of grafts in group 2 remained clear (P=0.75). The clinical outcomes of PK and DALK in eyes with keratoconus and VKC are comparable. However, because certain complications, such as epithelial problems and suture-related complications are more common following DALK, closer monitoring is necessary in these cases.

To evaluate the influence of donor characteristics (age, death-to-preservation time, preservation-tosurgery time, graft rating, and endothelial cell features) on clinical outcomes following deep anterior lamellar keratoplasty (DALK) in patients with keratoconus. In this retrospective study, 290 consecutive keratoconic eyes underwent DALK using donor corneas of different qualities, ranging from fair to excellent. A multivariate regression analysis was used to assess the correlation between donor characteristics and postoperative outcomes. Mean donor and recipient ages were 33.4±13.1 and 27.7±8.0 years, respectively. Mean follow-up period was 38.2±20.2 months. The presence of epithelial defects on postoperative day 1 had a significant correlation with donor epithelial sloughing (R= 0.26, P< 0.001), preservation-to-surgery time (R= 0.21, P= 0.001), and graft rating (R= -0.17, P= 0.004). Graft stromal edema on postoperative day 1 was significantly correlated with donor epithelial sloughing (R= 0.31, P< 0.001), preservation-to-surgery time (R= 0.24, P< 0.001), and graft rating (R= -0.28, P< 0.001). Suture-related complications, graft rejection episodes, graft clarity, visual acuity, and refractive outcomes at the final follow-up examination were found to have no correlation with any donor factors. The donor features had no influence on visual and refractive outcomes and complications.

To determine the prevalence and to describe the demographic pattern of congenital cataract surgery performed at a referral hospital in Iran during four consecutive years with respect to sex inequality in receiving eye care. All children aged 15 years or less who had undergone congenital cataract surgery between 2006 and 2009 in Labbafinejad Medical Center were enrolled in this cross-sectional study. Data were retrieved from the electronic medical records of the hospital admission data bank (Fox PR 6.2. Clipper 5.2) using the ICD-10 coding system. The prevalence of cataract surgery, age and sex proportion were the main outcome measures. Overall, 314 eyes of 259 patients with congenital cataract including 14 eyes of 115 girls (45.2%) and 172 eyes of 144 boys (54.8%) were operated on during the study period; 55 (17.5%) of which had received cataract surgery in the second eye. Mean age at the time of operation was 2.9±2.7 and 3.5±3.2 years in girls and boys, respectively (P= 0.62). The procedures were performed before the age of 1 and 5 years in 33.2% and 75% of the cases, respectively. The operation of the second eye was performed significantly later in girls as compared to the boys (4.2±3.3 vs. 2.6±1.7 years, respectively, P=0.012). During the study period, the rate of operation for congenital/infantile cataract was higher in boys by about 10% as compared to girls. Age at the time of operation for the second eye which comprised 17.5% of total surgeries was significantly different between two genders. Overall, one third and two thirds of surgeries were performed under the age of 1 and 5 years, respectively.

To evaluate the outcomes of traumatic canalicular laceration repair using Masterka silicone tube. This interventional case series included 25 patients with traumatic canalicular laceration who underwent canalicular repair with Masterka tube. The patients were followed at least for 6 months. At last visit, anatomic and functional successes were assessed by diagnostic probing and asking the patients about tearing, respectively. Data corresponding to demographic features, surgical outcomes, and tube-related complications were recorded and analyzed. Mean patient age was 27.7±20.0 (range, 1.5-75) years. Nineteen (76%) patients were male and 10 had a history of sharp trauma. The lower canalicule was involved in 16 patients. Masterka tube was removed 12.43±1.72 (range, 10 to 16) weeks after the surgery. Premature tube loss occurred in patients. Anatomic and functional success rate was 84% and 100%, respectively. Canalicular laceration repair with Masterka tube is a safe and effective method with a low rate of complications, and according to the authors’ experience, is a fast and simple technique.

To develop a computational model for predicting the fluid production and flow, and intraocular pressure (IOP) following glaucoma surgery. To help elucidate the interplay of physical factors controlling the distribution and absorption of aqueous humor in sub-conjunctival tissue, and tissue remodeling, a computational model is developed to predict the fluid production in the eye and removal via the trabecular/uveoscleral pathways, and the surgical pathway. This surgical pathway is then linked to a porous medium computational model of a fluid bleb positioned within the sub-conjunctival tissue. The computational analysis is centered on typical functioning bleb geometry found in a human eye following glaucoma surgery. A parametric study is conducted to study the changes in fluid absorption by the sub-conjunctival blood vessels, changes in hydraulic conductivity due to scarring, and changes in bleb size and shape, and the eye outflow facility. The model was found to be compatible with clinical observations in a number of key ways, specifically the variation of IOP, bleb size and shape and correlation between sites of predicted maximum interstitial fluid pressure and key features observed in blebs. Scar tissue reduces the ability of a bleb to control IOP. An increase in hydraulic conductivity lowers IOP. By changing the height and width of the functioning bleb, IOP and tissue pressure could be compared in the context of bleb size. There is an optimum bleb size and shape, which would avoid excessive scar formation but keep IOP in an acceptable range. the small, thick wall blebs are likely to be ineffective at allowing fluid to move into and be absorbed by tissue. These results suggest that small blebs expose tissue to high pressures, particularly directly above the bleb, inducing an ischemic tissue remodeling response, a reduction of hydraulic conductivity and an elevation of IOP. On the other hand, large blebs are less likely to undergo this remodeling process but may lead to hypotonic eyes. This model should contribute to a more complete explanation of the physical processes behind successful bleb characteristics and provide a new basis for clinically grading blebs.

To compare Freiburg new method with static contrast sensitivity of “MetroVision” system. Fourty emmetropic volunteers aged 18-35 (mean, 21.7±0.4) years and corrected visual acuity of 20/20 or better participated in this study. The participants had no systemic disease, ocular or neurological problems, and received no systemic medication. An informed consent was obtained from all participants. Contrast sensitivity was measured at spatial frequencies of 1, 5 and 15 cycles per degree (cpd) using Freiburg and MetroVision. The agreement between the two methods was evaluated using Bland Altman agreement, relevant maps and correlation methods. Mean contrast sensitivity measured with Freiberg and the MetroVision methods were 22.2±1.3 and 19.4±1.9 dB at frequency of 1 cpd, 22.7±0.7 and 20.7±2.4 dB at frequency of 5 cpd, and 20.5±2.5 and 13.3±3.5 dB at frequency of 15 cpd, respectively. The correlation coefficients of the differences between these two methods with average measurements by the two methods were r= -0.35 (P= 0.001), r= -0.86 (P= 0.000) and r= -0.34 (P=0.002) at frequencies of 1, 5 and 15 cpd, respectively. Freiburg method overestimates contrast sensitivity as compared to MetroVision technique. This overestimation is more remarkable at higher spatial frequencies and lower contrast sensitivities.

Trabeculectomy is the most common procedure performed in glaucoma patients to reduce intraocular pressure for a long-time period. This intervention can cause alterations in axial length (0.1 0.9 mm), anterior chamber depth (0.11±0.22 mm), and keratometry readings (1.07±1.14 diopter). These changes may linger for more than one year and may negatively affect the precision of intraocular lens power calculation for cataract surgery. Measures such as using non-contact biometry methods and postponing cataract surgery until the acceptable stability of biometric changes after trabeculectomy is achieved can reduce these calculation errors. In this systematic review, all the relevant articles published in PubMed between 1977 and 2013 were analyzed.