Cirous Dehghani

Prevalence of refractive errors among schoolchildren in Shiraz, Iran.

Purpose:  To determine the prevalence of refractive errors in Shiraz schoolchildren by age and gender.

The Prevalence of Anisometropia, Amblyopia and Strabismus in Schoolchildren of Shiraz, Iran

Purpose: To determine the prevalence of amblyopia, anisometropia, and strabismus in schoolchildren of Shiraz, Iran. Materials and Methods: A random cluster sampling was used in a cross-sectional study on schoolchildren in Shiraz. Cycloplegic refraction was performed in elementary and middle school children and high school students had non-cylcoplegic refraction. Uncorrected visual acuity (UCVA) and best corrected visual acuity (BCVA) were recorded for each participant. Anisometropia was defined as spherical equivalent (SE) refraction difference 1.00D or more between two eyes. Amblyopia was distinguished as a reduction of BCVA to 20/30 or less in one eye or 2-line interocular optotype acuity differences in the absence of pathological causes. Cover test was performed for investigating of strabismus. Results: Mean age of 2638 schoolchildren was 12.5 years (response rate = 86.06%). Prevalence of anisometropia was 2.31% (95% confidence interval [CI], 1.45 to 3.16). 2.29% of schoolchildren (95% CI, 1.46 to 3.14) were amblyopic. The prevalence of amblyopia in boys and girls was 2.32% and 2.26%, respectively (p = 0.945). Anisometropic amblyopia was found in 58.1% of the amblyopic subjects. The strabismus prevalence was 2.02% (95% CI, 1.18 to 2.85). The prevalence of exotropia and esotropia was 1.30% and 0.59%, respectively. Conclusions: Results of this study showed that the prevalence of anisometropia, amblyopia, and strabismus are in the mid range. The etiology of amblyopia was often refractive, mostly astigmatic, and non-strabismic. Exotropia prevalence increased with age and was the most common strabismus type.

Natural history of corneal nerve morphology in mild neuropathy associated with type 1 diabetes: development of a potential measure of diabetic peripheral neuropathy

PURPOSE To investigate longitudinal changes of subbasal nerve plexus (SNP) morphology and its relationship with conventional measures of neuropathy in individuals with diabetes. METHODS A cohort of 147 individuals with type 1 diabetes and 60 age-balanced controls underwent detailed assessment of clinical and metabolic factors, neurologic deficits, quantitative sensory testing, nerve conduction studies, and corneal confocal microscopy at baseline and four subsequent annual visits. The SNP parameters included corneal nerve fiber density (CNFD), branch density (CNBD), and fiber length (CNFL), and were quantified using a fully automated algorithm. Linear mixed models were fitted to examine the changes in corneal nerve parameters over time. RESULTS At baseline, 27% of the participants had mild diabetic neuropathy. All SNP parameters were significantly lower in the neuropathy group compared with controls (P < 0.05). Overall, 89% of participants examined at baseline also completed the final visit. There was no clinically significant change to health and metabolic parameters and neuropathy measures from baseline to the final visit. Linear mixed model revealed a significant linear decline of CNFD (annual change rate, -0.9 nerve/mm(2), P = 0.01) in the neuropathy group compared with controls, which was associated with age (β = -0.06, P = 0.04) and duration of diabetes (β = -0.08, P = 0.03). In the neuropathy group, absolute changes of CNBD and CNFL showed moderate correlations with peroneal conduction velocity and cold sensation threshold, respectively (r, 0.38 and 0.40, P < 0.05). CONCLUSIONS This study demonstrates dynamic small fiber damage at the SNP, thus providing justification for our ongoing efforts to establish corneal nerve morphology as an appropriate adjunct to conventional measures of diabetic peripheral neuropathy.

Morphometric stability of the corneal subbasal nerve plexus in healthy individuals: a 3-year longitudinal study using corneal confocal microscopy.

PURPOSE We examined the age-dependent alterations and longitudinal course of subbasal nerve plexus (SNP) morphology in healthy individuals. METHODS Laser-scanning corneal confocal microscopy, ocular screening, and health and metabolic assessment were performed on 64 healthy participants at baseline and at 12-month intervals for 3 years. At each annual visit, eight central corneal images of the SNP were selected and analyzed using a fully-automated analysis system to quantify corneal nerve fiber length (CNFL). Two linear mixed model approaches were fitted to examine the relationship between age and CNFL, and the longitudinal changes of CNFL over three years. RESULTS At baseline, mean age was 51.9 ± 14.7 years. The cohort was sex balanced (χ(2) = 0.56, P = 0.45). Age (t = 1.6, P = 0.12) and CNFL (t = -0.50, P = 0.62) did not differ between sexes. A total of 52 participants completed the 36-month visit and 49 participants completed all visits. Age had a significant effect on CNFL (F[1,33] = 5.67, P = 0.02) with a linear decrease of 0.05 mm/mm(2) in CNFL per one year increase in age. No significant change in CNFL was observed over the 36-month period (F[1,55] = 0.69, P = 0.41). CONCLUSIONS The CNFL showed a stable course over a 36-month period in healthy individuals, although there was a slight linear reduction in CNFL with age. The findings of this study have implications for understanding the time-course of the effect of pathology and surgical or therapeutic interventions on the morphology of the SNP, and serves to confirm the suitability of CNFL as a screening/monitoring marker for peripheral neuropathies.

Utility of assessing nerve morphology in central cornea versus whorl area for diagnosing diabetic peripheral neuropathy

Purpose: To compare small nerve fiber damage in the central cornea and whorl area in participants with diabetic peripheral neuropathy (DPN) and to examine the accuracy of evaluating these 2 anatomical sites for the diagnosis of DPN. Methods: A cohort of 187 participants (107 with type 1 diabetes and 80 controls) was enrolled. The neuropathy disability score (NDS) was used for the identification of DPN. The corneal nerve fiber length at the central cornea (CNFLcenter) and whorl (CNFLwhorl) was quantified using corneal confocal microscopy and a fully automated morphometric technique and compared according to the DPN status. Receiver operating characteristic analyses were used to compare the accuracy of the 2 corneal locations for the diagnosis of DPN. Results: CNFLcenter and CNFLwhorl were able to differentiate all 3 groups (diabetic participants with and without DPN and controls) (P < 0.001). There was a weak but significant linear relationship for CNFLcenter and CNFLwhorl versus NDS (P < 0.001); however, the corneal location × NDS interaction was not statistically significant (P = 0.17). The area under the receiver operating characteristic curve was similar for CNFLcenter and CNFLwhorl (0.76 and 0.77, respectively, P = 0.98). The sensitivity and specificity of the cutoff points were 0.9 and 0.5 for CNFLcenter and 0.8 and 0.6 for CNFLwhorl. Conclusions: Small nerve fiber pathology is comparable at the central and whorl anatomical sites of the cornea. Quantification of CNFL from the corneal center is as accurate as CNFL quantification of the whorl area for the diagnosis of DPN.

Risk factors associated with corneal nerve alteration in type 1 diabetes in the absence of neuropathy: a longitudinal in vivo corneal confocal microscopy study

Purpose: The aim of this study was to determine alterations to the corneal subbasal nerve plexus (SNP) over 4 years using in vivo corneal confocal microscopy in participants with type 1 diabetes and to identify significant risk factors associated with these alterations. Methods: A cohort of 108 individuals with type 1 diabetes and no evidence of peripheral neuropathy at enrollment underwent laser-scanning in vivo corneal confocal microscopy, ocular screening, and health and metabolic assessment at baseline, and the examinations continued for 4 subsequent annual visits. At each annual visit, 8 central corneal images of the SNP were selected and analyzed to quantify corneal nerve fiber density, corneal nerve branch density and corneal nerve fiber length. Linear mixed model approaches were fitted to examine the relationship between risk factors and corneal nerve parameters. Results: A total of 96 participants completed the final visit and 91 participants completed all visits. No significant relationships were found between corneal nerve parameters and time, sex, duration of diabetes, smoking, alcohol consumption, blood pressure, or body mass index. However, corneal nerve fiber density was negatively associated with glycated hemoglobin (&bgr; = −0.76, P < 0.01) and age (&bgr; = −0.13, P < 0.01) and positively related to high-density lipids (&bgr; = 2.01, P = 0.03). Higher glycated hemoglobin (&bgr; = −1.58, P = 0.04) and age (&bgr; = −0.23, P < 0.01) also negatively impacted corneal nerve branch density. Corneal nerve fiber length was only affected by higher age (&bgr; = −0.06, P < 0.01). Conclusions: Glycemic control, high-density lipid, and age have significant effects on SNP structure. These findings highlight the importance of diabetic management to prevent corneal nerve damage and the capability of in vivo corneal confocal microscopy for monitoring subclinical alterations in the corneal SNP in diabetes.

Development of a novel technique to measure corneal nerve migration rate

Purpose: We have developed a novel technique to measure in vivo corneal nerve migration. Methods: Wide-field montages of the subbasal corneal nerve plexus were generated at baseline and after 3 weeks. The 2 montages were manually examined side by side to identify a referent landmark in the inferior whorl region and 20 additional nerve landmarks throughout each montage. A software program was developed to measure nerve migration by quantifying the movement of the nerve landmarks relative to the inferior whorl landmark over the 3-week period. To illustrate the utility of this technique, nerve migration was measured in 2 individuals with diabetes (one with and the other without neuropathy) and a healthy control participant. Results: The average nerve migration rate was calculated to be 18.4, 49.9, and 41.5 &mgr;m/wk for the diabetic individuals with and without neuropathy and the control participant, respectively. The number of landmarks for tracking nerve migration in the participants was 26, 21, and 20, and they were at an average distance of 1500, 1940, and 1461 &mgr;m, from the whorl, respectively. The rate of migration depended on the distance from the whorl; hence, linear equations were generated for each subject for comparison. Conclusions: This novel imaging technique allows rapid measurement of in vivo corneal nerve migration. The results indicate that diabetic neuropathy may be associated with reduced nerve migration; however, because of the high level of manual input required in this technique and the apparent complex characteristics of corneal nerve migration, repeatability and characterization studies are needed.

Presence of Peripheral Neuropathy Is Associated With Progressive Thinning of Retinal Nerve Fiber Layer in Type 1 Diabetes

Purpose Reduced retinal nerve fiber layer (RNFL) thickness has been demonstrated in patients with diabetic peripheral neuropathy (DPN) in cross-sectional studies. This prospective study defines longitudinal alterations to the RNFL thickness in individuals with type 1 diabetes without (DPN-ve) and with (DPN+ve) DPN and in relation to risk factors for nerve damage. Methods A cohort of 105 individuals with type 1 diabetes (20% DPN+ve) with predominantly mild or no retinopathy and no previous retinal photocoagulation underwent spectral-domain optical coherence tomography (SD-OCT) at baseline, 2 years, and 4 years. SD-OCT scans were acquired at 3.45-mm diameter around the optic nerve head and the overall RNFL and RNFL in the nasal, superior, temporal, and inferior quadrants were quantified. By including serial quantified RNFL parameters, linear mixed models were applied to assess the change in RNFL thickness over time and to explore the associations with other clinical variables. Results There was a significant decline in the overall RNFL thickness (-0.7 μm/y, P = 0.02) and RNFL in the superior quadrant (-1.9 μm/y, P < 0.01) in the DPN+ve group compared with DPN-ve group. The overall RNFL thickness and RNFL in the superior and nasal quadrants were inversely associated with age (β = -0.29, -0.41, and -0.29, respectively; P ≤ 0.02). Sex, retinopathy, diabetes duration, hemoglobin A1c, lipid profile, blood pressure, cigarette use, alcohol consumption, and body mass index did not show any significant effects (P > 0.05). Conclusions Individuals with DPN showed a progressive RNFL thinning overall and in the superior quadrant, which was more pronounced in older individuals. There may be common pathways for retinal and peripheral neurodegeneration that are independent of conventional DPN risk factors.

Effect of ocular hypotony secondary to cyclodialysis cleft on corneal topography.

Purpose: To report the changes in corneal topography in 2 cases of ocular hypotony induced by cyclodialysis cleft after blunt trauma, which were successfully treated by argon laser photocoagulation. Methods: For both patients, a full ophthalmic clinical examination and corneal topography were performed before and after argon laser cleft closure. Results: In the first case, the corneal topography showed 3.81-D astigmatism at 96°, which was reduced to 1.1 D at 124° 1 week after treatment and 0.66 D at 122° at 3 weeks after treatment. In the second case, the corneal astigmatism was 3.91 D at 104°, which decreased to 1.44 D at 104° and 0.35 D at 118° at 1 week and 4 months after treatment, respectively. Conclusions: In both cases, the with-the-rule astigmatism reduced significantly after successful closure of the cleft and an increase in intraocular pressure.

Ophthalmic and clinical factors that predict four-year development and worsening of diabetic retinopathy in type 1 diabetes

AIMS To investigate the role of ophthalmic imaging markers - namely retinal thickness measures and corneal nerve morphology - in predicting four-year development and worsening of diabetic retinopathy (DR) in type 1 diabetes (T1DM). METHODS 126 eyes of 126 participants with T1DM were examined at baseline and after four years. Diabetic retinopathy (DR) was graded using the Early Treatment Diabetic Retinopathy Study scale. HbA1c, nephropathy, neuropathy, cardiovascular factors, and retinal thickness using optical coherence tomography (OCT) and corneal nerve fiber length (CNFL) using corneal confocal microscopy at baseline were assessed by univariate and step-wise multiple logistic regression, and their diagnostic capabilities for single and combined measures. RESULTS Four-year development of DR was 19% (13 of 68 without DR at baseline). Worsening of DR was seen in 43% (25 of 58 with DR at baseline). When adjusted for potential confounders, a lower CNFL (AUC=0.637, p=0.040, 64% sensitivity and 64% specificity at 14.9mm/mm2 cut-off), higher triglycerides (AUC=0.669, p=0.012, 64% sensitivity, 62% specificity at 0.85mmol/L) and an elevated vibration threshold (AUC=0.708, p=0.002, 96% sensitivity, 40% specificity at 3.55Hz) were significant predictors for four-year worsening of DR. CONCLUSIONS Reduced CNFL, elevated vibration perception threshold and higher triglycerides can predict future worsening of DR.