Topometric and Tomographic Evaluation of Subclinical Keratoconus.

PURPOSE: To investigate the corneal topometric and tomographic findings that can be used in the diagnosis of subclinical keratoconus. METHODS: A retrospective cohort study. The study group was selected from patients with clinically evident keratoconus in one eye and subclinical keratoconus without evident topographic findings in fellow eye. The age-matched control group was selected from patients who were candidates for laser in situ keratomileusis (LASIK) and did not develop ectasia after LASIK surgery at least 1-year follow-up. All subjects underwent topographic, topometric and tomographic (Belin-Ambrósio Enhanced Ectasia Display III) analyses via a Pentacam HR rotating Scheimpflug camera (Oculus, Germany, version 1.20r.98) before LASIK surgery. RESULTS: The study group consisted of 151 patients (69 male and 82 female, mean age of 24.8 ± 7.2 years) and the control group also consisted of 150 patients (70 male and 80 female, mean age of 26.0 ± 6.3 years). There were statistically significant differences in all measured topometric (p˂.05) and tomographic (p˂.001) parameters between the eyes with subclinical keratoconus and those of the control group. In discriminating eyes with subclinical keratoconus from normal eyes, final D showed the highest area under curve value (0.858, sensitivity 85.2%, specificity 66.7%), followed by maximum pachymetric progression index (0.809, sensitivity 81.9%, specificity 69.4%) and average pachymetric progression index (0.796, sensitivity 81.9%, specificity 68.1%) in receiver operating characteristic analysis. CONCLUSION: Topometric and tomographic parameters might be useful for early detection of keratoconus, but the sensitivity and specificity of any parameter are not high enough to be used alone.

Corneal endothelial changes in type 2 diabetes mellitus relative to diabetic retinopathy.

BACKGROUND: To evaluate the morphological features of corneal endothelial cells and their relationship with the stage of retinopathy in diabetes mellitus (DM). METHODS: Patients with type 2 DM and age-matched controls were included in this prospective, cross-sectional study. Patients with diabetic retinopathy (DR) were divided into no-DR, non-proliferative DR and proliferative DR based on the fundus findings. Endothelial measurements were obtained using specular microscopy (Topcon SP-3000P, Japan). Endothelial cell density, average cell area, co-efficient variation of cell area and percentage of hexagonal cells were evaluated. Central corneal thickness (CCT) was measured using an ultrasound pachymeter. Endothelial cell parameters and CCTs of DM and control groups were compared and subgroup analysis of the patients with DM was performed. RESULTS: One hundred and twenty patients (mean age 59.5 ± 8.1 years) were in the DM group, 112 patients (mean age 57.3 ± 7.2 years) were in the control group. Both the endothelial cell density and the hexagonal cell rate were lower, while the CCT was higher in the DM group. There were no significant differences between these two groups in terms of average cell area and co-efficient variation of cell area. Significant differences were detected between endothelial cell density values of subgroups, and endothelial cell density decreased as the stage of the DR increased. The average cell area, co-efficient variation of cell area and CCT measurements were similar across subgroups. Hexagonality values were significantly different between subgroups, with the lowest ratio of hexagonal cells in the proliferative DR group. CONCLUSION: Additional precautions should be taken to reduce the risk of endothelial decompensation prior to intraocular surgery, especially in patients with proliferative DR.

The association between genetic polymorphism of glutathione peroxidase 1 (rs1050450) and keratoconus in a Turkish population / A associação entre o polimorfismo genético da glutationa-peroxidase 1 (rs1050450) e pacientes com ceratocone em uma população turca

ABSTRACT Purpose: To investigate the potential associations between keratoconus and catalase rs1001179, superoxide dismutase 2 rs4880, and glutathione peroxidase 1 rs1050450 gene polymorphisms in a Turkish population. Methods: The study group included 121 unrelated keratoconus patients and 94 unrelated healthy controls. Blood samples (200 ml) were collected from all patients and controls to isolate genomic DNA. Genotyping was performed to identify rs1001179, rs4880, and rs1050450 using real-time polymerase chain reaction (PCR). Genotype and allele frequencies were calculated; their associations with keratoconus risk were assayed, and the association with keratoconus risk and demographic factors was examined. Results: Glutathione peroxidase 1 rs1050450 polymorphism was present in 41% cases compared with 29% controls (OR=1.66; 95% CI=1.11-2.50; p=0.014). No association was observed between catalase rs1001179 and SOD2 rs4880 polymorphisms and keratoconus (for all, p>0.05). Conclusions: This study evaluated possible relationships between rs1050450, rs1001179, and rs4880 polymorphisms and keratoconus susceptibility. We found a possible association between glutathione peroxidase 1 rs1050450 polymorphism and an increased risk of keratoconus. However, the genotype and allele frequencies were identical in the catalase rs1001179 and superoxide dismutase 2 rs4880 polymorphisms. Further studies are needed to analyze the effect of such variations in identifying keratoconus susceptibility.

RESUMO Objetivo: Investigar as possíveis associações entre o ceratocone e os polimorfismos rs1001179 da catalase, rs4880 da superóxido-dismutase 2 e rs1050450 da glutationa-peroxidase 1 rs1050450 em uma população turca. Métodos: O grupo de estudo incluiu 121 pacientes com ceratocone não relacionados e 94 controles saudáveis também sem pa rentesco. Amostra de sangue (200 mL) foram coletadas de todos os pacientes e controle para isolar o DNA genômico. A genotipagem foi realizada para identificar rs1001179, rs4880 e rs1050450 utilizando a reação em cadeia da polimerase (PCR) em tempo real. As frequências de genótipos e alelos foram calculadas, suas associações com o risco de ceratocone foram avaliadas, e a associação com risco de ceratocone e fatores demográficos foi examinada. Resultados: O polimorfismo da glutationa-peroxidase 1 rs1050450 estava presente em 41% dos casos, comparado com 29% dos controles (OR=1,66, IC 95%=1,11-2,50; p=0,014). Não foi observada associação entre o ceratocone e os polimorfismos rs1001179 e SOD2 rs4880 da catalase (para todos, p>0,05). Conclusões: Este estudo avaliou possíveis relações entre os polimorfismos rs1001179, rs4880 e suscetibilidade a cerato cone. Encontramos uma possível associação entre po limorfis mo da glutationa-peroxidase 1 rs1050450 e um risco aumentado de ceratocone. No entanto, o genótipo e as frequências alélicas foram idênticas nos polimorfismos rs1001179 da catalase e superóxido-dismutase 2 rs4880. Mais estudos são necessários para esclarecer o efeito dessas va riações na detecção da sus cetibilidade ao ceratocone.

The association between genetic polymorphism of glutathione peroxidase 1 (rs1050450) and keratoconus in a Turkish population.

PURPOSE: To investigate the potential associations between keratoconus and catalase rs1001179, superoxide dismutase 2 rs4880, and glutathione peroxidase 1 rs1050450 gene polymorphisms in a Turkish population. METHODS: The study group included 121 unrelated keratoconus patients and 94 unrelated healthy controls. Blood samples (200 ml) were collected from all patients and controls to isolate genomic DNA. Genotyping was performed to identify rs1001179, rs4880, and rs1050450 using real-time polymerase chain reaction (PCR). Genotype and allele frequencies were calculated; their associations with keratoconus risk were assayed, and the association with keratoconus risk and demographic factors was examined. RESULTS: Glutathione peroxidase 1 rs1050450 polymorphism was present in 41% cases compared with 29% controls (OR=1.66; 95% CI=1.11-2.50; p=0.014). No association was observed between catalase rs1001179 and SOD2 rs4880 polymorphisms and keratoconus (for all, p>0.05). CONCLUSIONS: This study evaluated possible relationships between rs1050450, rs1001179, and rs4880 polymorphisms and keratoconus susceptibility. We found a possible association between glutathione peroxidase 1 rs1050450 polymorphism and an increased risk of keratoconus. However, the genotype and allele frequencies were identical in the catalase rs1001179 and superoxide dismutase 2 rs4880 polymorphisms. Further studies are needed to analyze the effect of such variations in identifying keratoconus susceptibility.

Evaluation of corneal and lens clarity in unilateral pseudoexfoliation syndrome: a densitometric analysis.

BACKGROUND: Although ageing is the main reason for cataract progression, pseudoexfoliation syndrome (PES) represents an independent additional hazard for the development of nuclear sclerosis and cataract progression. PES can also affect corneal properties. From this perspective, this study aimed to perform a comparison of the corneal and lens densitometry measurements in eyes with PES and age-matched healthy eyes. METHODS: This prospective cross-sectional study included 31 patients with unilateral PES and 40 control participants. The Pentacam HR imaging system was used to evaluate corneal densitometry (12 mm corneal diameter) and lens densitometry measurements of eyes with PES (Group 1), clinically unaffected fellow eyes (Group 2) and healthy eyes (Group 3). RESULTS: Eyes in Group 1 and Group 2 had statistically significantly higher corneal densitometry values for all concentric zones and layers compared with eyes in Group 3 (p < 0.05 for all). However, the results were similar when Group 1 and Group 2 were compared (p > 0.05 for all). The lens densitometry values of zone 1, zone 2 and zone 3, as well as the average lens densitometry measurements, were statistically significantly higher in Groups 1 and 2, compared with Group 3 (p < 0.05 for all). On the other hand, these parameters were similar between Groups 1 and 2 (p > 0.05 for all). Additionally, there was no significant difference between the study and control groups with regard to the maximum lens densitometry measurements (p > 0.05). CONCLUSION: This study revealed that corneal and lens densitometry values of affected and fellow eyes of cases with clinically unilateral PES are significantly higher than those of healthy subjects.

Anterior Segment Changes during Accommodation in Accommodative Esotropia.

PURPOSE: To evaluate the anterior segment biometric parameters of non-accommodative and accommodative refractive accommodative esotropia (RAE). METHODS: Eighty-one eyes of 81 patients were included in this prospective, case-control study. The patients were divided into three groups as follows: the RAE group (n = 31), the hypermetropia group (n = 25), and the emmetropia group (n = 25). Measurements were obtained in the non-accommodative (0.0 diopters) and accommodative status (-5.0 diopters) using a Pentacam HR. The anterior chamber depth (ACD), anterior chamber volume (ACV), pupil diameter (PD), and anterior chamber angle (ACA) were evaluated at all four quadrants. RESULTS: The ACD, ACV and PD values in the RAE group were lower than those of the other groups in both states (p < 0.05). The ACD values were lower in the hypermetropia group than in the emmetropia group for the non-accommodative status (p = 0.024) but were similar for the accommodative status (p = 0.225). PD and ACV values were lower in the hypermetropia group than in the emmetropia group in both states (non-accommodative status, p = 0.011 and p = 0.022; accommodative status, p = 0.026 and p = 0.034, respectively). Changes in ACD, ACV and PD during accommodation (Δ) were not significant in the RAE group but were significant for the other groups (hypermetropia: ΔACD, p = 0.001; ΔACV, p = 0.001; ΔPD, p = 0.002; emmetropia: ΔACD, p < 0.001; ΔACV, p = 0.001; ΔPD, p < 0.001). These changes were significantly lower in the hypermetropia group than in the emmetropia group (ΔACD, p = 0.012; ΔACV, p = 0.031; ΔPD, p = 0.034). CONCLUSIONS: The anterior chamber in RAE patients was shallower and the increase in convexity of the anterior surface or forward movement of the crystalline lens was more limited during accommodation in RAE.

Effect of corneal biomechanical properties on surgically-induced astigmatism and higher-order aberrations after cataract surgery.

PURPOSE:: To investigate the relationship between biomechanical properties of the cornea and postoperative refractive changes in patients with low-level astigmatism after cataract surgery. METHODS:: This prospective study recruited patients undergoing cataract surgery involving 2.8-mm superior incisions. Biomechanical properties of the cornea were evaluated preoperatively using the Ocular Response Analyzer, and corneal profiles were evaluated using a Scheimpflug system (Pentacam HR). Topographic astigmatism, total corneal aberrations (TCA) and higher-order corneal aberrations (HOCA) analyses were performed preoperatively and during 1- and 3-month postoperative exams. The incidences of surgically-induced astigmatism (SIA) and HOCAs were calculated using vector analyses. Associations of the preoperative biomechanical properties of the cornea with SIA and HOCAs were evaluated. RESULTS:: This study included 28 eyes of 28 patients. The preoperative corneal hysteresis (CH) was 8.68 ± 1.86 mmHg, and the corneal resistance factor (CRF) was 8.66 ± 1.61 mmHg. At the 1-month postoperative evaluation, significant changes were observed in HOCAs (p=0.023), TCAs (p=0.05), astigmatism (p=0.02), and trefoil (p=0.033); in contrast, differences in coma (p=0.386) and spherical aberration (SA) were not significant (p=0.947). At the 3-month visit, significant changes were only observed in TCAs (p=0.02) and HOCAs (p=0.012). No relationships between the preoperative corneal hysteresis and corneal resistance factor and postoperative SIA and HOCA were identified, other than a positive correlation between the 3-month postoperative incidence of corneal hysteresis and spherical aberration. CONCLUSIONS:: Despite the observed lack of relationships of preoperative biomechanical properties of the cornea with SIA and postoperative aberrations (except for SA), further studies involving larger patient groups are needed to explore the unexpected refractive deviations after cataract surgery.

Comparison of Results of Accelerated Corneal Cross-Linking With Hypo-Osmolar Riboflavin Solution Performed on Corneas Thicker and Thinner Than 400 µm.

PURPOSE: To evaluate the effect of accelerated corneal cross-linking (CXL) according to corneal thickness in keratoconus. METHODS: Patients undergoing corneal CXL (9 mW/cm(2)) with hypo-osmolar riboflavin solution were included in this study. The patients were divided into 2 groups. Group 1 included patients with corneal thickness below 400 µm (50 eyes from 45 patients), and group 2 included patients with corneal thickness above 400 µm (50 eyes from 47 patients). Visual acuity (VA), refraction, topographic values, and higher-order aberrations were evaluated in the preoperative term and postoperatively at months 1, 3, and 6. RESULTS: The improvements in VA were significant and similar in both groups [0.25/0.19 logMAR, P = 0.130]. In group 1, the rate of decrease in spherical refraction [0.85/0.27 diopters (D), P = 0.012] and maximum keratometry (Kmax, 2.49/0.68 D, P < 0.001) was significantly higher than that in group 2. The cylindrical change was similar (0.43/0.29 D P = 0.173). Corneal thinning was higher in group 2 (25/40.4 µm P < 0.001). Anterior elevation values decreased at higher rates in group 1 (3.73/0.24 µm P < 0.001); neither group showed a significant difference in posterior elevation (-0.14/-0.4 µm P > 0.05). In group 1, all aberration values except trefoil significantly decreased, whereas in group 2 none of the aberrations decreased except the total root mean square. All higher-order aberration values decreased at significantly higher rates in group 1 (P < 0.05). CONCLUSIONS: In thin corneas, accelerated corneal CXL provides better anatomical changes; however, the improvement in VA is similar to that in thick corneas.

Effect of selective laser trabeculoplasty on macular thickness.

BACKGROUND: To investigate the effects of selective laser trabeculoplasty (SLT) on macular thickness change. METHODS: Forty eyes of 40 consecutive patients with uncontrolled primary open-angle glaucoma with medical treatment were included in this prospective study. SLT was performed to the inferior 180°, and macular thickness was measured. Data were collected before SLT, and 1 week and 1 month after SLT. Macular thickness evaluation was performed in five quadrants, the central 1 mm quadrant (fovea = F), the nasal 3 mm quadrant surrounding F (NQ), temporal quadrant, superior quadrant (SQ), and inferior quadrant (IQ). The preoperative and postoperative thicknesses were compared. RESULTS: There was an increase in macular thickness in the NQ, IQ, and SQ on the first week after SLT compared to preoperative measurements. On the other hand, there was no significant increase in the F and temporal quadrant. On the first month after SLT, thickness in the NQ, IQ, and SQ was back to preoperative measurements, and there was no significant change between the preoperative measurements in any quadrant. CONCLUSION: There was no significant increase in macular thickness shortly after SLT in our study.

Morphologic alterations of both the stromal and subbasal nerves in the corneas of patients with diabetes.

PURPOSE: To evaluate the subbasal and the stromal nerves of the corneas of patients with type 2 diabetes with in vivo confocal microscopy and to compare them with those of nondiabetic patients. METHODS: Thirty-five corneas of patients with type 2 diabetes and 24 corneas of age-matched control subjects were included in the study. Patients with diabetes were further classified with respect to the stage of retinopathy. Subbasal and stromal nerve plexus morphology and thickness were evaluated with in vivo confocal microscopy. Subbasal long nerve fiber (LNF) and total nerve branch (NB) densities were calculated. RESULTS: The mean stromal nerve thickness was significantly higher in patients with diabetes (8.99 +/- 2.32 microm) than that of the control subjects (5.69 +/- 1.49 microm; Mann-Whitney U test; P < 0.001). The proportion of curved stromal nerves in patients with diabetes (45.7%) was also higher than that of normal subjects (20.8%; chi(2), P = 0.05). Subbasal LNF and NB densities were found to significantly lower in the corneas of patients with diabetes (28.3 +/- 10.4 and 39.7 +/- 13.2 nerve/mm(2), respectively) than those of the control subjects (34.1 +/- 5.7 and 58.5 +/- 12.4 nerve/mm(2), respectively; Mann-Whitney, P = 0.012 and P < 0.001). In addition, the subbasal nerve plexus of patients with diabetes appeared significantly thicker and more tortuous than those of the control subjects (Mann-Whitney, P = 0.002 and P = 0.001). CONCLUSION: Both stromal and subbasal nerves appear abnormal in the corneas of patients with diabetes. Patients with proliferative diabetic retinopathy show more pronounced nerve alterations than patients who do not have diabetic retinopathy.