Changes in Limbal Optical Coherence Tomography Angiography Outcomes in Patients With Overnight Contact Lens Wear.

OBJECTIVES: To evaluate the perilimbal vasculature of patients who wear contact lenses (CLs) overnight with optical coherence tomography angiography (OCTA) and compare the results with healthy population. METHODS: Forty-two patients were included in this observational study. The OCTA imaging was performed in the temporal quadrant of the perilimbal region using a swept-source optical coherence tomography system (Triton DRI-OCT; Topcon Corporation, Tokyo, Japan). The assessments were made in two depths: starting from the conjunctival epithelium to 200 µm scleral depth and the scleral depth between 200 and 1,000 µm. The vessel density, vessel length density, vessel diameter index, and fractal dimension were the main outcomes and compared between overnight CL users and healthy population. RESULTS: Twenty-two patients who have been using CLs overnight for at least 3 months and 20 healthy individuals were included in the study. The vessel density at the superficial layer was significantly higher in the CL group compared with the control group (P<0.001). Vessel diameter index, vessel length density, and fractal dimension at the superficial layer did not differ between the groups (P>0.05 for all). There was no difference in the vessel density, vessel diameter index, vessel length density, and fractal dimension in the deep layer between the groups (P>0.05 for all). CONCLUSIONS: Patients who use CL overnight exhibit increased vessel density in the superficial layers of the perilimbal region, which may suggest new vessel formation in the conjunctiva. Anterior segment OCTA may be useful to evaluate the initial changes in limbal vasculature in CL users.

EVALUATION OF RETINAL VESSEL DIAMETERS IN EYES WITH ACTIVE CENTRAL SEROUS CHORIORETINOPATHY.

PURPOSE: To compare the retinal vessel diameters of healthy eyes and active central serous chorioretinopathy (CSC) eyes, and to evaluate possible effect of retinal vessel diameter alterations on the pathogenesis of CSC. METHODS: This retrospective study included 39 patients with CSC and 34 healthy individuals. Spectralis optical coherence tomography + HRA with an infrared reflectance image were used to evaluate structure of retinal vessels in the circular region around the optic disc. For each eye, vertical inner and outer diameters of the four major arteries and veins were measured using infrared reflectance images, and vessel wall thicknesses were also calculated based on inner and outer diameters. RESULTS: The 304 vessels of the 39 active CSC eyes and 266 vessels of the 34 healthy eyes were used in the analyses. The mean venous wall thickness in active CSC eyes was significantly thicker than that in healthy eyes (40.0 ± 4.9 vs. 33.5 ± 4.1 µm, P = 0.001), whereas the mean venous inner diameter in active CSC eyes was significantly narrower (52.5 ± 9.7 vs. 61.3 ± 8.1 µm, P = 0.001). Also, the mean venous outer diameter was wider in CSC eyes, albeit not significantly (131.1 ± 7.0 vs. 128.5 ± 8.4 µm, P = 0.074). CONCLUSION: Our results suggest that the alterations of retinal venous diameters may play a potential role in the pathogenesis of CSC in addition to alterations in choroidal thickness.

Assessing posterior ocular structures in ß-thalassemia minor.

PURPOSE: The aim of this study was to investigate the effect of ß-thalassemia minor on choroidal, macular, and peripapillary retinal nerve fiber layer thickness. METHODS: To form the sample, we recruited 40 patients with ß-thalassemia minor and 44 healthy participants. We used spectral-domain optical coherence tomography to take all measurements of ocular thickness, as well as measured intraocular pressure, axial length, and central corneal thickness. We later analyzed correlations of hemoglobin levels with ocular parameters. RESULTS: A statistically significant difference emerged between patients with ß-thalassemia minor and the healthy controls in terms of mean values of subfoveal, nasal, and temporal choroidal thickness (p = 0.001, p = 0.016, and p = 0.010, respectively). Except for central macular thickness, differences in paracentral macular thicknesses between the groups were also significant (superior: p < 0.001, inferior: p = 0.007, temporal: p = 0.001, and nasal: p = 0.005). Also, no statistically significant differences were noted for retinal nerve fiber layer thickness between two groups. CONCLUSION: Mean values of subfoveal, nasal, temporal choroidal, and macular thickness for the four quadrants were significantly lower in patients with ß-thalassemia minor than in healthy controls.

Corneal Sublayers Thickness in Patients With Mitral Valve Prolapse.

OBJECTIVES: The aim of this study was to compare the thickness of each corneal sublayer in patients with mitral valve prolapse (MVP) and healthy individuals. METHODS: A total of 38 eyes from 38 patients with MVP and 34 eyes from 34 age- and sex-matched healthy individuals were included in this study. The thickness of the corneal epithelium, Bowman layer, stroma, and Descemet membrane-endothelium complex were measured on the central cornea (i.e., corneal apex) and both the inferior and superior halves of the cornea with anterior segment module of spectral domain optical coherence tomography. RESULTS: No statistically significant differences emerged between the study and control groups in terms of Bowman layer thickness in the central cornea and the cornea's superior half (P=0.092 and P=0.128, respectively). However, in the inferior half of the cornea, Bowman layer thickness among patients with MVP was 11.95±2.34 µm (range 7-16 µm) and in the control group was 13.03±1.62 µm (range 10-16 µm), which made for a statistically significant difference (P=0.025). CONCLUSIONS: Our study revealed thinning of Bowman layer in the inferior half of the cornea in patients with MVP.

The Effect of Age on Dexamethasone Intravitreal Implant (Ozurdex®) Response in Macular Edema Secondary to Branch Retinal Vein Occlusion.

PURPOSE: To investigate the effect of age on dexamethasone intravitreal implant (Ozurdex®) response in macular edema secondary to branch retinal vein occlusion (BRVO). METHODS: Seventy-three eyes of 73 patients with macular edema secondary to BRVO were recruited in the study. The patients in the study were divided into the following four groups according to their ages: group 1 (<60 years), group 2 (60-69 years), group 3 (70-79 years), and group 4 (≥80 years). Single-dose Ozurdex injection was applied to all patients. The effectiveness of Ozurdex treatment on macular edema is evaluated via optical coherence tomography (OCT) according to the age groups. RESULTS: Two months after Ozurdex injection, mean reduction of central retinal thickness in groups 1, 2, 3, and 4 were -466.4 ± 149.6, -379.7 ± 238.7, -280.1 ± 233.0, and -180.5 ± 81.4 µm, respectively. This reduction of central retinal thickness decreased with aging (p = 0.001). Also, ages of patients were negatively correlated with the mean reduction of central retinal thickness for the whole study group (r = -0.439, p < 0.001). CONCLUSION: Our study revealed that the effectiveness of Ozurdex treatment decreases with aging.

Comparison of Ganglion Cell and Retinal Nerve Fiber Layer Thickness in Pigment Dispersion Syndrome, Pigmentary Glaucoma, and Healthy Subjects with Spectral-domain OCT.

PURPOSE: To evaluate the ganglion cell complex (GCC) and retinal nerve fiber layer (RNFL) thickness in pigment dispersion syndrome (PDS) and pigmentary glaucoma (PG) with RTVue spectral domain optical coherence tomography (SD-OCT). METHODS: A total of 102 subjects were enrolled: 29 with PDS, 18 with PG, and 55 normal subjects. Full ophthalmic examination including visual field analysis was performed. SD-OCT was used to analyze GCC superior, GCC inferior, and average RNFL thickness. To compare the discrimination capabilities, the areas under the receiver operating characteristic curves were assessed. RESULTS: Superior GCC, inferior GCC, and RNFL thickness values of patients with PG were statistically signicantly lower than those of patients with PDS (p < 0.001) and healthy individuals (p < 0.001 for all). No statistically significant difference was found between PDS and normal subjects in same parameters (p > 0.05). CONCLUSIONS: The SD-OCT-derived GCC and RNFL thickness parameters can be useful to discriminate PG from both PDS and normal subjects.

The assessment of choroidal thickness with spectral-domain optical coherence tomography during Valsalva maneuver.

PURPOSE: The purpose of the study was to evaluate the effect of Valsalva maneuver (VM) on choroidal thickness. METHODS: All the volunteers underwent a detailed opthalmic examination. Third-generation Spectralis OCT device (software version 5.6.3.0; Spectralis OCT, Heidelberg Engineering, Dossenheim, Germany) was used for assessment. Subfoveal and perifoveal CT of all volunteers were measured by using EDI-OCT technology. Perifoveal CT was measured 1500 µm nasally and 1500 µm temporally apart from the foveal center. The measurements were repeated while volunteers were performing VM. RESULTS: Sixty-four eyes of 32 healthy volunteers were assessed. The volunteers were aged 29-50. The mean age was 32.8 ± 6.6 years. Choroidal thickness measurements differed with statistical significance between resting position and VMin all regions (p < 0.001). While mean subfoveal CT was 350.64 ± 87.73 µm during resting position, it was 369.95 ± 90.12 µm during VM (p < 0.001). While mean nasal CT was 292.14 ± 81.67 µm during resting position, it was 305.46 ± 85.80 µm during VM (p < 0.001). While mean temporal CT was 325.93 ± 80.91 µm during resting position, it was 343.21 ± 81.53 µm during VM (p < 0.001). CONCLUSIONS: We found statistically significant increase in choroidal thickness during the VM in healthy volunteers. This result might be important for future studies researching autoregulation of choroidal and retinal blood flow in physiologic and pathologic conditions. Also, our study is noteworthy to stand out the errors in EDI-OCT measurements caused by unintentional breath holding of patients.

Evaluations of Corneas in Eyes with Isolated Iris Coloboma.

PURPOSE: We aimed to evaluate the differences in the corneas of eyes with isolated iris coloboma. METHODS: This study was designed as a prospective study. Among patients who applied to our hospital within the last 3-year period, those with isolated iris coloboma in one eye and a completely normal contralateral eye were included in the study. In addition to a complete ophthalmologic examination, all patients were scanned by Pentacam Scheimpflug camera in the dark, and a corneal endothelium cell count was taken using a Topcon Specular Microscope. Data entered using SPSS software were then evaluated by paired t-test; p < 0.05 value was considered statistically significant. RESULTS: Nine patients, seven men and two women, with a mean age of 35.77 ± 22.50 (range 8-60) years, were included in the study. In comparison to normal eyes, the colobomatous eyes were statistically found to have lower keratometry values in diopters (43.82 ± 2.17, 44.46 ± 1.86; p = 0.040), a greater negative asphericity (Q value) (-0.38 ± 0.07, -0.22 ± 0.20; p = 0.042), increased corneal thickness (569.78 ± 25.42, 537.33 ± 27.36; p < 0.001), decreased anterior chamber depth (2.50 ± 0.32, 2.81 ± 0.50; p = 0.005), a shallower angle (30.51 ± 10.68, 35.29 ± 9.99; p = 0.057), higher best-fit sphere (BFS) values of the anterior and posterior corneal surfaces (7.88 ± 0.39, 7.67 ± 0.37; p = 0.001; 6.40 ± 0.26, 6.23 ± 0.19; p = 0.006), larger pupil diameter (3.48 ± 0.49, 2.80 ± 0.34; p = 0.001), smaller horizontal corneal diameter (HCD) (11.06 ± 0.42; 11.26 ± 0.45; p = 0.009), and higher value of endothelial cell density (ECD) (3161 ± 431; 2923 ± 590; p = 0.031). CONCLUSION: We have determined that a number of factors such as keratometry values, particularly of the corneal endothelium, are different from those of normal eyes. These differences should be taken into account in the follow-up and treatment of eyes with iris coloboma.

Does Valsalva Maneuver Affect Corneal Morphology in Eyes With Keratoconus?

OBJECTIVES: The aim of this study was to investigate the effect of the Valsalva maneuver on corneal morphology and anterior chamber parameters in patients with keratoconus. METHODS: A total of 39 eyes from 39 patients with keratoconus and 41 eyes from 41 age-matched and gender-matched healthy individuals were included in this cross-sectional study. Measurements of corneal front keratometry values (K-flat, K-steep, and K-max), central corneal thickness, corneal apex thickness, thinnest corneal thickness, corneal volume, anterior chamber volume (ACV), anterior chamber depth (ACD), and iridocorneal angle (ICA) were performed with a Pentacam Scheimpflug camera (Oculus, Germany) before and during the Valsalva maneuver. Changes in the anterior segment parameters from baseline and during the Valsalva maneuver and the differences in parameters between the keratoconus group and the control group were analyzed. A P value less than 0.05 was accepted as statistically significant. RESULTS: In the patients with keratoconus, the Valsalva maneuver did not have any significant influence on the corneal parameters (P>0.05). However, ACV, ACD, and ICA decreased markedly during the Valsalva maneuver (P=0.006, P=0.048, and P=0.025, respectively). Changes caused by the Valsalva maneuver were similar for all parameters when compared with those in healthy individuals (P>0.05). CONCLUSIONS: During corneal topography imaging, the Valsalva maneuver observed in patients with keratoconus does not typically cause any significant change in corneal morphology.

Short-term effects of intravitreal dexamethasone implant (OZURDEX®) on choroidal thickness in patients with naive branch retinal vein occlusion.

PURPOSE: The objective of this study was to evaluate subfoveal choroidal thickness (SFCT) using enhanced depth imaging optical coherence tomography (EDI-OCT) in patients with naïve branch retinal vein occlusion (BRVO) before and after intravitreal dexamethasone implant (Ozurdex®) injection. METHODS: Thirty-nine patients with unilateral BRVO and 35 healthy subjects were included in this prospective study. Choroidal thickness was evaluated by EDI-OCT at baseline and 1 month after dexamethasone implant. RESULTS: The mean SFCT measured in 39 patients with BRVO was 299.41 ± 55.86 µm, significantly greater than that in contralateral eyes (283.76 ± 57.44 µm; p=0.009) and control eyes (276.14 ± 39.06 µm; p=0.044). The mean SFCT after the treatment was 279.64 ± 50.96 µm, significantly thinner than that before intravitreal dexamethasone therapy (p=0.004). CONCLUSIONS: SFCT in treatment-naive BRVO eyes was significantly greater than that in contralateral eyes and healthy eyes and decreased significantly after intravitreal dexamethasone implantation.

Short-term effects of intravitreal dexamethasone implant (OZURDEX®) on choroidal thickness in patients with naive branch retinal vein occlusion / Os efeitos a curto prazo do implante de dexametasona intravítrea (OZURDEX®) na espessura da coroide em pacientes com oclusão primária de ramo da veia central da retina

ABSTRACT Purpose: The objective of this study was to evaluate subfoveal choroidal thickness (SFCT) using enhanced depth imaging optical coherence tomography (EDI-OCT) in patients with naïve branch retinal vein occlusion (BRVO) before and after intravitreal dexamethasone implant (Ozurdex®) injection. Methods: Thirty-nine patients with unilateral BRVO and 35 healthy subjects were included in this prospective study. Choroidal thickness was evaluated by EDI-OCT at baseline and 1 month after dexamethasone implant. Results: The mean SFCT measured in 39 patients with BRVO was 299.41 ± 55.86 µm, significantly greater than that in contralateral eyes (283.76 ± 57.44 µm; p=0.009) and control eyes (276.14 ± 39.06 µm; p=0.044). The mean SFCT after the treatment was 279.64 ± 50.96 µm, significantly thinner than that before intravitreal dexamethasone therapy (p=0.004). Conclusions: SFCT in treatment-naive BRVO eyes was significantly greater than that in contralateral eyes and healthy eyes and decreased significantly after intravitreal dexamethasone implantation.

RESUMO Objetivo: O objetivo deste estudo foi avaliar a espessura da coróide (SFCT) usando imagens de tomografia de coerência óptica com profundidade aprimorada (EDI-OCT) no tratamento de pacientes com oclusão primária de ramo da veia central da retina (BRVO) antes e após o implante de dexametasona intravítrea (Ozurdex®). Métodos: Trinta e nove pacientes com BRVO unilateral e 35 indivíduos saudáveis foram incluídos neste estudo prospectivo. Espessura da coróide foi avaliada por EDI-OCT na antes e um mês após o tratamento. Resultados: A média da SFCT medida em 39 pacientes com BRVO foi 299,41 ± 55,86 µm, o que foi significativamente maior do que a dos olhos contralaterias (283,76 ± 57,44 µm) e dos olhos controle (276,14 ± 39,06 µm) (p=0,009 e p=0,044, respectivamente). A média da SFCT após o tratamento foi 279,64 ± 50,96 µm, o que foi significativamente menor do que antes do mesmo (p=0,004). Conclusões: A SFCT do tratamento de olhos com BRVO primária foi significativamente maior do que a dos olhos contralaterais e dos olhos saudáveis, e diminuiu significativamente após o implante intravítreo de dexametasona.

Choroidal changes in pre-eclampsia during pregnancy and the postpartum period: comparison with healthy pregnancy.

PURPOSE: To investigate subfoveal choroidal thickness (SFCT) in patients with pre-eclampsia using enhanced depth imaging optical coherence tomography (EDI-OCT). METHODS: A sample of 73 pregnant women was studied over 28 weeks of gestation. The sample was divided into two groups: one comprising pre-eclamptic pregnant women (n=32), and the other comprising healthy pregnant women (n=41). The SFCT was determined for all patients using EDI-OCT during pregnancy and at the third month of the postpartum period. RESULTS: The SFCTs in pre-eclamptic pregnant women were 351.97 ± 22.44 and 332.28 ± 20.32 µm during the pregnancy and postpartum periods (p<0.001), respectively, whereas these values in healthy pregnant women were 389.73 ± 49.64 and 329.78 ± 22.36 µm (p<0.001), respectively. During pregnancy SFCT in pre-eclamptic pregnant women was significantly thinner than that in healthy pregnant women (p<0.001). However, there was no statistically significant difference during the postpartum period (p=0.623). CONCLUSIONS: The results suggest that SFCT is significantly decreased in pre-eclamptic pregnant women than in healthy pregnant women, despite no statistically significant difference in SFCT existing between the groups during the postpartum period.

Systemic endothelial function in cases with wet-type age-related macular degeneration.

BACKGROUND: Choroidal endothelial dysfunction plays key role in wet-type age-related macular degeneration (AMD). Peripheral vascular endothelial function is not known in wet AMD. OBJECTIVE: We aimed to analyze peripheral vascular endothelial function in cases with wet-type age-related macular degeneration by measuring flow-mediated dilatation (FMD). MATERIALS AND METHODS: The study included 20 cases with wet AMD (Group 1, mean age 65.9 ± 7.2 years) and 24 healthy individuals (Group 2, mean age 62.0 ± 11.9 years). In all cases, a cardiologist assessed the responses of endothelial function by measuring the FMD following brachial artery occlusion. RESULTS: Mean FMD, an indicator of endothelial function was found to be 6.4 ± 2.7 % in Group 1 and 15.6 ± 7.3 % in Group 2 (p < 0.001). There was no significant difference between patient and control groups regarding age, sex, total cholesterol, LDL cholesterol, HDL cholesterol, triglyceride, ESR and CRP. CONCLUSION: Reduced FMD is present in patients with wet AMD, suggesting that impaired peripheral endothelial function may be involved in its pathogenesis.

Modified Y-splitting Procedure for the Treatment of Duane Retraction Syndrome.

OBJECTIVES: To present the outcomes of modified lateral rectus Y-splitting combined with either unilateral or bilateral horizontal rectus recession in Duane Retraction Syndrome (DRS) with significant upshoot or downshoot. MA­TE­RI­ALS AND MET­HODS: A total of 12 patients including 10 patients with Type I DRS and 2 with Type III DRS underwent modified Y-splitting surgery. Amount of additional recessions varied with the degree of preoperative deviation by intraoperative adjustable suture technique. Preoperatively 3 patients had esotropia (ET), 6 had exotropia (XT), and 3 patients had orthotropia. The mean preoperative deviation was 19.3 prism diopters (PD) (range, 18-20 PD) in ET patients and 19.2 PD (range, 16-20 PD) in XT patients. RE­SULTS: Postoperatively, all patients had significant correction in horizontal deviation and aligned within 4 PD of orthotropia, and no patients exhibited abnormal head posture. Co-contraction and globe retraction were markedly reduced and abnormal ocular vertical movement disappeared or significantly decreased in all cases. No patients experienced recurrence of ocular motility disorders in the mean 26-month (range, 13-66 months) follow-up period. CONCLUSION: Modified Y-splitting surgery combined with co-contracting horizontal muscle recession technique seems to be a safe and effective treatment in DRS.

The impact of migraine on posterior ocular structures.

Purpose. To investigate the thickness of the retinal nerve fiber layer (RNFL) and choroid in patients who have migraines in comparison to healthy controls. Methods. This study included 76 eyes and patients in the migraine group, 36 with aura (MWA group) and 40 without (MWoA group), and 38 eyes as control subjects. The RNFL and macular thicknesses were analysed with standard OCT protocol while choroidal thickness was analysed with EDI protocol in all subjects. Choroidal thickness was measured at the fovea, 1500 µm nasal and 1500 µm temporal to the fovea in a horizontal section. Results. The mean RNFL thickness for nasal and nasal inferior sectors was significantly thinner (P ≤ 0.018) in the migraineurs' eyes than in those of the controls, as was the mean choroid thickness at the fovea and measured points (P < 0.0001). However, the mean macular thickness was not significantly different between the groups. Conclusions. This study suggests that migraine leads to a reduction in the peripapillary RNFL thickness and to thinning in choroidal structures. These findings can be explained by a chronic ischemic insult related to migraine pathogenic mechanisms and these findings are considered supportive of the relationship between glaucoma and migraine.

Early surgical results of a 23-gauge trocar combined with a one-directional valve system in primary and secondary pars plana vitrectomy.

BACKGROUND/AIM: To elucidate the early surgical advantages of a 23-gauge trocar combined with a one-directional valve system in transconjunctival pars plana vitrectomies. MATERIALS AND METHODS: Early surgical results of 432 eyes of 432 patients (190 female and 242 male) who underwent 23-gauge (23G) transconjunctival sutureless vitrectomies (TSV) were evaluated. Sixty-three patients out of 432 underwent a second operation, 29 of them underwent silicone oil extraction, and 34 had phacoemulsification surgery with the help of vitreous infusion. If any sign of leakage was observed after the withdrawal of the cannulae, a suture was applied at the conjunctiva-scleral opening site. RESULTS: A total of 21 (4.8%) patients in the first operation and 7 (11.1%) cases in the second operation needed suture in at least 1 sclerotomy site. No one had intraoperative hypotony. On postoperative day 1, 37 initial surgery patients and 3 second TSV patients had hypotony; all of them resolved spontaneously 1 week after surgery. No one developed choroidal effusions or detachment. Intraocular pressure spikes more than 22 mmHg in day 1 occurred in 18 eyes after initial TSV; 6 of them had gas and 4 eyes had silicone tamponade. CONCLUSION: 23G TSV is an effective and safe procedure for both first vitreoretinal surgery and second intraocular surgeries in eyes that had TSV previously.

Short-term effects of intravitreal triamcinolone acetonide injection on ocular blood flow evaluated with color Doppler ultrasonography.

AIM: To evaluate the changes in ocular blood flow with color Doppler ultrasonography (CDU) after intravitreal triamcinolone acetonide (IVTA) injection. METHODS: A total of 46 patients who underwent IVTA (4 mg/0.1 mL) injection for diabetic macular edema (DME) (n=22), central retinal vein occlusion (CRVO) (n=12) and choroidal neovascular membrane (CNVM) (n=12) were included in the study. Peak systolic velocity (PSV), end diastolic velocity (EDV) and resistivity index (RI) were measured from the ophthalmic artery (OA), the central retinal artery (CRA) and the posterior ciliary artery (PCA) of each patient with CDU before, at the end of the first week and at the end of the first month following IVTA injection. RESULTS: In the DME group, PSV of OA at the first of the first month (mean±SD) (37.48±10.87 cm/s) increased compared to pre-injection value (31.39±10.84 cm/s) (P=0.048). There was a statistically significant decrease (P=0.049) in PSV of CRA at the end of the first month (7.97±2.67 cm/s) compared to the pre-injection (9.47±3.37 cm/s). There was not any statistically significant difference on the other parameters in the DME group. Also, there was not any statistically significant difference on the ocular blood flow values in the CRVO and CNVM groups. CONCLUSION: We observed that 4 mg/0.1 mL IVTA increased PSV of OA and decreased PSV of CRA in DME patients and did not have any effect on ocular blood flow values of CRVO and CNVM patients.

Comparison of ocular response analyzer parameters in primary open angle glaucoma and exfoliative glaucoma patients.

AIM: We sought to identify differences in the following measures of the ocular response analyser (ORA) between primary open angle glaucoma (POAG) and exfoliative glaucoma (EXG) patients: Corneal hysteresis (CH), corneal resistance factor (CRF), corneal-compensated intraocular pressure (IOPcc) and Goldmann-correlated intraocular pressure (IOPg). We also sought to relate these ORA measures with central corneal thickness (CCT). MATERIALS AND METHODS: This cross-sectional study was conducted on a total of 162 individuals (46 EXG patients, 66 POAG patients and 50 healthy subjects without any ocular and systemic disease). ORA measurements were performed, and a minimum of three readings were obtained from each test subject. Groups were compared according to their ORA parameters. RESULTS: The mean CH levels of the EXG, POAG and healthy subjects were 7.6 ± 2.1, 9.1 ± 1.9 and 9.6 ± 1.7 mmHg, respectively. CH was significantly lower in the EXG patients compared to the other groups (P < 0.001).The mean CRF levels of the EXG, POAG and healthy subjects were 9.0 ± 2.0, 10.1 ± 1.7 and 9.8 ± 1.8mmHg, respectively. CRF levels in the eyes of the EXG patients were significantly lower compared to those of either the POAG patients (P = 0.005) or the healthy subjects (P = 0.03), but there was no significant difference in CRF levels between the POAG patients and the healthy subjects (P = 0.59). There was a significant positive correlation between CH and CCT in the EXG patients and healthy subjects (P < 0.001), but this correlation was not present in the POAG patients (P = 0.70). CONCLUSIONS: In this study, CH and CRF were found to be significantly reduced in the eyes of EXG patients compared to both the POAG patients and healthy subjects. Reduced CH in EXG patients might result in decreased support of peripapillary scleral structure and increased damage to the optic nerve during IOP increase.