Ibrahim Toprak

Effects of corneal collagen crosslinking on corneal topographic indices in patients with keratoconus.

Objectives: To evaluate the effects of corneal crosslinking (CXL) on corneal topographic indices in patients with progressive keratoconus using Scheimpflug imaging system. Methods: This retrospective study comprised 59 eyes of 47 patients who underwent CXL treatment for confirmed progressive keratoconus. Changes in corrected distance visual acuity (CDVA, logMAR equivalent), maximum keratometry (K), and corneal topographic indices included index of surface variance (ISV), index of vertical asymmetry, keratoconus index, center keratoconus index (CKI), index of height asymmetry (IHA), index of height decentration, and minimum radius of curvature (Rmin) were analyzed at 1-year follow-up. Correlations between topographic indices and visual acuity were sought. Results: The study included 59 eyes of 47 patients with progressive keratoconus. The mean CDVA (P<0.001), maximum K (P<0.001), ISV, Rmin, and CKI (P =0.013, P < 0.001, respectively) significantly improved after CXL treatment. Moreover, we found a significant negative correlation between the change in IHA value and the improvement in CDVA (r = −0.351; P = 0.006). Conclusions: In patients with progressive keratoconus, cornea becomes more optically regular after CXL treatment. Changes in topographic indices might be valuable to follow-up the normalization of keratoconic cornea during the postoperative course and superior–inferior height symmetry seems to be associated with visual improvement.

A combination of topographic and pachymetric parameters in keratoconus diagnosis

PURPOSE To evaluate the utility of topographic and pachymetric parameters of Scheimpflug system in keratoconus diagnosis. METHODS This study included 183 eyes of 183 patients with keratoconus (keratoconus group) and 131 eyes of 131 age and sex-matched healthy subjects (control group). Mean keratometry (K, front), topographic astigmatism, pupil-center pachymetry, apical pachymetry, thinnest pachymetry (TP), corneal volume and maximum K (Kmax) were obtained from the Scheimpflug imaging system. A receiver operating characteristic (ROC) analysis was performed and area under the curve (AUC) was calculated to determine the diagnostic ability of each parameter in eyes with ≤ stage 3, ≤ stage 2 and stage 1 keratoconus based on the Amsler-Krumeich grading system. RESULTS The Kmax and TP showed the highest individual performance (with sensitivity-specificity of 92.9-92.4% and 89.6-93.3%, respectively) in diagnosis of keratoconus. The AUCs and sensitivity-specificity values for the Kmax/TP and Kmax(2)/TP were calculated to improve the diagnostic performance. As expected, sensitivity-specificity values significantly increased by using Kmax/TP (97.3-94.7% at the level ≥0.08) and Kmax(2)/TP (99.5-95.7% at the level ≥4.1) in discrimination of keratoconic eyes from normals. Moreover, Kmax(2)/TP had very high sensitivity (>99%) and specificity (>94%) in diagnosis of stage 1 and stage 2 keratoconus. CONCLUSIONS Although Kmax and TP appear to have high diagnostic ability in keratoconus, the use of either single parameter in isolation might be unsatisfactory in differential diagnosis. Therefore, the Kmax(2)/TP ratio has been introduced, which reflects major characteristics of keratoconus and might be used as an important criterion in keratoconus diagnosis.

Scheimpflug parameters after corneal collagen crosslinking for keratoconus

Purpose To assess the effects of corneal collagen crosslinking (CXL) on Scheimpflug imaging system parameters in patients with progressive keratoconus. Methods Forty-seven eyes of 47 patients who underwent CXL treatment (CXL group) for progressive keratoconus and 26 eyes of 26 nontreated patients with keratoconus (control group) were included in this retrospective controlled study. Changes in corrected distance visual acuity (CDVA, logMAR equivalent), maximum K (keratometry), corneal volume (CV), corneal thickness, and anterior chamber parameters including anterior chamber depth (ACD), anterior chamber volume (ACV), and anterior chamber angle (ACA) were analyzed at 6 months follow-up. Results The mean CDVA improved (p<0.001); maximum K, CV, and pachymetry measurements significantly decreased after CXL treatment in patients with progressive keratoconus (p = 0.001, p<0.001, respectively). However, in the control group, CDVA, maximum K, CV, and pachymetry measurements remained unchanged at 6 months follow-up (p>0.05). The anterior chamber parameters (ACD, ACV, and ACA) did not show significant changes between baseline and 6 months in CXL and control groups (p>0.05). Conclusions In patients with progressive keratoconus, CXL treatment is effective in improving visual acuity and maximum keratometry. Although the treatment might cause corneal thinning and volume loss, anterior chamber parameters seem not to be affected during the postoperative course.

Diagnostic Consistency and Relation Between Optical Coherence Tomography and Standard Automated Perimetry in Primary Open-Angle Glaucoma

Abstract Purpose: To assess diagnostic consistency and relation between spectral-domain optical coherence tomography (SD-OCT) and standard automated perimetry (SAP) in patients with primary open-angle glaucoma (POAG). Methods: This retrospective study comprised 51 eyes of 51 patients with a confirmed diagnosis of POAG. The qualitative and quantitative SD-OCT parameters (retinal nerve fiber layer thicknesses [RNFL; average, superior, inferior, nasal and temporal], RNFL symmetry, rim area, disc area, average and vertical cup/disc [C/D] ratio and cup volume) were compared with parameters of SAP (mean deviation, pattern standard deviation, visual field index, and glaucoma hemifield test reports). Results: Fifty-one eyes of 51 patients with POAG were recruited. Twenty-nine eyes (56.9%) had consistent RNFL and visual field (VF) damage. However, nine patients (17.6%) showed isolated RNFL damage on SD-OCT and 13 patients (25.5%) had abnormal VF test with normal RNFL. In patients with VF defect, age, average C/D ratio, vertical C/D ratio, and cup volume were significantly higher and rim area was lower when compared to those of the patients with normal VF. In addition to these parameters, worsening in average, superior, inferior, and temporal RNFL thicknesses and RNFL symmetry was significantly associated with consistent SD-OCT and SAP outcomes. Conclusions: In routine practice, patients with POAG can be manifested with inconsistent reports between SD-OCT and SAP. An older age, higher C/D ratio, larger cup volume, and lower rim area on SD-OCT appears to be associated with detectable VF damage. Moreover, additional worsening in RNFL parameters might reinforce diagnostic consistency between SD-OCT and SAP.

Impaired photoreceptor inner segment ellipsoid layer reflectivity in mild diabetic retinopathy.

OBJECTIVE To determine alterations in retinal pigment epithelium (RPE), photoreceptor inner segment ellipsoid layer (ISel), and external limiting membrane (ELM) reflectivities using optical coherence tomography (OCT) image analysis in patients with mild nonproliferative diabetic retinopathy (NPDR). DESIGN Retrospective, single-centre, controlled clinical study. PARTICIPANTS The study cohort included 42 eyes of 42 patients with mild NPDR (NPDR group) and 40 eyes of 40 healthy subjects (control group). Eyes with moderate and severe NPDR, proliferative DR, macular edema, and other macular pathologies were excluded. METHODS The reflectivities of RPE, ISel, and ELM were calculated using a medical image-processing software based on greyscale OCT images. The differences in the reflectivity values between the NPDR and control groups were analyzed. RESULTS The NPDR group comprised 22 males and 20 females (with a mean age of 61.3 ± 6.5 years), and the control group consisted of 14 males and 26 females (with a mean age of 63.0 ± 4.1 years) (p > 0.05). The ISel had significantly lower reflectivity (both absolute and relative) in eyes with mild NPDR compared with that of the control eyes (p < 0.001), whereas the reflectivities of RPE and ELM did not differ between the 2 groups (p = 0.126, p = 0.053 respectively). CONCLUSIONS Although previous ex vivo studies reported photoreceptor degeneration in diabetic retinopathy, this is the first clinical study to investigate retinal layer reflectivities in NPDR using OCT. In eyes with mild NPDR, ISel seems to have lower reflectivity, and this finding might indicate early photoreceptor degeneration in diabetic retinopathy pathogenesis.

Purtscher's Retinopathy: A Case Report

A 22-year-old male patient who had multiple upper extremity fractures and head trauma secondary to motorcycle accident was referred to our clinic a week after trauma for bilateral visual loss. Patient underwent a detailed ophthalmological examination including fundus fluorescein angiography, and he was diagnosed as Purtschers retinopathy (PR). Visual acuity at baseline was counting fingers at 20 cm OD, and 1 meter OS. Patient received pulse steroid for 3 days which is followed by oral steroid with decreasing dosage for 11 days. Visual acuity at last control visit (5 months after trauma) was 0.1 OD, and 1.0 OS. Improvement in vision in our case may be spontaneous or secondary to steroid therapy. Since no proven effective treatment is currently available for PR, we believe that pulse steroid should be a potential option in these cases.