Koray Gumus

Ocular blood flow in patients with obstructive sleep apnea syndrome (OSAS).

BackgroundSleep-related disorders are among the important risk factors for neurovascular diseases. Obstructive sleep apnea syndrome (OSAS) is characterized by snoring, excessive daytime sleepiness, and insomnia. Our aim was to investigate the presence of glaucoma in patients with OSAS and to reveal vascular pathology related to the pathogenesis of glaucoma in those patients.Patients and methodsThe study included 31 patients with OSAS and 25 control subjects. Orbital Doppler ultrasonography was used to determine the resistivity index (RI) in the ophthalmic artery and central retinal artery. All patients and controls underwent perimetric examination.ResultsThe prevalence of glaucoma in the group of patients with OSAS was 12.9% (4/31); all of these 4 patients with glaucoma were in the “severe” OSAS group. No statistically significant difference was found between ophthalmic artery resistivity index (OARI), central retinal artery resistivity index (CRARI), and intraocular pressure (IOP) between patients and controls (p > 0.05). There was a positive correlation between OARI and mean defect (MD), CRARI and MD, and CRARI and loss variance (LV) values (p < 0.05). There was also a positive correlation between IOP and the apnea-hypopnea index (AHI) (p = 0.001).ConclusionsIn patients with OSAS, a high prevalence was found and it is interesting to note that all of the four glaucoma patients were in the severe OSAS group. The positive correlation observed between IOP and AHI suggests that increased IOP values may reflect the severity of OSAS. The positive correlation between OARI and MD and also between CRARI and MD as well as LV suggests that visual field defects may be due to optic nerve perfusion defects and these field defects also increase as the RI increases.

Tear Meniscus Dimensions in Tear Dysfunction and Their Correlation With Clinical Parameters

PURPOSE To evaluate relationships between tear meniscus dimensions and parameters of ocular surface disease in a variety of tear dysfunction conditions. DESIGN Single-institution prospective observational study. METHODS This study from the Baylor College of Medicine included 128 eyes of 64 subjects. Cross-sectional lower tear meniscus height and tear meniscus area were measured using optical coherence tomography and were compared with tear break-up time (TBUT), corneal staining, conjunctival staining, and an irritation symptom questionnaire (Ocular Surface Disease Index). Study groups included meibomian gland disease (MGD), aqueous tear deficiency (ATD), Sjögren syndrome, non-Sjögren syndrome ATD, and control subjects. Statistical analyses were performed using the Pearson correlation and Students t test. RESULTS When compared with mean tear meniscus height in controls (345 μm), mean tear meniscus height was lower in all tear dysfunction (234 μm; P = .0057), ATD (210 μm; P = .0016), and Sjögren syndrome groups (171 μm; P = .0054). For tear meniscus height ≤210 μm, relative risk ratio for developing corneal staining ≥10 was 4.65. Tear meniscus height correlated with corneal staining for all subjects (R = -0.32; P = .0008), MGD (R = +0.40; P = .059), and ATD (R = -0.36; P = .04). Tear meniscus area showed similar trends in MGD (R = +0.55; P = .006) and ATD (R = -0.40; P = .018). Tear meniscus height correlated with TBUT for all subjects (R = +0.39; P < .0001) and ATD (R = +0.37; P = .018). CONCLUSIONS In tear dysfunction conditions, lower tear volume correlates with worse corneal epithelial disease in ATD and Sjögren syndrome, conditions with lacrimal gland dysfunction. In contrast, higher tear volume is associated with corneal epithelial disease in MGD. These findings may improve the ability to identify patients at risk for corneal epithelial disease.

Anterior Segment Optical Coherence Tomography: A Diagnostic Instrument for Conjunctivochalasis

PURPOSE To evaluate cross-sectional areas of conjunctivochalasis and tear meniscus using Fourier-Domain RTVue-100 optical coherence tomography (OCT) before and after conjunctival cauterization and to evaluate inter- and intraobserver reliability. DESIGN Prospective, nonrandomized, consecutive case study. METHODS A total of 12 eyes of 7 patients with conjunctivochalasis (aged 56 to 87) were evaluated. After topical anesthesia, conjunctival cauterization was performed on the inferior bulbar conjunctiva. All patients underwent anterior segment OCT (AS-OCT) imaging prior to and 4 weeks after the procedure. Cross-sectional tear meniscus and conjunctivochalasis areas at 3 locations (nasal, center, and temporal areas) were measured in all patients. RESULTS Nonsignificant increases (P = .177) in cross-sectional tear meniscus area as a whole (3 locations combined) were observed following cauterization. Cross-sectional conjunctivochalasis area measurements significantly decreased in all 3 locations after cauterization (P < .001). Mean cross-sectional conjunctivochalasis area decreased from 0.247 ± 0.24 mm(2) to 0.054 ± 0.79 mm(2). For 2 measurements of cross-sectional tear meniscus area by examiner 1, intraclass correlation coefficients ranged from 0.998 to 0.999. Among 2 examiners, Cronbachs alpha reliability coefficients were as high as 0.993 and 0.997 before and after conjunctival cauterization. Regarding the cross-sectional conjunctivochalasis area measurements, intraclass correlation coefficient values were similar to those of the cross-sectional tear meniscus area, but Cronbachs alpha reliability coefficients were slightly less. CONCLUSIONS This study indicates the AS-OCT is a useful and reproducible instrument to measure the cross-sectional area of conjunctiva prolapsing into the tear meniscus of patients with conjunctivochalasis. The method can monitor effectiveness of thermoreduction of conjunctivochalasis.

The role of inflammation and antiinflammation therapies in keratoconjunctivitis sicca

Purpose: To review and integrate recent advances in identifying the role of inflammation in the pathogenesis of dry eye conditions and the biological rationale and practical clinical aspects of newer, antiinflammatory theories. Methods: A comprehensive literature survey. Results and conclusion: Keratoconjunctivitis Sicca (KCS) is a multifactorial and complex disorder in which ocular surface inflammations play a central role. Identification of specific CD4-T-Cell pathways and the recent recognition of targeting of alpha-fodrin suggest a case for novel new therapeutic aspects such as anti-CD4 monoclonal antibodies, systemic linoleic and gamma-linolenic acids, and omega-6 essential fatty acids. Replacement of tear volume with nonpreserved wetting agents and standard typical antiinflammatory corticosteroid and/or cyclosporine A continues to be central current conventional therapy for KCS.

Noninvasive Assessment of Tear Stability with the Tear Stability Analysis System in Tear Dysfunction Patients

PURPOSE To evaluate tear film stability in patients with tear dysfunction and an asymptomatic control group by using the novel, noninvasive Tear Stability Analysis System (TSAS). METHODS In this prospective case-control study, 45 patients with dysfunctional tear syndrome (DTS) were stratified into three groups (1, 2, and 3/4) based on clinical severity, with higher scores indicating more severe symptoms; 25 asymptomatic control subjects were evaluated. TSAS measurements were performed with the RT-7000 Auto Refractor-Keratometer (Tomey Corporation, Nagoya, Japan). Images of ring mires projected onto the cornea every second for 6 seconds were captured and analyzed. Focal changes in brightness were calculated as numerical ring breakup (RBU) values, and the elapsed time when the cumulative values (RBU sum) exceeded a threshold was defined as the ring breakup time (RBUT). RESULTS RBUTs in the DTS groups were all significantly lower than those in the control subjects, with the lowest values found in DTS 3/4. RBUT was significantly shorter in DTS 3/4 than in DTS 1 (P<0.001). The change in RBU sum over a 6-second period in the DTS groups combined or between the individual groups was statistically significant (P<0.001), as was the difference between the 1- and 6-second values. For distinguishing between asymptomatic controls and DTS, the sensitivity and specificity of a 5.0-second RBUT cutoff were 82.0% and 60.0%, respectively. CONCLUSIONS The TSAS may be a useful, noninvasive instrument for evaluating tear stability and for classifying DTS severity.

Formulation and in vitro evaluation of cysteamine hydrochloride viscous solutions for the treatment of corneal cystinosis

In the present study, viscous solutions of cysteamine hydrochloride (CH) were prepared by using 0.5%, 1.0%, 1.5% or 3.0% of hydroxypropylmethylcellulose (HPMC) and were evaluated for their in-vitro characteristics and stability. Osmolalities, pH and viscosity of the formulations were determined. The influence of benzalkonium chloride and autoclave sterilization on solution characteristics was also investigated. For stability assessment, the viscous solutions were stored at +4 and +25 degrees C over 12 months. In-vitro characteristics and CH contents of the stored solutions were monitored. Irritation tests for the formulations were evaluated on rabbit eyes. Dialysis sac technique was used to perform in vitro release study of the solutions containing 1.0% and 1.5% HPMC. All of the viscous solutions tested showed non-newtonian (dilatant) flow behavior. Osmolality values were ranked between 351.2+/-6.2 and 355.1+/-7.9 mOsm kg(-1), and pH values were between 3.97+/-0.1 and 3.98+/-0.2 for all the solutions. Furthermore, no significant changes in dilatant behavior, osmolality or pH values of the pure HPMC solutions were observed. After addition of the excipients or CH-excipients, increased viscosity values were noted in these formulations. Neither benzalkonium chloride nor autoclave sterilization had any influence on viscosity, pH or osmolality values of the solution containing 1.5% HPMC. Stability studies showed that a faster decrease in the concentration of CH was observed in the formulations stored at 25 degrees C compared to those kept at 4 degrees C; no changes were determined in osmolality values of the solutions at all storage conditions. Increased pH and decreased viscosity values were noted in HPMC solutions containing CH and excipients, while no changes in these values were observed for pure HPMC solutions kept at 4 and 25 degrees C. In vitro release tests revealed that 81.2% and 85.3% of CH were released from the viscous solutions containing 1.5% and 1% HPMC, respectively, in 8h. No irritation was observed when the viscous solutions were tested on rabbit and human eyes.

Aqueous Tear Deficiency Increases Conjunctival Interferon-γ (IFN-γ) Expression and Goblet Cell Loss

PURPOSE To investigate the hypothesis that increased interferon-γ (IFN-γ) expression is associated with conjunctival goblet cell loss in subjects with tear dysfunction. METHODS Goblet cell density (GCD) was measured in impression cytology from the temporal bulbar conjunctiva, and gene expression was measured in cytology samples from the nasal bulbar conjunctiva obtained from 68 subjects, including normal control, meibomian gland disease (MGD), non-Sjögren syndrome (non-SSATD)-, and Sjögren syndrome (SSATD)-associated aqueous tear deficiency. Gene expression was evaluated by real-time PCR. Tear meniscus height (TMH) was measured by optical coherence tomography. Fluorescein and lissamine green dye staining evaluated corneal and conjunctival disease, respectively. Between-group mean differences and correlation coefficients were calculated. RESULTS Compared to control, IFN-γ expression was significantly higher in both ATD groups, and its receptor was higher in SSATD. Expression of IL-13 and its receptor was similar in all groups. Goblet cell density was lower in the SSATD group; expression of MUC5AC mucin was lower and cornified envelope precursor small proline-rich region (SPRR)-2G higher in both ATD groups. Interferon-γ transcript number was inversely correlated with GCD (r = -0.37, P < 0.04) and TMH (r = -0.37, P = 0.02), and directly correlated with lissamine green staining (r = 0.51, P < 0.001) and SPRR-2G expression (r = 0.32, P < 0.05). CONCLUSIONS Interferon-γ expression in the conjunctiva was higher in aqueous deficiency and correlated with goblet cell loss and severity of conjunctival disease. These results support findings of animal and culture studies showing that IFN-γ reduces conjunctival goblet cell number and mucin production.

Obstructive sleep apnoea prevalence in non-arteritic anterior ischaemic optic neuropathy

Aims The aim of this study was to show the prevalence of obstructive sleep apnoea (OSA) in non-arteritic anterior ischaemic optic neuropathy (NAION). Methods 20 patients diagnosed with NAION were included in the study. 20 age and sex matched subjects with similar risk factors for NAION, such as diabetes mellitus (DM) and hypertension (HT), constituted the control group. All cases underwent polysomnography for investigation of the presence of OSA. Cases with an Apnoea–Hypopnoea Index >5 were accepted as having OSA. Results Mean ages of the patients and controls were 60.90±8.14 and 61.15±7.23 years, respectively. There were no significant differences between the patient and control groups in terms of age, gender, body mass index, smoking/alcohol consumption or systemic diseases. In the patient group, 85% were diagnosed with OSA compared with 65% in the control group (p>0.05). Conclusions We found a high prevalence of OSA in patients with NAION but it was also high in the control group (p>0.05). This may be due to the fact that the two groups were matched for the same risk factors for NAION. The study indicates that OSA is not a risk factor for NAION in itself but is the contributing factor as it has effects on the vascular endothelium in DM, HT and atherosclerosis.

The Impact of the Boston Ocular Surface Prosthesis on Wavefront Higher-Order Aberrations

PURPOSE To evaluate the effect of the Boston Ocular Surface Prosthesis (Boston Foundation for Sight) on higher-order wavefront aberrations in eyes with keratoconus, eyes that have undergone penetrating keratoplasty, eyes that have undergone refractive surgery, and eyes with ocular surface diseases. DESIGN Prospective, clinical study. METHODS The study evaluated 56 eyes of 39 patients with irregular astigmatism who were treated with the Boston Ocular Surface Prosthesis when conventional treatments failed. Patients were sorted into 4 clinical groups based on the underlying cause of irregular astigmatism, including keratoconus (group 1), post-penetrating keratoplasty (group 2), post-refractive surgery (group 3), and ocular surface diseases (group 4). Another 6 eyes of 5 patients who were treated with rigid gas permeable lenses also were evaluated. Best-corrected visual acuity; topographic refractive indices, including spherical, cylindrical, spherical equivalent values; and higher-order and total wavefront aberration errors were noted at baseline and after fitting the lens. RESULTS In all groups, higher-order wavefront aberration error was noted to decrease significantly in eyes wearing the Boston Ocular Surface Prosthesis (P<.001, P=.001, P=.002, and P=.001, respectively). By post hoc analysis, significant differences in the level of higher-order aberrations were observed only between groups 1 and 4 (P=.012) and groups 1 and 2 (P=.033). In the overall group, mean correction rate of higher-order aberration error with the Boston Ocular Surface Prosthesis was 72.3%. However, in eyes with rigid gas permeable lenses, 2 eyes demonstrated increased higher-order aberration error, whereas the mean correction rate in other 4 eyes was only 42.5%. CONCLUSIONS With its unique structure, the Boston Ocular Surface Prosthesis was found to be very effective in reducing higher-order wavefront aberrations in patients with irregular astigmatism resulting from a number of corneal and ocular surface conditions who had not responded satisfactorily to conventional methods of optical correction.

Effect of pterygia on refractive indices, corneal topography, and ocular aberrations.

Purpose: To investigate the effect of different sizes of pterygium on ocular aberrations along with corneal refractive changes, keratometry, and corneal topography. Methods: Forty eyes of 34 patients who had different sizes of primary nasal pterygium and 40 eyes of 22 age- and sex-matched healthy subjects without a clinical diagnosis of pterygium or pinguecula were enrolled in this study. All patients underwent a measurement of uncorrected and best spectacle-corrected visual acuities, corneal topography, and ocular aberrations. The pterygia sizes were measured with a slit lamp by using a slit beam of light. Results: All indices (topographic/refractive spherical and astigmatic values and topographic/refractive spherical equivalent) were higher in the pterygia group than in the control group. Both horizontal length (Rho: 0.64 and P < 0.001) and width of pterygia (Rho: 0.68 and P < 0.01) were found to be correlated with corneal astigmatism. When the root mean square values of ocular aberrations were compared among the groups (control, small, medium, and large size pterygia), differences were found to be statistically significant regarding all parameters including total (P < 0.001), tilt (P < 0.001), higher order aberrations (P < 0.001), total coma (P < 0.001), total trefoil (P < 0.001), total tetrafoil (P < 0.001), total spherical aberrations (P = 0.004), and higher order astigmatism (P < 0.001). Moreover, the root mean square values of ocular aberrations seem to strongly correlate with both horizontal length and width of pterygia. Conclusions: Pterygia, particularly with larger sizes, seem to be correlated with increased ocular aberrations. Moreover, increase of ocular aberrations may become one of the indications for surgical treatment if this association is supported by further investigations.