Assessment of the ciliary muscle and scleral anterior thickness in high myopia by optical coherence tomography.

PURPOSE: To assess ciliary muscle (CM) and anterior scleral thickness (AST) dimensions in vivo in high myopia using swept-source optical coherence tomography (SS-OCT) and to compare with emmetropic and hyperopic subjects. METHODS: Cross-sectional study that included 34 high myopic patients (≥ -6 diopters [D]), 90 emmetropes (-1 to +1 D) and 38 hyperopic patients (≥ +3.5 D). CM thickness (CMT) and AST were measured in the temporal and nasal quadrants at 1, 2, and 3 mm from the scleral spur using SS-OCT. In addition, the length of the CM (CML) was evaluated. RESULTS: The dimensions of the CML and the CMT at any of their measurement points were greater in high myopes and emmetropes than in hyperopes, both in the nasal and temporal quadrants (P < .001). However, there were no differences between high myopes and emmetropes for any of the parameters (P ≥ .076) except for the CMT at 3 mm in the temporal quadrant (P < .001). There were no differences in the AST between high myopes, emmetropes and hyperopes, in any of the measurement points or quadrants studied (P > .05). CONCLUSIONS: The SS-OCT allows to measure the CM in vivo, not observing differences in its dimensions between high myopes and emmetropes, but they were smaller in hyperopes. In the measurement of the anterior sclera, no differences were observed between the three groups analyzed according to refraction.

Poster Session: Experimental assessment of scleral anisotropy using multi-meridian air-coupled ultrasonic optical coherence elastography.

Scleral biomechanics plays a key role in the understanding of myopia progression. In this study, we characterized the elastic properties of sclera using an air-coupled ultrasonic (ACUS) optical coherence elastography (OCE) system. New Zealand rabbit eyes (n=7) were measured (<24hr postmortem) in four scleral locations: superior/inferior temporal (ST, IT), and superior/inferior nasal (SN, IN) maintaining an intraocular pressure of 15 mmHg. Elastic waves were induced in the sclera, and wave propagation velocity and shear modulus were measured along two directions: circumferential (superior-inferior) and meridional (nasal-temporal). Wave velocity in scleral tissue ranged from 6 to 24 m/s and shear modulus from 11 to 150 kPa. Velocity was significantly higher (p<.001) in the circumferential vs. meridional directions in the following locations: ST:15.83±2.85 vs 9.43±1.68 m/s, IT:15.00±3.98 vs 8.93±1.53 m/s; SN:16.79±4.30 vs 9.27±1.47 m/s; and IN:13.92±3.85 vs 8.57±1.46 m/s. The average shear modulus in the circumferential was also significantly higher (p<.001) than in the meridional direction for all locations: 65.37±6.04 vs 22.55±1.36 kPa. These results show that the rabbit sclera is mechanically anisotropic with higher rigidity in the circumferential direction compared to the meridional direction. ACUS-OCE is a promising non-invasive method to quantify the biomechanical changes in scleral tissue for future studies involving myopia treatments.

Assessment of Scleral Contour Changes in High Myopia by Optical Coherence Tomography.

PURPOSE: This study aimed to establish and validate optical coherence tomography (OCT) based diagnostic criteria of high myopia. METHODS: This was a cross-sectional study including 100 eyes of high myopia with axial length larger than 26.5 mm and 100 control eyes, which were examined by spectral-domain OCT. Vertical and horizontal OCT of 9 mm scanning across fovea were analyzed. OCT characteristics including mirror artifact, scleral sink due to steep inclination of posterior sclera, scleral visibility, abnormality of outer retinal layer, foveoschisis, and dome-shaped macula were assessed in each group. RESULTS: The mean axial length was 28.65 ± 2.07 mm (range, 26.51-34.59 mm) in high myopia group and 23.79 ± 0.99 mm (range, 21.26-25.94 mm) in control group. Among the OCT characteristics noted at high frequency in the eyes with high myopia, three criteria achieving high sensitivity and specificity were determined: scleral sink over 500 µm, scleral visibility over 100 µm, and dome-shaped macula. Under conditions of presence of any of three criteria in either horizontal or vertical OCT scanning, the diagnostic sensitivity, specificity, positive predictive value, and negative predictive value for high myopia were found to be 95.0%, 98.0%, 98.0%, and 95.1%, respectively. In a new set of OCT images from 50 eyes with high myopia and 50 eyes of nonhigh myopia cases, the OCT-based criteria also proved similar level of diagnostic validity. CONCLUSIONS: The OCT-based criteria, which directly addressed posterior scleral contour changes, may lead to an intuitive and accurate diagnosis of high myopia. Also, the criteria may contribute to early detection and monitoring of eyes that cannot be defined as high myopia but can progress. OCT may be useful for monitoring high myopia patients as OCT can detect myopia-associated retinal pathologies as well as scleral contour changes.

Assessment of the anterior scleral thickness in central serous chorioretinopathy patients by optical coherence tomography.

PURPOSE: To assess the anterior scleral thickness (AST) and describe the presence of a visible supraciliary space (SCS) in central serous chorioretinopathy (CSC) patients by swept-source optical coherence tomography (SS-OCT). STUDY DESIGN: Cross-sectional comparative study. MATERIAL AND METHODS: Three groups were studied: 1) 64 eyes of 54 patients with CSC with persistent subretinal fluid (SRF); 2) 42 fellow eyes of CSC patients without SRF; 3) 65 eyes of 65 controls matched by age, sex and axial length (AL). The AST was measured in the temporal and nasal quadrants at 0, 1, and 2 mm from the scleral spur by SS-OCT. The presence of a visible SCS was also assessed. RESULTS: No differences were observed in the AST0 among the three groups (p≥ 0.665). The temporal AST1 was significantly thicker in the CSC group (530.3 ±67.1 µm) than in the controls (505.5 ±73.9; p=0.041). Mean AST2 was also thicker in the CSC group and the fellow eyes both for the temporal (519.4 ±89.1 µm and 519.8 ±98.5 µm respectively) and nasal quadrants (564.2 ±124.9 µm and 570.5 ±131.0 µm) than in the controls (450.1 ±76.8 and 473.3 ±111.6 µm) (all p≤0.001). A visible SCS was detected in the eyes of 8 CSC patients, in 4 fellow eyes and only in 1 control eye. CONCLUSIONS: AST measured by SS-OCT was significantly greater in CSC eyes than in healthy eyes. Also, a visible SCS was detected in CSC eyes. Thus, thicker sclera in CSC eyes could be associated with the physiopathology of this disease.

The relationship of ocular parameters with clinical parameters and disease-related quality of life in patients with systemic sclerosis: A cross-sectional study.

OBJECTIVE: To evaluate choroidal thickness (CT), corneal parameters, and scleral thickness (ST) in patients with systemic sclerosis (SSc) and to determine their relationship with disease-related quality of life (QoL). METHODS: The study included 38 patients with SSc and 40 healthy controls. A detailed ocular examination was performed on all participants. Corneal parameters such as K1, K2, Km, corneal volume (CV), central corneal thickness (CCT), and ST at a distance of 1000, 2000, and 3000 µm from the scleral spur were measured. CT was measured at five points, including the subfoveal area and the temporal and nasal points at radii of 750.0 and 1500.0 µm. The scleroderma health assessment questionnaire (SHAQ) was administered to SSc patients to investigate the disease-related QoL. RESULTS: Individuals with SSc had thicker ST at all distances from the scleral spur (P=0.008, P=0.001, P=0.002, respectively). All corneal parameters were significantly lower in the SSc group than in the control group (P < 0.05). Moreover, SSc patients had significantly lower median CT at N750.0, N1500.0, T750.0, and T1500.0 points and thinner subfoveal CT than healthy controls (P < 0.05). There was a weak-moderate negative correlation between ST and the components of the SHAQ scale and SHAQ-global. CONCLUSION: Despite not having ocular involvement, SSc patients had thicker ST but thinner CT and corneal parameters than healthy controls. This may indicate subclinical inflammation in patients with SSc. Only ST was affected by organ involvement and QoL among the ocular parameters.

The significance of ultrasound biomicroscopy in the objective assessment of post-trabeculectomy bleb success.

PURPOSE: To compare clinical characteristics and ultrasound biomicroscopy (UBM) measurements of cases with functional and non-functional blebs, and to identify potential risk factors capable of affecting UBM parameters. METHODS: Thirty-one patients aged 40-79 were included. Following trabeculectomy, cases were divided into two groups as those with functional bleb (Group 1, n = 20) and those with non-functional bleb (Group 2, n = 11). UBM was performed. RESULTS: In Group 1 compared to Group 2, lower postoperative intraocular pressure (IOP) (12.1 ± 1.7 vs 27.2 ± 3.2 mmHg, p < 0.001), greater bleb height (1.0 ± 0.2 vs 0.5 ± 0.3 mm, p < 0.001), greater scleral route visibility [16/20 (80%) vs 4/11 (36.4%), p = 0.023] and lower bleb reflectivity (1.8 ± 0.2 vs 2.4 ± 0.4, p = 0.015) were observed. In Group 1, as postoperative IOP decreased, bleb height and scleral route visibility increased (r = -0.387, p = 0.029 for bleb height; r = -0.374, p = 0.033 for scleral route), and bleb reflectivity decreased (r = 0.359, p = 0.042). In Group 1, as duration of preoperative antiglaucoma drug use increased, bleb reflectivity increased (r = 0.348, p = 0.046). Preoperative IOP and number of preoperative antiglaucoma drug use had no effect on UBM parameters in groups (p > 0.05). CONCLUSION: UBM is useful in assessing bleb success. Lower bleb reflectivity, greater bleb height and greater scleral route visibility indicate that the bleb is functional. To the best of our knowledge, this is the first study investigating effects of preoperative IOP, number and duration of preoperative antiglaucoma drug use on UBM parameters. In cases with functional bleb, duration of preoperative drug use affects only bleb reflectivity, while postoperative IOP affects bleb height, scleral route visibility and bleb reflectivity.

Clinical Assessment of Scleral Canal Area in Glaucoma Using Spectral-Domain Optical Coherence Tomography.

PURPOSE: To investigate anterior scleral canal (ASC) area in the eyes with glaucoma using spectral-domain optical coherence tomography (SDOCT). DESIGN: Cross-sectional study. METHODS: This study included 206 eyes of 103 patients with glaucoma, classified as 66 eyes of 33 patients with unilateral glaucoma and 140 eyes of 70 patients with bilateral glaucoma. Radial scan enhanced depth imaging SDOCT centered on the optic disc was performed, and parameters that present ASC area such as ASC opening and the largest ASC area were obtained in each eye. The largest ASC area was the largest cross-sectional area of the ASC region identified between the ASC opening and anterior lamina cribrosa insertion. These parameters were compared between eyes with and without glaucoma in unilateral glaucoma, and eyes with worse and better visual field defect (VFD) in bilateral glaucoma. RESULTS: In the patients with unilateral glaucoma, ASC opening and largest ASC area were significantly larger in the eyes with glaucoma than in those without glaucoma (both P < .001). In bilateral glaucoma, these parameters were significantly larger in the eyes with worse VFD than in those with better VFD (P = .0080 and P = .0018, respectively). Intereye differences of the ASC parameters in the glaucoma patients were significantly greater than that in the normal subjects. CONCLUSIONS: Significantly larger ASC area was first observed in the living human eyes with glaucoma compared to the normal eyes. Further longitudinal studies are required to determine if the ASC area is useful in the prevention and treatment of glaucoma.

Anterior chamber angle assessment using gonioscopy and ultrasound biomicroscopy.

PURPOSE: Comparison of anterior chamber angle measurements using ultrasound biomicroscopy (UBM) and gonioscopy. METHODS: Five hundred subjects were evaluated for grading of angle width by the Shaffer method. UBM was done in the same group to document angle width, angle opening distance (AOD 500), and anterior chamber depth. Biometric parameters were documented in all subjects. UBM and gonioscopic findings were compared. RESULTS: A study was conducted in 282 men and 218 women with a mean age of 57.32 +/- 12.48 years. Gonioscopic grading was used to segregate occludable (slit-like, grades 1 and 2) from nonoccludable (grades 3 and 4) angles. Subjective assessment by gonioscopy resulted in an overestimation of angle width within the occludable group when compared with values obtained by UBM. This did not affect the segregation of occludable versus nonoccludable angles by gonioscopy. Biometric parameters in eyes with occludable angles were significantly lower in comparison with eyes with nonoccludable angles, except for lens thickness. AOD 500 correlated well with angle width. CONCLUSIONS: We concluded that clinical segregation into occludable and nonoccludable angles by an experienced observer using gonioscopy is fairly accurate. However, UBM is required for objective quantification of angles, and AOD 500 can be a reliable and standard parameter to grade angle width.

Ultrasound biomicroscopy in the assessment of anterior scleral disease.

High-frequency ultrasound biomicroscopy is a new method of examining subsurface anterior segment structures of the eye at microscopic resolution. The sclera has a high internal reflectivity and can be differentiated from the cornea, and overlying and underlying tissue. Using this modality, we examined 18 patients with various manifestations of scleral disease. Localized anterior staphyloma could be differentiated from other causes of a black spot on the scleral surface. Episcleral thickening could be differentiated from involvement of the sclera itself. Different patterns of scleral involvement could be imaged including diffuse low-reflective mottling, low-reflective nodules extending into the scleral substance, and scleral thinning. Scleral thinning could be assessed and quantified. Underlying changes in the vitreous could be detected. Ultrasound biomicroscopy was a useful adjunct to clinical examination in the assessment of anterior scleral disease.